Abstract: A significant amount of low-grade waste heat is discharged during industrial production processes. Utilizing heat pump technology to upgrade and reuse this waste heat can effectively reduce carbon emissions associated with industrial operations. When recovering industrial waste heat using heat pump systems, considerable temperature variations occur at both the heat source and heat sink sides, leading to pronounced irreversible losses. Non-azeotropic refrigerant mixtures exhibit a temperature glide during phase change, which enables better thermal matching within heat exchangers and consequently reduces irreversibilities in the heat transfer process. This study analyzes multiple refrigerants based on the characteristics of non-azeotropic mixtures and proposes a novel blend tailored for industrial waste heat recovery, guided by the principle of complementary advantages. Furthermore, a simulation model of a centrifugal high temperature steam heat pump for large-scale industrial waste heat recovery is established. The system performance of the selected non-azeotropic refrigerant mixture is compared with that of the conventional refrigerant R245fa under various conditions, including different condensation temperatures, waste heat flow rates, and heat source temperatures. The results show that the selected non-azeotropic blend R600a/R1234ze(Z)/R1336mzz(Z) in a molar ratio of 30%/20%/50% exhibits superior thermodynamic performance compared to R245fa. Under constant heat source conditions, the optimal condensation temperatures for R245fa and the mixed refrigerant are 107.5℃ and 110℃, respectively, with corresponding system coefficients of performance (COPh) of 3.36 and 3.94. At a condensation temperature of 110℃, the COPh increases by 20.45%. When the heat source conditions vary, the compression ratio is reduced by over 18%, and the COPh improves by 19.31% compared to R245fa, demonstrating the notable energy-saving potential of the proposed refrigerant mixture. Additionally, the study reveals that variations in heat source temperature have a more significant impact on system performance than changes in waste heat flow rate. These findings provide valuable insights for the selection of refrigerants and the operational optimization of high-temperature steam heat pump systems.

Key words: mixed refrigerants, waste heat pump, high temperature steam, system simulation

摘要： 工业领域排放了大量低品位余热，采用热泵技术将其提质后再利用是降低碳排放的有效手段。针对热泵回收工业余热时在热源和热汇端均存在较大温度变化，从而造成不可逆损失的问题，本工作结合非共沸混合工质在相变过程中具有一定滑移温度，可实现蒸发器和冷凝器中换热温度匹配的特点，筛选了一种适用于余热回收系统的非共沸混合工质，建立了针对大容量工业余热回收的离心式高温蒸汽热泵模拟模型，研究了选定非共沸工质与传统工质R245fa在不同工况下的系统特性。结果表明，选定非共沸混合工质R600a/R1234ze(Z)/R1336mzz(Z)以30%/20%/50%摩尔分数进行混合时，较R245fa具有更为优良的热力学性能。相同热源条件下，R245fa与非共沸混合工质的最佳冷凝温度分别为107.5和110℃，在最佳冷凝温度下两者系统能效比(COPh)分别为3.36和3.94；冷凝温度为110℃时，COPh提高了20.45%；在热源条件发生变化时，混合工质压比相较于R245fa降低了18%以上，COPh提升了19.31%，采用非共沸混合工质节能效果明显。

关键词: 混合工质, 余热热泵, 高温蒸汽, 系统模拟