List of the most common methods used in risk analysis.
\\n\\n
More than half of the publishers listed alongside IntechOpen (18 out of 30) are Social Science and Humanities publishers. IntechOpen is an exception to this as a leader in not only Open Access content but Open Access content across all scientific disciplines, including Physical Sciences, Engineering and Technology, Health Sciences, Life Science, and Social Sciences and Humanities.
\\n\\nOur breakdown of titles published demonstrates this with 47% PET, 31% HS, 18% LS, and 4% SSH books published.
\\n\\n“Even though ItechOpen has shown the potential of sci-tech books using an OA approach,” other publishers “have shown little interest in OA books.”
\\n\\nAdditionally, each book published by IntechOpen contains original content and research findings.
\\n\\nWe are honored to be among such prestigious publishers and we hope to continue to spearhead that growth in our quest to promote Open Access as a true pioneer in OA book publishing.
\\n\\n\\n\\n
\\n"}]',published:!0,mainMedia:{caption:"IntechOpen Maintains",originalUrl:"/media/original/113"}},components:[{type:"htmlEditorComponent",content:'
Simba Information has released its Open Access Book Publishing 2020 - 2024 report and has again identified IntechOpen as the world’s largest Open Access book publisher by title count.
\n\nSimba Information is a leading provider for market intelligence and forecasts in the media and publishing industry. The report, published every year, provides an overview and financial outlook for the global professional e-book publishing market.
\n\nIntechOpen, De Gruyter, and Frontiers are the largest OA book publishers by title count, with IntechOpen coming in at first place with 5,101 OA books published, a good 1,782 titles ahead of the nearest competitor.
\n\nSince the first Open Access Book Publishing report published in 2016, IntechOpen has held the top stop each year.
\n\n\n\nMore than half of the publishers listed alongside IntechOpen (18 out of 30) are Social Science and Humanities publishers. IntechOpen is an exception to this as a leader in not only Open Access content but Open Access content across all scientific disciplines, including Physical Sciences, Engineering and Technology, Health Sciences, Life Science, and Social Sciences and Humanities.
\n\nOur breakdown of titles published demonstrates this with 47% PET, 31% HS, 18% LS, and 4% SSH books published.
\n\n“Even though ItechOpen has shown the potential of sci-tech books using an OA approach,” other publishers “have shown little interest in OA books.”
\n\nAdditionally, each book published by IntechOpen contains original content and research findings.
\n\nWe are honored to be among such prestigious publishers and we hope to continue to spearhead that growth in our quest to promote Open Access as a true pioneer in OA book publishing.
\n\n\n\n
\n'}],latestNews:[{slug:"webinar-introduction-to-open-science-wednesday-18-may-1-pm-cest-20220518",title:"Webinar: Introduction to Open Science | Wednesday 18 May, 1 PM CEST"},{slug:"step-in-the-right-direction-intechopen-launches-a-portfolio-of-open-science-journals-20220414",title:"Step in the Right Direction: IntechOpen Launches a Portfolio of Open Science Journals"},{slug:"let-s-meet-at-london-book-fair-5-7-april-2022-olympia-london-20220321",title:"Let’s meet at London Book Fair, 5-7 April 2022, Olympia London"},{slug:"50-books-published-as-part-of-intechopen-and-knowledge-unlatched-ku-collaboration-20220316",title:"50 Books published as part of IntechOpen and Knowledge Unlatched (KU) Collaboration"},{slug:"intechopen-joins-the-united-nations-sustainable-development-goals-publishers-compact-20221702",title:"IntechOpen joins the United Nations Sustainable Development Goals Publishers Compact"},{slug:"intechopen-signs-exclusive-representation-agreement-with-lsr-libros-servicios-y-representaciones-s-a-de-c-v-20211123",title:"IntechOpen Signs Exclusive Representation Agreement with LSR Libros Servicios y Representaciones S.A. de C.V"},{slug:"intechopen-expands-partnership-with-research4life-20211110",title:"IntechOpen Expands Partnership with Research4Life"},{slug:"introducing-intechopen-book-series-a-new-publishing-format-for-oa-books-20210915",title:"Introducing IntechOpen Book Series - A New Publishing Format for OA Books"}]},book:{item:{type:"book",id:"2828",leadTitle:null,fullTitle:"Fiber Reinforced Polymers - The Technology Applied for Concrete Repair",title:"Fiber Reinforced Polymers",subtitle:"The Technology Applied for Concrete Repair",reviewType:"peer-reviewed",abstract:"Fiber Reinforced Polymers are by no means new to this world. It is only because of our fascination with petrochemical and non-petrochemical products that these wonderful materials exist. In fact, the polymers can be considered and used in the construction and construction repair. The petrochemical polymers are of low cost and are used more that natural materials. The Fiber Reinforced Polymers research is currently increasing and entails a quickly expanding field due to the vast range of both traditional and special applications in accordance to their characteristics and properties. Fiber Reinforced Polymers are related to the improvement of environmental parameters, consist of important areas of research demonstrating high potential and particularly great interest, as civil construction and concrete repair.",isbn:null,printIsbn:"978-953-51-0938-9",pdfIsbn:"978-953-51-6292-6",doi:"10.5772/3162",price:119,priceEur:129,priceUsd:155,slug:"fiber-reinforced-polymers-the-technology-applied-for-concrete-repair",numberOfPages:242,isOpenForSubmission:!1,isInWos:null,isInBkci:!1,hash:"4922c593466cc822b281fe7cc7d7fef6",bookSignature:"Martin Alberto Masuelli",publishedDate:"January 23rd 2013",coverURL:"https://cdn.intechopen.com/books/images_new/2828.jpg",numberOfDownloads:64764,numberOfWosCitations:113,numberOfCrossrefCitations:65,numberOfCrossrefCitationsByBook:40,numberOfDimensionsCitations:133,numberOfDimensionsCitationsByBook:45,hasAltmetrics:1,numberOfTotalCitations:311,isAvailableForWebshopOrdering:!0,dateEndFirstStepPublish:"February 21st 2012",dateEndSecondStepPublish:"March 13th 2012",dateEndThirdStepPublish:"June 9th 2012",dateEndFourthStepPublish:"July 9th 2012",dateEndFifthStepPublish:"January 23rd 2013",currentStepOfPublishingProcess:5,indexedIn:"1,2,3,4,5,6,7",editedByType:"Edited by",kuFlag:!1,featuredMarkup:null,editors:[{id:"99994",title:"Dr.",name:"Martin",middleName:"Alberto",surname:"Masuelli",slug:"martin-masuelli",fullName:"Martin Masuelli",profilePictureURL:"https://mts.intechopen.com/storage/users/99994/images/system/99994.png",biography:"Martin A. Masuelli is a Inv. Adj. professor at the Instituto de Física Aplicada, National Scientific and Technical Research Council (CONICET), and an associate professor at the National University of San Luis (UNSL), Argentina. He holds a master’s degree and a Ph.D. in Membrane Technology from UNSL. He has served as the director of the Physics Chemistry Service Laboratory, UNSL, since 2014. He is an expert in polysaccharides and the physical chemistry of macromolecules. Dr. Masuelli has authored or co-authored more than thirty-two peer-reviewed international publications, eight book chapters, and seventy communications in international congresses. He has also edited seven books. He is a member of the Sociedad Argentina de Ciencia y Tecnología Ambiental, Asociación Argentina de Fisicoquímica y Química Inorgánica, and Asociación Argentina de Tecnólogos de Alimentos. He is editor in chief and founder of the Journal of Polymer and Biopolymers Physics Chemistry and an editorial board member for various other journals. His research interests include hydropolymers, biopolymers (separative, purification processes, and characterization), physiochemistry of macromolecules, membrane technology and design (NF-UF-MF), and separative processes.",institutionString:"National University of San Luis",position:null,outsideEditionCount:0,totalCites:0,totalAuthoredChapters:"3",totalChapterViews:"0",totalEditedBooks:"3",institution:{name:"National University of San Luis",institutionURL:null,country:{name:"Argentina"}}}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,coeditorOne:null,coeditorTwo:null,coeditorThree:null,coeditorFour:null,coeditorFive:null,topics:[{id:"915",title:"Polymers",slug:"materials-science-biochemistry-polymers"}],chapters:[{id:"41941",title:"Introduction of Fibre-Reinforced Polymers − Polymers and Composites: Concepts, Properties and Processes",doi:"10.5772/54629",slug:"introduction-of-fibre-reinforced-polymers-polymers-and-composites-concepts-properties-and-processes",totalDownloads:27967,totalCrossrefCites:35,totalDimensionsCites:79,hasAltmetrics:1,abstract:null,signatures:"Martin Alberto Masuelli",downloadPdfUrl:"/chapter/pdf-download/41941",previewPdfUrl:"/chapter/pdf-preview/41941",authors:[{id:"99994",title:"Dr.",name:"Martin",surname:"Masuelli",slug:"martin-masuelli",fullName:"Martin Masuelli"}],corrections:null},{id:"42195",title:"Natural Fibre Bio-Composites Incorporating Poly(Lactic Acid)",doi:"10.5772/52253",slug:"natural-fibre-bio-composites-incorporating-poly-lactic-acid-",totalDownloads:6562,totalCrossrefCites:16,totalDimensionsCites:28,hasAltmetrics:0,abstract:null,signatures:"Eustathios Petinakis, Long Yu, George Simon and Katherine Dean",downloadPdfUrl:"/chapter/pdf-download/42195",previewPdfUrl:"/chapter/pdf-preview/42195",authors:[{id:"18113",title:"Prof.",name:"Long",surname:"Yu",slug:"long-yu",fullName:"Long Yu"},{id:"153507",title:"Ph.D. Student",name:"Eustathios",surname:"Petinakis",slug:"eustathios-petinakis",fullName:"Eustathios Petinakis"}],corrections:null},{id:"38042",title:"The Use of Fiber Reinforced Plastic for The Repair and Strengthening of Existing Reinforced Concrete Structural Elements Damaged by Earthquakes",doi:"10.5772/51326",slug:"the-use-of-fiber-reinforced-plastic-for-the-repair-and-strengthening-of-existing-reinforced-concrete",totalDownloads:3102,totalCrossrefCites:0,totalDimensionsCites:5,hasAltmetrics:1,abstract:null,signatures:"George C. Manos and Kostas V. Katakalos",downloadPdfUrl:"/chapter/pdf-download/38042",previewPdfUrl:"/chapter/pdf-preview/38042",authors:[{id:"152143",title:"Prof.",name:"George",surname:"Manos",slug:"george-manos",fullName:"George Manos"}],corrections:null},{id:"38948",title:"Applying Post-Tensioning Technique to Improve the Performance of FRP Post-Strengthening",doi:"10.5772/51523",slug:"applying-post-tensioning-technique-to-improve-the-performance-of-frp-post-strengthening",totalDownloads:3015,totalCrossrefCites:0,totalDimensionsCites:2,hasAltmetrics:1,abstract:null,signatures:"Mônica Regina Garcez, Leila Cristina Meneghetti and Luiz Carlos Pinto da Silva Filho",downloadPdfUrl:"/chapter/pdf-download/38948",previewPdfUrl:"/chapter/pdf-preview/38948",authors:[{id:"151901",title:"Dr.",name:"Mônica",surname:"Garcez",slug:"monica-garcez",fullName:"Mônica Garcez"},{id:"153100",title:"Dr.",name:"Leila",surname:"Menegthetti",slug:"leila-menegthetti",fullName:"Leila Menegthetti"},{id:"153101",title:"Dr.",name:"Luiz Carlos Pinto",surname:"Silva Filho",slug:"luiz-carlos-pinto-silva-filho",fullName:"Luiz Carlos Pinto Silva Filho"}],corrections:null},{id:"38557",title:"Hybrid FRP Sheet – PP Fiber Rope Strengthening of Concrete Members",doi:"10.5772/51425",slug:"hybrid-frp-sheet-pp-fiber-rope-strengthening-of-concrete-members",totalDownloads:2667,totalCrossrefCites:0,totalDimensionsCites:1,hasAltmetrics:0,abstract:null,signatures:"Theodoros C. Rousakis",downloadPdfUrl:"/chapter/pdf-download/38557",previewPdfUrl:"/chapter/pdf-preview/38557",authors:[{id:"151952",title:"Dr.",name:"Theodoros",surname:"Rousakis",slug:"theodoros-rousakis",fullName:"Theodoros Rousakis"}],corrections:null},{id:"38513",title:"Circular and Square Concrete Columns Externally Confined by CFRP Composite: Experimental Investigation and Effective Strength Models",doi:"10.5772/51589",slug:"circular-and-square-concrete-columns-externally-confined-by-cfrp-composite-experimental-investigatio",totalDownloads:19080,totalCrossrefCites:14,totalDimensionsCites:18,hasAltmetrics:1,abstract:null,signatures:"Riad Benzaid and Habib-Abdelhak Mesbah",downloadPdfUrl:"/chapter/pdf-download/38513",previewPdfUrl:"/chapter/pdf-preview/38513",authors:[{id:"152343",title:"Dr.",name:"Riad",surname:"Benzaid",slug:"riad-benzaid",fullName:"Riad Benzaid"},{id:"163953",title:"Dr.",name:"Habib-Abdelhak",surname:"Mesbah",slug:"habib-abdelhak-mesbah",fullName:"Habib-Abdelhak Mesbah"}],corrections:null},{id:"39870",title:"Analysis of Nonlinear Composite Members Including Bond-Slip",doi:"10.5772/51446",slug:"analysis-of-nonlinear-composite-members-including-bond-slip",totalDownloads:2377,totalCrossrefCites:0,totalDimensionsCites:0,hasAltmetrics:0,abstract:null,signatures:"Manal K. Zaki",downloadPdfUrl:"/chapter/pdf-download/39870",previewPdfUrl:"/chapter/pdf-preview/39870",authors:[{id:"152813",title:"Dr.",name:"Manal",surname:"Zaki",slug:"manal-zaki",fullName:"Manal Zaki"}],corrections:null}],productType:{id:"1",title:"Edited Volume",chapterContentType:"chapter",authoredCaption:"Edited by"},subseries:null,tags:null},relatedBooks:[{type:"book",id:"8504",title:"Pectins",subtitle:"Extraction, Purification, Characterization and Applications",isOpenForSubmission:!1,hash:"ff1acef627b277c575a10b3259dd331b",slug:"pectins-extraction-purification-characterization-and-applications",bookSignature:"Martin Masuelli",coverURL:"https://cdn.intechopen.com/books/images_new/8504.jpg",editedByType:"Edited by",editors:[{id:"99994",title:"Dr.",name:"Martin",surname:"Masuelli",slug:"martin-masuelli",fullName:"Martin Masuelli"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"3043",title:"New Polymers for Special Applications",subtitle:null,isOpenForSubmission:!1,hash:"dd782fff3bea8992c224dfd3280d6cd1",slug:"new-polymers-for-special-applications",bookSignature:"Ailton De Souza Gomes",coverURL:"https://cdn.intechopen.com/books/images_new/3043.jpg",editedByType:"Edited by",editors:[{id:"135416",title:"Dr.",name:"Ailton",surname:"De Souza Gomes",slug:"ailton-de-souza-gomes",fullName:"Ailton De Souza Gomes"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"1573",title:"Thermoplastic Elastomers",subtitle:null,isOpenForSubmission:!1,hash:"68733430093bd948f36fd95ab2ff4746",slug:"thermoplastic-elastomers",bookSignature:"Adel Zaki El-Sonbati",coverURL:"https://cdn.intechopen.com/books/images_new/1573.jpg",editedByType:"Edited by",editors:[{id:"98324",title:"Prof.",name:"Adel",surname:"El-Sonbati",slug:"adel-el-sonbati",fullName:"Adel El-Sonbati"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"467",title:"Carbon Nanotubes",subtitle:"Polymer Nanocomposites",isOpenForSubmission:!1,hash:null,slug:"carbon-nanotubes-polymer-nanocomposites",bookSignature:"Siva Yellampalli",coverURL:"https://cdn.intechopen.com/books/images_new/467.jpg",editedByType:"Edited by",editors:[{id:"62863",title:"Dr.",name:"Siva",surname:"Yellampalli",slug:"siva-yellampalli",fullName:"Siva Yellampalli"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"2003",title:"Polyurethane",subtitle:null,isOpenForSubmission:!1,hash:"7391b5a0085d7c0aa0a5c75ee6f275b2",slug:"polyurethane",bookSignature:"Fahmina Zafar and Eram Sharmin",coverURL:"https://cdn.intechopen.com/books/images_new/2003.jpg",editedByType:"Edited by",editors:[{id:"89672",title:"Dr.",name:"Fahmina",surname:"Zafar",slug:"fahmina-zafar",fullName:"Fahmina Zafar"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"2383",title:"Polyester",subtitle:null,isOpenForSubmission:!1,hash:"79fd9d6314f8e1abd60d7e21896ce878",slug:"polyester",bookSignature:"Hosam El-Din M. Saleh",coverURL:"https://cdn.intechopen.com/books/images_new/2383.jpg",editedByType:"Edited by",editors:[{id:"144691",title:"Prof.",name:"Hosam M.",surname:"Saleh",slug:"hosam-m.-saleh",fullName:"Hosam M. Saleh"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"2385",title:"Polymerization",subtitle:null,isOpenForSubmission:!1,hash:"e83b64f8e9875e507d879fede9f34d1a",slug:"polymerization",bookSignature:"Ailton De Souza Gomes",coverURL:"https://cdn.intechopen.com/books/images_new/2385.jpg",editedByType:"Edited by",editors:[{id:"135416",title:"Dr.",name:"Ailton",surname:"De Souza Gomes",slug:"ailton-de-souza-gomes",fullName:"Ailton De Souza Gomes"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"2805",title:"High Performance Polymers - Polyimides Based",subtitle:"From Chemistry to Applications",isOpenForSubmission:!1,hash:"45412ef8f76c275a84f6052ab6076355",slug:"high-performance-polymers-polyimides-based-from-chemistry-to-applications",bookSignature:"Marc J.M. Abadie",coverURL:"https://cdn.intechopen.com/books/images_new/2805.jpg",editedByType:"Edited by",editors:[{id:"145543",title:"Prof.",name:"Marc",surname:"Abadie",slug:"marc-abadie",fullName:"Marc Abadie"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"2434",title:"Advanced Elastomers",subtitle:"Technology, Properties and Applications",isOpenForSubmission:!1,hash:"5af149f1724b92c429f9619a8ee87816",slug:"advanced-elastomers-technology-properties-and-applications",bookSignature:"Anna Boczkowska",coverURL:"https://cdn.intechopen.com/books/images_new/2434.jpg",editedByType:"Edited by",editors:[{id:"137336",title:"D.Sc.",name:"Anna",surname:"Boczkowska",slug:"anna-boczkowska",fullName:"Anna Boczkowska"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"1797",title:"Polypropylene",subtitle:null,isOpenForSubmission:!1,hash:"45b694d8c36144473ad19233fe4a4359",slug:"polypropylene",bookSignature:"Fatih Dogan",coverURL:"https://cdn.intechopen.com/books/images_new/1797.jpg",editedByType:"Edited by",editors:[{id:"105969",title:"Dr.",name:"Fatih",surname:"Dogan",slug:"fatih-dogan",fullName:"Fatih Dogan"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}}],ofsBooks:[]},correction:{item:{id:"66066",slug:"erratum-microbial-responses-to-different-operating-practices-for-biogas-production-systems",title:"Erratum - Microbial Responses to Different Operating Practices for Biogas Production Systems",doi:null,correctionPDFUrl:"https://cdn.intechopen.com/pdfs/66066.pdf",downloadPdfUrl:"/chapter/pdf-download/66066",previewPdfUrl:"/chapter/pdf-preview/66066",totalDownloads:null,totalCrossrefCites:null,bibtexUrl:"/chapter/bibtex/66066",risUrl:"/chapter/ris/66066",chapter:{id:"65614",slug:"microbial-responses-to-different-operating-practices-for-biogas-production-systems",signatures:"Maria Westerholm and Anna Schnürer",dateSubmitted:"June 11th 2018",dateReviewed:"November 30th 2018",datePrePublished:"February 12th 2019",datePublished:"September 4th 2019",book:{id:"6839",title:"Anaerobic Digestion",subtitle:null,fullTitle:"Anaerobic Digestion",slug:"anaerobic-digestion",publishedDate:"September 4th 2019",bookSignature:"J. Rajesh Banu",coverURL:"https://cdn.intechopen.com/books/images_new/6839.jpg",licenceType:"CC BY 3.0",editedByType:"Edited by",editors:[{id:"218539",title:"Dr.",name:"Rajesh Banu",middleName:null,surname:"Jeyakumar",slug:"rajesh-banu-jeyakumar",fullName:"Rajesh Banu Jeyakumar"}],productType:{id:"1",title:"Edited Volume",chapterContentType:"chapter",authoredCaption:"Edited by"}},authors:[{id:"262546",title:"Prof.",name:"Anna",middleName:null,surname:"Schnürer",fullName:"Anna Schnürer",slug:"anna-schnurer",email:"anna.schnurer@slu.se",position:null,institution:null},{id:"263116",title:"Dr.",name:"Maria",middleName:null,surname:"Westerholm",fullName:"Maria Westerholm",slug:"maria-westerholm",email:"Maria.Westerholm@slu.se",position:null,institution:null}]}},chapter:{id:"65614",slug:"microbial-responses-to-different-operating-practices-for-biogas-production-systems",signatures:"Maria Westerholm and Anna Schnürer",dateSubmitted:"June 11th 2018",dateReviewed:"November 30th 2018",datePrePublished:"February 12th 2019",datePublished:"September 4th 2019",book:{id:"6839",title:"Anaerobic Digestion",subtitle:null,fullTitle:"Anaerobic Digestion",slug:"anaerobic-digestion",publishedDate:"September 4th 2019",bookSignature:"J. Rajesh Banu",coverURL:"https://cdn.intechopen.com/books/images_new/6839.jpg",licenceType:"CC BY 3.0",editedByType:"Edited by",editors:[{id:"218539",title:"Dr.",name:"Rajesh Banu",middleName:null,surname:"Jeyakumar",slug:"rajesh-banu-jeyakumar",fullName:"Rajesh Banu Jeyakumar"}],productType:{id:"1",title:"Edited Volume",chapterContentType:"chapter",authoredCaption:"Edited by"}},authors:[{id:"262546",title:"Prof.",name:"Anna",middleName:null,surname:"Schnürer",fullName:"Anna Schnürer",slug:"anna-schnurer",email:"anna.schnurer@slu.se",position:null,institution:null},{id:"263116",title:"Dr.",name:"Maria",middleName:null,surname:"Westerholm",fullName:"Maria Westerholm",slug:"maria-westerholm",email:"Maria.Westerholm@slu.se",position:null,institution:null}]},book:{id:"6839",title:"Anaerobic Digestion",subtitle:null,fullTitle:"Anaerobic Digestion",slug:"anaerobic-digestion",publishedDate:"September 4th 2019",bookSignature:"J. Rajesh Banu",coverURL:"https://cdn.intechopen.com/books/images_new/6839.jpg",licenceType:"CC BY 3.0",editedByType:"Edited by",editors:[{id:"218539",title:"Dr.",name:"Rajesh Banu",middleName:null,surname:"Jeyakumar",slug:"rajesh-banu-jeyakumar",fullName:"Rajesh Banu Jeyakumar"}],productType:{id:"1",title:"Edited Volume",chapterContentType:"chapter",authoredCaption:"Edited by"}}},ofsBook:{item:{type:"book",id:"8742",leadTitle:null,title:"Clinical Urine Tests",subtitle:null,reviewType:"peer-reviewed",abstract:"
\r\n\tThe book project Clinical Urine Tests will present the kidneys as a very important organ for the health of each individual. It will describe their function, the physiology of the emergence of urine and the most common disorders. The book will also focus on matrix urine and on tests that are routinely performed in the laboratory. These tests are roughly divided into qualitative and quantitative, and microscopic examination of the sediment. It will also cover the presentation of reference values. Especially supplement with reference values separately for adults, children and pregnant women.
\r\n\r\n\tMost common urinary tract infections, the antibiotic treatment protocols, and the onset of resistance and the evidence-based treatment will also be discussed. Some chapters may refer to chronic kidney disease, monitoring through laboratory indicators and renal failure leading to dialysis.
\r\n\r\n\tThe contents of the book will be written by multiple authors and edited by experts in the field. Authors are not limited in terms of topic, but encouraged to present a chapter proposal that best suits their current research efforts. Later, when all chapter proposals are collected, the editor will provide a more specific direction of the book.
",isbn:null,printIsbn:"979-953-307-X-X",pdfIsbn:null,doi:null,price:0,priceEur:0,priceUsd:0,slug:null,numberOfPages:0,isOpenForSubmission:!1,isSalesforceBook:!1,isNomenclature:!1,hash:"bab4efe60bb1b6ba61f04bbc7aca45e2",bookSignature:"Prof. Joško Osredkar",publishedDate:null,coverURL:"https://cdn.intechopen.com/books/images_new/8742.jpg",keywords:"Kidney function, urine production, Urine analysis, qualitative tests, microscopic examination, quantitative tests, urinary tract infection, collection of urine, processing of urine, culture results interpretation, tumor markers in urine, molecular genetic tests",numberOfDownloads:null,numberOfWosCitations:0,numberOfCrossrefCitations:0,numberOfDimensionsCitations:0,numberOfTotalCitations:0,isAvailableForWebshopOrdering:!0,dateEndFirstStepPublish:"May 2nd 2019",dateEndSecondStepPublish:"May 23rd 2019",dateEndThirdStepPublish:"July 22nd 2019",dateEndFourthStepPublish:"October 10th 2019",dateEndFifthStepPublish:"December 9th 2019",dateConfirmationOfParticipation:null,remainingDaysToSecondStep:"3 years",secondStepPassed:!0,areRegistrationsClosed:!0,currentStepOfPublishingProcess:5,editedByType:null,kuFlag:!1,biosketch:null,coeditorOneBiosketch:null,coeditorTwoBiosketch:null,coeditorThreeBiosketch:null,coeditorFourBiosketch:null,coeditorFiveBiosketch:null,editors:[{id:"66896",title:"Prof.",name:"Joško",middleName:null,surname:"Osredkar",slug:"josko-osredkar",fullName:"Joško Osredkar",profilePictureURL:"https://mts.intechopen.com/storage/users/66896/images/system/66896.jpeg",biography:"Prof.dr. Joško Osredkar is a full professor in the field of clinical biochemistry (Research number – 10691). He was born on January 27, 1955. in Jesenice. \r\nAfter completing elementary school, he enrolled at the gymnasium in Jesenice. In 1973. he enrolled at the Department of Pharmacy at the Faculty of Natural Sciences and Technology (FNT) and graduated in July 1981. He started working at the University Medical Centre Ljubljana in 1979. In 1987 he became a specialist in medical biochemistry, and in 1988 obtained a master's degree and a doctorate in 1992.\r\nIn 1990, he joined the FNT - Department of Pharmacy as an assistant, and since 2005 has been a full professor of clinical biochemistry.\r\nAs the head of the research group (KIKKB), he is involved in the projects with National Research Agency. He participates in several other projects, but also in the research program - Metabolic and congenital factors of reproductive health, labor I, II going to III. Within the framework of FP6, lead Slovenian Research Group in the project Influence of long-term exposure to low concentrations of elements in food in a sensitive population - Public health impact of long-term, low-level mixed element exposure and susceptible population strata (PHIME).\r\nHis main research field today is oxidative stress during pregnancy and the study of oxidative stress in the unborn child, the child immediately after birth to the school period, seeking the association of oxidative stress during pregnancy with preeclampsia, with Down syndrome and autism.\r\nIn 2000, the Minister of Health awarded him with the title of councilor and in 2007 the senior counselor.\r\nIn 1993, he was appointed as a representative of Slovenia to the Monitoring Group for controlling the implementation of the European Convention against Doping in Sport in the World of Europe. At the time of the establishment of the Slovenian National Anti-Doping Commission (NAK) in 1996, he became its first president. This function is carried out to a certain extent (transitional period - until the establishment of the institution). In 2003, the World Anti-Doping Agency (WADA) appointed him as a member of the Doping Control Expert Group.\r\nIn 2009, the International Olympic Committee (IOC) award him special recognition in the field of the fight against doping.",institutionString:"University of Ljubljana",position:null,outsideEditionCount:0,totalCites:0,totalAuthoredChapters:"1",totalChapterViews:"0",totalEditedBooks:"0",institution:{name:"University of Ljubljana",institutionURL:null,country:{name:"Slovenia"}}}],coeditorOne:null,coeditorTwo:null,coeditorThree:null,coeditorFour:null,coeditorFive:null,topics:[{id:"16",title:"Medicine",slug:"medicine"}],chapters:null,productType:{id:"1",title:"Edited Volume",chapterContentType:"chapter",authoredCaption:"Edited by"},personalPublishingAssistant:{id:"300344",firstName:"Danijela",lastName:"Pintur",middleName:null,title:"Ms.",imageUrl:"https://mts.intechopen.com/storage/users/300344/images/8496_n.png",email:"danijela.p@intechopen.com",biography:null}},relatedBooks:[{type:"book",id:"6550",title:"Cohort Studies in Health Sciences",subtitle:null,isOpenForSubmission:!1,hash:"01df5aba4fff1a84b37a2fdafa809660",slug:"cohort-studies-in-health-sciences",bookSignature:"R. Mauricio Barría",coverURL:"https://cdn.intechopen.com/books/images_new/6550.jpg",editedByType:"Edited by",editors:[{id:"88861",title:"Dr.",name:"R. Mauricio",surname:"Barría",slug:"r.-mauricio-barria",fullName:"R. Mauricio Barría"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"9500",title:"Recent Advances in Bone Tumours and Osteoarthritis",subtitle:null,isOpenForSubmission:!1,hash:"ea4ec0d6ee01b88e264178886e3210ed",slug:"recent-advances-in-bone-tumours-and-osteoarthritis",bookSignature:"Hiran Amarasekera",coverURL:"https://cdn.intechopen.com/books/images_new/9500.jpg",editedByType:"Edited by",editors:[{id:"67634",title:"Dr.",name:"Hiran",surname:"Amarasekera",slug:"hiran-amarasekera",fullName:"Hiran Amarasekera"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"1591",title:"Infrared Spectroscopy",subtitle:"Materials Science, Engineering and Technology",isOpenForSubmission:!1,hash:"99b4b7b71a8caeb693ed762b40b017f4",slug:"infrared-spectroscopy-materials-science-engineering-and-technology",bookSignature:"Theophile Theophanides",coverURL:"https://cdn.intechopen.com/books/images_new/1591.jpg",editedByType:"Edited by",editors:[{id:"37194",title:"Dr.",name:"Theophile",surname:"Theophanides",slug:"theophile-theophanides",fullName:"Theophile Theophanides"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"3161",title:"Frontiers in Guided Wave Optics and Optoelectronics",subtitle:null,isOpenForSubmission:!1,hash:"deb44e9c99f82bbce1083abea743146c",slug:"frontiers-in-guided-wave-optics-and-optoelectronics",bookSignature:"Bishnu Pal",coverURL:"https://cdn.intechopen.com/books/images_new/3161.jpg",editedByType:"Edited by",editors:[{id:"4782",title:"Prof.",name:"Bishnu",surname:"Pal",slug:"bishnu-pal",fullName:"Bishnu Pal"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"371",title:"Abiotic Stress in Plants",subtitle:"Mechanisms and Adaptations",isOpenForSubmission:!1,hash:"588466f487e307619849d72389178a74",slug:"abiotic-stress-in-plants-mechanisms-and-adaptations",bookSignature:"Arun Shanker and B. Venkateswarlu",coverURL:"https://cdn.intechopen.com/books/images_new/371.jpg",editedByType:"Edited by",editors:[{id:"58592",title:"Dr.",name:"Arun",surname:"Shanker",slug:"arun-shanker",fullName:"Arun Shanker"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"3092",title:"Anopheles mosquitoes",subtitle:"New insights into malaria vectors",isOpenForSubmission:!1,hash:"c9e622485316d5e296288bf24d2b0d64",slug:"anopheles-mosquitoes-new-insights-into-malaria-vectors",bookSignature:"Sylvie Manguin",coverURL:"https://cdn.intechopen.com/books/images_new/3092.jpg",editedByType:"Edited by",editors:[{id:"50017",title:"Prof.",name:"Sylvie",surname:"Manguin",slug:"sylvie-manguin",fullName:"Sylvie Manguin"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"72",title:"Ionic Liquids",subtitle:"Theory, Properties, New Approaches",isOpenForSubmission:!1,hash:"d94ffa3cfa10505e3b1d676d46fcd3f5",slug:"ionic-liquids-theory-properties-new-approaches",bookSignature:"Alexander Kokorin",coverURL:"https://cdn.intechopen.com/books/images_new/72.jpg",editedByType:"Edited by",editors:[{id:"19816",title:"Prof.",name:"Alexander",surname:"Kokorin",slug:"alexander-kokorin",fullName:"Alexander Kokorin"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"2270",title:"Fourier Transform",subtitle:"Materials Analysis",isOpenForSubmission:!1,hash:"5e094b066da527193e878e160b4772af",slug:"fourier-transform-materials-analysis",bookSignature:"Salih Mohammed Salih",coverURL:"https://cdn.intechopen.com/books/images_new/2270.jpg",editedByType:"Edited by",editors:[{id:"111691",title:"Dr.Ing.",name:"Salih",surname:"Salih",slug:"salih-salih",fullName:"Salih Salih"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"117",title:"Artificial Neural Networks",subtitle:"Methodological Advances and Biomedical Applications",isOpenForSubmission:!1,hash:null,slug:"artificial-neural-networks-methodological-advances-and-biomedical-applications",bookSignature:"Kenji Suzuki",coverURL:"https://cdn.intechopen.com/books/images_new/117.jpg",editedByType:"Edited by",editors:[{id:"3095",title:"Prof.",name:"Kenji",surname:"Suzuki",slug:"kenji-suzuki",fullName:"Kenji Suzuki"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"3828",title:"Application of Nanotechnology in Drug Delivery",subtitle:null,isOpenForSubmission:!1,hash:"51a27e7adbfafcfedb6e9683f209cba4",slug:"application-of-nanotechnology-in-drug-delivery",bookSignature:"Ali Demir Sezer",coverURL:"https://cdn.intechopen.com/books/images_new/3828.jpg",editedByType:"Edited by",editors:[{id:"62389",title:"PhD.",name:"Ali Demir",surname:"Sezer",slug:"ali-demir-sezer",fullName:"Ali Demir Sezer"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}}]},chapter:{item:{type:"chapter",id:"73144",title:"Risk and Economic Analysis Methods of Commercial Aero Engines",doi:"10.5772/intechopen.93593",slug:"risk-and-economic-analysis-methods-of-commercial-aero-engines",body:'\nSafety is one of the main characteristics of all human activities. In particular, safety issues are principally acute in activities and industries that are considered dangerous. Air transport may be regarded as falling within this category, as failures of aviation-related equipment, flight support services and human factors-specific errors increase the likelihood and the potential of a disaster, which in turn yields financial losses. At the same time, losses from catastrophes in civil aviation are significantly less than in many other hazardous industries [1]. It may be stated that this level is attained due to continuous investment in methods and techniques as well as maintaining high reliability levels, which cover the entire organization. Today, the available risks influencing activity of the developed economic conditions, it is necessary to have the effective tools for risk and economic analysis. This equally includes aviation industry as well as enterprises operating aircraft equipment. One of such tools is risk analysis and economic analysis [2, 3, 4, 5].
\nAs stated by Cruse et al. [6], the way in which organizations such as Pratt and Whitney and Rolls-Royce find that the safe life of an aircraft engine depends on the design. The safety factor is applied in order to improve various configurations so as to empower safety. In order for equipment manufacturers to increase the associated safety level of their products, the number of flight cycles is determined. Different problems have prompted investigating the manageability of an aircraft’s engine life. Indeed, since 1984, resistance to damage has been a vital part of the ENgine Structural Integrity Program (ENSIP) contained in MIL-STD-1783. Currently, there is a program in the U.S. that uses probabilistic methods for gas turbine engines in ENSIP.
\nTo reproduce the probability estimates important for hazard or failure assessment, various computing strategies are used, including Monte Carlo simulation. Monte Carlo simulation reproductions have been included in the probabilistic study, as they tend to be used in failure analysis and can give high accuracy. This strategy has been used in numerous aviation-specific electronics and hazard assessment schemes. The disadvantages of this methodology are the enormous estimated time and the dependence of the measured estimate on the size of the sample.
\nEconomic analysis of aircraft and its components is one of the most important functions of airline management, the implementation of which is necessary to ensure its effective operation. As a matter of fact, economic analysis is known to represent numerous methods of economic theory. As such, economic analysis of aircraft and its components can be defined as an application of the theoretical foundations of the economy of the airline company and analytical sections of accounting to justify management-specific decisions.
\nThis chapter will consider methods of risk analysis and economic analysis of one of the most important components of a commercial aircraft - the power plant or engine.
\nTo improve the efficiency and objectivity of risk analysis and to ensure comparability with other risk analysis outcomes, the following general rules should be observed. The risk analysis process should follow the following steps:
Defining the scope of application
Hazard identification and preliminary impact assessment
Evaluation of the risk value
Verification of the analysis results
Documentary substantiation;
Adjustment of the results of the analysis taking into account the latest data.
This process is shown in Figure 1. Risk assessment includes frequency analysis and consequence analysis. While Figure 1 shows the documentation as a separate unit, it is developed at each stage of the process. Depending on the application, only certain elements of the process presented are considered. For example, in some cases it may not be necessary to go beyond the original hazard and impact analysis.
\nRisk analysis process.
A necessary requirement is a thorough knowledge of the system and the analysis methods used. If the results of a risk analysis for a similar system are available, they can be used as a reference. It is necessary to prove that the processes are similar and that the changes do not make significant differences in the results. Conclusions should be based on a systematic assessment of the changes and how they may affect the existing hazards.
\nA list of the most common methods is presented in Table 1. The list given in Table 1 is not exhaustive. The list of additional methods is presented in Table 2. Sometimes it may be necessary to use more than one analysis method.
\n\n | Method | \nDescription and application | \n
---|---|---|
1 | \nEvent tree analysis | \nA set of techniques for hazard identification and frequency analysis that uses an inductive approach to translate various initiating events into possible outcomes | \n
2 | \nFailure mode and effect analysis, as well as failure mode effects and criticality analysis | \nA set of methods for identifying the main sources of danger and frequency analysis, with the help of which all the emergency conditions of a given piece of equipment are analyzed for their influence on other components and on the system as a whole | \n
3 | \nFault tree analysis | \nA set of techniques for hazard identification and analysis of frequencies of an undesirable event, with the help of which all ways of its implementation are determined. A graphical image is used | \n
4 | \nStudy of hazards and related problems | \nA set of fundamental hazard identification techniques by which each part of the system is assessed to determine whether there may be deviations from the design intent and what consequences this may have | \n
5 | \nHuman factor analysis | \nThe set of methods consider influence of errors of the person on reliability | \n
6 | \nPreliminary hazard analysis | \nA set of techniques for hazard identification and frequency analysis used at an early stage of design to identify hazards and assess their criticality | \n
7 | \nStructural reliability scheme | \nA set of methods of frequency analysis, on the basis of which the system model and its reserves are created to assess the system reliability | \n
List of the most common methods used in risk analysis.
\n | Method | \nDescription and application | \n
---|---|---|
1 | \nClassification of risk groups by category | \nClassification of risk types by categories in order of priority of risk groups | \n
2 | \nInspection reports | \nInventory of generic hazardous substances and/or sources of potential accidents that need to be addressed. These can be used to assess compliance with laws and standards | \n
3 | \nGeneral failure analysis | \nA method designed to determine whether an accidental failure (accident) of a number of different parts or components within a system is possible and to evaluate its likely cumulative effect | \n
4 | \nImpact description models | \nAssessment of the impact of an event on people, property or the environment. Both simplified analytical approaches and complex computer models are used | \n
5 | \nDelphi’s method | \nThe method presents expert assessments that can provide frequency analysis, impact modeling and/or risk assessment | \n
6 | \nHazard indices | \nA set of hazard identification/assessment techniques that can be used to rank different system options and identify less hazardous options | \n
7 | \nMonte Carlo method and other modeling methods | \nA set of methods for frequency analysis that uses the system model to estimate variations in baseline conditions and assumptions | \n
8 | \nPaired comparisons | \nA way to assess and rank the universal risk by means of paired comparison | \n
9 | \nOperation data review | \nA set of techniques that can be used to identify potentially problematic areas and for frequency analysis based on accident data, reliability data, etc. | \n
10 | \nCovert process analysis | \nA method for identifying hidden processes and paths that could lead to unexpected events | \n
List of additional methods used in risk analysis.
Word pointer | \nRejection | \nPossible reasons | \nConsequences | \nAction required | \n
---|---|---|---|---|
No, not | \nNo expense | \nAbsence of submitted material | \nThe output of the molded polymer will be reduced | \nEnsure good communication with the operator Provide a low level signal on the installation tank | \n
The pump is faulty (many reasons) | \nThe output of the molded polymer will be reduced | \nProvide for a low level signal on the installation tank | \n||
A line is blocked or a control valve is erroneously closed or not closed | \nThe pump will overheat. | \nInstall a recirculation line on each pump | \n
HAZOP II indicator words.
The Event Tree Analysis, ETA is a set of quantitative or qualitative techniques that are used to identify possible outcomes of an initiating event and, if required, their probabilities. ETA is widely used for project-specific facilities that contribute to the reduction of accidents and identify sequences of events that, in turn, lead to certain consequences of the initiating event. Each event in the sequence is assumed to be either a failure or a fault.
\nNote that the probabilities in the event tree are conditional probabilities. For example, the probability of the sprinkler functioning is not a probability derived from tests under normal conditions but is a probability of functioning under fire conditions caused by an explosion.
\nThe ETA provides a relationship between the functioning (or failure) of a variety of systems and the hazardous event following the single initiating event. The ETA is very useful for identifying events that require further analysis using the FTA (i.e. the tip of the fault tree events). In order to be able to make a comprehensive risk assessment, all potential initiating events need to be identified. With this method, however, it is always possible to overlook some important initiating events. Moreover, in the case of event trees, we are only dealing with success and failure states. It is difficult to include delayed success or return events.
\nETA can be used both for hazard identification and for probabilistic evaluation of the sequence of events leading to hazardous situations.
\nFMEA is a predominantly qualitative method, although it can be presented in a quantitative form that systematically identifies the consequences of each individual component of an emergency condition. An indispensable feature in any FMEA is to consider each major component/particle of the system as to how it achieves the emergency state and how this affects the emergency state of the system. The analysis is usually descriptive and is organized in the form of a table or worksheet intended for information. The FMEA certainly refers to the emergency conditions of a system component, the causal factors and the effects of this condition on the system as a whole and presents them in a “user-friendly” form.
\nFMEA is a bottom-up approach and addresses the consequences of component failures in a “one-at-a-time” manner. This method is capable of processing sufficient data. In addition, the results can be easily double-checked by another person familiar with the system.
\nThe main disadvantages of the method are redundancy, the exclusion of recovery and repair activities and the focus on single component accidents.
\nFMEA can extend to performing what is called Failure Type, Function and Criticality Analysis (FMEA). In FMEA, each identified failure is ranked according to the likelihood of its occurrence and the severity of its consequences.
\nFMEA and FMESA provide input to analyses such as Fault Tree Analysis (a diagram analysis of all possible consequences of a failure or system crash). In addition to their application to system components, FMEA and FMECA can also be used in relation to human error; they can be used both for hazard identification and probability assessment (unless there is a limited level of redundancy in the system).
\nFault Tree Analysis, FTA is a set of qualitative or quantitative methods which are built into a logical chain and graphically presented those conditions and factors that may contribute to a certain undesirable event (called the top of events). Malfunctions or accidents identified in the “tree” can be events associated with damage to a component’s mechanical structure, personnel errors, or any other event that may cause an undesirable incident. Starting at the top of the events, possible causes or alarm states of the next, lower functional level of the system are identified. Subsequent step-by-step identification of undesired system operation in the direction of successively decreasing system levels leads to the desired system level, which is the alarm condition of the component. An example of a “fault tree” for an emergency generator is shown in Figure 2.
\nExample of a “fault tree.”
The FTA provides an approach that is highly systematic, but at the same time flexible enough to allow for the analysis of multiple factors, including human interactions and physical phenomena. The top-down approach, implicit in its methodology, focuses on those effects of a failure or accident that are directly related to the top of events. The FTA is particularly useful for analyzing systems with multiple areas of contact and interaction. Graphical representation makes it easy to understand the behavior of a system and the behavior of the factors included in it, but since the size of trees is often large, the processing of fault trees may require the use of computer systems. This feature also makes it difficult to check the trouble tree.
\nFTA can be used to identify hazards, although it is primarily used in risk assessment as a tool to assess the probability or frequency of faults and accidents.
\nHAZOP is a form of Failure Types and Consequences Analysis. HAZOP research was originally developed for the chemical industry. It is a procedure for detecting possible hazards across the entire facility. It is particularly useful for identifying unforeseen hazards in a facility due to lack of development information, or hazards that manifest themselves in existing facilities due to irregularities in their operation.
\nThe main tasks of the method are:
To compile a complete description of the object or process, including estimated design conditions;
To systematically check each part of the facility or process in order to identify ways in which deviations from the design intent may occur;
To decide whether hazards or problems associated with these deviations may occur.
The HAZOP research principles may be applied to technical facilities during their operation or at various design stages. HAZOP research performed during the initial design stage can be performed by the project manager.
\nThe most common form of HAZOP research is during the working design stage and is called HAZOP II research.
\nThe HAZOP II study has the following stages:
\nStage 1 – identification of the goals, objectives and scope of the study, for example, the identification of hazards characterized only by non-local effects or only local effects, areas of the industrial facility to be considered, etc.;
\nStage 2 – completing the HAZOP research team. This group should consist of designers and operators who have sufficient competence to assess the consequences of deviations from the conditions of the system operation;
\nStage 3 – gathering the necessary documentation, drawings and descriptions of the technological process. This includes graphs of the sequence of technological operations; drawings of pipelines and measuring equipment; technical specifications for equipment, pipelines and measuring equipment; logical diagrams of process control related technology; design diagrams; operation and maintenance methods; emergency response methods, etc.;
\nStage 4 – analysis of each main unit of equipment and all auxiliary equipment, pipelines and measuring equipment using documents collected at step 3. First of all, the purpose of the process design is determined; then, in relation to each line and unit of equipment with respect to such process variables as temperature, pressure, flow, level and chemical composition, the words-indicators are used (according to Table 3). (It is the author’s view that these indicator words stimulate individual thinking and encourage collective discussion);
\nStage 5 – document any deviation from the norm and the corresponding states. In addition, ways to detect and/or prevent deviations are identified. This documentation is usually indicated on HAZOP worksheets.
\nThe assessment is related to the impact of human factor, namely operators and maintenance personnel, on system operation and can be used to assess the effect of personnel errors on safety and productivity.
\nMany processes contain potential for personnel errors, especially when the time available for the operator to make decisions is limited. The likelihood that problems will develop in a negative way is often low. Sometimes actions from outside personnel’s jurisdiction are limited in their ability to prevent an initial fault progressing in the direction of an accident.
\nThe HRA identifies the various types of error actions that may occur, including the following:
Error by mistake, an oversight resulting in the failure to perform the required action;
An error of non-conformity, which may include:
A situation in which the action required is performed in a non-conforming manner;
An action performed with too much or too little force or without the required accuracy;
An action performed at a time not appropriate for it;
An action (or actions) performed in an incorrect order;
An extra action, an unnecessary action performed instead of or in addition to the required action.
The result of HRA identifies actions that can re-create previous errors.
\nThe HRA methodology is a mixed discipline involving researchers and practitioners who are typically specialists in either the theory and practice of reliability or psychology and human factors.
\nThe importance of HRA has been illustrated by various accidents in which critical human errors have contributed to a catastrophic sequence of events. Such accidents are a warning against risk assessments that focus exclusively on the mechanical design and software in the system. They illustrate the risk of ignoring human error. Moreover, HRAs are useful in considering errors that reduce productivity and in identifying the ways in which these errors and other faults (mechanical design and software) can be “replicated” by people, operators and maintenance personnel.
\nThe HRA can include the following steps: (1) task analysis; (2) identification of personnel error; (3) quantitative determination of the impact of the human factor on reliability.
\nThe task analysis and personnel error detection should be started at the concept stage and the early stages of design and development. They should be updated at later stages of the system development.
\nThe purpose of the task analysis in the HRA process is to describe and characterize the task to be analyzed in detail in order to identify human error and/or quantify the impact on human reliability. The task analysis can also be performed for other purposes, such as evaluating the person’s interaction with the machine or planning a procedure.
\nAt this stage, possible errors in the task are identified and described. The identification of personnel error may include:
The detection of the possible consequences and causes of the erroneous actions
The proposal of measures to reduce the probability of the error,
The improvement regarding the prospects for correction and/or the reduction of the consequences of erroneous actions. Thus, HRA results provide a valuable contribution to risk management, even if no quantitative assessment is made.
The purpose of HRA is to assess the probability of correct execution of the task or the probability of erroneous actions. Some techniques may also include steps to assess the probability or frequency of certain sequences of unwanted events or undesirable outcomes.
\nPreliminary Hazard Analysis, PHA is an inductive method of analysis whose purpose is to identify hazards, hazardous situations and events that may harm a given activity, facility or system. It is most often used at an early stage of project development when there is little information on design details and working procedures, and it can often be a precursor to subsequent research. In addition, it may be useful where existing systems or prioritize hazards where circumstances prevent the use of a wider range of techniques.
\nWhen conducting PHA, a list of hazards and general hazards is developed by considering such characteristics as:
The materials used or produced and their ability to react;
The equipment used;
Environmental conditions;
Location scheme;
Areas of contact and interaction between system components, etc.
The implementation of this method concludes with the determination of the potential for an accident, a qualitative assessment of the magnitude of the possible harm or health damage that may have been caused, and the identification of possible corrective measures. The PHA must be adjusted at the design, manufacturing, and testing stages to detect, correct, and improve new hazards. The results obtained can be presented in various ways, such as tables and “trees.”
\nThe detection of hazard assumes a systematic check of the investigated system with the purpose of identification of type of present unrecoverable dangers and ways of their display. Statistical records of accidents and experience of previous risk analyses can provide a useful contribution to hazard identification processes. It should be recognized that there is an element of subjectivism in hazard thinking and that identified hazards may not always be exhaustive hazards that could pose a threat to the system. It is necessary that identified hazards are reviewed when new data are available. Hazard identification methods are broadly divided into three categories:
Comparative methods, examples of which are inspection sheets, hazard indices and operational data review;
Fundamental methods, which are constructed in such a way as to encourage a group of researchers to use a prediction in combination with their knowledge of the hazard identification task by asking a series of questions such as “what if …?”. Examples of this type of methodology are Hazard and Related Problem Research (HAZOP) and Failure Analysis (FMEA);
Methods of inductive approach, such as logic diagrams of possible consequences of a given event (“event tree” logic diagrams).
Other techniques can be used to improve hazard identification (and risk assessment capabilities) for certain problems. For example: hidden fault analysis, the Delphi method and human factor analysis.
\nRegardless of the techniques used, it is important that the overall hazard identification process pays due attention to the fact that human and organizational errors are significant factors in many accidents. It follows that accident scenarios involving human and organizational error should also be included in the hazard identification process, which should not focus exclusively on technical aspects.
\nEconomic analysis as a science is a system of specialized knowledge linked:
with the study of economic processes in their interrelation, formed under the influence of objective economic laws and factors of subjective order;
With scientific justification of business plans, and with objective assessment of their implementation;
With identification of positive and negative factors and quantitative measurement of their action;
With disclosure of trends and proportions of economic development, with recognition of unused intra-economic reserves;
Generalization of the best practices,
With the adoption of optimal management decisions.
Economic analysis of aircraft and its components is one of the most important functions of airline management, the implementation of which is necessary to ensure its effective operation. As a matter of fact, economic analysis is known to represent numerous methods of economic theory.
\nModern management theories determine the necessity of substantiation of all-important management decisions by means of analytical process called “rational problem solving”. This process, the analytical part of which is identical to economic analysis, includes the following seven stages:
\nThe method of analysis should mean the methods of investigation of the object of analysis, and the method of analysis acceptance - one or more mathematical or logical operations aimed at obtaining a specific result of analysis.
\nMathematical methods are objective, as they yield the same results when applied by different analysts. In complex analysis, these methods are usually combined. Thus, the type of a mathematical model is often chosen intuitively, and the model parameters are determined by methods of mathematical statistics.
\nMathematical models: mathematical economy models - theoretical and applied models - are widely used in the analysis. Theoretical models allow studying general properties of economy and its separate elements by deduction of conclusions from formal preconditions. They are important for understanding possible properties of the object of analysis. They are macroeconomic and microeconomic models, including models of firm theory and market theory. Applied models provide an opportunity to estimate parameters of functioning of a concrete economic object and to formulate specific recommendations for decision making. Applied models include, first of all, econometric models, which operate with numerical values of economic variables and allow statistically significant evaluation on the basis of available observations.
\nMathematical models, besides, are subdivided into equilibrium models, which describe steady-state conditions and are therefore called descriptive, and optimization models, which allow establishing optimal, i.e. the best parameters of the system according to a certain criterion. Static models that describe the object state at a particular moment or period of time and dynamic models that include interrelationships of variables in time are distinguished.
\nMethods of applied mathematical statistics - econometrics, should be used as much as possible first of all in the analysis, since almost all data used in economic analysis contain a random component. Note that the results obtained by statistical processing of data may differ in the degree of accuracy and probabilistic validity. Estimates can be considered reasonable if their probability and accuracy are determined, otherwise they may not be credible.
\nMultidimensional methods: These methods provide objective quantitative tools to investigate data similarity, proximity, grouping or classification. Data can be presented as a set of indicators, variables that characterize objects or a single object at different points in time, e.g., an enterprise in different years. Most methods are designed to reduce the number of variables and highlight the most important characteristics. The following methods underline the most important ones:
\nThe method of cluster analysis, which allows building a classification of several objects by combining them into groups or clusters, based on the criterion of minimum distance in space of certain indicators describing the objects, as well as the classification of objects by a given number of groups – clusters. Probabilistic justification of the clustering results can be obtained by discriminant analysis.
\nFactor analysis: variables, whose values provide statistical or accounting data, are often quite conditional for the object or phenomenon under study. They can only indirectly reflect its internal structure, driving forces or factors. The analyst is limited to the set of indicators traditionally used in accounting and statistics. If an unknown factor manifests itself in changes of several variables, there is a correlation between these variables. The number of independent, initially hidden factors that can be detected by factor analysis is often significantly less than the number of traditional indicators.
\nIn addition, there are two levels of use of expert judgments: quantitative, in which experts make estimates in the form of quantitative indicators, and qualitative, in which experts make comparative estimates, for example, “better and worse.”
\nComparison is a scientific method of knowledge, in the process of its unknown phenomenon; subjects are compared with already known, studied earlier cases, in order to determine common features or differences between them. By means of comparison the general and specific in the economic phenomena, changes of the objects under study, tendencies and lawfulness of their development are studied. Hence, the following evaluations in the area of economic analysis and comparisons are used for identifying observed problems and suggest a course of action(s):
Comparison of planned and actual indicators to assess the extent to which the plan has been implemented. This comparison allows the user to determine the extent to which the plan has been completed in a specific timeframe, such as a month, quarter, or year.
Comparing the actual indicators with the normative ones allows cost monitoring and promotes the implementation of resource saving technologies. The practice of analytical work also uses comparisons with approved norms (for example, consumption of materials, raw materials, energy, etc.). Such a comparison is necessary to identify savings or over-expenditure of resources for production, to assess the efficiency of their use during operation.
Comparison of actual indicators with those of previous years to determine trends in economic processes.
Comparison with the best results, i.e. with the best samples, best practices. New achievements of science and technology can be carried-out both within the framework of the enterprise under study and outside. Inside the enterprise the average level of indicators achieved in general is compared with indicators of advanced sites. This allows identifying best practices and new opportunities for production and operation.
Comparison of the indicators of the analyzed form with the average indicators of the zone/area to assess the results achieved and identified unused reserves.
Comparison of parallel and dynamic series to study the relationship of the studied indicators. This is used to identify and justify the form and direction of the relationship between different indicators. For this purpose the numbers, which characterize one of the indicators, should be placed in ascending or descending order and consider how in this connection other investigated indicators change: ascending or descending and to what extent.
Comparison of different variants of managerial decisions in order to choose the most optimal of them.
Comparison of the results of activity before and after the change of any factor is applied in the calculation of the influence of factors and calculation of reserves.
The following types of comparative analysis are also distinguished in the economic analysis: horizontal, vertical, trend, as well as one-dimensional and multi-dimensional.
Horizontal comparative analysis is used to determine the absolute and relative deviations of the actual level of the studied indicators from the basic (planned, past period, average level, scientific achievements and best practices).
With the help of vertical comparative analysis the structure of economic phenomena and processes is studied by calculating the specific weight of parts in general, the ratio of parts of the whole among themselves, as well as the impact of factors on the level of performance indicators by comparing their values before and after changing the relevant factor.
Trend analysis is used to study relative growth rates and growth of indicators over a number of years to the level of a base year, i.e. to study the dynamics series.
In one-dimensional comparative analysis comparisons are made on one or several indicators of one object or several objects on one indicator.
By means of the multi-dimensional comparative analysis the results of activity of several operating enterprises (divisions) are compared on a wide spectrum of indicators.
The sequence of performing factor analysis includes the following stages:
Selection of factors that determine the performance indicators under study and their systematization in order to ensure the capabilities of the system approach;
The establishment of modeling and transformation of the factor systems
Calculation of the influence of factors and assessment of the role of each of them in changing the value of the resultant indicator;
An important methodological issue in factor analysis is the determination of the relationship between factors and performance indicators: functional or stochastic, forward or backward, straight or curved. Here, theoretical and practical experience as well as methods of comparison of parallel and dynamic series is used in conjunction with analytical groups of initial information, graphic and others.
\nThe modeling of economic indicators (deterministic and stochastic) is also a complex methodological problem in factor analysis, the solution of which requires special knowledge and practical skills in this branch.
\nThe most important methodological aspect in economic analysis EA, is the calculation of the influence of factors on the value of effective indicators, for which the analysis uses a set of methods, the essence, name, scope of which and the procedure of calculation are considered in the following chapters.
\nFinally, the last stage of the factor analysis is the practical use of the factor model for calculation of reserves for the growth of the resultant index, for planning and forecasting its value in case of changes in the production situation.
\nAn increase in resource (durability), which is an integral part of reliability, accordingly, leads to an increase in the latter. Increasing reliability, as well as increasing resources (reliability component), requires a significant amount of work, significant cost and time. The past decades of aviation Gas Turbine Engines (GTEs) development have been marked by a continuous growth of resources: from several hundreds of hours to tens of thousands of hours.
\nWhen the engine resources did not exceed 1000 hours, there were no doubts about the economic expediency of their increase due to at least two circumstances: high expenses of the operating organizations and relatively small expenses for the works connected with the increase of resources (Figures 3 and 4).
\nGrowth of resources of engines AI-20 (1), AI-24 (2), AI-25 (3) on years of operation.
Growth of resources of engines with a large degree of dual circuit D-36 (1), D-18T (2), D436T1 (3).
A different situation occurs when justifying large resource values (>20,000 hours). On the one hand, the operating costs are already significantly reduced (operating costs per hour of motor operation), and with small operating costs, further reduction of the operating costs brings ever less economic benefit. In addition, in accordance with the law of the dwindling limit value, the operating costs may increase starting from a certain service life.
\nOn the other hand, an ever-increasing amount of effort is required to increase resources.
\nThere is an economically optimal resource value, at which the total cost of increasing the resource is the lowest (TOP 1).
\nThe introduction of electronic engine designers, the use of numerical methods and high-level models, application software packages (e.g. ANSYS), combined with the accumulated experience in the creation of aircraft GTEs and the high qualifications of engineering staff have allowed the development and successful application of calculation methods for resource determination.
\nIt has given the chance to lower expenses essentially and to reduce calendar terms of an establishment of resources. At the same time, the importance of an economically optimal resource to the right has shifted significantly [7] (Figure 5).
\nDependence of change in costs on the value of the engine resource.
For different engines, and even for the same engine installed on different aircraft, there will be different values of optimal service life, as operating costs may vary depending on the engine type, aircraft type, operating company, etc.
\nThe engine resource can be very large; however, it will be far from economic optimum. The indicator of optimum resource can serve as total value of expenses for 1 hour of established resource.
\nDeviation of a resource of the engine from economic optimum can be connected with special requirements to the engine, overlapping at designing. In this case, the efficiency of the design solutions used may “prove to be as efficient as possible under imposed constraints.”
\nThe desire to establish an economically optimal resource was one of the reasons why the notion of resource design appeared.
\nUnder resource designing of aviation GTEs, it is necessary to understand the durability details at a design stage of the engine. The full account of operating conditions is provided and optimization of a level of working parameters, indicators of effect and value of resource is made.
\nThe development of technical (indiscriminate) diagnostics, modularity of design, content usability of engines and accumulated experience of operation allowed to carry-out the operation of aviation GTEs on technical condition. The economic effect from the exploitation according to the technical condition is very high:
The number of spare parts is reduced by 20%;
The number of spare engines is reduced by half;
The cost of maintenance and repairs is reduced by approx. 25%.
The almost universal transition to maintenance-free operation, with the replacement of individual modules without removing the engines from the wing, has led to a review of the engine life as a whole.
\nFor a complex, multi-component system, the concept of engine life becomes conditional. The economic purpose of engine reconditioning during repairs and the cost per hour of a life cycle are of paramount importance. The economic viability of engine reconditioning depends on the cost of repair and the cost of replacing parts that limit the life cycle (Table 4).
\nRental no | \nWorking hours before renting, hour | \nTotal earnings, hour | \nThe cost of repair, $ | \nCost of parts to be replaced, $ | \n
---|---|---|---|---|
1 | \n8500 | \n8500 | \n800.000 | \n— | \n
2 | \n6500 | \n15.000 | \n900.000 | \n650.000 | \n
3 | \n6500 | \n21.500 | \n950.000 | \n410.000 | \n
4 | \n6500 | \n28.000 | \n950.000 | \n265.000 | \n
Costs of scheduled maintenance of the CFM56-3 engine with 23,500 lb thrust.
Using the data in Table 4, it is possible to determine repair costs per hour for a CFM56-3 engine with a thrust of 23,500 pounds (10,657 kG) using Eq. (1):
\nwhere \n
Adding all the costs in columns 4 and 5 of Table 4, dividing by the number of flight cycles (28,000 cycles) and duration of flight (1.4 hours), yields $125.64. Adding to cost of a new engine, attributed to 1 hour of operation, and the cost of fuel consumption for 1 hour of engine operation, results in the cost of 1 hour of the life cycle of the CFM56-3 engine (Eq. (2)).
\nwhere \n
For each engine, there is an optimum operating time on the wing (before repair). For example, for the PW4000 engine, the optimum wing life is 3500–4500 flight cycles.
\nThis is due to the ability to repair and rebuild the structure and properties of the fuel blades. Longer engine stay on the wing leads to a high degree of utilization of the blades. Therefore, it is very important to keep exact account of engine details operating time in hours and flight cycles. An error in the operating time can lead to a substantial increase in the cost of repairs.
\nPowder metallurgy, laser and micro-plasma welding methods are used in blade repairs. The limitations of the repair are related to cracks and thinning of the blade walls.
\nModifying the structure and properties of the blade, allows the same blades to be used for a longer period of time in the engine. This results in significant cost savings. Based on performed research and the associated data, the recovery and repair of 30,000 work blades can bring savings of up to $80,000.
\nResource of details is expedient to provide at designing so that replacement of basic details in operation was possible less. It is necessary to plan replacement of details (not concerning the basic), limiting a resource, by a combination of replacement with repair of engines (visit of workshop).
\nIn order to avoid forced removal of the engine from the wing due to the end of the service life of the main parts, most airlines operating GTE maintain a “service life balance” policy (minimum life of parts). The essence of the case is that the majority of parts that limit the life produce their life span in the range of 1500–3000 flight cycles from their limit life.
\nFor example, the front rotor shaft of a CF6-50 engine has a limit of 11,500 flight cycles but is likely to be disposed of after (9500–10,000) flight cycles (Table 5).
\n\n | Engine | \nCost of main parts, million $ | \nUnused resource remnants, cycle | \n
---|---|---|---|
1 | \nJT9D | \n2.1 | \n2000 | \n
2 | \nPW4000 | \n2.44 | \n2000–3300 | \n
3 | \nCF6-50 | \n2.1 | \n1400–2500 | \n
4 | \nCF6-80C2 | \n2,.7 | \n2000–2500 | \n
Costs and unused balances of resources of the main details of aero engines.
In this case, the cost of 1 hour of the engine’s life cycle is reduced, which increases the competitiveness of the engine.
\nIn addition to the planned reasons for removal (exhaustion of the reserve in terms of the temperature of exhaust gases, increase in the reserves of stability of the ATC, exhaustion of the service life of parts that limit the resource, etc.), a significant share is occupied by unplanned ones.
\nUnscheduled engine removals can make big corrections to the repair and replacement schemes of the parts that limit the service life. The number of unscheduled engine removals can be 50% of the total number of removals. For example, for the PW4000 family engines, unscheduled removals account for 35–45% of all removals. For CF6-50 engines the reason for 25% of removals is exhaust gas temperature exhaustion, other 25% of removals are caused by the necessity to replace the main parts, which have reached their end-of-life, and another 50% of removals are unplanned removals [8]. In order to increase the economic efficiency of aviation GTEs operation it is necessary:
To install the engine parts with minimum expenses;
To ensure optimal stay of the engine on the wing of the aircraft in a single operation;
Ensure the timely replacement of parts that limit the engine’s life (avoid early removal of the engine due to lack of service life of the main parts or exhaustion of gas reserves);
Accurately determine the current damageability of parts in hours and cycles depending on the operating conditions (automated hours and cycles);
Quickly determine the scope of work and necessary parts replacement during unscheduled engine stripping;
Taking into account unplanned surveys to correct the scope of work for subsequent engine reconditioning, and remain the engine on the wing, etc.
It is most convenient to perform the above-mentioned works using ground automated systems of engine operation monitoring. One of the essential elements of such systems is the algorithms of calculating the developed resource.
\nThe conducted analysis of aviation GTE resources allows drawing the following conclusions:
There is an economically optimal engine resource for the given operation conditions.
Economically optimal engine life can change significantly with changes in the cost of life.
To improve the economics of engine operation, ground-based automated engine performance monitoring systems should be used.
This chapter is the result of the study of a number of special disciplines, such as risk analysis and economic analysis of commercial aero engines during aircraft operation. Risk analysis includes risk assessment and methods to reduce risks or reduce adverse effects associated with it. The methods for risk analysis have been provided, including ETA, FMEA, FTA, HAZOP and PHA.
\nFurthermore, Economical analysis is a scientific way of understanding the essence of economic phenomena and processes, based on dividing them into its constituent parts and studying the variety of relationships and dependencies aimed at improving its work through the development and implementation of optimal solutions. The purpose of the economic analysis is to give management a picture of the actual state, and for persons who are not directly working with it, but are interested in its financial condition, the information necessary for an impartial judgment.
\nAviation engineering as a commodity has its specificity. If one considers an aircraft as a whole, the aircraft operation efficiency is defined by perfection of the power plant. The engine may appear on the market as an independent product with a market price. But it must be taken into account that the aircraft engine is a subsystem of the aircraft, so its economic assessment should be carried out, if possible, taking into account the characteristics of the aircraft and its specifics of operation, which is a difficult task. Still, this is a necessary procedure, especially in the case of economic evaluation.
\nThe world’s needs for effective heat transfer devices/mechanisms are increasing so as to minimize heat losses, minimize systems cost, enhance heat removal and transportation as well as to increase lifespan of some devices. In some instances, heat is required to be removed from a system (like solar photovoltaic, electrical devices, turbine blades, etc.) in order to keep it at a certain operation temperature, while in other cases, it is required to be transferred to a certain region to keep it at high temperature. Some elements/metals such as copper and aluminium are found to be good conductors of heat as they transfer heat effectively from one region to another. Their ability to transfer heat effectively is due to their molecular arrangements and type of bonds between their molecules. Various systems such as aircraft, electronics, heat exchangers, solar collectors, etc. require effective means of heat transfer. One of the devices recognized as effective means of heat transfer is heat pipe, whose idea was introduced by Graugler in 1942, but its first unit was invented by Grover in 1962; then, its important properties were studied and identified, and its development started [1]. Hence, with the growing need for efficient heat transfer devices, interest in the use of heat pipes for various applications is increasing due to the roles they play in improving the thermal performance of solar collectors and heat exchangers particularly in energy savings and increasing efficiency of the systems.
\nHeat pipe is an efficient two-phase heat transfer device which uses latent heat of fluids to transfer energy from one place to another by means of simultaneous evaporation and condensation in a sealed container. It consists of evaporator and condenser sections with or without adiabatic section in between them. Depending on the type, heat pipe may have wick materials on its internal surface where the simultaneous evaporation and condensation take place in the wick structure. In such types of heat pipe, evaporator section can be placed at the top, since the wick structure can return the condensate from the condenser section against gravity. Hence, in a wick heat pipe, the condensed liquid is returned to the evaporator by capillary effects with the assistance of the wick materials as shown in Figure 1.
\nOperation of wick heat pipe [
However, many applications do not require inserting wick material on the inner surface of the pipe, because the condenser section can be placed at the top, so that the condensed liquid returns to the evaporator by gravity. This type of wickless heat pipe is called thermosyphon as shown in Figure 2 Hence, for thermosyphon, the condenser must be above the evaporator, while for the wick heat pipe, the capillary forces in the wick ensure the condensate returns to the evaporator regardless of its position.
\nOperation of thermosyphon [
Heat pipes consist of sealed vessel usually made from aluminium or copper with or without wick material lined on the inner surface and working fluid charged under a vacuum condition. It is made up of two main sections: evaporator, where the working fluid absorbs heat, and condenser, where the working fluid rejects heat (Figures 1 and 2). As heat is added to the working fluid in the evaporator section, it evaporates into vapour when it reaches its saturation temperature. It rises to the condenser with the assistance of buoyancy force and due to the vapour pressure difference between the two sections. The liquid condenses by giving out its enthalpy to the cooling water in the condenser section and returns back to the evaporator for another cycle.
\nHeat pipes offer advantages over other heat transfer devices used for various applications in engineering systems. The technology has undergone rapid development due to their operational advantages [3]. Some of these advantages include:
High thermal conductivity: In terms of heat transfer, heat pipes are better than the best conductor; hence, they are referred to as ‘superconductors’.
Light weight.
Efficient heat transfer.
Flexibility in design.
Isothermal operation.
Tolerance to freezing, shock and vibration.
Low cost.
There are different types of heat pipes, classified based on [4]:
Nature of fluid circulation, such as capillary driven, rotating heat pipes, flat plate, two-phase close thermosyphon, etc.
Control of heat transfer: They are ‘controlled heat pipes’, such as variable-conductive, thermal switch and thermal diode.
Electrostatics-driven heat pipes such as electro hydrodynamic heat pipe.
Osmosis-driven heat pipe such as osmotic heat pipe.
Others including inverse, micro, reciprocating, cryogenic, capillary pumped loop heat pipes, etc.
Due to the advantages of heat pipes, the technology found its applications in many fields of engineering such as:
Spacecraft thermal control [5]: the first test of heat pipe in space was in 1967 [6] and the first heat pipe used for satellite thermal control was on GEOS-B launched from Vanderburgh Air force Base in 1968 [7].
Component cooling, temperature control and radiator design in satellites. Other applications include moderator cooling, removal of heat from the reactor at emitter temperature and elimination of troublesome thermal gradients along the emitter and collector in spacecraft.
Heat pipes for dehumidification and air conditioning: The heat pipe is designed to have one section in the warm incoming stream and the other in the cold outgoing stream. By transferring heat from the warm return air to the cold supply air, the heat pipes create the double effect of pre-cooling the air before it goes to the evaporator and then re-heating it immediately.
Heat exchangers [8].
Developed thermosyphon heat pipe solar collector [
The wick and wickless (thermosyphon) heat pipes have many features in common in their construction, operation and applications. However, they differ in some aspects such as:
Wick material: unlike in thermosyphon, wick materials are lined on the inner parts of the wick heat pipe. This enables the return of the condensed liquid even against gravity.
Orientation of the pipes: the condenser section of the thermosyphon must be located at the top of the evaporator because the return of the condensate is basically by gravity, while in the case of the wick heat pipe, the evaporator can be placed at the top because the return of the condensate is based on the capillary effects due to the presence of the wick materials.
Need of adiabatic section: thermosyphon may or may not have adiabatic section whereas most of the wick heat pipes have it, as to separate the evaporation and condensing sections.
When working fluid is charged into the sealed container, it forms a liquid pool (in case of thermosyphon) while in case of wick heat pipe, it saturates the wick materials.
This is a natural fluid circulation heat pipe which has no wick material presence. It is a simple heat pipe consisting of a sealed vessel charged with working fluid under a vacuum condition. It is made up of evaporator and condenser sections, sometimes with adiabatic section in between them. The vessel is usually made from aluminium or copper to facilitate high conduction of heat. Unlike wick heat pipe, the condenser of thermosyphon must be at the top, for the condensed liquid to return to the evaporator under gravity. Furthermore, some applications of thermosyphon require that the pipe be tilted to an angle from the horizontal for it to have maximum exposure to solar radiation [9, 14, 15, 16].
\nThermosyphon is a vessel closed at both ends and attached with a small charging pipe placed at one of the ends. The air in the vessel is evacuated creating a vacuum, then charged with working fluid through the charging pipe. The pipe is usually divided into the following sections:
Evaporator, where heat is supplied to the working fluid.
Adiabatic section (optional): space between evaporator and condenser, where no heat or cooling is applied.
Condenser, where the vapour from the evaporator section of thermosyphon heat pipe is condensed usually by cooling water flowing through a water jacket.
Insulation: the evaporator section is insulated to minimize heat losses.
The materials for the manufacturing of thermosyphon are carefully selected to ensure its effective performance. Other considerations are the type and the quantity of working fluid to be charged into the pipe.
\nThe working principles of thermosyphon are similar to that of the wick heat pipe, but differ in the process of the return of the condensed liquid in the condenser due to the absence of wick structure. For proper operation of thermosyphon, the condenser is placed at the top of the evaporator so that the condensed liquid will return to the evaporator by gravity. Figures 4 and 5 show a schematic diagram and a model of a typical thermosyphon (constructed in the University of Birmingham, UK) with heat supplied by coil of wire and heat rejected to the flowing water in the water jacket provided on the condenser section [17]. However, in some operation set ups, the heat can be supplied by hot water surrounding the evaporator of the pipe.
\nDimensions of a typical thermosyphon with water manifold [
3D view of a typical thermosyphon pipe.
Heat pipe (with or without wick materials) operates within certain limits which are shown in Figure 6. For the heat pipe to operate, the maximum capillary pumping pressure must be greater than the total pressure drop; thus:
\nLimitation of heat pipe for heat transport.
The pressure drop is the sum of the following:
\n\n\n
\n\n
\n\n
If condition in Eq. (1) is not met (capillary limit), then the wick materials will dry out and the pipe will not operate. Detailed discussions on the heat pipe limits (shown in Figure 6) are available in heat pipe books, which can be referred.
\nApart from the general advantages of heat pipe, thermosyphon has other advantages over wick heat pipe, some of which are listed below:
Relative low-temperature difference between the heat source and heat sink
More compactness
High durability and reliability
Cost-effectiveness
Less weight due to the absence of wick materials
Simplicity in construction
The performance of thermosyphon under different conditions is evaluated based on the overall thermal resistance \n
where \n
However, the performance of the thermosyphon can also be calculated as the ratio of the heat transfer to the cooling water to the heat input as [18]:
\nThe rate of heat transfer to the cooling water, \n
where \n
Two approaches are usually employed in the performance characterization of thermosyphon, namely:
Experimental
Numerical
The thermosyphon heat pipe can be experimentally characterized and the effects of some parameters on its performance evaluated. Figures 7 and 8 show a schematic diagram and picture of a typical test rig for the performance characterization of thermosyphon constructed at the University of Birmingham, UK, for analyzing the performance of a two-phase closed thermosyphon. It consists of a 0.4-m-long two-phase closed thermosyphon heat pipe, heating coil, water jacket and other instrumentations.
\nSchematic diagram of the experimental test rig for thermosyphon characterization [
Picture of the heat transfer characterization of thermosyphon test rig [
The heat can be supplied by hot water circulating around the evaporator or by electric power supply. In Figures 6 and 7, the evaporator section is wrapped evenly with electric wire with electric energy supplied and controlled by TSx1820P Programmable DC PSU 18 V/20A power regulator to provide the heat required for boiling the working fluid inside the pipe. A multimeter is used for measuring the voltage input which is connected close to the pipe to account for the voltage drop while the current was read from the power regulator. The evaporator section is also insulated with 25-mm-thick pipe insulator to reduce the heat loss to the ambient environment (Figure 8). For measuring the temperature distribution along the pipe, 12 surface thermocouples were placed at different locations on the test pipe; 4 on the evaporator wall (at 0.02, 0.07, 0.12 and 0.17 m from the tip of the evaporator) and 2 on the condenser wall at 0.25 and 0.35 m as shown in the figures. The electric wires were wrapped in such way that they are not directly on the thermocouples so as to not affect their readings. Two probe thermocouples were installed at the inlet and outlet of the manifold to measure the temperatures of the cooling water. Three other thermocouples were used on the water jacket and one on the insulator to measure the effectiveness of the insulation and the jacket. All the readings were sent to Pico TC-08 data loggers connected to a PC.
\nThe test rig has to be provided with different measuring devices of temperature, water flow rate, heat (power) input and angular orientation to enable investigating the flow and heat transfer characteristics of the selected thermosyphon. The instruments include:
\n□ Thermocouples, both surface and probe types.
\n□ Flow meter.
\n□ Electric power regulator (or hot water supply in some cases).
\n□ Data logger.
\n□ Angular measurement instrument such as protractor
\nThe instruments are calibrated against standard devices and error analysis and uncertainties of their measurements are evaluated.
\nThe test facility was completed and ready for investigations when all the parts were connected and water circulation system was checked for possible leakages. The operating conditions are set based on the type of the investigation to be carried out. However, in all the cases, the system is allowed to run and stabilize before readings are taken. Preliminary tests are required to determine the time when the system reaches steady state. Certain number of readings are set to be taken for each boundary condition at a set interval of time (usually in seconds). The reading recorded includes the temperatures, flow rates, voltage and current. Various investigations can be carried out using the test rig such as the effects of heat inputs, cooling water flow rate, inclination effects of the pipe, fill ratio, etc. Detailed procedure for each case depends on the type of the investigation to be carried out.
\nTo enable several investigations on many parameters affecting the performance of thermosyphon with different boundary conditions, numerical approach is usually employed. This is because experimental approach requires more time, energy and huge investment, to investigate many cases under different boundary conditions. There are two numerical approaches that are employed in modelling multiphase flows, namely the Euler-Euler and Euler-Lagrange approaches. In the Euler-Euler approach, the several phases are considered as interpenetrating continua mathematically in which each phase a volume is occupied only without sharing with other phases, while Euler-Lagrange approach utilizes Navier-Stokes equations that are solved for the fluid phase with several numbers of particles tracked in order to solve the dispersed phase. It should be noted that this approach cannot be adopted for applications in which volume fraction is important, especially for the secondary phase. Hence, the Euler-Euler approach is usually used in modelling two-phase closed thermosyphon operations.
\nUsing Euler-Euler approach, three multiphase models are available in ANSYS Fluent:
The Eulerian model
The Mixture model
The Volume of Fluid (VOF) model
The mixture model deals with modelling of sedimentation, bubbly flows, particle-laden flows, etc. While applications such as fluidized beds, particle suspension, risers are modelled using Eulerian approach, on the other hand, liquid-gas tracking under steady or transient, free-surface flows, large bubble in liquid are modelled using the VOF approach.
\nNumerical modelling like computational fluid dynamic analysis (CFD) is an alternative to experimental approach, whereby several studies can be carried out with small investment. In CFD, a set of discretized equations are solved with the help of computer to get an approximate solution [20]. CFD analysis can be carried out on the flow and heat transfer characteristics of a thermosyphon heat pipe in both vertical and inclined orientations using a commercial ANSYS Fluent or any software that can model the simultaneous evaporation and condensation processes taking place in a thermosyphon heat pipe. However, some approaches like volume of fluid (VOF) in ANSYS Fluent require the user to add a user-defined function (UDF) to the modelling process.
\nThe first step in solving any multiphase problem is identifying the suitable multiphase regime which represents the flow needed to be modelled. In this chapter, emphases is put more on the VOF model.
\nFor building a model for simulating the flow and heat transfer characteristics of thermosyphon, a researcher is required to have a good knowledge of the theory (physics) behind the processes. The processes involved in the CFD modelling of the performance of thermosyphon using volume of fluid (VOF) approach in ANSYS Fluent can be summarized as follows:
Generation of the pipe geometry (model).
Meshing of the model: different meshes of different properties (number of cells, faces, quality, etc.) are required.
Carrying out a grid independence test: this is done to find out the situation whereby the result is independent of the mesh configuration and to select the configuration which will give less computational time.
Importing the selected meshed file for the investigations into the ANSYS Fluent.
Attaching the user-defined function (UDF); this depends on the modelling approach selected.
Modelling and simulation set up, which includes.
Defining the boundary conditions.
Setting the thermophysical properties of the materials involved such as thermal conductivity, material properties, density, specific heat capacity, viscosity, etc.
Defining of the solution method and convergence.
Running the simulation and processing of the results.
Validation of the model: to enable validation of the developed model, the boundary conditions and other definitions are made exactly as those set in the experiment.
Once the model is validated with the experimental results, then it can be used for further investigations.
Considerable experimental research works were published on the investigation of the effects of parameters like the geometry, working fluid, fill factor and inclination on the thermosyphon heat pipe performance [21, 22, 23, 24, 25]. Hence, apart from the material of the thermosyphon, other important parameters affect its performance, such as:
Type of working fluid charged: The common liquid used in thermosyphon is water due to its availability, low cost, safety, etc. Below are some of the prime requirements for a liquid to be used in heat pipe:
Compatibility with wick and wall materials
Good thermal stability
Wettability of wick and wall materials: it is necessary for the working fluid to wet the wick and the container material, that is contact angle should be zero or very small
High latent heat: a high latent heat of vaporisation is desirable in order to transfer large amounts of heat with minimum fluid flow, and hence to maintain low pressure drops within the heat pipe
High thermal conductivity: the thermal conductivity of the working fluid should preferably be high in order to minimize the radial temperature gradient and to reduce the possibility of nucleate boiling at the wick or wall surface
Low liquid and vapour viscosities: the resistance to fluid flow will be minimized by choosing fluids with low values of vapor and liquid viscosities
High surface tension: in heat pipe design, a high value of surface tension is desirable in order to enable the heat pipe to operate against gravity and to generate a high capillary driving force
Acceptable freezing or pour point
The selection of the working fluid must be based on thermodynamic considerations which are concerned with the various limitations to heat flow occurring within the heat pipe, like viscous, sonic, capillary, entrainment and nucleate boiling levels.
\nSome common liquids used in heat pipe include water, acetone, ethanol, ammonia, nitrogen and methanol. However, recent researches have shown potentials of using other liquids alone or mixed with water like nanofluids [26, 27, 28].
\nII.Quantity of the working fluid charged: the quantity of the liquid charged in relation to the volume of the evaporator, called fill ratio, FR or liquid ratio, plays a vital role in the performance of thermosyphon. Fill ratio is defined as the ratio of volume of the working fluid in an unheated pipe, \n
The quantity of the fluid to be charged has to be properly selected, which depends on the intended applications, as insufficient amount of fluid causes dry out while excessive amount reduces performance and increases the cost of the pipe. FR of a thermosyphon should be between 40 and 60% for vertical pipes and between 60 and 80% for inclined pipes [4, 29] . For example, Emami et al. [30] and Asgar [18] obtained 45 and 50% as best FR respectively.
\nIII.Heat input: The amount of heat supplied in the evaporator affects the performance of the thermosyphon depending on other factors such as size, fill ratio, its geometry and operating limits. Experimental results have shown that the performance of the thermosyphon increases with the increase in heat input up to their operating limits. It increases with increase between 350 and 500 W, but it decreases when the heat input is above 500 W [18] . But for Abdullahi et al. [19], the performance of the pipe increases as the heat input increases from 20 to 81.69 W, but it tends to decrease as more heat is supplied, showing the limit of this pipe has been reached under these operating conditions (Figure 9). Hence, the trend of the performance of the thermosyphon (based on the amount of the heat input in the evaporator section) depends on its operating limits. At low heat input, the vapour generated from the evaporator section is small, so there will be significant dry areas in the condenser section; hence, heat transfer is largely by free convection. As the heat is gradually increased, more vapour will rise to the condenser section, there will be high condensation rate on the condenser wall and the dominant heat transfer mechanism will be condensation. But at certain high heat input, thick layer of liquid can be formed on the wall of the pipe causing high thermal resistance and hence lower the heat transfer to the cooling water, hence reduction of performance.
\nPerformance of thermosyphon aligned vertically at different heat inputs [
IV.Inclination angle: since the condenser of thermosyphon must be at the top with the evaporator at the bottom for the condensate to return, this shows that the pipe can be inclined at any angle other than 90°. Regarding the effect of inclination angle on heat pipe performance, conflicting experimental results were reported like angles between 15 and 60° [24], between 40 and 45° [25] and 60° [30] gave the best performance. Others reported higher angles like 90° [31] and 83° [32] as the best performing angles while few reported that inclination angle has no effect [33]. The possible reasons for the contradicting results are the complex nature of the processes taking place in thermosyphon operations and various parameters affecting its performance. Furthermore, those researches are only experimental and considered a small range of inclination angles. With the contradictory experimental results in the literature and lack of, or limited, numerical studies on the effect of inclination, Abdullahi et al. [19] addressed these issues through the development of a CFD model that studied the effects of inclination angles (10–90°) and experimentally validated the model. Experimental and numerical results showed that increasing the inclination angle will improve the thermosyphon heat pipe performance to reach its maximum value at 90°, but this effect decreases as the heat input increases [19] (Figure 10).
\nVariation of the thermosyphon performance with inclination angle at different heat inputs [
V.Flow rate of cooling water: the rate at which cooling water is passing in the water jacket around the condenser of a thermosyphon affects its performance. As the rate of the heat removal from the vapour increases, more condensate returns to the evaporator for another cycle. The effect of cooling water flow rate at constant heat input was investigated on the performance of thermosyphon heat pipe [19]. The heat input was fixed at 101 W while five different flow rates ranging from 0.00156 to 0.00611 kg/s were investigated. Temperature and the flow rate readings were recorded for each run and the effects of the cooling water flow rate were evaluated based on the overall thermal resistance, rate of heat transfer to the cooling water, outlet temperature of cooling water, performance of the thermosyphon, etc. The results from such work have shown that the performance of the pipe in terms of heat transfer to the cooling water increases with the increase in the cooling water flow rate. This is due to the mass flow of the cooling water which results in the enhancement of the rate of heat transfer from the pipe wall to the cooling water and subsequent increase in the efficiency.
\nIn addition to the general advantages of heat pipes, thermosyphon type is found to be highly durable, reliable and cost-effective, which make them useful for various applications, such as:
Solar heating of building [16].
Liquid circulation: thermosyphon system is used for circulating liquids and volatile gases in heating and cooling systems such as water heaters, furnaces and boilers. It simplifies transfer of liquid or gas without using conventional pump which adds cost and complexity to the system.
Cooling applications: thermosyphon is used in cooling of turbine blades, transformers, electronics, internal combustion engines and nuclear reactors [34, 35]. This is due to their ability to dissipate and transfer large amount of energy from small area without any significant loss.
Aircraft cooling: due to their light weight, thermosyphon pipes are used in cooling of aircraft and spacecraft.
Receiver in solar collector (solar systems): thermosyphon is proved to be a good choice as a receiver for solar concentration systems due to its advantages stated [36, 37] as shown in Figures 3 and 11.
\nDeveloped compound parabolic collector with thermosyphon as receiver [
Several parameters affect the operation of thermosyphon such as fill ratio, working fluid, inclination, geometry, heat input, cooling water flow rate, etc. Experimental and numerical (CFD) studies are usually carried out to enable the investigation of the effects of some of these parameters on the performance of thermosyphon heat pipe for use in various engineering applications. Investigations on the effects of heat input, fill ratio, flow rate of cooling water on the temperature distributions on the wall of the pipe, overall thermal resistance and overall performance of the pipe at vertical orientation were shown to be possible both experimentally and using CFD. Also, the effect of inclination angle of thermosyphon on those parameters was successfully added in the Fluent. Hence, the chapter has shown that volume of fluid (VOF) model’s approach in ANSYS together with UDF and other software can fully simulate the complex evaporation and condensation processes taking place in thermosyphon for both vertical and inclined orientations.
\nIntechOpen offers several publishing options to researchers and research groups looking for a professional partner with a wide, international reach. Our publishing options cover the breadth of scientific publications and ensure an appropriate outlet for your research.
",metaTitle:"Why publish with IntechOpen?",metaDescription:"IntechOpen offers publishing options to researchers and research groups looking for a professional partner with a wide, international reach. Our publishing options cover the breadth of scientific publications and ensure an appropriate outlet for your research.",metaKeywords:null,canonicalURL:"/page/why-publish-with-intechopen",contentRaw:'[{"type":"htmlEditorComponent","content":"