Zhang Ze, Hou Yu, Kulacki Francis A
State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an 710049, China.
Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN 55455, USA.
Entropy (Basel). 2018 Jan 18;20(1):31. doi: 10.3390/e20010031.
Comparative energy and exergy investigations are reported for a transcritical NO refrigeration cycle with a throttling valve or with an expander when the gas cooler exit temperature varies from 30 to 55 °C and the evaporating temperature varies from -40 to 10 °C. The system performance is also compared with that of similar cycles using CO. Results show that the NO expander cycle exhibits a larger maximum cooling coefficient of performance (COP) and lower optimum discharge pressure than that of the CO expander cycle and NO throttling valve cycle. It is found that in the NO throttling valve cycle, the irreversibility of the throttling valve is maximum and the exergy losses of the gas cooler and compressor are ordered second and third, respectively. In the NO expander cycle, the largest exergy loss occurs in the gas cooler, followed by the compressor and the expander. Compared with the CO expander cycle and NO throttling valve cycle, the NO expander cycle has the smallest component-specific exergy loss and the highest exergy efficiency at the same operating conditions and at the optimum discharge pressure. It is also proven that the maximum COP and the maximum exergy efficiency cannot be obtained at the same time for the investigated cycles.
本文报道了在气体冷却器出口温度从30℃变化到55℃、蒸发温度从-40℃变化到10℃的情况下，对带有节流阀或膨胀机的跨临界一氧化氮制冷循环进行的能量和㶲调查。还将该系统性能与使用一氧化碳的类似循环进行了比较。结果表明，一氧化氮膨胀机循环比一氧化碳膨胀机循环和一氧化氮节流阀循环具有更大的最大制冷性能系数（COP）和更低的最佳排气压力。研究发现，在一氧化氮节流阀循环中，节流阀的不可逆性最大，气体冷却器和压缩机的㶲损失分别位列第二和第三。在一氧化氮膨胀机循环中，最大的㶲损失发生在气体冷却器，其次是压缩机和膨胀机。与一氧化碳膨胀机循环和一氧化氮节流阀循环相比，在相同运行条件和最佳排气压力下，一氧化氮膨胀机循环具有最小的单位部件㶲损失和最高的㶲效率。还证明了在所研究的循环中，无法同时获得最大COP和最大㶲效率。
