Performance analysis of a solid desiccant-assisted evaporative cooling system for automotive air conditioning in proton exchange membrane fuel cell vehicles

Abstract

Utilizing the wasted energy from fuel cells in useful applications is one of the most important approaches to enhance the systems' efficiency. The proposed system introduces a new air conditioning approach that uses the excess thermal energy from Proton Exchange Membrane Fuel Cells (PEMFC) to drive a Solid Desiccant-Assisted Evaporative Cooling (SDEC). The SDEC is used to provide the necessary cooling for vehicle cabins. A mathematical model is developed and validated for the integrated system. The effect of PEMFC characteristics, SDEC specifications, and ambient operating conditions on various parameters, including supplied air temperature and humidity, cooling capacity, and the sensible heat ratio (SHR) is examined. The parametric study shows that the increase in PEMFC current density and operating temperature relates to improving the cooling performance of the system. The SDEC characteristics study shows an inverse relationship between system performance and the airspeed passing through the desiccant wheel, with optimal cooling achieved at a relative rotating speed of 0.875 for the desiccant wheel. Although the supplied air temperature increases as ambient temperature increases, the system's cooling capacity is enhanced. Additionally, a decrease in relative humidity leads to increased supplied air temperature and cooling capacity.