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

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?

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

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

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

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

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

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

System Testing Results: Electrical

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

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

Questions?