1,721,012 research outputs found
Preliminary analysis of solarized micro gas turbine application to CSP parabolic dish plants
Full text linkThis work presents a preliminary thermodynamic assessment of a Concentrating solar power (CSP) system made up of a micro gas turbine (MGT) coupled with a parabolic dish concentrator. The thermal engine characteristics are representative of state-of-the art of MGTs (Net power=31.5kWe Turbine Inlet Temperature (TIT)=850°C) while the "solar section" (thermal receiver and parabolic mirror) performance are modelled in accordance with current research outcomes. The overall system is designed and a second law analysis is reported. An estimate of yearly electricity yield is performed (83.98 MWhe) and the obtained sun-to-electricity efficiency (about 18.3%) reveals energetic competiveness with other CSP solutions (parabolic trough and solar tower). A simplified economic analysis (Levelized cost of electricity (LCOE) is 165.7 â¬/MWh) highlights how Solarized Micro Gas Turbine (SMGT) is a promising CSP technology whose improvements perspective can drive dedicated R&D activities
An advanced solution to boost sun-to-electricity efficiency of parabolic dish
No full textThis paper investigates the coupling of parabolic dish concentrator with air micro gas turbine engine (net power output equal to 32.9 kWel). With the aim of increasing the conversion efficiency of the incoming solar radiation, a high temperature system (up to 1100 °C) has been considered: this solution implies the adoption of a ceramic expander coupled with a high temperature indirectly-irradiated solar receiver. A flexible Matlab® suite has been developed for the plant sizing and for the part-load simulation; in addition, the model is able to handle general solar field configurations through the computation of reciprocal shading effect. The obtained yearly sun-to-electric efficiency (26.48%) reveals the energetic advantage over other CSP technologies that can mitigate the technological issues and consequently higher investment cost, related to high operating temperatures. The potential of a hybrid version of the dish is also discussed
Working Fluid Selection and Thermodynamic Optimization of the Novel Renewable Energy-Based RESTORE Seasonal Storage Technology
Full text linkSeasonal-based energy storage is expected to be one of the main options for the decarbonization of the space heating sector by increasing the renewables dispatchability. Technologies available today are mainly based on hot water and can only partially fulfill the efficiency, energy density and affordability requirements. This work analyzes a novel system based on pumped thermal energy storage (PTES) concept to maximize renewables and waste heat exploitation during summer and make them available during winter. Organic fluid-based cycles are adopted for the heat upgrade during hot season (heat pump (HP)) and to produce electricity and hot water during cold season (power unit (PU)). Upgraded thermal energy drives an endothermic reaction producing dehydrated solid salts, which can be stored for months using inexpensive and high energy density solutions. This paper focuses on thermodynamic cycles design, comparing the performance attainable with several working fluids. Two different configurations are investigated: coupled systems, sharing the fluid and heat exchangers in both operating modes, and decoupled systems. A preliminary economic assessment completes the study, including a sensitivity analysis on electricity and heat prices. Cyclopentane is identified as a promising working fluid for coupled systems, reaching competitive round trip efficiencies (RTEs), maximizing the ratio between performance and HX surfaces, without excessive turbomachinery volume ratios and volumetric flows. Economic analysis shows that solutions with lower efficiency, but also lower capital cost, can achieve competitive payback times (PBT). On the contrary, decoupled systems are less attractive, as they reach slightly higher thermodynamic performance, but require higher capital costs, possibly being of interest only in specific applications
Working Fluid Selection and Thermodynamic Optimization of the Novel Renewable-Energy Based RESTORE Seasonal Storage Technology
No full textMicroalgae cofiring in coal power plants: Innovative system layout and energy analysis
No full textThis paper investigates the smart integration of a 500 ha microalgae culturing facility with a large scale coal power plant (758.6 MWe): a fraction of the CO2 contained in the coal plant flue gases is used for the algal cultivation, a fraction of the low-temperature flue gas heat available is used for the biomass drying, finally the produced biomass is co-fired in the coal plant. The produced algal biomass represents approximately 1% of the boiler heat input.Through the solution of energy and mass balances of each plant component, the overall system performances in terms of net energy ratio (NER) and CO2 emissions reduction are obtained. The computed NER (1.92) guarantees an energy harvest almost twice the energetic cost needed to produce the microalgal fuel. The total CO2 emissions are reduced of approximately 0.48%, identifying microalgae cofiring as a solution able to reduce the environmental impact of electricity generation. A simplified economic analysis has allowed an estimate of the algal system investment cost (about 235 k€ ha-1) and of the levelized cost of electricity (LCOE) (554.4 € MWh-1). A set of sensitivity analyses is finally performed to investigate the influence of the initial hypotheses on the results
Development of an innovative code for the design of thermodynamic solar power plants part A: Code description and test case
No full textComparison of Two Linear Collectors in Solar Thermal Plants: Parabolic Trough Versus Fresnel
No full textSemi-Closed Oxy-Combustion Combined Cycles for Combined Heat and Power Applications
No full textThis study focuses on the design and comparison of three utility-scale combined heat and power (CHP) cycles with carbon capture and storage (CCS): (i) a CHP semi-closed oxy-combustion combined cycle (SCOC-CC), (ii) a CHP natural gas combined cycle (NGCC) with postcombustion CCS, and (iii) a CHP NGCC with postcombustion CCS and supplementary firing. Performance evaluations are conducted at the design point and partial load (gas turbine at 30%) for different exports of high-temperature pressurized steam. The comparison is extended against two reference separate production systems with CCS, one based on postcombustion technologies, and another based on oxy-combustion. Simulations of the H-class gas turbines are performed using gas steam (GS), a specific in-house validated software, while the heat recovery steam cycle is modeled using Thermoflex. The CO2 capture processes employ validated models in Aspen Plus. The results highlight the suitability of the SCOC-CC for CHP applications, demonstrating superior performance and flexibility compared to CHP postcombustion technologies at both nominal and minimum loads. The SCOC cycle achieves a maximum first-law efficiency of 65.95%, outperforming CCS technologies that generate electricity and heat separately and enabling fuel savings up to 9.2%
Semi-Closed Oxy-Combustion Combined Cycles (SCOC-CC) for Combined Heat and Power Applications
No full textComparison of linear and point focus collectors in solar power plants
Full text linkSolar tower based plants are seen as a promising technology to reduce the cost of electricity from solar radiation. This paper
assesses the design and overall yearly performances of two different solar tower concepts featuring two commercial plants
running in Spain. The first plant investigated is based on Direct Steam Generation and a cavity receiver (PS-10 type). The second
plant considers an external cylindrical receiver with molten salts as heat transfer fluid and storage system (Gemasolar type).
About the optical assessment performed with DELSOL3, a calibration of heliostat aim points was performed to match available
flux maps on the receiver. Moving to results, the PS-10 type has higher optical performances both nominal design and yearly
average. This is due both to the field size and orientation which guarantee a higher efficiency and to the receiver concept itself.
About power production, the molten salts allow higher temperature and consequently conversion efficiency than PS-10. The
solar-to-electricity efficiency is equal to 18.7% vs. 16.4% of DSG cavity plant. The obtained results are strictly related to the set
of assumptions made on each plant component: when available real plant data where used. The two solar tower plants results
were also compared to corresponding commercial linear focus plants featuring the same power block concept. Gemasolar type
shows a higher solar-to-electricity efficiency compared to a parabolic trough plant with storage (18.7% vs. 15.4%) because of the
higher maximum temperatures and, consequently, power block efficiency. PS-10 is better than a linear Fresnel DSG (16.4% vs.
10.4%) because of the higher optical performances
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