Effect of external thermal insulation layer on the Chinese solar greenhouse microclimate

In order to optimize the heat preservation capacity of Chinese solar
greenhouse (CSG) and further reduce energy consumption, we clarified the
mechanism of the external thermal insulation layer that affecting the
microclimate environment of CSG. The most excellent thickness of the
external insulation layer of the solar greenhouse envelope structure in
high latitude and cold region has been indicated. A three-dimensional
mathematical model was developed based on computational fluid dynamics
(CFD) and verified using experimental measurement. The temperature
variations, heat variations and economic benefit were analyzed. The
results indicated that covering the outer surface of the enclosures with a
thermal insulation layer could effectively increase the greenhouse
temperature by 1.2~4.0°C. SW had the lowest unit cost (USD 282.52/°C), but
it limited the increase in greenhouse air temperature. Covering the outer
surface of the north wall with insulation layer has better profitability
and higher cost performance than that of the side wall and the north roof.
During the construction of the greenhouse in high latitude and cold
region, CC as the optimal solution could raise the greenhouse air
temperature maximally. The optimal thickness of the external insulation
layer of each maintenance structure is obtained as follows: north wall 80
mm, side wall 80 mm, north roof 100 mm.