Keywords: thermodynamics, work potential, exergy, working fluids, height potential, gravitational field, hot air, humid air, solar chimney, power plants
New definition of fluid exergy in a gravitational field
This paper discusses the concept of working fluid exergy in an atmosphere stratified by a gravitational field, particularly the hot humid air in the atmosphere. A definition of exergy, different from that recently proposed by Petela (2008), is presented. Thermodynamic diagrams illustrate its elements and its technically feasible part in a transparent way. Reference papers are given for calculation of this part as technically feasible work potential of the hot humid air. This technically feasible part of the working potential can be used in the 'solar chimney'-type power plants, in cooling towers with natural circulation and in the hypothetical plants of the solar chimney type with high vortex columns instead of solar chimney.