Transcript ACES Thermoacoustic Presentation

ThermoAcoustic Refrigeration
Dalhousie University
Mechanical Engineering
Team Members
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Trevor Bourgeois
Mike Horne
Peter Smith
Erin MacNeil
Design Description
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Thermoacoustic Refrigerator
Creates Cooling Using Speaker
No Environmentally-Harmful Refrigerants
Mechanically Simple
Relatively Compact and Lightweight
Conventional Refrigeration
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Transfer of Heat from Low Temperature to High
Temperature Area
Common Method is the Vapor-Compression
Cycle
Refrigerant Continuously Compressed and
Expanded
Compressor Provides Work to Move Heat
“Unnaturally”
Conventional Refrigeration
Acoustic Waves
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Transverse Pressure Waves
Moving areas of High and Low Pressure
Ideal Gas Law tells us:
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Adiabatic Compression at constant volume causes
an increase in the temperature of an ideal gas.
PV
T 
mR
Standing Acoustic Waves
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Maximum Pressure at Ends
Maximum Velocity in the Center
Balance between Velocity and Pressure
Pressure
Velocity
Pressure
Thermoacoustic Theory
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Pressure acts as the carrying mechanism
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Higher pressure = larger buckets
Velocity controls the speed
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Higher velocity = quicker transfer
Pressure
Velocity
Pressure
Thermoacoustic Theory
Thermoacoustic Theory
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Gas is adiabatically compressed and translated
Gas heats up to a temperature greater than the
local temperature of the stack.
STACK
GAS
PARCEL
Thermoacoustic Theory
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Gas transfers heat to the stack
Gas cools down and its volume slightly
decreases
STACK
GAS
PARCEL
Thermoacoustic Theory
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Gas moves back to original location returning
energy.
Gas undergoes adiabatic expansion cooling
down below local stack temp.
STACK
GAS
PARCEL
Thermoacoustic Theory
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Heat is transferred from the stack to the gas.
Gas heats up and its volume increases
STACK
GAS
PARCEL
Thermoacoustic Theory
Components
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Speaker
Gas
Tube
Stack
Heat Exchangers
Speaker
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Considerations
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Power Capacity
Frequency Response
Operate At One
Frequency
Choice
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10 inch
Operates At Low
Frequencies
400 W Maximum Power
Gas
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Considerations
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Physical Properties
Sealing
Cost
Choice
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Air
Atmospheric Pressure
Tube
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Considerations
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Length
Reflect Sound Well
Low Acoustic Losses
Does Not Transmit Sound
Choice
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1.5” PVC Tube
Flat End
Stack
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Considerations
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Gap Size
Solid Thickness
Position
Length
Ability Of Sound To Pass Through
Physical Properties
Stack Designs
Heat Exchangers
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Considerations
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Rate Of Heat Transfer
Temperatures
Low Acoustic Impedances
Thermoacoustic Efficiency
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Due to technical immaturity
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Vapor
EFFICIENCY
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Heat exchangers
Sub-systems
Thermoacoustic
Currently refrigerators
are well suited to proportional
20-30%
control
Less
Manufacturing
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Simpler Than Current Model
All Parts Are Easily Obtainable
Sound Insulation
Is There a Need for our Product?
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Stringent Environmental Regulations
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Ozone-depleting Substances Regulations, 1998 were
made under CEPA in Dec. 1998
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International action termed Montreal Protocol
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Support of 165 Countries
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Controls production and exchange of ozone depleting
substances
Effects of the Montreal Protocol
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Increased price of refrigerants, and
refrigeration/cooling units
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New cooling methods will be needed
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Present steps taken by industry will not solve the
problems of the industry (band aid effect)
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Thermoacoustic designs are not affected by these laws
Application of Thermoacoustics
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Design be modified to suit many different cooling
situations
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Refrigerators
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Air Conditioning
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Computer systems cooling
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M.E.M.S cooling
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Transport refrigeration and cold storage warehousing
Market Size
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In America
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1.6 Million Retail Food Refrigerators
540 000 Transport Refrigerators
537 Million ft3 of cold storage
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830 000 refrigerators sold annually in Canada
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70% of purchases are replacement
Primary Market:Home Refrigerators
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Consumer Target Market
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25-44 Years of age
married
home owners
high income
environmentally conscious
This group generally spend more on home
appliances
Customer Needs Evaluation
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Efficiency
Life-span
Capacity (yes/no criterion)
Design and color
Quietness
Brand
Safety
Environmentally Friendly
Other Considerations
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Low maintenance costs
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Freezer size
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Adjustable shelves
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Icemaker
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Ice water dispenser
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Humidity control
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Adjustable thermostat
Best of Class
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Customer Needs Evaluation
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Life Span
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Safety
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Environmentally Friendly
Other Considerations
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Low Maintenance Costs
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Adjustable Thermostat
Barriers to Thermoacoustic
Refrigeration
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Lack of experts in the area
Lack of theoretical and background resources
Resistance from the industry itself
Major Players
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Frigidaire
General Electric
Kenmore/Sears
Maytag
Whirlpool
Plan of Attack/Entering the Market
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Direct attack will fail
Collaboration with brand names and
manufacturers
Financial backing for R&D is directly solved
Project Feasibility
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Mechanical Simplicity (maintenance and operation)
Efficiency
Manufacturing
Diverse Applications
Proportional Control
Fulfills Identified Customer Needs
Overall cost will be more than competitive
Thank You
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Questions??