θφ Lines of Total Heat

Abstract

I THINK that theta;φ diagram curves showing constant total heat, although often drawn by students, have never yet been published, and I venture to ask you to publish a set made more carefully than usual by one of my students, Mr. A. W. Steed. Total heat is intrinsic energy + pv, so that for steam it is what Regnault called his total heat. In the figure I have indicated the pressure, but of course the ordinate is proportional to temperature and the abscissa is entropy. Along OW the stuff is all water. Along SS the stuff is all saturated steam. The thin lines, like AB, show the stuff maintaining the same fractional dryness; for example, along AB the stuff is 0.3 of steam, 0.7 of water. Along the thicker lines, like AE, the stuff has constant total heat.