How to compute Shell&Tube Heat Exchanger outlet temperature using E-NTU method ?

[miftahazhar]

Very need help with this problem. Properties which is known are fluid inlet temperature (both tube and shell), 1 shell pass and 2 tube pass, surface area, mass flow rate. With the unknown are overall heat transfer coefficient U and fluid outlet temperature. I want to compute fluid outlet temperature.

I had try calculate this problem. First I assumed U and then calculate NTU (UA/Cmin) and c (Cmin/Cmax). From NTU and c I calculate E (epsilon. ANd then I calculate heat transfer using Q=epsilon.Cmin.(Th,i-Tc,i). After that I can calculate fluid outlet temperature using :

Tc,o = Tc,i + Q/Cc
Th,o = Th,i + Q/Ch

From that I can calculate LMTD of this HE. And finally i can compute U using mc.Cp.(Tc,o-Tc,i)=U.A.LMTD. Last, i compare value of assumed U and calculated U. Problem is, no matter what assumed U value is, calculated U always same as assumed. Is there any mistake in my calculation ? Or maybe I should calculate using other method ?

*I had try calculate by assumed Tc,o but in the end its assumed value same as calculated one.

Tc,i = tube inlet temperature
Tc,o = tube outlet temperature
Th,i = shell inlet temperature
Th,o = shell outlet temperature

 

[victorpbr]

If you have tubes and shell diameter, you should be able to calculate U using geometric and conduction/convection constants. Sounds like a standard textbook question to me, take a look on some heat transfers books I'm sure you will find the expressions for U there.

PS: This question would be better suited for the Heat Transfer forum.

 

[SnTMan]

Heat Transfer Forum

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand