Thermal Behavior of a Simultaneous Charging and Discharging Concrete Bed During a Heating Cycle

Abstract

This study developed a mathematical model from consideration of the basic phenomena of heat transfer to predict the thermal behavior of a simultaneous charging, storage and discharging system during a heating cycle. A solution to the complex mathematical model was assumed in the form of a general equation for which the constants in the equation were determined. The mathematical model simulated an air packed bed storage system coupled to a flat plate solar collector which received intermittent solar radiation and supplied it in sinusoidal form to the packed bed. Finite Fourier series analysis with the first three harmonic terms was applied to the solution of the equation. Experiments were conducted by charging the packed bed system from a flat plate solar collector of area 1.5m2. The experimental results showed an average discharge temperature of 50.75 oC over the period of 7.00 hr to 17.00hr compared to the theoretically predicted average value of 50.40 oC.