1. Solar Stirling Engine Generator
Project Review
Tara Dougherty
Thomas Gamer
Daniel Thering
David Volzer

2. Overview: Our Project Customer Needs What is a Beta Stirling Engine?
System Architecture
Design Features
System Testing Results: Mechanical and Electrical
Objective Project Evaluation: Success and Failure
Opportunities and suggestions for improvement
Questions?

3. Our Project:
Design and construct a portable Stirling cycle engine generator that operates using solar energy.

4. Customer Needs:
The generator must produce 10 watts at 5 volts of electrical power
Must be weatherproof and operable for 1 year from the date it is set outside
Provide first generation design for further development of higher power applications
Must weigh less than 20 pounds
Total project budget not to exceed $500

5. What is a Beta Stirling Engine?
Single power piston arranged coaxially with the displacer piston.

6. System Architecture Dish Focuses Sunlight Heat up copper cylinder
Pressurize chamber
Move power piston
Turn crankshaft
Turn pulleys
Generator turns
Charges Battery

7. Design Features Machinable Ceramic Insulator
Brass nipple for pressurization
PTFE spring reinforced O-Rings
Turnbuckle linkages
PTFE impregnated bronze bushings/thrust washers
Stainless steel ball bearings
Power Rectification Circuit
Motor Controller
Lithium Polymer Charging Circuit

8. System Testing Results: Mechanical
Heat Tape used as heat source. Note: At time 0, heat tape was at 70 % max power. At time 20, heat tape power was increased to 90 %. At time 35, heat tape power was increased to 99%. At time 55, fan was added to help cool heat sink
Heat Tape used as heat source. Note: At time 0, heat tape was at 70 % max power. At time 20, heat tape power was increased to 90 %. At time 35, heat tape power was increased to 99%. At time 55, fan was added to help cool heat sink

9. System Testing Results: Electrical

10. Objective Project Evaluation: Success and Failure
Mechanical:
Crankshaft can handle 300 RPM
Thermal:
Ceramic disc and heat sink functioned as designed
Electrical:
Power circuit had great overall efficiency and power output
Failure:
Engine did not perform as expected due to:
Excessive friction
Possible lack of crankshaft momentum
Lack of counterweights on crankshaft prevented engine from sustaining motion.
Motor control board inoperative

11. Opportunities & Suggestions for Future Work
Improve seal technology
Improve compression ratio
Sun tracking system
Free standing base to support engine with 360 degree range of motion
Add counterweights to crankshaft
Larger Flywheel
High power testing
Re-evaluation of control logic
Seek outside sources for board fabrication

12. Questions?