We know that the temperature difference between the hot and COLD fluids in the heat exchanger VARIES from point to point. In addition various modes of heat transfer are involved. Therefore based on concept of appropriate mean temperature difference, ALSO called logarithmic mean temperature difference, the total heat transfer rate in the heat exchanger is expressed as

Q = U A [∆T]m

Where, U=Overall heat transfer co-coefficient [W/m2K], A=Area, M2
[∆T]m = Logarithmic mean temperature difference.

We know that the temperature difference between the hot and cold fluids in the heat exchanger varies from point to point. In addition various modes of heat transfer are involved. Therefore based on concept of appropriate mean temperature difference, also called logarithmic mean temperature difference, the total heat transfer rate in the heat exchanger is expressed as

Q = U A [∆T]m

Where, U=Overall heat transfer co-coefficient [W/m2K], A=Area, m2
[∆T]m = Logarithmic mean temperature difference.