MSD 1 : SYSTEMS DESIGN REVIEW

MSD 1 : SYSTEMS DESIGN REVIEWFriday, January 20th 2012

http://en.wikipedia.org/wiki/File:Beta_stirling_animation.gif

Team P12472 : Solar Stirling Generator

https://edge.rit.edu/content/P12472/public/Home

Room 09-4425 10 AM – 12 PM

Project Team and Attendees

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 and Customer

Meeting Purpose

Overview of the project Confirm Engineering Specifications and Customer

Needs Review concepts Propose a design approach and confirm its

functionality Cross-disciplinary review: generate further ideas

Materials Reviewed

Project Description Work Breakdown Structure Project Plan Customer Needs Engineering Specifications Concept Development Proposed Design Risk Assessment

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.

Beta Stirling Cycle

• The Beta Type Stirling Engine consists of

one cylinder containing a displacer piston and a power piston , coupled to a flywheel.

• The working fluid on the far side of the cylinder is heated by some external heat source and the opposite side is cooled by a heat sink or some method of heat rejection.

• As the working fluid on the hot side expands, it pushes the power piston towards the cold end of the cylinder.

• On the cold end the gas contracts , pulling the power piston back towards the hot side.

• The displacer piston acts as a shuttle, moving hot gas towards the cold side and vice versa.

• The power piston and displacer piston rods are linked to the flywheel 90 degrees out of phase , producing output power.

Work Breakdown Structure / Physical Decomposition

Solar Powered Stirling Generator

Stirling Engine (Bryan, Mike,

Will)

Cylinder (Will)

Power Piston (Will)

Displacer Piston (Bryan)

Heat Sink (Mike)

Rods and Linkages

(Mike)

Seals (Bryan)

Generator (Phil)

Motor

Power conditioning

Battery Charge Circuit

USB output

Parabolic Mirror (Will, Bryan, Mike)

Mounting structure

Mirror attachment

place

Engine and generator

attachment place

Base

Many Small Mirrors

Function Tree

Power Small Electronics

Output electrical power to USB

Store electrical power

Condition electrical power

Generate electrical power

Convert solar energy to thermal

energy

Convert thermal energy to

mechanical energy

Protect System

Corrosion resistant

Weather proofing

Function Tree cont.

Convert solar energy to thermal energy

Collect solar energy

Focus sunlight on an object

Place the hot side of a Stirling engine in the

focal point of the sunlight

Mount Stirling engine

Mount solar collector

Function Tree cont.

Convert thermal energy to

mechanical energy

Create a temperature

difference

Heat the working fluid in a Stirling

engine

Cool the working fluid in a Stirling

engineSeal fluid in a

chamber

Convert linear motion to

rotational motion

Convert rotational motion to electricity

Project Plan – MSD 1

• Design Engine parameters

and 3D Cad modeling• Design Mirror and mount• Electrical design

Week 5-8

• Refine and tweak designs • In depth analysis and seek the

aid of professors to look over design

• Final simulations, artwork, and design parameters

Week 8-11

Project Plan

Task Owner M T W R F S S M T W R F S S M T W R F S S M T W R F S S M T W R F S S M T W R F S S M T W R F S S M T W R F S S M T W R F S S M T W R F S S M T W R F S SIdentify team leader WillDecide on team norms and behaviors WillIdentify customer needs WillIdentify knowns and unknowns WillUnderstand full scope of project AllAssess risks and mitigation WillHigh level system design schematic WillUpdate project plan PhilWork Breakdown Structure chart PhilDesign review powerpoint MikeDesign handout PhilDetailed design PhilSystem Design Review PhilPeer review for group members PhilEngine Configuration BryanResearch different configurations of stirling engines BryanEngine Type Selection Matrix MikeDetermine how much torque engine can output WillDetermine operating speed of engine WillResearch types of seals to be used in engine BryanSelect seal to be used in engine BryanDesign engineMaterial Selection WillResearch and select material used for engine block WillResearch and select material for piston WillResearch and select material for displacer WillFinalize material selection WillHeat sink design BryanResearch materials used for heat sinks BryanModel different materials and fin shapes/spacing BryanSize and determine how heat sink will be implimented BryanMirror design WillResearch methods of constructing parabolic mirrors WillSize mirror to needed power input WillDesign mirror mount and structure WillGenerator selection PhilResearch types of motors for power generation PhilSelect motor based upon engine and specs PhilAutostart mechanism design PhilResearch methods of automatically starting a stirling engine PhilDetermine how much torque is needed to start engine PhilDesign autostart circuit PhilBattery selection/power control PhilAppropriately size battery to meet customer needs PhilDesign electronics to control power PhilDesign mounting structures Will

Week 1 Week 2 Week 3 Week 4 Week 5 Week 6

Project Plan



Week 5 Week 6 Week 7 Week 8 Week 9 Week 10 Week 11

Customer Needs USB Charger: Stirling generator must output power

through a USB port. Stirling Engine: Generator component must be powered by

a heat engine utilizing the stirling cycle. Solar Power: Stirling engine must obtain its heat energy

from the sun. Self Start: Stirling engine must start autonomously. Low Maintenance: Stirling generator system must operate

for one year, maintenance free. Inexpensive: Project may not exceed the project budget. Light Weight: Stirling generator assembly must be

relatively portable and need exceed the weight requirement. Safe: Stirling generator must not cause any damage to

people or surroundings when operated.

Customer Needs cont.

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. 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.

Concept Development

Decision Matrices: Engine Configuration – Alpha, Beta, Gamma,

Free Piston, Rotary, Ringborn Linkage – Standard 90 degree offset, Rhombic

Drive Motor – Brushless DC, Stepper, Handwound

Flywheel Battery – Nickel-Metal Hydride, Rechargeable

Alkaline, Lithium Ion, Lead-Acid

Engine Configuration

We are continuing with the Beta Type Stirling Engine

http://en.wikipedia.org/wiki/Stirling_enginehttp://www.ohio.edu/people/urieli/stirling/engines/gamma.htmlhttp://www.bekkoame.ne.jp/~khirata/english/fpse.htmhttp://www.bekkoame.ne.jp/~khirata/english/mk_rot.htmhttp://www.moriya-press.com/illustrations/ringbom_patent.html

Linkages

We are continuing with the 90 Degree Offset Crankshaft

http://en.wikipedia.org/wiki/Stirling_engine

Motors

We are continuing with the AC Stepper Motor

http://www.edn.com/article/510206-Hardware_controlled_brushless_dc_motors_ease_the_burden_on_CPUs.php

http://en.wikipedia.org/wiki/Stepper_motor

http://www.waterfuelcell.org/phpBB2/viewtopic.php?t=800

Batteries

We are continuing with the Nickel-Metal Hydride Battery

http://www.batteryfacts.co.uk/BatteryTypes/index.htmlhttp://www.kollewin.com/blog/lead-acid-batteries/http://www.daviddarling.info/encyclopedia/A/AE_alkaline_battery.html

Proposed Design

Proposed Design

Parabolic Mirror and

Mount

Beta Type Stirling Engine

Crank Shaft and Gearing

Stepper Motor

Power Conditioning

Battery Charge Circuit

USB Output 5V 10W

Soft start Mechanism

Temp sensor with

comparator

Stepper Driver Chip

Arduino with temp sensor

Power FETs

Feasibility Analysis

Feasibility Analysis cont.




5 Volt Output, 2 Amps, 10 Watts Assuming ~60% efficiency of the generator,

18W motor needed Rectify ac stepper voltage to DC by

mixing all the phases through diodes Linear regulator or buck/boost to desired V

for charge circuit and USB output Drive motor to overcome generator torque

Estimated Budget

Materials List

COMPONET DIMENSIONS MATERIAL COST VENDORCylinder 2.55" dia x 8.5" 304 Stainless $87.44 McMaster CarrDisplacer Piston 2.0" dia x 4.6" Aluminum $21.81 McMaster CarrPower Piston 2.3" dia x 1" 304 Stainless $0.00 McMaster CarrEnclosure 8" x 3" x 3" Low Carbon Steel $42.77 McMaster CarrStepper Motor 2.2" x 2.2" x 2.2" $50.00 Allied ElectronicsBattery 2" x 2" x 1" Lithium Ion $30.00 All-BatteryElectronics PCB and IC's $80.00 PCB123 and DigikeyParabolic Mirror 18" dia Aluminum $49.95 Edmund ScientificsStand Plastic/Wood $30.00

Total: $391.97

Risk Analysis

ID Risk Item Effect Cause

Like

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Action to Minimize Risk Owner

1 Parts arrive late Schedule is delayedUnreliable vendor, or part is

ordered too late2 2 4

Constant communication with vendor, good understanding of lead times

Phil

2 Team runs out of time Project doesn't get finished Poor project planning 1 3 3 Follow and update the project schedule Phil

3 System weighs too much Customer needs not met Poor material selection/design 1 2 2Strongly consider weight in engine design and part

selectionBryan

4 Mounting structure failsMirror breaks and/or

generator system breaksPoor mounting design 2 3 6

Good mounting design. Account for weight and weather

Will

5 Parts break during installationNeed to order/make new

parts to complete Careless assembly or poor

assembly procedure2 3 6

Plan out how the product will be assembled with ease

Will

6Requirements change throughout the project

System no longer meets requirements

Customer changed his needs/we change design

1 2 2Stay in close contact with customer throughout

design processPhil

7A total redesign is needed after detailed design review

Goes over budget, doesn't finish on time, significantly

increases work load

Scope of project changes or severe miscalculations were

made in detailed design1 3 3

Carefully complete detailed design with factors of safety

Will

8 Project goes over budget Can't afford to pay for all partsSomething breaks and has to be

re-made/purchased2 2 4 Carefully machine parts, get parts donated Bryan

9 Battery failureCan't regulate current or start

generatorBattery shorts or is run dry 2 3 6

Use a fuse and appropriately size battery or add external power source. Add feature to only allow

charging while engine is running.Phil

10Designed electronics do not function

Generator runs but the USB does not provide power

Faulty circuit design 1 3 3Prototype designs and run in depth simulations.

Have a design review with EE professors.Phil

11Engine does not produce enough power

Customer needs not metEngine is not spinning fast

enough2 2 4

Electronically regulate the voltage and design with a large factor of safety.

Phil

12Thermo sensor fail to accurately measure temperature difference

Engine will not auto-start at an appropriate time

Sensors don't make contact with the cylinder, or faulty

equipment2 1 2

Purchase extra sensors and be sure to have good contact between engine and sensor.

Phil

13 Autostart mechanism fails Engine will not auto-startThermocouple fails, motor fails,

batteries die, poor circuitry or control logic, etc.

2 3 6Prototype designs and run in depth simulations.

Do a power study.Phil

14 Weatherproofing fails System is exposed to the

environmentPoor sealing or mounting of

enclosure.1 3 3 Test seals without system inside. Bryan

Risk Analysis cont.

ID Risk Item Effect Cause

Like

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Impo

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Action to Minimize Risk Owner

15Engine material on hot side melts down

System failsMelting point of selected material is too low or the

focused energy was too great1 3 3

Carefully model the temperature that can be reached with our mirror and properly select metal

Will

16Constructed mirror doesn't have a concentrated focal point

Can't effi ciently heat the hot side of stirling engine

Poor contruction and inprecise parabolic shape

1 2 2 Purchase premade mirror Mike

17Temperature difference does not reach minimum value to operate engine

System will not operateNot imputing enough energy or the heat sink is not working well

enough.2 3 6 Appropriately select mirror and design heat sink. Mike

18 Piston/chamber don't integrateEngine will not operate, either

jam or leak.Tolerance buildup or poor

machining or communication.1 3 3 Measure twice, cut once. Bryan

19 Seal does not functionEfficency of engine drops

significantly.

Seal can ware due to usage, corrosion, or possibly not size.

Deformation of seal.2 3 6

Minimize friction and maximize heat expelled through heat sink

Mike

20 Teammates do work incorrectlyImproper sizing or selection of

components.

Mistakes, not checking eachother work, not

understanding theory.2 2 4

Check eachothers work, run simulations and have design reviews.

Phil

21Lack of communication among team

Progress is not made, work is repeated, components don't

integrate.

Falling out amoung team members.

2 3 6 Weekly meetings, check email frequently. Phil

22Teammates do not do assigned work

Work doesn't get done, trust is lost, and confilcts arise.

Not know how to do the task, a major event arised, or was lazy.

2 2 4If you need help, get help. Let the group now asap if you think there will be trouble completeing the

task.Phil

23Teammates do not meet deadlines

Timeline keeps getting pushed back and project is

getting delayed.

Laziness, high external work load.

1 3 3 Actively manage eachothers time. Phil

24Teammates do not follow team norms

Team does not work effi ciently and a hostile work

environment is created.Ego's and stubborness. 2 2 4

Have a discussion with a moderator. Hang out as group and not do work.

Phil

25 Inability to contact guide/mentorTeam won't know if customer

needs changed or if our design is reasonable.

He get's too busy to dedicate any time to us.

1 3 3 Try to contact him or go to Mark Smith. Phil

26 Reduction of team sizeResources lost, work load is

increased. Project scope may be changed.

Freak accident/disregard for the team.

1 3 3 N/A Mike

27Reallotting of teammate time commitment

Meeting times must change Job status changes 3 2 6 Be forward about time commitment issues Will

Questions?

MSD 1 : SYSTEMS DESIGN REVIEW

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