Volkswagen Polo Service & Repair Manual: Physical Principles

Volkswagen Polo Service & Repair Manual / Refrrigerant R134a Servicing / A/C System, General Information / A/C Technology Basic Principles / Physical Principles

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

1 -	gaseous (invisible)

2 -

vapor

3 -

fluid

4 -

solid

Physical Principles

When water is heated in a vessel (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. The warmth is extracted from gaseous water, vapor forms first, then water and then ice.

A -	Heat absorption

B -	Heat emission

Physical Principles

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.

A/C Technology Basic Principles

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Pressure and Boiling Point

The boiling point given in tables for a liquid is always referenced to an atmospheric pressure of 1 bar (14.5 psi). If the pressure acting on a fluid changes, its boi ...

Other materials:

Rear view
Fig. 3 Overview of the rear of the vehicle Key for : Roof aerial High-mounted brake light Rear window Rear window heating Window aerial Rear window wiper Volkswagen badge, used for opening the tailgate Tail light cluster Number plate lights ...

Technical Requirements
Factory-Installed Trailer Hitch If the vehicle was already delivered from the factory with a trailer hitch, all of the technical and legal requirements for towing a trailer have already been taken into account. Note that a »13-pin« trailer ...

Using the vehicle in other countries and continents
First read and observe the introductory information and safety warningsThe vehicle has been manufactured specifically for a particular country and complies with the registration regulations that applied in that country at the time of vehicle production. If the vehicle is to be sold in anothe ...