Refrigerator+Final

1. History of the Process

The very first types of refrigerations used were snow, ice, cool streams and cellers. It then progressed to wooden box lined with tin or zinc and was sometimes insulated with materials such as cork, sawdust and seaweed. This box held blocks of ice and a dripping pan collected the melting water. Michael Farady liquified ammonia which stimulated cooling and Dr. Goorie created a machine that used ice to create cool air. Today's refrigeratoin uses adapted concepts from Farady's experiments. It consists of compressing gas into a liquid and it absorbs heat. This is exactly what happens in our modern day AC, dehumidifier, refrigerator and freezer. In 1918 Kelvinator invented a fridge that ran on automatic control and in 1922 a wooden cabinet modeled refriderator with a water-cooled compressor was first produced and sold for $714 dollars. In the 1920s and 1930s freezers were introduced. They soon replaced sulphur dioxide with freon 12. The 50s brought automatic ice makes and in the 70s refrigerators becamre more energy efficient.

2. In basic terms: refrigerators remove heat from an enclosed space of substance to lower its temperature. a liquid is rapidly vaporized (through compression) - the quickly expanding vapor requires kinetic energy and draws the energy needed from the immediate area - which loses energy and becomes cooler. Cooling caused by the rapid expansion of gases is the primary means of refrigeration today. Structure: **Compressor ** **Heat-exchanging pipes ** - serpentine or coiled set of pipes **outside the unit** **Expansion valve ** **Heat-exchanging pipes ** - serpentine or coiled set of pipes **inside the unit** **Refrigerant **<span style="font-family: 'Times New Roman','serif'; font-size: 12pt;"> - liquid that evaporates inside the refrigerator to create the cold temperatures Many industrial installations use pure ammonia as the refrigerant. Pure ammonia evaporates at -27 degrees Fahrenheit (-32 degrees Celsius). <span style="line-height: normal; margin: 0in 0in 10pt; mso-margin-bottom-alt: auto; mso-margin-top-alt: auto;"><span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">Diagram:

3. What forms of energy are involved? Refrigerators contain a chemical refrigerant (either chlorofluorocarbon or tetrafluoroethane) inside a sealed cooling system. When this refrigerant is compressed into a small space at high pressure, the refrigerant absorbs heat. As this heated refrigerant passes through the outside radiator -- or condenser -- at the back of the refrigerator, the refrigerant loses this heat. The cooled refrigerant is pushed into the coils in the refrigerator interior to cool the air in the refrigerator compartment. The cooler finally is routed back into the compressor to start the cooling cycle anew. The **Second Law of Thermodynamics** explains the impossibility for heat to flow from a cold object to a hot object without any work being done. Simply stated, heat energy will spontaneously disperse from being localized to being spread out if there is nothing preventing that energy from dispersing. Using this principle, heat energy is removed from the refrigerator's inside compartment. This heat is carried from the compartment and is disposed of through the condenser coils. These coils radiate the waste heat to the air surrounding the coils while cooling the refrigerant, thus completing the work cycle of cooling the refrigerator interior.