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:

General Information
All components of the refrigerant circuit submitted for quality observation are always to be sealed (use original sealing caps of original part). To date, the original parts (compressor, reservoir, receiver/dryer, evaporator and co ...

Factory Paint Paint Structure
Structure of a Solid-Color Paint System, Conventional Approximately 80-120 µm thick 1 - Steel Panel 2 - Zinc Phosphate Coating 3 - Electr ...

Tires, Dismounting, Wheels without and with Tire Pressure Monitoring System
If equipped check the tire pressure monitoring sensor with the vehicle diagnostic tester and if necessary replace. Note When cleaning disc wheel (rim), the tire pressure monitoring sensor (if equipped) must not come into c ...