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Analysis of Real Gas Effects in Natural Gas Turbo-Expanders

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dc.contributor.advisor송성진-
dc.contributor.author최윤정-
dc.date.accessioned2017-10-31T07:32:27Z-
dc.date.available2017-10-31T07:32:27Z-
dc.date.issued2017-08-
dc.identifier.other000000145650-
dc.identifier.urihttps://hdl.handle.net/10371/137333-
dc.description학위논문 (석사)-- 서울대학교 대학원 공과대학 기계항공공학부, 2017. 8. 송성진.-
dc.description.abstractDuring transport and storage of natural gas, natural gas turbo-expanders are used to throttle the high pressure gas and to increase the system efficiency by extracting additional work. This study reports how real gas effect influence prediction of the flow field in the turbo-expander focusing on mass flow rate and efficiency. The tested thermodynamic gas models include the polytropic ideal gas law (PIG), Peng-Robinson equation of state (PR), and Redlich-Kwong equation of state (RK). Simulations have been performed with Ansys CFX 17.0. and methane has been selected as the working fluid. Real gas equation of state is validated by comparing the calculated compressibility factor with that of measured REFPROP. Simulation with the RK EOS has been selected as the reference. PIG model shows a 13% and 20% difference the mass flow rate and efficiency, respectively. PR and RK models show similar results, showing less than 2.1% difference in mass flow rate and efficiency. Predicted density determines mass flow rate. With the blocking effect due to separation bubble, the effective area is the smallest in the PIG law and the mass flow rate is also the smallest. The smaller efficiency arises from larger loss. The losses are analyzed at the nozzle, nozzle-impeller interface, and impeller, respectively by entropy generation. With the large expansion ratio, nozzle wake and separation bubble on the impeller suction surface, PIG law shows 3 times larger loss than that of reference. Mass flow rate and efficiency are important design factors, so real gas effects need to be considered for turbo-expander design and analysis.-
dc.description.tableofcontentsAbstract ···············································································ⅰ
Contents ··············································································ⅲ
List of Figures ·································································ⅳ
List of Tables ···································································ⅵ
Nomenclatures ··································································ⅶ
Chapter 1. Introduction ··································································1
Chapter 2. Numerical Method ················································· 3
2-1. Mesh quality assessment ···························································· 3
2-2. Solver setup ····················································································4
2-3. Equation of state for gases ······················································6
Chapter 3. Results and Discussion ·································· 11
3-1. Mass flow rate ·············································································11
3-2. Efficiency ·······················································································13
Chapter 4. Conclusions ································································39
References ································································································40
Abstract(Korean) ···············································································42
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dc.formatapplication/pdf-
dc.format.extent1156833 bytes-
dc.format.mediumapplication/pdf-
dc.language.isoen-
dc.publisher서울대학교 대학원-
dc.subjectturbo-expander-
dc.subjectequation of state-
dc.subjectnatural gas-
dc.subjectCFD-
dc.subjectreal gas effect-
dc.subjectideal gas-
dc.subjectmethane-
dc.subject.ddc621-
dc.titleAnalysis of Real Gas Effects in Natural Gas Turbo-Expanders-
dc.typeThesis-
dc.description.degreeMaster-
dc.contributor.affiliation공과대학 기계항공공학부-
dc.date.awarded2017-08-
Appears in Collections:
College of Engineering/Engineering Practice School (공과대학/대학원)Dept. of Mechanical Aerospace Engineering (기계항공공학부)Theses (Master's Degree_기계항공공학부)
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