Thermal Performance of Low Cost Packed Bed Thermal Energy Storage Systems for Space Heating and Crop Drying Applications in the Rural Areas

Abstract

Low grade thermal energy is often required in the agricultural products, the conventional fuels most commonly used are diesel, petrol, bio-diesel, CNG, LPG, electricity, wood, agro waste etc. are available very costly day by day and are getting in the rural areas. The alternative is to use the solar energy thermal storage systems based on water is air required as a basic components in the low grade thermal energy utilization. A simple thermal analysis for open and close loop packed bed collector cum storage system has been carried out to study the performance of the system using different type of thermal energy storage materials such as rocks, pebbles, glass piece, stone pieces and fired brick. The effect of various parameter of packed bed, diameter of packed bed, porosity and mass flow rate on the volumetric heat transfer co-efficient, heat flux, efficiency of the system has been studied in details and time dependent periodic thermal model was developed. It was observed that fire brick gives better thermal energy storage effect than other storage material and hence it is recommended for open loop and close loop solar crop drying systems in the rural areas