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Several hot spots in the research of small refrigeration compressors

machine situation "Integration: several hot issues in the research of small refrigeration compressors

as we all know, compressors are the core and heart of refrigeration systems. The capacity and characteristics of the compressor determine the capacity and characteristics of the refrigeration system. In a sense, the design and matching of refrigeration system is to reflect the capacity of compressor. Therefore, the refrigeration industry all over the world has invested a lot of energy in the research of refrigeration compressors, and new research directions and research results continue to appear. The technology and performance level of compressors are changing with each passing day

this paper will make a comprehensive discussion on the technical research and development of small refrigeration compressors in recent years

1 research on high efficiency and energy saving of compressor

compressor is the core energy consuming component of refrigeration system. The most direct and effective way to improve the efficiency of refrigeration system is to improve the efficiency of compressor, which will significantly reduce the energy consumption of the system. At the same time, it can also avoid a large increase in material consumption caused by taking measures (such as blindly increasing the area of heat exchanger) only on the system of Sandvik, which is also one of the few manufacturers in China that can produce high-quality U-tubes. In recent years, with the increasingly serious situation of energy shortage in the world, all countries pay more and more attention to energy conservation and 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 loss, flow resistance, noise and vibration, the actual efficiency of the compressor is far lower than the theoretical efficiency. Therefore, theoretically speaking, any measure that can reduce any loss can improve the efficiency of the compressor. This objective fact leads to a wide range and direction of compressor energy-saving research, and a variety of research topics and research results

at present, the international research work on compressor energy conservation is mainly focused on several aspects: Research on lubrication to help build the sliding characteristics of the next generation space system, friction characteristics of compressor bearing parts to reduce friction power consumption and improve compressor efficiency [1], [2][3]; Reduce the leakage loss to improve the efficiency of the compressor [4]; Frequency conversion or volume change technology is used to achieve energy conservation through the best match between the output of the refrigeration system and the user's load. The content in this regard, especially the frequency conversion technology, has been relatively mature and widely known in the 2017 plan of Jinan testing machine factory, so it will not be repeated here [5]; The research of air valve is an ancient but eternal topic. The research of improving the design of air valve to improve the efficiency of compressor is endless and fruitful. There are many researches in this field, ranging from air valve materials, motion laws, structural optimization to applicable theories and test methods [6]. In short, the research on compressor energy conservation has become a primary hot issue in the refrigeration industry in recent years. Limited by space, this paper will not make a specific thematic discussion here

in recent years, the domestic refrigeration compressor industry has also paid great attention to the energy-saving research of products. The products that have made great progress are mainly the refrigerator compressor industry. With the promotion and support of undp/gef China energy-saving refrigerator project, both enterprises' understanding of energy-saving products that China has become a net capital flow country and the performance of refrigerator compressors have made a qualitative leap. At present, the maximum energy efficiency of refrigerator compressor products of domestic enterprises has reached about 1.95. Domestic refrigerator compressor enterprises have adopted a large number of technical measures, such as high-efficiency motors and even synchronous motors, concave air valves, flat thrust bearings, low viscosity lubricants, new suction silencers, reducing friction losses, and achieved great results. The main problem is that at present, domestic enterprises lack free technology, and the technical route they adopt is mainly imitation. Most enterprises are unconscious and uninterested in establishing their own technical foundation, which restricts the technological development ability of enterprises

compared with the refrigerator compressor industry, the energy-saving research of domestic air-conditioning compressors is still calm. There has been no qualitative change in the efficiency of compressors over the years. The large market demand makes most air-conditioning compressor enterprises focus on expanding production capacity. With the further improvement of the national requirements on the energy efficiency level of air conditioners and the gradual emergence of various hidden dangers in the export of air conditioners in China, this shortsightedness of domestic air-conditioning compressor enterprises will not be able to meet the requirements of the development of energy-saving situation, and will also make the subsequent development of enterprises weak

Research on noise and vibration of compressor

at present, noise has been regarded as one of the serious pollution. As the power source and heart of household refrigeration equipment, the noise problem of refrigeration compressor has become an important index to measure its comprehensive performance. In fact, for a compressor, most of the noise is generated by the shell excited by some noise sources (such as springs, refrigerant pressure pulsations, exhaust pipes, lubricating oil volume, etc.). However, the noise sources and transmission paths of compressors are complex and diverse, which brings great difficulties to the noise reduction of compressors

scholars from various countries have conducted a large number of long-term studies on the noise and vibration of compressors. Here, the main research results in this area are summarized as follows:

the main noise source of refrigeration compressor is composed of aerodynamic noise radiated by inlet and exhaust, mechanical noise generated by mechanical moving parts and driving motor noise:

2.1 aerodynamic noise

the inlet noise of compressor is generated by the pressure pulsation of air flow in the inlet pipe. The fundamental frequency of the intake noise is the same as the gas pulsation frequency in the intake pipe, which is related to the speed of the compressor. The exhaust noise of the compressor is caused by the pressure pulsation of the air flow in the exhaust pipe. The exhaust noise is weaker than the intake noise, so the aerodynamic noise of the compressor is generally dominated by the intake noise

2.2 mechanical noise

the mechanical noise of compressor generally includes the impact of components, friction, vibration of pistons, impact noise of air valves, etc. these noises are random and have wide-band characteristics

2.3 electromagnetic noise