PERFORMANCE ASSESSMENT OF BASALT STONE AS HEAT STORAGE MATERIAL FOR SOLAR THERMAL SYSTEM

Abstract

In this study, basalt stone availability as storage material in the sensible heat storage method and the effect of heat transfer fluid flow rate were investigated. The experiments were carried out at three different flow rates, and measurements were taken at intervals of ten minutes for three days for each flow rate. Analytical results also show that the heat transfer to the water at 15 L min-1 is 660.5 W on average. On the other hand, it was determined that the average amount of heat transferred by the fluid at 30 and 45 L min-1 is 2339.9 and 2626.3 W, respectively. These results revealed that the increase in the intake temperature caused an increase in the fluid amount of heat transferred. A multiple linear regression model was created to determine the mathematical relationship between the inlet temperature and flow independent variables. Fluid heat transfer dependent variable and heat transfer values calculated by the generated model are found linear. It is seen that the amount of heat stored by the heat storage material decreases with the increase of the water flow rate. As a result of the calculations made, the water flow's heat storage efficiency adjusted at 15, 30 and 45 L min- 1 was found 43.1%, 9.5% and 6.5%, respectively. According to these results, it is concluded that the water flow rate as low as possible in such heat storage systems will increase the efficiency of the heat storage. Besides, the volumetric heat storage capacity of basalt stone was determined as 3417.3 kJ m-3 oC-1.