scholarly journals Steady State Supercritical Carbon Dioxide Recompression Closed Brayton Cycle Operating Point Comparison With Predictions

2014 ◽  
Author(s):  
Jim Pasch ◽  
Tom Conboy ◽  
Darryn Fleming ◽  
Matt Carlson ◽  
Gary Rochau
Keyword(s):  
Carbon Dioxide ◽  
Steady State ◽  
Supercritical Carbon Dioxide ◽  
Computer Model ◽  
Model Verification ◽  
Operating Point ◽  
Brayton Cycle ◽  
Assembly Design ◽  
Test Assembly ◽  
Supercritical Carbon

The U.S. Department of Energy Office of Nuclear Energy (DOE-NE) supercritical carbon dioxide recompression closed Brayton cycle (RCBC) test assembly (TA) construction has been completed to its original design and resides at Sandia National Laboratories, New Mexico. Commissioning tests were completed in July 2012, followed by a number of tests in both the recompression CBC configuration, and in a bottoming cycle configuration that is proprietary to a current customer. While the test assembly has been developed and installed to support testing, a computer model of the loop, written in Fortran programming language, has also been developed. The purpose of this iterative model is to facilitate data interpretation, guide test assembly design modifications, develop control schemes, and serve as a foundation from which to develop a transient model. Of central utility is its modular nature, which has already been leveraged to develop a customer’s bottoming cycle configuration. Verification that the model uses appropriate physical representations of components and processes, is performing as intended, and validation that the model accurately reproduces test data, are necessary activities. Completion of the model’s verification and validation (V&V) supports the long-term goal of commercializing the RCBC for a sodium fast reactor. This paper presents verification results of certain subprocesses of the iterative computer model. Verification of these subprocesses was completed with positive results. While an adequate range of data for complete and thorough validation do not yet exist, comparison of subprocess predictions with data from a single, representative operating point are presented as are explanations for differences. Recommendations for activities necessary to complete subprocess and model validation are given. The RCBC iterative computer model V&V process should be revisited following completion of these recommended actions and the generation of steady state data while operating near the test assembly design point.

Steady-State Power Operation of a Supercritical Carbon Dioxide Brayton Cycle With Thermal-Hydraulic Control

2016 ◽  
Author(s):  
Eric M. Clementoni ◽  
Timothy L. Cox ◽  
Martha A. King
Keyword(s):  
Carbon Dioxide ◽  
Steady State ◽  
Supercritical Carbon Dioxide ◽  
Integrated System ◽  
Working Fluid ◽  
Stable Steady State ◽  
Brayton Cycle ◽  
Hydraulic Control ◽  
Wide Range ◽  
Supercritical Carbon

The Bechtel Marine Propulsion Corporation (BMPC) Integrated System Test (IST) is a two shaft recuperated closed Brayton cycle using supercritical carbon dioxide (sCO2) as the working fluid. The IST is a simple recuperated Brayton cycle with a variable speed turbine driven compressor and a constant speed turbine driven generator designed to output 100 kWe. The main focus of the IST is to demonstrate operational, control, and performance characteristics of an sCO2 Brayton power cycle over a wide range of conditions. IST operation has reached the point where the system can be run with the turbine-compressor thermal-hydraulically balanced so that the net power of the cycle is equal to the turbine-generator output. In this operating mode, power level is changed by using the compressor recirculation valve to adjust the fraction of compressor flow that goes to the turbines as well as the compressor pressure ratio. Steady-state operational data and trends are presented at various system power levels from near zero net cycle power to maximum operating power using a simplified thermal-hydraulic based control method. Confirmation of stable steady-state operation of the system with automatic thermal-hydraulic control is also discussed.

Steady-State Power Operation of a Supercritical Carbon Dioxide Brayton Cycle

2014 ◽  
Author(s):  
Eric M. Clementoni ◽  
Timothy L. Cox
Keyword(s):  
Carbon Dioxide ◽  
Steady State ◽  
Supercritical Carbon Dioxide ◽  
Power Level ◽  
Operating Mode ◽  
Integrated System ◽  
Working Fluid ◽  
Brayton Cycle ◽  
Wide Range ◽  
Supercritical Carbon

Bechtel Marine Propulsion Corporation (BMPC) is testing a supercritical carbon dioxide (S-CO2) Brayton system at the Bettis Atomic Power Laboratory. The Integrated System Test (IST) is a two shaft recuperated closed Brayton cycle with a variable speed turbine driven compressor and a constant speed turbine driven generator using S-CO2 as the working fluid designed to output 100 kWe. The main focus of the IST is to demonstrate operational, control and performance characteristics of an S-CO2 Brayton power cycle over a wide range of conditions. IST operation has reached the point where the system can be operated with the turbine-compressor thermal-hydraulically balanced so that the net output of the system is equal to the turbine-generator output. In this operating mode, power level is changed by using the compressor recirculation valve which changes the fraction of compressor flow that goes to the turbines. Steady-state operation with the turbine-compressor thermal hydraulically balanced at near zero net system power is presented.

Numerical Simulation of the Performance of an Axial Compressor Operating With Supercritical Carbon Dioxide

2018 ◽  
Author(s):  
Jinlan Gou ◽  
Wei Wang ◽  
Can Ma ◽  
Yong Li ◽  
Yuansheng Lin ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Numerical Simulation ◽  
Supercritical Carbon Dioxide ◽  
Critical Point ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Axial Compressor ◽  
Brayton Cycle ◽  
Supercritical Carbon

Using supercritical carbon dioxide (SCO2) as the working fluid of a closed Brayton cycle gas turbine is widely recognized nowadays, because of its compact layout and high efficiency for modest turbine inlet temperature. It is an attractive option for geothermal, nuclear and solar energy conversion. Compressor is one of the key components for the supercritical carbon dioxide Brayton cycle. With established or developing small power supercritical carbon dioxide test loop, centrifugal compressor with small mass flow rate is mainly investigated and manufactured in the literature; however, nuclear energy conversion contains more power, and axial compressor is preferred to provide SCO2 compression with larger mass flow rate which is less studied in the literature. The performance of the axial supercritical carbon dioxide compressor is investigated in the current work. An axial supercritical carbon dioxide compressor with mass flow rate of 1000kg/s is designed. The thermodynamic region of the carbon dioxide is slightly above the vapor-liquid critical point with inlet total temperature 310K and total pressure 9MPa. Numerical simulation is then conducted to assess this axial compressor with look-up table adopted to handle the nonlinear variation property of supercritical carbon dioxide near the critical point. The results show that the performance of the design point of the designed axial compressor matches the primary target. Small corner separation occurs near the hub, and the flow motion of the tip leakage fluid is similar with the well-studied air compressor. Violent property variation near the critical point creates troubles for convergence near the stall condition, and the stall mechanism predictions are more difficult for the axial supercritical carbon dioxide compressor.

scholarly journals Advanced Supercritical Carbon Dioxide Brayton Cycle Development

2015 ◽  
Author(s):  
Mark Anderson ◽  
James Sienicki ◽  
Anton Moisseytsev ◽  
Gregory Nellis ◽  
Sanford Klein
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Brayton Cycle ◽  
Supercritical Carbon

Supercritical Carbon Dioxide Heat Transfer in Horizontal Semicircular Channels

2012 ◽  
Vol 134 (8) ◽  
Author(s):  
Alan Kruizenga ◽  
Hongzhi Li ◽  
Mark Anderson ◽  
Michael Corradini
Keyword(s):  
Heat Transfer ◽  
Carbon Dioxide ◽  
Heat Exchanger ◽  
Supercritical Carbon Dioxide ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Brayton Cycle ◽  
Heat Exchanger Design ◽  
Transfer Behavior ◽  
Supercritical Carbon

Competitive cycles must have a minimal initial cost and be inherently efficient. Currently, the supercritical carbon dioxide (S-CO2) Brayton cycle is under consideration for these very reasons. This paper examines one major challenge of the S-CO2 Brayton cycle: the complexity of heat exchanger design due to the vast change in thermophysical properties near a fluid’s critical point. Turbulent heat transfer experiments using carbon dioxide, with Reynolds numbers up to 100 K, were performed at pressures of 7.5–10.1 MPa, at temperatures spanning the pseudocritical temperature. The geometry employed nine semicircular, parallel channels to aide in the understanding of current printed circuit heat exchanger designs. Computational fluid dynamics was performed using FLUENT and compared to the experimental results. Existing correlations were compared, and predicted the data within 20% for pressures of 8.1 MPa and 10.2 MPa. However, near the critical pressure and temperature, heat transfer correlations tended to over predict the heat transfer behavior. It was found that FLUENT gave the best prediction of heat transfer results, provided meshing was at a y+ ∼ 1.

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