Subcooling control: a way to enhance the performance of condensers for hot water production with a high water temperature glide.

The use of subcritical cycles in heat pumps is a good solution for the production of hot water in heating applications with water temperatures up to 50ºC and temperatures glides around 5K. For domestic hot water production however, the temperature glide is much higher, e.g. 50K, the condensation process being quite constant in refrigerant temperatures, results in a low effectiveness of condenser. Transcritical CO2 cycles has a better performance thanks to the large glide of the refrigerant evolution at the gas cooler. Hence, a way to enhance the effectiveness of the condenser in a subcritical cycle is producing a large amount of subcooling. The paper first presents two different cycles in order to obtain the desired subcooling and the experimental test rig. Finally, some preliminary results of COP are given for different operating conditions, such as the inlet water temperature at the condenser and degree of subcooling.

在热泵中采用亚临界循环（subcritical cycles）是制备热水的有效方案，适用于热水温度不超过50℃且温度滑移约为5K的供暖场景。然而，在生活热水制备中，温度滑移显著更高（例如50K），且冷凝过程中制冷剂温度保持相对恒定，导致冷凝器（condenser）效率较低。跨临界CO₂循环（transcritical CO₂ cycles）的性能更优，这得益于气体冷却器（gas cooler）中制冷剂变化的大滑移特性。因此，提升亚临界循环中冷凝器效率的一种方法是产生大量过冷（subcooling）。本文首先介绍了两种不同的循环以获得所需的过冷度，并描述了实验测试装置（experimental test rig）。最后，本文给出了不同运行条件下性能系数（COP）的初步结果，例如冷凝器入口水温及过冷度。