thought water is a good refrigerant, it is difficult to be used directly in a common compression refrigeration system due to its very low pressure and vapor density at the evaporation temperature.
由于水的蒸发压力低、比容大使得水作为制冷剂直接用于压缩式制冷系统还有很大的困难。
beijing university of technology has developed a miniature vapor compression refrigeration system as the cooling source of portable air-conditioning.