In this article, we will explore the main components of an automotive air conditioning system. From traditional designs to the most modern versions, we will analyze their essential parts and variations.
1. Compressor
The compressor is the heart of the air conditioning system, and its design varies depending on the vehicle type and technology:
a. Fixed Displacement Piston Compressor with Clutch:
- Common in medium to high-power vehicles.
- Does not automatically adapt to thermal load, requiring frequent clutch cycling to regulate cooling.
b. Variable Displacement Piston Compressor with Clutch and Mechanical Control:
- Adjusts piston stroke to match thermal load.
- Reduces frequent clutch activation, improving efficiency.
c. Variable Displacement Piston Compressor without Clutch and Electronic Control:
- Uses an electronic valve to regulate capacity.
- Eliminates the need for a clutch, reducing mechanical wear.
d. Rotary Vane Compressor with Clutch:
- Ideal for small vehicles.
- Offers low noise and high efficiency but has lower durability compared to piston compressors.
e. Scroll Compressor with Clutch:
- Uses spiral rotors to compress gas.
- Compact and efficient design.
f. Hybrid Scroll Compressor:
- Combines a mechanical and an electric compressor.
- Adjusts speed based on demand, ideal for hybrid vehicles.
g. Electric Scroll Compressor:
- Operates independently of the vehicle’s engine.
- Uses an inverter to regulate speed, providing quieter operation and functioning even with the engine off.
2. Expansion Devices
These components regulate refrigerant flow for efficient cooling:
a. Fixed Orifice Tube:
- Regulates flow through a fixed orifice.
- Common in basic systems, though efficiency decreases at low speeds.
b. Thermostatic Expansion Valve (Bulb Type):
- Adjusts flow based on evaporator temperature, enhancing efficiency.
c. Thermostatic Expansion Valve (Block Type):
- Similar to the bulb type but with a more compact design, suitable for modern vehicles.
d. Electronic Expansion Valve:
- Uses electronic sensors to adjust flow in real-time.
- Provides precise and efficient system control.
3. Heat Exchangers
Internal and external heat exchangers, such as the evaporator and condenser, are vital for heat transfer:
a. Conventional Coil:
- Made of tube or plate designs in a serpentine shape.
- Lightweight and efficient, commonly used in modern vehicles.
b. Plate and Fin Coil:
- Features plates and fins to increase heat transfer area.
- Suitable for large vehicles due to its high cooling capacity.
4. Dryer Filters
Dryer filters have two primary functions: removing moisture from the system and capturing contaminants. There are two main types:
a. Dryer Filter Before Compressor Suction:
- Acts as a liquid trap before compressor intake.
b. Dryer Filter Before Expansion Device:
- Can be independent of the condenser or integrated into it.
- Also serves as a liquid refrigerant reservoir at the condenser outlet.
5. Refrigerants in the Circuit
Currently, two main types of refrigerants are used:
a. R134a:
- Common in older vehicles.
- Efficient but with a higher environmental impact.
b. R1234yf:
- Used in modern models.
- Features a lower environmental impact, reduced flammability, and higher cost.
- Both gases operate at similar pressures, with R1234yf having slightly higher pressures.
