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배석정,이정희,최영기 대한설비공학회 2003 설비공학 논문집 Vol.15 No.11
A numerical program has been developed for the simulation of automotive engine cooling system. The program determines the mass flow rate of engine coolant circulating the engine cooling system and radiator cooling air when the engine speed is adopted by appropriate empirical correlation. The program used the method of thermal balance at individual element through the model for radiator component in radiator analysis. This study has developed the program that predicts the coolant mass flow rate, inlet and outlet temperatures of each component in the engine cooling system (engine, transmission, radiator and oil cooler) in its state of thermal equilibrium. This study also combined the individual programs and united into the total performance analysis program of the engine cooling system operating at a constant vehicle speed. An air conditioner system is also included in this engine cooling system so that the condenser of the air conditioner faces the radiator. The effect of air conditioner to the cooling performance, e.g., radiator inlet temperature, of the radiator and engine system was examined. This study could make standards of design of radiator capacity using heat rejection with respect to the mass flow rate of cooling air. This study is intended to predict the performance of each component at design step or to simulate the system when specification of the component is modified, and to analyze the performance of the total vehicle engine cooling system.
엔진 냉각수 폐열 회수를 위한 ORC 시스템 및 폐열 회수 열교환기 설계
배석정(Sukjung Bae),허형석(Hyungseok Heo),황재순(Jaesoon Hwang),박정상(Jeongsang Park),이홍열(Hongyeol Lee) 한국자동차공학회 2011 한국자동차공학회 부문종합 학술대회 Vol.2011 No.5
A 2-loop waste heat recovery system with Rankine steam cycles for the improvement of fuel efficiency of a gasoline vehicle has been established. A high temperature loop system is used to recover waste heat from exhaust gas, and a low temperature loop system is used for heat recovery from the relatively cold engine coolant. This paper has dealt with a layout of an low temperature loop system, a review of the working fluids, and the design of the cycle. R1234yf has been chosen as the working fluid. The design point and the target heat recovery of the LT boiler, a core heat exchanger for the organic Rankine cycle, has been presented and analytically investigated. Considering the characteristics of the cycle, the basic concept of the heat exchanger has been determined to be a shell-and-tube type counter flow heat exchanger. The performance characteristics for various design parameters were investigated.
배기 폐열 회수 시스템의 고온 열교환기 설계 및 성능 평가
배석정(Sukjung Bae),허형석(Hyungseok Heo),이동혁(Donghyuk Lee),강태구(Taegu Kang),김태진(Taejin Kim) 한국자동차공학회 2012 한국자동차공학회 부문종합 학술대회 Vol.2012 No.5
A dual loop waste heat recovery system with Rankine steam cycles for the improvement of fuel efficiency has been investigated. This paper deals with performance analysis and evaluation of heat exchangers on the exhaust gas side for the design of them. The HT boiler and the HT superheater are placed along the exhaust line. In the HT boiler, the working fluid compressed by the pump becomes saturated by the recovery of heat of exhaust gas. On the other hand, in the HT superheater, the working fluid becomes superheated as it recovers heat of upstream exhaust gas coming out from the exhaust manifold. An analysis program was developed to design the HT superheater and the HT boiler. For the performance evaluation of each component, inlet temperature was set 5℃ of sub-cool and 5℃ of super-heat at the high pressure on the condition of designed evaporating pressure. The predictive value and the result of thermal performance evaluation was consistent on the average value within 5%. In addition, the another experiments were performed with the HT superheater and the HT boiler connected in series. The inlet temperature was set 5℃ of sub-cool at the low pressure of the system and outlet temperature was set the degree of 300℃.Using the result of this paper, the design criteria of a high temperature heat exchanger will be established for the exhaust heat recovery system.
xEV 발열부품 열관리 시스템의 냉각수 제어를 위한 유동 특성 평가
배석정(Sukjung Bae),허형석(Hyungseok Heo),이현석(Hyunseok Lee) 한국자동차공학회 2022 한국자동차공학회 학술대회 및 전시회 Vol.2022 No.11
The central thermal management system of xEV is an indirect system that a secondary fluid is used as the heat transfer media other than a refrigerant used in a direct system in order to enhance mileage of xEV and simplify the layout. The system controls the coolant for thermal management of heat emitting parts at different temperature levels by using heat sources and refrigerant vaporization heat. The thermal management system of heat emitting parts has various coolant control modes such as cabin heating, cabin cooling, battery cooling, and PE cooling modes, etc, in which the system resistance varies with arrangement of the components in the coolant circuit. In this study, flow characteristic assessment has been performed to acquire the data for coolant with respect to the control modes. The results can be used to control the coolant flow rate according to the EWP rotating speed depending upon the mode with respect to the situation.
특성 방법을 이용한 Fuel Rail 압력맥동 특성 해석 프로그램 개발
배석정(Sukjung Bae),허형석(Hyungseok Heo),이헌균(Heonkyun Lee),송경석(Kyungsuk Song),박시우(Seewoo Park),김보겸(Bokyoum Kim) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
In the return less fuel rail system of MPI engine, pulsation damper is commonly mounted for the purpose of diminution of pressure pulsations and jarring noise. But, pulsation damper is too expensive for all the advantage. Therefore, the studies are on the increase to develop fuel rail to diminish pulsations with integrated damping effect. This paper deals with numerical approach using method of characteristics to design fuel rail to reduce pulsations with self-damping effect. Primarily, the pressure pulsation characteristics is investigated with aspect ratio of cross section, wall thickness, and materials of fuel rail. Secondarily, sweep test simulation of fuel rail for in-line engine is performed as engine speed increases to find out certain engine speed where pressure pulsation peak is observed. A high aspect ratio or thin wall is found to absorb the pressure pulsations effectively. The fuel rail made of aluminum is effective for reduction of pressure pulsation than that of low-carbon steel. Pressure pulsation peak is observed at the vicinity of certain engine speed where single-injector oil hammer simulation predicts that resonance would occur.
배석정(Sukjung Bae),허형석(Hyungseok Heo),이동혁(Donghyuk Lee),이헌균(Heonkyun Lee),강태구(Taegu Kang),김태진(Taejin Kim) 한국자동차공학회 2011 한국자동차공학회 부문종합 학술대회 Vol.2011 No.5
A waste heat recovery system with Rankine steam cycles for improving the fuel efficiency of gasoline automobiles has been investigated. The system recovers waste heat from engine exhaust gas. The design point and the target heat recovery of an evaporator, which is a core part of the system, have been presented. A prototype evaporator was evaluated by an experiment. The inlet temperature condition of the boiler working fluid was set to a degree of subcool of 5 ℃. The exit condition was the degree of superheat, which was set at 5℃. Heat recovery and pressure drops of fluids were evaluated for varying flow rates and inlet temperatures of the exhaust gas. A prototype boiler was also evaluated in order to set an effective design for the layout of heat recovery system.
배석정(Sukjung Bae),김진수(Jinsu Kim),허형석(Hyungseok Heo),서재수(Jaeso Seo),김종근(Jongkeun Kim) 한국자동차공학회 2015 한국자동차공학회 부문종합 학술대회 Vol.2015 No.5
The heat transfer of the evaporator of a vehicle air-conditioning system is directly related to the system cooling performance, which serves to export the cooled air into cabin. Recent technology of heat exchangers for vehicle air conditioning system has been developed in aspects such as densification of the heat transferring fins, compact design of slits and louvers, and high air flow design, which yields the necessity of the technology to keep the air flow resistance in control. In this study, the structure of louvered fin of the evaporator has been modified from the conventional one to form wavy geometries to improve the drainage. An air flow analysis has been conducted to analyze the pressure drop or the distribution of the flow.