CAJ | 학술논문

在系统压力p=0.41~0.63 MPa,过冷度ΔTsub=6~12℃,热流密度 q=0.11~10.90 kW?m?2,质量流量 G=147~249 kg? m?2?s?1的条件下,对卧式螺旋管内R134a过冷流动沸腾的换热特性进行了实验研究.分析过冷沸腾条件下螺旋管不同截面上的壁温分布表明:截面周向壁温呈现不均匀分布;螺旋管的截面位置对部分过冷沸腾向充分发展过冷沸腾的转变产生了很大影响.分析了各实验参数对充分发展过冷沸腾换热系数的影响趋势:随着热流密度、系统压力的增大换热系数不断增大;但是,当入口过冷度增大时换热系数却在减小;质量流量对换热系数的影响并不明显.对实验数据进行回归分析,发展了适用于卧式螺旋管内充分发展过冷沸腾换热系数的关联式.
재계통압력p=0.41~0.63 MPa,과랭도ΔTsub=6~12℃,열류밀도 q=0.11~10.90 kW?m?2,질량류량 G=147~249 kg? m?2?s?1적조건하,대와식라선관내R134a과랭류동비등적환열특성진행료실험연구.분석과랭비등조건하라선관불동절면상적벽온분포표명:절면주향벽온정현불균균분포;라선관적절면위치대부분과랭비등향충분발전과랭비등적전변산생료흔대영향.분석료각실험삼수대충분발전과랭비등환열계수적영향추세:수착열류밀도、계통압력적증대환열계수불단증대;단시,당입구과랭도증대시환열계수각재감소;질량류량대환열계수적영향병불명현.대실험수거진행회귀분석,발전료괄용우와식라선관내충분발전과랭비등환열계수적관련식.
The subcooled boiling heat transfer of R134a in a helical tube was experimentally investigated. The experiments were carried out at pressure ranging from 0.41 to 0.63MPa, subcooled from 6 to12℃, heat flux from 0.11 to 10.9 kW?m?2and mass flux from 147 to 249kg?m?2?s?1. The wall temperature distribution of a horizontal helical coil was analyzed on the conditions of subcooled boiling. The experimental results indicate that the wall temperature distributions of the cross sections are non-uniform. The location of the cross section was found to has a significant impact on the transition from partial to fully developed subcooled flow boiling. The effects of the boiling heat flux, refrigerant mass flux, system pressure and inlet subcooling of R-134a on the coefficient of subcooled boiling heat transfer were explored in detail. The R134a subcooled flow boiling heat transfer coefficient increases with an increase in heat flux and system pressure. However, raising the inlet subcooling can cause a reduction on boiling heat transfer coefficient. Besides, the mass flux exhibits rather slight effects on heat transfer coefficient. The correlation of subcooled boiling heat transfer coefficient in horizontal helical coil was developed on the basis of regression analysis of experimental data.