• 제목/요약/키워드: Evaporation tube arrangement

검색결과 3건 처리시간 0.016초

김치냉장고 내의 유동 및 열전달 특성에 관한 수치해석 (A Numerical Study on the Flow and Heat Transfer Characteristics in a Kimchi Refrigerator)

  • 윤준원
    • 설비공학논문집
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    • 제15권12호
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    • pp.1078-1087
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    • 2003
  • Kimchi refrigerator is a household electric appliance developed with the wholly domestic technology for maturing and keeping kimchi. However, the principle of keeping is not yet revealed obviously. This numerical study has been conducted to investigate the flow and heat transfer characteristics in a kimchi refrigerator. The effects of arrangement variation of a evaporation tube are examined. Also, the heat transfer characteristics through the insulation material are discussed in detail. The flow and temperature field was simulated using the commercial code of CFX-5.3. A natural convection flow is formed through about 5/6 region from the bottom within the keeping space and accordingly, the 90% region of kimchi containers satisfies the temperature requirement with 0$\pm$0.5$^{\circ}C$. The stagnant flow exists in the upper 1/6 region of the keeping space and accordingly, the stratified high temperature distributions appear in the upper region of kimchi containers. The upward shift of the start location of a evaporation tube improves the temperature concentration toward $0^{\circ}C$ but the pitch variation is of no effect. The heat fluxes on the insulation surfaces show two-dimensional distributions with being higher toward the center. Through the variation of insulation thickness, 3.5% saving of insulation material is obtained under the same heat transfer rate.

R410A 냉매를 사용한 열펌프용 열교환기의 형상에 따른 성능특성 연구 (A Study on Performance Characteristics of Heat Exchanger for Heat Pump with R410A Refrigerant)

  • 정규하;박윤철;오상경
    • 설비공학논문집
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    • 제16권4호
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    • pp.340-348
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    • 2004
  • The air and refrigerant side heat transfer performances are key parameters to improve heat transfer efficiency of the heat exchanger including the fan performance. Design of the fins, treatment of the tube inside, tube diameter and tube array effect heat transfer performance of the heat exchanger. The heat exchanger is used as a condenser at cooling mode and used as an evaporator at heating mode in the heat pump system. The heat pump system uses R410A as the refrigerant. The heat exchangers are consisted with 7 mm diameter tubes with slit-type fins. The study was conducted with variation of arrangement of the refrigerant path and air flow rate and refrigerant pressure drop and heat transfer rate were measured with a code tester. The capacity of the 3 path heat exchanger is more efficient than 2 or 4 path heat exchangers in heating or cooling modes.

$CO_{2}$이용 열펌프의 실외열교환기 성능에 관한 실험적 연구 (An Experimental Study on the Performance of Outdoor Heat Exchanger for Heat Pump Using $CO_{2}$)

  • 장영수;이민규;안영산;김영일
    • 설비공학논문집
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    • 제17권2호
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    • pp.101-109
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    • 2005
  • The purpose of this study is to investigate the performance of outdoor heat exchanger for heat pump using carbon dioxide. Two types of fin and tube heat exchangers (2 rows for type A and 3 rows for B) are tested. Both heat exchangers have counter-cross flow and 1-circuit arrangement. Test results such as heat transfer rate, pressure drop characteristics and temperature distribution in the heat exchanger are shown with respect to mass flow rate of refrigerant and frontal air velocity For cooling mode, the minimum temperature difference between air and refrigerant of type B is smaller than that of type A by $1^{circ}C$, but the pressure loss of air side is much higher for type B by $29\%$. It is found that a large temperature gradient of carbon dioxide during gas cooling Process Promotes thermal conduction through tube wall and fins which results in degradation of heat transfer performance. For heating mode operation, type B heat exchanger shows higher heat transfer performance compared to type A. However, because pressure loss of refrigerant side of type B is much greater than that of type A, the refrigerant outlet pressure of type B becomes lower than that of type A.