How to deal with the cold storage without defrosting

How to deal with the cold storage without defrosting

What should I do if the cold storage does not defrost? How to deal with this problem? The following will explain why the cold storage does not defrost and the solution.

　　 1. The dynamic process of frosting is roughly divided into the following stages:

　　1. Crystal growth stage: the frost develops from the frost, pipeline, and fin end line on the ground, from upstream to downstream of the airflow, and gradually forms a thin frost layer covering the windward surface of the tube fin. In the initial stage of frosting, the effect of frost increases the thermal resistance and decreases the air flow. At the same time, the thin frost increases the heat exchange area. As a result, the heating capacity is in a relatively flat arc shape with a high point;

2. Frost layer maturity stage: gradually expand and grow into a more uniform frost layer. During the expansion period, as the frost layer becomes thicker, the wind resistance increases, and the coil temperature (similar to the evaporation temperature change) decreases. The segment change rate maximum value;

　　3. The frost layer mature stage: the frost layer becomes dense or even frozen. At this time, the heat absorption of the evaporator mainly comes from the natural convection between the frost layer and the air, and the heat pump function deteriorates. Knowing the freezing process of frost, let's analyze the reasons that affect frost, such as evaporator structure, atmospheric environment (temperature, humidity), and air flow rate.

　　 Second, the order of influence on frost formation and air cooler performance is:

　　1, the temperature difference between the inlet air and the air cooler;

　　2, the humidity of the inlet air;

　　3, fin spacing;

　　 4. Inlet air velocity. When the ambient temperature is higher than 6℃, there is almost no frost; when the ambient temperature is -5～3℃ and the relative humidity of the air is high, the air cooler is prone to frost; when the ambient temperature is lowered, the moisture content in the air is reduced, resulting in condensation. The frost speed drops instead and freezes.

　　 Three, the solution

Some measures can be used to delay the formation of frost on the surface of the air cooler, such as increasing the front wind speed of the air cooler and the uniformity of refrigerant distribution, coating the surface of the heat exchanger with highly hydrophobic materials, etc., using electro-hydrodynamic methods to form around the heat exchanger Electric fields, magnetic fields and electromagnetic fields can increase the disturbance in the surface layer, and can also cause electrophoresis of the dielectric, change the shape and speed of water crystals, and are also a way to improve the heat exchange effect and delay the frosting. In practical applications and experiments, it is found that frosting mainly occurs in the first few rows of the fin tube bundle, so the design appropriately increases the spacing of the first few rows of fin tubes to delay the blocking effect of frost on the front fins and prolong defrosting cycle. These methods are generally completed in the early stage of the design. If the early design is not good enough to affect the frosting and defrosting effects, manual defrosting can also be done later. This is troublesome but the effect is good. Hope to help everyone.