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:

Engine data
First read and observe the introductory information and safety warnings For reasons of vehicle registration and vehicle taxation, the power output and performance of some engines may vary in some countries from the information given in this booklet. Petrol engines ...

Introduction
This chapter contains information on the following subjects: → Seat heating Additional information and warnings: Adjusting the seat position Seat belts Airbag system Child seats (accessories) Exterior mirrors Luggage compartment WARNING Incorrec ...

Waxing and polishing the vehicle
First read and observe the introductory information and safety warningsWaxing Waxing protects the paintwork. You will need to re-wax the vehicle with a good hard wax if water no longer clearly forms small drops and runs off the paintwork when it is clean. Even if a wax solution is used regul ...