Talk:Log mean temperature difference

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It's probably clearer to express the LMTD in terms of temperatures for 'left' and 'right' ends of the HE. This way the same formula applies to both co- and counter-current systems, and also the cross-flow case. Need to explain that the LMTD follows from a simple 1-D analysis (Incropera & DeWitt 4th Ed, sec 11.3.1).

- I agree with this, IMHO the whole first section should be scrapped and rewritten with a nice diagram and the use of 'left' and 'right' temperature differences. Also I think calling the log mean temperature difference a 'logarithmic average' is a bit of a misnomer. LMTD is just the mean temperature difference (ie, just an arithmetic mean), it just turns out the arithmetic mean using infinitesimal steps has a log in it (see the derivation section)! Calling it a logarithmic mean just confuses the issue and makes it appear more abstract than it actually is.

'F' is a 'correction factor'. But doesn't really come in to the definition of the LMTD.

Reasonable values of LMTD for typical types of heat exchangers would be useful.

[edit] Derivation of LMTD

Just added a quick derivation of LMTD as a distraction from study. Maybe someone can make a quick diagram up and fix any errors in the formulas (maybe fleshing bits out that I neglected). —Preceding unsigned comment added by 220.239.133.247 (talk) 12:43, 11 March 2008 (UTC)

good —Preceding unsigned comment added by 203.235.241.70 (talk) 03:08, 2 April 2008 (UTC)