Manufacturing Systems Project .
Topic : How to manufacture a Refrigerator for long distance transporation of goods. 1.0 Introduction :
This project will look at the manufacturing processes involved in producing a refrigerator that allows perishable goods to be transported over long distances. In reality we owe our great choice of foods in supermarkets to this invention. Companies like Thermo King from America have been making refrigerators for many years and are a large supplier of them to the world. They have a factory in Galway Ireland. The manufacturing processes involved and many and varied from sheet metal cutting to sub assemblies production. There is so much to be learned about manufacturing systems by researching this product. This project will look at the following areas in relation to manufacturing engineering in the production of a refrigerator in Thermo King Galway.
1. The different manufacturing processes required to make a refrigerator. 2. The type of production system in operation in the factory. E.g , J.I.T. 3. The layout of the factory.
4. The inventory Control System used.
5. Quality Control in manufacturing processes.
6. Plant capacity.
A visit to the factory premises in Galway at the kind invitation of the company provided the author with the majority of the information contained in this project. To get an understanding and appreciation of the value of refrigeration and how it works, the history and mechanical engineering theory of refrigeration will be briefly explained at the beginning.
2.0 The History of Refrigeration.
Before 1938 refrigeration did not really exist. Wet ice and salt were used to preserve poultry, dairy products and meat. People used “larders” in their houses to keep the meat and other foods cool and fresh. In the haulage business many cargoes suffered heavy losses and spoilage moving food products around. There was a great ‘need’ for a refrigeration product to be made that would assist hauliers in transporting food items long distances without having losses. In 1938 the United States Thermo Control Company built the first refrigerator and by 1942 they were being used all over the Unites States. The company later changed its name to Thermo King. The first units were built to cater for 20 ft trucks that transported goods over short to medium distances but over the years larger units were needed to provide refrigeration for 40 ft containers that could travel long distances. During the 1950’s and 1960’s research and development saw better and more capable refrigeration units being made. The areas where refrigeration was used expanded greatly and units were produced for ships, the domestic house market and aircraft. Today refrigeration units are used in every business where food is kept or transported. In it one of the greatest inventions of all time and one which allows the world to have such a huge variety of food available to it. 3.0 Refrigeration Theory.
Refrigeration involves the transfer of heat. When a system or space is ‘cooled’ it means that the heat has been taken out. In every mechanical refrigeration system there are four main components that do this, these are, 1. Compressor – it pressures the refrigerant liquid and forces it through the refrigeration unit. 2. Condenser – this removes the heat from the refrigerant liquid 3. Expansion valve – this meters the amount of refrigerant to the condenser coils. 4. Evaporator Valve – picks up heat from the load.
When a refrigerator is started a gas is compressed and pumped into the condenser. Here it changes state from gas to liquid giving off heat energy. This heat is taken out of the space to the outside air. The liquid then goes into the evaporator and a pressure drop takes place which changes the liquid to a gas again and heat is absorbed by the refrigerant back into the compressor. The cycle is then repeated. The process of evaporation and...
References: 1. Thermo King, (2014) online website, available at, http://www.thermoking.com/
2. Danfoss Corporation (2007), online publication, available at, http://www.danfoss.com/nr/rdonlyres/f35695fe-f4a2-40b9-847f-e81e20a5eea8/0/pf000f202.pdf
3. Kreith, F. (2000) “Air Conditioning and Refrigeration Engineering”, CRC Press, 1999
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