Investigation of Bypass Valve Positions on Performance of Closed Brayton Cycle

2016 ◽  
Author(s):  
Xiao Li ◽  
Xiaoyong Yang ◽  
Youjie Zhang
Keyword(s):  
Integrated System ◽  
Engineering Practice ◽  
Brayton Cycle ◽  
Algebraic Equations ◽  
Bypass Valve ◽  
Power Regulation ◽  
Final Design ◽  
Heat Recuperation ◽  
Model Compressor ◽  
Point Kinetics

HTR-10GT is a closed Brayton cycle with two-stage compression and heat recuperation. Bypass control was adopted for rapid power regulation and safety protection. A bypass valve could be set between any two positions at different pressure levels, there would be in total 21 setting possibilities, whose regulating behaviors remained to be fully clarified. The dynamic characteristics of these settings were thus analyzed by implementing numerical simulation on the integrated system model. The reactor was modeled with point-kinetics and 1D thermal-hydraulics model; compressor performance calculation was based on digitization of the performance map and Reynolds number correlation; Flügel formula was chosen to calculate turbine performance. The system was modeled with Modelica, and the DASSL code was used to solve the Differential and Algebraic Equations. The results showed that only 6 choices among the 21 remained acceptable for engineering practice. The degree and rate on power output reduction, anti-surge effect and long-term thermal effects at reactor inlet and along recuperator’s metal wall were evaluated and compared among these choices to give out proposals. This research clarified the characteristics of bypass valves at different positions to give a reference on the final design of the control methods, and proposed a combination of valves for multi-valve cooperative regulation.

scholarly journals HTR-10GT Dual Bypass Valve Control Features and Decoupling Strategy for Power Regulation

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Xiao Li ◽  
Xiaoyong Yang ◽  
Youjie Zhang ◽  
Jie Wang
Keyword(s):  
Control Method ◽  
Brayton Cycle ◽  
Algebraic Equations ◽  
Control Effect ◽  
Future Design ◽  
Linear Control Theory ◽  
Bypass Valve ◽  
Power Regulation ◽  
Heat Recuperation ◽  
Valve Control

HTR-10GT is the development of HTR-10 reactor, which PCU will be a closed Brayton cycle with two-stage compression and heat recuperation. Bypass control method is adopted for rapid power regulation and safety protection. But quick opening of single bypass valve would inevitably lead to temperature shocks in multiple components especially at the reactor inlet and the recuperator core. Based on the regulating characteristics of each possible bypass valve, a dual bypass valve control scheme was proposed along with MIMO decoupling controller designed with diagonal matrix method. The system was modeled with Modelica; the DASSL code was used to solve the Differential and Algebraic Equations during simulations. System’s control characteristic was analyzed with classical linear control theory and H∞ theory applied on linearized system model. Further numerical simulations showed that cooperative functioning of two bypass valves could effectively limit the temperature variation during power regulation, while the decoupler could improve the control effect and the stability of the system. The results will be helpful for the future design of the control system of HTR-10GT or other closed Brayton cycle of the same kind.

scholarly journals Development and Verification of a Transient Analysis Tool for Reactor System Using Supercritical CO2 Brayton Cycle as Power Conversion System

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Pan Wu ◽  
Chuntian Gao ◽  
Jianqiang Shan
Keyword(s):  
Nuclear Power ◽  
Transient Analysis ◽  
Friction Model ◽  
Integrated System ◽  
Transfer Model ◽  
Analysis Tool ◽  
Brayton Cycle ◽  
Conduction Model ◽  
Comparison Results ◽  
Conversion System

Supercritical CO2 Brayton cycle is a good choice of thermal-to-electric energy conversion system, which owns a high cycle efficiency and a compact cycle configuration. It can be used in many power-generation applications, such as nuclear power, concentrated solar thermal, fossil fuel boilers, and shipboard propulsion system. Transient analysis code for Supercritical CO2 Brayton cycle is a necessity in the areas of transient analyses, control strategy study, and accident analyses. In this paper, a transient analysis code SCTRAN/CO2 is developed for Supercritical CO2 Brayton Loop based on a homogenous model. Heat conduction model, point neutron power model (which is developed for nuclear power application), turbomachinery model for gas turbine, compressor and shaft model, and PCHE type recuperator model are all included in this transient analysis code. The initial verifications were performed for components and constitutive models like heat transfer model, friction model, and compressor model. The verification of integrated system transient was also conducted through making comparison with experiment data of SCO2EP of KAIST. The comparison results show that SCTRAN/CO2 owns the ability to simulate transient process for S-CO2 Brayton cycle. SCTRAN/CO2 will become an important tool for further study of Supercritical CO2 Bryton cycle-based nuclear reactor concepts.

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.

scholarly journals A Crush Zone Design for an Existing Passenger Rail Cab Car

2005 ◽  
Author(s):  
Eloy Martinez ◽  
David Tyrell ◽  
Robert Rancatore ◽  
Richard Stringfellow ◽  
Gabriel Amar
Keyword(s):  
Primary Energy ◽  
Integrated System ◽  
Interface Interaction ◽  
Finite Element Software ◽  
Passenger Rail ◽  
Final Design ◽  
Energy Absorbers ◽  
Long Stroke ◽  
To Receive ◽  
Crush Zone

A Crash Energy Management (CEM) cab car crush zone design has been developed for retrofit onto an existing Budd M1 cab car. This design is to be used in the upcoming full-scale train-to-train test of a CEM consist impacting a standing freight consist of comparable weight. The cab car crush zone design is based upon the coach car crush zone design that has been previously developed and tested. The integrated system was developed after existing national and international CEM systems were reviewed. A detailed set of design requirements was then drafted, and preliminary designs of sub-assemblies were developed. The preliminary designs were analyzed using detailed large deformation finite element software. Performance of the cab car crush zone under ideal and non-ideal loading conditions was analyzed prior to development of the final design. The key components of the design include: a long stroke push-back coupler capable of accommodating the colliding locomotive coupler, a deformable anti-climber to manage the colliding interface interaction, an integrated end frame on which the deformable anti-climber is attached, a set of primary energy absorbers designed to crush in a controlled manner while absorbing the majority of the collision energy, and a survivable space for the operator which pushes back into an electrical closet. The cab car crush zone is designed to control both lateral and vertical vehicle motions that can promote lateral buckling of the train and override of the impacting equipment. The design is capable of managing the colliding interface interaction with a freight locomotive and passing crush back to successive crush zones. Detailed fabrication drawings have been developed and submitted to a fabrication shop. In addition, existing Budd M1 cars are being prepared to receive the retrofit components.

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.

Sign in / Sign up

Export Citation Format

Share Document