Case Study of a Hybrid Geothermal-Solar System

Abstract

The usage and management of renewable energy have become a topic of interest since existing literature suggests that it would replace fossil fuels. In this study, an analysis of a closed-loop hybrid geothermal-solar energy system is introduced to control air temperature. This can be used in different air-conditioning applications including greenhouses, living quarters, and buildings. Such a case study was carried out in Damanhur city, Beheira Governorate, Egypt. First, the air produced from the proposed hybrid system conditioned the air of a room with the dimensions of L 2m x W 2m x H 2m. Geothermal energy was used to transfer heat to/from an air stream flowing inside a 5 m long, 2 inches in diameter, and 5.3 mm thickness PVC pipe. The pipe was buried 2 m below the ground’s surface and was supported by a solar chimney during the winter for the natural draft of air stream. In addition, a numerical model was built with 9 closed-loop geothermal cases of different design conditions. The pipe’s diameter varied in different cases from 0.17, 0.35, and 0.65 m, while the total pipe length was 47, 64, and 87 m. After that, the air stream was supplied to a room with the dimensions of L 3m x W 3m x H 3m. The air was subject to a 1m long solar chimney at 45ᵒ angle on a horizontal plane. The results of the numerical model prove that the maximum room temperature difference, which is close to 5 ᵒC, can be achieved using a pipe with a diameter of 0.65 m, and a length of 87 m. The validation of the numerical model was carried out using experimental results.