Heat Exchangers

Heat exchangers is a device that facilitates the process of heat exchange between two or more fluids that are at different temperatures. Depending on the type of heat exchanger employed, the heat transferring process can be gas-to-gas, liquid-to-gas, or liquid-to-liquid and occur through a solid separator, which prevents mixing of the fluids, or direct fluid contact.

Heat Exchangers : Introduction

Other design characteristics, including construction materials and components, heat transfer mechanisms, and flow configurations, also help to classify and categorize the types of heat exchangers available. Finding application across a wide range of industries, a diverse selection of these heat exchanging devices are designed and manufactured for use in both heating and cooling processes.

Heat exchangers are used in many engineering applications, such as refrigeration, heating and air conditioning systems, power plants, chemical processing systems, food processing systems, automobile radiators, and waste heat recovery units. Air preheaters, economizers, evaporators, super heaters, condensers, and cooling towers used in a power plant are a few examples of heat exchangers.

Pipe tube heat exchangger
Pipe tube heat exchangger

For example, waste heat in the exhaust of an electricity-generating gas turbine can be transferred via a heat exchanger to boil water to drive a steam turbine to generate more electricity (this is the basis for Combined Cycle Gas Turbine technology).

Heat Exchanger  can be classified and categorized in several different ways based on their design characteristics. The main characteristics by which heat exchangers can be categorized include:

  • Flow configuration
  • Construction method
  • Heat transfer mechanism

The heat exchanger efficiency is defined as the ratio of the heat transferred in the actual heat exchanger to the heat that would be transferred in the ideal heat exchanger. The concept of heat exchanger efficiency provides a new way for the design and analysis of heat exchangers and heat exchanger networks.

Type of heat Exchanger

Following are the types of heat exchangers used for almost all purposes

  • Shell and tube heat exchanger.
    • Oil refining
    • Preheating
    • Oil cooling
    • Steam generation
    • Boiler blowdown heat recovery
    • Vapor recovery systems
    • Industrial paint systems
  • Tube in tube heat exchanger.
    • Distillation and refinement processes
    • Power plants
    • Refrigeration
    • HVAC
    • Chemical processing
  • Double pipe heat exchanger.
    • Industrial cooling processes
    • Small heat transfer area requirements
  • Direct and indirect heat exchanger.
  • Plate heat exchanger.
    • Cryogenic
    • Food processing
    • Chemical processing
    • Furnaces
    • Closed loop to open loop water cooling
  • Pillow plate heat exchanger.
  • Finned heat exchanger.
  • Adiabatic heat exchanger.

Heat Exchanger Characteristics

As outlined above, all heat exchangers operate under the same basic principles. However, these devices can be classified and categorized in several different ways based on their design characteristics. The main characteristics by which heat exchangers can be categorized include:

  • Flow configuration
  • Construction method
  • Heat transfer mechanism

Applications of Heat Exchangers

Heat exchangers are devices used throughout industry for both heating and cooling processes. Several variants of heat exchangers are available and find application in a wide range of industries, including:

  • ASME
  • Automotive (typically as car radiators)
  • Brewery
  • Chemical
  • Cryogenic
  • Marine
  • Power generation
  • Refrigeration heat

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