What Is Solar Air Conditioning?

The new solar hybrid superconducting air conditioner uses solar energy and renewable biomass fuels as its main energy source during heating. It is a truly green heating method. During the refrigeration, a small amount of electric energy is used to utilize the low temperature of the ground source, and the superconducting energy transmission system is used to directly cool, so as to achieve the most reasonable energy-saving refrigeration effect. Traditional air coolers cannot eliminate nasty side effects-long-term consumption of large amounts of energy, inefficient use of energy, and accelerated global warming. It would be great if people could successfully use sunlight to cool homes or offices-it would not consume a lot of hard-to-renew energy and would not release too much carbon dioxide during the cooling process.

In the context of global warming, solar energy, as an outstanding representative of new energy, has been favored by countries around the world. Under the trend of low-carbon energy saving, solar energy based on photothermal technology has been applied to various industries, and the energy structure is continuously improved. With the support of the state's policy on the solar energy industry, various manufacturing and application fields that use solar energy technology are experiencing vigorous business opportunities, and a series of solar energy products are gradually entering people's lives. Nowadays, major manufacturers have introduced solar air conditioners, making solar air conditioners, a new type of air conditioner unit that is generally considered to have broad prospects but is difficult to market in the short term, once again attracted the attention of the industry.

In the hot summer, the power consumption of air conditioners accounts for almost one third of the power consumption of the entire power system.

The heart of the system is a motor called "Schukey"

Solar air conditioning system

In order to put solar absorption air-conditioning technology into practical application, according to the task of the National Science and Technology Plan of the Ninth Five-Year Plan, Beijing Solar Energy Research Institute completed a set of China's largest solar energy absorption air-conditioning and heating demonstration system in September 1999. .

Solar air conditioners have good seasonal adaptability, that is, the cooling capacity of the system increases with the increase of solar radiant energy, which is exactly in line with the urgent requirements of air conditioners in summer.

Traditional compression refrigerators use Freon as a medium, which has a great damaging effect on the atmosphere, while refrigerators use non-toxic and harmless water or lithium bromide as a medium, which is very beneficial to protecting the environment;

Solar air conditioning systems can combine summer cooling, winter heating, and hot water supply in other seasons, which significantly improves the utilization and economic efficiency of solar systems.

Solar air-conditioning systems can take advantage of the combined advantages of summer cooling, winter heating, and hot water supply throughout the year, and will definitely achieve significant economic, social, and environmental benefits, and have broad prospects for popularization and application. ^[2]

While emphasizing the advantages of solar air conditioners, we should also see its limitations, so pay attention to solving these problems in the process of promotion and application:

(1) Although solar air conditioners have begun to enter the practical stage, and the number of users who wish to use solar air conditioners continues to increase, most of the products that have been commercialized are large-scale lithium bromide refrigerators, which are only suitable for central air conditioning units. In this regard, the air-conditioning and refrigeration industry is actively researching and developing various small lithium bromide or ammonia-water absorption refrigerators to gradually enter the home with solar collectors;

(2) Although solar air conditioners can make free use of solar energy resources, due to the low solar irradiance under natural conditions, the ratio of the collector's lighting area to the construction area of the air conditioner is limited. Nowadays, it is only applicable to those with few layers. building. In this regard, we are stepping up the development of vacuum tube collectors that can generate water vapor in order to combine with vapor-type absorption refrigerators to further increase the ratio of the collectors to the building area of air conditioners;

(3) Although solar air conditioners can greatly reduce the consumption of conventional energy and greatly reduce operating costs, the initial investment of the system is still relatively high today, which is only suitable for limited wealthy users. To this end, we are persistently reducing the cost of existing vacuum tube collectors, so that more and more units and homes have the economic affordability of using solar air conditioners.

We believe that the solar absorption air conditioning system can take advantage of the comprehensive advantages of summer cooling, winter heating, and hot water supply throughout the year, and will definitely achieve significant economic, social, and environmental benefits, and have broad prospects for popularization and application.

Theoretically, there are two ways to realize solar air conditioners. One is to first realize light-electric conversion, and then use electricity to drive conventional compression refrigerators for cooling; the other is to use solar thermal energy for cooling. For the former, due to the high price of high-power solar power generation technology, solar air-conditioning technology generally refers to heat-driven air-conditioning technology. Of course, in a broad sense, solar air-conditioning technology also includes geothermal drive and underground cold-source air-conditioning technology.

Due to technology, cost and other reasons, solar air conditioners generally use absorption and adsorption refrigeration technologies. Absorption refrigeration technology is a technology that uses the absorption and evaporation characteristics of an absorbent to perform refrigeration. According to the different absorbents, it is divided into two types: ammonia-water absorption refrigeration and lithium bromide-water absorption refrigeration. Adsorption refrigeration technology uses the adsorption of solid adsorbents on refrigerants for refrigeration. Commonly used are molecular sieve-water, activated carbon-methanol adsorption refrigeration. Both refrigeration technologies do not use Freon, which can avoid the damaging effect on the ozone layer, which is of special significance; and they use lower-level energy, which has bright prospects in energy saving and environmental protection. In addition, the adsorption refrigeration system has low operating costs (or no operating costs), no moving parts, long life and no noise, and is widely used in special fields such as aviation and aerospace.

For solar refrigeration technology, because of the efficiency of the collector, it is necessary to use a relatively low heat source temperature. Therefore, the solar-powered refrigerator has a problem of low efficiency. As a result, from the perspective of the corresponding cost allocation of heat collectors, refrigerators, etc., how much should the heat collection temperature, cold water temperature and cooling water temperature be in order to establish a most economical and reasonable solar air-conditioning system, it remains to be seen. Problem solved. In addition, due to the time-efficiency of solar energy collection, heat storage technology must also be well resolved. A better heat storage system can compensate for the irreversibility and discontinuity of solar energy. ^[3]

1. Initial stage (not in the 1970s and early 1980s)

In China, the research on solar refrigeration and air conditioning can be traced back to the late 1970s after the National Solar Conference was held in Guiyang in 1975. After the Middle East oil crisis in 1974, many scientific research institutions, universities, and enterprises invested manpower and material resources to develop solar refrigeration (air-conditioning) machines, most of which were small-scale absorption refrigeration test prototypes. For example, the continuous ammonia-water absorption solar ice maker developed by Tianjin University in 1975 can produce 5.4kg of ice per day. Developed a 1.5m2 flat-type intermittent solar ice maker for Beijing Normal University (now Capital Normal University, etc.) in 1977, which can make 6.8-8kg of ice per day. In 1979, it developed an 8m ² flat-type automatic tracking continuous solar refrigerator. cabinet. Huazhong Institute of Technology (now Huazhong University of Science and Technology) has developed a small solar refrigeration device with a lighting area of 1.5m2, a refrigerator volume of 70 liters, and ammonia-water as a working medium pair, which can maintain the refrigerator at 0 ° C for about 10 hours. During this period, more than 20 units have carried out work and accumulated valuable experience.

2. Persistence stage (mid-to-late 1980s to early 90s)

Later, because there were still many technical problems that could not be solved at the time, the solar air-conditioning project was not supported because it was difficult to see the results. The research team and scale were greatly reduced. Only a few units still adhered to basic research and prototype tests. Going through a very difficult time. During this period, the Guangzhou Institute of Energy of the Chinese Academy of Sciences received funding from the Hong Kong Jue Foundation, insisted on the research of solar air-conditioning systems and solar refrigerators, and made important progress.

In 1987, the Guangzhou Institute of Energy Conversion of the Chinese Academy of Sciences and the Hong Kong Polytechnic University cooperated to build a set of scientific research and practical demonstration solar air conditioning and hot water integrated systems in Shenzhen. 80m ² adopts three kinds of medium temperature collectors, including straight-through true main collectors, heat pipe vacuum tube collectors and V-shaped heat insulation film flat plate collectors. A 2-ton single-stage desalination absorption refrigerator manufactured by Lianghe Japan Yazaki Corporation is used.

In order to adapt to the utilization of solar energy, the Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences began to develop and succeed in a new type of hot water two-stage absorption refrigerator since 1982. This new type of refrigerator has two significant characteristics. The required heat source temperature is low, and it can run stably in the range above 65 ° C. The second is that the temperature difference of the heat source is large, which is 12-24 ° C (varies with the heat source temperature).

3. Practical stage (during the Ninth Five-Year Plan)

Until the "Ninth Five-Year Plan" period, conditions for solar air conditioning have matured in various aspects. The State Science and Technology Commission (now the Ministry of Science and Technology) listed "solar air conditioning" as a key scientific and technological project, and plans to build a demonstration system to promote the promotion and application of solar air conditioning. . The solar air-conditioning project has ushered in the second spring, and the technical level of solar air-conditioning has also risen to a new level. The Chinese Academy of Sciences Guangzhou Energy Institute and Beijing Solar Energy Research Institute have undertaken this task, and plan to build a large-scale practical solar air-conditioning system in the south and the north. ^[4]

Research and development direction of solar air conditioner

1. Industrialization

The completion of the solar energy air-conditioning practical demonstration system proves that solar energy air-conditioning is technically feasible and shows certain benefits economically. The potential market is huge and should be developed towards industrialization. But to achieve the industrialization goal, there is still much work to do, such as: computer design software for solar air-conditioning systems; commercialization and industrialization of refrigerators; unified supporting equipment and parts; formulation of technical standards for products (systems); Develop new markets.

2.Research and development of new branches

Solar air conditioning systems currently use mature desalination absorption refrigeration technology. Due to cost and other reasons, the refrigerator should not be made too small. Therefore, the solar air-conditioning system using this technology is suitable for central air-conditioning and centralized heating methods, and the system needs to have a certain scale. However, the market has greater demand for small, domestic solar air conditioners. Facts and experience tell us that only products that meet the needs of millions of households can form a large-scale industry. Therefore, it is necessary to research and develop new methods and technologies for small solar air conditioners.

3.Heat-electricity-cold supply system for buildings

Building energy consumption is a large energy consumer, of which more than half is used for lighting, heating and air conditioning. The application of solar energy to buildings can not only save energy, but more importantly, protect the environment. The use of solar power, heating, cooling, and lighting to finally realize the so-called green energy house is a hot research topic in many developed countries in the world. It will also be a multi-disciplinary interdisciplinary with wide application and high demand in the 21st century. Comprehensive topics. This is a compelling development trend in the use of solar energy.

With the development of our country's economy and the improvement of people's living standards, people's requirements for living environment are getting higher and higher. Heating and air conditioning are already necessary facilities for buildings. On the other hand, due to the continuous exploitation and use of conventional energy, its reserves will continue to decrease, and the problem of environmental pollution is becoming increasingly serious. Therefore, the use of solar energy for cooling and heating can not only save electricity and conventional energy, but is also of great significance for environmental protection. ^[4]