Energy and exergy efficiency analysis of solar driven ejector–compressor heat pump cycle

• A solar driven ejector compression heat pump cycle is proposed.
• Ejector model considering secondary flow pressure drop is established.
• Energetic and exergetic methods are carried out to analyze the system performance.
• The solar driven ejector could effectively improve system heating performance.

This study presents a solar driven ejector compression heat pump cycle (SEHPC) for air-source heat pump water heater application. The proposed cycle utilizing solar radiation to drive an ejector could effectively lift the suction pressure of the compressor and enhance the system heating performance. The thermodynamic investigations on the performance characteristics of the SEHPC using R134a and R1234yf as the refrigerant are performed with energetic and exegetic methods, and the comparative analyses with the conventional compression heat pump cycle (CHPC) are conducted. The simulation results show that SEHPC system yields a remarkable improvement of heating performance over the CHPC system. It is found that under the operating conditions considered, the system COP, heating capacity and heating exergy output could be improved by 15.3%, 38.1% and 52.8% over the conventional heat pump system, respectively. The largest exergy destruction is generated in the ejector, which could amount to 25.7% of the total system exergy input, followed by condenser and evaporator. The performance characteristics of the proposed cycle show its application potential in air-source heat pump water heater.