ThermoAcoustic Refrigeration

1. ThermoAcoustic Refrigeration Dalhousie University Mechanical Engineering TARGET

2. TARGET Team Members • Trevor Bourgeois • Mike Horne • Peter Smith • Erin MacNeil

3. TARGET Design Description • Thermoacoustic Refrigerator • Creates Cooling Using Speaker • No Environmentally-Harmful Refrigerants • Mechanically Simple • Relatively Compact and Lightweight

4. TARGET Conventional Refrigeration • 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. TARGET Conventional Refrigeration

6. TARGET Acoustic Waves • 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. Pressure Velocity Pressure TARGET Standing Acoustic Waves • Maximum Pressure at Ends • Maximum Velocity in the Center • Balance between Velocity and Pressure

8. Pressure Velocity Pressure TARGET Thermoacoustic Theory • Pressure acts as the carrying mechanism • Higher pressure = larger buckets • Velocity controls the speed • Higher velocity = quicker transfer

9. TARGET Thermoacoustic Theory

10. TARGET Thermoacoustic Theory • Gas is adiabatically compressed and translated • Gas heats up to a temperature greater than the local temperature of the stack. STACK GAS PARCEL

11. TARGET Thermoacoustic Theory • Gas transfers heat to the stack • Gas cools down and its volume slightly decreases STACK GAS PARCEL

12. TARGET Thermoacoustic Theory • Gas moves back to original location returning energy. • Gas undergoes adiabatic expansion cooling down below local stack temp. STACK GAS PARCEL

13. TARGET Thermoacoustic Theory • Heat is transferred from the stack to the gas. • Gas heats up and its volume increases STACK GAS PARCEL

14. TARGET Thermoacoustic Theory

15. TARGET Components • Speaker • Gas • Tube • Stack • Heat Exchangers

16. Considerations Power Capacity Frequency Response Operate At One Frequency Choice 10 inch Operates At Low Frequencies 400 W Maximum Power TARGET Speaker

17. Considerations Physical Properties Sealing Cost Choice Air Atmospheric Pressure TARGET Gas

18. Considerations Length Reflect Sound Well Low Acoustic Losses Does Not Transmit Sound Choice 1.5” PVC Tube Flat End TARGET Tube

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

20. TARGET Stack Designs

21. TARGET Heat Exchangers • Considerations • Rate Of Heat Transfer • Temperatures • Low Acoustic Impedances

22. EFFICIENCY Vapor Thermo TARGET Thermoacoustic Efficiency • Due to technical immaturity • Heat exchangers • Sub-systems • Thermoacoustic refrigerators are well suited to proportional control Currently 20-30%Less

23. TARGET Manufacturing • Simpler Than Current Model • All Parts Are Easily Obtainable • Sound Insulation

24. TARGET Is There a Need for our Product? • 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. TARGET Effects of the Montreal Protocol • 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

26. TARGET Application of Thermoacoustics • 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. TARGET Market Size • 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

28. TARGET Primary Market:Home Refrigerators • Consumer Target Market • 25-44 Years of age • married • home owners • high income • environmentally conscious • This group generally spend more on home appliances

29. TARGET Customer Needs Evaluation • Efficiency • Life-span • Capacity (yes/no criterion) • Design and color • Quietness • Brand • Safety • Environmentally Friendly

30. TARGET Other Considerations • Low maintenance costs • Freezer size • Adjustable shelves • Icemaker • Ice water dispenser • Humidity control • Adjustable thermostat

31. TARGET Best of Class • Customer Needs Evaluation • Life Span • Safety • Environmentally Friendly • Other Considerations • Low Maintenance Costs • Adjustable Thermostat

32. TARGET Barriers to Thermoacoustic Refrigeration • 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. TARGET Plan of Attack/Entering the Market • Direct attack will fail • Collaboration with brand names and manufacturers • Financial backing for R&D is directly solved

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

35. TARGET Thank You • Questions??