[Refrigerated truck knowledge 2] The temperature of the container is unstable

In the process of transportation, large-scale supermarket-frozen frozen foods must rely on refrigerated trucks as carriers. In certain transportation, there will be a situation in which the temperature is required to drop rapidly. Yuhong will explain the unstable temperature of the refrigerated trucks.

Many users will have some troubles at this time, and the temperature of the refrigerated truck compartment will drop. How to solve the problem in this way?

1. The refrigerated truck has poor heat insulation or sealing performance;

The poor thermal insulation performance is due to the fact that the skins inside and outside the skin are not adhered to each other or the thickness of the insulation layer is insufficient, and the heat insulation and heat preservation effects are poor. It is mainly caused by improper selection of the thickness of the insulation layer during design or poor quality of the insulation material during construction. In addition, during the construction and use process, the thermal insulation moisture resistance of the thermal insulation material may be destroyed, resulting in the insulation layer being damp, deformed, or even eroded. The thermal insulation capacity is reduced, the cooling loss of the car body is increased, and the temperature of the car body is obviously decreased. Slow down. Another important cause of large cooling loss is poor cabin sealing performance, with more hot air entering the chamber from the leak. Generally, if condensation occurs on the sealing strip of the car door or the sealing wall of the car body, the sealing is not strict. In addition, frequent switching of the door or more people into the car together will also increase the cooling capacity of the refrigerated car body. Doors should be avoided as much as possible to prevent large amounts of hot air from entering the car. Of course, when the refrigerated car body enters the stock frequently or the quantity of the goods is too large, the heat load increases sharply, and it takes a long time to cool down to the prescribed temperature.

2. The frost on the surface of the evaporator is too thick or excessively dusty;

Another important cause of slower temperature drop in the car is the low heat transfer efficiency of the evaporator, which is mainly due to excessive frost or excessive dust on the surface of the evaporator. Since the surface temperature of the carbody evaporator is mostly lower than 0 ° C, and the humidity of the car body is relatively high, the moisture in the air is easily frosted on the surface of the evaporator, and even freezes, which affects the heat transfer effect of the evaporator. To prevent the surface of the evaporator from being too thick, it needs to be defrosted periodically. There are two methods of defrost, as follows:

1 stop defrost. That is to stop the compressor operation, open the door of the car, let the temperature of the car rise, and then restart the compressor after the frost layer is automatically melted.

2 flushing cream. After the goods in the car are carried out, the surface of the evaporator pipe is directly washed with tap water having a relatively high temperature to dissolve or fall off the frost layer. In addition to excessive frosting, the heat transfer effect of the evaporator is not good. The surface of the evaporator is too thick for long-term uncleaning, and its heat transfer efficiency is also significantly reduced.