Abstract
Although green house air heaters are often used throughout the southern Yangtze River basin in China, few data exist to
indicate the proper placement of warm-air-delivery ducts, the arrangement of their air outlets, and the impact of thermal
screens on the heated green houses environment. To better understand these issues, we develop herein a thermal-environment
model of a Venlo-type glass green house on a winter night. The model is based on the standard k turbulence model, the
buoyancy model, and the porous-medium model, and simulations based on this model are done by using commercial
computational fluid dynamics software. The results indicate that the thermal distribution at the crop-canopy height
significantly impacts crop growth and quality, so we used temperature distribution to evaluate the effect of the various
heating parameters. We find that a higher average temperature and a greater temperature difference occur for downward
vents than for horizontal vents. In addition, higher average temperature and smaller temperature difference occur for a
thermal screen 3.6 m above the floor than for no thermal screen. Finally, we optimize the placement of the warm-air-delivery
duct and the location of the outlet openings to obtain a more uniform thermal distribution and, thereby, better crop growth.
