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

...

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:

Socket in the vehicle
Fig. 106 Front centre console: 12-volt socket First read and observe the introductory information and safety warnings Maximum power rating Electrical socket Maximum power rating 12-volt 120 watts The maximum power rating of the sockets may not ...

Overview - Rim
1 - Rim Flange Stop for the side tire bead 2 - Hump (H2) on Both Bead Seats Prevents the tire from slipping off the bead seat when driving around tight curves An extended hump (EH2) is requir ...

Handling wheels and tyres
Fig. 145 Diagram showing how to swap wheels First read and observe the introductory information and safety warningsThe tyres are the most used and most underestimated parts of a vehicle. Tyres are very important as the narrow tyre surfaces are the only contact between the vehicle and the ro ...