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Heat transfer of glycol vs water in the same pipe

Heat transfer of glycol vs water in the same pipe

Heat transfer of glycol vs water in the same pipe

(OP)
I am interested in the effects of propylene glycol anti freeze on heat transfer in hydronic heating systems, baseboard and radiant floor heating. I have information on viscosity, density, Reynolds number, Prandtl number, Nusselt number and thermal conductivity for both fluids. I have used the Dittus-Boelter correlation for tubulant flow but am unsure of my results. Any information or sources would be appreciated.

RE: Heat transfer of glycol vs water in the same pipe

Your numbers at nominal room temp. to boiling look about right.  But dunno about comparisons below 32 F/ 0 C - isn't water no longer solid there, so comparisons of antifreeze solution to water lose meaning?

The only reason to add glycol is if there is a risk the system will be exposed to temp's. below freezing.  At higher temp's. glycol may reduce vapor pressure/boiling/cavitation concerns.  I have had people tell me they add glycol antifreeze for the corrosion protection...but why not just add corrosion inhibitors to pure water?

RE: Heat transfer of glycol vs water in the same pipe

If you can run inhibited water you'll have better heat transfer characteristics.  There's tons of info on the web comparing water, EG and PG.

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