How are the individual heat transfer coefficients for the hot side and cold side of a heat exchanger determined?
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I usually calculate the heat exchange area of a heat exchanger based on the overall heat transfer coefficient. This time, the buyer requires that the technical documentation provide the heat transfer coefficients for the hot side and the cold side separately, as well as the overall heat transfer coefficient. Please ask the experts to help answer, thank you
I work in the field of heating systems. Usually, we provide the manufacturer with the relevant parameters so that they can make the selection; during operation, we then use data to calculate the K value and determine how much it differs from the design values
1. For the heat transfer coefficient inside the tube, the flow model for circular tubes can be used; by determining the flow velocity within the tube, the Reynolds number, Nusselt number, and Prandtl number can be calculated. The convective heat transfer coefficient inside the tube can then be determined using the thermal conductivity of the fluid. For the convective heat transfer on the shell side, the flow model of a cylinder in flow can be employed, with the same procedure as that used for the tube side. The specific calculation formulas can be found in ‘Basic Principles of Heat and Mass Transfer’.
Find a book on heat exchangers to read; plate-type or shell-and-tube types are both fine. The heat transfer coefficient you mentioned is likely the convective heat transfer coefficient, which is different from the overall heat transfer coefficient K. For plate-type heat exchangers, it’s necessary to assume a temperature for the plates, and then use the overall heat transfer coefficient to verify the correctness of that assumed plate temperature – it’s quite complicated. If you’re asking about the formula, then the heat transfer coefficient = Nu number * (thermal conductivity / equivalent diameter)
The overall heat transfer coefficient is calculated, but can the individual heat transfer coefficient of one of the media be found? Just a quick question: what is the heat transfer coefficient of saturated steam at different pressures, in W/m2·℃? ? ?