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

本课题利用CFD对高温CO2热泵引射器进行了实验和数值模拟研究。这项工作的重点是两个喷射器，其中一个取代了膨胀阀，另一个喷油器用于回油。在高温CO2热泵系统中，高温侧压力水平高于以往研究的CO2制冷系统中的压力水平。因此，可能会出现亚稳性等新效应。因此，需要对喷射器进行新的实验研究，并对IFT开发的CFD数值模型进行扩展。石油喷射器以前没有被研究过，因此需要对这种新型喷射器进行广泛的新的测量。CFD数值模型需要考虑在喷油器中流动的CO2-油-油混合物的流体性质，才能正确地描述混合物的流体性质。

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.