p12472 solar stirling engine generator: final presentation
DESCRIPTION
P12472 Solar Stirling Engine Generator: Final Presentation. Team P12472 Phil Glasser – Lead Engineer, Electrical Engineer William Tierney – Mechanical Engineer Bryan Abbott – Mechanical Engineer Mike Scionti – Mechanical Engineer - PowerPoint PPT PresentationTRANSCRIPT
P12472 Solar Stirling Engine Generator: Final Presentation
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
Presentation Outline Concept Summary Customer Needs and Specs System Architecture Project Status Schedule Budget System Testing Results Major Issues, Future Work, and
Suggestions Objective Project Evaluation
Project Description 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.
Customer Needs
* Design meets custom all needs
Customer Requirement Comment
Met?
USB Charger Output power through a USB port. Yes
Stirling Engine Generator component must be powered by a heat engine utilizing the stirling cycle. Yes
Solar Powered Obtain heat energy from the sun. YesAutonomous Operation Stirling engine must self start. YesLow Maintenance Operate for one year, maintenance free. YesCheap Project design must be inexpensive. YesLightweight Stirling generator must be relatively portable Yes
Safe Stirling generator must not cause any damage to people or surroundings when operated Yes
Engineering Specifications 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.
Selected Concept 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
System Architecture
Aluminum Solar Collector
Chamber & Heat
Sink
Power & Displacer Piston
Crankshaft
Flywheel
Power Conditioni
ng
Belt and pulleys
PMDC Generat
or
Battery
Thermocouples
& MAX6675
Arduino USB Output
PMOS FET
Project Status 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
Project Schedule
Project Schedule
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
Budget The project came in $20.43 over the approved
budget of $517.09
Over-budget due to under-estimated shipping costs
Estimated ActualMechanical $308.20 $321.51Electrical $208.89 $216.01Total $517.09 $537.52
Electrical Testing Results 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)
Custom electronics input and USB output shown at full load of 1.915A (9.745W), 5.05Vavg, 0.45Vp-p ripple within USB specification.
Successfully charged cell phones with power conditioning board
Mechanical Testing Results 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
0 10 20 30 40 50 600
200
400
600
Time vs Differential Temperature
Time (Minutes)Diff
eren
tial T
empe
r-at
ure
(F)
Major Issues, Future Work, and Suggestions
Issue - Stirling engine does not run, possibly due to: Crankshaft Misalignment Friction in connecting rod bearings Under-designed mounting brackets
Recommended Future Improvements: Higher machining precision and sturdier
design in mounting structure and crankshaft. Higher precision in crankshaft - connecting
rod – piston assembly.
Objective Project Evaluation 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.
Questions?