Effect of Internal Heat Exchanger on Performance of Transcritical CO2 Systems with Ejector

The objective of this paper is to explore whether the use of an internal heat exchanger can further improve the performance of transcritical ejector systems with C02 as the working fluid. Instead of using a simplified thermodynamic cycle analysis, the approach taken here is based on a more elaborated and experimentally validated system model for a real mobile air-conditioning system for a typical mid-sized car. However, the modeling of the ejector within the system model was still based on some idealized assumptions. The results indicate that the use of an ejector significantly increases the performance compared to systems without ejector and without IHX. The performance improvement effect of the ejector is reduced when the conventional system has an IHX. However, in comparison to a conventional system with IHX, the utilization of an IHX in the ejector system yields less performance increase than the ejector system not having an IHX. The high-side pressure correlations derived and presented here for all four systems can be used in further experimental and modeling work to maximize the cooling capacity and COP, respectively.