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좁은 공간내의 밀폐형 장치 냉각시스템에 대한 열평형 평가
김성광,안석환,남기우 한국해양공학회 2007 韓國海洋工學會誌 Vol.21 No.3
In this study, the heat balance test of an engine was conducted, and the heat released to coolant is measured and corrected using a power adjustment factor for high fuel temperature to simulate heat rejection of the engine. An engine-converter matching simulation program which can compute the engine speed, transmission output speed, transmission input and output power is developed from the vehicle, transmission and engine performance curve. With this information and the engine heat rejection characteristics, the engine and transmission heat rejection rates can be determined at given condition. In analyzing the air mass flow, a sub program computing the air mass flow rate from the equation of the pressure balance between cooling fan static pressure rise and pressure losses of cooling components is developed.1. 서 론 최근 고출력 디젤엔진을 장착한 밀폐형차량은 냉각 요구조건은 점점 가혹해지고 있는 반면, 설치공간은 작아지고 복잡해 지고 있어 제한된 공간에서 적절한 냉각용량을 확보하는 것은 어려운 일이며 이에 따라 좁은 공간내에서 차량에 알맞은 냉각용량을 설계는 매우 중요한 인자가 된다(Corbel, 1987). 따라서 엔진 및 차량 제조업체에서는 차량의 사용조건을 고려하여(-32℃~+50℃) 과열 및 과냉 방지와 엔진의 열효율을 극대화할 수 있는 적절한 냉각용량을 결정하여 가능한 한 실제 차량에 적용한 조건에 유사한 상태로 차량 냉각시험을 실시하여 적합성을 검토하고 최종적으로 차량시험을 실시하여 시스템을 증명할 필요가 있다. 특히 밀폐형차량의 경우 차량 냉각을 시킬수 있는 열교환기 및 휀의 설계가 무엇보다도 중요하다. 압축착화방식을 사용하는 디젤엔진의 냉각 손실은 대략 20~30(%) 정도이며 엔진의 내구성 및 열효율을 높이기 위한 방안으로 고온의 연소가스와 접촉하는 연소실을 일정한 온도범위 이내로 유지시켜 주어야 한다(Xu et al., 1984; Chiang et al., 1982; 1982; Nutt and Poehlma, 1982). 차량냉각시스템에 대한 요구성능의 증가에 따라 방열기의
Ralu-Pack 250YC 를 충전한 충전탑에서 암모니아가스 제거에 관한 연구
김석택 한국환경과학회 2000 한국환경과학회지 Vol.9 No.5
In this study a packed tower was selected for the treatment apparatus of NH_3 gas produced in industry. Formerly, latticework packing has been used in preventive facility of treatment of NH_3 gas. However, recently metallic Ralu-Pack 250YC, structured packing, is usually being used in petrochemical production plant. This study is for the application the packing to the NH_3 gas treatment in wet scrubbing process. In Air/water system, hydraulic pressure drop dependent of specific liquid load and gas capacity factor was continuous and parallel from graph. The tower height can be determined by the number of transfer unit and the height of transfer unit influenced on liquid distribution.
열교환기 형식에 따른 열교환기의 에너지 및 엔트랜시 성능 특성 해석
김경훈,정영관,한철호 한국수소및신에너지학회 2020 한국수소 및 신에너지학회논문집 Vol.31 No.1
In this work energy and entransy characteristics of heat exchangers are analyzed for 12 different flow arrangements of heat exchangers. The dimensionless parameters are number of entransy dissipation (Ng), number of entransy dissipation-based thermal resistance (Nr), and entransy dissipation-based effectiveness of heat-exchanger (εg). The dimensionless parameters are expressed analytically in terms of the effectiveness of heat exchanger (ε), heat capacity ratio (c), and number of transfer unit (N) for optimal performance of heat exchangers. Results showed that the dimensionless parameters based on the entransy dissipation can be useful concepts for optimal design of heat exchangers.
판형 열교환기 Full-scale 해석을 위한 1차원 유동 네트워크 모델 및 ε-NTU 모델의 수치적 연구
김민성(Minsung Kim),민준기(June Kee Min),하만영(Man Yeong Ha) 한국전산유체공학회 2014 한국전산유체공학회지 Vol.19 No.1
Since a typical plate heat exchanger is made up of a huge number of unitary cells, it may be impossible to predict the aero-thermal performance of the full scale heat exchanger through three-dimensional numerical simulation due to the enormous amount of computing resources and time required. In the present study, a simple flow-network model using the friction factor correlation and a thermal-network model based on the effectiveness-number of transfer units (ε-NTU) method has been developed. The complicated flow pattern inside the cross-corrugated heat exchanger has been modeled into flow and thermal networks. Using this model, the heat transfer between neighboring streams can be considered, and the pressure drop and the heat transfer rate of full-scale heat exchanger matrix are calculated. In the calculation, the aero-thermal performance of each unitary cell of the heat exchanger matrix was evaluated using correlations of the Fanning friction factor f and the Nusselt number Nu, which were calculated by unitary-cell CFD model.
차량의 파워 트레인과 운전 조건이 차량의 냉각 성능에 미치는 영향
박종남,김재호,차경옥 明知大學校 産業技術硏究所 2003 産業技術硏究所論文集 Vol.22 No.-
Abstract - With the ever increasing demanded on automatic transmission, improve performance, add air conditioning, meet noise and pollution legislation the need to evaluate and improve cooling system performance at the design stage is becoming increasingly important. ATB is the abbreviation for Ait-to-Boil. This is the extrapolated ambient temperature at which the coolant would boil. ATB is the measure of cooling system capability. Coolant temperature control insures durability and long engine life in vehicle users application. A numerical simulation is conducted to compare the various experimental results by the "e-NTU" method. The purpose of this paper is to suggest the matching technique of vehicle cooling system including automatic transmission by means of various experimental results and comparing with simulation results.