How to determine the metal wall temperature during heat exchanger calculations
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When the process cannot provide the metal wall temperature, how is the metal wall temperature of the tube and shell sides determined in heat exchanger design?
Reply to 1# yangkunf: The inlet and outlet temperatures for the tube side and shell side of the heat exchanger should be specified in the design specifications provided by the process requirements.
The process specifies the conditions of the medium, and then calculations based on heat transfer theory are performed to determine the temperature distribution on the tube side and shell side walls.
Rough calculation: The design temperature for the tube side is equal to the average of the temperature of the medium on the tube side and the temperature of the medium on the shell side. For the shell side, the design temperature takes into account whether there is an insulation layer; if there is one, then the temperature of the medium on the shell side is used, while if there is no insulation, then the average of the temperature of the medium on the shell side and the external temperature is used. Precise calculation: It is necessary to use the formulas provided in the appendix of GB151 for accurate calculations. However, nowadays there are software tools available for quick temperature calculations, and such tools are generally used in chemical process engineering.
Strictly speaking, the wall temperature should be determined based on heat transfer calculations. In practice, for lower temperatures, the temperature of the medium is generally used as a reference, while for higher temperatures, it is determined through experience or calculations. Additionally: Some standards provide certain definition ranges that can be used as a reference.