Physical Principles

The four known states of water also apply to air conditioning system refrigerants.

Fig 1: Four States Of Water

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1. Gaseous (invisible)
2. Vapor
3. Liquid
4. Solid

When water is heated in a container (heat absorption), water vapor can be seen to rise. If the vapor is further heated through heat absorption, the visible vapor turns into invisible gas. The process is reversible. If heat is extracted from water in gaseous form -A-, it changes first to vapor -B-, then to water and finally to ice.

Fig 2: Diagram Of Heat Absorption & Heat Emission

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A - Heat absorption

B - Heat emission

Heat Transfer

Every substance consists of a mass of moving molecules. The fast moving molecules of a warmer substance give off some of their energy to the cooler and thus slower molecules. As a result, the molecular motion of the warmer substance slows down and that of the colder substance is accelerated. This process continues until the molecules of both substances are moving at the same speed. They are then at the same temperature and no further heat exchange takes place.