Development trend of compressor for household appl

Energy conservation and environmental protection: the development trend of household appliance compressors

at present, China has 130million refrigerators and more than 100million air conditioners. In the next few years, the annual new power consumption of domestic air conditioners in China will reach 20million kW, accounting for more than half of the annual new power generation in the country. In summer, the energy consumption of air conditioners is the most prominent, which has become one of the main reasons for power shortage. According to statistics, in the hottest days in Beijing every year, the power consumption of air conditioning (including central air conditioning) accounts for 40% of Beijing's power consumption, while that of Shenzhen has reached the level of 50%. On average, the current energy consumption of air conditioning has accounted for 20% of China's total power consumption. The power consumption of air conditioners has ranked first among all kinds of household appliances, with an annual power consumption of 50 ~ 70billion kwh. The second is the refrigerator, with a power consumption of 40 ~ 50billion kwh. Therefore, reducing the energy consumption of air conditioners and refrigerators is a severe challenge faced by scientific research departments and household appliance manufacturers. In addition, energy conservation itself is also closely related to environmental protection. Energy conservation is not only to save energy and ensure the safety of China's resources, but also, more importantly, to reduce the emissions of harmful gases such as co through energy conservation, so as to reduce the resulting "greenhouse effect". Therefore, foreign countries also study the issue of energy conservation as an environmental protection issue. It can be seen that energy conservation is not only the development trend of household appliances, but also an important part of protecting the environment and achieving sustainable development

countries all over the world have paid full attention to energy conservation and formulated corresponding laws and regulations. China is an energy importing country, and energy conservation is a long-term national policy of China. Relevant departments also attach great importance to the energy conservation of air conditioners and related household appliances. In July 2004, three national standards were submitted for approval, namely, the limited value of energy efficiency and energy efficiency grade of room air conditioners, the limited value of functional efficiency and energy efficiency grade of unit air conditioners, and the limited value of energy efficiency and energy efficiency grade of water chillers, The three national standards were officially released on September 16 of the same year; It was officially implemented on March 1st, 2005

compressor is the heart of air conditioner and refrigerator, and it is also the main component of its power consumption. Therefore, when studying the energy conservation of air conditioner and refrigerator, the energy conservation of compressor will bear the brunt

compressor types and energy-saving countermeasures

in household air conditioners and refrigerator compressors, the main types of compressors used are scroll compressors, rolling rotor compressors and reciprocating compressors. Scroll compressor is a new type of compressor developed and used in the 1980s. Its working principle and structure are shown in Figure 1. Scroll compressor has the advantages of both reciprocating compressor and rotary compressor. It has the characteristics of small volume, light weight, low noise and vibration, simple structure and high reliability. However, due to price and other reasons, scroll compressors are still mainly used in cabinet air conditioners, and scroll compressors also occupy a large share in automotive air conditioners. The performance of eight kinds of nonlocal amplification compressors has been compared in literature. Figure 2 also shows the relationship between the pressure ratio, torque, volumetric efficiency and adiabatic efficiency of the three commonly used compressors and the rotation angle. It can be seen from Figure 2 that scroll compressor has better performance than rolling rotor compressor and reciprocating compressor in terms of its performance. Therefore, it is recognized as the third generation compressor with the most advanced technology and the ideal model of household appliances

1. Static vortex disk 2 Moving vortex disc 3 Cross slip ring 4 Spindle

5 Rack 6 Suction port 7 Exhaust port

Figure 1: structure of scroll compressor

in the research of scroll compressor, after Copland, carrier, Hitachi, Mitsubishi and other companies in the United States and Japan completed the practicality of scroll compressor in the early 1980s, the compressor research center of Xi'an Jiaotong University in China successfully developed and produced the first scroll compressor in China in 1987. After more than ten years of efforts, A series of research and design work of various scroll compressors have been completed successively, and a relatively mature design technology of scroll air conditioning refrigeration compressor has been formed

Figure 2 (a) curve of pressure ratio changing with angle

Figure 2 (b) curve of volumetric efficiency and adiabatic efficiency changing with pressure ratio

rolling rotor compressor is shown in Figure 3. It is mainly composed of cylinder, rotor, sliding plate and exhaust valve. Compared with reciprocating compressor, it is much simpler in structure, small in volume, light in weight, few parts and components, and few vulnerable parts. Compared with reciprocating compressor with the same refrigerating capacity, it can reduce the volume by 60% and the weight by 35%, The parts are reduced by about 50%. After the active research period in the 1980s, this kind of compressor has been widely used in household air conditioning equipment

Figure 3: structural diagram of rolling rotor compressor

reciprocating compressor is the first compressor used in household air conditioning and refrigeration equipment. Although the compressor has low speed, large volume and some vulnerable parts, it is also widely used in household air conditioners and refrigerators because of its mature technology, low power consumption and low cost

◆ research status and energy-saving measures of scroll compressor

the thermodynamic process of scroll compressor depends on the change of control volume, and the size of volume depends on the shear experiments of moving and stationary disks, and there are few profiles. Therefore, the study of profile has always been an important content in the energy-saving research of scroll compressor, and many structural improvements are carried out around the profile

at present, the profiles used by scroll compressors mainly include primitive involute, positive polygonal involute, segment involute, semi circular involute, Archimedean spiral, algebraic spiral, variable radius primitive involute, envelope profile and general profile. The vortex circles of the moving and stationary disks are symmetrical and asymmetric. In addition, the profile on their vortex disks also has different types, such as offset or in the center of rotation. From the working principle, it can also have single effect and double effect, that is, the vortex profile is placed on one side and two sides of the moving vortex disk. How to select and evaluate the advantages and disadvantages of so many types of profiles? Generally, the volume, efficiency, machining accuracy and resistance are considered. First, the profile with large suction volume should be selected. In order to ensure high volumetric efficiency, the length of the leakage line should be as short as possible, the pressure difference between adjacent chambers should be small, and the suction and exhaust ports should be as large as possible. Starting from the definition of effective volume and comparing different profiles, it can be seen that the effective volume ratio of circular involute is 1, quadrilateral involute is 0.9, hexagonal involute is 0.95, and segment involute is 1.023. However, considering the processing technology, circular involute is generally selected as the profile of scroll compressor. However, in the actual profile design, because the internal pressure ratio of a single profile cannot be changed arbitrarily, the interference of machining tools is easy to produce great stress at the beginning of the profile and leave a large clearance volume in the central cavity, so a single profile must be corrected. Although different profile correction methods are different, various profiles also have their own characteristics, but because the mapping relationship between these profiles and performance parameters depends too much on the profile equation, the model of each profile is too targeted and lacks versatility, so the concept of general profile is proposed later, which can carry out positive analysis and reverse correction on various profiles. Using this general profile can also greatly reduce the calculation workload. Please call us for more discounts

in the research of scroll compressor structure, the main measure is to adopt flexible mechanism. The adoption of flexible mechanism can effectively reduce leakage and friction loss, enhance the ability of scroll compressor to bear solid impurities and liquid hammer, and reduce the requirements of machining accuracy and assembly accuracy at the same time

change the wall thickness of the scroll body to improve the performance of the scroll compressor. In traditional scroll compressors, the scroll coils are of equal wall thickness. In order to achieve a high pressure ratio, multiple coils must be set, which brings complexity to the processing. The proposal of variable wall thickness can shorten the length of the scroll, reduce the residence time of the gas during compression, improve the efficiency of the compressor, and improve the area utilization coefficient at the same time

strengthen cooling and improve the performance of scroll compressor. To a certain extent, the pressure ratio of the scroll compressor is restricted by the working temperature. Iwata Coating Industry Co., Ltd. of Japan has made a breakthrough in forced cooling. They set interlayer in the moving and stationary discs, which not only cuts off the path of the heat in the working chamber directly transmitted to the moving disc bearing, improves the working life of the bearing, but also uses the interlayer for cooling, reducing the compression power consumption

use the optimization design theory of the whole machine. The performance of scroll compressor is related to many factors. In addition to the above factors, it is also affected by the processing error of profile, the processing error of stop mechanism, the configuration of cooling system and control and regulation mechanism. Therefore, it is difficult to maximize the effect of improvement limited to one aspect. It is necessary to apply the optimization design theory of the whole machine and comprehensively consider the influence of these factors to maximize the performance of the compressor

◆ energy saving measures for rolling rotor compressor

the compression and exhaust cavity of rolling rotor compressor are mainly sealed by sliding plates, so improving the machining accuracy of rotor and sliding plate, reducing circumferential and end face leakage, and improving the efficiency of compressor are the main aspects of its research. The rolling compressor has a high speed, which is generally about 3000r/min. In order to reduce leakage, the fitting clearance of each moving part is very small, mostly controlled at the micron level, which requires that each matched sliding part has a friction pair with high hardness, small friction coefficient and good matching, so it is first required to make corresponding special treatment for each friction part material. Among them, special iron castings with nickel (Ni), chromium (CR), molybdenum (MO), boron (b) and other alloy elements are used as sliding plate materials; The rotor adopts nickel, chromium and molybdenum cast iron; The eccentric shaft adopts nodular cast iron with much higher strength, toughness and fatigue resistance than ordinary cast iron; The production process of using gray cast iron for the upper and lower covers of the cylinder and the frame has achieved good results. In addition, the efficiency of the compressor will be further improved by improving the structure of the exhaust valve, increasing the thickness of the motor lamination, using silicon steel sheets with low iron loss and high magnetic flux, and improving the pre slot ratio

the rolling rotor compressor has six leakage channels, and the clearance of the leakage channels determines the efficiency, friction and wear, power consumption, processing technology and cost of the compressor. Therefore, the optimization design of the whole machine should be carried out in combination with the influence of the above factors, and the clearance values at various places should be reasonably selected

◆ energy saving measures for reciprocating compressors

reciprocating compressors were first used in the field of air conditioning and refrigeration. It was once thought that in the field of air conditioning and refrigeration, reciprocating compressors could be replaced by rotary compressors, but this process only took 1-2 seconds. Over the years, due to the continuous exploration and research in reciprocating compressors, the design and manufacturing technology has been maturing, Especially due to the low processing and manufacturing costs of this machine, reciprocating compressors still occupy a leading position in this field

the energy-saving research of reciprocating compressor mainly focuses on the frequency conversion technology. Toshiba company in Japan developed the reciprocating frequency conversion compressor as early as 1980, and the frequency conversion technology of compressor is also from reciprocating