rajeshkharcherajeshkharche Registered Users Posts: 1
edited January 2018 in Energy Use & Conservation #1

Hi everyone,

What is desuperheater ? how it is useful in solar system?

Anybody knows about this?


Rajesh Kharche


  • mcgivormcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    A desuperheater is a heat exchanger used to scavenge wasted energy in the exhaust of superheated steam boilers. The only application I can think of  in solar energy, would be in a solar thermal power plants, usually large scale and complex, not for DIY applications.
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  • LucManLucMan Solar Expert Posts: 223 ✭✭✭
    A desuperheater can also be used in the hot gas discharge line of an airconditioning or refrigeration system to heat water for domestic or process use.
  • Dave AngeliniDave Angelini Solar Expert Posts: 6,090 ✭✭✭✭✭
    Or as Honda planned ( a bit different)  with their home generators. The CoGen was tested in England but never made it over the pond.

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  • Sol4rSol4r Registered Users Posts: 7 ✭✭
    Or as Honda planned ( a bit different)  with their home generators. The CoGen was tested in England but never made it over the pond.

    Will check that out
  • Solar2Solar2 Registered Users Posts: 30 ✭✭
    My apologies for reopening this old thread but superheat is misunderstood on this web site.
    Superheat is the heat supplied a working fluid such as steam or freon that raises its temperature above its condensing point.
    It is usually specified in degrees which is a misnomer.  It should be called super temperature. But going on.

    A steam turbine can only work on the superheat in the steam.
    When the temperature of the steam gets down to its condensing temperature it becomes wet and the turbine can no longer extract power.
    For this reason steam plants always have superheaters in their boilers.
    In fact the steam is usually returned two or three times back to the boiler for more superheat before it is exhausted to the condenser.
    This is the reason for the two or three stage turbine.

    In the case of a heat pump, the superheat in the compressor discharge is due to the in-efficiency of the compressor.
    If we could make a compressor that was 100% efficient it would have no superheat in its discharge.

    Desuperheaters used to be quite common with the old air conditioners and heat pumps.
    In this case a heat exchanger (desuperheater) was placed in the compressor discharge to produce domestic hot water.
    Any hot water produced was free since this superheat energy is normally wasted in the condenser.
    But today compressors and the freons are much more efficient resulting is less available superheat.
    Because of the reduced superheat it is less worthwhile to try to collect it.
    You can still get heat pumps with desuperheaters in them but they do not produce much hot water.

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  • jonrjonr Solar Expert Posts: 1,386 ✭✭✭✭
    On the other hand, what is often called a "desuperheater" can also act as an auxiliary condenser - where there is lots of waste heat when a heat pump is operating in cooling mode.

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