Views:0 Author:Site Editor Publish Time: 2019-09-03 Origin:Site
As the source of the earth, solar energy is a clean and renewable resource. The use of solar energy to achieve building heating is in line with the trend of transforming the fossil energy system into a low-carbon energy system, in line with the objective requirements of the new rural construction, and is conducive to protecting the green water and blue sky of the motherland.
Solar heating has advantages in resource endowment and industrial base in China, and has been at the forefront of the world in solar water heating technology and market applications. However, there is a difference between the solar domestic hot water system and the solar heating and hot water system. Generally, the domestic hot water does not need to be continuously supplied, and the general heating system must be continuously supplied and stable and reliable, and the heat dissipation method at the end of the room should be considered to be reasonably determined. Stable system hot water temperature. Due to the large intermittent and unstable solar energy, the solar energy alone cannot meet the heating demand of a large amount of heat, and must be integrated with other stable and reliable heat sources. This requires the solar heating and hot water system to have equipment that is not available in the domestic hot water system, so that the system can operate efficiently and stably. In addition, control devices that coordinate the proper operation of these devices are required. Therefore, the system is complicated, which inevitably increases the difficulty and cost of the system. In addition, equipment corrosion, run-and-leak and winter use freeze problems need to be resolved.
Rural household heating is the key and difficult point of promoting clean heating and implementing loose coal treatment. It is urgent to find a heating method with high cost performance, good energy saving and reliable operation to solve the problem of rural household heating.
To meet the strong demand in this market, we have developed this solar + photovoltaic thermal storage household heating system (as shown in the figure 1).
The solar collector method of the system breaks the routine of using water as a medium, and adopts the technical means of directly heating the air by solar light and heat, and generates hot air to be sent to the room to heat the room to achieve the purpose of heating.
1. There is hot air in the sun, and the system reacts quickly.
2. There is no secondary conversion loss of energy and high efficiency.
3. There is no equipment corrosion and winter freezing.
At present, solar air heat collection is roughly divided into flat type, inner tube guide type vacuum tube air collection heat and all glass double vacuum heat pipe air collection, etc. Most of them borrow the experience and devices of solar water heating system, and solar light heat. The application of heated air is not very tacit. Compared with water, the thermal conductivity of air is small, resulting in much less heat transfer between air and heat sink than water; the density of air itself is low, so the heat flow of the collector is large enough to get the heat required. Enhancing heat transfer and ensuring adequate ventilation, while maintaining small fan power under this premise, has been a key issue in the development of high performance solar air collectors.
We designed a “hole tube solar air collector” for solar air collector heating, and its working principle is as shown in the figure 2:
The inner tube is composed of an inner tube and an outer tube. The outer tube is a light-transmissive glass tube. The inner tube is coated with a solar heat absorbing membrane layer, and a plurality of penetrating vent holes are provided. The hollow tube body is open at one end and is set inside the outer glass tube. The solar collector is composed of a plurality of such heat collecting tubes and inlet and outlet air headers, and the heat collecting tubes are located in the middle and are directly connected to the two headers. The cold air enters the inlet air inlet box, passes through the annular cavity between the inner and outer tubes of each heat collecting tube, penetrates into the tube through the vent hole of the inner tube, fully exchanges the solar heat absorbed by the tube body, and is drawn by the fan to concentrate on the air outlet. The box forms hot air to the room.
The heat pipe solar collector can make the heat exchange between the air and the heat absorbing body fully and instantly take away the absorbed solar heat, and is sent to the room for effective application. The fan consumes less power and the system has higher heat collecting efficiency.
Due to the intermittent and discontinuous solar energy, solar heating has the difference between the daylight supply and the nighttime heat demand, that is, the inconsistency between energy supply and energy use. The technical way to effectively solve this problem is to use heat storage. technology. The indoor part of the system adopts a low-temperature phase-change heat storage type carbon fiber electric heater device to coordinate the mismatch between time and intensity of heat energy supply and demand, and turn unstable solar energy into stable hot air output to achieve continuous heating and energy saving, and improve the sun. The contribution rate of energy.
When the sun is full during the day, the hot air generated by the solar collector passes through the heat storage heater to provide heat to the room for heating with a relatively stable medium phase transition temperature. On the other hand, the remaining heat is stored in the device during solar radiation. Reduce to the time after the sun sets and release the stored heat. The process is solar hot air heating and light heat storage heating period; after the start of the valley electricity time, the indoor heat storage electric heater automatically switches to the carbon fiber electric heating state, the heat generated by the cheap valley electricity is used for heating, and at the same time, the excess heat is stored. Save, release the stored heat during the period before the peak time of the valley electricity is sufficient. This process is a complementary electric heating and electric heat storage heating period, which achieves the purpose of continuous heating for 24 hours.
The system operates in two parts: one is solar hot air and light heat storage; the other is valley electric heating and electric heat storage heating.
For the system design of the first part, the heat collecting area of the collector is determined according to the daily average solar radiation amount of the local heating season and the total heat required for the heating room. In principle, the effective heat collection of the collector meets the heating demand of the room. That is to say, the free solar energy is completely utilized during this period, and the user does not increase the running cost of the valuable energy consumption.
The other part, which is also the main energy-consuming part of the whole system, appears in the period from 22:00 to 10:00 every day, mostly at night, allowing for a reasonable reduction in heating temperature. Taking the room temperature of 12 ° C as an example, in the room temperature state maintained during the day, a unit heat load of 50 an be provided to meet the requirements. According to the rural single room area of 25, carbon fiber electrothermal conversion efficiency of 98% calculation, the need for 54kJ of heat, supporting 1800W electric heating power, the need for electricity consumption of 20kW·h, different regions of the valley electricity subsidy policy (according to most areas 0.1 yuan / kW · h ), the total solar energy + photoelectric heat storage household heating system has a total operating cost of 2 yuan per day, a conventional heating period of 100 days, and an annual operating cost of about 200 yuan, reflecting the remarkable economic and energy-saving performance of the system.
In summary, the Sunpower solar&photoelectric heat storage household heating system has a simple structure, low cost, remarkable energy conservation, and can be tolerated by residents. It has the characteristics of being practical and suitable for reproduction and promotion. The promotion and application of this system will play an active role in the blue sky defense battle of clean energy instead of coal-fired heating.
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