Bechtel Marine Propulsion Corporation Bettis Atomic Power Laboratory West Mifflin, PA Sensitivity of an Operating Supercritical Carbon Dioxide Brayton Cycle to Compressor and Turbine Inlet Temperature Eric Clementoni Page 1
Presentation Summary sco 2 Brayton Cycle Integrated Systems Test (IST) Overview Compressor Inlet Temperature Sensitivity System Control Test Results Turbine Inlet Temperature Sensitivity System Control Test Results Page 2
100 kweist has been main sco 2 development focus of BMPC Simple Braytoncycle Single variable speed turbine-compressor Single constant speed turbine-generator Single recuperator Focus on system control Rapid startup Power changes Shutdown IST Overview Heat Source Generator Turbine Turbine Recuperator Compressor Page 3 Sea Water Cooling Water Precooler
IST Physical Layout Hot Oil System Turbine Throttle Valves Turbo-Compressor Compressor Recirculation Valve Recuperator Turbo-Generator Precooler Leakage Collection Compressors Page 4
IST Physical Layout Turbo-Generator Turbo-Compressor(not visible) Recuperator Precooler Page 5
IST Turbomachinery Turbo-Generator Thrust Bearing Turbo-Compressor Compressor/Diffuser Turbine Page 6
Normal Thermal-Hydraulic Control IHX Gen Load regulated to maintain 60,000 rpm shaft speed Mot/ Gen T T C No load TC speed setpoint function of TG load setpoint PI control regulates TC shaft speed Precooler Recuperator Page 7
IST Efficiency vs. Power 8.0% 7.0% 6.0% Cycle Efficiency 5.0% 4.0% 3.0% 2.0% 1.0% 0.0% 0 5 10 15 20 25 30 35 40 45 Output Power (kw) Page 8
Compressor Inlet Temperature Sensitivity Overview System mass held constant, compressor inlet pressure varies based on system conditions Heater power automatically controlled to maintain CO 2 outlet temperature of 440 F IHX Gen Load regulated to maintain 60,000 rpm shaft speed Mot/ Gen T T C No load Recuperator TC speed setpoint fixed at 48,670 rpm PI control maintains TC shaft speed at setpoint Precooler Chilled water flow automatically controlled to obtain desired compressor inlet temperature Range: 90-102 F Page 9
Compressor Inlet Conditions 2000 44.5 1800 44 1600 43.5 1400 43 Pressure (psia) 1200 1000 800 42.5 42 41.5 Density (lbm/ft 3 ) 600 41 400 200 0 40.5 Compressor Inlet Pressure Normal IST operating Compressor Outlet Pressure conditions 40 Compressor Inlet Density 39.5 90 92 94 96 98 100 102 104 Compressor Inlet Temperature (F) Page 10
Compressor Flow & Brayton Power 30 Compressor Flow (lbm/s) or Brayton Output Power (kw) 25 20 15 10 5 0 Brayton Output Power Compressor Flow 90 92 94 96 98 100 102 104 Compressor Inlet Temperature (F) Page 11
Cycle Efficiency 5.6% 5.5% Brayton Cycle Efficiency 5.4% 5.3% 5.2% 5.1% 5.0% 90 92 94 96 98 100 102 104 Compressor Inlet Temperature (F) Page 12
Cycle Efficiency 8.0% 7.0% 6.0% Cycle Efficiency 5.0% 4.0% 3.0% 2.0% 1.0% 0.0% 0 5 10 15 20 25 30 35 40 45 Output Power (kw) Page 13
Cycle Efficiency 8.0% 7.0% 6.0% Cycle Efficiency 5.0% 4.0% 3.0% 103 F 91 F 2.0% 1.0% 0.0% 0 5 10 15 20 25 30 35 40 45 Output Power (kw) Page 14
Turbine Inlet Temperature Sensitivity Overview System mass held constant, compressor inlet pressure varies based on system conditions Heater power automatically controlled to maintain CO 2 outlet temperature Range: 390-440 F IHX Gen Load regulated to maintain 60,000 rpm shaft speed Mot/ Gen T T C No load TC speed varies with turbine inlet temperature Valve position fixed at 36% open Precooler Chilled water flow automatically controlled to obtain desired compressor inlet temperature of 96 F Recuperator Page 15
Power and Compressor Speed 30 52000 25 50000 Brayton Output Power (kw) 20 15 10 48000 46000 44000 Compressor Speed (rpm) 5 42000 Brayton Output Power Compressor Speed 0 40000 380 390 400 410 420 430 440 450 Turbine Inlet Temperature (F) Page 16
Cycle Efficiency 7.0% 6.0% 5.0% Brayton Cycle Efficiency 4.0% 3.0% 2.0% 1.0% 0.0% 380 390 400 410 420 430 440 450 Turbine Inlet Temperature (F) Page 17
Cycle Efficiency 8.0% 7.0% 6.0% 440 F Cycle Efficiency 5.0% 4.0% 3.0% 2.0% 1.0% 390 F 0.0% 0 5 10 15 20 25 30 35 40 45 Output Power (kw) Page 18
Summary IST response to varying compressor and turbine inlet temperatures consistent with most expectations Cycle efficiency benefit from reducing compressor inlet temperature diminished in a fixed mass system Cycle efficiency vs. output power appears to not be strongly influenced by turbine inlet temperature Page 19
Acknowledgements This presentation summarizes work that has been performed a number of devoted engineers, scientists, technicians, and support personnel at the Bechtel Marine Propulsion Corporation and our subcontractors. This paper would not be possible without the efforts of this team. Page 20