Performance study of transcritical CO2 heat pump integrated with ejector and latent thermal energy storage for space heating

Abstract

This study proposes a new transcritical CO2 heat pump integrated with ejector and latent heat energy storage system, and compares the performance of the system with and without energy storage equipment based on TRNSYS and experimental results. The results show that the new system operates more stably and is more conducive to space heating. Compared with the transcritical CO2 heat pump system with only ejector, the new system is more affected by the water flow rate and its performance can be improved by 18.53% when the water flow rate is 0.103 kg·s−1. The new system has more energy saving potential in low temperature environment, for which the utilization rate of primary energy and the primary energy ratio could reach 15.33 kgce·m−2 and 1.24, respectively. After thermo-economic optimization, it can be found that the minimum life-cycle cost of the new system is about 51.91 thousand CNY, which is reduced by 11.46% compared with the only ejector system. Therefore, the new system is superior to the previously transcritical CO2 heat pump systems both in terms of thermodynamic performance and economic performance. The research results are helpful to further promote the research and application of air source heat pump for space heating in low temperature area.