Design Performance Analysis of Supercritical CO2 Cycle for CSP Application With Sensible Heat Thermal Storage

2021 ◽  
Author(s):  
Dhinesh Thanganadar ◽  
Francesco Fornarelli ◽  
Sergio Camporeale ◽  
Jonathon Gillard ◽  
Kumar Patchigolla
Keyword(s):  
Supercritical Co2 ◽  
Power Plants ◽  
Storage System ◽  
Operating Cost ◽  
Capital Cost ◽  
Specific Power ◽  
Inlet Temperature ◽  
Power Cycle ◽  
Power Block ◽  
C 50

Abstract Supercritical CO2 (sCO2) cycles can achieve higher efficiencies than steam Rankine cycles at a higher temperature with a compact plant footprint. Concentrated solar power plants are capital intensive, as there is no fuel-related operating cost, the capital cost must be reduced to realise a reduction in the levelised cost of electricity. Power cycle efficiency and the temperature difference between the hot and cold storage tanks are the critical thermodynamic parameters to reduce the size and the cost of solar field and two-tank storage system whilst the power cycle specific power has also to be maximised to lower the power block cost. With these objectives, three potential cycle configurations were selected for detail assessment; a recompression cycle, partial cooling cycle and a partial heating cycle. A set of performance maps are presented using multi-objective optimisation, which maximises the efficiency and the specific power is explored for five different compressor inlet temperature of 35°C, 40°C, 45°C, 50°C, 55°C and two turbine inlet temperatures of 600°C and 700°C. The overnight capital cost across the Pareto front are estimated and the economic performance map is presented, which guides in selecting an optimal design for different boundary conditions.

Analytical Formulation of the Performance of the Allam Power Cycle

2020 ◽  
Author(s):  
Yousef Haseli
Keyword(s):  
Power Plants ◽  
Fossil Fuels ◽  
Air Separation ◽  
Working Fluid ◽  
Inlet Temperature ◽  
Separation Unit ◽  
Power Cycle ◽  
Functional Relationships ◽  
Oxyfuel Combustion ◽  
Co2 Flow

Abstract Thermal power plants operating on fossil fuels emit a considerable amount of polluting gases including carbon dioxide and nitrogen oxides. Several technologies have been developed or under development to avoid the emissions of, mainly, CO2 that are formed as a result of air-fuel combustion. While post-combustion capture methods are viable solutions for reduction of CO2 in the existing power plants, implementation of the concept of oxyfuel combustion in future power cycles appears to be a promising technique for clean power generation from fossil fuels. A novel power cycle that employs oxyfuel combustion method has been developed by NET Power. Known as the Allam cycle, it includes a turbine, an air separation unit (ASU), a combustor, a recuperator, a water separator, CO2 compression with intercooling and CO2 pump. (Over 90% of the supercritical CO2 flow is recycled back to the cycle as the working fluid, and the rest is extracted for further processing and storage. The present paper introduces a simplified thermodynamic analysis of the Allam power cycle. Analytical expressions are derived for the net power output, optimum turbine inlet temperature (TIT), and the molar flowrate of the recycled CO2 flow. The study aims to provide a theoretical framework to help understand the functional relationships between the various operating parameters of the cycle. The optimum TIT predicted by the presented expression is 1473 K which is fairly close to that reported by the cycle developers.

A Comparison Study for Off-Design Performance Prediction of a Supercritical CO2 Compressor With Similitude Analysis

2019 ◽  
Author(s):  
Yongju Jeong ◽  
Seongmin Son ◽  
Seong kuk Cho ◽  
Seungjoon Baik ◽  
Jeong Ik Lee
Keyword(s):  
Critical Point ◽  
Supercritical Co2 ◽  
Power Plants ◽  
Cycle Performance ◽  
Working Fluid ◽  
Brayton Cycle ◽  
Power Cycle ◽  
Design Performance ◽  
Wide Range ◽  
Phase Fluid

Abstract Most of the power plants operating nowadays mainly have adopted a steam Rankine cycle or a gas Brayton cycle. To devise a better power conversion cycle, various approaches were taken by researchers and one of the examples is an S-CO2 (supercritical CO2) power cycle. Over the past decades, the S-CO2 power cycle was invented and studied. Eventually the cycle was successful for attracting attentions from a wide range of applications. Basically, an S-CO2 power cycle is a variation of a gas Brayton cycle. In contrast to the fact that an ordinary Brayton cycle operates with a gas phase fluid, the S-CO2 power cycle operates with a supercritical phase fluid, where temperatures and pressures of working fluid are above the critical point. Many advantages of S-CO2 power cycle are rooted from its novel characteristics. Particularly, a compressor in an S-CO2 power cycle operates near the critical point, where the compressibility is greatly reduced. Since the S-CO2 power cycle greatly benefits from the reduced compression work, an S-CO2 compressor prediction under off-design condition has a huge impact on overall cycle performance. When off-design operations of a power cycle are considered, the compressor performance needs to be specified. One of the approaches for a compressor off-design performance evaluation is to use the correction methods based on similitude analysis. However, there are several approaches for deriving the equivalent conditions but none of the approaches has been thoroughly examined for S-CO2 conditions based on data. The purpose of this paper is comparing these correction models to identify the best fitted approach, in order to predict a compressor off-design operation performance more accurately from limited amount of information. Each correction method was applied to two sets of data, SCEIL experiment data and 1D turbomachinery code off-design prediction code generated data, and evaluated in this paper.

scholarly journals A Discussion of Possible Approaches to the Integration of Thermochemical Storage Systems in Concentrating Solar Power Plants

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4940
Author(s):  
Michela Lanchi ◽  
Luca Turchetti ◽  
Salvatore Sau ◽  
Raffaele Liberatore ◽  
Stefano Cerbelli ◽  
...  
Keyword(s):  
Power Plants ◽  
Solar Power ◽  
Storage Systems ◽  
Storage System ◽  
Reactive Systems ◽  
Operating Conditions ◽  
Storage Unit ◽  
Power Block ◽  
Solar Plant ◽  
Term Energy

One of the most interesting perspectives for the development of concentrated solar power (CSP) is the storage of solar energy on a seasonal basis, intending to exploit the summer solar radiation in excess and use it in the winter months, thus stabilizing the yearly production and increasing the capacity factor of the plant. By using materials subject to reversible chemical reactions, and thus storing the thermal energy in the form of chemical energy, thermochemical storage systems can potentially serve to this purpose. The present work focuses on the identification of possible integration solutions between CSP plants and thermochemical systems for long-term energy storage, particularly for high-temperature systems such as central receiver plants. The analysis is restricted to storage systems potentially compatible with temperatures ranging from 700 to 1000 °C and using gases as heat transfer fluids. On the basis of the solar plant specifications, suitable reactive systems are identified and the process interfaces for the integration of solar plant/storage system/power block are discussed. The main operating conditions of the storage unit are defined for each considered case through process simulation.

Oxy-fuel Combustion Power Cycles: A Sustainable Way to Reduce Carbon Dioxide Emission

2021 ◽  
Author(s):  
Anand Pavithran ◽  
Meeta Sharma ◽  
Anoop Kumar Shukla
Keyword(s):  
Carbon Dioxide ◽  
Carbon Capture ◽  
Power Plants ◽  
Fossil Fuels ◽  
Storage System ◽  
Carbon Capture And Storage ◽  
Energy Generation ◽  
Fuel Combustion ◽  
Power Cycles ◽  
Power Cycle

The energy generation from the fossil fuels results to emit a tremendous amount of carbon dioxide into the atmosphere. The rise in the atmospheric carbon dioxide level is the primary reason for global warming and other climate change problems for which energy generation from renewable sources is an alternative solution to overcome this problem. However, the renewables sources are not as reliable for the higher amount of energy production and cannot fulfil the world’s energy demand; fossil fuels will continue to be consumed heavily for the energy generation requirements in the immediate future. The only possible solution to overcome the greenhouse gas emission from the power plant is by capturing and storing the carbon dioxide within the power plants instead of emitting it into the atmosphere. The oxy-fuel combustion power cycle with a carbon capture and storage system is an effective way to minimize emissions from the energy sectors. The oxy-fuel power cycle can reduce 90–99% of carbon dioxide emissions from the atmosphere. Moreover, the oxy-fuel power cycles have several advantages over the conventional power plants, these include high efficiency, lesser plant footprint, much easier carbon-capturing processes, etc. Because of these advantages, the oxy-fuel combustion power cycles capture more attention. In the last decades, the number of studies has risen exponentially, leading to many experimental and demonstrational projects under development today. This paper reviews the works related to oxy-fuel combustion power generation technologies with carbon capture and storage system. The cycle concepts and the advancements in this technology have been briefly discussed in this paper.

Thermal Analysis and Pressure Loss Modeling for an Optimized Heat Exchanger Used in a Recuperated CO2 Power Cycle

2018 ◽  
Author(s):  
Husam Zawati ◽  
Michael Elmore ◽  
Jayanta Kapat ◽  
Narasimha Nagaiah
Keyword(s):  
Thermal Analysis ◽  
Heat Exchanger ◽  
Initial Pressure ◽  
Specific Power ◽  
Inlet Temperature ◽  
Geometrical Parameters ◽  
Area Density ◽  
Pressure Drops ◽  
Power Cycle ◽  
Net Power Output

A simple recuperated cycle is studied and optimized in this paper. Geometrical parameters for a novel recuperator design are then optimized to minimize area density. The recuperator is where the s-CO2 is analyzed and simulated for both hot and cold sides. The design of the cycle is obtained through a study of a 100 MW net power output s-CO2 cycle, where this cycle features a turbine inlet temperature of 1023 K. The main objective of this paper is to couple a recuperated cycle with a heat exchanger. This is done through Pareto optimality to study the tradeoffs between conflicting variables. The geometry of the heat exchanger features two inlet headers attached to semirectangular channels. The thermal analysis used is based on one-dimensional finite enthalpy method, where discretization is made by equal heat transferred per element. In addition, pressure drops are calculated at both sides of main heat exchanger body. Optimized cycle based on practical parametric assumptions reveals an efficiency of 45.8% and specific power of 132.1 kJ/kg. Best design reveals channel side length of 7 mm with surrounding solid sidewall thickness of 1 mm. Pressure drops for the proposed design are 4.8% and 0.6% of the initial pressure for the hot and the cold sides, respectively. Overall length of the heat exchanger is found to be 10.7 m with an effectiveness of 96.2% and an area density of 363 m2/m3.

A Novel Supercritical CO2 Power Cycle for Energy Conversion in Fusion Power Plants

2013 ◽  
Vol 64 (3) ◽  
pp. 483-487 ◽  
Author(s):  
I. P. Serrano ◽  
J. I. Linares ◽  
A. Cantizano ◽  
B. Y. Moratilla
Keyword(s):  
Energy Conversion ◽  
Supercritical Co2 ◽  
Power Plants ◽  
Fusion Power ◽  
Power Cycle

Computational Modeling of a 1MW Scale Combustor for a Direct Fired sCO2 Power Cycle

2018 ◽  
Author(s):  
Jacob Delimont ◽  
Nathan Andrews ◽  
Lalit Chordia
Keyword(s):  
Carbon Capture ◽  
Power Plants ◽  
Fossil Fuels ◽  
Combustion Process ◽  
Combined Cycle ◽  
Cfd Modeling ◽  
Inlet Temperature ◽  
Power Cycle ◽  
Natural Gas Combined Cycle ◽  
Cycle Efficiency

Direct fired oxy-fuel combustion provides a promising method for heat addition into a supercritical carbon dioxide (sCO2) power cycle. Using this method of thermal energy input into the cycle allows for potentially higher fuel to bus bar cycle efficiency. In addition, the nature of the sCO2 power cycle lends itself to easy and efficient capture of 99% of the CO2 generated in the combustion process. sCO2 power cycles typically operate at pressures above 200 bar, and due to the high degree of recuperation found in these cycles, have a very high combustor inlet temperature. Past works have explored combustor inlet temperatures high enough to be in the autoignition regime. The inlet temperatures which will be explored in this work will be limited to 700°C, which will allows for very different combustor geometry than that which has been studied in the past. While this combustor inlet temperature is lower than that previously studied, when combined with the extremely high pressure, this poses several unique and difficult design challenges. In order to explore these unique design conditions a reliable and robust CFD solution method was developed. This reliable CFD solution methodology enables rapid iteration on various geometries. This paper will explore the CFD modeling setup and the assumptions which were made in the absence of well experimental data in this combustor regime. Exploration of methodology to account for possible variations in chemical kinetics due to the lack of validated kinetic models in the current literature will also be discussed. The results from the CFD runs will be discussed and the combustor design, and next steps to complete a detailed combustor design will also be discussed. This work will enable future work in the development of oxy-fuel combustors for direct fired sCO2 power. This promising technology enables the use of fossil fuels with up to 99% carbon capture, while maintaining an overall cycle efficiency competitive with natural gas combined cycle power plants.

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.

Evaluation of the Optimal Point Variation of the S-CO2 Cycle While Considering Internal Pinch in Recuperator

2018 ◽  
Author(s):  
Seongmin Son ◽  
Jin Young Heo ◽  
Jeong Ik Lee
Keyword(s):  
Specific Heat ◽  
Critical Point ◽  
Supercritical Co2 ◽  
Waste Heat ◽  
Working Fluid ◽  
Point Problem ◽  
Inlet Temperature ◽  
Pinch Point ◽  
Optimal Point ◽  
Power Cycle

The Supercritical CO2 power cycle (S-CO2 cycle) is the power cycle that adopts CO2 as a working fluid and is designed to have a compression process near the critical point of CO2. Due to the non-linearity of CO2 pyhsical properties near the critical point, the S-CO2 cycle needs relatively less compression work. Therefore, the efficiency of the S-CO2 cycle is higher than traditional gas cycles. Furthermore, because of the relatively high system minimum pressure (near the critical point, ∼7.39 MPa), an S-CO2 cycle can be composed of smaller turbomachines. Considering these advantages, nowadays, there are many attempts to apply S-CO2 cycles to various fields, such as waste heat recovery, nuclear, coal, concentrated solar power plant and so on. These non-linear pyhsical properties become the cause of some unique issues. One of the most significant issues is the internal pinch point problem in a recuperator. Unlike the traditional gas-to-gas heat exchanger, each hot and cold side of the S-CO2 recuperator goes through the severe change of specific heat. This dramatic change of specific heat may cause the internal pinch point of the recuperator. When the internal pinch point phenomenon occurs, the performance of the recuperator may not able to be evaluated from the pre-fixed effectiveness. This can be an issue when the compressor inlet temperature decreases to transcritical or subcritical region. This may alter the optimal point of the S-CO2 power cycle. In this paper, optimal design points and optimal performance of the S-CO2 power cycle are tracked with the consideration of the internal pinch point phenomenon. While changing the system boundary conditions, the optimal point variation due to internal pinch point phenomenon is evaluated and compared with a traditional methodology. This research is progressed with an in-house integrated S-CO2 power cycle analysis code, which is named KAIST – ESCA (Evaluator for Supercritical CO2 Cycle based on Adjoint method). The target cycle layouts are Simple Recuperated, Intercooling, Recompression and Recompression with intercooling layouts. Both of the S-CO2 Rankine and Brayton cycles conditions are considered.

Modelling of Gas Cooler for S-CO2 Brayton Power Cycle

2019 ◽  
Author(s):  
Vivek Pandey ◽  
Lakshminarayanan Seshadri ◽  
Jayesh Gupta ◽  
Ravishankar Mariayyah ◽  
Nagavally Lingappa Santhosh ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Power Plants ◽  
Design Tool ◽  
Power Cycles ◽  
Power Cycle ◽  
Power Block ◽  
Property Data ◽  
Scale Modelling ◽  
Geometrical Information ◽  
High Degree

Abstract Supercritical Carbon dioxide (S-CO2) based Brayton power plants are being extensively researched as an alternative to steam-based power cycles due to high degree of recuperation favoured by higher heat capacities in supercritical state. Several studies revealed that PCHEs are suitable candidate for S-CO2 applications. Although, PCHEs have been well researched for various applications, there is very little information pertaining to the design or performance of PCHEs in S-CO2 applications. This paper presents a novel methodology for design of a PCHE as gas cooler for a S-CO2 power block. In the first part, a thermal resistance network (TRN) model developed using MATLAB is used for full scale modelling of gas cooler. The geometrical information obtained from TRN model is used to optimize the overall footprint. In the second part, the MATLAB code coupled with a 1-D design tool (Flownex SE) and an optimization software; Isight, is used to optimize the inlet-exit manifold based on flow admittance approach. The 1-D design tool discretizes the inlet-exit manifolds to achieve optimum combination of flow admittances which facilitates identical channel mass flow rate and inlet pressure across each channel/stack ensuring minimum overall pressure drop. In the current paper a case study for a 10 MW PCHE based gas cooler used in a simple recuperated S-CO2 cycle rejecting heat to ambient at 45 °C and 90 bar, is presented. The gas cooler uses water as the primary heat transfer maintained at 4 bar pressure to facilitate single phase heat transfer. Pinch temperature of 5 K is assumed to exist in all heat transfer surfaces. The MATLAB program is coupled with REFPROP property data base to retrieve the thermodynamic properties across all the nodes.

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