The Classification of Refrigeration Compressor

Refrigeration compressor is the most important component, which is usually called the main engine in refrigeration unit. The refrigerant vapor is increased from low pressure to high pressure and the continuous flow and transportation of the vapor is achieved by the work of the compressor. To put it another way, compressor is the heart of a transport refrigeration unit or Air Conditioner. Today we will introduce the classification of refrigeration compressor, together with their advantages and disadvantages.

Refrigeration compressor can be divided into two categories: Positive Displacement Compressor and Dynamic Compressor.

1. Positive Displacement Compressor:

A certain volume of gas is first inhaled into the cylinder, and then in the cylinder it is compressed and the pressure rises. When the pressure reaches a certain degree, the gas is forced out of the cylinder. The suction and exhaust process of the positive displacement compressor is intermittent and the flow is not continuous and stable.

Positive displacement compressor is classified into reciprocating compressor and rotatory compressor depending on different moving parts.

1) Reciprocating Compressor:

Cylinder is its working chamber. The reciprocating motion of the piston completes the processes of compression, exhaust, expansion and suction and realizes the inhalation, compression and transportation of the refrigerant. The piston compressor is mostly medium (standard refrigerating capacity 60~600KW) and small (less than 60KW). However, there is loud noise while it is in operation and the efficiency is low.

2) Rotatory Compressor

The rotary compressor has one or two rotors in the cylinder. When the rotor rotates, it causes the change of the volume in the cylinder, and realizes the inhalation, compression and discharge of the gas. There are many structural types of this kind of compressor, among which screw, rolling rotor and sliding vane compressor are widely used. Screw compressor has a series of unique advantages, such as simple structure, high reliability, convenient operation and maintenance, mature technology and so on. It has been widely used in refrigeration, air conditioning and a variety of technological processes.

2. Dynamic Compressor

In dynamic compressor, the growth of gas pressure is converted from the speed of gas, that is, to accelerate the gas to a certain high speed, and then slow it down, converting the momentum of the gas to gas pressure, and then discharge the gas. The compression process in the dynamic compressor can be carried out continuously and its flow is stable.

Centrifugal Compressor and Axial Flow Compressor are two main kinds of dynamic compressor. Centrifugal compressor has the characteristics of large flow, high speed, compact structure, smooth operation and so on, but it is not suitable for small displacement and high pressure discharge. Without reciprocating parts, the centrifugal compressor has good dynamic balance and low vibration. Besides, the wearing parts are few, the running cycle is long, the maintenance cost is low, and the service life is long. Axial flow compressor has the characteristics of large capacity, high efficiency and small in size. The efficiency of the axial flow compressor is better than that of the centrifugal compressor.

In general:

Positive displacement compressor is suitable for small flow and pressure range; Centrifugal compressor is suitable for medium flow, medium and high pressure; Axial flow compressor is suitable for large flow, low and medium pressure. Corunlima has made below diagram for easy understanding.