A method of measuring the mass concentration of lubricating oil in a refrigerant-oil mixture in a... more A method of measuring the mass concentration of lubricating oil in a refrigerant-oil mixture in a liquid line within a refrigeration system is described. It is suitable for use where the oil and refrigerant are fully miscible in the liquid phase, e.g. for mineral oil and R12. The technique involves taking a small liquid sample, measuring its volume, venting the refrigerant back into the system and weighing the residual oil. Many measurements can be made, with negligible loss of refrigerant from the system. An application of the method to a split circuit bypass type compressor load stand is also described. Mesure de la perte faible de la concentration d'huile d'un m61ange frigorig6ne/huile dans une conduite de liquide On d~crit une mkthode de mesure de la concentration massique de I'huile de lubrification d'un m~lange frigorig~ne/huile dans une conduite de liquide, h l'int&ieur d'un systkme frigorifique. On peut utiliser cette m~thode lorsque I'huile et le frigorig~ne sont complktement miscibles en phase liquide comme l'huile rain&ale et le R12 par exemple. Ia technique consiste gt prendre un petit ~chantillon de liquide, fi mesurer son volume, h transf&er le frigorigOne dans le syst~me et d peser l'huile rksiduelle. On peut effectuer beaucoup de mesures avec une perte n~gligeable de frigorigOne dt partir du systkme. On d~crit ~galement, pour l'application de la mkthode, le montage d'un compresseur dans le circuit avec by-pass.
The Stirling cycle engine is gaining increasing attention in the current energy market as a clean... more The Stirling cycle engine is gaining increasing attention in the current energy market as a clean, quiet and versatile prime mover for use in such situations as solar thermal generation, micro cogeneration and other micro distributed generation situations. A theoretical Stirling cycle engine model is developed. Using a theoretical decoupled engine configuration in which working space swept volume, volume variation, phase angle and dead space ratio are controlled via a black-box electronic controller, a model is developed that is to be used as a tool for analysis of the ideal Stirling cycle engine and the limits on its real world realisation. The theoretical configuration approximates the five-space configuration common in Stirling cycle analysis. It comprises two working spaces and three heat exchangers: hot side, cold side and the regenerator between. The kinematic crank mechanism is replaced with an electronically controlled motor/generator system, with one motor/generator controlling each of the working pistons. Use of stop valves permits flow and non-flow processes inherent in the ideal cycle to be realised. The engine configuration considered here is not intended as a viable prime mover but rather a tool for study of the limitations of the cycle.
A new type of virtual system, named a flow constraint system (FCS), is proposed to facilitate, cl... more 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 authors on conceptual devices for exergy analysis and builds on this and the work of other authors relating to exergy and exergoeconomic analysis, especially using matrix methods. A bond graph type of diagram is described as an alternative to the usual Grassmann diagram. A numerical illustration is given in a separate paper -Part II.
The European Union has made a commitment to promoting sustainable mobility through advanced trans... more The European Union has made a commitment to promoting sustainable mobility through advanced transport logistics. One of the principal areas yet to be addressed is that of the potential barriers to advanced transport logistics and the attitudes of industry to this advancement.
In this paper I present some of my thoughts and experiences relating to 'applied thermodynamics' ... more In this paper I present some of my thoughts and experiences relating to 'applied thermodynamics' over my career so far.
This Inaugural Lecture consists of some of my rather mechanical, being an engineer, reflections o... more This Inaugural Lecture consists of some of my rather mechanical, being an engineer, reflections on symmetry in diverse areas such as art, science, engineering, mathematics, etc. I explain what symmetry is to me, giving examples with lots of images and mentioning or at least barely referencing art, science, architecture, engineering, heritage, cosmology, bicycles, flight, invention, ingenuity, history, wallpaper, mathematics, typography,
This paper describes findings from analysis and simulation in relation to the possible benefits o... more This paper describes findings from analysis and simulation in relation to the possible benefits of applying refrigeration based intercooling to the engine of a modern passenger car or haulage vehicle. Initial theoretical analysis showed that, depending on the engine specifications and the boost pressure level of the turbo/supercharger, the power improvement could range from 15-30% and there would be a similar improvement in torque. This meant a smaller engine could be used to do the work of a larger engine. The power required to run the refrigeration system, the space required and the charge air pressure drop due to its passage through the system were all within what were believed to be acceptable limits. It was envisaged that the proposed system would have a secondary function as an air conditioning unit to save space. An engine simulation software package, Ricardo WAVE, was used to simulate the engines that had been investigated in the theoretical calculations. The engines were simulated with and without refrigerated intercooling. There was good correlation between the simulation results and the simpler theoretical analyses. Slight gains in efficiency were predicted, but the main potential benefits were increased power and torque output.
The purpose of the work was to critically re-examine and investigate the evaluation of refrigeran... more The purpose of the work was to critically re-examine and investigate the evaluation of refrigerant compressors and to determine and discriminate between the factors which influence their characteristics. The objectives also included the investigation of techniques by which the characteristics can be established and the suggestion of ways in which compressor performance can be described and quantified. The particular compressor
ASME 2010 4th International Conference on Energy Sustainability, Volume 2, 2010
A project has been underway at the Dublin Institute of Technology (DIT) to investigate the feasib... more A project has been underway at the Dublin Institute of Technology (DIT) to investigate the feasibility of a combined Otto and Stirling cycle power plant in which a Stirling cycle engine would serve as a bottoming cycle for a stationary Otto cycle engine. This type of combined cycle plant is considered to have good potential for industrial use. This paper describes work by DIT and collaborators to validate a computer simulation model of the combined cycle plant. In investigating the feasibility of the type of combined cycle that is proposed there are a range of practical realities to be faced and addressed. Reliable performance data for the component engines are required over a wide range of operating conditions, but there are practical difficulties in accessing such data. A simulation model is required that is sufficiently detailed to represent all important performance aspects and that is capable of being validated. Thermodynamicists currently employ a diverse range of modeling, analysis and optimization techniques for the component engines and the combined cycle. These techniques include traditional component and process simulation, exergy analysis, entropy generation minimization, exergoeconomics, finite time thermodynamics and finite dimensional optimization thermodynamics methodology (FDOT). In the context outlined, the purpose of the present paper is to come up with a practical validation of a practical computer simulation model of the proposed combined Otto and Stirling Cycle Power Plant.
A method of measuring the mass concentration of lubricating oil in a refrigerant-oil mixture in a... more A method of measuring the mass concentration of lubricating oil in a refrigerant-oil mixture in a liquid line within a refrigeration system is described. It is suitable for use where the oil and refrigerant are fully miscible in the liquid phase, e.g. for mineral oil and R12. The technique involves taking a small liquid sample, measuring its volume, venting the refrigerant back into the system and weighing the residual oil. Many measurements can be made, with negligible loss of refrigerant from the system. An application of the method to a split circuit bypass type compressor load stand is also described. Mesure de la perte faible de la concentration d'huile d'un m61ange frigorig6ne/huile dans une conduite de liquide On d~crit une mkthode de mesure de la concentration massique de I'huile de lubrification d'un m~lange frigorig~ne/huile dans une conduite de liquide, h l'int&ieur d'un systkme frigorifique. On peut utiliser cette m~thode lorsque I'huile et le frigorig~ne sont complktement miscibles en phase liquide comme l'huile rain&ale et le R12 par exemple. Ia technique consiste gt prendre un petit ~chantillon de liquide, fi mesurer son volume, h transf&er le frigorigOne dans le syst~me et d peser l'huile rksiduelle. On peut effectuer beaucoup de mesures avec une perte n~gligeable de frigorigOne dt partir du systkme. On d~crit ~galement, pour l'application de la mkthode, le montage d'un compresseur dans le circuit avec by-pass.
The Stirling cycle engine is gaining increasing attention in the current energy market as a clean... more The Stirling cycle engine is gaining increasing attention in the current energy market as a clean, quiet and versatile prime mover for use in such situations as solar thermal generation, micro cogeneration and other micro distributed generation situations. A theoretical Stirling cycle engine model is developed. Using a theoretical decoupled engine configuration in which working space swept volume, volume variation, phase angle and dead space ratio are controlled via a black-box electronic controller, a model is developed that is to be used as a tool for analysis of the ideal Stirling cycle engine and the limits on its real world realisation. The theoretical configuration approximates the five-space configuration common in Stirling cycle analysis. It comprises two working spaces and three heat exchangers: hot side, cold side and the regenerator between. The kinematic crank mechanism is replaced with an electronically controlled motor/generator system, with one motor/generator controlling each of the working pistons. Use of stop valves permits flow and non-flow processes inherent in the ideal cycle to be realised. The engine configuration considered here is not intended as a viable prime mover but rather a tool for study of the limitations of the cycle.
A new type of virtual system, named a flow constraint system (FCS), is proposed to facilitate, cl... more 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 authors on conceptual devices for exergy analysis and builds on this and the work of other authors relating to exergy and exergoeconomic analysis, especially using matrix methods. A bond graph type of diagram is described as an alternative to the usual Grassmann diagram. A numerical illustration is given in a separate paper -Part II.
The European Union has made a commitment to promoting sustainable mobility through advanced trans... more The European Union has made a commitment to promoting sustainable mobility through advanced transport logistics. One of the principal areas yet to be addressed is that of the potential barriers to advanced transport logistics and the attitudes of industry to this advancement.
In this paper I present some of my thoughts and experiences relating to 'applied thermodynamics' ... more In this paper I present some of my thoughts and experiences relating to 'applied thermodynamics' over my career so far.
This Inaugural Lecture consists of some of my rather mechanical, being an engineer, reflections o... more This Inaugural Lecture consists of some of my rather mechanical, being an engineer, reflections on symmetry in diverse areas such as art, science, engineering, mathematics, etc. I explain what symmetry is to me, giving examples with lots of images and mentioning or at least barely referencing art, science, architecture, engineering, heritage, cosmology, bicycles, flight, invention, ingenuity, history, wallpaper, mathematics, typography,
This paper describes findings from analysis and simulation in relation to the possible benefits o... more This paper describes findings from analysis and simulation in relation to the possible benefits of applying refrigeration based intercooling to the engine of a modern passenger car or haulage vehicle. Initial theoretical analysis showed that, depending on the engine specifications and the boost pressure level of the turbo/supercharger, the power improvement could range from 15-30% and there would be a similar improvement in torque. This meant a smaller engine could be used to do the work of a larger engine. The power required to run the refrigeration system, the space required and the charge air pressure drop due to its passage through the system were all within what were believed to be acceptable limits. It was envisaged that the proposed system would have a secondary function as an air conditioning unit to save space. An engine simulation software package, Ricardo WAVE, was used to simulate the engines that had been investigated in the theoretical calculations. The engines were simulated with and without refrigerated intercooling. There was good correlation between the simulation results and the simpler theoretical analyses. Slight gains in efficiency were predicted, but the main potential benefits were increased power and torque output.
The purpose of the work was to critically re-examine and investigate the evaluation of refrigeran... more The purpose of the work was to critically re-examine and investigate the evaluation of refrigerant compressors and to determine and discriminate between the factors which influence their characteristics. The objectives also included the investigation of techniques by which the characteristics can be established and the suggestion of ways in which compressor performance can be described and quantified. The particular compressor
ASME 2010 4th International Conference on Energy Sustainability, Volume 2, 2010
A project has been underway at the Dublin Institute of Technology (DIT) to investigate the feasib... more A project has been underway at the Dublin Institute of Technology (DIT) to investigate the feasibility of a combined Otto and Stirling cycle power plant in which a Stirling cycle engine would serve as a bottoming cycle for a stationary Otto cycle engine. This type of combined cycle plant is considered to have good potential for industrial use. This paper describes work by DIT and collaborators to validate a computer simulation model of the combined cycle plant. In investigating the feasibility of the type of combined cycle that is proposed there are a range of practical realities to be faced and addressed. Reliable performance data for the component engines are required over a wide range of operating conditions, but there are practical difficulties in accessing such data. A simulation model is required that is sufficiently detailed to represent all important performance aspects and that is capable of being validated. Thermodynamicists currently employ a diverse range of modeling, analysis and optimization techniques for the component engines and the combined cycle. These techniques include traditional component and process simulation, exergy analysis, entropy generation minimization, exergoeconomics, finite time thermodynamics and finite dimensional optimization thermodynamics methodology (FDOT). In the context outlined, the purpose of the present paper is to come up with a practical validation of a practical computer simulation model of the proposed combined Otto and Stirling Cycle Power Plant.
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Papers by Jim A McGovern