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Articles 61 - 73 of 73
Full-Text Articles in Energy Systems
Thermal Control Of An Occupied Room: Investigating The Use Of Carbon Dioxide Concentration As An Auxiliary Control Variable, Kevin O'Connell, Aidan O'Dwyer
Thermal Control Of An Occupied Room: Investigating The Use Of Carbon Dioxide Concentration As An Auxiliary Control Variable, Kevin O'Connell, Aidan O'Dwyer
Conference papers
This paper details the theoretical and experimental work done in the examination of the relationship between human generated carbon dioxide concentration and temperature rise in an occupied room. Generation of carbon dioxide by humans is linked to metabolic rate and heat generation. Therefore, carbon dioxide concentration may be used as an indicator of occupancy in a room. Typically, a heating control system will react slowly to changes in room occupancy if temperature is used as the process variable. The aim of the work was to establish if carbon dioxide concentration in the space could be used as an auxiliary control …
Solar Energy Conversion Through Seaweed Photosynthesis With Combustion In A Zero-Emission Power Plant, Evgeny Yantovski, Jim Mcgovern
Solar Energy Conversion Through Seaweed Photosynthesis With Combustion In A Zero-Emission Power Plant, Evgeny Yantovski, Jim Mcgovern
Other resources
A proposed ‘closed cycle’ power plant scheme, referred to as SOFT (Solar Oxygen Fuel Turbine), is described. The scheme involves the cultivation of macroalgae in a pond, combustion of their organic matter in a fluidised bed boiler that generates steam for a Rankine cycle steam power plant and the return of the combustion products to the pond to feed the algae. Oxygen, equivalent to that used for combustion, is re-released to the atmosphere by photosynthesis, while the carbon dioxide that is produced by combustion is absorbed by photosynthesis and thereby recycled. It is proposed that the seaweed Ulva, which is …
Reducing Energy Costs By Optimizing Controller Tuning, Aidan O'Dwyer
Reducing Energy Costs By Optimizing Controller Tuning, Aidan O'Dwyer
Conference papers
The proportional integral derivative (PID) controller is the most dominant form of automatic controller in industrial use today. With this technique, it is necessary to adjust the controller parameters according to the nature of the process. This tailoring of controller to process is known as controller tuning. Controller tuning is easily and effectively performed using tuning rules (i.e. formulae for controller tuning, based on process information). Such tuning rules allow the easy set up of controllers to achieve optimum performance at commissioning. Importantly, they allow ease of re-commissioning if the characteristics of the process change. The paper outlines the results …
Indirect Evaporative Cooling Potential In Air-Water Systems In Temperate Climates, Ben Costelloe, Donal Finn
Indirect Evaporative Cooling Potential In Air-Water Systems In Temperate Climates, Ben Costelloe, Donal Finn
Articles
Recent developments have prompted a review of evaporative cooling technology as an effective means of cooling modern deep plan buildings. Prominent among these developments is the success of high temperature sensible cooling systems, particularly, chilled ceilings, which require a supply of cooling water at 14–18 °C. Crucial to the success of evaporative cooling technology, as a significant means of cooling in modern applications, is the ability to generate cooling water, in an indirect circuit, at a temperature which closely approaches the ambient adiabatic saturation temperature (AST) or wet bulb temperature (WBT). Recent experimental research has demonstrated that it is technically …
The Role Of Computer Simulation In The Context Of Zero-Emission Power Plants, Jim Mcgovern
The Role Of Computer Simulation In The Context Of Zero-Emission Power Plants, Jim Mcgovern
Other resources
The role of computer simulation in the context of zero-emission power plants is outlined. The use of computer simulation models to simulate zero-emission power plants in fine detail is strongly recommended.
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 …
Chp And Energy Conservation, Jim Mcgovern
Chp And Energy Conservation, Jim Mcgovern
Articles
The principles of the use of 'combined heat and power' (CHP) for the achievement of fuel energy conservation, minimisation of environmental impact and economic advantage are explained. A distinction is made between the two types of outputs: heat and work. It is argued that an efficiency value that is defined as the sum of the heat and work outputs divided by the energy of the fuel used is not very meaningful. An alternative, rational, efficiency is explained. It is concluded that CHP is an option to be considered where both heating and power are required, but is not a general …
Exergetic Cost Analysis Of A Mechanical Exergy Recycle, Jim Mcgovern
Exergetic Cost Analysis Of A Mechanical Exergy Recycle, Jim Mcgovern
Conference Papers
A mechanical plant that involves an exergy recycle is presented for analysis. It consists of gearboxes and a fluid coupling. There is one input of shaft power to the plant and there are three separate outputs of shaft power. An exergetic cost analysis approach is outlined and applied to the plant.
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.
A Heat Pump Assisted Shower, Jim Mcgovern
A Heat Pump Assisted Shower, Jim Mcgovern
Articles
An energy-efficient water-heating system for a shower is proposed consisting of a low-powered heat pump, a storage tank and an instantaneous heater which, it is felt, may yield a favourable overall cost, in addition to reducing the primary energy consumption. Some preliminary work has been carried out in exploring this concept. It was considered at the outset that an overall coefficient of performance (COP) of 2 should be readily achieved. Values close to this have been realised with the first experimental prototype.
Heat Pump Evaluation And Design For The Irish Climate, Jim Mcgovern
Heat Pump Evaluation And Design For The Irish Climate, Jim Mcgovern
Other resources
The work of this thesis concerns the application of heat pumps to domestic space heating in Ireland. Only small air-source electric-powered vapour compression plants using fluorocarbon refrigerants are considered. Tests have been carried out on an air-to-air heat pump unit with a rated heat output of 3 kW. The performance characteristics of each of the system components have been determined from the test results. Computer programs have been written to calculate performance figures for theoretical heat pump cycles and refrigerants 12, 22 and 502 have been compared with one another on the basis of theoretical performance. A computer program has …
Heat Pump Research Programme At University College Dublin (1976), Seamus Timoney, Jim Mcgovern
Heat Pump Research Programme At University College Dublin (1976), Seamus Timoney, Jim Mcgovern
Conference Papers
This paper describes heat pump research at University College Dublin in 1976 relating to an air-to-air heat pump. The plant under test and its instrumentation are described and some measured performance data are presented. A heat pump simulation program is described. A theoretical comparison of refrigerants 12, 22 and 502 is presented with graphs of performance parameters as a function of operating conditions.