Valeooscope - Air Conditioning System Thermal comfort loop

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Air conditioning comfort and safety

The role of the air conditioning system is not limited to setting a comfortable temperature for the vehicle’s occupants. The system also makes an important, and often neglected, contribution to their safety.

Regulations applying to defrosting zones, as per the standard 78/317 CEE (Europe).

Defrost regulation

Defrosting / demisting

The heating system also defrosts and demists the vehicle’s windows, making for better visibility and improved safety. g The design of the air distribution system, and in particular the layout of the vents and air outlets, plays a crucial role in keeping the windows, and especially the side windows, free of mist. g The air conditioning system helps to eliminate mist on the windows. g The visibility zones of a windscreen must meet given standards which are taken into considera- tion in the vehicle’s design. Every vehicle shall be equipped with a system for removing frost and ice from the glazed surfaces of the windscreen. The windscreen defrosting system shall be effective enough to ensure adequate visibi- lity through the windscreen in cold weather.

B

A’

A

Zone A 80% of surface defrosted within 20 minutes

80% of surface defrosted within 25 minutes Zone A’

95% of surface defrosted within 40 minutes Zone B

The efficiency of the system shall be verified by determining the defrosted area of the windscreen periodically after starting the engine, the vehicle having been kept in a cold chamber for a certain amount of time. g 20 minutes after the start of the test period, the area A must be 80% defrosted g 25 minutes after the start of the test period, the area A’ (passenger side) must be 80% defrosted g 40 minutes after the start of the test period, the area B must be 95% defrosted Electric heated windscreens are a good example of how defrost time and visibility can be perfected. They have an immediate effect and they do not im- pair the occupants’ comfort since they are silent and do not generate strong air flows. But they remain relatively rare, except in cold climates, and their use also depends on the levels of comfort proposed to customers.

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