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Anonymous Poster

hext exchanger

02/25/2010 3:08 AM

Help requested to calculate the efficiency of a single pass shell and tube heat exchanger

Thanks.
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PWSlack
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#1

Re: hext exchanger

02/25/2010 3:09 AM

Is it lagged?

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PWSlack
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#2

Re: hext exchanger

02/25/2010 4:21 AM

Without knowing which fluid is which: the efficiency is equal to [the change in enthalpy of fluid 1 multiplied by its mass flowrate] divided by [the change in enthalpy of fluid 2 multiplied by its mass flowrate]. If the answer is over 100% then that is nonsense as the principle of Conservation of Energy doesn't allow it, so take the reciprocal of it to give an answer less than 100%.

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Massey 726
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#3

Re: hext exchanger

02/26/2010 6:29 AM

Hi Guest,

You have chosen one of the few thermal interfacing devices with virtually 100% efficiency. PWS asked is it lagged 'cos if you put enough lagging around it you could assume that energy in=energy out.

It doesn't matter whether its 1,2 or even 3 pass the answer will be the same only the approach temperatures will improve.

S&T cofigurations are great when there is a great difference between the primary and secondary flow rates;as the difference reduces you should be thinking in terms of plate heat exchangers.

Good luck.

Massey

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