Influence of thickness and size of plate heat exchanger on pressure bearing
The stiffness of the plate refers to the ability of the plate to deform according to the requirements of the medium under different pressures under the clamping action of the fixed compression plate and the movable compression plate after assembly.
Under normal working conditions, in addition to sufficient strength, the plate needs to have a certain rigidity to control the deformation process of the plate, so that the heat transfer medium in the plate channel Uniform thickness ensures heat transfer efficiency. According to the principle of thermal expansion and contraction, the increase or decrease of temperature causes expansion or contraction of the sheet, but the expansion or contraction of the sheet is limited by the fixed pressing plate and the movable pressing plate. When the thermal expansion and contraction cannot be carried out completely freely, stress is generated, which requires the heat transfer sheet to have sufficient rigidity and pressure resistance. In the structural design of the slabs, it is often necessary to arrange the support points and increase the ribs reasonably. The stiffness of the slab depends not only on the density and accuracy of the position of the support but also on the length, width and thickness of the slab.
At present, the plate types of heat exchanger plates at home and abroad vary widely, and there are hundreds of forms. There are various types such as 1:2, 1:3, etc. in terms of aspect ratio. There are also 1:1, 1:4, 1:5, 1:6, etc. under special working conditions. Different working conditions use different aspect ratioses, and their pressure bearing capacity is not the same. After years of development and development of the plate type, the aspect ratio of the plate is one of the important factors affecting the stiffness of the plate.
For liquid and liquid conditions, the design of heat exchanger plates has a tendency to develop toward narrow and long. The narrow and long plate can effectively reduce the side flow phenomenon of the fluid, so that it can flow as uniformly as possible in the channel to enhance the heat exchange effect. In addition, it also provides favorable conditions for increasing the lateral stiffness of the sheet. The longitudinal stiffness of the plate can be ensured by 4 to 6 pairs of clamping bolts and fixed pressing plates and movable pressing plates; and in calculating the lateral stiffness of the plates, not only the deformation of the two plates after clamping, but also the force deformation after clamping. Also consider the liquid pressure and the tensile force of the gasket, as well as the deformation and misalignment of the plate support points. When the lateral stiffness of the sheet is insufficient to overcome the above deformation, it is possible that a leak occurs between the gasket and the sheet. Practice has proved that when the aspect ratio of the plate is about 1:2 5 and 1:3, the pressure bearing capacity of the plate heat exchanger can reach 2.5MPa, which is lower than this value, and the pressure capacity of the whole machine is 1.0-1.6 MPa.