automobile air conditioning1

8/7/2019 AUTOMOBILE AIR CONDITIONING1

1/17

ROLL NO :3448


2/17

What is HVACWhat is HVAC ??H.V.A.C Heating, Ventilation and

Air Conditioning system

A HVAC System consists of a chain ofcomponents designed to heat, ventilate

or cool a specific area while

maintaining a defined environmental

cleanliness level.


3/17

Need For HVAC

Easy climate control

Increasing pollution

Ozone layer depletionGreenhouse effect


4/17

Refrigeration Cycle

4 1

23

Enthalpy kJ/kg

Vapor

compression

cycle

1-2 :Compression

2-3 : Condensation

3-4 : Expansion

4-1 : Evaporation


5/17

Construction & Working


6/17

Working

The system must be capable of keeping a

temperature of 22C inside a stationary black

vehicle with four occupants, with an outside

temperature of 40C.

Also, the system must be an efficient heating system,

keeping an internal temperature of 15C with an

outside temperature of 0C.


7/17

Sources of heat to system

Faster the car moves, the greater amount of infiltration into the car and

rate of heat transfer is more.

The sun baking down on the blank road will raise the temp. up 50to 60 C

and thus increases the amount of heat transferred into the car through

the floor.

Because of the relatively large glass areas, metal construction and the flow

of air around the moving vehicle(automobile) is very large ,so the air

conditioning capacity is also large in comparison with A. C. installed at

home.

Quantity of fresh air in.

Moisture movement through car.

Activity level, occupancy patterns, and make- up (male, female, child) of

people.

Quantity of heat directly rejected by sun on car.


8/17

Selection Basis

Scroll Compressors

Compact design and High Volumetric Efficiency (

around 98% ).

Refrigerant R134a

Minimized environmental impact.

Plate-Fin Heat Exchanger-

Compact size, Higher heat transfer capability.

Simple design incorporated to minimize cost.


9/17


10/17

Condenser

Responsible for heat dissipation

The condenser is designed to radiate heat.

Located in front of the radiator

Require good air flow when system is in

operation

Plate fin type heat exchanger with micro channels

used.

Very compact and better heat transfer capability.

Hot compressed refrigerant vapour cools at

constant pressure to liquid.

Overall Heat Transfer Coefficient = 92 W/m2K

Area = 6.87 m2


11/17

Accumulator

Depending on the vehicle, the A/C system will either have a receiver

dryer or an accumulator.

Components contain a desiccant, chemical that attracts moisture.

Prevents formation of corrosive acids on mixture of water and acid.Also act as temporary storage for refrigerant to prevent starving of

evaporator


12/17

Evaporator

Heat absorption component.

Used remove heat from the inside of vehicle.

Secondary benefit - dehumidification.

Unconditioned air passes through a filter before entering the

evaporator.

Plate-fin evaporator with micro channels used.


13/17

Advantages

Travel with comfort for a long distance, In

any type of atmospheric conditions without

tired.

Fuel Efficiency.

Reduction Greenhouse Gas Emission.

Reduction in ozone layer depletion.

Environment Friendly.


14/17

Disadvantages

Engine speed, average and power will reduce

Initial cost of unit

Complicated system


15/17

Future Aspects

Now a days automobile HVAC system are under development

and have used atmospheric carbon dioxide ( CO2 ) as a

refrigerant which is compatible to R134a in performances and

efficiency. This system also has advantage to reduce carbon

emission which in turn results into reduce green house effect.

Also in newer cars a computer control system is used to

control multi-zone HVAC system which can give comfort to a

individual occupant as per the occupant required.


16/17


17/17

Thank You !

automobile air conditioning1

Documents