ThermoAcoustic Refrigeration

1
ThermoAcoustic Refrigeration
TARGET

• Dalhousie University Mechanical Engineering

2
Team Members
TARGET

• Trevor Bourgeois
• Mike Horne
• Peter Smith
• Erin MacNeil

3
Design Description
TARGET

• Thermoacoustic Refrigerator
• Creates Cooling Using Speaker
• No Environmentally-Harmful Refrigerants
• Mechanically Simple
• Relatively Compact and Lightweight

4
Conventional Refrigeration
TARGET

• 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

5
Conventional Refrigeration
TARGET
6
Acoustic Waves
TARGET

• Transverse Pressure Waves
• Moving areas of High and Low Pressure
• Ideal Gas Law tells us
• Adiabatic Compression at constant volume causes
  an increase in the temperature of an ideal gas.

7
Standing Acoustic Waves
TARGET

• Maximum Pressure at Ends
• Maximum Velocity in the Center
• Balance between Velocity and Pressure

8
Thermoacoustic Theory
TARGET

• Pressure acts as the carrying mechanism
• Higher pressure larger buckets
• Velocity controls the speed
• Higher velocity quicker transfer

9
Thermoacoustic Theory
TARGET
10
Thermoacoustic Theory
TARGET

• Gas is adiabatically compressed and translated
• Gas heats up to a temperature greater than the
  local temperature of the stack.

STACK
GAS PARCEL

11
Thermoacoustic Theory
TARGET

• Gas transfers heat to the stack
• Gas cools down and its volume slightly decreases

STACK
GAS PARCEL
12
Thermoacoustic Theory
TARGET

• Gas moves back to original location returning
  energy.
• Gas undergoes adiabatic expansion cooling down
  below local stack temp.

STACK
GAS PARCEL
13
Thermoacoustic Theory
TARGET

• Heat is transferred from the stack to the gas.
• Gas heats up and its volume increases

STACK
GAS PARCEL
14
Thermoacoustic Theory
TARGET
15
Components
TARGET

• Speaker
• Gas
• Tube
• Stack
• Heat Exchangers

16
Speaker
TARGET

• Considerations
• Power Capacity
• Frequency Response
• Operate At One Frequency
• Choice
• 10 inch
• Operates At Low Frequencies
• 400 W Maximum Power

17
Gas
TARGET

• Considerations
• Physical Properties
• Sealing
• Cost
• Choice
• Air
• Atmospheric Pressure

18
Tube
TARGET

• Considerations
• Length
• Reflect Sound Well
• Low Acoustic Losses
• Does Not Transmit Sound
• Choice
• 1.5 PVC Tube
• Flat End

19
Stack
TARGET

• Considerations
• Gap Size
• Solid Thickness
• Position
• Length
• Ability Of Sound To Pass Through
• Physical Properties

20
Stack Designs
TARGET
21
Heat Exchangers
TARGET

• Considerations
• Rate Of Heat Transfer
• Temperatures
• Low Acoustic Impedances

22
Thermoacoustic Efficiency
TARGET

• Due to technical immaturity
• Heat exchangers
• Sub-systems
• Thermoacoustic refrigerators are well suited to
  proportional control

Currently 20-30 Less
23
Manufacturing
TARGET

• Simpler Than Current Model
• All Parts Are Easily Obtainable
• Sound Insulation

24
Is There a Need for our Product?
TARGET

• Stringent Environmental Regulations
• Ozone-depleting Substances Regulations, 1998 were
  made under CEPA in Dec. 1998
• International action termed Montreal Protocol
• Support of 165 Countries
• Controls production and exchange of ozone
  depleting substances

25
Effects of the Montreal Protocol
TARGET

• Increased price of refrigerants, and
  refrigeration/cooling units
• New cooling methods will be needed
• Present steps taken by industry will not solve
  the problems of the industry (band aid effect)
• Thermoacoustic designs are not affected by these
  laws

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Application of Thermoacoustics
TARGET

• Design be modified to suit many different cooling
  situations
• Refrigerators
• Air Conditioning
• Computer systems cooling
• M.E.M.S cooling
• Transport refrigeration and cold storage
  warehousing

27
Market Size
TARGET

• In America
• 1.6 Million Retail Food Refrigerators
• 540 000 Transport Refrigerators
• 537 Million ft3 of cold storage
• 830 000 refrigerators sold annually in Canada
• 70 of purchases are replacement

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Primary MarketHome Refrigerators
TARGET

• Consumer Target Market
• 25-44 Years of age
• married
• home owners
• high income
• environmentally conscious
• This group generally spend more on home appliances

29
Customer Needs Evaluation
TARGET

• Efficiency
• Life-span
• Capacity (yes/no criterion)
• Design and color
• Quietness
• Brand
• Safety
• Environmentally Friendly

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Other Considerations
TARGET

• Low maintenance costs
• Freezer size
• Adjustable shelves
• Icemaker
• Ice water dispenser
• Humidity control
• Adjustable thermostat

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Best of Class
TARGET

• Customer Needs Evaluation
• Life Span
• Safety
• Environmentally Friendly
• Other Considerations
• Low Maintenance Costs
• Adjustable Thermostat

32
Barriers to Thermoacoustic Refrigeration
TARGET

• Lack of experts in the area
• Lack of theoretical and background resources
• Resistance from the industry itself
• Major Players
• Frigidaire
• General Electric
• Kenmore/Sears
• Maytag
• Whirlpool

33
Plan of Attack/Entering the Market
TARGET

• Direct attack will fail
• Collaboration with brand names and manufacturers
• Financial backing for RD is directly solved

34
Project Feasibility
TARGET

• Mechanical Simplicity (maintenance and operation)
• Efficiency
• Manufacturing
• Diverse Applications
• Proportional Control
• Fulfills Identified Customer Needs
• Overall cost will be more than competitive

35
Thank You
TARGET

• Questions??