고온 초전도체 팬케이크 코일의 퀜치 해석

박차식,안태길,박경우,김도형,차귀수,서정식,Park, C.S.,Ahn, T.K.,Park, K.W.,Kim, D.H.,Cha, G.S.,Seo, J.S. 한국초전도저온학회 2009 한국초전도저온공학회논문지 Vol.11 No.3

The thermal characteristics of quench propagation is a crucial problem for the stability of the superconductor. The objective of this study is to simulate the quench propagation with the variation of disturbance energy in Bi-2223/Ag HTS pancake coil. In this analysis, the temperature-time trace of a point away from heater was calculated under conditions of different quench energy. The critical disturbance energy between quench propagation and quench recovering was calculated, In addition, the minimum quench energy with different transport currents was obtained through the present simulation. These results are significant to the application of HTS.

열병합시스템 경제성 평가 프로그램의 개발 및 적용에 관한 연구

박차식,김용찬,Park, Chasik,Kim, Yongchan 대한기계학회 1998 大韓機械學會論文集B Vol.22 No.11

The object of this study was to develop an economic assessment program for the optimal design of the cogeneration systems composed of combining engine, generator, waste heat recovery exchanger, absorption chiller, and boiler, etc. The energy demand categorized by electric power, heating, cooling and water supply was determined by statistical data of the existing cogeneration systems. An economic assessment was performed by comparing the total cost of cogeneration system with that of non-cogeneration system. The total cost was evaluated by adding initial investment to operational cost considering efficiency of equipment, cost of equipment, fuel and electricity. To confirm the validity of the developed program, a hotel building with an area of $127,960m^2$ was selected, and the simulated results were compared with the measured data. The difference between the simulated and the measured values for the selected hotel building was approximately 12% for annual electric consumption.

증기압축식 공조시스템의 대체기술 분석

박차식(Chasik Park),박상민(Sangmin Park),이태윤(Taeyoon Lee),강철중(Chuljung Kang),박상우(Sangwoo Park) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11

증기압축식 공조시스템의 대체기술 분석

박차식(Chasik Park),박상민(Sangmin Park),이태윤(Taeyoon Lee),강철중(Chuljung Kang),박상우(Sangwoo Park) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11

지역난방용 2단 압축 히트펌프 시스템 성능평가

박차식(Chasik Park),차동안(Dong An Cha),권오경(Oh Kyung Kwon) 대한설비공학회 2012 설비공학 논문집 Vol.24 No.7

The objective of this study is to investigate the performance of a two-stage compression heat pump system for district heating. The experimental setup of heat pump consists of compressor, condenser, evaporator, expansion device, intercooler, flash tank, oil separator and accumulator. The experimental evaluations on the two-stage compression cycle were carried out under various operating conditions which were heat source temperature, the degree of compressor inlet superheat, and intermediate pressure. The temperature ranges of unutilized energy as the heat source were used in the test conditions. As the heat source temperature increased from 10℃ to 30℃, the COP and heating capacity of the heat pump system increased by 22.6% and 45.8%, respectively. The performance of the two-stage heat pump system increased by 5.2% with the variation of the intermediate pressure in the same heat source temperature conditions.

하천수 열원 2단압축 열펌프의 최적 중간압에 관한 실험적 연구

박차식(Chasik Park),정태훈(Taehun Jung),주영주(Youngju Joo),김용찬(Yongchan Kim) 대한설비공학회 2009 설비공학 논문집 Vol.21 No.6

The objective of this study is to predict optimal intermediate pressure of a 2-stage compression heat pump system using river water. To determine the maximum performance of the 2-stage compression heat pump system, the experimental evaluations on the 2-stage compression cycle were carried out under various operating conditions. Electronic expansion valves were applied to control intermediate pressure and superheat. Based on the experimental data, an empirical correlation for predicting optimal intermediate pressure which considering cycle operating parameters was developed. The present correlation was verified by comparing the predicted data with the measured data. The predictions showed a good agreement with the measured data within a relative deviation of ±4% at various operating conditions.

내부열교환기와 TXV를 적용한 자동차용 공조시스템의 성능에 관한 수치적 연구

박차식(Cha-Sik Park) 한국산학기술학회 2021 한국산학기술학회논문지 Vol.22 No.1

최근에 지구온난화 문제로 인하여 자동차 공조시스템은 GWP 지수가 높은 R134a 냉매를 대체할 수 있는 대체 냉매를 적용하고 있다. 본 연구에서는 R1234yf 냉매를 사용하여 내부열교환기와 가면용량형 팽창밸브인 TXV를 적용한 자동차 공조시스템의 성능특성을 해석하였다. 상용 소프트웨어인 Amesim을 이용하여 주요 부품인 압축기, 응축기, 팽창장치, 증발기와 내부열교환기를 모델링을 하여 외기온도와 응축기 휜 피치 변화에 따른 냉동사이클 시뮬레이션을 수행하였다. 외기온도가 30℃에서 40℃로 증가함에 따라 시스템의 냉방용량은 3.1% 감소하고, 압축기 소비동력은 17.1%증가하였다. 또한, 응축기의 휜 피치를 0.8 mm에서 1.4 mm로 증가시키면서, 사이클 성능특성을 해석하였다. 휜 피치가 1.0 mm 클 경우에 응축기의 방열량은 감소하였고, COP는 5.9% 까지 감소하였다. 응축기 휜 피치가 1.0 mm 보다 작은 0.8 mm에서는 시스템 성능에 큰 변화가 없어 휜 피치 1.0 mm에서 최적의 성능을 나타내는 것으로 분석되었다. Recently, automobile air conditioning systems have applied an alternative refrigerant that can replace the high GWP refrigerant R134a due to the global warming problem. This study simulated the performance of an automobile climate control system with an internal heat exchanger and TXV. Refrigerant R1234yf was applied as the working fluid. Amesim, a commercial software program, was used to model the main components of the compressor, condenser, TXV, evaporator, and internal heat exchanger. As the outside temperature increased from 30℃ to 40℃, the cooling capacity of the system decreased by 3.1%, and the power consumption of the compressor increased by 17.1%. In addition, The performance characteristics of the refrigeration cycle were simulated by increasing the fin pitch of the condenser from 0.8 mm to 1.4 mm. When the fin pitch was larger than 1.0 mm, the condenser capacity decreased, and the system COP was lowered by 5.9%. When the fin pitch of the condenser was 0.8 mm, which was smaller than 1.0 mm, there was no significant change in the system performance. Hence, the optimal performance was observed at a fin pitch of 1.0 mm.

비증기압축식 냉동사이클 특성에 관한 고찰

박차식(Chasik Park) 호서대학교 공업기술연구소 2022 공업기술연구 논문집 Vol.41 No.2

공조시스템에 적용된 기술의 대부분은 증기압축식 냉동사이클 방법을 사용하여왔다. 증기압축식 시스템은 빌딩공조, 자동차공조, 산업용 냉동기 등에 널리 사용되어진다. 증기압축식 냉동사이클은 작동유체로 냉매를 사용하여 압축, 응축, 팽창, 그리고 증발 과정을 통하여 저온에서 고온으로 열을 이송한다. 그러나, 증기압축식 시스템에 사용된 냉매가 설치나 유지보수를 하는 동안에 대기 중으로 누기가 발생하게 되면 지구온난화의 원인이 된다. 최근에는증기압축식 공조시스템을 대체할 수 있는 다양한 기술이 연구되고 있는데, 본 연구에서는 펄스튜브 냉동기, 보텍스튜브 냉동기, 베르누이 히트펌프, 전기열량 냉동기, 자기열량 냉동기, 열전 냉동기의 6가지 대체기술에 대해서 분석하였다. Most of the technologies applied to the HAVC system have been used the vapor compression refrigeration cycle method. Vapor compression HVAC system can be developed in various capacities and is widely used in building air conditioning, automobile air conditioning, and industrial refrigerator. A vapor compression refrigeration cycle transfers heat from a low temperature to a high temperature through compression, condensation, expansion, and evaporation processes with a refrigerant as a working fluid. However, the refrigerant used in the vapor compression system leaks into the atmosphere during installation and maintenance, causing global warming. Therefore, various technologies that can replace the vapor compression air conditioning system has been studied. In this study, six alternative technologies were analyzed : pulse tube cooling, vortex tube cooling, bernoulli heat pump, electrocaloric cooling, and thermoelectric cooling.

건물의 연면적에 따른 열병합발전 시스템의 경제성 평가

박차식 ( C . S . Park ),김용찬 ( Y . C . Kim ) 고려대학교 공학기술연구소 1998 공학논문집 Vol.36 No.1

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냉매 R1234yf/R1234ze/R152a에 대한 이젝터 적용 냉동사이클의 성능 향상에 관한 연구

박차식(Cha Sik Park) 호서대학교 공업기술연구소 2015 공업기술연구 논문집 Vol.34 No.1

본 연구는 이젝터를 팽창장치로 적용하여 대체냉매에 대한 냉동사이클의 성능향상을 해석적으로 분석하였다. 이젝터 내부의 유동을 연속방정식, 에너지방정식. 그리고 운동량방정식을 이용한 이론식을 모델링하여 해석을 실시하였 다. 해석결과를 통하여 이젝터 적용 냉동사이클의 성능향상은 냉매 R1234yf가 가장 높게 나타났고, R152a가 가장 낮게 나타났다. 또한 증발온도와 응축온도의 차가 증가하는 가혹한 운전 조건일수록 이젝터 냉방사이클의 성능 향상효과가 크게 나타났다. 이젝터 디퓨져의 성능 변화에 대한 영향은 R1234yf 냉매가 가장 크게 나타났다. This paper presents a numerical study on the performance of refrigeration cycle equipped with an eiector using alternative remgerants. The simulation is carried out using the model based on the conservation of mass, energy and momentum in the ejector. Based on the results of simulation, the COP improvements of R1234yf system is highest, Pereas that of R152a system is lowest when the ejector refrigeration cycle is applied. The ejector refrigeration system represents the more irrqjroved effects with the increase of the temperature difference between condensing and evaporating. In addition, the efticiency of the ejector diffuse has an greatest effect on the performance of R1234yf system.