R134a,R410a and R407e were used to replace R22 as alternative refrigerants for central air-conditioning System.The experiment results show that the location of the tube makes a big difference to the boiling heat transfer coefficients of R22 and its alternative refrigerants on the surface of tube.In the same heat flux range,the boiling heat transfer coefficient of R134a outside tube bundles is 1.26 ～ 1.28 times to that of R22; for R410a, it is 2.62 ～ 3.14 times to that of R22; and for R407c ,it is 0.62 ～0.63 times to that of R22.Heat transfer coefficients of different refrigerants show the similar regularity on the same mechanically processed tube with porous surface.In the analysis of evaporator performance, we find that in the same heat flux range, the total heat transfer coefficients of R407c in evaporator are 0.80 ～ 0.81 times to those of R22 ;for R134a, they are 1.08 ～ 1.10 times to those of R22 ;for R410a,whieh have the best performance in the evaporator,tbey are 1.28 ～ 1.37 times to those of R22.%目前R22的主要替代工质有R134a、R410a、R407c等.利用机械加工表面多孔管可以显著提高R22替代工质满液式蒸发器的沸腾传热系数.本文通过试验研究了R134a、R410a、R407C等工质在机械加工表面多孔管蒸发器中沸腾的传热性能.试验结果表明:相同的热流密度下,R410a的总传热系数是R22的1.28～1.37倍;R407c是R22的0.80～0.81倍.R134a是R22的1.08～1.10倍.机械加工表面多孔管管束效应因制冷剂不同而不同.对R22,下排管沸腾换热系数高于上排管.而对R134a、R410a与R407c,上排管沸腾换热系数最大,中排管和下排管有所不同.
展开▼
