Icy Ball

IcyBall was a name given to two early refrigerators, one made by Australian Sir Edward Hallstrom in 1923, and the other design patented by David Forbes Keith of Toronto, Ontario, Canada (filed 1927, granted 1929), and manufactured by American Powel Crosley Jr., who bought the rights to the device. Both devices were unusual in design in that they did not require the use of electricity for cooling. They ran for a day on 2 hours of sunlight, allowing rural users lacking electricity to utilise the benefits of refrigeration.

The Crosley Icyball was an example of a gas-absorption refrigerator, as can be found today in recreational vehicles or campervans. Unlike most refrigerators, the Icyball had no moving parts, and instead of operating continuously, was manually cycled. Typically it would be charged in the morning, and provide cooling throughout the heat of the day.

Absorption refrigerators and the more common mechanical refrigerators both cool by the evaporation of refrigerant. (Evaporation of a liquid causes cooling, as for example, liquid sweat on the skin evaporating feels cool, and the reverse process releases lots of heat.) In absorption refrigerators, the buildup of pressure due to evaporation of refrigerant is relieved not by suction at the inlet of a compressor, but by absorption into an absorptive medium (water in the case of the Icy Ball).

The IcyBall system moves heat from the refrigerated cabinet to the warmer room by using ammonia as the refrigerant. It consists of two metal balls: a hot ball, which in the fully charged state contains the absorber (water) and a cold ball containing liquid ammonia. These are joined by a pipe in the shape of an inverted U. The pipe allows ammonia gas to move in either direction.

After approximately a day's use (varying depending on load), the IcyBall stops cooling, and needs recharging. The IcyBall is removed from the refrigerated cabinet, and the cold ball, from which all the ammonia has evaporated during the previous cycle, is submerged in cool water. The hot ball is then heated gently to boil off the ammonia dissolved in the water inside it. (The solubility of ammonia in water drops as temperature rises.) The pressure in the system rises to around 1.72 MPa, and at this temperature, the ammonia readily passes through the u-tube, and condenses in the colder ball, which is kept cool by the water bath.

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