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UN MODELLO MATEMATICO DI SUPPORTO ALLE TECNOLOGIE DEL SOLARE TERMODINAMICO A CONCENTRAZIONE
No full textIntegrazione tra turbine a gas e collettori parabolici lineari in impianti solari a concentrazione
No full text
Integrazione tra turbine a gas e colettori parabolico lineari in impianti solari a concetrazione
No full textA new conversion section for Parabolic Trough - Concentrated Solar Power (CSP-PT) plants
No full textOne of the most important challenge of our future is the balance between energy needs and production, in the framework of the CO2 commitments almost universally adopted or declared. As shown in [1], the total energy consumption is still a prerogative of fossil fuels, with a share close to 90 %; renewable energy, apart from the energy production from hydro, photovoltaic, biomass, waste and others, reach for 3-4 % since many years. This discouraging result calls for new conversion technologies based on renewables, if the concept of sustainability is really adopted.
Concentrated Solar Power (CSP) plants technology could make the difference with respect to the other renewable technologies, thanks to “hybridity” in combining the concentrated solar energy source and the conventional power generation (actually steam turbine plants as energy conversion section). In the sector of energy production, parabolic through (PT) type is more promising.
Recently, the Authors showed in [2,3] how convenient could be the utilization of gases as Heat Transfer Fluid, HTF, with advantages from a technological point of view in the heat collector section and, mainly, from the conversion section point of view, having the possibility to use gas turbines in which the HTF directly expands.
In this work, the Authors discuss some thermodynamic and engineering aspects concerning the use of gases as HTF, limiting the attention to air and CO2 and they further discuss the performances of an innovative gas turbine power plant. It is based on a sequence of compressions and expansions, intercooled and reheated (inside linear solar receivers) respectively, in order to increase cycle specific work and efficiency. The paper focuses the attention on the optimum number of compressions and expansions: when it changes, pressure levels change too, requiring a series of reheating processes which operate in parallel, so increasing the overall solar receiver length and, definitively, investment costs. The optimization has been done adopting as design parameter the collector length per unit power which is the most sensible parameter defining investment cost
Gases as Working Fluid in Parabolic Trough CSP Plants
Full text linkAbstractThe energetic dimension of actual economy is massively oriented towards the use of fossil fuels: they cover a share of 87% of the energy needs and the trend of this share is increasing, in spite of the commitments adopted by almost all the Countries in the World. Most crucial concern is CO2 levels in the atmosphere and the positive feedback between Earth's temperature increase and carbon. Actual technologies which make use of renewable sources seem to be not fully suitable to invert this continuous increase of fossil fuels.Concentrated Solar Power plants (CSP) have had, recently, a huge attention as a technology able to give, in the mean future, a strong contribution to the electrical energy generation. CSP technology has an intrinsic superiority with respect to the other renewable plants but actual plants suffer of many drawbacks which slow down a massive diffusion: these aspects increase costs and do not insure the reliability levels required to make the investments profitable.Gas as heat transfer fluid inside solar receiver in a CSP Parabolic Trough (PT) type plant is discussed in this paper: this would simplify actual technology in the conversion section, downstream the solar energy collecting phase. The use of gases calls for a new conversion section discussed in this paper based on a direct expansion in gas turbine plants.The success of this concept is related to the possibility to increase the fluid (gas) temperature above the actual operating maximum values. The paper discusses the performances of a new gas cycle, the performances of actual receivers when fed with gas and introduces and discusses an optimization design parameter which allows a cost decrease and industrial reliability improvement
A definitive model of a small-scale concentrated solar power hybrid plant using air as heat transfer fluid with a thermal storage section and ORC plants for energy recovery
No full textThe aim of this work was to propose a small-scale Concentrated Solar Power plant using conventional technologies, in order to improve their flexibility and performances, and reinforce their competitiveness compared to traditional systems. Additionally, this study analyzed the possibility of providing continuity of energy production through an optimized hybrid system, which considered thermal energy storage from a gaseous Heat Transfer Fluid, air. It also considered the possibility of recovering part of the energy of the thermodynamic cycle through an Organic Rankine Cycle system with appropriate dimensions. The final outcomes were a 170 kW CSP plant with about 805 MWh of annual electricity production with a global solar capacity of 32.5%, about 900 kWh of thermal storage daily capacity, and an ORC recovery section of 54.2 kW with a specific production of 260 MWh/y
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