Optimizing Efficiency of Solar Double-Pass Air Heater through Fluid Combination Approach

Department of Mechanical Engineering, College of Science & Technology, Royal University of Bhutan, 21101 Phuentsholing, Bhutan

^* Corresponding author: agarwala.cst@rub.edu.bt

Abstract

The solar air_heater (SAH) is one of the main devices that are used for harnessing solar energy for multipurpose functions. The double-pass solar air_heater (DPSAH) is an advanced model with ducts that transport the air to the two leaves of the loops. This technology is applied where space heating, thermal energy for drying processes, heat pumping applications, etc. are required. This investigation aims to determine the thermal characteristics of an air heater with a double-pass design that works by using CFD simulation. The study is to be carried out by (air flow rate and pressure distribution) measurement within the system. The process relies on the mixture containing both CO2 and O2 as the medium through which the process takes place. The CFD (Computational Fluid Dynamics) analysis results support that CO2 is an efficient working fluid resulting in better heat exchange. This is evident in the fact that supplementary thermal efficiency at the exhaust duct is 1.76% higher than that of air only. Additionally, the mixture of CO2 and air demonstrates increased efficiency with a 15.2% increase in efficiency relative to air alone. It is due to the different specific heat capacities of the gases that the mixture has a higher average specific heat. Therefore, the gas can store more energy, leading to higher thermal efficiency. The outcomes of this experiment demonstrate the possibility of gas combination for the enrichment of the DPSAH efficiency. This research enlightens on thermal energy systems and is an asset in improving the proficiency of solar air heating systems operation.