Why does the chiller plate heat exchanger freeze and crack

Update:30 Jun 2021
Summary:

  The application of plate replacement in the refrigera […]

  The application of plate replacement in the refrigeration field is a cooler or an air-conditioning evaporator, which has long become a development trend in the refrigeration field. The plates of the heat exchanger will change with the service life, which will cause problems such as leakage, erosion, and freeze cracking. This is due to the large number of safe passages for machinery and equipment, and it takes many years of work experience to find accuracy. Today, I will tell you the reasons for the freezing and cracking of the plate heat exchanger of the chiller.
   In the whole process of specific application, due to the unsound design of the unit control system or the wrong operation of the customer, it is very easy to cause the failure mode of plate freezing and cracking. The actual reasons for the freezing and cracking of the plate heat exchanger of the chiller are as follows:
1. The filter device of the water inlet pipe of the plate changer is invalid, and the filter device is invalid, which will cause residues in the water inlet pipe to enter the heat exchanger, which will cause the heat exchanger to block, so that the water output of the plate changer that participates in the exchange of heat is less than the unit setting The minimum water output, so that the circulation is poor, and the parts with a large temperature difference will cause the ice block of the plate, which will cause the plate to burst and crack.
2. The saturated absorption temperature of the refrigerant is too low.
3. In winter, the protection of the electric heater is invalid. Under normal circumstances, the chiller will be shut down in winter. Because of the unique structure of the plate replacement, the internal refrigerated water cannot be completely drained, or the refrigerating temperature is too low when the customer consumes little heat. , The electric heater of the plate replacement surface layer starts to work to heat the internal refrigerated water to prevent the plate from freezing and cracking.
4. The maintenance of the flow switch is invalid. The key function of the flow switch in the chiller is that when the total flow of cold water is less than the preset value, the alarm shuts down to avoid freezing and cracking of the unit plate. Generally installed on the water outlet. If the flow switch equipment fails or the flow switch is blocked by human factors, the management program of the unit cannot immediately sound and shut down, causing the unit to continue to operate when the water output is less than the set rated current, and the refrigerant is replaced on the board. The internal air cools the refrigerated water again, which causes the plates to freeze and crack.
Secondly, when the plate changer is used as an air-conditioning evaporator in a refrigeration unit, the time when the vaporization temperature of the refrigerant in the saturated state of the plate changer is less than -10 ℃ should not exceed 20 seconds, otherwise, it is easy to cause the plate to penetrate and crack in an instant. , Causing freezing and cracking. Freezing and cracking of the plate heat exchanger of chillers is very common. We must find out the cause of the freezing and cracking in time. For this reason, we can carry out purposeful prevention to prevent the occurrence of freezing and cracking.