What Is The Reason For The Frosting Of The Evaporator Of The Flake Ice Machine?

What is the reason for the frosting of the evaporator of the flake ice machine?

The icing of the evaporator of the flake ice machine can be roughly divided into two situations: icing caused by too low evaporation pressure and icing caused by low evaporation temperature caused by too small evaporation

In the first type, the opening of the expansion valve is too large, the evaporator is dirty, the air volume of the air cooler is small, and the defrosting is not complete, etc., all of which will cause frost on the evaporator and compressor. This phenomenon is generally caused by too little refrigerant. Everyone knows that the capillary throttling method is used for flake ice machines. This throttling method is immutable, that is to say, the pressure behind the capillary is Constrained by the influence of the condensing pressure before the capillary, the pressure after the capillary is reduced due to the decrease of the condensing pressure in the absence of refrigerant, and the lower the pressure can provide the evaporation under the premise that the orifice diameter cannot be changed The lower the pressure, everyone knows a theorem that the smaller the liquid supply, the lower the evaporation temperature and the smaller the cooling capacity! In this way, the part where the capillary enters the evaporator will freeze first, and then more and more evaporation temperature will get lower and lower, and the evaporation will be less and less. This will cause a vicious circle, causing the frozen part to be closer to evaporation At the outlet of the exchanger, this often happens because the indoor pipe temperature is at the outlet of the indoor exchanger, and the superheat of the return air increases due to too small liquid supply, so the supercooling protection that should work does not work ! (or due to the failure of the protective device)

The second phenomenon is mainly caused by the reduction of evaporation. This phenomenon is common such as the filter screen of the condenser is dirty and blocked. The speed of the fan motor is not enough, the surface of the exchanger is too dirty, etc.! If you carefully observe this phenomenon, the part with severe freezing is generally at the outlet of the evaporator. According to my analysis, when a certain amount of refrigerant liquid enters the evaporator, the normal cycle should evaporate at the outlet of the evaporator. In other words, it has basically evaporated, but because of the reduction of evaporation, some refrigerants have not been evaporated. These refrigerant liquids that have not evaporated are less and less at the end of the evaporator, which is similar to the low evaporation pressure. The phenomenon leads to the occurrence of icing, which generally causes overcooling protection! If the supercooling protection does not work, if it is broken, this phenomenon is relatively harmful, and it will cause the phenomenon of compressor wet stroke (liquid shock), because its occurrence is equivalent to excessive refrigerant filling ! The fluid supply is too large! Others are caused by lack of refrigerant!