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dRic2

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Hi, I'm looking to find a very very basic model to calculate the heat transfer coefficient in a tube with given heat power exchanged ##Q##. The fluid inside the tube starts sub-cooled (##T_{in}## is known) but exits the tube with a quality of steam around 0.15 (pressure is supposed constant). I'm willing to neglect all sort of effects that bubbles my induce on the heat transfer coefficients if they accumulate on the inner surface. I'd like just a simple rough estimation.

So I though to divide the problem in two part: first the sub-cooled water reaches saturation condition, and then it starts to boil. In the first part I could use ##Nu =0.023Re^{0.8}Pr^{0.3}##. As a first rough estimation I would chose an average temperature for the fluid, then I could refine the process in an iterative manner (considering the spatial dependence - but that is not my main issue here).

The problem is that I don't know how to treat the second part of the flow (where the water is partially boiling). I did quick research but the literature is very technical about this because it is a pretty studied but complicated problem. I was wondering if anyone knows a correlation used to get a very first rough estimated without getting too much into fluid dynamics (which I'm not an expert at).

Thanks Ric

So I though to divide the problem in two part: first the sub-cooled water reaches saturation condition, and then it starts to boil. In the first part I could use ##Nu =0.023Re^{0.8}Pr^{0.3}##. As a first rough estimation I would chose an average temperature for the fluid, then I could refine the process in an iterative manner (considering the spatial dependence - but that is not my main issue here).

The problem is that I don't know how to treat the second part of the flow (where the water is partially boiling). I did quick research but the literature is very technical about this because it is a pretty studied but complicated problem. I was wondering if anyone knows a correlation used to get a very first rough estimated without getting too much into fluid dynamics (which I'm not an expert at).

Thanks Ric

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