Refrigeration Compressors

The refrigeration compressor is the heart and heart of the refrigeration system. The capacity and characteristics of the compressor determine the capabilities and characteristics of the refrigeration system. In a sense, the design and matching of the refrigeration system is to reflect the capabilities of the compressor. Therefore, the refrigeration industry in the world has invested a lot of energy in the research of refrigeration compressors, and new research directions and research results are emerging. The technical and performance levels of compressors are changing with each passing day. There are many kinds of compressors. According to different working principles, refrigeration compressors can be divided into fixed displacement compressors and variable displacement compressors.

Mechanical Overview

The refrigeration compressor is the core energy-consuming component of the refrigeration system. The most direct and effective means to improve the efficiency of the refrigeration system is to increase the efficiency of the compressor, which will bring about a significant reduction in system energy consumption. At the same time, it can also avoid the large increase in material consumption caused by only taking measures on the system (such as blindly increasing the heat exchanger area, etc.). With the growing shortage of energy in the world, various countries have paid more and more attention to energy conservation and have put forward higher and higher requirements for the efficiency of energy-consuming products.

Due to the existence of various losses such as friction, leakage, harmful heat transfer, motor losses, flow resistance, noise and vibration, the actual efficiency of the compressor when working is much lower than the theoretical efficiency. Therefore, in theory, any measure that can reduce any kind of loss can improve the efficiency of the compressor. This objective fact has led to a wide range of research on the energy saving of compressors, a wide range of directions, and various research topics and research results.

The research work on the energy saving of compressors in the world mainly focuses on several aspects: study the lubrication characteristics, the friction characteristics of the compressor bearing parts to reduce the frictional power consumption, improve the compressor efficiency; reduce the leakage loss to improve the efficiency of the compressor; The variable-capacity technology achieves energy conservation through the best matching of the output of the refrigeration system and the user's load. The content of this aspect, especially the frequency conversion technology, has been relatively mature and widely known.

The study of gas valves is an old topic but it is also an eternal task. Research to improve the design of gas valves to improve the efficiency of compressors is never-ending and never-ending. There are many researches in this area, from valve materials, movement laws, structure optimization, to applicable theories and test methods. In short, the research on compressor energy saving has become a major hot issue in the refrigeration industry.

Mechanical classification

Volumetric compressor

Rely on the change of the working chamber volume to realize the process of suction, compression, and exhaust. Among such compressors are reciprocating compressors and rotary compressors. Speed ​​compressors rely on high-speed rotating T1 for I1" wheels to do work on steam, the pressure is increased, and the task of conveying steam is completed. There are centrifugal and axial compressors which are commonly used in this type of compressor. Centrifugal type is commonly used. Compressor: Its application is more general, its manufacturing technology is mature, its structure is simple, but its processing materials and processing lT art requirements are low, the cost is low, and its adaptability is strong, it can adapt to a wide range of pressure and cooling capacity, and it has strong maintainability. .

Disadvantages: Can not achieve high speed, the machine is large and heavy, it is not easy to achieve lightweight, exhaust is not continuous, the air flow is prone to fluctuations, and there is a greater vibration when working. Due to the above characteristics of crankshaft connecting rod compressors, there are few small displacement compressors that adopt this type of structure. The crankshaft connecting rod type compressors are mostly used in large displacement air conditioning systems for passenger cars and trucks.

Screw refrigeration compressor

Screw compressor is a rotary positive displacement compressor. It utilizes changes in the slot volume and position of the screw to complete the suction, compression, and discharge IqJ processes of the vapor. Oil-free screw compressors were introduced in the 1930s and are mainly used for compressed air. Later, the screw compressors in the cylinder were injected and the performance was improved. The oil-injected screw compressors were already one of the main types of refrigeration compressors. Screw compressors are classified into twin-screw and single-screw. Twin-screw compressors are customarily referred to as screw compressors.

Variable displacement refrigeration compressor

The variable displacement compressor can automatically adjust the power output according to the set temperature. The air conditioning control system does not acquire the temperature signal of the tuyere of the evaporator m, but instead controls the compression ratio of the compressor according to the pressure change signal in the air conditioning pipeline so as to automatically adjust the m tuyere temperature. In the whole process of refrigeration, the compressor is always working, and the adjustment of the refrigeration intensity completely depends on the pressure regulating valve installed inside the compressor to control. When the pressure at the high pressure end of the air conditioning line is too high, the pressure regulating valve shortens the piston stroke in the compressor to reduce the compression ratio, thus reducing the refrigeration intensity. When the pressure at the high pressure side drops to a certain degree and the pressure at the low pressure side rises to a certain degree, the pressure regulating valve increases the piston stroke to increase the refrigeration intensity.

Fixed displacement refrigeration compressor

The displacement of v is increased proportionally with the increase of the engine speed. It cannot automatically change the power transmission according to the demand of refrigeration, and has a greater impact on the engine's fuel consumption. Its control is generally achieved by collecting the temperature signal from the outlet of the evaporator. When the temperature reaches the set temperature, the compressor stops working; when the temperature rises, the compressor starts to work. Fixed displacement compressors are also controlled by the air conditioning system pressure. When the pressure in the pipeline is too high, the compressor stops working.