15. Generating Heat: Thermochemistry
[SB&VW-14.1-14.6]
Until now, we have specified the heat given to the devices analyzed,
and not concerned ourselves with how this heat might be produced. In
this section, we examine the issue of how we obtain the heat needed
for work production. For the most part, this is from converting
chemical energy into heat, so the discussion will be on reacting
mixtures of gas which are involved in chemical combustion processes.
The topic addressed is ``thermochemistry,'' which is the combining
of thermodynamics with chemistry to predict such items as how much
heat is released from a chemical reaction. This is the ``Q'' or
``q'' that we have used in the cycle analysis. The principal
components of the approach are use of a chemical balance plus the
steady flow energy equation (SFEE) which equates the sum of shaft
work (from) and heat transfer (to) a control volume to the
difference in control volume inlet and exit enthalpy fluxes.
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