Views:0 Author:Site Editor Publish Time: 2019-09-15 Origin:Site
The burning of a large amount of coal during winter heating in northern China has aggravated air pollution. So, is there a clean renewable energy source for winter heating? For example, what is the feasibility of solar heating? Can it be widely promoted?
Solar heating is also called solar heating. Simply put, it uses flat-plate solar collectors, vacuum solar tubes, solar heat pipes and other equipment to absorb the radiant energy of the sun, heat the water in the heat collecting equipment, and then transport the hot water to the heat. Ends, such as underfloor heating systems, radiators, etc., increase the temperature of the room.
At present, the proportion of solar heating systems in the country is less than one in a thousand. The solar heating system consists of an outdoor solar heating system and an indoor computer intelligent control system. The energy of the solar radiation is absorbed by the collector and transmitted to the water in the tube. After the water absorbs heat, the temperature rises and is present in the water tank. When the water temperature meets the heating temperature requirement, it is directly supplied to the heating. Solar radiation is affected by random conditions such as day and night, season, latitude and altitude, and random factors such as rainy weather. There are intermittent and unstable. If the indoor temperature is not enough in rainy or nighttime, auxiliary energy can be activated, such as electricity. , natural gas, etc. to heat the water in the water tank. "If the proportion of solar heating efficiency is less than 50%, it can basically not be called solar heating, but it can only be said to be solar-assisted heating. The current efficiency is generally higher than 70%."
Consumers of solar heating can be divided into residential customers and unit users. Residential customers are divided into urban residential, rural residential and villa-style residential; unit users are divided into workshops, office buildings, schools, hospitals, etc. When designing a solar heating system, it is necessary to consider the area, project type (such as villa, factory, school), house layout and structure (brick mix, steel structure, number of floors, floor height, etc.), water source (either tap water or well water), Auxiliary energy (electricity, gas, biomass, etc.), temperature and heating time requirements.
Figure 1 Solar heating uses energy harvesting equipment to absorb solar radiation energy, heat the water in the heat collecting equipment, and deliver the hot water to the end of the heat to raise the temperature of the room.
In the design of solar heating systems, many people do not understand the difference between solar heating and solar hot water systems (providing domestic hot water for residential buildings). For example, solar heating uses a circulation pump cycle command, while solar water heating is a pressure start command for the faucet. When the solar hot water command is placed on the solar heating system, it will not work, or it will be damaged after several months of frequent work, and the system will be scrapped.
There are also many solar heating practitioners who unwittingly walk into a misunderstanding, thinking that the higher the hot water temperature, the better, but it is not. The hot water temperature is defined in the range of 40 to 60 degrees Celsius. If the temperature is low, the heating effect may be poor. If the temperature is high, the heating system and the heat dissipation system may be accelerated. Some collectors can heat water to more than 100 degrees Celsius and become water vapor, but this may cause the internal pressure of the system to be too high, increasing the occurrence of failure. Some experts said that the choice of collectors should take into account the heat, heat loss and effective utilization, not to say that the more expensive, the better, not the faster the better. The choice of auxiliary energy should also consider the user's use. Convenience and cost, some places are suitable for electricity, while some houses can only use gas, and some rural users choose biogas or biomass boilers. The cost, later cost, life and failure rate of equipment will affect solar heating. effectiveness.
The core of solar heating technology lies in the optimal design of computer intelligent control systems and complete systems. The computer intelligent control system is responsible for the integrated management of solar collectors, auxiliary energy, water tanks and circulation systems, and has the greatest effect on improving solar energy utilization and reducing auxiliary energy consumption.
Figure 2 The choice of collectors should take into account the heat, heat loss and effective utilization, not the more expensive or the faster the heat, the better.
How to judge the quality of solar heating system? It is more difficult for ordinary consumers to identify themselves. In order to protect their own rights and interests, it is best to find a company that specializes in solar heating and sign a warranty contract for more than 2 years. As for the system, the following indicators can be seen generally.
The temperature that the user is required to reach before the purchase is consistent with the temperature that the seller promises to be able to achieve according to the purchased configuration, and can be stably reached in the coldest winter or rainy days after installation. However, consumers need to be wary of the fact that some people in the market use solar water heating projects to mix fish and dress up as "solar heating."
Whether the auxiliary energy is energy-saving, how much energy is saved, and whether it is perfectly combined with solar energy is the basis for the success of the heating system. From a practical point of view, the solar heating system consumes 2000 to 3000 kWh in a heating season, which is the power consumption recognized by most users.
Designers need to know in detail the local climate, the nature of different structures, different heating habits, and reasonable planning and design through computer language, through the combination of variables and constants, to achieve low failure, high security.
The total heat of solar heating is much larger than that of solar hot water, so in the case that most of the heat is transferred to the heating, it is also necessary to ensure the user's domestic hot water, which is also a factor that must be considered.
The one-time investment in solar heating is similar to central heating, but the later cost is lower than central heating, which is significantly lower than electric boilers and fuel gas boilers. In large-scale applications in residential quarters, schools, and office buildings, the initial investment in solar heating is about 24,000 to 30,000 yuan per 100 square meters. The later expenses are mainly from auxiliary energy. The electricity cost for a heating season (4 months) is about 1200-1500 yuan per 100 square meters. Regardless of the size of the heating, you can compare the primary and late costs with various heating methods. In general, the life of boilers and air conditioners is 5-8 years. If you use heating and cooling air conditioners for heating, a heating season will cost about 5,500 yuan.
The solar heating system has a life span of about 15 years and can recover costs within 3 to 6 years. The price advantage is more obvious – especially in areas with large government subsidies.
At present, the main obstacle to the promotion of solar heating is that the price in the early stage is relatively high, and in addition, the public's awareness is relatively low. Government departments at all levels who have the power to make purchasing decisions often do not know what brand is reliable in the market, and there is no unified and effective monitoring and evaluation standard. "Some companies' products are still available in the first year, and they are scrapped in the second year, mainly due to design and quality issues, but often such projects leave the local government and users with a bad impression that solar heating is not reliable."
The environmental benefits of solar heating are very good, but the installation of solar heating projects can not be blindly promoted. Not all houses are suitable for solar heating, and should be adapted to local conditions. Some houses that are particularly cold and have poor insulation properties or have problems with the HVAC system are best not to do solar heating. Because these houses use other heating methods, it is difficult to achieve the user's satisfactory heating effect.
It is understood that some sales agents do not inform the manufacturers of this information in advance, even this poorly insulated house is also used to engage in solar heating. In the end, if the expected design room temperature is not reached, it will cause a dispute. It is also not advisable to use a low configuration to do large-area heating. Some business people reduce the allocation of solar energy and auxiliary energy because of low user budget. Some users can reduce the heating cost by reducing the cost, resulting in difficulty in inspection and acceptance, difficulty in recovering project funds, complaints from users or requests for returns. problem.
"This is a problem that should be paid attention to before the construction of the project." Experts reminded that employees or agents must be exaggerated in order to accept orders, and finally leave a bunch of unfinished projects, resulting in returns claims and other issues. If the manufacturer does not have the corresponding technology and excellent products, do not blindly order. In addition, manufacturers and agents must not be confused by some so-called inventions and irresponsible experts, to put some products that are not effective to the market, so as not to misunderstand for a moment.
In the current solar heating market, some manufacturers and agents only make a fuss about the obvious system configuration of the number of solar collectors, the size of the water tank, and the power of electric heating. There is no breakthrough in the technical bottleneck, and the result is "imitation of others every year. The odds of the project's losses. At present, there are only a few domestic enterprises and agents with relatively mature solar heating technology, which meets the basic requirements of national heating: 18 degrees Celsius and above in the whole climate of winter, the user can accept the cost in the early and late period, and the operation failure rate is low. At 1%, it can be mass-produced, sold, and installed. Therefore, consumers are reminded that if they choose a good solar heating product, they must find those qualified installation examples that have qualifications and have more than two years and more, and must have at least two enterprises and products that have been tested in the heating season.
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