Question

A system for the storage of thermal energy is to be designed using an underground tank of water. The tank is buried at a depth of 3 m and is a cube of 1 m on each side. The water in the tank is heated by circulating it through a solar energy collection system. A given heat input to the water may be assumed due to the solar energy flux. Characterize the design problem in terms of the fixed quantities and design variables. please solve and explain

Answer 1

For designing the above system, first we need to find out the how much solar energy can be generated and efficiency of solar energy collector system. That is actual amount of heat energy given to to the circulating water.

These heated water must have to release all these heat energy inside storage tank.

There will be two types for heat exance inside storage tank that is 1)Direct contact heat exchange

2)Indirect contact or water flowing through tubes

If direct contact or mixing of water will takes place then more entropy will generated hence losses are high.

As tank is burried the heat energy loss to surrounding need to calculated by finding the conduction phenomenon.( as no convection and radiation possible)

For that initial temperatures, thermal conductivities,all the parameters will required.