October 23, 2021, 05:07:31 PM
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Topic: Energy density & heat released on combustion - need some clarification  (Read 5197 times)

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Offline Joseph

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Hi,

I am analyzing the energy of different fuels. I have several fuels and for each fuel I have the energy density and the energy that is released from heat of combustion. The way I understand energy density is the energy that a substance has per unit so ethanol for example has an energy density of 28000kJ/kg which means for every kilogram, there is 28000kJ of energy. Is my understanding of this correct?

Anyway, the heat energy released from combustion is always more than the energy density. Why is this so? I would have thought it would have been the other way around.

Thanks for your replies

Offline Astatine

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Yes, energy density is the amount of energy released when a unit mass of the fuel is burnt.
28000kJ/kg implies that 28000kJ of energy is released when 1 kg of it is burnt.

The heat energy released depends on the mass of fuel burnt. If the mass of the fuel burnt is 0.01kg, the value is lower than the energy density.

Offline Joseph

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Thanks for confirming that for me  :)

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