DESIGN AND CONSTRUCTION OF A PORTABLE REFIGERATOR
CHAPTER 1
1.1. HISTORY OF REFRIGERATOR
A refrigerator is a popular household appliance that consists of a thermally insulated compartment and a heat pump (mechanical, electronic or chemical) that transfer heat from the inside of the fridge to its environment, so that the inside of the fridge is cooled to a temperature below the ambient temperature of the room.
Refrigeration is an essential food storage technique in developed countries, of which the lower temperature lowers the reproduction rate of bacteria. So therefore, the refrigerator reduces the rate of spoilage.
Refrigerator maintains a temperature of few degrees above the freezing point of water, and also the optimum temperature range for perishable food storage is 3 to 5ºC (37 to 47ºF). Another common device that maintains a temperature below the freezing point of water is known as the FREEZER.
The refrigerator replaces the ICEBOX which had been a common household appliance for century and half, for these reasons the refrigerator in American usage is sometimes referred to as the ICEBOX.
The first artificial refrigeration system began in the mid-1750s and developed in the early 1800s. In 1834, the first working vapor-compression refrigeration system was built. And also, the first commercial ice-making machine was invented in 1854 and in 1913 refrigerator for home use was invented. In 1923, Frigidaire introduced the first self-contained unit, and the introduction of Freon in 1920s expanded the refrigerator market.
Newer refrigerators may include automatic defrosting chilled water and ice from a dispenser in the door. Domestic refrigerators and freezers for food storage are made in a range of sizes, among the sizes; the smallest is a 4l Peltier refrigerator which can hold about 6 cans of beer while the largest size is as tall as a person and about 1m wide with a capacity of 600l.
1.2.  HISTORY OF REFRIGERATION TECHNOLOGY
The history of artificial refrigeration began when a Scottish professor William Cullen design a small refrigerating machine in 1755. Cullen used a pump to create a partial vacuum over a container of diethyl ether, which then boiled absorbing heat from the surrounding air. This experiment by Cullen created even a small amount of ice but had no practical application at that time.
In 1805, American inventor Oliver Evans described a closed vapor-compression refrigerator cycle for production of ice by ether under vacuum. In 1820, the British scientist Michael faraday liquefied ammonia and other gases by using high pressures and low temperatures.
