Should the potential difference be included in the pressure drop loss of plate heat exchangers?
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When we discuss the pressure drop loss of heat exchangers, should the head difference be included in it? Because in some cases with low flow rates, the pressure loss is only in the tens of KP; with a head difference of 1 meter, it amounts to 10 KP. Should this part be included in the pressure loss?
It doesn’t matter whether it’s included or not. However, it must be specified when including it; if not specified, it will be treated as not included.
As an important performance parameter of heat exchangers, I believe there should be corresponding standards specifying whether it should be taken into account or not. But I have reviewed many standards related to heat exchanger inspection, and none of them mention this issue.
1. Because the installation condition is uncertain: it may be installed horizontally, sometimes at an angle, but the angle varies as well ； 2. Strictly speaking, the pressure drop due to elevation difference is not a characteristic of the heat exchanger itself; when installing it, the owner often takes into account both the elevation difference of the heat exchanger and that of the connecting pipes.
Regarding the Euler criterion for heat exchangers, I believe that the effect caused by the potential difference should not be taken into account.
I think they should be treated separately: closed-loop systems don’t require this consideration, as for the resistance losses in closed loops only the frictional losses along the flow path and the resistance of the equipment need to be taken into account; open-loop systems, on the other hand, do require such considerations
When testing the performance of a heat exchanger, it is necessary to measure the pressure drop across the heat exchanger and derive the Euler equation; at this point, what is being determined is not the system resistance, but rather the characteristics of the heat exchanger itself, regardless of whether it is of open or closed type.