1. Solar Stirling Engine Generator
P /3
(Sponsor)
Dr. Alan Raisanen
(Team Guide)
Thomas Gamer (ME)
David Volzer (ME)
Daniel Thering (EE)
Tara Dougherty (ME)
Problem Statement
To design and construct a portable Stirling cycle engine generator that operates using solar energy
Project Background
Harvesting energy from renewable sources (solar) offers a way to provide power in remote locations using local sources
Photovoltaic systems, which convert sunlight directly into electricity, are commonly used because of the direct conversion of energy to power. Radiation can destroy photovoltaic systems
Stirling Cycle engines with an electrical generator can be used to focus sunlight and generate electricity. The advantage of this engine type is that it uses a purely mechanical device to convert energy, and is unaffected by radiation
Objectives
Generator must produce 10 watts at 5 volts of electrical power
Must be weatherproof, and able to last 1 year from the date it is set outside
Provide first generation design for further development of higher power applications
Engine must weigh less than 20 pounds
History
Invented by Dr. Robert Stirling in 1816, his design followed attempts at making an air engine
Three different types of Stirling Engines: Beta, Alpha, and Gamma
Engine Design
Electrical Design
3-D Model of Completed Engine
Completed Engine
Engine Test Results
Rectification Power Circuit
Charging Circuit
Electrical Results
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
12 V R
Vin (V)
Iin (A)
Vout (V)
Iout (A)
Pin (W)
Pout (W)
Efficiency
150 15
0.086
11.953
1.29 75
15.02
0.167
11.958
12 V and 5 V working together
Effciency
Expected
0.029
4.993
0.435
0.1662
0.041
4.983
0.164
4.966 64
Power (W)
at motor shaft 20
at rectifier 16
at USB port
10.68
Summary & Conclusions
The Stirling Engine Generator was successfully built and tested, but unfortunately it was unable run on its own. Despite the engine not functioning as a complete system, each subsystem, thermal, mechanical, and electrical, function successfully as designed. Most design objectives are satisfied and the result is a durable, waterproof, stirling engine with the potential to generate electricity.
Possible reasons for non-functioning engine:
Excessive friction in the seal of the engine
Insufficient compression ratio
Lack of counterweights or necessary momentum at the crankshaft for continuous motion