Refrigerator

=Refrigerator= mkaras12 toc

Purpose
//What is the fundamental purpose of the device?// The purpose of a refrigerator is to keep food cold. Often times, food that is kept cold stays fresh longer. All foods contain bacteria which can spoil the food. By using a refrigerator, the activity of bacteria is slowed down, keeping your foods fresher for longer!

Energy
//What energy transformations are seen in its operation?// Refrigerators often times are plugged into an outlet, which receives electricity from power grids. Electricity flows into the refrigerator, powering the compressor and creating a flow of refrigerants throughout the coils in the refrigerator, starting the refrigeration process.

Controls
//What sensors/controls are designed into the device?// All refrigerators have a thermostat to maintain the desired temperature. These are usually very simple devices. When the refrigerator reaches the set temperature, the thermostat interrupts the electricity flow to the compressor, which stops cooling.

Materials
//What material(s) are essential to the device?//
 * **Refrigerant**
 * Refrigerants are liquids that create cold temperatures by evaporating. Common materials used as refrigerants include pure ammonia and freon. Without any refrigerants, refrigeration would be impossible!
 * **Compressor A **
 * Refrigerants are constantly passing through the compressor. The compressor, well, compresses the molecules of the refrigerant, making the molecules' heat and pressure rise. As the molecules leave the compressor, they flow through the heat-exchanging coils.
 * **Heat-exchanging coils B **
 * The heat-exchanging coils take the refrigerants, which have an increased pressure and heat, and cool them down and decrease their pressure. As it cools, the refrigerant condenses back into a liquid and flows through the expansion valve.
 * **Expansion Valve C **
 * When the refrigerant flows through the expansion valve, it is able to move from a high-pressure zone to a low-pressure zone, so it expands and evaporates. When the refrigerant evaporates, it absorbs heat, making the inside of the refrigerator cold!
 * **Coils D **
 * The coils, located inside the refrigerator, are essential to creating the cool environment that refrigerators are known for. While the refrigerant flows through these coils, it absorbs any heat from the food, leaving cool air.

Science
//What is scientific principle is central to its operation?// The basic idea behind refrigeration is actually quite simple: It uses the evaporation of liquids to absorb heat. As refrigerants flow through the pipes and evaporate, any heat from the foods stored in your refrigerator are absorbed, leaving cool air.

Design
//What does a typical device look like?// Typical refrigerators, most often found in kitchens, are rectangular shaped and tall, usually about 5 1/2 feet in height. They come in many different colors and styles: black, white, stainless steel, etc. Many refrigerators have a freezer attached either to the top, bottom, or side of the fridge. Most refrigerators have a light that turns on when the door is opened as well as shelves and drawers for storage purposes. On the exterior of a refrigerator is a handle attached to the door as well as, sometimes, an ice and water dispenser, which is connected to the freezer.

Evolution
//What changes have there been (or could there be) in this device?// There are several different types of refrigerators that have been developed over time. Originally, the only way to keep meat fresh was by salting them and cold beverages were quite the luxury. Look how far we've gotten! Not only do we have refrigerators powered by electricity, but refrigerators have also been created that are run by gas or propane for those times when you don't have access to electricity.

Competitors
//What other devices serve a similar purpose?// Freezers slow down the activity of bacteria as well by freezing them, preserving your food for even longer than a refrigerator! Air conditioners also take the heat out of an certain area (in this case it would be a room) and ultimately leave a cold environment.

Partners
//What other devices work in conjunction with this device?// Freezers are often attached to either the side, top, or bottom of the refrigerator and serve the same basic function as a refrigerator. The only difference between these two kitchen appliances is that freezers create a colder environment for food. Fans are also found throughout refrigerators, cooling down the pipes, compressor, and other devices that are constantly working to keep your food cold.

Siblings
//What other devices use the same scientific principle?// Air conditioners use the same basic principle as refrigerators. While people may think that an air conditioner pumps in cool air, it actually takes the hot air in your home and is cycled back in as cooler air. This is similar to the refrigerants which remove any heat from the food that is being stored in your refrigerator. Fans are found throughout refrigerators. What other devices use fans as part of their operating system? Well, blenders blend your food with the use of blades that rotate at very fast speeds, similar to the fans used to cool down refrigerators.

Freon Definition
Freon is a brand name for any of a class of liquid or gaseous fluorocarbon or chlorofluorocarbon products, used chiefly as refrigerants.

History of Freon
Refrigerators from the late 1800s until 1929 used the toxic gases, ammonia (NH3), methyl chloride (CH3CI), and sulfur dioxide (SO2), as refrigerants. Many accidents happened in the 1920s because of methyl chloride leakage from refrigerators. Methyl chloride is a colorless, poisonous gas, CH3CI, used chiefly as refrigerant, as a local anesthetic, and as a methylating agent in organic synthesis.People started leaving their refrigerators in their backyards. A well ordered effort began between three American corporations, Frigidaire, General Motors and DuPont to search for a less dangerous way method of refrigerators.

In 1928, Thomas Midgley, Jr. aided by Charles Franklin Kettering invented a "miracle compound" called Freon. Freon represents several different chlorofluorocarbons, or CFCs which are used in commerce and industry. The CFCs are a group of aliphatic organic compounds containing the elements carbon and fluorine, and, in many cases, other halogens (especially chlorine) and hydrogen.

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The compressor pumps low pressure vapor into the condensing unit where it is condensed back into a liquid. Then this is under pressure because the compressor is constantly pumping more vapor into the condensing unit. This liquid (which is called Freon) then goes through the tubing into a coil which has a metering device that has a small opening that the pressurized freon is sprayed through into the larger coil tubing. What this does is allows the freon to expand and this enables it to get cold and absorb heat from the air traveling through the coil. This changes the freon into a low pressure vapor which is again sucked into the compressor and compressed and then the cycle starts over.======