Value of the heat transfer coefficient
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Everyone, Q=KA△tm is used to calculate the heat exchange area; what value should k take? Thanks
K is calculated based on factors such as the type of fluid, flow rate, temperature, heat exchanger size, and material, rather than being arbitrarily assigned. If it’s “removal,” then heat transfer science is basically not needed.
But you need to give it a value first, before you can determine whether the k value is appropriate
This is a makeshift method, not the mainstream approach.
The values for heat exchange in different media vary. For example, the value for water is usually around 4000, but this algorithm is generally inaccurate; it merely provides a theoretical calculation of the area.
Please advise; I used to calculate it that way before
This post was last edited by wiseboy on 2015-8-3 at 11:42. First, a flow velocity within the tube is predetermined; based on this, a heat exchanger with a specific design is chosen, and then the corresponding K value is calculated – this K value is specific to that heat exchanger. If you think K is too small or there are other issues, change the assumed flow velocity inside the pipe and try again. Of course, you need patience and time; it’s quite tedious to determine a specific structure for a heat exchanger – otherwise why would heat exchanger software be so popular?
These days, heat transfer calculations are generally carried out using chemical engineering software, which makes things much easier; the value of K is calculated automatically. Of course, you’re right – it’s a manual calculation process that involves making continuous assumptions and performing reverse calculations.