1 / 29

Stirling Engine System for Solar Thermal Generation and Energy Storage

Stirling Engine System for Solar Thermal Generation and Energy Storage. LoCal Retreat, June 8-9 2009. Outline. Overview/Motivation System Description Early Prototypes Higher Power Engine Design. Thermal Energy Applications. Solar Thermal Dispatchable Generation

Download Presentation

Stirling Engine System for Solar Thermal Generation and Energy Storage

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Stirling Engine System for Solar Thermal Generation and Energy Storage LoCal Retreat, June 8-9 2009

  2. Outline • Overview/Motivation • System Description • Early Prototypes • Higher Power Engine Design

  3. Thermal Energy Applications • Solar Thermal • Dispatchable Generation • Low cost, simple manufacturing • Thermal Storage • Dispatchable Resource • Low capital cost • Waste Heat Recovery • Free energy source – Industrial Processes, Combined Cycle • Low Temperature

  4. Renewable Energy Challenges Renewable Energy Challenges Solar Thermal Advantages • Cost • Intermittency • Production bottlenecks • Lower Cost • Inherent Storage • Simple Manufacturing • Versatility

  5. Intermittency and Energy Storage 1.5 MW Wind Turbine 4.6 MW Solar Installation Source: J. Apt, A. Curtright, “The Spectrum of Power from Utility-Scale Wind Farms and Solar Photovoltaic Arrays”, CEIC 2008

  6. Cost Comparison Solar Thermal Photovoltaic Source: PV data from Solarbuzz

  7. Solar System Schematic

  8. Stirling Engine • Can achieve large fraction (60-70%) of Carnot efficiency • Low cost, simple components • Fuel Flexible • Reversible • Scalable engine and storage capacity

  9. Stirling Cycle Overview 4 1 2 3

  10. Research • Designed, built, tested two low power prototypes • Single phase and multiphase machines • Low power • Verified engineering models • Design of high power prototype • Improved simulation and design • Heat exchanger design • Optimization of geometry, parameters

  11. Prototype 1: Single Phase

  12. Gamma-Type Free-Piston Stirling • Temperatures: Th=175 oC, Tk=25 oC • Working fluid: Air @ ambient pressure • Frequency: 3 Hz • Pistons • Stroke: 15 cm • Diameter: 10 cm • Indicated power: • Schmidt analysis 75 W (thermal input) - 25 W (mechanical output) • Adiabatic model 254 W (thermal input) - 24 W (mechanical output) Displacer Power piston

  13. Prototype Operation

  14. Piston Systems

  15. Prototype 2: Multi-phase

  16. Components

  17. Experimental Data

  18. Gas Compression Loss

  19. Reverser More Phases => Less Compression

  20. High Power Design

  21. Energy Flows and Losses Regenerator Ineffectiveness Heat Transfer Leakages Ideal Stirling Cycle Heat In Heater Cooler Rejected Heat Heater and ½ Regenerator Flow Loss Cooler and ½ Regenerator Flow Loss Internal Bearing & Motion Losses PV Work Out Alternator Inefficiency, Bearing Losses Gas Hysteresis Loss Electrical Output

  22. Differences from prototypes • Design Improvements • Improved heat exchanger design • Refined simulation and models • Extensive optimization • Scaling • Increased pressure • Increased frequency • Increased volume • Relatively smaller losses

  23. Efficiency and Power Output Contour Plot 20Hz, 25bar Air

  24. What’s Next? • Finalize designs • Fabrication and testing of high power prototype • Design/experimental work with thermal storage • Explore waste heat electric generation • Economic analysis of cogen, energy storage opportunities

  25. Residential Example • 30-50 sqm collector => 3-5 kWe peak at 10%eff • Reject 12-20 kW thermal power at peak. Much larger than normal residential hot water systems – would provide year round hot water, and perhaps space heating • Hot side thermal storage can use insulated (pressurized) hot water storage tank. Enables 24 hr electric generation on demand. • Another mode: heat engine is bilateral – can store energy when low cost electricity is available

  26. Thermal Storage Example • Sealed, insulated water tank • Cycle between 150 C and 200 C • Thermal energy density of about 60 W-hr/kg, 60 W-hr/liter • Considering Carnot (~30%) and non-idealities in conversion (50-70% eff), remain with 10 W-hr/kg • Very high cycle capability • Cost is for container & insulator

  27. Collector and Engine Efficiency G = 1000 W/m2 (PV standard) Schott ETC-16 collector Engine: 2/3 of Carnot eff.

  28. Energy Storage Comparison

More Related