Investigation and Integration of CO2-Ejectors in Heat Pump Systems for Energy Efficient Design of High-Temperature Heat Pumps with High Heating Capacity

本课题采用CFD方法对高温CO2热泵喷射器进行了实验研究和数值模拟。工作重点是两个喷射器，一个代替膨胀阀，一个用于回油的喷射器。在高温CO2热泵中，高压侧压力水平高于先前研究的CO2制冷系统。因此，可能会出现亚稳态等新效应。因此，需要对喷射器进行新的实验研究，并对在IfT开发的数值CFD模型进行扩展。这种喷射器以前还没有被研究过，因此需要对这种新型喷射器进行广泛的新测量。数值CFD模型需要准确描述在喷油器中流动的二氧化碳-石油混合物的流体特性。

In the project, ejectors used in high-temperature CO2 heat pumps are investigated experimentally and numerically using CFD. The work focuses on two ejectors, one replacing the expansion valve and an oil-ejector used in the oil return. In a high-temperature CO2 heat pump, the high-side pressure level is higher than the one in the previously investigated CO2 refrigeration systems. Thus, new effects such as metastability might occur. Therefore, new experimental investigations of the ejector as well as an extension of the numerical CFD model developed at IfT is needed. The oil-ejector has not been investigated previously, thus extensive new measurements of this novel ejector are needed. Fluid properties of a CO2-oil-mixture, which flows in the oil-ejector, are needed in the numerical CFD model, which describes the fluid properties of the mixture correctly.