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Analysis of solar air-conditioning works

In Electronic Infomation Category: A | on April 18,2011

So-called solar cooling, is the use of solar collectors for the absorption chiller to provide the required generator heat medium water. The higher the heat medium water temperature, the refrigerator coefficient of performance (also known as COP) the higher the cooling efficiency of air-conditioning system that is also higher. For example, if the heat medium water temperature about 60 , the chiller COP of about 0 to 40; if the heat medium water temperature about 90 , the chiller COP of about 0 to 70; if the heat medium water temperature about 120 , the refrigerator COP of up to 110 or more.

Proved, the use of heat pipe vacuum tube collectors with lithium bromide absorption chiller combination of solar air conditioning technology program is successful, it is solar thermal technology has opened up a new application areas.

1. Basic principle

Solar absorption air conditioning system consists of solar collectors and TC74VHC32FT datasheet and absorption chillers of two parts.

1.1 absorption refrigeration works

Absorption refrigeration is the use of two substances composed of binary solution as working fluid for the. These two substances have different under the same pressure the boiling point, high boiling point component which as absorbent, low boiling point component is called refrigerant. Commonly used absorbent - refrigerant combination of two kinds: one is lithium bromide - water, usually for large central air-conditioning; the other is water - ammonia, usually applied to small air conditioning.

Mainly by the absorption chiller generator, condenser, evaporator and TC74VHC32FT price and absorber components.

This paper, an example of lithium bromide absorption chiller. In the refrigerator is running, when the lithium bromide solution in the generator heated by the heat medium water, the water continued vaporization of the solution; water vapor into the condenser, condensed by cooling water after cooling; With the continuous evaporation of water, generators rising concentration within, into the absorber; when the condenser water through the throttle into the evaporator, the rapid expansion and TC74VHC32FT suppliers and vaporization and vaporization process in the evaporator refrigerant absorbs heat from the water, so as to achieve cooling The purpose of refrigeration; in this process, low temperature water vapor into the absorber, is absorbed inside the absorption of concentrated lithium bromide solution, the solution concentration gradually reduced from the solution pumped back to the generator, to complete the cycle.

1.2 solar absorption air-conditioning works

The so-called solar absorption refrigeration, is the use of solar collectors for the absorption chiller to provide the required generator heat medium water. The higher the heat medium water temperature, the refrigerator coefficient of performance (also known as COP) the higher the cooling efficiency of air-conditioning system that is also higher. For example, if the heat medium water temperature about 60 , the chiller COP of about 0 40; if the heat medium water temperature about 90 , the chiller COP of about 0 70; if the heat medium water temperature about 120 , the refrigerator COP up to 1 10 or more.

Conventional absorption air conditioning system includes absorption chillers, air-conditioning box (or coil), boiler and other parts, and solar absorption air-conditioning system is on this basis, to increase solar collector, storage tank and automatic control system.

In the summer, the hot water heated by the collector into the tank first, when the water temperature reaches a certain value, the storage tank to provide heat to medium water chiller; from the refrigerator out and have hot water back into the cooling storage tanks, then into the high temperature hot water heating collector; refrigerator water produced by leading air conditioning refrigerant tank, in order to achieve the purpose of refrigeration and air conditioning. When insufficient to provide solar water heating medium temperature, heat added by the auxiliary boilers.

In the winter, heating the same collector for hot water first into the tank when the water temperature reaches a certain value, the storage tank to provide hot water directly to the air box to achieve the purpose of heating the heating. When the solar energy can not meet the requirements, but also by auxiliary boiler to add heat.

In non-air-heating season, as long as the collector for hot water heating tank with direct access to the life of the heat exchanger, storage tank can be heated gradually in the cold water for use.

2. Air conditioning and heating systems integrated model

To the solar absorption air conditioning technology into practical applications, according to "Ninth Five-Year" national research programs the task, the Beijing Solar Energy Research Institute in September 1999 completed a Chinas largest solar absorption air-conditioning and heating integrated demonstration system (see press questions photo).

2.1 installation site profile

Solar air conditioning demonstration system built in Shandong province ^ ^ ^ Hill City. ^ ^ ^ Hill City, located in the southeast of Shandong Peninsula, Yantai, north, west of Qingdao, south Yellow Sea. The region has good solar resources, the annual average amount of solar radiation at 17 3MJ/m2. Local summer maximum temperature 33 1 , winter minimum temperature -7 8 , respectively, in summer and winter cooling and heating requirements, so is the installation of suitable sites for solar air conditioning system.

^ ^ ^ Hill, Silver Beach Resort using the natural conditions of the region, to develop tourism, is to establish the "new energy science park in China." Plans to build science parks, including wind Museum, Museum of solar energy, etc., 8 Hall, Council Chamber. Solar air conditioning system to build the solar parks in the science museum.

Where people can not only visit the solar science exhibits, an increase of solar science knowledge and understanding of the latest solar technology, and entertainment at the same time to visit and personally experience created by a solar air conditioning and heating comfort.

2.2 The main technical performance

New solar air conditioning system by the heat pipe vacuum tube collector, lithium bromide absorption chiller, thermal storage tanks, cold storage tanks, thermal storage tank used in daily life, circulating pumps, cooling towers, air handling units, auxiliary oil-fired boiler and automatic control systems and other components. System installation is complete, after winter, spring and summer quarters to run and test, to Table 1 of the main technical performance.

2.3 System Design Features

(1) solar energy and architecture combine

The overall design of the solar energy even if the museum building is handsome in appearance, novel and unique, but also to meet the requirements of the collector installation. According to this principle, the south facades of buildings with large pitched roof structure, an inclined plane is much greater than the area can be arranged more collector; two collectors arranged in an inclined plane around the block without having to consider problem, but also very beautiful shape. Inclined to take the roof angle 35 , and the local latitude close to fully conducive to the role of the collector.

(2) vacuum tube collector heat pipe to improve the efficiency of refrigeration and heating

Heat pipe vacuum tube solar collector is the Beijing Institute of a major scientific and technological achievements, with high efficiency, resistance to freezing, start fast, good insulation, high pressure, thermal shock, running can be * many other advantages, solar air conditioning system is composed of an important high-performance components. Heat pipe vacuum tube collector can provide efficient lithium bromide chiller 88 of heat medium water, thereby enhancing the cooling efficiency of the system; this collector cold winter in the north can work effectively for building heating.

(3) the size of the two thermal storage tanks every day to speed up the process of cooling or heating

According to changes in solar irradiance day the inherent characteristics of thermal storage tank can not only make the system stable operation, but also the peak of the solar irradiance excess energy stored in the form of hot water. The system of solar air-conditioning systems and the general difference is set large and small two thermal storage tanks. Small thermal storage tank to ensure the system is mainly used for quick start. The results show that in the summer and winter sunny morning, a small reservoir of hot water inside the water temperature can reach 88 , respectively, and 60 , in order to meet the cooling and heating requirements.

(4) a dedicated cold storage tank system reduces heat loss Although the thermal storage tank

can store energy, but its capacity is limited after all. The system is specifically designed a cold storage tank. Abundant solar radiation during the day the case, the refrigerant can be generated by Refrigerator water stored in cold storage box, and its advantage is that this situation is clearly better than the system heat loss to heat water stored in the storage medium hot water tank in much lower, because the summer water temperature of the refrigerant temperature and the temperature difference between the heat medium to be significantly smaller than the water temperature and the temperature difference between ambient temperature.

(5) auxiliary boiler system around the clock to run

Run all the solar system are inevitably affected by climate conditions. To enable the system to play all-weather air-conditioning, heating function, supporting the conventional energy sources is essential. The solar air-conditioning system uses an auxiliary fuel hot water boiler, less the amount of solar radiation during the day and night to continue to use cold or hot, you can then start the auxiliary boiler to ensure a sustained and steady running.

(6) system operating conditions and can automatically switch between the control

Part in the use of solar energy replace conventional energy system, the system starts, energy storage and switching between solar and conventional energy sources such as the automation features are particularly important; In addition, the system has set up several storage tanks, how to automatically enable the different conditions of different water tank, take a different line, is the key to the normal operation of the system; Furthermore, the solar system should be * automatically to prevent overheating and to solve the problem anti-freeze. Therefore, we designed a solar air conditioning system for a security can be *, fully functional control system.

3. Promotion prospects

Proved, the use of heat pipe vacuum tube collectors with lithium bromide absorption chiller combination of solar air conditioning technology program is successful, it is solar thermal technology has opened up a new application areas.

Solar absorption air-conditioning compared with conventional air-conditioning, with the following three distinct advantages:

(1) adaptability of solar air-conditioning season, that is, the system cooling capacity with the increase of solar radiation, which coincided with the urgent need for air conditioning in summer uniform requirement;

(2) conventional compression chillers with Freon as the medium, it has great atmosphere and damaging effects, and absorption chillers with non-toxic, harmless lithium bromide as the medium, it is very beneficial to protect the environment ;

(3) the same set of solar absorption air-conditioning system can be summer cooling and winter heating and provide hot water in other seasons combined, significantly improve the utilization of solar energy systems and the economy.

Course, everything Yao Yi Fen Wei Er . We emphasize the advantages of solar energy air-conditioning, we should also see its existing limitations, and therefore attention in the application process to address these issues:

(1) Although the solar air conditioning entered the practical stage, the users want to use solar energy air-conditioning increased, but the commercialization of the products has achieved a large lithium bromide chillers are only applicable to central air conditioning units. In this regard, air conditioning and refrigeration industry is actively developing a variety of small lithium bromide or ammonia - water absorption chiller, in order to complete step by step with the solar collectors into the home;

(2) Although the solar air conditioning solar energy resources can be used free of charge, but under natural conditions is not high solar irradiance, the light collector area and the ratio of air-conditioned building area is limited, the current rise is not only applicable to number of buildings. In this regard, we are stepping up research to produce steam vacuum tube collector for absorption chillers with vapor-type combination of collector and air conditioning to further enhance the ratio of floor area;

(3) Although the conventional solar air conditioning can greatly reduce energy consumption, significantly reduce operating costs, but the current system, the initial investment is still high, only a limited number of affluent users. To this end, we are constantly reducing the cost of the existing vacuum tube collectors, more and more families with the use of solar energy units and affordability of air conditioning.

Recent years, the Earths surface temperature rise, and people are more and more intense summer air conditioning requirements, installation of air conditioning has become an area of ??spending most of the wave. We believe that solar absorption air-conditioning system can play in summer cooling and winter heating, hot water year-round comprehensive advantages, will achieve significant economic, social and environmental benefits, has broad application prospects.

Theory, the realization of solar air-conditioning in two ways, first, first, an optical - electrical conversion, and then conventional power-driven compression chillers for cooling; second is to use the suns heat drives the refrigerant. For the former, due to the high power price of solar power technology, the current availability is poor. Therefore, solar air conditioning technology generally refers to the heat-driven air-conditioning technology. Of course, solar air conditioning technology in the broad sense also includes the underground geothermal cooling source drive and air conditioning technology.

Due to technical, cost and other reasons, solar air conditioning generally use the absorption and adsorption refrigeration technology. Absorption refrigeration technology is the use of absorbent characteristics of the absorption and evaporation cooling technology, according to the different absorbent, into ammonia - water and lithium bromide absorption chiller - water absorption refrigeration two. Adsorption refrigeration technology is the use of solid sorbent on adsorption of refrigerant to refrigeration, commonly used molecular sieve - water, activated carbon - methanol adsorption refrigeration. Not use freon refrigeration technology both to avoid damaging the ozone layer, has a special meaning; and both a lower level of energy, energy saving and environmental protection has a bright future. In addition, the adsorption refrigeration system operation cost is low (or no running costs), with no moving parts, long life, no noise, especially in the aviation, aerospace, and other special areas of wider application.

For solar cooling technology, because to take care of the efficiency of the collector to the heat source had to use a relatively low temperature. Therefore, the existence of solar-driven refrigerator problem of low efficiency. Followed from the collector, refrigerator and other associated costs allocation, collector temperature, water temperature and cooling water temperature should be as much of each to create one of the most economical solar air conditioning system, is yet to be solved. In addition, because there is time to collect solar energy issues, storage technology must also be a good solution, a good solar heat storage system can compensate for the non-* and intermittent.

4. Solar air conditioning technology advantages

Currently, most of the use of air conditioning technology is a kind of energy as a driving force to be absorbed heat out of the room outside the circulatory system. This air-conditioned indoor heat is collected, the release into the atmosphere, further enhanced the atmosphere of high temperature, the more filled with empty, the city will be higher atmospheric temperature, the heat island effect will be more intense. In addition, the refrigeration cycle freon and other media, the widespread use of fluoride, resulting in the destruction of atmospheric ozone layer, deterioration of the ecological environment is also well known. In recent years, replacing the working medium of the new CFC air-conditioning (whether pollution of the environment, to be the long-term test) already on the market. But energy remains a serious problem, growing tension in the worlds energy today, the use of more energy-efficient air-conditioning system is the common human needs.

Use of solar energy air-conditioning system, which is an attractive solar radiation is more intense when the ambient temperature of the higher peoples lives the more we need air-conditioning, this time, solar air-conditioning cooling capacity will be. This is the ideal state of harmony between man and nature. The result of the use of solar air-conditioning, not only to create a pleasant indoor temperature, but also reduce the atmospheric temperature, but also weakened the urban heat island effect. Is preferable, which saves energy, does not use the destruction of Freon and other harmful substances in the atmosphere, is truly green air conditioning.

5. Solar air conditioning technology prospects

To the air conditioning industry in China, the air conditioner market is in a stage of development and perfection, at present, the familys air conditioner cities only 20% popularity, the market potential is huge. With the substantial increase in peoples living standard, air conditioner has become an essential household appliances, and now, hindered air into the home energy consumption and the main contradiction is the price factor. In addition, the current mass production of large commercial central air conditioning and home wall, vertical air-conditioning is not suitable for some high-end residential, need to be a small residential central air conditioning to fill this gap. Solar air conditioning from the features and technical characteristics point of view, solar air conditioning is best suited to resolve these contradictions and applications, so the current demand for solar air-conditioning industry, the development and application of air conditioning technology has brought a rare opportunity.

After several years of development, solar air conditioning technology has begun to enter the practical stage. Now, technological progress and economic development for energy and the environment put forward higher requirements, I believe in the government and the support of the community, closely based on the mature large solar water heater market, solar air conditioning technology must have broad application prospects .

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