Monitoring Of Internal Environmental Factors In A Double-film Solar Greenhouse In Daqing Area

Solar greenhouse is a main mode of facility production in our country at present.Solar radiation energy is absorbed in daytime time to convert heat energy to complete inner energy conversion of greenhouse and realize greenhouse production.Due to the special geographical environment,cold winter climate and insufficient illumination,the overwintering production of greenhouse can not meet the requirement of plant temperature,and it is easy to produce low temperature chilling damage.According to its own advantages and disadvantages,Daqing City has introduced a double-film solar greenhouse.By increasing the inner membrane of the greenhouse,reducing the outflow of greenhouse heat,reducing the entry of low temperature outside,and improving the performance of nighttime heat preservation in the greenhouse,Meeting the requirement of temperature for the production of plants in greenhouse in Winter.Compared with Daqing single film solar greenhouse,two greenhouses were monitored in December 2016 to March 2017,December 2017 to March 2018,and the coldest period in winter in Heilongjiang region.The internal temperature in the east-west direction and the north-south direction of the double-film solar greenhouse and the single-film solar greenhouse were monitored,and the temperature variation and temperature distribution of each monitoring point were analyzed.The soil layer temperature of double film solar greenhouse and single film solar greenhouse was monitored,and the variation of soil layer temperature in east-west direction and north-south direction was analyzed.The variation law of soil temperature at different depths and the heating rate of the same depth soil layer were demonstrated.And the influence of the east-west gable shadow on the temperature rise and cooling of the soil layer was explained,and the distribution of light intensity in the east-west direction and the north-south direction of the double-film solar greenhouse and the single-film solar greenhouse during the daytime period was monitored.This paper studies the intensity of light distribution on the front and back slope of greenhouse;monitors the temperature variation and distribution of wall in greenhouse;at the same time monitors the variation law of internal humidity in greenhouse under different weather conditions（cloudy,snowy and sunny）.1、The results showed that the average daily mean minimum temperature was increased by 27.15 in two℃-film solar greenhouse,the lowest temperature in greenhouse was 4.8 higher ℃than that in single-film solar greenhouse,and the minimum temperature in nighttime greenhouse was 3.1 ℃.The temperature difference in the east-west,north-north,east-west,east-west and north-south directions is 0-2.7 ℃,0-3.9 ℃,0-4.6 and 0℃-7.2 ℃,respectively.The temperature difference in east-west and north-south direction of double-film solar greenhouse is smaller than that in single-film solar greenhouse,and the temperature distribution in double-film solar greenhouse is uniform,which is suitable for planting.The temperature environment of greenhouse was better than that of single film solar greenhouse.2、The soil temperature of double-film solar greenhouse was higher than that of single-film solar greenhouse,and the soil temperature of double-film solar greenhouse and single-film solar greenhouse changed obviously at 10 cm ²⁰cm ^{-130 cm},the range of soil layer temperature was 0-4.5 ℃,and the lowest soil temperature of double-film solar greenhouse was 9.5 ℃.The maximum soil temperature is 15 ℃,and the temperature difference of soil layer is 0-2 at the same time between the east℃-west direction and the north-south direction.The lowest soil layer temperature is 6.5 ℃,the highest soil temperature is 13.5 ℃,and the temperature difference between east and west is 0-3.5 ℃.3、The average light intensity of double film solar greenhouse was 48.68 KLX in winter,which decreased gradually from south to north.4、 The internal humidity environment of double film solar greenhouse is better than that of single film solar greenhouse,and the internal humidity of double film solar greenhouse is always lower than that of single film solar greenhouse under different weather conditions,and the maximum humidity value of double film solar greenhouse at night is more than 80.In sunny,cloudy,snowy weather conditions,greenhouse internal humidity values: snow > cloudy > sunny.The results showed that the maximum humidity value of the monitoring point above the 10 cm film was 100,the maximum temperature value was-0.3 ℃,the maximum humidity value of the monitoring point at the 10 cm point under the two-layer film was 93.9cm,the maximum temperature value was 3.1 ℃,and the maximum temperature value was 3.1 ℃at night.the segment effectively reduces the humidity by 6.1 percent,increases the temperature value of 3.4 DEG C,and shows that the two-layer membrane can help improve the overall temperature and humidity environment inside the greenhouse and play the role of warming and reducing humidity.5、The wall of the back wall of greenhouse is absorbed by day time,heat energy is stored,heat is dissipated at night,and heat energy is converted.The wall of the rear wall of double film solar greenhouse is absorbed at the monitoring point of 80 cm 120 cm,and the heat dissipation is good,which is better than that of 40 cm / 160 cm.The average minimum wall temperature at night is 2.15 higher than that in greenhouse,which indicates that the backwall is a greenhouse ℃heat source at night,which is helpful to supplement the greenhouse heat.