Experimental investigation of the time–temperature difference ( t –d T ) defrosting control method in frost-free household refrigerators

To improve the defrosting accuracy and the energy efficiency of frost-free household refrigerators, a novel time–temperature difference (t–dT) defrosting control method, based on experimental and theoretical studies, is proposed in this article. Experimental frosting and defrosting results verify the feasibility and applicability of the t–dT defrosting control method. The experimental data comparing two refrigerators at three different ambient temperatures show that the refrigerator applying the t–dT method had a shorter defrosting period and a shorter interval than those of the time–temperature (t–T) defrosting control method. Furthermore, the experimental results simulated real-life processes prove that the t–dT defrosting method could save more energy. Under the standard testing condition, the average total energy consumption including defrosting in the refrigerator applying the t–dT defrosting method is from 1.04 to 1.06 kW h within 24 h, and the ratio of defrosting energy consumption to the whole energy consumption is under 5%. The results indicate that the t–dT method is suitable for frost-free refrigerators and has more competitive performance than the t–T method.