The plate heat exchanger is one of the most widely used equipment in the heat transfer equipment, it has a high heat transfer efficiency, compact structure, small footprint, installation, maintenance, combination of convenience features. Widely used in: the power, petroleum, chemical industry, metallurgy, machinery, light industry, food, medicine, electricity, painting, shipbuilding, mechanical and electrical, textiles, paper, heating and other industrial sectors.
Second, the plate heat exchanger heat transfer mechanism
The plate heat exchanger heat transfer mechanism is based on the heat transfer mechanism according to the laws of thermodynamics: "The heat is always from the hot object spontaneously pass to the low-temperature objects, two fluid temperature difference, it will have a heat transfer", exist in two temperature differential fluid in forced convective heat transfer process, the heat transfer plate surface corrugated wave structure optimization design, the heat exchange rate of 92%, even if the velocity of the fluid below the Renault prospective value, the fluid movement between the plates was also three-dimensional movement in which the fluid to the formation of severe turbulence, and reduce the boundary layer thermal resistance to heat transfer enhancement efficiency.
Third, the plate heat exchanger performance characteristics
At present, the plate heat exchanger has been applied in small refrigeration equipment (cooling water), and its application and will certainly further expand. This is mainly due to the plate heat exchanger with excellent heat transfer performance, small size, light weight, and continuously improve the safety and reliability of the plate heat exchanger. Overall, the practical application of good results. However, there are some problems.
The plate heat exchanger has a strong heat exchange capacity (heat transfer coefficient is several times more than conventional heat exchanger, a large heat transfer area per unit volume), and small size, light weight. Therefore, it has been subject to scientific researchers and users of all ages. However, the pressure resistance of the plate heat exchanger is not good, poor sealing performance, which restricts the application of the plate heat exchanger in the project. , Plate heat exchanger used in a cleaner working medium, the working pressure is not too high, not too harsh, not leak between the environment and the working fluid to produce a greater impact on the equipment leak requirements, such as used in civil hot water delivery systems and steam water exchange system.
At present, the refrigeration equipment using a plate heat exchanger, mainly small equipment, brazed plate heat exchanger, the main imports. As for the large chiller condenser and evaporator on a separate plate heat exchanger, it is theoretically feasible, but have not seen relevant reports. In other words, the plate heat exchanger in the refrigeration industry to further promote the use of certain concerns, its security and reliability, and its related issues to be further addressed.
A set of used refrigeration equipment, for example.
Fourth, plate heat exchanger in the practical application of which should pay attention to the following question]
Handle the evaporation temperature, cold water freezing point, the relationship of the cold water temperature. To ensure that the evaporation temperature of not less than the cold water freezing point, try to improve the cold water temperature, away from the cold water freezing point.
2, the plate for better performance, the pressure capacity of not less than the maximum pressure of system control. From the economic point of view, the use of the board for lower working pressure, should be retrofitted with a safety valve to ensure that the device does not overpressure.
3, install antifreeze blocking device is indispensable.
4, to improve the accuracy and speed of response of the temperature control, not only to control the water temperature, but also to control the cold water temperature.
5 equipment maintenance, improve system closed to reduce refrigerant leakage. When the device is unused for long periods, the refrigerant within the system should be drawn or pressed into the inside of the reservoir.
6, increase the water flow and the evaporator pressure drop control.
7, the cold water system to install filters.
8, change the low voltage parking for low-voltage operation protection, change the automatic reset, manual reset.
With the improvement of technology, improve the performance of plate heat exchanger. Plate heat exchanger in the refrigeration industry and will certainly become an increasingly widespread.
2, in the actual application process should take into account the characteristics of the plate heat exchanger, do and avoid weaknesses.
3, plate heat exchanger has a higher demand on the use of maintenance.