Design And Fabrication Of A Mobile Refrigerator

1.0 INTRODUCTION
It was noticed that people living in the regions close to ice line, that the flesh of animals, or fish caught during the winter kept well, while those caught during the summer decayed as the snow melts.
The value of ice as a preservative was known and put into use some thousands of years ago. In winter it was cut, and moved into ice house which was built into the ground to make use of the insulating properties of tyer soil; such structures was described as shin chiny by Chinese poet.
Also, in the Middle East, and India, water was chilled by evaporating it through porous clay ports, which were buried overnight in favourable conditions, it could be made cooled enough to form ice.
About 1748, William Cullen made the first move toward the use of a modern system by investigating the effect of evaporating ethyl either into a partial vacuum. Not until 1834 that Jacob Perkins patented a closed – cycle refrigeration system using a compressor. It also patented a high pressure hot water heating circuit the same year.
An air – cycle plant for making ice and to cool air for circulating was developed by John Girrie ten years later, through his hospital in flourish. This was the beginning of the race with new beginning of new Engineering innovations following quickly after new scientific theories. Much development work was found on vapour compression system in 1850’s
James Harrison units for meat freezing and brewery applications in Australia while twinning ice – making equipments earned round in USA.
The introduction of ammonia as a refrigerant enabled efficiency and reliability to be improved in later years. This new founding inspired new generation of reciprocation compressors which was used by Ferdinand Carrie in the first viable absorption refrigeration system.
In the 19th century, refrigeration cam of age due to some work by William Thompson who later became Lord Kelvin. The products of his Long Life (1832 – 1907), reflect many interests ranging from refrigeration’s to telegraphy. In retrospect, refrigerating or refrigerants did more that anything to hold up the development of refrigeration. Many of those refrigerants were poisonous or explosive or both, while others functions only at pressure so high as to require compressors and system components to be constructed like battleships, with prime movers to match it.
In 1928, the vice president of united state of America became convinced that refrigeration could get nowhere unless a new refrigerant could be found to substitute the poisonous ammonia.
This problem was passed to research chemist Thomas Midgely; Midgley and his associales Hennece and Mc Nary had an idea of using a compound containing fluorine to solve the problem. It took them only two days to find it. This was done by removing two atoms of chlorine from tetrachlornmethan (carbon tetrachloride) molecules and replacing them with two atoms of fluorine to make the compound dichlorodifluro methan CC12F2.
Tests confirmed this compound to be suitable, non – flammable and usually low level toxic. This new refrigerant was name from 12 (R12) by the sole administrator of the company. It enables equipment manufactures to think in terms of smaller and highly built compressors and system components than the previous ones. Some of the properties of R12 that made it more acceptable are:-
1. It does not attack coppers
2. it is not toxic
3. it is not explosive
can be used for both air – conditioning as well as refrigeration. This development was restricted by the 2nd world war.
The end of the war made manufacturing facilities available and there was a boom in refrigeration and air – conditioning which has continued up to this day. The boom up to the domestic appliances revolutionized the refrigeration industry and its commercial outlets. Bigg4er and better cold stores were needed at the deck certainly, but new cold stores were demanded by complete distribution, chains refrigeration was not for imported foods alone. Demand came all sides plant to freeze vegetables close to the fields.
These were other areas for expansion apart from food, to answer medical needs for blood banks, for antibiotic, for making ice for compresses and low temperature surgery and for preserving certain tissues that pathologists worked on.