An Experimental Study on Evaporative Heat Transfer Characteristics in a Small Diameter Tube

Title & Authors
An Experimental Study on Evaporative Heat Transfer Characteristics in a Small Diameter Tube
Hwang, Yun-Uk; Kim, Min-Su;

Abstract
Experiments have been performed to investigate evaporative heat transfer characteristics of R-134a flowing in a small diameter tube. Test section was made of stainless steel tube with an inner diameter of 2.2mm and was uniformly heated by electric current which was applied to the tube wall. The local saturation temperature of refrigerant flowing in a tube is calculated from the measured local saturation pressure by using an equation of state. Inner wall temperature was calculated from measured outer wall temperature, accounting for heat generation in the tube and one dimensional heat conduction through the tube wall. Mass quality of refrigerant flowing in a tube was calculated by considering energy balance in the pre-heater and the test section. Heat flux was varied from 19 to 64kW/$\small{m^2}$, and mass flux was chanted from 380 to 570kg/$\small{m^2}$s for each heat flux condition. From this study, heat transfer in a small diameter tube is affected by heat flux as well as mass flux for a wide range of mass quality. Heat transfer coefficient in a small diameter tube is much greater than that in medium sized tubes. Test results in this study are compared with Gungor and Winterton correlation, which gives an absolute average deviation of 27%.
Keywords
Evaporative Heat Transfer;Small Diameter Tube;R-134a;Compact Heat Exchanger;
Language
Korean
Cited by
1.
수평미세관의 직경이 R-22 및 R-407C 비등열전달에 미치는 영향,윤국영;최광일;오종택;

대한기계학회논문집B, 2003. vol.27. 2, pp.163-172
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