heat exchanger output temperature calculation


by hamish888
Tags: calculation, exchanger, heat, output, temperature
hamish888
hamish888 is offline
#1
May22-10, 08:11 PM
P: 1
1. The problem statement, all variables and given/known data

I have been asked to perform CFD simulations of a basic stainless steel cylindrical heat exchanger. I have to test a range of inlet temperatures and flow rates where external heat applied is constant.

I wish to perform basic hand calculation to verify my results by calculating the average outlet flow temperature but am unsure which equations to use for this. For example variables are as follows,

tank diameter 0.5m
feed pipe diameter 0.02m
tank surface temperature 135 degrees c
inlet flow rate 1l/min
Inlet temperature 50 degrees c

The tank thickness is not specified. The tank is heated by steam and the internal fluid is water.

2. Relevant equations

Thus far I have tried using variations on the Q=m(h2-h1) principle but have not been able to calculate this as i do not have enough information.

Should I be using Fw = Tw*pi*dl
then
Qw = qw*pi*dl=(Fw*cp*theta m)/Um

and how does qw differ from Qw?

I have basic knowledge of fluid flow and have not before this come into contact with thermodynamics.

Thanks in advance
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rock.freak667
rock.freak667 is offline
#2
May22-10, 09:12 PM
HW Helper
P: 6,214
What type of heat exchanger are you talking about? I only know how to analyze two, cross-flow and counter flow.

Both are analyzed using the LMTD method or the ε-NTU method.

So if your exchanger is one of those two, I can probably give you some help. But I am not sure as to the parameters in your equations that you posted.


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