Korean Journal of Air-Conditioning and Refrigeration Engineering (설비공학논문집)

The Society of Air-Conditioning and Refrigerating Engineers of Korea (대한설비공학회)
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Study on Heat Transfer and Pressure Drop Characteristics of Internal Heat Exchanger for $CO_2$ Heat Pump under Cooling Condition

$CO_2$ 열펌프용 내부 열교환기의 냉방조건에서 열전달 및 압력 강하 특성에 대한 연구

  • Published : 2008.08.10
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Abstract

In order to study the heat transfer and pressure drop of an internal heat exchanger for $CO_2$ heat pump under cooling condition, the experiment and numerical analysis were performed. Four kinds of internal heat exchangers with a coaxial tube type and a micro-channel tube type were used. The experimental apparatus consisted of a test section, a power supply, a heater, a chiller, a mass flow meter, a pump and a measurement system. The section-by-section method and Hardy-Cross method were used for the numerical analysis. The effects of the internal heat exchanger refrigerant flow rate, the length of the internal heat exchanger, the operating condition of the gas-cooler, the evaporator and the type of the internal heat exchangers were investigated. With increasing of the flow rate, the heat transfer rate increased about 25%. The heat transfer rate of the micro-channel tube type was higher about 100% than that of the coaxial tube type. With increasing of the length of the internal heat exchanger, the heat transfer rate increased about $20{\sim}50%$. The pressure drop of the low-side tube was larger compared with that of the high-side tube.

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References

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