Sheet1Corrected Log Mean Temperature
Differencehttp://excelcalculations.blogspot.com
ParametersTh1 (K)400Th2 (K)170Tc1 (K)110Tc2 (K)190Shell-Side
Passes2
ResultsCorrection Factor0.9428089966LMTD119.7353400222Corrected
LMTD112.8875557859
Intermediate CalculationsP0.275862069R2.875X0.1988814304
Sheet2Corrected Log Mean Temperature Difference for
Shell-and-Tube Heat Exchangers
This Excel spreadsheet calculates the corrected LMTD for
shell-and-tube heat exchangers with multiple shell-side passes.
True log mean temperature differences are only valid in
double-pipe (or tubular) heat exchangers; hence for more complex
shell-and-tube arrangements, we have to muliply the LMTD by a
factor.
The equations used in the spreadsheet are taken from the work of
Bowman et al (1940) and are given below.
Note that R is the temperature change ratio of the hot and cold
streams, while P is the temperature change of the cold fluid
divided by the maximum temperature difference. F is the LMTD
correction factor.
Perrys Chemical Engineers' Handbook states LMTD correction
factors lower than 0.8 indicate inefficient heat exchanger design,
while the Heat Exchanger Design Handbook advises that the minimum
value should be 0.75.
Sheet3
