Transient Modeling of a Supercritical CO Power Cycle in GT ... · 2 Cycle CO 2 becomes...
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Transient Modeling of a Supercritical CO 2 Power Cycle in GT-SUITE and Comparison with Test Data Dr. Vamshi K. Avadhanula Dr. Timothy J. Held Systems Engineer Chief Technology Officer
Transcript of Transient Modeling of a Supercritical CO Power Cycle in GT ... · 2 Cycle CO 2 becomes...
Echogen Power Systems
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Transient Modeling of a Supercritical CO2 Power Cycle in GT-SUITE and Comparison with
Test DataDr. Vamshi K. Avadhanula Dr. Timothy J. Held
Systems Engineer Chief Technology Officer
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Synopsis for today’s discussion
1. Echogen Power Systems: Brief background2. Supercritical CO2 cycle3.Test system configuration4.Modeled system configuration5.Component validation6.Results discussion7.Summary
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Echogen Background
2007 Echogen founded
2011 Partnership with Dresser-Rand for oil & gas market; development of EPS100 7.5 MW engine begins
2013 Partnership with GE Marine;development of EPS30 1.35 MW engine begins
2014 EPS100 completes factory testing
2016 EPS30 testing commences with high-speed alternator subsystem test
2017 Pursuing commercial pilot sites for all EPS products
Plans for the future…
• Introduce additional EPS engine sizes
• Progress to primary power & combined cycle
• Industrial and nuclear applications
Echogen Power Systems is the industry leader in development of supercritical CO2 heat recovery systems.
Founded in 2007, EPS has progressed from small multi-kW demonstration units to the recent multi-MW heat recovery package, the EPS100.
Akron, OH
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The Echogen supercritical CO2 Cycle
CO2 becomes supercritical above 31oC, 74 bar, and has properties of both liquid and gas. There is no distinct phase change when moving in/out of supercritical region.
1. Liquid CO2 pumped to supercritical state
2. CO2 preheated at recuperator
3. Recovered waste heat added at waste heat exchanger
4. High energy CO2 expanded at turbine drives generator
5. Expanded CO2 is pre-cooled at recuperator
6. CO2 is condensed to a liquid at condenser
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Test System: 7.3MWe net power sCO2 cycle (EPS100)
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GT-SUITE System Model
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Simulink Control System Model
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Reason for sCO2 Cycle Model in GT-SUITE
• Determining the control system strategies before installing the system at customer site.
• Rockwell Automation/Allen Bradley (AB) control system was used in test system
• Future integration of AB control system with GT-SUITE using Simulink (or) FMI
• Currently: GT-SUITE for system model with Simulink control integration
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Heat exchanger submodeling
▪ Counterflow model based on Plate & Frame heat exchanger template
▪ Inlet temperatures, pressures and flows are imposed boundary conditions
▪ Heat transferred (hot and cold sides independently) and hot/cold side pressure drops are outputs
▪ HTC and dP models include calibration to selected steady-state data points
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Heat exchanger submodeling
Recuperator and HRHX outlet temperatures from validation simulation
Recuperator and HRHX pressure drops from validation simulation
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Turbomachinery: Turbines and Compressor Models
▪ Turbine maps: Two-dimensional tables for corrected mass flow rate and isentropic efficiency in terms of corrected speed and isentropic enthalpy change.
▪ wc = fw(Nc, dhsc)▪ ηs = fη(Nc, dhsc)▪ Nc = fN(N, γ, Z, T)▪ dhsc = fdh(dhsa, γ, Z, p)▪ wc = f2(w, γ, Z, T, p)
▪ Compressor maps: Two-dimensional tables, with flow coefficient and inlet fluid temperature as the primary correlating variables.
▪ ηp = fηp(Φ, T)▪ Ψ = fΨ(Φ, T)
▪ Fortran models were developed and are being used for turbomachinery
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Valves and Control System Model
▪ Control valves are simulated as lift valves
▪ Submodel simulation is conducted, where the throttle valve position was changed in stepwise manner and the power turbine speed response was noted.
▪ Assuming first order linear behavior of the valve, the optimal proportional and integral gains for the control loop were determined.
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Model Boundary ConditionsCold water flowrate (kg/s) Cold water temperature (oC)
PHX CO2 temperature (oC) Generator Load (kW)
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Model Control System Boundary Conditions
• Turbocompressor speed @ 29500RPM using PCV2 valve
• Power turbine speed control from initial spin to synchronous speed (24841RPM) using TCV3 and FCV41 valves
• System low pressure control using Accumulator and BV39 valve (open/close valve)
• Turbocompressor bearing drain pressure is controlled using PCV11 valve
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Results: Turbocompressor Speed and Compressor Pressures
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Results: Valve Positions
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Results: Temperatures and Pressure Drops
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Results: HRHX Temperatures and HTR
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Results: Turbomachinery Performance
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Summary:▪ sCO2 power cycle was modeled and simulated in GT-SUITE system simulation
software.▪ Individual system components were modeled and validated.▪ Transient simulation of full system model was carried out with boundary
conditions supplied from test data.▪ Good agreement between transient simulation results and test data was
observed.Future Work:▪ Integration of AB control system and GT-SUITE system model▪ Thermal lag behavior of heat exchangers is also been studied.▪ For future work will include system modeling from initial startup to full load
operation.For detailed report please refer to:
Avadhanula, V.K., and Held, T.J., “Transient Modeling of a Supercritical CO2 Power Cycle and Comparison with Test Data”, Proceedings of ASME Turbo Expo 2017, June 26-30, 2017, Charlotte, NC. Paper # GT2017-63279
Thank you….
