Engineering Report: Household Appliances – Refrigerator
Introduction- Refrigerator
After a long day at work, you come home, open your refrigerator and take out a nice cold drink. Ever wonder why it is so nice and cold? In this report, I will be explaining how the refrigerator came about. The main reason for any refrigerator is to keep food/drinks cold as cold temperatures help keep food fresh for longer. Main idea of the refrigerator is to slow down bacteria activity in the food so it takes longer to spoil.
Brief History
The refrigerated coil was invented by Ibn Sina in the 11th Century. This was one of the essential advancements towards the modern refrigerator. The refrigerated coil was used to condense vapours. William Cullen went to the University of Glasgow and demonstrated the first artificial refrigeration system in 1748. He never did use his discovery for practical purposes though.
1805, Oliver Evans designed the first refrigeration machine that didn’t use liquid to cool and instead used vapour to cool.
1834, Jacob Parkins built the first Refrigeration machine for practical use.
1844, John Gorrie built a refrigerator in 1844 based on the design of Oliver Evans. It was used to produce ice for cooling the air for the Yellow Fever patients at the time.
The first practical use of the refrigerator for food was invented by James Harrison in 1857, In 1859, Ferdinand Carre used the same idea but made it more complex. He developed a system that use ammonia for cooling instead of condense vapours. During 1876, Carl von Linden invented the Liquefying gas process which revolutionised the technology in the refrigerator. General Electric released the first refrigeration systems. Freon then used and marketed them as a lower toxicity alternative then the previous refrigerators in the early 1920s.
The Refrigerator has changed majorly impacting the modern society and how food is being stored and kept fresh for longer periods of time. In the modern society, the refrigerator can be kept in many important places such as kitchens as well as offices and pharmacies.
How it works
Refrigerators do something called the ‘Vapor compression cycle’ The basic principle is to run cold liquid continuously around the object that needs to be cooled. This process will take heat out of the object.
The refrigerator needs 5 crucial components, the fluid refrigerant, a compressor, the condenser coil, the evaporator coils and an expansion device.

It all starts with the compressor. This controls the flow of the refrigerant, It raises its pressure and then pushes the refrigerant vapor into the coil on the outside of the refrigerator (normally the back).
The hot gas will meet the normally cool temperatures of the kitchen which turns it into a medium heat liquid.
The refrigerant now cools down as it flows into the coil inside the fridge and/or freezer.
The refrigerant absorbs the heat given off from the objects inside. Ends up resulting cooling down the air when everything is cooled to the max temperature.
The refrigerant evaporates to a gas when exciting the refrigerator and back to the compressor.

This process can be a nonstop process that can work up to 13 years nowadays.
A diagram of how the refrigeration process

Different Shapes and Types of Refrigerator
Refrigerators come in a variety of shapes and sizes, from basic to feature-rich models. Some famous designs are the following:

Top Freezer Refrigerators

A fridge that is designed to for a lot of storage in a fairly tight spot. It is a traditional fridge shape that is typically 80cm wide and can hold up to 622 litres of storage. This allows the wide swing of the doors and the low reach for the lower shelves and drawers.

Bottom Freezer

These refrigerators/freezers typically range around 92 cm wide and has a capacity of 850 litres. The usable space is less than that compared of top-freezers but instead, your fridge shelves are easily scan-able. Only real downside of this is that you will have to dig down into your frozen goods.

French Door

The French door refrigerator has two narrow doors at the top and a freezer below. Typically, around 90cm wide. Usable space cannot be compared to the top-freezer models as the swing doors have the added value of a lot more shelves on the doors. Most of these have the added in-door water and ice dispensers.

Side-by-side

This style has one side fridge and freezer on the other. Widths typically around 95 cm and holds roughly 850 litres in capacity. These narrow doors work well for small kitchens but they don’t open wide enough for wide objects as each side is not that wide. But overall, not as energy or space efficient.

Counter Depth

These have a lower profile than other fridges made for blending in with the build-in cupboards and selves for an all-in-one look.  They may look nicer with the styles of the kitchen but they generally offer less storage. These designs tend to be costlier than your standard refrigerators.

Compact Fridges

Smaller versions of the traditional refrigerators and generally for dorm rooms or home offices. They usually have no freezing capacity,

Freezer-less Refrigerators

As the name states, this does not have a freezing compartment. Usually used for cooling fresh foods. Great option if you don’t need to freeze a lot of foods or have a separate freezing department.

Refrigerator Drawers

These refrigerators hide under the countertop just like your washing machine. These can be pulled out and you to access fresh foods and perishables. Often seen in luxury apartment and kitchens and are normally expensive. Howe ever these cannot hold frozen foods and are not energy efficient.

Wine and Cold drink coolers

Designed to keep wine and cold drinks cooled. These could range from your small compartment fridge to your traditionally sized fridge to the full-sized fridge able to store hundreds of bottles. Modern designs are able to keep different wines at different set temperatures.
Materials used/Analysis
The doors of the refrigerator are typically made of Aluminium or steel sheets. Metal skin on the outside does not only give the door its strength and rigidity but also supports the weight of the food in the door pockets. Insulation between the inner and outer cabinets consists of fiberglass. Fiberglass is used due to its lightweight, extremely strong and also a robust metal. Typically, far less brittle and less expensive. Components of the cooling system are typically made from aluminium, copper, or an alloy. Tubing is usually copper due to the metal’s ability to bend without breaking. Freon remains one of the most commonly used refrigerant. Freon is a stable, non-flammable, moderately toxic gasses/liquid. Most interior features such as cabinet liners or doors are made from a vacuumed-formed plastic because of its price for the strength it provides.
Conclusion
Not many improvements for the refrigerator could be changed in this time. Research has shown the best properties for each section of the refrigerator at the best price. Modern day refrigerators compared to the olden day ones are much more better designed and more powerful while energy efficient. The modern-day refrigerator has been tested safer, more energy efficient and stronger than it has ever been. Many materials were tested for best efficacy before designed and up for sale.
Bibliography
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Real Simple. 2017. How Does a Refrigerator Work? – Real Simple. [ONLINE] Available at: https://www.realsimple.com/food-recipes/tools-products/appliances/how-does-refrigerator-work. [Accessed 20 March 2017].
HowStuffWorks. 2017. The Purpose of Refrigeration – How Refrigerators Work | HowStuffWorks. [ONLINE] Available at: http://home.howstuffworks.com/refrigerator1.htm. [Accessed 20 March 2017].