| In recent years, the development of solar greenhouse in Henan is rapid, but its type is various, there is no uniform standard for structure form and problems in development process are also increasingly prominent, such as low degree of environmentally controlled, poor ability of preventing natural disasters and so on. In case of solar greenhouse structure diversification, not only there must be the theoretical research, but also to strengthen the comparison of physical measurement analysis, so as to evaluate scientifically on the advantages and disadvantages of sunlight greenhouse structure. This paper compared the structure of three types of solar greenhouses in Henan, researched the changes of temperature and total solar radiation in different solar greenhouses under different weather conditions, screened out the suitable solar greenhouse that can be used in winter in Henan and researched its change rules of indoor environment. Thus, we could provide theoretical basis to standardize greenhouse production, speed up the industrial structure adjustment and improve greenhouse production benefit in Henan province. Specific research results were as follows:1. Comparative study of the three types of solar greenhousesIn aspect of structure, the front roof angle, back roof angle, span, length, ratio of front roof horizontal projection and net span, entire thermal resistance and heat inertia index of back wall of ZG-1solar greenhouse (No.3) were superior to those of general solar greenhouse with8m span (No.1) and sinking solar greenhouse with cob wall (No.2).No matter what the weather is, the daily variation trend of air temperature and temperature of inner surface of back wall in three solar greenhouses were down first, then rising, fall again, but the maximum temperature and the change range of temperature on sunny day was maximum, on cloudy day was second, on snow day was minimum. Mean air temperature, temperature difference inside and outside greenhouse, mean temperature difference between temperature of inner surface of back wall and air temperature and difference between day temperature and night temperature (DIF) in three greenhouses were No.3>No.2>No.1. DIF on sunny day was maximum, on cloudy day was second, on snow day was minimum.Air temperature inside and outside three solar greenhouses were significant positive correlativity, linear regression equation, exponential equation and binomial curve equation can be used to fit the correlativity on sunny day, cloudy day and snow day, respectively. The air temperature time-varying in three solar greenhouses presented parabolic trend, but there were slightly difference on their shapes due to weather conditions and greenhouse structure.Total solar radiation transmittance on sunny day was greater than that on cloudy day, total solar radiation transmittance and degree of radiation uniformity in three greenhouses under the same weather condition and at the same time were No.3>No.2>No.1. Diurnal variation of total solar radiation transmittance and degree of radiation uniformity were consistent with solar altitude, which increased gradually in the morning,13:00achieved maximum, then decreased gradually.In terms of structure, air tempereture and total solar radiation in greenhouse, peformence of lighting and insulation in ZG-1solar greenhouse was best.2. Environmental characteristics in ZG-1solar greenhouseTemperature at night on the day before overcast for several days in greenhouse dropped rapidly, during overcast for several days the temperature rised slightly at daytime and dropped slowly at night. Mean air temperature in greenhouse during overcast for several days were low and less than9℃, indoor and outdoor temperature difference was small, which was not conducive to crop growth and development. There was extremely significant positive correlation between minimum air temperature indoor and outdoor, which could be described by binomial curvilinear regression equation namely y=0.0214x2+0.6017x+9.8706(-15≤x≤5).On east-west direction, on sunny day air temperature in the cast was slightly lower than that in the west, in the middle was the highest in the morning, air temperature distribution was uniform at noon, air temperature in the east was slightly higher than that in the west.in the middle was the highest in the afternoon. On cloudy day air temperature in greenhouse was similar in both east and west and temperature distribution is uniform. On south-north direction. on sunny day air temperature decreased gradually from north to south on upper layer (apart from ground2.0m), were similar on middle level (apart from ground1.0m). increased gradually from north to south on sublayer (apart from ground0.5m) at daytime. Air temperature decreased gradually from north to south on middle and lower layer, temperature near the back wall is lower, gradually decreased from the middle to the south at night. On cloudy day temperature increased from north to south at daytime, its distribution at night was consistent with that on sunny day. On vertical direction, on sunny day air temperature increased with the increase of height at daytime, decreased with the increase of height in the south (apart from back wall more than4m) at night. On cloudy day air temperature increased with the increase of height at daytime, but increased little in the north (apart from back wall2m), its distribution at night was consistent with that on sunny day. Temperature of inner surface of back wall increased with the increase of height at daytime and changed not obvious at night on sunny day, on middle level was highest and on upper layer was lowest on cloudy day.The change of total solar radiation indoor was consistant with that outdoor,12:00-13:00achieved the maximum. Daily variation of total solar radiation indoor presented parabolic trend, we can use y=-20.45x2+181.97x-113.63(on sunny day) and y=-3.3387x+28.849x-1.1786(on cloudy day) to predict total solar radiation during9:00-16:00in solar greenhouse. Total solar radiation indoor and outdoor had significant positive correlation which was y=0.437x1.0141On east-west direction, on sunny day distribution of total solar radiation is homogeneous at noon, total solar radiation near the east-west gable is weak due to the effect of shade of east-west gable in the morning and afternoon. On coludy day, total solar radiation weakened gradually from west to east in the morning, not varied much from west to east at noon and afternoon, on the whole, its distribution is homogeneous in a day. On south-north direction, on sunny day total solar radiation enhanced gradually from north to south in the morning and afternoon, enhanced and then weakened from north to south at noon. On cloudy day, it enhanced gradually from north to south, just the increasing range at different time were slightly different.With the increase of total solar radiation, temperature in greenhouse was higher, and vice versa, and there was a significant positive correlation between them, which could be matched by linear regression equation y=0.0502x+8.8362. |
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