Interview QnA#3

When to use double pipe heat exchanger and shell and tube heat exchanger?

Answer

Double pipe heat exchangers are used when the heat transfer area is small say up to 14 m2. If we connect them in series to increase the heat transfer area it will require much space as well the pressure drop will be higher due to more fitings. Also we can’t increase no of passes for either side fluids.

The double pipe HE can’t be used for dirty fluids due to choking and cleaning is tougher. The advantage is it is simple to construct and easy to operate.

But in shell and tube HE, we can pack a large heat transfer area within a small volume. As the numbers of tubes are more in a shell and tube HE, we can expect a higher turbulence which will result in higher heat transfer rates. Dirty fluids also can be handled owing to

easy cleaning.