Response of a Compact Recuperator to Thermal Transients in a Supercritical Carbon Dioxide Brayton Cycle

2017 ◽  
Author(s):  
Eric M. Clementoni ◽  
Timothy L. Cox ◽  
Martha A. King
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Heat Exchangers ◽  
High Surface ◽  
Integrated System ◽  
Compact Heat Exchangers ◽  
Power Cycle ◽  
Thermal Transients ◽  
Wide Range ◽  
Supercritical Carbon

Supercritical carbon dioxide (sCO2) power cycle designs are typically highly recuperated, transferring heat from the high temperature turbine exhaust stream to the compressor discharge stream thereby increasing overall cycle efficiency. Compact heat exchangers are preferred for this application due to their high surface area-to-volume ratio enabling much smaller heat exchangers as compared to conventional designs. However, compact heat exchangers have a higher metal density than conventional heat exchangers which could result in thermal lag during rapid temperature transients. The Naval Nuclear Laboratory has been operating the Integrated System Test (IST) with the objective of demonstrating the ability to operate and control an sCO2 Brayton power cycle over a wide range of conditions. Rapid turbomachinery startups and power transients result in thermal transients on the recuperator. This paper presents thermal transients observed in the IST recuperator during loop startup and power transients and illustrates the time to achieve thermal equilibrium following the transients.

Supercritical Carbon Dioxide Brayton Power Cycle Development Overview

2012 ◽  
Author(s):  
Kenneth J. Kimball ◽  
Eric M. Clementoni
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Performance Model ◽  
Integrated System ◽  
Working Fluid ◽  
Power Cycle ◽  
Test Loop ◽  
Wide Range ◽  
Atomic Power Laboratory ◽  
Supercritical Carbon

The Knolls Atomic Power Laboratory (KAPL) and Bettis Atomic Power Laboratory are testing a supercritical carbon dioxide (S-CO2) Brayton power cycle system. The 100 kWe 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. The IST was designed to demonstrate operational, control and performance characteristics of an S-CO2 Brayton power cycle over a wide range of conditions. The IST design includes a comprehensive instrumentation and control system incorporating results of turbomachinery operational testing performed at Barber Nichols Inc (BNI) in the Sandia National Laboratory’s DOE test loop. A detailed dynamic performance model was used both to predict IST performance and to evaluate the testing completed at BNI. The IST construction was completed in mid 2011 and is currently undergoing shakedown testing. Results of testing completed to date and future testing plans will be summarized.

Off-Nominal Component Performance in a Supercritical Carbon Dioxide Brayton Cycle

2015 ◽  
Author(s):  
Eric M. Clementoni ◽  
Timothy L. Cox ◽  
Martha A. King
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Integrated System ◽  
Design System ◽  
Working Fluid ◽  
Brayton Cycle ◽  
Wide Range ◽  
Primary Driver ◽  
Atomic Power Laboratory ◽  
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 simple 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. Therefore, the IST was designed to operate in a configuration and at conditions that support demonstrating the controllability of the closed S-CO2 Brayton cycle. Operating at high system efficiency and meeting a specified efficiency target are not requirements of the IST. However, efficiency is a primary driver for many commercial applications of S-CO2 power cycles. This paper uses operational data to evaluate component off-nominal performance and predict that design system operation would be achievable.

Startup and Operation of a Supercritical Carbon Dioxide Brayton Cycle

2014 ◽  
Vol 136 (7) ◽  
Author(s):  
Eric M. Clementoni ◽  
Timothy L. Cox ◽  
Christopher P. Sprague
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Operating Temperature ◽  
Integrated System ◽  
Working Fluid ◽  
Brayton Cycle ◽  
Normal Operating ◽  
Wide Range ◽  
Startup Process ◽  
Supercritical Carbon

Bechtel Marine Propulsion Corporation (BMPC) is testing a supercritical carbon dioxide (S-CO2) Brayton system at the Bettis Atomic Power Laboratory. The 100 kWe 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. The IST was designed to demonstrate operational, control, and performance characteristics of an S-CO2 Brayton power cycle over a wide range of conditions. Initial operation of the IST has proven a reliable method for startup of the Brayton loop and heatup to normal operating temperature (570 °F). An overview of the startup process, including initial loop fill and charging, and heatup to normal operating temperature is presented. Additionally, aspects of the IST startup process which are related to the loop size and component design which may be different for larger systems are discussed.

Startup and Operation of a Supercritical Carbon Dioxide Brayton Cycle

2013 ◽  
Author(s):  
Eric M. Clementoni ◽  
Timothy L. Cox ◽  
Christopher P. Sprague
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Operating Temperature ◽  
Integrated System ◽  
Working Fluid ◽  
Brayton Cycle ◽  
Normal Operating ◽  
Wide Range ◽  
Startup Process ◽  
Supercritical Carbon

Bechtel Marine Propulsion Corporation (BMPC) is testing a supercritical carbon dioxide (S-CO2) Brayton system at the Bettis Atomic Power Laboratory. The 100 kWe 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. The IST was designed to demonstrate operational, control and performance characteristics of an S-CO2 Brayton power cycle over a wide range of conditions. Initial operation of the IST has proven a reliable method for startup of the Brayton loop and heatup to normal operating temperature (570°F). An overview of the startup process, including initial loop fill and charging, and heatup to normal operating temperature is presented. Additionally, aspects of the IST startup process which are related to the loop size and component design which may be different for larger systems are discussed.

Off-Nominal Component Performance in a Supercritical Carbon Dioxide Brayton Cycle

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Eric M. Clementoni ◽  
Timothy L. Cox ◽  
Martha A. King
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Integrated System ◽  
Design System ◽  
Working Fluid ◽  
Brayton Cycle ◽  
Wide Range ◽  
Primary Driver ◽  
Atomic Power Laboratory ◽  
Supercritical Carbon

Bechtel Marine Propulsion Corporation (BMPC) is testing a supercritical carbon dioxide (sCO2) Brayton system at the Bettis Atomic Power Laboratory. The integrated system test (IST) is a simple recuperated closed Brayton cycle with a variable-speed turbine-driven compressor and a constant-speed turbine-driven generator using sCO2 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 sCO2 Brayton power cycle over a wide range of conditions. Therefore, the IST was designed to operate in a configuration and at conditions that support demonstrating the controllability of the closed sCO2 Brayton cycle. Operating at high system efficiency and meeting a specified efficiency target are not requirements of the IST. However, efficiency is a primary driver for many commercial applications of sCO2 power cycles. This paper uses operational data to evaluate component off-nominal performance and predict that design system operation would be achievable.

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.

Transient Power Operation of a Supercritical Carbon Dioxide Brayton Cycle

2017 ◽  
Author(s):  
Eric M. Clementoni ◽  
Timothy L. Cox ◽  
Martha A. King ◽  
Kevin D. Rahner
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Control Strategy ◽  
Power Level ◽  
Integrated System ◽  
Operating Conditions ◽  
System Response ◽  
Brayton Cycle ◽  
Wide Range ◽  
Supercritical Carbon

The Naval Nuclear Laboratory has been operating the Integrated System Test (IST) with the objective of demonstrating the ability to operate and control a supercritical carbon dioxide (sCO2) Brayton power cycle over a wide range of conditions. The IST is a two shaft recuperated closed sCO2 Brayton cycle with a variable speed turbine-driven compressor and a constant speed turbine-driven generator designed to output 100 kWe. This paper presents a thermal-hydraulic lead control strategy for operation of the cycle over a range of operating conditions along with predicted and actual IST system response to power level changes using this control strategy.

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.

Supercritical Carbon Dioxide Brayton Cycle Development Overview

2013 ◽  
Author(s):  
Kenneth J. Kimball ◽  
Kevin D. Rahner ◽  
Joseph P. Nehrbauer ◽  
Eric M. Clementoni
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Dynamic Performance ◽  
Test Procedure ◽  
Performance Model ◽  
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 100 kWe 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. The IST was designed to demonstrate operational, control and performance characteristics of an S-CO2 Brayton power cycle over a wide range of conditions. The IST design includes a comprehensive instrumentation and control system to facilitate precise control of loop operations and to allow detailed evaluation of component and system performance. A detailed dynamic performance model is being used to predict IST performance, support test procedure development and to evaluate test results. An overview of IST testing progress and plans is provided. Testing in the IST was initiated in 2012. Initial test operations included successful system startup, initial transition to electrical power generation and increased power operations using independent speed control of the turbomachinery. Results of testing completed to date and future testing plans will be summarized.

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