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Efficiency, Loss...is there a more specific term?

  1. Apr 3, 2017 #1
    Suppose I heat a room directly by lighting a fire in the room, let's say it is a butane gas fire and it takes n BTU to raise the temperature by 10°C.

    Now, suppose I don't like the smell of burning gas fumes and decide instead to move the same gas fire outside and boil water to generate steam to run a generator to produce electricity to power an electric heater in the same room and it takes 3n BTU to raise the temperature by 10°C.

    Is there a technical term to descibe the 3 x BTU difference between direct heat and indirect heat in the above?
  2. jcsd
  3. Apr 3, 2017 #2


    Staff: Mentor


    The word in your title; efficiency. I'm not sure what other word you are searching for.
  4. Apr 3, 2017 #3


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    I think it would be best to call it something like the "relative efficiency" because the original butane fire isn't going to be 100% efficient.
  5. Apr 3, 2017 #4


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    Staff: Mentor

    I don't see a problem with using "efficiency" as long as you describe clearly what you are talking about. As said, it isn't necessarily straightforward. For this situation, there is a potential difference between total and sensible energy output (lower vs higher heating value), that may still make the efficiency of the fire in the room less than 100%. And if the system is properly vented so as not to violate code/kill anyone, the ventilation should be factored into the efficiency as well.
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