Paragraph on “Refrigeration” complete paragraph for Class 9, Class 10, Class 11 and Class 12

Refrigeration

Refrigeration is the process of removing heat from substances and keeping things cold. Though a relatively modern technique, the ancients knew ways of extracting heat from water and making it cool. They knew that if chemicals like ammonium nitrate and saltpeter were added to water, it would make it cool by lowering the temperature. Besides this the earliest method of refrigeration was by using ice or snow. Today the process of evaporation, by changing liquid into water vapour, is used for refrigerating.

In 1823 Michael Faraday changed ammonia vapour into liquid by first squeezing or compressing it and then removing the heat from it. When the process is reversed by removing the pressure or compression, it evaporates again thus taking away the heat and leaving behind cold. As a result of this process a technique of changing vapour to liquid, so that it gives up heat, and then reversing it to take up heat was made available. Constant controlling of this process led to the invention of cooling cabinets and subsequently to refrigerators. Based on this principle the first refrigerating machine was invented by a Swiss inventor called Carl Linde in 1874 and refrigerators came into being.