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Full-Text Articles in Mechanical Engineering
Available Work Rate Of A Reversible System Bounded By Constant Thermal Resistances Linked To Isothermal Reservoirs, Jim Mcgovern
Available Work Rate Of A Reversible System Bounded By Constant Thermal Resistances Linked To Isothermal Reservoirs, Jim Mcgovern
Conference Papers
Exergy analysis is based on the concept of an idealized, all-enclosing reference environment that has infinite heat capacity and thermal conductivity, and is in equilibrium. The actual surroundings of a real plant such as a heat engine, a heat pump or a refrigerator may differ significantly from the ideal. First law performance parameters and second law rational efficiency are examined. The concepts of finite time thermodynamics are applied in an attempt to refine the concept of T0, the environmental reference temperature, thereby making exergy analysis more reflective of reality.
Some Experiences, Thoughts, Ideas And Open Questions Relating To Applied Thermodynamics, Jim Mcgovern
Some Experiences, Thoughts, Ideas And Open Questions Relating To Applied Thermodynamics, Jim Mcgovern
Articles
In this paper I present some of my thoughts and experiences relating to 'applied thermodynamics' over my career so far. I explain my interest in thermodynamics, describe some topics I have worked on, point out some questions that appear still to be open and outline some ideas for work that could be done. I describe how I was inspired to pursue the area of applied thermodynamics, with reference to a glass, opposed-piston internal combustion engine. I put my heat pump research in the late 1970s briefly into today's context. Some of my research has been in relation to compressors, which …
Termes De Signes Positif Et Négatif En Analyses Exergétiques Des Flux De Chaleur, Jim Mcgovern, Pierre Le Goff
Termes De Signes Positif Et Négatif En Analyses Exergétiques Des Flux De Chaleur, Jim Mcgovern, Pierre Le Goff
Articles
In various technical plants there are heat transfer rates at temperatures above that of the environment and other simultaneous heat transfer rates at temperatures below the temperature of the environment. This is the case in cryogenic industrial processes where a cooling effect is produced from a heat source. This is also the case for all absorption refrigeration plants or absorption plants that provide refrigeration and heat pumping, notably for air-conditioning of buildings. In these cases exergetic analysis leads to equations in which some terms are positive and others are negative. This can pose problems in the definition of exergetic, or …
A Virtual-System Concept For Exergy Analysis Of Flow Network Plant; Part I: Principles, Jim Mcgovern, Francis O'Toole
A Virtual-System Concept For Exergy Analysis Of Flow Network Plant; Part I: Principles, Jim Mcgovern, Francis O'Toole
Conference Papers
A new type of virtual system, named a flow constraint system (FCS), is proposed to facilitate, clarify, and simplify exergy analyses of plant that involve material flow networks. The need for the virtual system is outlined and the concept is demonstrated by applying it to a CHP steam cycle. The FCS concept allows the physical constraints on the exergy interactions associated with flow streams to be taken into account fully. It also simplifies the treatment of bifurcations in material flows and considerably reduces the need for absolute exergy evaluations. The new concept follows from the work already published by the …
A Virtual-System Concept For Exergy Analysis Of Flow Network Plant; Part Ii: Exergetic And Exergonomic Analysis Illustration, Jim Mcgovern, Francis O'Toole
A Virtual-System Concept For Exergy Analysis Of Flow Network Plant; Part Ii: Exergetic And Exergonomic Analysis Illustration, Jim Mcgovern, Francis O'Toole
Conference Papers
This paper is a continuation of Part I — Principles, to which it refers extensively. The virtual system concept and the methodology introduced in Part I are illustrated by means of a numerical example. This is an exergetic and exergoeconomic analysis of the CHP steam plant that was described in Part I without operating values and parameters. Matrix methods developed by Valero et al. (1986) are adapted to the new concept. It is shown that these methods are made simpler and less subjective. Bond-graph-type diagrams for exergetic and economic costs are presented.