Comparison between reverse cycle and hot gas bypass defrosting methods in a transcritical CO2 heat pump water heater

Performance study on solar assisted heat pump water heater using CO2 in a transcritical cycle

This study reports the numerical analyses of a CO2 transcritical cycle on solar assisted heat pump water heating system in which evacuated tube U-pipe solar collector is utilized as an evaporator. This simulation model can predict operating characteristics for moderate meteorological conditions of North Dakota. The main purpose of this work is to simulate the overall performance of the heat pum...

Field Evaluation for Air-source Transcritical CO2 Heat Pump Water Heater with Optimal Pressure Control

Several optimal discharge pressure correlations for transcritical CO2 heat pump in literature have been discussed in this paper. Most of them are related to the ambient temperature, the evaporation temperature and the gas cooler outlet temperature. A revised optimal discharge pressure model as the function of ambient temperature and water outlet temperature is developed based on earlier experim...

Comparison of Two Gas Coolers in CO2 Heat Pump Water Heater

Influence of Refrigerant Charge Amount and EEV Opening on the Performance of a Transcritical CO2 Heat Pump Water Heater

Besides compressor rotary speed and parameters of water flowing through gas cooler and evaporator, refrigerant charge amount and electronic expansion valve (EEV) opening are two important parameters that have significant effects on the performance of a transcritical CO2 heat pump system. In this study, the effects of refrigerant charge amount on the performance of a transcritical CO2 heat pump ...

Optimization of a transcritical CO2 heat pump cycle for simultaneous cooling and heating applications

Energetic and exergetic analyses as well as optimization studies of a transcritical carbon dioxide heat pump system are presented in this article. A computer code has been developed to obtain sub-critical and super-critical thermodynamic and transport properties of carbon dioxide. Estimates for irreversibilities of individual components of the system lead to possible measures for performance im...