Performance of Sunflower Oil as a sensible heat storage medium for domestic applications

Experimental results evaluating the thermal performance of edible Sunflower Oil as a heat storage medium for domestic cooking applications are presented. The thermal performance of Sunflower Oil is evaluated during charging, 24 h heat retention and discharging cycles. Results of charging reveal that high temperature charging is the most viable option. This is because it results in higher energy, higher exergy, higher exergy factor and higher stratification number values. The charging efficiency is found to only represent the rate of heat transfer and it indicates nothing about the quality of the stored energy. The optimal charging time proposes that charging be continued until a point when the stratification number drops to 80% of its peak value. Heat retention results during 24 h show that high temperatures result in more heat losses during the cool-down heat retention processes. An optimal heat retention temperature is also suggested by the results. An optimal discharging flow-rate is also suggested by the discharging results. This is a compromise between obtaining a high rate of heat transfer and using the stored energy more effectively. The stratification number profiles show initial rises during the discharging cycles since the top temperatures drop at slower rates as compared to the bottom temperatures which results in larger thermal gradients as compared to the initial thermal gradients.