Talk:Sigma heat

Total heat

What is the connection of this subject to "total heat" which redirects to Enthalpy? ChildofMidnight (talk) 19:25, 22 September 2009 (UTC)

Total heat and sigma heat both refer to the energy of humid air above a base temperature. Total heat is a bit ambiguous, however, as its details are sometimes identical to sigma heat and sometimes identical to specific enthalpy. The difference is as follows. Sigma heat excludes any energy the water vapor may have below its condensation point, because it assumes that any such liquid will be drained off during any real-life cooling process. In contrast, enthalpy does include this energy, which is a little silly of course, because in practice there is no reason to chill the the entire system of humid air (moisture too) to sub-freezing temperatures. The advantage of enthalpy however is that it is a well-known concept beyond the mining engineering world. Sometimes engineers use the term "true total heat" to be clear that they are speaking of specific enthalpy and not sigma heat. Riick (talk) 00:16, 15 September 2010 (UTC)