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.

Comparison of Supercritical CO2 Power Cycles to Steam Rankine Cycles in Coal-Fired Applications

2017 ◽  
Author(s):  
Jason D. Miller ◽  
David J. Buckmaster ◽  
Katherine Hart ◽  
Timothy J. Held ◽  
David Thimsen ◽  
...  
Keyword(s):  
Power Plants ◽  
Cooling Tower ◽  
Test Case ◽  
Test Cases ◽  
Power Cycles ◽  
Air Preheater ◽  
Power Cycle ◽  
Inlet Conditions ◽  
Cycle Efficiency ◽  
Steam Plant

Increasing the efficiency of coal-fired power plants is vital to reducing electricity costs and emissions. Power cycles employing supercritical carbon dioxide (sCO2) as the working fluid have the potential to increase power cycle efficiency by 3–5% points over state-of-the-art oxy-combustion steam-Rankine cycles operating under comparable conditions. To date, the majority of studies have focused on the integration and optimization of sCO2 power cycles in waste heat, solar, or nuclear applications. The goal of this study is to demonstrate the potential of sCO2 power cycles, and quantify the power cycle efficiency gains that can be achieved versus the state-of-the-art steam-Rankine cycles employed in oxy-fired coal power plants. Turbine inlet conditions were varied among the sCO2 test cases and compared with existing Department of Energy (DOE)/National Energy Technology6 Laboratory (NETL) steam base cases. Two separate sCO2 test cases were considered and the associated flow sheets developed. The turbine inlet conditions for this study were chosen to match conditions in a coal-fired ultra-supercritical steam plant (Tinlet = 593°C, Pinlet = 24.1 MPa) and an advanced ultra-supercritical steam plant (Tinlet = 730°C, Pinlet = 27.6 MPa). A plant size of 550 MWe, was selected to match available information on existing DOE/NETL bases cases. The effects of cycle architecture, combustion-air preheater temperature, and cooling source type were considered subject to comparable heat source and reference conditions taken from the steam Rankine reference cases. Combinations and variants of sCO2 power cycles — including cascade and recompression and variants with multiple reheat and compression steps — were considered with varying heat-rejection subsystems — air-cooled, direct cooling tower, and indirect-loop cooling tower. Where appropriate, combustion air preheater inlet temperature was also varied. Through use of a multivariate nonlinear optimization design process that considers both performance and economic impacts, curves of minimum cost versus efficiency were generated for each sCO2 test case and combination of architecture and operational choices. These curves indicate both peak theoretical efficiency and suggest practical limits based on incremental cost versus performance. For a given test case, results for individual architectural and operational options give insight to cost and performance improvements from step-changes in system complexity and design, allowing down selection of candidate architectures. Optimized designs for each test case were then selected based on practical efficiency limits within the remaining candidate architectures and compared to the relevant baseline steam plant. sCO2 cycle flowsheets are presented for each optimized design.

Application of Supercritical Fluids in Thermal- and Nuclear-Power Engineering

2021 ◽  
pp. 601-658
Author(s):  
Igor L. Pioro
Keyword(s):  
Heat Transfer ◽  
Carbon Dioxide ◽  
Supercritical Fluids ◽  
Nuclear Power ◽  
Power Plants ◽  
Thermal Power ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Thermal Power Plants ◽  
Power Cycles

Supercritical Fluids (SCFs) have unique thermophyscial properties and heat-transfer characteristics, which make them very attractive for use in power industry. In this chapter, specifics of thermophysical properties and heat transfer of SCFs such as water, carbon dioxide, and helium are considered and discussed. Also, particularities of heat transfer at Supercritical Pressures (SCPs) are presented, and the most accurate heat-transfer correlations are listed. Supercritical Water (SCW) is widely used as the working fluid in the SCP Rankine “steam”-turbine cycle in fossil-fuel thermal power plants. This increase in thermal efficiency is possible by application of high-temperature reactors and power cycles. Currently, six concepts of Generation-IV reactors are being developed, with coolant outlet temperatures of 500°C~1000°C. SCFs will be used as coolants (helium in GFRs and VHTRs, and SCW in SCWRs) and/or working fluids in power cycles (helium, mixture of nitrogen (80%) and helium (20%), nitrogen and carbon dioxide in Brayton gas-turbine cycles, and SCW/“steam” in Rankine cycle).

Application of Supercritical Pressures in Power Engineering

2017 ◽  
pp. 404-457
Author(s):  
Igor Pioro ◽  
Mohammed Mahdi ◽  
Roman Popov
Keyword(s):  
Heat Transfer ◽  
Carbon Dioxide ◽  
High Temperature ◽  
Gas Turbine ◽  
Power Plants ◽  
Thermal Power ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Thermal Power Plants ◽  
Power Cycles

SuperCritical Fluids (SCFs) have unique thermophyscial properties and heat-transfer characteristics, which make them very attractive for use in power industry. In this chapter, specifics of thermophysical properties and heat transfer of SCFs such as water, carbon dioxide and helium are considered and discussed. Also, particularities of heat transfer at SuperCritical Pressures (SCPs) are presented, and the most accurate heat-transfer correlations are listed. SuperCritical Water (SCW) is widely used as the working fluid in the SCP Rankine “steam”-turbine cycle in fossil-fuel thermal power plants. This increase in thermal efficiency is possible by application of high-temperature reactors and power cycles. Currently, six concepts of Generation-IV reactors are being developed, with coolant outlet temperatures of 500°C~1000°C. SCFs will be used as coolants (helium in GFRs and VHTRs; and SCW in SCWRs) and/or working fluids in power cycles (helium; mixture of nitrogen (80%) and helium [20%]; nitrogen, and carbon dioxide in Brayton gas-turbine cycles; and SCW “steam” in Rankine cycle).

Research on Thermal Efficiencies of Various Power Cycles for GFRs and VHTRs

2018 ◽  
Author(s):  
Mohammed Mahdi ◽  
Roman Popov ◽  
Igor Pioro
Keyword(s):  
Gas Turbine ◽  
Heavy Water ◽  
Nuclear Power ◽  
Power Plants ◽  
Supercritical Pressure ◽  
Combined Cycle ◽  
Power Cycles ◽  
Power Cycle ◽  
Combined Cycles ◽  
Gas Turbine Cycle

The vast majority of Nuclear Power Plants (NPPs) are equipped with water- and heavy-water-cooled reactors. Such NPPs have lower thermal efficiencies (30–36%) compared to those achieved at NPPs equipped with Advanced Gas-cooled Reactors (AGRs) (∼42%) and Sodium-cooled Fast Reactors (SFRs) (∼40%), and, especially, compared to those of modern advanced thermal power plants, such as combined cycle with thermal efficiencies up to 62% and supercritical-pressure coal-fired power plants — up to 55%. Therefore, NPPs with water- and heavy-water-cooled reactors are not very competitive with other power plants. Therefore, this deficiency of current water-cooled NPPs should be addressed in the next generation or Generation-IV nuclear-power reactors / NPPs. Very High Temperature Reactor (VHTR) concept / NPP is currently considered as the most efficient NPP of the next generation. Being a thermal-spectrum reactor, VHTR will use helium as a reactor coolant, which will be heated up to 1000°C. The use of a direct Brayton helium-turbine cycle was considered originally. However, technical challenges associated with the direct helium cycle have resulted in a change of the reference concept to indirect power cycle, which can be also a combined cycle. Along with the VHTR, Gas-cooled Fast Reactor (GFR) concept / NPP is also regarded as one of the most thermally efficient concept for the upcoming generation of NPPs. This concept was also originally thought to be with the direct helium power cycle. However, technical challenges have changed the initial idea of power cycle to a number of options including indirect Brayton cycle with He-N2 mixture, application of SuperCritical (SC)-CO2 cycles or combined cycles. The objective of the current paper is to provide the latest information on new developments in power cycles proposed for these two helium-cooled Generation-IV reactor concepts, which include indirect nitrogen-helium Brayton gas-turbine cycle, supercritical-pressure carbon-dioxide Brayton gas-turbine cycle, and combined cycles. Also, a comparison of basic thermophysical properties of helium with those of other reactor coolants, and with those of nitrogen, nitrogen-helium mixture and SC-CO2 is provided.

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.

Impact of Dry Cooler Air-Side Performance on a sCO2 Power Cycle for a CSP Application

2021 ◽  
Author(s):  
Kelsi M. Katcher ◽  
Dereje Amogne
Keyword(s):  
Heat Transfer ◽  
Large Scale ◽  
Heat Transfer Fluid ◽  
Outlet Temperature ◽  
Design Point ◽  
Power Cycle ◽  
Temperature Range ◽  
Design Performance ◽  
Power Block ◽  
Power Application

Abstract Uncertainty around the design and control of the supercritical CO2 power cycle must be reduced before this technology can be implemented for large-scale grid support. To better understand the day-to-day performance of an sCO2 cycle, off-design performance calculations must be included for all power block components, and performance assumptions must be removed. This study has expanded the modeled scope to include the air-side performance for the dry cooler and has incorporated discretized heat transfer calculations for both streams through the pre-cooler to better predict off-design performance. This study considered a recompression Brayton cycle in a concentrating solar power application. The cycle model utilized fixed sCO2 turbomachinery maps for the main compressor, recompressor, and expander operating to supply approximately 10 MW gross at the design point. Fixed vendor-supplied fan curves were used to calculate the air-side performance of the dry cooler. The primary heater was modeled considering both the sCO2 and heat transfer fluid streams. Off-design performance was predicted for an ambient temperature range of 0–55°C, a HTF temperature range of 705–735°C, and a HTF mass flow range of 50–105% of the design point value. To understand the importance of modeling the air-side performance, the cycle off-design performance was also calculated using a constant CO2 outlet temperature assumption and a constant approach temperature assumption for the dry cooler. Results show that using these assumptions can significantly alter the power output and cycle efficiency predictions.

Design of 1 MW Direct-Fired Combustor for an sCO2 Power Cycle

2021 ◽  
Author(s):  
Jacob Delimont ◽  
Steve White ◽  
Nathan Andrews
Keyword(s):  
Thermal Management ◽  
Fossil Fuels ◽  
Potential Method ◽  
Inlet Temperature ◽  
Power Cycles ◽  
Power Cycle ◽  
Southwest Research Institute ◽  
High Degree ◽  
Combustor Liner ◽  
Very High

Abstract Direct-fired super-critical carbon dioxide (sCO2) power cycles, are a potential method for efficiently capturing nearly all of the CO2 emissions from burning fossil fuels. Direct-fired sCO2 cycles require a very high degree of recuperation, which in turn means that the inlet temperature to the combustor is significantly higher than would typically be seen in a similar gas turbine combustors. Previous efforts have shown that combustor inlet temperatures of around 700 °C are to be expected for a cycle with around 1200 °C combustor exit temperatures [1]. This high inlet temperature means that bypass gasses are extremely hot, which poses some difficulties for the design of the combustion system, especially thermal management of the combustor liner and injectors in the 200 bar sCO2 environment. The project team led by Southwest Research Institute (SwRI) is in the process of building a 1 MW scale direct-fired combustor. This paper will detail some of the design challenges and obstacles associated with designing a direct-fired sCO2 combustor. These obstacles include thermal management of fuel and oxygen streams, oxygen safety, and combustor cooling. This paper will focus on many of the design questions necessary for the design of a direct-fired sCO2 combustor. This work presents computational modeling details of the actual 1 MW geometry currently being built.

Advanced S-CO2 Brayton Power Cycles in Nuclear and Fusion Energy

2019 ◽  
Author(s):  
Jan Syblik ◽  
Ladislav Vesely ◽  
Slavomir Entler ◽  
Vaclav Dostal ◽  
Jan Stepanek
Keyword(s):  
Power Plants ◽  
Cooling System ◽  
Initial Conditions ◽  
Fusion Energy ◽  
Systems Design ◽  
Thermodynamic Efficiency ◽  
Cooling Systems ◽  
Power Cycles ◽  
Power Cycle ◽  
Advantages And Disadvantages

Abstract Cooling system is one of the most important part of the power plants and cooling systems based on S-CO2 (Supercritical Carbon Dioxide) coolant seems nowadays perspective alternative to Helium and Rankine steam power cycles. Due to many advantages of S-CO2, these cooling systems are researched on many institutions and the results confirm that it should be successful for the future cooling systems design. One of the main objectives is comparison of the possible cooling mediums of DEMO2 (Demonstration power plant 2) with focusing on different power cycles with S-CO2. The First part of this article targets on comparison of three main coolants: steam, helium and S-CO2. The second part of this article focuses on the new software called CCOCS (Cooling Cycles Optimization Computational Software) which was developed on CTU in Prague. This software works on deeper optimization of the power cycles with various coolants and initial conditions. The third part describes advanced S-CO2 power cycles and enlarges past research, which was based on optimization of S-CO2 Brayton Simple power cycle and S-CO2 Re-compression power cycle both with recuperation and their usage in fusion and Fission energy engineering. It is possible to heighten thermodynamic efficiency of power cycle by changing the layout of the power cycle and the main objective of this paper is to compare four advanced layouts, describe the results of the optimization of these cycles and outline advantages and disadvantages of chosen optimized layouts.

Streamlining the Power Generation Profile of Concentrating Solar Power Plants

2018 ◽  
Author(s):  
Mohammad Abutayeh ◽  
Anas Alazzam ◽  
Bashar El-Khasawneh
Keyword(s):  
Heat Transfer ◽  
Power Generation ◽  
Power Plants ◽  
Solar Power ◽  
Heat Transfer Fluid ◽  
Concentrating Solar Power ◽  
Transfer Rates ◽  
Power Block ◽  
Solar Power Plants ◽  
Solar Field

A scheme to streamline the electric power generation profile of concentrating solar power plants of the parabolic trough collector type is suggested. The scheme seeks to even out heat transfer rates from the solar field to the power block by splitting the typical heat transfer fluid loop into two loops using an extra vessel and an extra pump. In the first loop, cold heat transfer fluid is pumped by the cold pump from the cold vessel to the solar field to collect heat before accumulating in the newly introduced hot vessel. In the second loop, hot heat transfer fluid is pumped by the hot pump from the hot vessel to a heat exchanger train to supply the power block with its heat load before accumulating in the cold vessel. The new scheme moderately decouples heat supply from heat sink allowing for more control of heat delivery rates thereby evening out power generation.

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