Thursday 10 March 2011

HEAT EXCHANGERS



A heat exchanger is a heat-transfer devise that is used for transfer of internal thermal energy between two or more fluids available at different temperatures. In most heat exchangers, the fluids are separated by a heat-transfer surface, and ideally they do not mix. Heat exchangers are used in the process, power, petroleum, transportation, air conditioning, refrigeration, cryogenic, heat recovery, alternate fuels, and other industries. Common examples of heat exchangers familiar to us in day-to-day use are automobile radiators, condensers, evaporators, air pre-heaters, and oil coolers.

SHELL AND TUBE HEAT EXCHANGER

In process industries, shell and tube exchangers are used in great numbers, far more than any other type of exchanger. More than 90% of heat exchangers used in industry are of the shell and tube type. The shell and tube heat exchangers are the “work horses” of industrial process heat transfer. They are the first choice because of well-established procedures for design and manufacture from a wide variety of materials, many years of satisfactory service, and availability of codes and standards for design and fabrication. They are produced in the widest variety of sizes and styles. There is virtually no limit on the operating temperature and pressure.

Classification of Shell and Tube Heat Exchangers

There are four basic considerations in choosing a mechanical arrangement that provides for efficient heat transfer between the two fluids while taking care of such practical matters as preventing leakage from one into the other.
·        Consideration for differential thermal expansion of tubes and shell.
·        Means of directing fluid through the tubes.
·        Means of controlling fluid flow through the shell.
·        Consideration for ease of maintenance and servicing.

Heat exchangers have been developed with different approaches to these four                    fundamental design factors. Three principal types of heat exchangers

·        Fixed tube-sheet exchangers
·        U-tube exchangers and
·        Floating head exchangers—satisfy these design requirements.

2 comments:

  1. Heat exchangers are used to move heat from one gaseous or liquid substance to another for the purpose of either heating or cooling a substance for another process. They are widely used in space heating, refrigeration, air conditioning, power plants, chemical plants, petrochemical plants, petroleum refineries, and natural gas processing. Thanks a lot.

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