2. REFRIGERATION Refrigeration is a process in which work is done to move heat from one location to another. Uses of Refrigeration :  Industrial uses  Air conditioning  Food storage and distribution  Medical applications

3. CURRENT REFRIGERATION METHODS VAPOUR COMPRESSION

4. VAPOUR ABSORPTION

5. DISADVANTAGES VAPOUR COMPRESSION  Require CFC, HCFC, or other ozone harming refrigerants  Increase global warming effect  Loud/noisy  Typical efficiency is 40-55% of Carnot limit  Moving parts and intricate design  Prone to breakdown VAPOUR ABSORPTION  Requires large heat source  Can't use electricity directly  Require CFC, HCFC, or other ozone harming refrigerants  Increase global warming effect  Inefficient

6. THERMOACOUSTIC REFRIGERATOR  A thermo-acoustic refrigerator (TAR) is a refrigerator that uses sound waves in order to provide the cooling.  In a TAR, the working fluid is a helium-argon mixture, and the compressor is replaced by a loudspeaker. WORKING PRINCIPLE  Pressure variations in sound wave are accomplished by temperature change due to particle oscillations in the gas. For a single medium average temperature at that particular location does not change. When a second medium is present heat is exchanged with it and an expanded particle will take heat from it and compressed particles will reject heat to the second medium.

7. SCHEMATIC FOR TAR

8. ADVANTAGES  The working fluid is typically helium or other inert, benign gases such as air which are environment-friendly unlike common refrigerants.  The simplicity of the design makes it robust, small, and lightweight.  It has almost no moving parts, which translates into a longer working life with fewer repairs. In turn, this makes the system less expensive.  The loudspeaker is TAR’s only moving part which is more durable than a compressor.  It has the ability to attain a higher level of the limiting Carnot efficiency than current refrigeration methods.

9. DISADVANTAGES  The downside of the TAR is that these failed to achieve efficiencies as high as those of standard refrigerator units.  The coefficient of performance of most advanced TAR is only 1 when compared to 3-4 of modern refrigerators.  Another major problem of TAR is that it is either fully on or off.  It leaked an incredible amount of sound that causes ear pain but produces only a small temperature gradient.  These refrigerators were able to cool the air for a short amount of time before the cooled air started raising its temperature.  very much essengerators have failed to achieve efficiencies as high as those as standard refrigeration units.

10. IMPROVEMENTS  Insulate the sound leaks by isolating the system.  Replace the closed cap with a speaker to increase the efficiency by co-generation.  If both ends of a stack are connected to a heat exchangers thus coupling the stack to a heat source and sink, the transfer of heat would be more efficient.  Use conductive material for hot section of resonator  Widen the resonator and use a cone to reduce the losses due to rapid area change.  More practical and efficient reliable temperature sensors such as thermistors should be used.  The composition of stack material may also be changed to any conducting materials like gold,silveror copper.

11. TYPES OF AIR CONDITIONERS ENERGY AND COST SAVING OF LEDS Room air conditioners Central air conditioning systems Heat pumps Evaporative coolers

12. Room air conditioner  Room air conditioners cool rooms rather than the entire home.  Less expensive to operate than central units  Their efficiency is generally lower than that of central air conditioners.  Can be plugged into any 15- or 20-amp, 115-volt household circuit

13. Central Air conditioning  Circulate cool air through a system of supply and return ducts. Supply ducts and registers (i.e., openings in the walls, floors, or ceilings covered by grills) carry cooled air from the air conditioner to the home.  This cooled air becomes warmer as it circulates through the home; then it flows back to the central air conditioner through return ducts and registers

14. Types of Central AC  split-system  an outdoor metal cabinet contains the condenser and compressor, and an indoor cabinet contains the evaporator  Packaged  the evaporator, condenser, and compressor are all located in one cabinet

15. Energy Consumption  Air conditioners are rated by the number of British Thermal Units (Btu) of heat they can remove per hour. Another common rating term for air conditioning size is the "ton," which is 12,000 Btu per hour.  Room air conditioners range from 5,500 Btu per hour to 14,000 Btu per hour.

16. Energy Efficiency  Today's best air conditioners use 30% to 50% less energy than 1970s  Even if your air conditioner is only 10 years old, you may save 20% to 40% of your cooling energy costs by replacing it with a newer, more efficient model  Rating is based on how many Btu per hour are removed for each watt of power it draws  For room air conditioners, this efficiency rating is the Energy Efficiency Ratio, or EER  For central air conditioners, it is the Seasonal Energy Efficiency Ratio, or SEER