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Enhancement of the turbocharger compressor performance by designing a new housing structure
Zhou Tianjun(주천준),Geun Sik Lee(이근식) 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.12
In this study, we examined two turbocharger compressor housing structures to improve the turbocharger compressor pressure ratio and efficiency. A certain type of recirculating casing treatment(RCT) can improve the compressor performance near the surge line. And a Hybrid RCT adopting both RCT in the inlet duct and a passage from a volute section to the RCT side can improve the compressor performance at a certain engine operating range. There are 8 different hole position models for Hybrid RCT compressor. Using the CFX software, we obtained the simulation results of all compressor models. At 140,000RPM, the Hybrid-RCT with the different connecting hole position has different performance for pressure ratio and efficiency. Among 8 Hybrid-RCT models, the Hybrid 270D model showed the best performance in the operating range from 0.077kg/s to 0.10kg/s.
고성능 상용튜브를 사용한 태양열 가열 해양온도차발전용 열교환기 설계 최적화
주천준(Zhou Tianjun),웬반합(Nguyen Van Hap),이근식(Geun Sik Lee) 대한기계학회 2016 大韓機械學會論文集B Vol.40 No.9
태양열 가열을 도입한 해양온도차발전용 열교환기(증발기와 응축기)설계 최적화가 수행되었다. 출력은 100kW이고 작동유체는 R134a이며 고성능 상용튜브를 사용하였다. 열전달면적과 압력강하는 관수의 증가와 관통로수의 감소에 따라 서로 상반되는 경향이 존재하므로 이를 해결하기 위하여, 설비투자비에 관련되는 열전달면적과 압력강하에 관련되는 운전비용 최소화를 고려한 두 목적함수를 갖는 유전자 알고리즘(GA)을 이용하여 다목적설계최적화를 수행하였다. 설계최적화 결과, 구현 가능한 최적의 열전달면적 및 압력강하의 조합들이 적정한 관수 및 관통로 수에 대하여 존재하였다. 도출된 증발기와 응축기의 Pareto 선들은 설계자들에게 재정적인 면을 고려하여 선택할 수 있도록 넓은 범위의 최적해를 제공하였다. 또한, 총열전달면적 중 응축기의 열전달면적이 증발기 쪽보다 크게 나타났다. In this study, the optimal design of heat exchangers, including the evaporator and condenser of a solarheating ocean thermal energy conversion (SH-OTEC), is investigated. The power output of the SH-OTEC is assumed to be 100 kW, and the SH-OTEC uses the working fluid of R134a and high-performance commercial tubes. The surface heat transfer area and the pressure drop were strongly dependent on the number of tubes, as well as the number of tube passes. To solve the reciprocal tendency between the heat transfer area and pressure drop with respect to the number of tubes, as well as the number of tube passes, a genetic algorithm (GA) with two objective functions of the heat transfer area (the capital cost) and operating cost (pressure drop) was used. Optimal results delineated the feasible regions of heat transfer area and operating cost with respect to the pertinent number of tubes and tube passes. Pareto fronts of the evaporator and condenser obtained from multi-objective GA provides designers or investors with a wide range of optimal solutions so that they can select projects suitable for their financial resources. In addition, the surface heat transfer area of the condenser took up a much higher percentage of the total heat transfer area of the SH-OTEC than that of the evaporator.