Team P12472
Phil Glasser – Lead Engineer, Electrical Engineer
William Tierney – Mechanical Engineer
Bryan Abbott – Mechanical Engineer
Mike Scionti– Mechanical Engineer
Dr. Alan Raisanen – Faculty Guide, Customer
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Concept Summary
Customer Needs and Specs
System Architecture
Project Status
Schedule
Budget
System Testing Results
Major Issues, Future Work, and Suggestions
Objective Project Evaluation
We wish to demonstrate a small portable Stirling cycle electrical
generator system that can be used to power small portable
USB electronics.
 Stirling generators can use any heat source to produce power
including geothermal, waste heat and in our case solar energy.
 Although mechanically more complex than photovoltaic systems,
Stirling generator system efficiency can out perform
photovoltaic system efficiency.
 Our system will require the design of a solar collector component,
a Stirling engine component, and an electrical generator,
power conditioner and power storage component.
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Customer
Requirement
USB Charger
Stirling Engine
Solar Powered
Autonomous
Operation
Low Maintenance
Cheap
Lightweight
Safe
Comment
Output power through a USB port.
Generator component must be powered by a heat engine
utilizing the stirling cycle.
Obtain heat energy from the sun.
Met
?
Yes
Yes
Yes
Stirling engine must self start.
Operate for one year, maintenance free.
Yes
Yes
Project design must be inexpensive.
Stirling generator must be relatively portable
Stirling generator must not cause any damage to people or
surroundings when operated
Yes
Yes
* Design meets custom all needs
Yes
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Power: Stirling generator must output at least 10 Watts of power
when operating.
Voltage: Generator component must provide a nominal voltage of
5 Volts when operating.
Budget: Stirling generator assembly must be within the budget of
$500. Approved for $517.
Weight: Stirling generator assembly must be within the weight
requirement of 20 pounds.
Mean Time Between Failures: Stirling generator system must
operate for one year before requiring maintenance.
Weatherproof: Stirling generator must be able to withstand all
weather conditions.
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Selected concept was a single
cylinder beta type Stirling
engine with a 90 degree offset
crankshaft to convert linear to
rotational motion
This couples through pulleys
and a timing belt to a PMDC
motor which we used to both
soft start the engine, and
generate power through two
buck-boost converters
Buck-boost circuits power
USB devices, charge lead acid
battery to power Arduino and
soft start
Aluminum
Solar
Collector
Chamber &
Heat Sink
Power &
Displacer
Piston
Crankshaft
Flywheel
Belt and
pulleys
Thermocouples
& MAX6675
PMOS
FET
PMDC
Generator
Arduino
Power
Conditioning
Battery
USB
Output
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Electrical power generation, soft start, and battery charger all working and tested
Seals, Heat sink, solar collector, and separated
piston and crankshaft/flywheel subassemblies
Possible Mechanical issues preventing
engine from running
 Crankshaft Misalignment
 Friction in connecting rod bearings
 Under-designed mounting brackets
Machining took much longer than initially calculated
 Rework on the crankshaft due to issues with construction
 Redesign of mounting brackets
 Base-plate redesign
 Redesign of connecting rod – power piston, displacer piston
connections
 Fine-tuning of piston seals
 Time was managed, engine was still built by week 8 but is currently
not working due to mechanical issues
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The project came in $20.43 over the approved budget of
$517.09
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Over-budget due to under-estimated shipping costs
Estimated
Mechanical $308.20
Electrical
$208.89
Total
$517.09
Actual
$321.51
$216.01
$537.52
USB output begins when motor reaches ~1570 RPM.
 Buck-boost can begin operating when generator
voltage reaches 4.6V, and can operate in a boost
mode down to 3.6V once powered on, and up to 18V
(above the maximum voltage for this motor)
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Custom electronics input and USB output shown at
full load of 1.915A (9.745W), 5.05Vavg, 0.45Vp-p ripple
within USB specification.
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Successfully charged cell phones with power
conditioning board
Max differential 597 ºF at 1 hour, 450 ºF at 12 Minutes
 Logarithmic heating curve, as expected
 Temp Hot ~6X > Temp Cold
 Heating tape used
Differential Temperature (F)
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Time vs Differential Temperature
600
400
200
0
0
10
20
30
Time (Minutes)
40
50
60
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Issue - Stirling engine does not run, possibly due to:
 Crankshaft Misalignment
 Friction in connecting rod bearings
 Under-designed mounting brackets
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Recommended Future Improvements:
 Higher machining precision and sturdier design in
mounting structure and crankshaft.
 Higher precision in crankshaft - connecting rod – piston
assembly.
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Overall, the electric portion of the project met all
of the specs and customer needs.
The mechanical section ran into a couple snags
with respect to friction and mechanical binding.
Built to our design, but unable to run.
For future iterations, we recommend a sturdier
mounting structure and crankshaft and an overall
stringent precision with respect to the crankshaft
assembly.