Thermal Modeling of a Rooftop Photovoltaic/Thermal System With Earth Air Heat Exchanger for Combined Power and Space Heating

Abstract

Earth air heat exchanger (EAHE) systems are inefficient to provide thermal comfort in winter season for semi-arid regions. The performance of such systems could be improved by coupling them with other renewable energy sources. One of the renewable energy technology is rooftop photovoltaic/thermal (PV/T) air collectors which could utilize the incident solar insolation to obtain both electricity as well as useful heat. In the current paper, the thermal performance of an EAHE coupled with a PV/T system has been numerically investigated for climatic conditions of Pilani, Ajmer (India), and Las Vegas (U.S.). For the comparative analysis, a thermodynamic model has been developed and compared with experimental data available in the literature which seems to be in good comparison with the results. Further, a parametric analysis has been carried out for assessing the effect of different operating parameters. Results showed that for the winter season, the maximum cell temperature without any cooling goes up to 54.3 °C, 54.5 °C, and 44.4 °C for Pilani, Ajmer, and Las Vegas, respectively, while with cooling it drops to 43.4 °C, 44.2 °C, and 35.6 °C, respectively, for 0.053 kg/s flow rate. The heating capacity of the EAHE was observed to be improved with PV/T air collector by 23.47 Wh–298.74 Wh, 71.18 Wh–315.93 Wh, and 41.43 Wh–270.75 Wh for the Pilani, Ajmer, and Las Vegas, respectively.