One reason human beings can thrive in all kinds of climates is that they can control the qualities of the air in the enclosed spaces in which they live. Air conditioning is the use of mechanical systems to achieve that control in such places as homes, offices, theaters, institutions, factories, airplanes, and automobiles. The most familiar type of air conditioning is…
Tests have determined that people generally feel best under certain temperature, humidity, and air velocity conditions. Temperatures can range from 71° F (21.5° C) with 70 percent relative humidity to 83.5° F (28° C) with 30 percent relative humidity. Relative humidity is the amount of moisture in the air at a specific temperature compared with the amount it could hold at that temperature.
Air conditioners customarily cool by blowing the air through a coil of tubing that contains a cold fluid. The fluid, usually a special chemical, is most often cooled by the process of refrigeration. This process makes use of the relationship between the volume of a substance and its capacity for holding heat. For example, if a quantity of gas at a given temperature is…
