Refrigeration waste heat utilization for drying applications: a review

ABSTRACT

Cold chain industry has a vast potential for waste heat recovery. It is a matter of importance for energy efficiency point of view, as global energy demand is increasing day by day. Ample amount of low-grade energy is either unutilized or underutilized. The heat rejected by a Heat pump or refrigeration system emerged as a promising solution for dehydration by utilizing low-grade waste heat despite higher investment. As compared to solar drying technology, heat pump drying evolved as a reliable method regarding better process control, energy efficiency, and quality of the product to be dried. Energy utilized through the refrigeration system’s waste/exhaust heat recovery in combination with or without renewable energy source enhances the overall efficiency of the system and also reduces the cost. This useful review investigated and compared the research findings of waste heat utilization through heat pump and from condenser of refrigeration system on laboratory, pilot as well as industrial scale for drying of various fruits, vegetables, and agro products. Various drying parameters like drying rate, moisture content, Specific Moisture Extraction Rate (SMER), Coefficient of Performance (COP), Exergy efficiency, and temperature as well as humidity conditions inside the drying chamber were also reviewed to promote the technological advancement of energy utilization by commercial cold storage waste heat recovery.     

国内外环保型制冷方法的性能分析及新动态

本文介绍了目前国内外正在研究开发或投入使用的环保型制冷方法．分析了各种环保型制冷方法的原理、性能及适用场合,指出了环保型制冷方法目前尚存在的问题及突破方向．     

环保型吸附制冷中经济工质对法的实验与理论研究

针对环保型吸附制冷的特点，提出了一种新的评价方法，并利用该法对环保型吸附制冷中的两个关键因素工质对的选择及操作条件的优化进行了实验研究和理论分析，得出了一些有价值的结论，为环保型吸附制冷的应用提供了理论依据．     

库仑池的自动补液

大气中ＮＯ２、ＳＯ２湿法测定仪的核心部件是库仑池．工作时被测气体会不断带走池中电解液，而导致停机．本文所述就是库仑池的自动补液的一种方法