Direct Contact Heat Exchangers
Direct contact heat exchangers involve heat transfer between hot and cold streams of two phases in the absence of a separating wall. Thus such heat exchangers can be classified as:
- Gas – liquid
- Immiscible liquid – liquid
- Solid-liquid or solid – gas
Most direct contact heat exchangers fall under the Gas- Liquid category, where heat is transferred between a gas and liquid in the form of drops, films or sprays.
Such types of heat exchangers are used predominantly in air conditioning, humidification, industrial hot water heating, water cooling and condensing plants.
| Phases | Continuous phase | Driving force | Change of phase | Examples |
|---|---|---|---|---|
| Gas – Liquid | Gas | Gravity | No | Spray columns, packed columns |
| Yes | Cooling towers, falling droplet evaporators | |||
| Forced | No | Spray coolers/quenchers | ||
| Liquid flow | Yes | Spray condensers/evaporation, jet condensers | ||
| Liquid | Gravity | No | Bubble columns, perforated tray columns | |
| Yes | Bubble column condensers | |||
| Forced | No | Gas spargers | ||
| Gas flow | Yes | Direct contact evaporators, submerged combustion |
Read more about this topic: Heat Exchanger
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