直接制冷系统 direct refrigeration system 直接膨胀供液制冷系统 refrigeration system with supply liqiud direct expansion 重力供液制冷系统 refrigeration system with supply liquid refrigerant for the evaporator by gravity 液泵供液制冷系统 refrigeration system with supply liquid refrigerant for evaporator by liquid pump 间接制冷系统 indirect refrigeration system 融霜系统 defrosting system 热气融霜系统 defrosting system by superheated vapour 电热融霜系统 eletrothermal defrosting system