Experimental thermal stratification comparison of two storage systems

Abstract

The stratification distribution in an oil storage tank and in a sunflower oil thermal energy storage tank with a packed bed of spherically encapsulated meso-erythritol is investigated. The two systems are charged with flow rates of 3 ml/s, 6 ml/s and 12 ml/s respectively. For all the charging flow rates, the rate of rise in the stratification numbers is comparable. The packed bed system provides better stratification at a flow rate of 6 ml/s peaking to about 2.56 as compared to 2.06 for the oil TES unit. Generally, the peak stratification numbers for the packed bed TES systems are slightly higher at the higher flow-rates of 6 ml/s and 12 ml/s. The drop from peak stratification number for the oil TES unit was more pronounced as compared to the packed bed TES system due the larger thermal mass presented by the packed bed system, except for the highest flow-rate of 12 ml/s. The effect of mixing possibly due to turbulence is more evident in the oil TES tank than in the packed bed TES tank at the highest flow-rate of 12 ml/s which is reflected by the oscillations of the stratification number values.