Experimental de-stratification and heat loss in a storage tank containing different thermal oils

Abstract

Simplified experimental de-stratification and heat loss characteristics of three thermal oils in a small storage tank are presented during 24-h low-temperature and medium-temperature cool-down cycles. Sunflower Oil, Shell Thermia C and Shell Thermia B are characterized experimentally during cool-down cycles. Temperature, stratification number and heat loss factor profiles are evaluated during low- and medium-temperature cool-down cycles. For low-temperature cool-down, Sunflower Oil shows the best performance with the lowest heat loss factor due its larger thermal mass as a result of its larger density. The best stratification distribution is obtained with Shell Thermia B which has the lowest density. For medium-temperature cool-down cycles, Sunflower Oil shows the best overall thermal performance with less heat losses due to its larger thermal mass which slows the rate of natural convection. Shell Thermia C has greater values of the stratification number for most of the medium-temperature cool-down cycle possibly due to its higher initial TES temperatures. Temperature profiles for medium-temperature thermal energy retention show a different behavior from the low-temperature behavior. Heat loss factor values for both low- and medium-temperature cool-down cycles are comparable suggesting that heat losses are similar.