AIR CONDITIONING | DEVELOPMENT MILESTONES MILESTONES IN AIR CONDITIONING 1982 1970S 1962 1937 1933 1933 1929 1928 1919 1906 1904 1900 by David Arnold The Acme air washer Patented by Richard Thomas, the air washer was intended to clean the air in ventilation systems and could cool the air for comfort cooling, too. The first prototype was successfully installed in the Chicago Public Library in 1900, to keep books and papers free from accumulations of dust and soot. Air washers became the most common method of air conditioning in large buildings and remained very popular until the 1930s. Psychrometry and control of humidity While researching ways to control humidity for a firm of lithographic printers, Willis Carrier discovered the humidity of air could be reduced by bringing it into contact with moisture at a temperature below the dew point or condensation temperature of the incoming air. This led him to design improved air washers and establish the principles of psychrometry used by air conditioning engineers today. 1906 Air conditioning The term air conditioning was first used by Stuart Cramer, a cotton mill designer, and referred to the control of temperature and humidity to condition yarn processed in cotton mills. He designed the air conditioning for numerous cotton mills in the southern US, and the term was adopted much later by Carrier to define what is now called full air conditioning. Movie theatre mechanical air cooling Air conditioning was introduced to many new luxury movie theatres in the 1920s, as it allowed operators to remain open during the summer, a time when they were usually closed if cooling wasnt available. Fred Wittenmeier, a refrigeration engineer, developed a technique of adding cooling coils to existing hot-blast systems (plenum heating and ventilating systems) connecting the coils to CO2 refrigeration plant. R12 the first synthetic refrigerant gas Early refrigeration systems for air conditioning used refrigerant gases that were toxic, flammable or explosive. General Motors Frigidaire division, a leading manufacturer of systems, was The split air conditioner Frigidaire announced its new Electric Room Cooler. The unit, designed for rooms and small offices, was fully automatic, Fan coil unit Fan coil units (FCUs) were being developed by both Trane and Westinghouse in the early 1930s. The first heating and cooling system, similar to todays four-pipe FCUs, was in the Tribune developing a non-toxic, non-flammable alternative to existing gases. General Motors Research Corporation assembled a team, led by Thomas Midgley Jr, that developed the first synthetic gas, Freon 12, later called R12 and now banned. with a fan that drew air over cooling coils connected to a remote condenser and compressor. Tower, Chicago, when air conditioning was installed in 1934. The units were unique in that they could warm, cool, dehumidify or humidify. They were connected to a new steam-jet chilled-water system and the original steam heating installation.. Reverse-cycle unit heat pump The first free-standing, self-contained room air conditioner an air source heat pump that could heat or cool was patented by Henry Galson in 1932 and manufactured by De La Vergne. The energy source was outside air unit, changed from cooling to heating similar to todays units, with the operation of the evaporator and condenser reversed. The units had hermetically sealed compressors charged with Freon 12 (see above). Induction units In 1937, Carrier adopted the principle patented in 1919 by Albert R Klein of distributing air around buildings at high velocity, to save space required for ducts, and discharging the air through high-velocity nozzles into conditioned spaces. Called the Conduit Weathermaster, the system was first installed in the Statler Hotel, Detroit, in 1943. Induction units were the popular method of air conditioning large buildings until the 1970s. Moduline variable air volume (VAV) Perimeter induction units were very popular by the 1950s, suiting narrow buildings. Richard A Church and colleagues developed a ceiling-mounted, high-velocity variable air cooling system that could cool interior spaces with less variable heat gains and losses. This led to the development of variable air volume that could both cool and heat, which became the most popular method of air conditioning large, open-plan buildings. Direct digital control (DDC) The automatic control of air conditioning in buildings since the early 1900s had pneumatic systems patented by Warren Seymour Johnson in 1895. Computer-based direct digital control (DDC) was introduced around 1980 and led to the development of the ubiquitous building management systems common today. It became cheaper than pneumatic systems and offered many control functions not available until then. Moduline variable air volume (VAV) Daikin Industries obtained a manufacturing licence for the scroll compressor developed by the Trane Company and Arthur D Little in the early 1970s. This resulted in Daikin developing its variable refrigerant volume system in 1982, using the Trane compressor. The system is similar in some respects to a four-pipe fan coil system in that fan coil (indoor) units are distributed in the space to provide cooling or heating. 38 July 2022 www.cibsejournal.com CIBSE July 22 pp38 20th Century aircon milestones.indd 38 24/06/2022 15:24