【作者】 王兆华；

【导师】 沈永年；

【作者基本信息】 浙江大学 ， 制冷及低温工程， 2005， 硕士

【摘要】 R22在制冷行业的广泛应用和禁用日期的不断提前使得其替代工作日益成为工质研究的重点。从现有的条件来考虑,纯质替代存在一定局限性,因此选择混合物作为替代路线。 本文从保护大气环境的观点出发,依据替代制冷剂的选择标准,按照优势互补的原则,对多种HFC和HC类物质组成的混合物进行了研究。首先利用理论循环建立计算模型,分析各组元对混合物总体热工性能、安全性能以及环境性能的影响,并依据一定的优先原则对其进行筛选和配比优化, 确定了采用R32/R134a/R227ea(20/60/20wt)作为R22的直接充灌替代物。 理论计算显示其热工性质与R22相近,COP与R22相当,略有下降,q_v值略高于R22,而且相比R410最大的优势是其冷凝压力比较低,甚至低于R22。最重要的是其环境性能良好,ODP为零,GWP为1470(按照质量配比计算),低于R22及其主要替代物R407C和R410A。 新工质在按照国家标准GB5773-86建立的电量热器制冷剂循环测试系统上进行了性能测试,并与R22的实验结果进行了对比。分析表明,在整个测量温区内基本可以与R22匹配,其中COP高于R22,容积制冷量接近或略低于R22。而且新工质的最大优势是冷凝压力较低,排气温度也较低。可以在不对原系统作较大改动的情况下实现直接充灌。不利的一点就是温度滑移较大,因此在实际操作中必须小心细致,尽量避免成分泄漏或者补充充灌对系统的影响。如果能将原R22装置中的换热器改为逆流形式,从而充分用温度滑移,整个系统的效率将会进一步提高。更多还原

【Abstract】 Widely using of R22 in the filed of refrigeration and the date of phased out earlier make the project of substitute emphasis on working fluids study. Considering the existing condition, there are many difficulties in using the pure substance as substitute. So we chose the mixture as the substitute routine.Start form the viewpoint of environment protect, using the criterion of alternative refrigerant selection and according to the principle of combination, many mixtures HFC and HC contained are studied in this paper. At first a calculation mode is established based on a theory circle, then the effect of each composition on the environmental properties, thermal performances and safety of mixtures as a whole are analyzed. According to certain principle, optimization on mixture ratio is conducted and refrigerant mixture R32/R134a/R227ea(20/60/20wt) is determined as the alternative to R22 used in existing equipment at last.Theory calculation results show that the thermal characters of new working fluid match to R22, COP is slightly less than R22, q_v is more than R22 a little. Moreover its priority to R410 is lower condensing pressure, even below R22. The most important is that it is environmentally friendly, ODP=0, GWP=1470(calculated by mass ratio), both below the value of main alternative R407C and R410A.The performance of new working fluid is also tested on the electric calorimeter apparatus for refrigeration performance measurement designed according to GB5773-86, compared to the experiment results of R22. It shows that it can match to R22 both in COP and capacity. The disadvantage is the considerable great temperature glide, so it should be careful deal with, avoiding refrigerant leakage influence on system. If the heat transfer can be changed in reverse flow way, the efficiency of system can be greatly raised.更多还原