Table of Contents
Regular Original Research Article
| Energy and Ecological Effects of the Primary Gas-Turbine Supplementing a Coal-Fired Power Plant |
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Jan T. Szargut |
1-4 |
Gas turbine fed with natural gas, introduced as a primary link of the coal-fired power plant for preheating the feed water, ensures positive energy and ecological effects. The energy effect has been expressed by means of the incremental energy efficiency, defined as the ratio of the increase of power to the chemical energy of the consumed gas. The reduction of CO2 emission has been also characterized by means of the incremental index. Formulae have been derived and numerical examples included.
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| Thermodynamics and Thermoeconomics |
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Yehia M. El-Sayed |
5-18 |
Raising the efficiency of an energy system is within the domain of thermodynamics. Raising the efficiency cost-effectively (Thermoeconomics) is a multi-disciplinary problem in which thermodynamics interfaces other disciplines of knowledge which in this particular case are design, manufacture and economics. This paper deals with a communication/optimization strategy, via the concept of costing equations, whereby the system can be analyzed and optimized for minimum cost within the domain of thermodynamics. The communication/optimization strategy is explained. The generation of costing equations is demonstrated. A gas turbine power system and seawater distillation process system are used as examples for improved design point and improved configuration. The results of their optimized design points for configurations in order of increasing complexity are displayed on cost-efficiency coordinates.
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| The Influence of the Thermophysical Fluid Properties of the New Ozone-Safe Refrigerants on Performance |
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David A. Didion |
19-35 |
The selection a working fluid as a refrigerant for the vapor compression cycle is discussed. For thermodynamic performance to be optimized particular attention must be paid to the fluid’s critical point and molar heat capacity. To achieve a reasonable balance between volumetric capacity, which implies equipment size, and coefficient of performance, which is efficiency, it is necessary to select a fluid with a critical point such that the application’s condenser will operate in a reduced temperature range of approximately 0.7 to 0.9. It is also necessary to select fluids within a rather limited range of molar heat capacity values. The specifics as to how these properties effect the cycle’s performance are presented in detail. For a better matching of the working fluid to a given application, both azeotopic and zeotropic mixtures of fluids are used. The characteristics and performance advantages and disadvantages of these mixtures are discussed.
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| Cumulative Energy and Emission Balance of Large Solar Heating Systems |
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Eric Hahne, Boris Mahler, Holger Rebholz |
37-43 |
The savings of solar energy installations are often disputed with respect to money, energy and emissions. In order to give a better insight, the various processes related to the production and operation of a large solar heating system are investigated. Material masses and operation data were obtained from a big housing project which we had planned and which is in operation; energies required and emissions were taken from literature.
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ISSN: 2146-1511
