When calculating the wall temperature of heat exchangers, the issue of determining the overall coefficient
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I work in equipment design and am not familiar with heat transfer. When calculating the wall temperature of heat exchangers, the data sheet provided by the foreign party shows three values for the overall coefficient: one for design conditions, one for clean conditions, and another for calculated values. Since these three values are different from each other, which one should be used? By the way, the overall coefficient should refer to the total heat transfer coefficient, right? The calculation of wall temperature is carried out according to the appendix in GB151. This post was last edited by weilegongzuo on 2009-3-9 at 14:35
What software do you use for calculating the strength of heat exchangers? This is crucial! If you are using SW6, it is recommended to use the calculated values as the metal wall temperature for the calculations.
Firstly, the overall coefficient is the total heat transfer coefficient. As for your design value, it represents the difference between the heat transfer coefficient estimated at the beginning and the one obtained later. The clean value refers to a K value that does not take into account the thermal resistances on both sides of the heat exchanger, while the calculated value is the result of the final calculations. When calculating the wall temperature, I prefer to use the calculated value, as it is derived through computation and should represent the actual value as well. Personal opinion; looking forward to the answers from below
The actual wall temperature should take the calculated value into account, while the other two values are the design value and the value without fouling thermal resistance. The wall temperature seems to be listed separately, not together with the overall heat transfer coefficient; I’m not sure. I wonder what software the original poster used for the design.
I couldn’t see the question clearly; my apologies. The over coefficient is the overall heat transfer coefficient; it includes values calculated from theoretical formulas, design values, and heat transfer coefficient values assuming no fouling. The calculated value should be used in practice