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:

Battery Charger -VAS5903- Maintenance Charging
Note If the battery is discharged by an electrical consumer during maintenance charging, the Battery Charger -VAS5903- automatically supplies the appropriate charge. Maintenance charging can be performed without time ...

Drawers
Fig. 100 In the front seat: drawer First read and observe the introductory information and safety warnings There may be a drawer under each of the front seats. Opening or closing the drawer To open press the button in the drawer grip (arrow) and open the drawer. To close, push the drawer u ...

Switching the front passenger front airbag on and off manually using the key-operated switch
Fig. 58 In the stowage compartment on the front passenger side: key switch for disabling and enabling the front airbag on the front passenger side First read and observe the introductory information and safety warnings The front passenger front airbag must be switched off when securing a ...