The fundamentals of thermodynamics and thermodynamic analysis are provided, as they are central to the contents of the book. The centrality of thermodynamics can be seen by noting that it constitutes the study of the concepts and laws describing energy and its conversion in processes and systems. The means by which thermodynamics permits the behavior, performance and efficiency of energy systems to be described, particularly via energy and exergy analyses, is described at length. Details on aspects of thermodynamics most relevant to energy and exergy analyses are presented and illustrated, along with descriptions of energy and exergy analyses themselves. Thermodynamic balances and basic quantities in them are described, including the exergy of matter, heat, work and electricity. The reference environment used in exergy analysis is described and models for it (e.g., natural-environment-subsystem, reference-substance, equilibrium and constrained-equilibrium, and process-dependent models) are detailed. Various energy and exergy efficiencies are defined and properties for energy and exergy analyses are provided. The implications are explained of energy and exergy analyses, particularly on research and development. A step-by-step procedure is given for energy and exergy analyses, and a detailed example is given to illustrate how the analyses are applied. Finally, exergy values for typical commodities encountered in cogeneration and district energy (e.g., electricity, work, heated and cooled substances) are provided, and extensions are explained of exergy methods beyond thermodynamics to areas such as economics and environmental studies. The coverage in this chapter is kept general where possible, although points relevant to cogeneration and/or district energy are raised as appropriate.

Chapter Contents:

• Overview
• 2.1 Introduction
• 2.2 Energy analysis
• 2.3 Exergy analysis
• 2.3.1 The exergy method of analysis
• 2.3.2 Improving efficiency with exergy analysis: illustration for electricity generation
• 2.3.3 Illustration of exergy analysis for electrical resistance space heating
• 2.3.4 Illustration of exergy analysis for thermal energy storage
• 2.4 Thermodynamic nomenclature and terminology
• 2.5 Thermodynamic balance equations and basic quantities
• 2.5.1 Balance equations
• 2.5.1.1 General balance equations
• 2.5.1.2 Thermodynamic balance equations
• 2.5.2 Quantities in balance equations
• 2.5.2.1 Exergy of a flowing stream of matter
• 2.5.2.2 Exergy of heat
• 2.5.2.3 Exergy of work and electricity
• 2.5.2.4 Exergy consumption
• 2.6 The reference environment
• 2.6.1 Natural-environment-subsystem models
• 2.6.2 Reference-substance models
• 2.6.3 Equilibrium and constrained-equilibrium models
• 2.6.4 Process-dependent models
• 2.7 Efficiencies
• 2.7.1 Conventional energy and exergy efficiencies
• 2.7.2 Alternative efficiencies
• 2.8 Properties for energy and exergy analyses
• 2.9 Implications of energy and exergy analyses on related research and development
• 2.9.1 Correlating energy and exergy analyses with allocations of research efforts
• 2.9.2 Measures to reduce exergy losses
• 2.10 Steps for energy and exergy analyses
• 2.11 Illustrative example
• 2.11.1 Description and subdivision for analysis of system considered
• 2.11.1.1 Description of overall PFBC power plant
• 2.11.1.2 Description of PFBC subsystem
• 2.11.2 Performance of conventional mass and energy balances
• 2.11.3 Selection of reference-environment model
• 2.11.4 Evaluation of energy and exergy flow rates
• 2.11.4.1 Water flows
• 2.11.4.2 Air flows
• 2.11.4.3 Other gas flows
• 2.11.4.4 Solid flows
• 2.11.4.5 Miscellaneous heat losses
• 2.11.5 Performance of exergy balances and determination of exergy consumptions
• 2.11.6 Selection and evaluation of efficiencies
• 2.11.7 Interpretation of results
• 2.12 Exergy values for typical commodities encountered in cogeneration and district energy
• 2.12.1 Exergy values for thermal quantities
• 2.12.2 Exergy values for other thermodynamic quantities
• 2.13 Extensions of exergy methods
• 2.14 Closure

Inspec keywords: cogeneration; exergy

Other keywords: cogeneration; environmental studies; process-dependent model; constrained-equilibrium model; thermodynamic analysis; energy efficiency; exergy analysis; natural-environment-subsystem; reference-substance model; district energy; economics; thermodynamic balances

Subjects: Heat and thermodynamic processes (mechanical engineering); Thermal power stations and plants; Power and plant engineering (mechanical engineering)