Ice storage goes back to the earliest days of low-temperature food preservation when stored winter ice was used. Mechanical refrigeration was subsequently introduced to make the ice and it would be transported to where the cooling effect was required. The refrigeration energy available in this way is mainly its latent heat of melting, 334 kJ/kg, as it changes back to water.
Today ice is used in certain industries such as fishing vessels, and as a thermal storage medium. Small icemakers generate ice for drink and food displays. Ice can be made as thin slivers on the surface of evaporator drums, and removed mechanically when the correct thickness has been formed: either the drum or the scraper may rotate. This is a continuous process and the ice flakes fall directly onto the product or into a storage bin below the machine. Smaller units are made as packages with the bin integral and cooled by a few turns of the suction line or by a separate evaporator. Small pieces of ice can be formed in or on tubes or other prismatic shapes made as evaporator tubes, arranged vertically. Water is pumped over the surface to freeze to the thickness or shape required. The tube is then switched to ‘defrost’ and the moulded section thaws sufficiently to slide off, possibly being chopped into short pieces by a rotating cutter. The machine itself is made as a package, and the smaller sizes will include the condensing unit.
Posted in Refrigeration and Air Conditioning