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Name: Akash P.
Status: Student
Age: 18
Location: N/A
Country: N/A
Date: November 2002


Question:
I walked into an appliance store yesterday and I saw energy / efficiency ratings for gas stoves and microwaves. My question is where does the wasted energy for a gas stove go? Assuming 40% efficiency, where does the 60% go in a gas stove. I presume that some of it would become infrared radiation, some pushes against the atmosphere. How can the wasted energy be accounted for and what equations can one use for that. ie. energy lost in IR, energy lost to surrounding air, energy lost to stove.



Replies:
It is not clear how the manufacturer is defining "efficiency", or what the configuration of the stove is. The latter has a big effect. In a gas stove (I am not sure if you mean a furnace for heating a home or a cooking stove) most of the heat loss occurs because hot CO2 and H2O go "up the stack" that is there is not an efficient heat exchanger to capture all of the heat energy. The infrared radiation produced is not really lost because it heats the air surrounding the stove. I do not know of any simple equations to describe in any detail what is going on.

Vince Calder



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