| A new type of solar greenhouse called active lighting and heating storage type solar greenhouse was studied based on experimental comparison and its properties were investigated. Both tilting roof technologies and active heating storage fan systems technologies have been integrated in the new solar greenhouse so that varying incidence angle of the solar greenhouse to increase the light transmittance and to increase the efficiency of thermal storage of the back wall by manual were realized. The experiment was carried out at the modern agriculture demonstrate area located at County Zi Chang, Shaanxi during the winter of 2013. Technical performance of indoor lighting, temperature and humidity was discussed and compared theoretically. The mechanism of active lighting and heating was carried out in this study as well. The results showed that:(1) Under different weather conditions in the winter of this study, the active lighting and heating storage type solar greenhouse with the technology of tilting roof showed a better lighting performance than the common solar greenhouse. In the winter solstice day, the cloudy day and the sunny day, the average light transmittance of the active lighting and heating storage type solar greenhouse was 61.17%,58.26% and 70.81%, respectively, which increased by 7.87%,5.88% and 11.45% compared to the common solar greenhouse, respectively. Accordingly, the average indoor intensity of illumination of the active lighting and heating storage type solar greenhouse had increased by 15.42%, 11.73% and 21.28%, respectively.(2) Under experimental condition in the winter of this study, the indoor air temperature and earth temperature in the active lighting and heating storage type solar greenhouse were better than that in the common solar greenhouse. The average indoor air temperature had increased by 2.6℃, 2.1℃ and 5.3℃ in the winter solstice day, the cloudy day and sunny day, respectively. And the temperature difference value between the indoor air temperature of the active lighting and heating storage type solar greenhouse and the outdoor air temperature was above 20℃. The average indoor earth temperature had increased by 2.3℃, 3.5℃ and 2.3℃ in the winter solstice day, the cloudy day and the sunny day, respectively. And the temperature difference value between the indoor earth temperature of the active lighting and heating storage type solar greenhouse and the outdoor earth temperature was more than 15℃. In the continuous adverse weather conditions of snow, the minimum indoor air temperature of the active lighting and heating storage type solar greenhouse was still above 7.5 ℃ while the minimum indoor air temperature of the common solar greenhouse had already reached 4.2℃.(3) Under different weather conditions in the winter of this study, the indoor humidity of the active lighting and heating storage type solar greenhouse was 30.8% and 31.2%, and the indoor humidity of the common solar greenhouse was 31.3% and 32.3%. So, the indoor environment of humidity in the active lighting and heating storage type solar greenhouse was better than that in the common solar greenhouse.(4) By the view of energy source, on account of the active lighting systems in the active lighting and heating storage type solar greenhouse, the lighting roof could be adjusted to the sunlight on the basis of geographic latitude, season, date and time. So the entire lighting roof could be maintained an optimal angle to obtain a maximum indoor lighting rate, which was much better than that of the common solar greenhouse which only had a small portion of the lighting roof to receive the sunlight in the daytime. Moreover, the active lighting and heating storage type solar greenhouse could extend the effective lighting time to more than 6 hours, while the effective lighting time of the common solar greenhouse is only 4 hours.(5) By the view of energy storage of the wall in the greenhouse in the daytime, the active lighting and heating storage type solar greenhouse has not only the process relying on the passive heat storage of the inner surface of the back wall on account of heat conduction, which was the same as the common solar greenhouse, but it could also accumulate the redundant energy in the greenhouse actively into the main thermal storage layer in the back wall by making use of the active heat storage fan system artificially. And we had calculated the energy storage efficiency of our experimental greenhouses, it showed that the energy storage efficiency could be increased by 32.33% in the active lighting and heating storage type solar greenhouse compared to the common solar greenhouse. |
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