The average temperature difference method for plate heat exchanger design:
(1)Calculate the unknown temperature or flow rate, calculate the unknown temperature or flow rate through the heat balance equation, Then calculate the heat load Q.
(2)Select the appropriate plate type and select the appropriate plate model according to the heat exchange load and flow rate. The choice of plate type depends on the specific working conditions. When the flow rate is large and the pressure drop is low, the plate type with low resistance should be selected; otherwise, the plate type withlarger resistance coefficient can be selected.
(3) Estimate the heat exchange area according to the heat load
(4)Select the number of passes and channels, initially select the number of cold and hot fluid passes and channels and calculate the flow rate.
(5) Calculate the average temperature difference.
(6) Calculate the convective heat transfer coefficient and the total heat transfer coefficient, determine the convective heat transfer coefficient of the cold and hot fluids separately, and then calculate the total heat transfer coefficient.
(7) Calculate the necessary heat exchange area. Recheck the heat exchange area.
(8)Verify the pressure drop. The allowable pressure drop is often a limiting factor in the design of plate heat exchangers. Efficient design always requires sufficient pressure drop. If the change of the heat transfer load, flow rate and allowable pressure drop cannot be coordinated regardless of the process layout, only an inefficient design can be made. If you are not getting a satisfactory design in the design, you can consider changing the board type.