This paper calculates the thermal insulation thickness of the "steal sheated steal" directly buried steam pipe with air thermal insulation layer under the condition of different temperatures,and compares it with the system without air thermal insulation layer.

To solve this problem,the style of ditch with narrow and deep compound section and together with man_made ice_cover,air thermal preservation layer and other technical measures were taken in the design of Shunli River Hydropower Station water diversion ditch in Yichun City of Heilongjiang Province.

Variation of apple tree canopy-air temperature difference and its relations to environment factors;