응축수 맺힘조건에서 슬릿형상을 갖는 핀-튜브 열교환기의 공기측 압력강하 및 열전달 특성에 관한 연구
Year of publication 2005
Title of paper 응축수 맺힘조건에서 슬릿형상을 갖는 핀-튜브 열교환기의 공기측 압력강하 및 열전달 특성에 관한 연구
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Abstract Since an evaporator of a household air-conditioner works below dew point temperature, water vapor in moist air condenses onto coil surface. The characteristics of the evaporator under wet conditions is very complicated due to the mass transfer and configuration of condensate film. Many experimental studies were published, but their results were much different from each other. In order to develop the general correlation of heat transfer coefficient in an evaporator at wet surface conditions, further studies are required. An experimental study was performed in compact finned tube heat exchangers under wetting conditions. Eight finned tube heat exchangers having slit fin were tested. The number of tube rows was 1, 2 and 3, and the tube diameters were 5.30, 7.35 and 9.95 mm. The air-side heat transfer coefficients were calculated by the log-mean-enthalpy-difference method and the pressure drop of the air passing through the heat exchangers were estimated with a differential pressure transducer, which were presented in terms of the j-factor and friction factor, respectively. The effects of tube diameter, the number of tube rows and inlet humidity on air-side heat transfer coefficient and pressure drop were investigated. As a result, the effects of wetting surface on the j-factor became more significant with increasing of the Reynolds number and with decreasing of the number of tube rows. The friction factor was less sensitive to the air-side relative humidity.
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