Many knowledge of the use of light energy
How the solar energy resources in Beijing are distributed According to the detection and statistics of the meteorological department, the daily average of the total radiation amount on the monthly horizontal surface in Beijing in 1976.
Adding the average daily irradiance for 12 months, divided by 12, gives an average annual daily exposure of 2,14,424 kilojoules per metre.
The numbers in Table 1 are drawn with the coordinate paper as the curve of Fig. 1, the abscissa is the month, and the ordinate is the irradiation amount.
It can be seen from the curve that the highest irradiance month is May, the daily average irradiance is 2,23,950 kJ per metre, the lowest month is December, and the average daily irradiance is 2,380,380 kJ per metre.
How the solar sunshine situation in Beijing has been tested by the meteorological department, and the average actual sunshine hours in each month of the Beijing area (20 years) is counted.
Table 2 The average actual sunshine hours in each month of Beijing area is shown in Table 2. The average annual sunshine hours in Beijing is 7.65 hours. The highest sunshine hours and the same amount of exposure are in May, the lowest sunshine hours. It also appears in December as the amount of irradiation.
How much solar energy in Beijing can contribute to society? The solar energy resources in Beijing are relatively rich, and belong to the second-class regions in the country. People use solar energy to make a variety of products to serve humans, including light-to-heat conversion products (such as water heaters, solar cookers, solar houses, dryers, seawater distillation units and greenhouses), photoelectric conversion products such as solar cells, and Photochemical conversion products, etc. For example, for a solar water heater, assuming an average daily efficiency of 0.50, the heat per metre of hot water sump per year (calculated by 365 days) is 2,632,380 kilojoules. If the heat is used to heat the tap water and the heating temperature difference is 30 ° C, about 20 tons of hot water per meter per year can be obtained. The seepage irrigation tank consists of three parts: seepage tank, seepage pipe and valve. The capacity of the seepage tank is above 10 m3. The water pipe is 100 cm long and the plastic pipe is 2 cm in diameter. Each hole is about 40 cm. 3 needles are made on both sides and above. Large holes, the manifold is mounted on a valve 10 cm high from the bottom of the tank, and a filter is installed on each of the seepage pipes to prevent blockage of the pipes. The overall structure is shown in the schematic. For an orchard with a line spacing of 3 meters, one percolation pipe should be buried in each row. If the row spacing is more than 4 meters, two seepage pipes should be buried. When the pipe is buried, it should be combined with the autumn base fertilizer.
8 Application of soil water retention agent It is an effective method for water conservation and conservation of dryland orchards lacking irrigation conditions. After applying the soil water retention agent, the soil moisture content can be increased by more than 9% in the first year, by more than 6% in the second year, and by more than 4% in the third year. There is a waterproof layer near the soil layer of about 45 cm to prevent moisture infiltration, where the soil moisture content is the highest. The application method is to open a groove 10 cm deep and 40 cm wide around the inner edge of the vertical projection of the fruit tree, 20 g or 30 g per plant, and apply the water retaining agent to cover the soil.