最近,有的国家在大型(容积128米~3)保温车上采用液氮制冷,并考虑用液氮及机械制冷,以控制货物间的大气含氮量。用液氮制冶的优点: (1)在经济上比机械制冷便宜30%～50%,主要是设备维修费用低; (2)构造简单,自采用平壁真空隔热铝板液氮罐后,增加了罐容积,可盛液氮1,500公斤,因此,保温拖车可连续运行12天,而液氮装备所占体积与机械制冷大约相等; Recently, some countries have adopted liquid nitrogen refrigeration on large (128 m 3 capacity) insulation vehicles and considered the use of liquid nitrogen and mechanical refrigeration to control the atmospheric nitrogen content of the cargo. The advantages of using liquid nitrogen for metallurgy are as follows: (1) economically 30% ~ 50% cheaper than mechanical refrigeration, mainly due to low maintenance cost of the equipment; (2) simple structure, The tank volume is increased to contain 1,500 kg of liquid nitrogen. Therefore, the insulated trailer can run continuously for 12 days, while the liquid nitrogen equipment occupies approximately the same volume as the mechanical refrigeration.