Fluid heat exchangers

This is a heat exchanger 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 machine as an energy-saving method of cooling super-heated water to be used in the extraction of espresso.

When selecting a heat exchanger technology, coolant compatibility with wetted surface must be considered. A copper fluid path is compatible with water and most common coolants used within heat exchangers. A stainless steel fluid path is necessary when using deionized water and other corrosive fluids. Aluminum heat exchangers offer excellent performance with ethylene glycol/water solutions (EGW), oils, and other fluids, but are not compatible with untreated water. The table below shows fluid and heat exchanger compatibility.