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:

Controls for the heating and fresh air system
Fig. 127 In the centre console: rotary controller of the heating and fresh air system with controls First read and observe the introductory information and safety warnings Button, control Additional information. Heating and fresh air system ...

First aid kit and warning triangle
Fig. 153 In the luggage compartment: holder for the first aid kit Fig. 154 In the luggage compartment. A: Warning triangle under the loading edge, B: Warning triangle in the vehicle tools First read and observe the introductory information and safety warnings First aid kit A first-ai ...

Siemens Wheel Electronics Tire Pressure Monitoring Sensor, Removing and Installing
WARNING If tire sealant was used, then the wheel electronics on that particular wheel must be replaced. The Siemens wheel electronics does not have a microencapsulated ...