Air conditioning history - Aire Acondicionado

Esta entrada también está disponible en: Spanish

Contenido

Who invented air conditioning? We tell you the history of air conditioning

Around 1911, Willis Carrier (United States) investigated the steps to achieve a positive (heat) or negative (cold) variation in the temperature of the surrounding environment with the state transition of a gas. However, the purpose for which this type of system was implemented and used was not initially to cool but to dehumidify the air. The evaporation of a liquid with a low evaporation temperature was known before, but there was a loss of the substance used (ammonia) and therefore it was not suitable for continuous use. Carrier devised a system for recovering it in a closed circuit and after a year of work was given the task of solving the problem of controlling air humidity in a Brooklyn printing plant, where the paper became unusable when it wrinkled due to excessive humidity in the air.

Willis Carrier, el inventor del aire acondicionado

Willis Carrier, the inventor of air conditioning

The previous solutions to solve this problem were to increase the air speed or to leave some windows open to counteract the humidity with an opposite air current. Moisture was a big problem in terms of productivity, because it brought an interruption in the activities of the workers and therefore in the work of the printer. Carrier completed the first draft of its air-conditioning system on 17 July 1902, a technology that is the basis of today’s air-conditioning systems.

The term “air conditioning” was initially named by Stuart Cramer, who became interested in Carrier’s study of humidity and air conditioning. Therefore, we can say that Willis Carrier was the inventor of air conditioning.

Details of how an air conditioner works and its construction

The operation of an air conditioner is based on using a thermodynamic cycle that is performed by a heat transfer fluid.

Any air conditioning unit is generally composed of the following main elements:

Compressor: Its purpose is to compress a fluid to achieve an increase in pressure. This fluid is in a gaseous state according to the equations of state of gases (taking as an example the equation of state of an ideal gas). This increase in gas pressure also creates an increase in gas temperature so that the gas at the compressor outlet has a higher pressure and temperature than at the inlet.
Condenser: The function of the condenser is to condense the gas, that is, to transform it into a liquid state. This change of state is made by subtracting heat from the gas so that this absorbed heat is released in the form of heat to the environment.
Expansion valve: The expansion or capillary valve (depending on the type of installation) is a narrowing in the circuit which subjects the liquid to a loss of pressure and therefore to a drop in temperature.
Evaporator: The purpose of the evaporator is to vaporize the liquid by absorbing heat from the outside and transforming this liquid into gas.

The fluids or “refrigerant gases” used in domestic air conditioning units are very varied, but the most commonly used are (or were) the following:

R410 gas bottles

R12: Dichlorodifluoromethane (CCl2F2 composition). (Currently prohibited).
R22: Chlorodifluoromethane (CHClF2 composition). (Currently prohibited).
R407C: Non-azeotropic mixture composed of three gases: R32, R125 and R134a.
R410A: Near-azeotropic mixture of two HFC gases: diphloromethane (R-32) and pentafluoroethane (R-125).

Apart from these elements they are also used to manage and complete their operation: valve system, pressure switches, fans, thermostats, temperature probes and electronic boards.

In domestic and commercial use the most common configuration is composed of two separate units:

An outdoor unit which is mostly where the compressor is arranged
An indoor unit which provides air circulation by diffusion or directly to the environment.

Appearance of air conditioning units

Air conditioning units, as we have mentioned, are usually made up of two separate units: the indoor unit and the outdoor unit. Between these two units, a refrigeration installation of copper piping must be made through which the refrigerant gas or refrigerating fluid will circulate and electrical connections for the correct control and operation of these. The main power supply is usually connected to the outdoor unit since the highest consumption occurs in this unit and this in turn will send voltage through the electrical interconnection with the indoor unit.

These two units will need a drainage pipe to evacuate water from the condensate in these units (cold-only units do not need a drain in the outdoor unit).

There are also compact air conditioning units that combine the outdoor unit and the indoor unit into one unit. These types of units are window units, portable units and compact or “no outdoor unit” units.

[columns] [span4]

Samsung window air conditioning.

[/span4][span4]

Peabody portable air conditioner.

[/span4][span4]

Aire acondicionado compacto sin unidad exterior Olimpia Splendid

Olimpia Splendid compact air conditioner without outdoor unit.

[/span4][/columns]

Compact window units are usually the units that are “embedded” in a wall with access to the outside of the dwelling in order to have the inner unit part inside the dwelling and the outer unit part outside the dwelling. These units are currently in disuse.
The portable units exist with “backpack” or “without backpack”. The units with a backpack consist of an indoor unit and an outdoor unit connected to each other by flexible pipes, being the indoor unit in this case the one with the compressor inside and leaving in the outdoor unit only the condenser with a fan. The units “without a backpack” are usually composed of one or two air tube inlets/outlets to the outside where the air necessary for the cooling of the condenser will be sucked in and out. These units with only one air outlet (discharge of air to the outside) have a very limited performance since, as they do not have an input of external air for cooling, they use the treated air from the inside to cool it and expel it to the outside with its consequent loss of performance.
The compact units or also called without an outdoor unit are compact air conditioning units that integrate both the indoor and outdoor unit, being a mixture between window units and portable two-pipe units. This type of unit is “hung” on the wall in the same way as an indoor split unit, but with stronger anchors as they are heavier units as they have a compressor for the discharge and suction of the air from the compressor, they are drilled into the wall behind the unit and are hidden from view by two 150 mm holes to achieve the correct supply and discharge of air.

Types of air conditioners

Cooling only and heat pump units

Air conditioning units can be divided into two large families depending on their characteristics:

Cold only units.
Heat pump units.

The big difference between these two types of family is that heat pump units, in addition to cooling air in summer, can also heat it in winter by means of a four-way valve and operating cycle inversion, by subtracting heat from the outside air and injecting it into the interior.

On-off units and inverter air conditioning units

Another distinction is related to the technology used for its operation:

On/off air conditioning units.
Inverter air conditioning units.

The technology of the air conditioning units on/off is older, simpler and more economical but it has several disadvantages as we saw in this entry; a greater consumption since when turning on the compressor this starts in its maximum power remaining in this one during all its operation, a smaller yield, much smaller energetic coefficients than the units inverter, high intensity peaks in the current, greater outer sonority, more limited operation to extreme outer temperatures, etc. On the other hand, inverter air conditioning units, thanks to this technology, manage to electronically modulate the power of the unit, being able to reduce it and increase it depending on the required needs.

Power consumption

Air conditioning units, like many household appliances and electronic devices, are subject to European Union energy efficiency standards and must be rated according to their energy consumption. These classes have as their nomenclature:

Coeficiente energético aire acondicionado

Air conditioning energy coefficients. The energy coefficient A+++ is the most efficient, with G being the least energy efficient.

Generally, in energy classes A++, A++, A+, and B we usually find inverter air conditioning units, while On/Off air conditioning units are usually included in energy classes C or lower.