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Abstract

The fundamental issue in the energetic performance of power plants, working both as traditional fuel engines and as combined-cycle turbines (gas-steam), lies in quantifying the internal irreversibilities which are associated with the working substance operating in cycles. The purpose of several irreversible energy converter models is to find objective thermodynamic functions that determine operation modes for real thermal engines and at the same time study the trade-off between energy losses per cycle and the useful energy. As those objective functions, we focus our attention on a generalization of the so-called ecological function in terms of an ϵ parameter that depends on the particular heat transfer law used in the irreversible heat engine model. In this work, we mathematically describe the configuration space of an irreversible Curzon–Ahlborn type model. The above allows to determine the optimal relations between the model parameters so that a power plant operates in physically accessible regions, taking into account internal irreversibilities, introduced in two different ways (additively and multiplicatively). In addition, we establish the conditions that the ϵ parameter must fulfill for the energy converter to work in an optimal region between maximum power output and maximum efficiency points.

coalitions and preface xiv S N L xiv policy experimentation in the United States have emerged principally at the level of the individual states such as California and Colorado. Most evidently, in the California case, acute problems of smog and a concern with the risks of nuclear power provoked specific policies that, over time, became the founda- tion for new action on climate change. But local success in the United States has made little difference at the national level, where the balance of policy constitutes a significant subsidy for fossil fuel and nuclear

issue for techno economical justified Renovation and modernization programme. Ferritic chromium-molybdenum steels (gen- erally referred to as “Cr-Mo” steels) are very much used in the high temperature components of the steam genera- tor/boilers for fossil fuel and nuclear power plant. [1] Gen- erally 1.0 Cr-0.5 Mo steel, 2.25 Cr-1 Mo steel and 9 Cr- 1 Mo steels are used for the construction of superheater Corresponding author: Debashis Ghosh, Central Mechanical Engineering Research Institute (CMERI), CSIR, Durgapur-713209, India; E-mail: dghosh@cmeri.res.in. Received

increase in diffusivity of the Cr in the metal. Töpfer et al. [4] have reported the role of scale growth morphology on high temperature corrosion behavior of deformed speci- men. They have suggested that the increase of chromium in the alloy concentration in spinel phase, decreases the diffusion coefficient of iron and oxygen considerably and therefore reduces the growth kinetics of the outer and inner oxide layer. 2.25 Cr-1 Mo steels are generally preferred in steam generators/boilers for fossil fuel and nuclear power plants [9–11]. However, one of the common

seen generation costs falling over recent years. It is estimated that wind power in many countries is already competitive with fossil fuel and nuclear power if social/environmental costs are considered [23]. Installed cost of wind system is the cost of wind turbine, land, tower, and its accessories and it accounts less any state or federal tax credits. This tax credit may be base on how much wind energy is pumped into the grid or it may be percentage of installed cost. Maintenance cost of wind system is normally very small and annual maintenance cost

, fossil fuel and nuclear power plants 794 US military /10/, and process industries /I I/. Activity of microorganisms is limited not only to iron /12/ and steels /13-17/, but also to other materials: copper /18-257 and its alloys 710,26-287, nickel 7297 and its alloys 7307, aluminum 731,327 and its alloys 733,347 and titanium 728,31,357. Although many billions of dollars have been invested into equipment for oil refineries, chemical plants, and other facilities to protect them from corrosion Vol.27, Nos 1-2. 2009 Mechanisms of Microbiologically Induced Corrosion

- dence over fossil-fuel and nuclear power plants for the first time, and supported this further through a feed-in compensation that made the nationwide operation of photovoltaic and wind power plants economically feasi- ble. After its first amendment in 2004, the EEG began to differentiate between freestanding facilities and solar modules installed on buildings. Lawgivers were quick to recognise the latter as the more sensible approach. The goal of the law was to make the consumption of renewable energies competitive on the energy market by taking advantage of

proposed in theUS [3]. There is 650 thousandkm2 of landsuitable for solar power plants in the southwest of the US. 2.5% of the solar energy available in that area converted to electricity could provide a supply for all of the energy con- sumed in the US. If the extensive lands are covered with solar cell modules and solar heating troughs, electricity can be transferred to all over the country by direct current power transmission. By 2050, a substantial switch from fossil fuels and nuclear power plants to solar power plants could supply 69% of the US’s electricity and 35

Environmentalists in the affluent countries are faced with a perplexing dilemma: how to choose between fossil fuels and nuclear power for future electricity production. Setting aside the option of renewables, which are unlikely to contribute more than a small fraction of the world’s electricity in the foreseeable future, one might describe the dilemma as a “Sophie’s choice” because, to most environmentalists, neither of the two realistic alternatives is acceptable. On one hand, fossil fuels—coal, oil, natural gas—produce greenhouse gases, which most

places where wind is rela- tively consistent and strong and construction permits can be approved. In contrast to fossil fuels and nuclear power, which at present pro- vide about 87 percent of all electricity in the United States and 82 per- cent globally, wind is a clean source of renewable energy that produces no air or water pollution and no greenhouse gases, and the land where wind farms are constructed can also be used for other purposes (agricul- ture and grazing, for example). Because wind is free, operational costs are low relative to many other forms of