Corrected energy balance in CompressorBase

git-svn-id: https://thermopower.svn.sourceforge.net/svnroot/thermopower/trunk@195 80daafeb-7430-0410-91d5-8b30b0bbd841
Corrected flow-dependent heat transfer correlations

git-svn-id: https://thermopower.svn.sourceforge.net/svnroot/thermopower/trunk@196 80daafeb-7430-0410-91d5-8b30b0bbd841