경사진 헬리컬 코일 열교환기의 열전달 특성에 관한 연구
Heat Transfer Characteristics of Inclined Helical Coil Type Heat Exchanger
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Abstract
The heat transfer coefficient and pressure drop during gas cooling process of CO2 (R-744) in inclined helical coil copper tubes were investigated experimentally. The main components of the refrigerant loop are a receiver, a variable-speed pump, a mass flow meter, a pre-heater and a inclined helical coil type gas cooler (test section). The test section consists of a smooth copper tube of 2.45 mm inner diameter. The refrigerant mass fluxes were varied from 200 to 600 [kg/m2s] and the inlet pressures of gas cooler were 7.5 to 10.0 [MPa]. The heat transfer coefficients of CO2 in the inclined helical coil tubes increases with the increase of mass flux and gas cooling pressure of CO2. The pressure drop of CO2 in the gas cooler shows a relatively good agreement with those predicted by Ito’s correlation developed for single-phase in a helical coil tube. The local heat transfer coefficient of CO2 agrees well with the correlation by Pitla et al. However, at the region near pseudo-critical temperature, the experiments indicate higher values than the Pitla et al. correlation. Therefore, various experiments in the inclined helical coil tubes have to be conducted and it is necessary to develop the reliable and accurate prediction determining the heat transfer and pressure drop of CO2 in the inclined helical coil tubes.
참고문헌 (13)
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