利用状态方程,采用余函数法对混合制冷剂的比定压热容进行了推算。根据热力学普遍关系式推导了用通用性好、精度高的Peng-Robinson状态方程推算实际流体比定压热容的计算公式。以混合制冷剂HFC152a/HCFC22、HFC152a/HFC32和HFC134a/HFC152a为例,计算了其比定压热容,并与实验数据进行了比较。结果表明:液态HFC152a/HCFC22在温度区间303.15-353.15 K总平均偏差为12.90%;液态HFC152a/HFC32在温度区间313.15-353.15 K的总平均偏差为17.91%;气态HFC134a/HFC152a在温度区间298.15-423.15 K总平均偏差为2.93%。该法可以用于混合工质的比定压热容的理论推算。
The isobaric specific heats for the mixing refrigerants were estimated using equation of state and residual function method. According to the universal relation of thermodynamics, the calculation equation to estimate the isobaric specific heat of real liquid was conducted by Peng-Robinson equation with high accuracy. The isobaric specific heats of the mixing refrigerants HFC152a/HCFC22, HFC152a/HFC32 and HFC134a/HFC152a were estimated and compared with the experimental data. The results show that the total average deviation for liquid HFC152a/HCFC22 is 12.09% between 303.15 K and 353.15 K; for liquid HFC152a/HFC32 is 17.91% between 313.15 K and 353.15 K; for vapour HFC134a/HFC152a is 2.93%. The calculated method can be applied to estimating of isobaric specific heat for mixing working fluid.