플레이트 핀 열교환기의 열전달 특성에 관한 연구

Abstract

High density and performance of heat exchanger are required along with development of industrial society. Recently, it has been focused on maximized heating surface area per unit volume of the plate-fin heat exchanger. And view of space saving, the design of more cpmpact heat exchanger is relatively important. Also, to meet the demand for saving energy and resources today, manufacturers are trying to enhance efficiency and reduce the size and weight of heat exchanger. Over the past decade, there has been tremendous advancement in the manufacturing technology of high efficiency heat exchanger. This has allowed the use of smaller and high performance heat exchanger. Over the past decades the HCFC (hydro chloro fluoro carbon) refrigerant R22 has been used as the working fluid in many refrigeration. But it will be phased out in a short period of time. Because of its high ozone depletion potential and comparatively high global warming potential. As a result, the search for a replacement for R22 has been intensified in recent years. In this study, the plate-fin heat exchanger is designed two pass flow as counter flow. One side is water, the other side is R22, R134a, 407C. Heat capacity of water is 3.5kW. Heat transfer characteristics were analyzed in heat exchanger with respect to refrigerant mass flowrate. So local and average heat transfer coefficients during evaporation are reported for R22, 407C and R134a in plate-fin heat exchanger. The local and average heat transfer coefficients were measured over a HZ range of 30 to 90, and at saturation temperature of 16℃(evaporation). A comparison of the performance of the different refrigerants reveals that R22 has the highest heat transfer performance followed by R407 which has similar performances, and R134a had the lowest performance of the refrigerants tests.