HEAT EXCHANGER

heat exchanger is a device built for efficient heat transfer from one medium to another. The media may be separated by a solid wall, so that they never mix, or they may be in direct contact.[1] They are widely used in space heating, refrigeration, air conditioning, power plants, chemical plants, petrochemical plants, petroleum refineries, natural gas processing, and sewage treatment. One common example of a heat exchanger is the radiator in a car, in which the heat source, being a hot engine-cooling fluid, water, transfers heat to air flowing through the radiator (i.e. the heat transfer medium).
Contents
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1 Flow arrangement
2 Types of heat exchangers
2.1 Shell and tube heat exchanger
2.2 Plate heat exchanger
2.3 Adiabatic wheel heat exchanger
2.4 Plate fin heat exchanger
2.5 Fluid heat exchangers
2.6 Waste heat recovery units
2.7 Dynamic scraped surface heat exchanger
2.8 Phase-change heat exchangers
3 Direct contact heat exchangers
4 HVAC air coils
5 Spiral heat exchangers
5.1 Construction
5.2 Self cleaning
5.3 Flow Arrangements
5.4 Applications
6 Selection
7 Monitoring and maintenance
7.1 Fouling
7.2 Maintenance
8 In nature
8.1 Humans
8.2 Birds, fish, whales
9 In industry
10 In aircraft
11 A model of a simple heat exchanger
12 See also
13 References
14 External links
[edit] Flow arrangement
Countercurrent (A) and parallel (B) flows
Fig. 1: Shell and tube heat exchanger, single pass (1-1 parallel flow)
Fig. 2: Shell and tube heat exchanger, 2-pass tube side (1-2 crossflow)
Fig. 3: Shell and tube heat exchanger, 2-pass shell side, 2-pass tube side (2-2 countercurrent)
There are two primary classifications of heat exchangers according to their flow arrangement. In parallel-flow heat exchangers, the two fluids enter the exchanger at the same end, and travel in parallel to one another to the other side. In counter-flow heat exchangers the fluids enter the exchanger from opposite ends. The counter current design is most efficient,