Understanding Air Conditioner Compressors

In an air conditioning system, the compressor is a vital component. Its main job is to compress the refrigerant gas, increasing its temperature and pressure. This high-pressure, high-temperature gas then flows to the condenser coil, where it releases heat and turns into a liquid. This process is fundamental to the refrigeration cycle that cools the air.

Types of Air Conditioner Compressors

There are several types of compressors used in air conditioning and refrigeration systems, each with its own design and applications. Let's look at the options provided and determine which one is not a type of compressor.

• Scroll Compressor: This is a type of positive displacement compressor. It uses two interleaved scrolls, one stationary and one orbiting, to trap and compress the refrigerant gas. They are known for their efficiency, quiet operation, and reliability, making them popular in residential and light commercial air conditioning.
• Rotary Compressor: Also a positive displacement compressor, rotary compressors use a rotating roller or vane inside a cylinder to compress the refrigerant. They are typically smaller and lighter than other types and are often found in window air conditioning units and smaller split systems.
• Centrifugal Compressor: This is a dynamic compressor, not a positive displacement type. It uses a rapidly rotating impeller to accelerate the refrigerant gas outwards, converting kinetic energy into pressure as the gas slows down in a diffuser. Centrifugal compressors are generally used in very large air conditioning systems for commercial and industrial buildings.
• Absorption: This is where the key distinction lies. An absorption refrigeration system is a type of cooling system that uses a thermal process, typically heat energy, to produce cooling. Unlike traditional vapor-compression systems that use a mechanical compressor, absorption systems use a chemical process involving an absorbent (like water or lithium bromide) and a refrigerant (like lithium bromide or water, respectively) to create the pressure difference needed to circulate the refrigerant and achieve cooling. The "compressor function" in an absorption system is achieved through heat and chemical reactions, not by a mechanical compression device.

Analyzing the Options

Based on the descriptions above:

• Scroll, Rotary, and Centrifugal are all distinct types of mechanical or dynamic compressors commonly used in air conditioning and refrigeration cycles.
• Absorption refers to an entire refrigeration *cycle* or *system* that operates differently and does not rely on a mechanical compressor like the other types. The term "absorption" describes the *method* of refrigeration, not a component within a vapor-compression cycle.

Therefore, 'Absorption' is not a type of air conditioner compressor. It is a different technology for achieving refrigeration.

The final answer is Absorption.

Revision Table: Air Conditioner Compressor Types

Additional Information: Absorption Refrigeration

Absorption refrigeration cycles are an alternative to the standard vapor-compression cycle. They are particularly useful in situations where a source of waste heat is available, such as from industrial processes or solar thermal collectors. Key components of an absorption system include a generator, condenser, evaporator, and absorber. The generator uses heat to separate the refrigerant from the absorbent, creating high-pressure refrigerant vapor, which performs the cooling effect in the evaporator, similar to a vapor-compression system. However, the low-pressure vapor then enters the absorber, where it is reabsorbed into the absorbent, and the solution is pumped back to the generator, completing the cycle. This eliminates the need for a power-consuming mechanical compressor.