Five commonly used thawing methods include water immersion (WT), lotic water (LT), ambient temperature (AT), refrigerator (RT), and microwave (MT) thawing. WT, LT, and AT cannot maintain a specified constant temperature during thawing, whereas MT consumes substantial energy. On the basis of the shortcomings of the above methods, a constant temperature water immersion thawing system using fixed-frequency refrigerator compressor casing heat storage (CWT-CCTS) is designed. The CWT-CCTS recycles the waste heat of the compressor casing and uses the heat to thaw frozen food in constant temperature water. The new system not only provides a new heat source for thawing but also reduces the overall energy consumption and noise of the system during operation. Under a stable full-load operating condition of the refrigerator, CWT-CCTS can reduce the compressor casing and discharge temperatures by 3.8°C and 2.5°C, respectively. The water loss rate of CWT-CCTS is only 15.9% of MT, demonstrating a decrease of 84.1%. In terms of thawing, the maximum power consumption saved by the device is 516.79 kW·h per year in comparison with MT, and the cost of the device can be recovered after 178 days of use KEYWORDS compressor casing, constant temperature water, heat storage, phase change material, water immersion thawing
| INTRODUCTIONOwing to the improvement of living standard and the fast pace of life, customers not only require a variety of food types but also gradually start to pay attention to the preservation quality, flavor, and nutritional ingredients of food. Food-freezing technology has rapidly developed in recent years to meet the requirements of people. Frozen food must be thawed before processing. At present, the most common methods of thawing are MT, WT, LT, RT, and AT. The thawing speeds of WT, LT, RT, and AT are low. Although the thawing speed of MT is high, this approach consumes an enormous amount of power. 1 A common shortcoming of WT, LT, and AT is that they cannot accurately control the thawing temperature, thereby leading to the decline of food quality. Therefore, many researchers have conducted in-depth research on various thawing methods.Li 2 investigated the effect of various freezing and thawing combinations on the quality preservation of Pleurotus eryngii (king oyster mushroom). MT showed the most rapid thawing time, followed by LT and AT for