What are the main functions of plate corrugations in plate heat exchangers?
a) Artificially induced turbulence
b) To increase the rigidity of the plates, forming a large number of metal contacts to withstand the working pressure when the plate bundle is compressed.
c) Enlargement of the heat transfer area.
In addition to the thermal performance, the plate heat exchanger is subjected to pressures of 2.0 MPa or more, which, in addition to gasket sealing problems, in the presence of fluid on one side only. This can lead to considerable non-uniform loads on the plate cross-section. The design of the plate corrugation must therefore ensure that, in addition to the heat transfer characteristics determining the corrugation cross-section, it is also necessary to ensure that the correct flow gap between the plates can be maintained at a differential pressure of zui. The correct flow gap between the plates can be maintained.
The strength and stiffness of the corrugated plate depends mainly on
a) the load at the corrugated contact between the two adjacent plates
b) the stresses and displacements within the corrugated sheet
c) the properties of the material being pressed, including the effect of temperature on the strength of the corresponding part.
d) Thickness of the sheet, which is also an important factor in terms of cost
e) the rate of contact of the sheet with corrugations, i.e. the accuracy of the sheet.
Apart from the corrugations, no part of the sheet in the unsupported area is sufficient to withstand severe deflection caused by pressure differences. Any local deflection of the plate will result in a reduction of the sealing load on the gasket and therefore its sealing performance.
In order to improve the rigidity of the plate and prevent deformation, it is essential that the plate has a large number of contact points in order to reduce the force load on each contact, which inevitably requires an increase in the manufacturing accuracy of the plate and an increase in the... This necessarily requires an increase in the manufacturing accuracy of the plate and an increase in the rate of corrugated contacts to prevent local deformation of the plate leading to seal failure.
If the contact of the corrugated contacts near the gasket groove is unevenly hooked, the process of pressing will lead to deformation at the local contact of the gasket groove, the compression of the corresponding part of the gasket will be reduced, and the sealing force will be lowered, which will inevitably lead to leakage during the test pressing process.
Similarly, uneven contacts in other corrugated parts of the plate will result in local deformation, which will inevitably lead to deformation of the other contact surfaces, and finally to deformation of the gasket groove, resulting in seal failure.
In addition, the plate precision high gasket deformation are hooked. Then the hardness of the gasket can be reduced. Gasket hardness is reduced, its elasticity is better, and thus the life of the gasket is longer.
This is one of the main reasons why the hardness of foreign plate heat exchanger gaskets is lower than that of domestic gaskets. The manufacturing accuracy of foreign companies' plates is generally higher than that of domestic plates. Although their plates are thinner, their hydraulic test pass rate is generally higher than that of domestic companies, regardless of the size of the plate and the amount of the assembled area, which is basically a pass.
In addition, the plate heat exchanger plate manufacturing accuracy involved in the plate bundle clamping process, to overcome the plate warpage, corrugated contact local deformation of the size of the load applied, and these loads directly affect the thickness of the clamping plate and the diameter of the clamping studs.
