Hi All, I am in a dilema taking a decision regarding heat exchanger. I have a sample heat exchanger made of stainless steel, my task is to design another heat exchanger with same area but using SA-106B metal and supplying same heat from the hot fluid. Fluid is thermal oil inside tube and outside will be open to a house full of lumber. Operating temperature will be around 350 F. Do these metals have same or negligible difference of heat transfer coefficient or thermal conductivity? I am not finding thermal conductivity of SA-106B metal at 350 F. Can someone help me with this issue? Thank you.
https://www.sciencedirect.com/search?qs=Heat%20Exchanger%3A%20Stainless%20Steel%20and%20SA-106B%20heat%20transfer%20coefficient&show=25&sortBy=relevance
SA-106B is low alloy steel, heat coductivity coefficient about 25-35 W/m2K, stainless steel is high alloy steel, heat conductivity about 15-20 W/m2K. If you need fine definided values of coefficients - search please data about low and high alloy steels.
Your heat exchanger will work best, than stainless steel sample.
Hi Rasel,
Difference in material only affects the thermal conductivity. The heat transfer coefficient on in- and outside of the tubes will not change.
Stainless Steel: thermal conductivity is 15 W/mK
C-Steel SA 106B: thermal conductivity is 50 W/mK
But to calculate thermal resistance wall thickness is needed: wall / conductivity.
Stainless steel will have thinner wall as the C-steel so difference in thermal resistance will be small.
Other topic: total capacity of the heat exchanger will depend on heat transfer coefficient inside tubes: depending velocity but thermal oil at 2m/s about 1500W/m2K, the wall resistance and the hea transfer coefficient outside the tubes.
But outside the tubes?? Medium is air?? Do you have fins outside tubes?When only plain tubes with air Heat transfer coefficient will be about 100W/m2K and the thermal resistance of material will have only a very small influence on the capacity of the heat exchanger. Sizes can be kept the same.
Do you want more info? please send me more data.
To have a correct judgment, someone needs the complete data sheet of heat exchanger. But, generally, if everything is just the same and only the material is changed, the error could be very low. Because, the effect of tube material on the overall heat transfer coefficient in an industrial application and with a heat exchanger with fluids in both sides will be lower than 10%.
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