Selection of design temperature for heat exchangers
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As stated in the title, the maximum operating temperature of the fluid in the tube side of the tubular heat exchanger is 110, while that in the shell side is 30; the operating environment temperature is at room temperature. When using SW6, what are the input design temperatures? If the wall temperature is calculated strictly according to the method of 151, what parameters are at least required? Is there a concise design temperature algorithm?
In my opinion, these parameters are insufficient; for a beginner’s card, the temperature of the heat exchange tubes should be the average of the average external temperature and the average internal temperature of the tubes, while the shell temperature should be the average of the external wall temperature and the internal wall temperature of the shell. Based on this, at the very least, one should know the inlet and outlet temperatures of the fluid inside the tube side, as well as the inlet and outlet temperatures of the fluid on the shell side. Additionally, it is necessary to know whether there is a thermal insulation layer outside the shell; in the case of insulation, the temperature of the shell itself is also important, while in the absence of insulation, the ambient temperature applies.
1. In the case of a U-tube heat exchanger, it is not necessary to consider the wall temperature; the design temperatures for the tube side and the shell side are calculated by adding several dozen degrees to the highest operating temperature. This temperature difference may be specified by the user, determined by the designer themselves, or decided by the process engineers. 2. In the case of a fixed-tube-sheet heat exchanger, the effect of wall temperature must be taken into account; the wall temperature is generally determined through heat transfer calculations carried out by process engineers.
In the calculation of fixed-tube-sheet shell-and-tube heat exchangers, an accurate value of the wall temperature of the heat exchange tubes is crucial. Calculations are carried out in accordance with Appendix B of GB/T151, and corresponding process parameters are required for such calculations. Without process data, it is impossible to make assumptions for calculation.
Import and export temperatures: Tube 110/70, shell 30/60. How are the calculations done for cases with and without insulation?