Exergy representations in thermodynamics

Abstract

Papers presented to the 11th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 20-23 July 2015.The paper reviews various representations of exergy and exergy losses in energy systems going from simple heat exchanger (heat transfer, dissipation and embedded exergy) to the exergy of full energy systems from fossil or non fossil resources (including the diffusion exergy). The systems shown include shell in tube heat exchangers, thermal power cycles, cogeneration, heat pump direct heating systems and cryogenic systems. The representations include simple gravitational analogies to extended exergy pinch diagrams and finally to the exergy bowl with the dead states corresponding, for example, to different oxidation products. The transformation from hydrocarbons to CO2 and H20 is shown in particular, highlighting the diffusion exergy of CO2, which is important when dealing with concepts of CO2 capture.