Assess Heat Exchanger Performance

Writer： admin Time：2023-03-17 16:24:05 Browse：260℃

On several occasions during plant energy assessments, people have asked me to calculate the efficiency of a particular heat exchanger. But what does that really mean? For us mechanical and chemical engineers, despite everything we studied in school, we never discussed the energy efficiency of a heat exchanger. How could we have missed something that simple?

But actually, we didn’t miss it — efficiency, as the true definition goes, is the ratio of output divided by input. For all practical purposes, other than a very small amount of heat loss (probably less than 1%), heat exchanger thermal efficiency is 100%. Hence, very little improvement is possible and so we don’t worry about it. In fact, every time we do a heat balance, we inherently assume the thermal efficiency is 100% when we say the “hot side is equal to the cold side.” I also have seen people sometimes arbitrarily use a factor of 0.95, but I have no theoretical basis for it.