Thermodynamic analysis of a solar-fed heat upgrade system using the reverse air brayton cycle

Abstract

This analysis focuses on exploiting solar energy to meet industrial energy needs. It is based on upgrading solar heat production using surplus electricity from renewables to generate high-temperature industrial process heat. The approach involves the use of efficient evacuated flat plate solar thermal collectors coupled with a thermal storage tank to power a reverse air Brayton heat pump for high-temperature heat production. A Matlab algorithm has been developed to dynamically analyse energy balances across the system. The analysis is conducted for the location of Komotini, Greece and the results regard the operation of a system for a typical summer week. For the baseline design point with a 1000 m² collecting area and 50 m³ thermal tank volume, the average daily process heat production for the industry is 8.63 MWh, while the average daily coefficient of performance (COP) for the heat pump is 1.478. Moreover, the present work includes results regarding the parametric performance of the system for different combinations of collecting area and thermal tank volume. It was demonstrated that with the optimization of the solar thermal collector area and thermal tank volume, the daily average COP can be increased up to 23.1 %. Finally, the influence of the units of transfer area of the heat exchangers on the coefficient of performance has been investigated.