I learned that this phenomenon is related to surface tension. I don't know if this flow characteristic contributes to the overall improvement of the heat transfer rate at an evaporator.
Thank you!
marangoni flow, is due to the marangoni effect which is generated by the gradients of surface tension due to the temperature gradients. if you can map the temperature field you can show if the effect shall be considered or otherwise is just minor. you may start by finding out the degree of saturation.
Dear Sayar, Thank you very much for helping. I have been observing considerable dropwise condensation upon evaporator fins and this condition is partially. Namely, fin surface temperature is variable along fin surface, and therefore condensation manner is different according to temperature gradients on surface and mapping temperature field is very difficult due to small fin space. Thank you again.
Surface tension also depends upon concentration Thus, Marangoni flows depend on both temperature and concentration gradients. Do you have films or droplets? What you describe sounds as local liquid-vapor (multicomponent?) equilibrium variation w. temperature affecting local mass transfer, and thus rates of drop growth. If you have droplets and by "condensation manner" do you mean the size/shape of droplets (max before rolling down, etc.), these may be affected by the local surface tension & contact angle, so sizes/shapes may be different for drops in different regions, even without significant gradients in individual drops. Hope this helps.
I am not sure I understand what you are looking for. Regarding your question about surface tension gradients, the answer is: Yes, it may influence te condensation process. For film condensation having thin condensate film, a positive surface tension gradient (with respect to temperature) may destabilize the film if the condensation rate is not very high, resulting in dropwise condensation.
You talk about condensation on evaporator fins, which confuses me a bit: If I interpret this as being an evaporator taking its heat from e.g. surrounding air (as in a heat pump) then I'm lead to believing it is partial condensation of water vapor from the surrounding air you observe. If so, the amount of condensation is normally small and dropwise condensation patterns are quite common.
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