Board type selection
The plate type or corrugated type should be determined according to the actual needs of the heat exchange occasion. If the flow rate is large and the pressure drop is small, the plate type with low resistance should be selected, otherwise, the plate type with large resistance should be selected. According to the fluid pressure and temperature, determine whether to choose a detachable type or a brazed type. When determining the plate type, it is not advisable to choose a plate with a single plate area that is too small, lest there are 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 process and runner
The process refers to a set of parallel flow channels in the same flow direction of a medium in the plate heat exchanger, and the flow channel refers to the medium flow channel composed of two adjacent plates in the plate heat exchanger. Generally, several runners 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 get the best heat transfer effect. Because the convective heat transfer coefficient on both sides of the heat transfer surface is equal or close to the heat transfer coefficient to obtain a larger value. Although the flow velocity between the plates of the plate heat exchanger is not equal, the average flow velocity is still used in the calculation of heat exchange and fluid resistance. Because the "U"-shaped single-flow pipes are fixed on the compression plate, it is convenient to disassemble and assemble.
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 re-calculated until the process requirements are met.
Calculation method
The calculation of heat transfer coefficient and pressure drop is calculated from the performance curve of each manufacturer's product. Performance curves (criteria correlation) generally come from product performance testing. For plate types lacking performance testing, the reference size method can also be used to obtain the standard correlation formula of plate type according to the characteristic geometric dimensions of the plate type. This method is adopted by some general software in the world.
