Air conditioning can be referred as the alteration of air properties to improve thermal quality in an enclosed environment such as a vehicle or a building.
Traditionally, certain societies used basic methods of air conditioning such circulating water through the walls by use of aqueducts. This was done in ancient Rome and Egypt in an attempt to cool the temperature of the air. In the 2nd and 3rd centuries, mechanical systems of air conditioning were invented in China. A rotary wheel measuring three meters in diameter was constructed and manually operated to cool the air.
From the 3rd century to the 18th century, various experiments by different scientists were performed in order to solve the problem of air conditioning. For example, scientist John Hadley explored the principle of evaporation as a means to cool down temperatures of an object below freezing point. John Gorrie, on the other hand, used compression to create ice, which he used to cool air.
Actual breakthroughs in modern air conditioning did not occur until 1902 when Willis Carrier, a graduate from Cornell University, invented the first electrical air conditioning unit. This new invention surpassed all past prototypes because it not only controlled temperature, but also humidity.
Private home air conditioning was first developed in Minneapolis in 1914. Robert Sherman invested the first portable air conditioner in 1945. His system had the capability to cool, humidify, dehumidify, heat, and filter the air.
During these early years, refrigeration and air conditioning used flammable components such as propane and ammonia. These components posed a great danger of leakage. To counter this lurking disaster, in 1928 the first non-toxic, non-flammable chlorofluorocarbon gas – known as Freon was – created by Thomas Midgley Jr. The blend of these non-toxic refrigerants, known as the Dichlorodifluoromethane (R12), was commonly in American vehicles.
In 1994, most A/C units adopted the R-134A. This refrigerant 1,1,1,2-tetrafluoroethane was used because it was less harmful to the ozone layer than the r12 component. Chlorofluorocarbon refrigerants used in the early and mid-twentieth century were phased out and replaced by modern, more environmentally safe refrigerants.
In 1992, the environmental organization known as Greenpeace tasked a specific European laboratory to research climate-safe refrigerants. The organization obtained rights to use a hydrocarbon mix of isopentane and isobutene. This move paved the way for companies like Bosch, Whirlpool and LG, all of which adopted this technology for use throughout Europe and later Asia. However, in the following years, the use of CFC refrigerators was banned in Germany and blocked by companies such as DuPont. The relentless Greenpeace organization did not take the challenge lying down. Therefore, they partnered with global corporations such as Unilever and Coca-Cola to create a coalition known as Refrigerants, Naturally!
Air conditioning can be explained by referring to the refrigeration cycle, or the transportation of heat from a colder location to a hotter one. This requires effort because the process must work in the opposite than what is natural. The compressor receives circulating refrigerant vapor. The vapor is compressed to a higher pressure that increases its temperatures. The vapor is then cooled through the condenser coils and it turns into liquid, which is both condensed and pressurized. The liquid undergoes an abrupt pressure reduction through an expansion valve. This results into flash evaporation that lowers its temperatures rapidly. Finally, the cold refrigerant passes through the evaporator. A fan blows warm air through the evaporator and this causes the cold refrigerant mixture to evaporate, lowering the temperatures.
Some air conditioning units utilize reversed refrigeration cycles. One of these is the heat pump. This appliance has the role of producing heat. Many people install the heat pump as the central air conditioning unit. This process occurs when the indoor evaporator coil – which is supposed to lower the temperature – exchanges roles with the outdoor condenser and discharges cold air.
In extremely hot climatic environments, normal air conditioners do not serve the intended purpose. In these circumstances, evaporative coolers may be used. These appliances depend on outdoor air that they draw inside through cooler pads. In this process, hot air inside the specific compartment is pushed out through the available ventilation.
The design and application of evaporative coolers is simple. The dehumidifier is a special unit used for air conditioning. This appliance differs from “normal” air conditioning because the evaporator and the condenser are located in the same air path. Therefore, the dehumidifier draws all of the heat and maintains it inside its own system. The primary purpose of the dehumidifier is to maintain certain temperature levels in order to avoid mold growth in damp climates and protect sensitive equipment from the impact of excess humidity.
Many air conditioning units are installed in open windows. When this is done, the interior air is cooled as a fan blows over the evaporator while heat drawn from the interior is disseminated into the environment considering. A second fan is blowing outside air over the condenser.
With the split system air conditioning unit, the evaporative unit is inside and the condenser is outside. There is a connection passing through the wall. A portable evaporative system is also common.
Continued innovation related to air conditioning technology is still being performing. Today, there is an emphasis on energy efficiency and toxic gas emissions. Refrigerants that are currently used for air conditioning are believed by many to be a major contributor to global warming. Therefore, measures are being put in place to phase out the use of harmful refrigerants by 2020.