REFLECTIONS ON THE PEDAGOGIC MOTIVE POWER OF UNCONVENTIONAL THERMODYNAMIC CYCLES

Pedagogic niceties in the treatment of unconventional thermodynamic cy cles, especially those involving (negatively sloping) diagonal linear transitions in a PIV state diagram and/or those implying supposedly su perefficient heat-engine operation, are discussed as a means of stimul ating student interest and comprehension, as well as promoting fresh i nsights, correcting erroneous notions, and provoking further enquiry. In particular, a novel (ostensibly all-adiabatic) engine using two ide al gases of mutually differing atomicities as working substance is ana lyzed qualitatively and quantitatively. Emphasis is placed on the cruc ial role of the second law, of thermodynamics in a determination of he at-engine operation. (C) 1996 American Association of Physics Teachers .