More Information.

LMTD and Heat Exchanger Calculator



1) LMTD (Log Mean Temperature Difference)



Counterflow
Parallel

$$LMTD \, = {(dt_i-dt_o) \over log_{e}(dt_i/dt_o)}$$
$$dt_i = pt_i - ct_o \,\,\,\,\,\,\, \,\,\,\,\,\,\, dt_o = pt_o - ct_i$$
$$dt_i = pt_i - ct_i \,\,\,\,\,\,\, \,\,\,\,\,\,\, dt_o = pt_o - ct_o$$

Heat Transfer Medium
cti
cto
Product
pti
cpo


Log Mean Temperature Difference
198.6



2) Heat Transfer Calculator


$$ A = {\dot{M}\,C_{pp}(\,pt_i - pt_o) \over U\,lmtd } $$

Ṁ Cpp U Cpc

Heat Transfer Rate
344.44
kW
Heat Transfer Area Required
3.02
m2
Heat Transfer Flow Rate Required
2.22
kg/hr
Ṁ is the mass throughput (kg/hr)
Cpp is the specific heat of the product (kJ/kg K)
pti Is the temperature of the product entering the heat exchanger1
pt0 Is the temperature of the product entering the heat exchanger1
U is the overall heat transfer coefficient of the heat exchanger (W/m2 K)
Cpc is the specific heat of the product (kJ/kgK)
LMTD is the log mean temperature difference1
1From the LMTD calculation above.

Simple Heat Transfer



This page started of as a simple LMTD (log mean temperature difference) calculation. I added he heat transfer calculation as an afterthought. The heat transfer. calculation calculates the area required to achieve the desired output temperature and gives good accuracy if you have an accurate value for the overall heat transfer coefficient.

If you're designing a heat transfer device you need to know the acceptable start up time, it is often this not the steady state operation that requires the highest energy transfer.

Click on this link If already you have a heat exchanger and you want to check the output temperature based on other parameters.

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