CO2复叠制冷系统与载冷剂制冷系统适用范围研究

摘要

The employment of natural refrigerant have drawn widespread attention, since natural refrigerant are completely environmental⁃ly friendly and they have high potential in refrigeration application. Among them, the NH3/CO2 cascade refrigeration system and NH3 compression refrigeration system with CO2 as secondary refrigerant have been viewed as the most promising refrigeration methods in freezer and cold storage especially. Nevertheless, there is limited agreement on the scope of application for these two types of system since no strictly related investigation has been conducted. In this paper, the refrigeration performance of the two systems above is analyzed, and conclusion is drawn on the basis of practical engineering applications. The range of application for these two types of system is marked off and explained in detail, aiming at providing reasonable suggestion for design and optimization of CO2 refrigeration systems in the future. It is shown that NH3/CO2 cascade refrigeration system is more competitive when the evaporating temperature is below -25℃, and the max⁃imum suction pressure and the maximum discharge pressure of CO2 compressor should not be lower than 1. 97 MPa and 4. 07 MPa respec⁃tively.%鉴于自然工质制冷剂具有优良的环保特性，相关技术的推广应用越来越多地受到人们的关注，其中CO2与NH3被视为是最适合且最有潜力的自然工质。在冷冻冷藏领域，工业界和学术界使用最为广泛的制冷系统———NH3／CO2复叠制冷系统与NH3压缩CO2载冷剂制冷系统，这两种系统应用的工况范围并没有得到清晰而广泛的共识。对此，本文在常规商业冷冻冷藏应用温度区间内，分别对NH3／CO2复叠制冷系统及NH3压缩CO2载冷剂制冷系统的制冷性能进行分析，并结合实际工程应用条件，得出CO2复叠制冷系统与载冷剂制冷系统各自适合的工作范围，旨在为CO2制冷系统的合理应用提供参考。研究表明，在需求蒸发温度低于－25℃的场合宜采用NH3／CO2复叠制冷系统作为供冷系统，并且对于CO2压缩机，最高吸气压力应不小于1�97 MPa，CO2压缩机的最高允许排气压力也应大于4�07 MPa。