【作者】 孙勇军；

【导师】 王惠龄；

【作者基本信息】 华中科技大学 ， 制冷及低温工程， 2006， 硕士

【摘要】 论文详细介绍了非共沸混合工质汽液平衡的特点,并阐述了非共沸混合工质互补原理、节能原理及非共沸混合工质换热过程中滑移特性。从环境保护角度出发,提出在自然工质中选取具有与R22相近性能的丙烷作为替代工质的组元并结合替代混合工质热工性质的互补原理选取丁烷作为替代工质的另一组元。论文选取CSD状态方程计算混合工质的热力学参数并详细介绍了应用CSD方程所需的基本参数的来源。混合工质在换热过程中迁移特性是混合工质理论中极为重要而复杂的一部分。现有的各种理论模型及方法只适用于有限种类的混合工质或者一定的温度范围内。通过比较分析找出精度较高、形式较为简单的混合工质导热系数及粘度计算方法与公式。以非共沸混合工质在蒸发器中沿程温度分布变化所导致传热不可逆熵增为目标函数,建立混合工质与冷媒水在蒸发器中的稳态换热模型,以换热温差最小值为基准,分析计算得出二元混合工质R290/R600在不同组分比下的相对熵增,选取其中最小值对应组分比为最佳组分比。在制冷工况下分析比较了R22与所确定的新工质在单级制冷循环中的制冷系数,排气温度,质量制冷量以及压缩机功耗,混合工质具有替代R22的可能性,为R22的替代工质的选取与成分的确定提出了新的方法。更多还原

【Abstract】 This thesis introduces the characteristics of non-azeotropic mixed refrigerants’vapor-liquid phase balance in details and presents the mixed refrigerants’complementary theory, saving energy theory and the slippage identity in the process of heat transfer. From the viewpoint of protecting the environment, this thesis proposes that R290, which possesses the similar thermally physical qualities as R22, has the potential to be one of binary substituting refrigerants. Meanwhile, based on the complementary theory of thermal qualities, R600 has been chosen as the other one.The thesis select CSD state equation to compute the thermodynamic parameters and specifically introduce the source of basic parameters requested in the equation. The slippage identity is extremely complicated and significant part in the mixed refrigerants theory. The current various academic models and methods are suitable for limited types of mixed refrigerants and certain range of temperature. The relatively high precision and simpler format of computing methods and formulas for mixed refrigerants conductivity and viscosity are presented after the comparison.Focusing on the irreversible gain of entropy induced by temperature difference between non-azeotropic refrigerant mixtures and the cooled water, the steady heat transferring model between mixed working fluids and the cooled water has been constructed. Taking the minimum temperature difference as benchmark, an original method to compute the relative gain of entropy in different ratios of the mixtures of R290/R600 has been compiled, and the ratio with minimum gain of entropy has been selected as optimal component ratio.The thesis analyzes and compares the single stage compressing chilling circle performances of R22 with the selected mixed refrigerants in the following facets including COP, q0 , exhaust temperature and input power. The conclusion is that it is possible to replace R22 using mixed refrigerants; a fresh and efficient way has been advanced to select the compositions of substituting refrigerants and confirm the relative ratio in the thesis.更多还原