Radiant Heating (infrared heating) And Induction Heating – EEE

Infrared Heating or Radiant Heating Working Principle

  • In the ordinary resistance furnaces, the heat (radiant heat) is transferred from heating elements to the charge partly by radiation and partly by convection, the latter is predominating at low and medium temperatures. But, in this form of heating which is suitable for low and medium temperature heating purely radiant heating (radiant heat) or infrared heating is used.
  • In this method of heating (infrared heating), elements consist of tungsten filament lamps together with reflectors to direct the whole of the heat (radiant heat) emitted on to the charge.
  • The lamps are operated at 2,300 0c instead of 3,000 0c giving a greater proportion of infrared radiations and longer life.
  • The reflectors are plated with rhodium. The lamps employed are usually of a rating between 250 and 1,000 watts operating at 115 volts.
  • The operation at low voltage results in a robust filament. With this arrangement charge temperature between 200 0c and 300 0c can be obtained.
  • Heat emission intensities up to 7,000 watts/ square meter of the chamber surface can be obtained. These are much higher than those obtained with ordinary resistance furnaces (1,500 watts/m2).
  • In radiant heating (infrared heating), heat absorption remains practically constant whatever be the charge temperature whereas it falls rapidly as the temperature of charge rises in the ordinary resistance furnace.
  • Paint drying is a common application of this method. It is also used for drying foundry molds, low-temperature heating of plastics, and for various dehydration and other processes.

Induction Heating Working Principle

induction heating radiant heating electrical engineering
  • The induction heating works on the principle of transformer action.
  • The transformer working principle is based on Faraday’s law of electromagnetic induction. This transfers the electrical energy from the primary side to the secondary side (circuit) of the transformer.
  • The working principle of induction furnaces is similar to the eddy current loss in the transformer.
  • This loss is dissipated in the form of heat in the transformer cores. If such a loss in the form of heat is utilized in the heating of materials, then it will be useful to heat up the charge.
  • When an alternating current flows in a conductor, it produces a reversing magnetic field.
  • If any coil is placed in this reversing magnetic field, an emf will induce in it. Similar to the emf induced in the secondary of a transformer.
  • This transfer of electric energy from the primary winding to the secondary winding by electromagnetic induction is utilized to form the heat.
  • The heat developed in the charge mainly depends on the following factors :
    1. The power is drawn by the charge.
    2. Supply voltage and current.
    3. The resistance of the charge.
  • The power depends upon the voltage, power frequency and the resistance of the charge, power drawn is equal to v2/R .
  • Therefore, to develop a sufficient amount of heal for one liter of the charge,
    1. The resistance of the charge must be low which is possible only with metal.
    2. Voltage must be higher which is obtained by employing higher flux and higher frequency.

Topics of Electric Heating

  1. electric heating: advantages & types of electric heating
  2. Methods | Types Of Electric Heating In Electrical Engineering | Applications
  3. Resistance Ovens & Furnaces: General Construction & Heating Chambers
  4. Direct And Indirect Resistance Heating
  5. Resistance oven : Efficiency and losses – EEE
  6. Radiant Heating (infrared heating) And Induction Heating – EEE
  7. Core Type Furnace – EEE
  8. Indirect Induction Oven | Types Of Core Type Induction Furnaces – EEE
  9. Coreless Furnace & Advantages Of Coreless Furnace
  10. Ajax Wyatt Furnace Principle – Advantages – Drawbacks – Applications
  11. High Frequency Eddy Current Heating principle – Advantages – Disadvantages – Applications
  12. Dielectric Heating – principle – advantages – applications
  13. What is Electric Arc furnace & Methods of striking the arc
  14. Direct Arc Furnace & Indirect Arc Furnace | Electrical engineering
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