Analysis of temperature and humidity in a large-scale asymmetric plastic-covered greenhouse with a water-controlled brewed hot system
In order to address low land-use efficiency, an unfriendly mechanization environment, and other problems in Chinese solar greenhouses, a new, large-scale asymmetric plastic-covered tunnel with a water-controlled brewed hot system (an experimental greenhouse, GH-F) was designed. GH-F is oriented in the east-west direction and has a double roof with a wide steel frame. The sun projection on the south and north roof is 10-12 and 7-8 m, respectively. It also has a 1×0.5 m2 fermentation groove in the north roof. The experiment was conducted from 15 December 2015 and 5 February 2016. We compared the results between a traditional brick-structure greenhouse (GH-D) and GH-F for temperature exchange, humidity exchange, and building expenses. Our results showed that GH-F had both thermal insulation and economic benefits. The highest temperature difference between GH-F and the environment was 21.9°C during winter. The average night air temperature in GH-F was kept above 8°C, which was only 1°C lower than that in GH-D. This difference was consistent during cloudy and non-cloudy nights. Temperatures in the GH-F system were higher than the environmental temperature, ranging from 11.1 to 15.3°C during non-cloudy nights, 8.5-11.7°C during cloudy nights, and 12.3-13.7°C during snowy nights. However, the system temperature difference between GH-F and GH-D during snowy nights was dependent on time. The relative humidity in GH-F was 2-7% lower than that in GH-D at night. The initial cost for GH-F was 200 yuan m-2, which was 20.3% lower than the cost of GH-D. In summary, GH-F can improve land-use efficiency, increase thermal insulation, and decrease initial building costs and relative system humidity. Thus, GH-F is an appropriate design for vegetable production in northwestern and mid-eastern areas of China, especially in areas that are primarily sunny during winter.
Hu, X., Song, X., Xiao, J., Guo, Y. and Li, J. (2018). Analysis of temperature and humidity in a large-scale asymmetric plastic-covered greenhouse with a water-controlled brewed hot system. Acta Hortic. 1227, 173-180
GH-F, temperature, relative humidity, building cost