Economic design of a rock bed storage device for storing solar thermal energy

This study deals with the optimization of design and operational parameters of a rock bed thermal energy storage device coupled to a two pass single cover solar air heater, i.e., charging time (⊖), rock bed size (flow length, H), and cross-sectional area for square cross section ( A R), rock size ( D R), air mass velocity per unit bed cross-sectional area ( G), and void fraction (ϵ). The optimization has been accomplished by investigating the effects of the above parameters on the total energy stored and the cost per unit energy stored in the rock bed for the winter climatic conditions of Delhi.