Preliminary analysis of solarized micro gas turbine application to CSP parabolic dish plants

This 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\u82¬/MWh) highlights how Solarized Micro Gas Turbine (SMGT) is a promising CSP technology whose improvements perspective can drive dedicated R&D activities

Comparison of linear and point focus collectors in solar power plants

AbstractSolar 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

Off-design study of a waste heat recovery ORC module in gas pipelines recompression station

This study investigates the use of an ORC as heat recovery unit in a natural gas pipeline compression station powered by a gas turbine with the aim of increasing the process energy efficiency. A flexible Matlab® suite, able to investigate both subcritical and supercritical cycle, has been developed for the plant sizing and for the part-load simulation. The methodology to compute the system energetic performance is discussed. The ORC configuration that guarantees the maximum power output (7.22 MWe) is identified. The yearly electricity yield (42615.9 MWh) reveals good perspectives of implementing ORC with the aim of reducing the environmental impact of gas compression stations

Solar Volumetric Receiver Coupled to a Parabolic Dish: Heat Transfer and Thermal Efficiency Analysis

[EN]Concentrated Solar Power plants are commonly recognized as one of the most attractive options within carbon free power generation technologies because their high efficiency and also because implementation of hybridization and/or storage is feasible. In this work a small-scale system focused on distributed production, in the range of kWe (5kWe to 30kWe), is modeled. A parabolic dish collects direct solar power towards a receiver located at its focus. There, the heat transfer fluid increases its temperature for thermal storage or for directly producing electricity at the power block. Thus, this is a crucial component in CSP systems since it greatly influences global efficiency. There is a trade-off in the energy balance within the thermal receiver, since the higher the temperatures it achieves, the higher the radiation losses could be. In this work, a heat transfer analysis for an air volumetric receiver coupled to a parabolic dish is carried out. The solar receiver is modeled under steady-state conditions using a detailed set of equations. The model considers the main losses by convection, conduction and radiation at the glass window and the surrounding insulator. The temperatures and heat transfers along the different receiver zones are computed with a built from scratch in-house code programmed in Mathematica®. The thermal efficiency mainly depends on the incoming solar irradiance at the glass window, the receiver geometry and the type of materials considered, as well as on the ambient temperature. It is expected that this model (precise but not too expensive from the computational viewpoint) could help to identify the main bottlenecks

Modeling a solar pressurized volumetric receiver integrated in a parabolic dish: Off-design heat transfers, temperatures, and efficiencies

[EN]Concentrated solar power plants are commonly recognized as one of the most attractive options within carbonfree power generation technologies because of their high efficiency and feasible hybridization and/or storage implementation. In this work, a complete heat transfer analysis for an air volumetric receiver coupled to a parabolic dish focused on distributed generation (in the range of kWe) is carried out. It includes most relevant heat losses. Dish collector optical efficiency is computed by means of a ray-tracing software while the thermal performance of the solar receiver is modeled under steady-state conditions using a comprehensive set of equations with a clear physical origin and meaning. Detailed information on the temperatures and heat transfers along the different inner and outer receiver zones are computed with a built from scratch inhouse code programmed in Mathematica®. The model considers the main losses from convection, conduction and radiation and through the surrounding insulator. The resulting thermal efficiency mainly depends on the incoming solar irradiance at the glass window, the receiver geometry and the type of materials considered, as well as on the ambient temperature. Explicit numerical results are given at two locations under different meteorological conditions. Optical efficiencies reach values of about 84%. For irradiance values around 800– 900 W/m2, at the receiver outlet, air can reach temperatures of about 1200 K and receiver thermal efficiency is over 80%. It is expected that this model (precise but not too expensive from the computational viewpoint) could help to identify the main efficiency bottlenecks, paving the way for optimization when designing this type of concentrated solar plants through further coupling with a power block, as Brayton or other cycles

Comparison of linear and point focus collectors in solar power plants

open4Solar 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.Successivamente pubblicato su ENERGY PROCEDIA (2014)Rinaldi, F.; Binotti, M.; Giostri, A.; Manzolini, G.Rinaldi, F.; Binotti, Marco; Giostri, Andrea; Manzolini, Giampaol

An advanced solution to boost sun-to-electricity efficiency of parabolic dish

This 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