Absorber Type Optimization for Night-Shift Operation of Solar Air Heater

Abstract

In the current study, the effect of using heat storage materials aimed at the night shift operation are studied by simulation tools. Finite Volume Method (FVM) is used as a method to discretize the governing equations in the 2-D domain, and the RNG K-ε turbulence model is applied for simulation. Effect of absorption type based on five different martials such as Aluminum, Water, Asphalt, Graphite, and Sand on performance of solar air heaters (SAH) is carried out thermally. The results presented that the optimum material to obtain the maximum difference in temperature (38.32 K) between the absorber and the surrounding occurs once the Asphalt is used while, the Sand is the worst case which is (31.71 K). Following the focus is on the best absorber for the night time operation. The Lamped Parameter Analysis is applied to the time required to dissipate the heat energy from the storage layer to reduce to the assumed final temperature of 5-degree difference (Higher) than the ambient. After solving the transient equation, it is found that Water can operate the system for a longer period (4.31 hrs.) as well as the Graphite can operate the system for a shorter period (0.46 hrs.). Then ten different velocities at entry section is used to consider the influences on the system performance. The outcomes show that the velocity has a significant effect on the outlet temperature and operation period for night time.