Board selection
The plate type or corrugated type should be determined according to the actual needs of the heat exchange occasion. For a large flow rate and a small allowable pressure drop, a plate with a small resistance should be selected, and a plate with a large resistance should be used. Depending on the fluid pressure and temperature, determine whether to choose a detachable or brazed type. When determining the plate type, it is not appropriate to choose a plate with a too small area, so as to avoid too many plates, the flow velocity between the plates is too small, and the heat transfer coefficient is too low. This problem should be paid more attention to for larger heat exchangers.
Selection of processes and runners
A process refers to a group of parallel flow channels in the plate heat exchanger with the same flow direction of the medium, and a flow channel refers to a medium flow channel composed of two adjacent plates in the plate heat exchanger. In general, several flow channels are connected in parallel or in series to form different combinations of cold and hot medium channels.
The process combination form should be calculated based on heat exchange and fluid resistance, and determined under the requirements of process conditions. Try to make the convective heat transfer coefficients in the cold and hot water channels equal or close to each other, so as to obtain the best heat transfer effect. Because the convective heat transfer coefficients on both sides of the heat transfer surface are equal or close, the heat transfer coefficient gets a larger value. Although the flow velocity between the plates of the plate heat exchanger varies, the average flow velocity is still used in the calculation of heat exchange and fluid resistance. Since the "U" shaped single-pass nozzles are fixed on the pressure plate, it is easy to disassemble.
Pressure drop check
In the design and selection of plate heat exchangers, there are generally certain requirements for pressure drop, so it should be checked. If the check pressure drop exceeds the allowable pressure drop, the design selection calculation needs to be performed again until the process requirements are met.
Calculation method
The calculation of heat transfer coefficient and pressure drop is calculated from the performance curves of various manufacturers' products. The performance curve (criterion correlation) generally comes from the performance test of the product. For the plate type lacking performance test, the reference correlation method can also be used to obtain the plate type criterion correlation according to the characteristic geometric size of the plate type. Some international general software use this method.
Selection software
Regarding the selection software of plate heat exchangers, generally each manufacturer has its own selection software according to its own plate type. Internationally used software includes HTRI, HTFS, etc. General calculation software is rarely published. Some domestic websites such as heat exchange support websites provide online calculation software for plate heat exchangers for reference.