About Fluid heat exchangers:
Fluid heat exchangers with a gas passing upwards through a shower of fluid (often water), and the fluid is then taken elsewhere before being cooled. This is commonly used for cooling gases whilst also removing certain impurities, thus solving two problems at once. It is widely used in espresso machines as an energy-saving method of cooling super-heated water to use in the extraction of espresso.
The choice of the allocation of the fluid to the shell side or tube side can have a significant impact on the performance, economics and maintainability of a heat exchanger. For most design work a balanced decision is required as the considerations can lead to opposite preferences. Some general guidelines are provided underneath:
Fouling
There are many mechanisms of fouling. Allocating the most fouling fluid to the tube side will be more favourable as mechanical cleaning of the inside of the tubes will be much easier. As the allowable velocity in the tubes is usually higher than at the shell side and a high fluid velocity causes attrition of the deposits, it is possible to reduce fouling by design.
Mechanical Design Pressure
It will be more econamical to put the medium with the highest maximum allowable working pressure at the tube side. If the shell side needs to be designed for a high pressure the wall thickness will increase making the heat exchanger more expensive.
Corrosion
If you need an expensive corrosion resistant material it will be more economical to place the corrosive fluid in the tubes as this will reduce the costs of the shell material or cladding.
