Instead of the evaporator in the cold storage compartment of the top wall cooling pipe, the form commonly used in China is the top wall cooling pipe, which can limit the heat transfer from the outside to a certain extent, so that the frozen food consumes less during storage. Refrigeration and air conditioning installation is troublesome, defrosting is inconvenient, it is difficult to achieve automatic control, so there are also many shortcomings.

In recent years, countries such as Europe, America, and Japan have widely adopted air coolers to replace the bulky top wall cooling pipes. In Japan, for example, there are two ways to install the air cooler. The air cooler is installed outside the warehouse, and the cooling air is sent to the storage tank by the horizontal air duct. The other is that the air cooler is directly installed in the warehouse door. The upper part of the door bucket.

The air jet is attached to the flat top to make the cold air circulate naturally in the warehouse without a separate air passage, so that the cold air ejected from the air cooler outlet can be attached to the flat roof and returned to the floor along the top wall. In the middle walkway, the bottom of the air cooler is sucked again, so that the cold wind forms a thin-walled airflow in the frozen compartment, enclosing the outer structure of the entire warehouse, and the heat from the outside can be taken away in time. Moreover, when the door is opened, the hot air passed from outside the library can also be immediately sucked into the bottom of the air cooler. These avoid the fluctuations in the temperature between the freezes, thus reducing the dry consumption of food.

In the frozen storage, replacing the top wall pipe with the cooling fan has the following advantages: the steel consumption is small. Compared with the pipe, the amount of steel used in the cooling fan only accounts for the amount of steel used for the pipe. The construction of a small area is fast, and the chiller is only connected to the system piping at the site, and the installation is simple.