Heat Exchangers
Description
Heat exchangers transfer heat between two physically separated fluids over a metallic surface. A typical example of a heat exchanger is the radiator in a car. Heat exchangers perform various processes such as heating, cooling, condensing, evaporating, recirculation and heat recovery. The principle of operation heat exchangers is based on the fact that the heat energy has to meet equilibrium. Heat exchangers have a metal wall (conductor) which divides two fluids. When hot fluid flows on one side of the wall, it transfers heat to the cooling fluid on other side in order to maintain equilibrium. Mostly water is used as a cooling fluid as it is a good conductor of heat. Aluminum, steel, titanium, cast iron, bronze or copper are some of the materials used for fabricating heat exchangers.
Types
Brazed heat exchangers
Shell and tube heat exchangers
Shell and coil heat exchangers
Air cooled heat exchangers
Plate heat exchangers
Phase change heat exchangers
Adiabatic wheel heat exchangers
Recuperative heat exchanger
Evaporative heat exchangers
Based on flow
Parallel flow heat exchangers
Cross flow heat exchangers
Counter flow heat exchangers
Based on function
Advantages
Limitations
Applications
Heat exchangers are employed for space heating, chemical processing, refrigeration, air conditioning power production, electrical systems, and mechanical systems. Other applications are boilers, condensers, preheaters in power plants, radiators in internal combustion engine, ventilating, heating in air conditioning systems. Brazed heat exchangers are used for hydronic systems such as radiant floor heating, swimming pools, ice and snow melting. They are also used in industries such as paper and pulp, steel industries, automotive, water treatment plants, marine, pharmaceutical, oil refineries, food processing, in nuclear system reactions, in aircraft and space vehicles.