PERFORMANCE OF DIRECT CONTACT LATENT-HEAT STORAGE UNIT

The performance of direct contact latent heat storage unit has been investigated in a glass column having an inside diameter and length of 0.2 m and 1.5 m respectively. Kerosene, as a heat transfer fluid, was bubbled through the continuous phase which was a solution of one of the hydrated salts: Na2CO3&middot10H2O, Na2SO4&middot10H2O, and Na2HPO4&middot12H2O. The continuous phase temperature at different heights together with the kerosene inlet and outlet temperatures were measured with time during both heat charge and discharge. Theoretical prediction of the performance of the unit has been achieved employing the model for drop with internal circulation which was used to evaluate the transfer efficiency. Thermal efficiency of the unit was found to increase with the larger column. A sharp decrease in the magnitude of the heat transfer coefficient was observed soon after crystallization started. The coefficient increased significantly at higher kerosene flowrates due to the formation of smaller bubbles.