공조용 알루미늄 납작관 내의 R-410A 대류 비등

Abstract

Abstract Flat tube heat exchangers can improve the thermal performance significantly compared with round tube heatexchangers. For proper design of flat tube heat exchangers, one should know the tubeside heat transfer coefficients.In this study, convective boiling heat transfer coefficients of R-410A were obtained in a flat extruded aluminum tubewith D h =1.41 ㎜ . The test range covered mass flux from 200 to 600kg/m 2 s, heat flux from 5 to 15kW/m 2 and saturationtemperature from 5 ℃ to 15 ℃ . The heat transfer coefficient curve shows a decreasing trend after a certain quality(critical quality). The critical quality decreases as the heat flux increases, and as the mass flux decreases. Theearly dryout at a high heat flux results in a unique 'cross-over' of the heat transfer coefficient curves. The heat transfercoefficient increases as the mass flux increases. At a low quality region, however, the effect of mass flux is not prominent. The heat transfer coefficient increases as the saturation temperature increases. The effect of saturation temperature, however, diminishes as the heat flux decreases. Both the Shah and the Kaew-On et al. correlations reasonably predicted the present data.