Micro Gas Turbine Integrated With a Supercritical CO2 Brayton Cycle Turbine: Layout Comparison and Thermodynamic Analysis

2020 ◽  
Author(s):  
Fabrizio Reale ◽  
Raniero Sannino ◽  
Raffaele Tuccillo
Keyword(s):  
Gas Turbine ◽  
Supercritical Co2 ◽  
Waste Heat ◽  
Thermal Power ◽  
Energy Systems ◽  
Working Fluid ◽  
Small Scale ◽  
Brayton Cycle ◽  
Part Load ◽  
Micro Gas Turbine

Abstract In an energetic scenario where both distributed energy systems and smart energy grids gain increasing relevance, the research focus is also on the detection of new solutions to increase overall performance of small-scale energy systems. Waste heat recovery (WHR) can represent a good solution to achieve this goal, due to the possibility of converting residual thermal power in thermal engine exhausts into electrical power. The authors, in a recent study, described the opportunities related to the integration of a micro gas turbine (MGT) with a supercritical CO2 Brayton Cycle (sCO2 GT) turbine. The adoption of Supercritical Carbon Dioxide (sCO2) as working fluid in closed Brayton cycles is an old idea, already studied in the 1960s. Only in recent years this topic returned to be of interest for electric power generation (i.e. solar, nuclear, geothermal energy or coupled with traditional thermoelectric power plants as WHR). In this technical paper the authors analyzed the performance variations of different systems layout based on the integration of a topping MGT with a sCO2 GT as bottoming cycle; the performance maps for both topping and bottoming turbomachinery have been included in the thermodynamic model with the aim of investigating the part load working conditions. The MGT considered is a Turbec T100P and its behavior at part load conditions is also described. The potential and critical aspects related to the integration of the sCO2 GT as bottoming cycle are studied also through a comparison between different layouts, in order to establish the optimal compromise between overall efficiencies and complexity of the energy system. The off-design analysis of the integrated system is addressed to evaluate its response to variable electrical and thermal demands.

Numerical Study of a Micro Gas Turbine Integrated With a Supercritical CO2 Brayton Cycle Turbine

2018 ◽  
Author(s):  
Fabrizio Reale ◽  
Vincenzo Iannotta ◽  
Raffaele Tuccillo
Keyword(s):  
Gas Turbines ◽  
Waste Heat ◽  
Numerical Study ◽  
Organic Rankine Cycle ◽  
Energy Systems ◽  
Rankine Cycle ◽  
Energy System ◽  
Small Scale ◽  
Brayton Cycle ◽  
Integrated Energy System

The primary need of reducing pollutant and greenhouse gas emissions has led to new energy scenarios. The interest of research community is mainly focused on the development of energy systems based on renewable resources and energy storage systems and smart energy grids. In the latter case small scale energy systems can become of interest as nodes of distributed energy systems. In this context micro gas turbines (MGT) can play a key role thanks to their flexibility and a strategy to increase their overall efficiency is to integrate gas turbines with a bottoming cycle. In this paper the authors analyze the possibility to integrate a MGT with a super critical CO2 Brayton cycle turbine (sCO2 GT) as a bottoming cycle (BC). A 0D thermodynamic analysis is used to highlight opportunities and critical aspects also by a comparison with another integrated energy system in which the waste heat recovery (WHR) is obtained by the adoption of an organic Rankine cycle (ORC). While ORC is widely used in case of middle and low temperature of the heat source, s-CO2 BC is a new method in this field of application. One of the aim of the analysis is to verify if this choice can be comparable with ORC for this operative range, with a medium-low value of exhaust gases and very small power values. The studied MGT is a Turbec T100P.

Cycle Calculations of a Small-Scale Heat Removal System With Supercritical CO2 As Working Fluid

2017 ◽  
Author(s):  
Marcel Strätz ◽  
Jörg Starflinger ◽  
Rainer Mertz ◽  
Michael Seewald ◽  
Sebastian Schuster ◽  
...  
Keyword(s):  
Power Plant ◽  
Supercritical Co2 ◽  
Heat Removal ◽  
Working Fluid ◽  
Small Scale ◽  
Brayton Cycle ◽  
Additional Heat ◽  
Decay Heat ◽  
Heat Removal System ◽  
Removal System

In case of an accident in a nuclear power plant with combined initiating events, (loss of ultimate heat sink and station blackout) additional heat removal system could transfer the decay heat from the core to and diverse ultimate heat sink. On additional heat removal system, which is based upon a Brayton cycle with supercritical CO2 as working fluid, is currently investigated within an EU-funded project, sCO2-HeRo (Supercritical carbon dioxide heat removal system). It shall serve as a self-launching, self-propelling and self-sustaining decay heat removal system to be used in severe accident scenarios. Since a Brayton cycle produces more electric power that it consumes, the excess electric power can be used inside the power plant, e.g. recharging batteries. A small-scale demonstrator will be attached to the PWR glass model at Gesellschaft für Simulatorforschung GfS, Essen, Germany. In order to design and build this small-scale model, cycle calculations are performed to determine the design parameters from which a layout can be derived.

Performance Characteristics of an Operating Supercritical CO2 Brayton Cycle

2012 ◽  
Author(s):  
Thomas Conboy ◽  
Steven Wright ◽  
James Pasch ◽  
Darryn Fleming ◽  
Gary Rochau ◽  
...  
Keyword(s):  
Supercritical Co2 ◽  
Waste Heat ◽  
Electrical Power ◽  
Heat Removal ◽  
Test Facility ◽  
Working Fluid ◽  
Inlet Temperature ◽  
Brayton Cycle ◽  
Compact Size ◽  
Test Loop

Supercritical CO2 (S-CO2) power cycles offer the potential for better overall plant economics due to their high power conversion efficiency over a moderate range of heat source temperatures, compact size, and potential use of standard materials in construction [1,2,3,4]. Sandia National Labs (Albuquerque, NM, US) and the US Department of Energy (DOE-NE) are in the process of constructing and operating a megawatt-scale supercritical CO2 split-flow recompression Brayton cycle with contractor Barber-Nichols Inc. [5] (Arvada, CO, US). This facility can be counted among the first and only S-CO2 power producing Brayton cycles anywhere in the world. The Sandia-DOE test-loop has recently concluded a phase of construction that has substantially upgraded the facility by installing additional heaters, a second recuperating printed circuit heat exchanger (PCHE), more waste heat removal capability, higher capacity load banks, higher temperature piping, and more capable scavenging pumps to reduce windage within the turbomachinery. With these additions, the loop has greatly increased its potential for electrical power generation — according to models, as much as 80 kWe per generator depending on loop configuration — and its ability to reach higher temperatures. To date, the loop has been primarily operated as a simple recuperated Brayton cycle, meaning a single turbine, single compressor, and undivided flow paths. In this configuration, the test facility has begun to realize its upgraded capacity by achieving new records in turbine inlet temperature (650°F/615K), shaft speed (52,000 rpm), pressure ratio (1.65), flow rate (2.7 kg/s), and electrical power generated (20kWe). Operation at higher speeds, flow rates, pressures and temperatures has allowed a more revealing look at the performance of essential power cycle components in a supercritical CO2 working fluid, including recuperation and waste heat rejection heat exchangers (PCHEs), turbines and compressors, bearings and seals, as well as auxiliary equipment. In this report, performance of these components to date will be detailed, including a discussion of expected operational limits as higher speeds and temperatures are approached.

Solar Desalination Based on Micro Gas Turbines Driven by Parabolic Dish Collectors

2019 ◽  
Author(s):  
David Sánchez ◽  
Miguel Rollán ◽  
Lourdes García-Rodríguez ◽  
G. S. Martínez
Keyword(s):  
Gas Turbine ◽  
Reverse Osmosis ◽  
Gas Turbines ◽  
Waste Heat ◽  
Distillation Unit ◽  
Design Parameters ◽  
Small Scale ◽  
Micro Gas Turbine ◽  
The Cost ◽  
The Impact

Abstract This paper presents the preliminary design and techno-economic assessment of an innovative solar system for the simultaneous production of water and electricity at small scale, based on the combination of a solar micro gas turbine and a bottoming desalination unit. The proposed layout is such that the former system converts solar energy into electricity and rejects heat that can be used to drive a thermal desalination plant. A design model is developed in order to select the main design parameters for two different desalination technologies, phase change and membrane desalination, in order to better exploit the available electricity and waste heat from the turbine. In addition to the usual design parameters of the mGT, the impact of the size of the collector is also assessed and, for the desalination technologies, a tailored multi-effect distillation unit is analysed through the selection of the corresponding design parameters. A reverse osmosis desalination system is also designed in parallel, based on commercial software currently used by the water industry. The results show that the electricity produced by the solar micro gas turbine can be used to drive a Reverse Osmosis system effectively whereas the exhaust gases could drive a distillation unit. This would decrease the stack temperature of the plant, increasing the overall energy efficiency of the system. Nevertheless, the better thermodynamic performance of this fully integrated system does not translate into a more economical production of water. Indeed, the cost of water turns out lower when coupling the solar microturbine and Reverse Osmosis units only (between 3 and 3.5 €/m3), whilst making further use the available waste heat in a Multi Effect Distillation system rises the cost of water by 15%.

Off-Design Analysis of a Supercritical CO2 Brayton Cycle with Ambient Air as the Cold Source Driven by Waste Heat from Gas Turbine

2020 ◽  
pp. 1-11
Author(s):  
Jianming Han ◽  
Qingya Ma ◽  
Zihua Wang ◽  
Mengjuan Xu ◽  
Yunfei Song ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Supercritical Co2 ◽  
Waste Heat ◽  
Ambient Air ◽  
Design Analysis ◽  
Brayton Cycle ◽  
Cold Source

Gas Turbine Engine Exhaust Waste Heat Recovery Using Supercritical CO2 Brayton Cycle With Thermoelectric Generator Technology

2015 ◽  
Author(s):  
Francis A. Di Bella
Keyword(s):  
Gas Turbine ◽  
Supercritical Co2 ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Brayton Cycle ◽  
Prime Mover ◽  
Engine Exhaust ◽  
Turbine Engine ◽  
Exhaust Waste Heat

This presentation will discuss the results of the feasibility analysis of a Brayton cycle-based, supercritical CO2 system that recovers waste heat from an MT30 gas turbine used in marine applications. The analysis also included the use of thermoelectric generator (TEG) devices that are one of several direct energy conversion methods known to be applicable to waste heat recovery. The analysis was conducted by Concepts NREC, in collaboration with the Maine Maritime Academy and their principal consultant, Thermoelectric Power Systems, LLC. The feasibility analysis was conducted under Navy SBIR Proposal Number N103-229-0533, entitled “Gas Turbine Engine Exhaust Waste Heat Recovery Shipboard Module Development”. The objective of the project was to improve the energy efficiency of the MT30 prime-mover power system for the Navy and other commercial vessels. The performance goal for the energy recovery system was to improve the fuel economy of the prime mover by 20% when significantly part-loaded.

A Supercritical CO2 Gas Turbine Power Cycle for Next-Generation Nuclear Reactors

2002 ◽  
Author(s):  
Vaclav Dostal ◽  
Michael J. Driscoll ◽  
Pavel Hejzlar ◽  
Neil E. Todreas
Keyword(s):  
Gas Turbine ◽  
Oil Recovery ◽  
Supercritical Co2 ◽  
Power Plants ◽  
Ideal Gas ◽  
Working Fluid ◽  
Inlet Temperature ◽  
Brayton Cycle ◽  
Pinch Point ◽  
Good Efficiency

Although proposed more than 35 years ago, the use of supercritical CO2 as the working fluid in a closed circuit Brayton cycle has so far not been implemented in practice. Industrial experience in several other relevant applications has improved prospects, and its good efficiency at modest temperatures (e.g., ∼45% at 550°C) make this cycle attractive for a variety of advanced nuclear reactor concepts. The version described here is for a gas-cooled, modular fast reactor. In the proposed gas-cooled fast breeder reactor design of present interest, CO2 is also especially attractive because it allows the use of metal fuel and core structures. The principal advantage of a supercritical CO2 Brayton cycle is its reduced compression work compared to an ideal gas such as helium: about 15% of gross power turbine output vs. 40% or so. This also permits the simplification of use of a single compressor stage without intercooling. The requisite high pressure (∼20 MPa) also has the benefit of more compact heat exchangers and turbines. Finally, CO2 requires significantly fewer turbine stages than He, its principal competitor for nuclear gas turbine service. One disadvantage of CO2 in a direct cycle application is the production of N-16, which will require turbine plant shielding (albeit much less than in a BWR). The cycle efficiency is also very sensitive to recuperator effectiveness and compressor inlet temperature. It was found necessary to split the recuperator into separate high- and low-temperature components, and to employ intermediate recompression, to avoid having a pinch-point in the cold end of the recuperator. Over the past several decades developments have taken place that make the acceptance of supercritical CO2 systems more likely: supercritical CO2 pipelines are in use in the western US in oil-recovery operations; 14 advanced gas-cooled reactors (AGR) are employed in the UK at CO2 temperatures up to 650°C; and utilities now have experience with Rankine cycle power plants at pressures as high as 25 MPa. Furthermore, CO2 is the subject of R&D as the working fluid in schemes to sequester CO2 from fossil fuel combustion and for refrigeration service as a replacement for CFCs.

Steady State CFD Investigation of a Radial Compressor Operating With Supercritical CO2

2013 ◽  
Author(s):  
Enrico Rinaldi ◽  
Rene Pecnik ◽  
Pierot Colonna
Keyword(s):  
Steady State ◽  
Critical Point ◽  
Supercritical Co2 ◽  
Tip Clearance ◽  
Working Fluid ◽  
Small Scale ◽  
Brayton Cycle ◽  
Computational Domain ◽  
Proof Of Concept ◽  
Radial Compressor

The supercritical closed Brayton cycle concept is widely recognized as an attractive new option for energy conversion because of the very high-efficiency, reachable at moderate turbine inlet temperature, and the very compact general assembly. Carbon dioxide is chosen as the working fluid because it allows for its compression to occur close to the critical point at suitable temperatures, and high pressure. Compression work is thus small, if compared for instance to air compression. The concept was first studied in the sixties, and recent interest spreading in the scientific and technical community led to the realization of a small-scale proof-of-concept prototype operating at Sandia’s National Laboratories. Moreover, the CSP SunShot project was recently funded by the U.S. National Renewable Energy Laboratory, and it is aimed at the realization of a multi-megawatt concentrating solar power plant, whereby the power block will be a supercritical CO2 Brayton cycle turbine. Other pre-commercial activities are ongoing. This paper focuses on the study of the fluid dynamics of turbomachinery operating with fluids characterized by a complex thermodynamic behavior. The goal is to develop a complete methodology to help the aerodynamic design of scaled-up turbomachinery for supercritical CO2 gas turbine power plants. Starting from a previous analysis of the impeller of the radial compressor of the Sandia proof-of-concept test bench, the new detailed computational domain includes the tip clearance and the vaned diffuser, and has been obtained using an in-house meshing tool suited for turbomachinery geometries. The steady state interface between the impeller and the diffuser is treated with a mixing-plane. In order to correctly calculate the thermophysical properties of the fluid, affected by strong variations close to the critical point, the solver is coupled with an extensive library for the computation of properties of pure fluids and mixtures. An accurate multiparameter equation of state is selected and a look-up table approach is used to speed up the fluid properties evaluation. The results are finally compared with experimental data, and demonstrate the potential of the tool.

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