Different Types of Compressors Used in Refrigeration Systems

 Different Types of Compressors Used in Refrigeration Systems

Compressors are the heart of refrigeration systems. They circulate the refrigerant, increase its pressure, and ensure the continuous cycle of heat absorption and rejection. Without compressors, modern cooling systems like refrigerators, air conditioners, and industrial chillers would not function.

In this article, we’ll explore the different types of compressors used in refrigeration systems, their working principles, and applications.

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🔧 1. Reciprocating Compressors

Reciprocating compressors use the back-and-forth motion of a piston to compress vapor refrigerant.

Applications

• Suitable for refrigerants with low volume per kg and large pressure differences (e.g., NH₃ (R-717), R-12, R-22, CH₃Cl (R-40)).
• Available in sizes from 0.5 kW (domestic refrigerators) up to 150 kW (large industrial systems).

Types

• Single-acting vertical compressors → Cylinders arranged vertically, radially, or in V/W form.
• Double-acting horizontal compressors → Cylinders arranged horizontally for higher capacity.

Working Principle

1. Suction Stroke – As the piston moves downward, cylinder volume increases, pressure drops, and the suction valve opens. Refrigerant vapor enters the cylinder.
2. Compression Stroke – The piston moves upward, reducing volume and increasing pressure.
3. Discharge Stroke – When cylinder pressure exceeds discharge valve pressure, the valve opens, and refrigerant is pushed into the condenser.
4. The cycle repeats continuously.

👉 Reciprocating compressors are widely used in domestic refrigerators, window A/C units, and medium-to-large industrial systems.

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🔧 2. Rotary Compressors

Rotary compressors compress refrigerant using rotating blades or rollers. They are positive displacement compressors with negligible clearance, making them efficient for high-volume applications.

Applications

• Commonly used with refrigerants like R-134a, R-22, R-407C, R-144, and NH₃.
• Preferred in compact systems like split air conditioners and household refrigerators.

Types

• Single Stationary Blade Type

  • Consists of a stationary cylinder, roller, and shaft with an eccentric.
  • A spring-loaded blade maintains contact with the rotor, separating suction and discharge sides.
  • As the rotor turns, refrigerant is compressed and discharged.

• Rotating Blade Type

  • Contains a slotted rotor with multiple blades.
  • Rotor center is eccentric to cylinder center.
  • Blades are forced against the cylinder wall by centrifugal action, trapping and compressing refrigerant.

👉 Rotary compressors are compact, quiet, and efficient, making them ideal for domestic and light commercial refrigeration systems.

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🔧 3. Centrifugal Compressors

Centrifugal compressors use centrifugal force to increase refrigerant pressure.

Applications

• Best suited for refrigerants requiring large displacement and low condensing pressure (e.g., R-134a, R-407C).
• Commonly used in large-capacity chillers and industrial refrigeration plants.

Working Principle

1. Refrigerant vapor enters the impeller at low pressure.
2. The impeller rotates at high speed, pushing refrigerant outward to the periphery by centrifugal force.
3. The refrigerant exits the impeller at high velocity.
4. A diffuser converts kinetic energy into pressure energy, delivering high-pressure refrigerant to the condenser.

👉 Centrifugal compressors are efficient for large-scale cooling systems, offering quiet operation and high capacity.

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📊 Comparison of Compressor Types

✅ Conclusion

Compressors are the driving force behind refrigeration systems.

• Reciprocating compressors are versatile and widely used.
• Rotary compressors are compact and efficient for domestic applications.
• Centrifugal compressors are ideal for large-scale industrial cooling.

By understanding the types, working principles, and applications, learners and professionals can better appreciate how refrigeration systems are designed and optimized for efficiency.