| 摘要: |
| 为优化复叠制冷系统的运行参数，本文对NH3/CO2复叠制冷系统进行了热力学分析，搭建了NH3/CO2复叠制冷系统实验台，获得了部分工况点的实验数据，并与采用不同压缩机等熵效率经验公式的热力学分析结果进行对比及误差分析，最终采用与实验数据相吻合的压缩机等熵效率经验公式，对系统的最大性能系数、最佳中间温度及最优级间容量比随系统蒸发温度、冷凝温度、复叠换热温差、高低温回路过冷度及过热度的变化进行了多工况下的理论分析。结果表明：蒸发温度对最大性能系数及最佳中间温度的影响最大，蒸发温度每增加5 ℃，系统最大性能系数提高约18.5%，最佳中间温度升高约2.23 ℃；冷凝温度对最优级间容量比的影响最大，冷凝温度每提高5 ℃，最优级间容量比增大约6.34%，而低温回路过热度对最优级间容量比的影响最小。建立了性能参数与工况的关联拟合公式，可为复叠制冷系统的优化运行提供依据。 |
| 关键词: 压缩机等熵效率 复叠制冷系统 热力学分析 最优级间容量比 最佳中间温度 |
| DOI： |
| 投稿时间：2021-05-07 修订日期：2021-09-16
|
| 基金项目:国家自然科学基金（51976095）资助项目。 |
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| Thermodynamic Analysis of NH3/CO2 Cascade Refrigeration System Considering Actual Compression Efficiency |
| Liu Li,Li Liansheng,Yang Qichao,Wu Jiawei,Zhang Yongli,Zhang Xiliang |
| (College of Electromechanical Engineering, Qingdao University of Science and Technology;Yantai AOWID Refrigeration Equipment Co., Ltd) |
| Abstract: |
| A thermodynamic analysis was conducted on an NH3/CO2 cascade refrigeration system to optimize the operating parameters. An NH3/CO2 cascade refrigeration system test platform was built, and the experimental data at some working points were obtained. Comparative and error analyses were performed using the thermodynamic analysis results of empirical formulas for different compressor isentropic efficiency. The formula that is consistent with the experimental data was used to analyze the maximum coefficient of performance (COPmax), the optimal intermediate temperature (TLC,opt), and the optimal inter-stage capacity ratio (nV,opt) of the system under variable temperature conditions. The temperature conditions included the evaporating temperature (Te), condensing temperature (Tc), cascade heat exchange temperature difference, and subcooling and superheating in the high-and low-temperature loops. The results show that Te has the greatest influence on COPmax and TLC,opt. When Te increased by 5 °C, the COPmax of the system increased by approximately 18.5%, and the TLC,opt increased by approximately 2.23 °C. Tc had the greatest influence on nV,opt, and the low-temperature loop superheat had the least influence on nV,opt. For every 5 °C increase in Tc, the nV,opt increased by approximately 6.34%. A correlation fitting formula between the performance parameters and working conditions is proposed, which can provide a reference for the optimization of operations in a cascade refrigeration system. |
| Key words: compressor isentropic efficiency cascade refrigeration system thermodynamic analysis optimum inter-stage capacity ratio optimum intermediate temperature |
