Heat pump and solar panel: exergy method of thermodynamic analysis

Exergy analysis of the designed system is necessary to determine the degree of its thermodynamic perfection. The research goal was to evaluate the degree of increasing the efficiency of an installation on an experimental bench heat pump designed to study heat extraction from the back surface of a solar panel and its conversion into useful work. Two methods were analyzed – selection of a refrigerant and analysis of external sources. The analysis of the methods was used to compare the exergy efficiency of a modernized installation, including a heat pump and a solar panel as an additional low-grade heat source, with a laboratory heat pump installation before modernization. The authors performed exergy calculation, fluid selection, and analysis of external sources. It was revealed that the most effective method for assessing the exergy efficiency of new technical solutions is the method of analyzing the external sources. Calculations have established that the energy-efficient operation scheme of a heat pump together with a solar panel leads to the highest efficiency of 23.4%. However, this value is achieved with a large amount of sunlight, an air temperature of about 25℃ and a perpendicular incidence of sunlight on the panel. The exergy of electricity consumed by the electric motor compared to the heat pump before modernization was reduced by 8.92 kJ/kg, and the exergy efficiency of the modernized installation increased by 7.5%. The results prove the effectiveness of redirecting electrical energy to power the compressor. Installing a solar panel and heat pump will improve the environmental situation and save money due to the lack of fuel costs.

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