Air Conditioning

In 1900 there wa very little people could during a hot spell except grumble about the weather or – if they could afford it-go away to the mountains or the seashore. Today air conditioning has changed this. With air conditioning you can be comfortable any where indoors on oven the hottest, stickest day of the year. You will almost certainly find air conditioning in the movie theates you attend., in many of the stores where you family shop, an in the restaurant where you eat. It may even be ini your own house.


What is Air Conditioning?

You know that air conditioning make you feel cool. But air conditioning is more than just cooling. It means keeping the temperature and humidity (moisture content) of airin an enclosed space, weather it is one room or an entire building, at just the right level for the comfort of the people inside. It alse means circulating the air with fans and removing dust from it with filters. In winter it means heating the air and adding moisture if necessary. In summer it means removing moisture by passing the air over cold pipes that collect water from the air, much as drops of water condenses on a cold water glass on a hot, damp day. In fact, we might almost say that air conditioning means creating an artificial, comfortable climate. In this article we shall discuss only cooling.
In dry vlimates air can be cooled simply. The cooler may be no more than a large fan that draws hot, dry air trought a water soaked fiber mat. The air is cooled as it evaporates the water. It is so dry to begin with that the added moisture will not couse discomfort.

How does air conditioning work?


An air conditioning unit does not “add coolness” to the air. It removes heat. An air conditioner work on the same basic principle as a refrigrator-though it is not designed to produce such low temperatures. Heat is taken from the air by the rapid expantion of a refrigerant (cooling subtance) as it turns from a liquid at high pressure to a gas at low pressure. An accompanying illustration show the cycle of operation of a small home type air conditioner. Here the air is cooled directly by the macine. For the sake of simplicity, filters and motors are not shoen in this diagram. In large, central installations, such as those in office buildings and schools, a machine chills water that isi piped to a series of coils. Air from building is drawn over these coils and circulated through the building by blower.

To be partical, an air conditioning unit must be able to maintain a steady temperature. Otherwise people would have turn their units off and on continually as the temperature is maintained by a temperature-regulating device called a thermostat. The tremostat is set at the desired temperature. Itthen switches the cooling unit on off as needed.
The air conditioning system of the future may work by what is know thermoelectricity. A thermoelectric unit is very small and very quiet. It is made up of tiny “couples,” each couple consisting of a pair of semi conductor and connected in parallel to an electric current. These couples produce cooling at one end and heating at the other when direct current flows trough them. This is called the peltier effect. When a way is found to produce these tiny thermoelectric unit cheaply. They may cool abd head your whole house.