# heat loss in pipe

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 April 8, 2015, 05:23 heat loss in pipe #1 Member   zduno Join Date: Dec 2013 Posts: 55 Rep Power: 5 Hello, I wanted to know how much heat is transfered through insulated pipe with water flowing in it, and then calculate temperature drop. I created a simple matlab script and got results which I am not confident about. Heat tranfered Q [J] should be equal to Q=(Tfluid-Tambient)/resistance resistance= (alpha1*2*pi*L*R0)^-1+(alpha2*2*pi*L*R1)^-1+log(R1/R0)/(2*pi*L*lambda) Therms corresponds to convection inside a tube, conduction through the wall and convection outside the tube. When I turn off ambient convective thermal resistance I get 1,4*10^3 J lost for 1m tube, when I turn it on I get only 70J/m heat transfer coefficients for water in pipe and air outside are equal to 2.75*10^3 and 10.21 W/m2/K It is weird that convection outside a tube insulates the tube so much ;( What do you think about those results? I am attaching matlab script if anybody wants to see it.

 April 10, 2015, 05:41 #2 Member   Join Date: Sep 2014 Location: Germany Posts: 76 Rep Power: 4 Hi, without considering the convection outside the pipe, you can't use Tfluid-Tambient as temperature gradient. T at the outside of the wall is greater than Tambient.

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