What is radiant heating in the context of boilers?

What is radiant heating in the context of boilers?

Right Answer is:

Heating process carried out using radiation effect

SOLUTION

Depending upon the way heat is transferred, super-heaters are classified into three types:

  1. Radiant superheaters
  2. Convective superheaters
  3. Combined radiative and convective superheaters

Radiant Superheater

  • Radiant superheaters receive energy primarily from thermal radiation from the furnace with little energy from convective heat transfer.
  • Radiant superheaters are located at the furnace exit or turning section.
  • The radiant superheater absorbs more enthalpy at partial loads when compared to the convective type.
  • At lower loads, the flow distribution inside the superheater tubes is less uniform. The radiant superheater outlet temperature decreases with increasing boiler output.
  • At higher loads the mass flow rate of the combustion gas is high, because of the increased amount of fuel and air for combustion.
  • The convective heat transfer coefficient increases both inside and outside the tubes. Thus the steam re- receives more heat transfer per unit mass flow rate, and its temperature increases with load.
  • The surface area required to transfer a given amount of energy will be lower due to the higher log mean temperature difference and higher heat transfer coefficient.
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