• 설비공학논문집
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• 제2권1호
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• pp.27-36
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• 1990

An experimental investigation was made to study the performance characteristics of evaporator having different fin configurations and tube inner grooves. Three different types of fin such as super slitted fin, slitted fin, plain fin, and two types of tube such as inner grooved tube, and bare tube, are tested varying the air velocity, evaporation temperature and superheat of refrigerant. Results show that in the range of air side Reynolds number $3{\times}10^3\;-\;1.5{\times}10^4$ evaporator with super slitted fin and inner grooved tube shows best performance. It is 80% higher in overall heat transfer coefficient and 2.6 times higher in pressure loss compared to that with plain fin inner grooved tube. Friction factor is found to be almost independent of evaporating temperature and degree of superheat, while Colburn j factor varies with evaporating temperature.

• 한국태양에너지학회 논문집
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• 제24권3호
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• pp.39-46
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• 2004

In this paper, thermodynamic design data for heating of double-effect absorption system using LiCl-water for evaporator heating source of sofar energy are investigated for the water-LiCl pair and a comparative study of the water-LiCl pair with the water-LiBr pair is given used for the computer simulation. The computer simulation is based on mass, material and heat balance equations for each part of the system. Coefficients of performance and flow ratios for effects of different operating temperatures are investigated. It is found that the heating COP is higher for the water -LiCl pair than for the water-LiBr pair, and FR is lower for the water-LiCl pair than for the water LiBr pair.

• 동력기계공학회지
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• 제6권4호
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• pp.16-22
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• 2002

This study was conducted to find performance evaluation method for automobile air conditioner. Experimental facilities were constructed to simulate wide range of operating condition for the automobile air conditioner. Compressor speed was controled by variable speed electric motor and the power was measured through torque transducer and tachometer was used to measure compressor speed. Parametric studies were conducted in this study, to figure out effect of environment variables on the performance of the automobile air conditioner. The environmental variables are inlet air temperature, relative humidity and air flow rate for the evaporator and inlet air temperature and air flow rate for the condenser. Compressor speed is also changed. The results of this study shows that air flow rate of the evaporator is more sensitive to the performance of the automobile air conditioner than the other variables. However relative humidity of the inlet air of the evaporator strongly affects capacity rather that COP.

• 설비공학논문집
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• 제16권3호
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• pp.230-240
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• 2004

An experimental investigation was conducted to study two-phase flow distribution in a T-type distributor of slit fin-and-tube heat exchanger using R22. A comparison was made between the predictions by previously proposed tube-by-tube method and experimental data for the heat transfer rate of evaporator. Experiments were carried out under the conditions of saturation temperature of 5$^{\circ}C$ and mass flow rate varying from 0.6 to 1.2kg/min. The inlet air has dry bulb temperature of 27$^{\circ}C$, relative humidity of 50% and air velocity varying from 0.63 to 1.71㎧. Experiment show that air velocity increased by 85.2% is need for T-type distributor with four outlet branches than that of two outlet branches under the superheat of 5$^{\circ}C$, which resulted in air-side pressure drop increase of 130% for T-type distributor with four outlet branches as compared to two outlet branches.

• 한국가시화정보학회지
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• 제17권1호
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• pp.10-18
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• 2019

In this study, the temperature behavior of Pulsating Heat Pipe (PHP) according to the diameter change were studied by limiting the diameter change to only the evaporator. To investigate operation of PHP in various heat input, heat input power was increased from 10 to 120 W. The results show operation can be divided into 3 regimes by temperature behavior. Thermal resistance was increased before start-up and decreased with increasing heat input. At 110 W heat input, thermal conductivity of 2 mm PHP was 8 .times higher compare to thermal conductivity of copper. Further, to investigate details of temperature behavior in higher heat input, FFT analysis was conducted. Based on the results, when the deviation of peak frequency in each section is lowest, the thermal resistance has lowest value.

• 대한설비공학회지:설비저널
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• 제15권4호
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• pp.356-361
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• 1986

An optimum design condition for a basic refrigeration cycle is defined as the condition which minimizes the total cost of heat exchanges (condenser and evaporator) and compressor for the refrigeration effect. Thermodynamic properties of ammonia (R717) are approximated by rational functions in order to obtain the optimum condition for a basic refrigeration cycle. Optimum condition depends on the heat capacity rates (mass flow rate times specific heat) of cooling water and brine used in condenser and evaporator. The difference between the cooling water temperature and condensation temperature at the optimum condition increases as the heat capacity rates and the coat of heat exchangers relative to the cost of compressor increase. Numerical examples of optimum conditions are obtained when the condensation temperature is $30^{\circ}C$ and the evaporator temperature is $-10^{\circ}C$.

• 한국산학기술학회논문지
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• 제22권2호
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• pp.558-564
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• 2021

정수기는 최근 시장규모가 급격한 증가 추세에 있으며, 얼음 정수기의 얼음 생성량과 냉수 성능을 결정하는 핵심 부품인 증발기의 용접기술 향상을 요구하고 있다. 얼음 정수기의 finger type 증발기는 얼음을 탈빙 시키는 방법으로 순간 히터 방식과 고온 가스 방식으로 크게 구분되며 일부 대기업을 중심으로 생산 및 개발이 진행되고 있다. 두 방법은 장·단점을 가지고 있으며 고온 가스 방식 증발기는 특히 생산과정에서 고열의 산소 용접으로 인해 동파이프 내부에 pin hole 현상과 고압관 용접시 막힘 문제가 간헐적으로 발생하고 있다. 이는 정수기 사용시 얼음과 차가운 물의 생기지 않는 문제점을 가져오며 현장에서 수리가 불가능하다. 이러한 문제점을 해결하기 위해 본 논문에서는 고온 가스 증발기의 용접 불량을 개선하기 위해 cap jig를 적용하였다. 또한 산소용접 불꽃 크기를 조절하여 cap jig에 열원이 잘 공급될 수 있도록 하고 파압 시험과 테스트와 열충격 시험을 통해 유효성을 확인하였다.

• 대한기계학회논문집
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• 제5권2호
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• pp.151-157
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• 1981

The concept of available evergy has been adopted in terms of effectiveness for and evaporator of vapor power cycle. This kind of practice is emphasezed in a case of heat and power cogeneration in order to find optimum condition for the energy utilzation of the exhaust gas. It has beed shown that the optimum condition can be given in terms of the saturation pressure or the saturation temperature of the working fluid. Similar method has been applide to show that the effectiveness is increased asymptotically with the number of evaporator stanges.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2005년도 창립60주년 기념 추계 학술대회
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• pp.41.1-41.1
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• 2005

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.309-313
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• 2000

An experimental study was conducted to analyze the characteristics of the showcase refrigeration system during frosting and defrosting process. Test showcase was constructed with a cooling capacity of 3RT including 3 evaporators. The dynamic characteristics of the system under frosting and defrosting conditions were investigated. Refrigerant temperature and pressure of the system, dry bulb and wet bulb temperature of air passing through the evaporator, air flow rate and compressor power were measured.