Efficiency comparison between defrosting methods: A laboratory study on reverse-cycle defrosting, electric heating defrosting, and warm brine defrosting

Frost on the evaporator of a cold storage refrigeration system reduces cooling capacity and COP (Coefficient of Performance). Hence an energy-efficient defrosting process is crucial for economical operation. Various defrosting methods have been proposed in literature and their defrosting efficiency has been assessed. However, differing experimental conditions, e.g., variations in evaporator geometry and diverse air conditions, hinder accurate comparison across literature. Further, while electric heating defrosting (EHD) and reversed cycle defrosting (RCD) methods are widely studied, warm brine defrosting (WBD) method is rarely investigated. Despite this, WBD offers the potential to use low-temperature waste heat for defrosting, which reduces energy consumption drastically. Therefore, this study experimentally assesses the defrosting efficiency for EHD, RCD, and WBD on a single experimental setup, thus ensuring comparability. For the first time, low brine supply temperatures (10 & DEG;C/20 & DEG;C/30 & DEG;C) for WBD are investigated. Our results show that RCD reaches the highest defrosting speeds and has the highest defrosting efficiency between 56% and 61%, depending on air conditions. WBD at 10 & DEG;C and 20 & DEG;C exhibit low efficiencies of 16-29%. However, WBD at 30 & DEG;C has comparable efficiency to EHD (40-45%). The reported results can serve as a decision criterion in the design process of refrigeration systems.