Energy, exergy and economic evaluation of a solar enhanced ejector expansion heat pump cycle

Recently, heat pump technology has become the preferred method in drying field. However, most existing heat pump cycles use the single-stage vapor compression with expansion valve, which has the problem of large throttling loss. The use of ejector in the heat pump cycle can recover part of the expansion work and enhance cycle performance. Therefore, this paper proposes a solar-enhanced ejector expansion heat pump cycle (SEEHP) for drying application. Based on the conventional ejector expansion heat pump cycle (EEHP), the introduction of solar energy could not only improve the heating capacity of the cycle, but also improve the performance of the ejector. The energy, exergy and economic evaluation methods are used to theoretically analyze the EEHP and SEEHP. Compared to the EEHP, the energy analysis shows that the SEEHP with R134a refrigerant has a 23.64%–39.82% increase in heating coefficient of performance (COP_h) and 32.79%–33.96% increase in volumetric heating capacity (Q_cv) for the given condensing temperature range. Exergy analysis results reveal that the exergy destruction of SEEHP is mainly concentrated in the solar collector, indicating that the solar collector has the greatest potential for optimization in practical application. Economic analysis shows that investing in solar energy in the SEEHP is beneficial.