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由于制冷剂 R11 对臭氧层有巨大的破坏作用, 要完成用R123对R11的替代工作, 需要对其替代工质 R123换热性能进行细致研究。对替代工质R123饱和蒸汽在 5 种水平单管外凝结换热的特性进行了实验研究, 冷凝温度分别为38℃、40℃、42℃。实验结果表明, 光管外的凝结换热系数实验值与Nusselt理论值符合较好, 最大偏差不超过±10%。低肋管和锯齿管均能起到明显的强化换热作用,其强化倍率在 8 4~16 0 之间, 且锯齿管的性能优于低肋管。通过实验研究还对 R11 和 R123 在强化管外凝结换热特性进行比较, 证明选用 R123 来替代 R11 凝结换热方面有一定的可行性。
Since refrigerant R11 has a great damaging effect on the ozone layer, to complete the substitution work for R11 with R123, it is necessary to conduct a careful study on the heat exchange performance of R123 instead of working fluid. Experimental studies on the condensation heat transfer characteristics of R123 saturated steam outside single-tube at five levels were carried out. The condensing temperatures were 38 ℃, 40 ℃ and 42 ℃ respectively. The experimental results show that the experimental values of condensing heat transfer coefficient outside the light pipe agree well with the Nusselt theoretical value, and the maximum deviation does not exceed ± 10%. Both low-cost and serrated pipe can play a significant role in enhancing heat transfer, the strengthening ratio between 8 4 ~ 160, and serrated pipe performance is better than low-ribbed pipe. The experimental research also compares the condensation heat transfer characteristics of R11 and R123 outside the strengthened tube, and proves that it is feasible to use R123 instead of R11 condensation heat transfer.