R290/R744新型混合工质汽-液相平衡研究

Study on vapor-liquid phase equilibrium of R290/R744 mixtures

为了适应节能与环境保护的需求,研究了一种适用于自复叠制冷系统的新型绿色混合制冷工质(R290/R744)的汽液相平衡特性。根据相平衡条件采用PT状态方程结合Van der Waals混合规则推导出该混合制冷工质的相平衡计算式,通过软件编程计算了两种有工程实用意义的相平衡问题,一种是已知混合物压力和液相摩尔分数,计算泡点温度和气相摩尔分数;另一种是已知混合物压力和气相摩尔分数,计算露点温度和液相摩尔分数,并根据计算数据绘制了汽液平衡曲线。数据显示最大相对误差为4.840%,最小相对误差为0.005%。计算结果表明,采用给出的R290/R744混合制冷剂相平衡计算式具有较高的计算精度,从而为采用该混合制冷剂的自复叠制冷循环研究奠定基础。

In order to adapt to the requirements of the energy-saving and environmental protection,the main purpose of this study was to investigate the vapor-liquid equilibrium （VLE） properties of theR290/R744 mixtures.This refrigerant mixture can be used in auto-cascade refrigeration system. For this purpose,the calculation formulas of phase equilibrium of the mixtures were derived using PT state equation and Van der Waals mixing rules based on the phase equilibrium condition.According to the requirements of engineering applications,two phase equilibrium problems were calculated by software programming.One is to calculate the bubble point temperature and mole fraction in vapor phase using the pressure and mole fraction in liquid phase of the mixtures,the other is to solve the dew temperature and mole fraction in liquid phase using the pressure and mole fraction in vapor phase of the mixtures .The VLE graph of the mixtures was also finished.The comparison with references shows that the maximum relative error is 4.84% and the minimum one is 0.0005%,which indicates that the calculation formulas are accurate.The results of this research can be used as a foundation for auto-cascade refrigeration application.