Cold Link Africa November/December 2018 | Page 33

FEATURE INCORPORATING COLD CHAIN Role(s) of water in refrigeration By Charles Nicolson A lthough the three phases of water have been involved in cooling throughout our history, until less than 200 years ago, water used for refrigeration was virtually entirely in the form of ice. SOLID PHASE If you were living in the US or one of the other northern hemisphere countries such as England or France during the period from the start of the 19th century through to the early 1900s, when you needed to reduce the temperature of foodstuffs or to cool drinks down to a few degrees above zero, you would use ice. Depending on your location, you might visit the local ice shop or possibly even be expecting a daily delivery of ice. For over 100 years, blocks of ice cut out from natural ice sources and further cut into reduced sizes suitable for domestic purposes and commercial businesses were the main, and often the only means of preserving food and perishables, usually in heavy lead-lined cold box containers that had to be thoroughly cleaned out between successive loads of food and ice blocks. During the first half of the 1800s, refrigeration for the majority of domestic users, as well as small and larger commercial and industrial applications such as food storage depots and breweries, was provided by ice. In fact, this period saw proliferation and growth of ice providers particularly in the US where supplying blocks of ice locally and further afield expanded rapidly into a substantial industry. Two entrepreneurs, Frederick Tudor and Nathaniel Wyeth of New England, saw a huge potential for the ice business and revolutionised the industry during the first half of the 1800s. Tudor became known as the ‘Ice King’ following his successes in developing combinations of insulating materials that enabled ice to be shipped on a profitable commercial basis from New England to tropical climates by reducing losses due to melting from over 60% to less than 10%. Wyeth concentrated on improving ways to cut and shape ice blocks by managing the heavy manual labour involved more efficiently as well as improving storage, transportation, and distribution with less waste. The ice industry, primarily in the US but also spreading to Europe, continued to grow very quickly as more companies entered the business. Ice prices decreased as ice became more widely available from competing suppliers. In 1879, there were 35 commercial ice plants in the US, more than 200 by 1800, and reportedly at least 2 000 by 1910. According to some reports, the market in the US reached 15 million tons of ice in the first decade of the 1900s. However, from about 1870 onwards, it became apparent that the ice being harvested, sectioned, and transported was not all clean and was beginning to cause health problems. Suppliers were, in fact, finding it more and more difficult to find suitably clean sources of accessible natural ice and by the 1890s, increases in general pollution as well as sewage dumping had become threats not only to further growth but also to existing market levels. The first concerns regarding unclean ice arose in the brewing industry, followed by the meat -packing and dairy industries. As more frequent and serious problems occurred, demand grew for refrigeration to be generated on site. CHARLES NICOLSON Charles Nicolson has a physics and chemistry degree from Natal University which he subsequently put to good use by applying speciality chemicals in mining and industrial processes where water is a major factor. This created an enduring interest in water technology, a passion that expanded to the HVAC industry in 1984 when he joined BHT Water Treatment. Since then, water technology in HVAC water circuits has continued to be an abiding interest. Women delivering ice in 1918 during the First World War. COLD LINK AFRICA • November/December 2018 We take a look at the usage (and history) of water in refrigeration systems, focusing individually on each of the different phases of water: solid, liquid, and vapour. www.coldlinkafrica.co.za 33