Evaluating the performance of a solar-geothermal heat pump system for heating a greenhouse
Abstract
This study examines the simultaneous utilization of geothermal and solar energy for a greenhouse during the four coldest months of the year. The performance factor and exergy efficiency will be assessed throughout this period, and the variations in these parameters will be analyzed in relation to the temperature of the water entering the geothermal heat exchanger and the surrounding ambient temperature. In this study, the use of R22 (chlorodifluoromethane) with a mass flow rate of 0.1 (kg/h) provides important insights into their performance in an integrated system. This research presents a new method for optimizing a hybrid system by strategically integrating solar and geothermal energy, which results in increased power output and energy efficiency, and consequently reduced exergy efficiency. To achieve this objective, a suitable thermodynamic cycle is examined for greenhouse heating. By analyzing the laws of thermodynamics in relation to this cycle, the performance factor and exergy efficiency values are determined for the four coldest months of the year. The results show that the performance factor in January, February, March, and December was 4.136, 3.050, 3.048, and 4.205, respectively, and the exergy efficiency was 78.58%, 78.01%, 78.00%, and 78.62%. By examining the effect of the temperature of the water entering the geothermal heat exchanger on the coefficient of performance and exergy efficiency, it was found that by increasing the temperature from 6.7 °C to 9.5 °C, the efficiency of the geothermal system increases by 1.3%, which increases the efficiency of the entire system by 1.45%.