中文摘要：

蒸汽热力管道设置空气层和将空气层抽真空是提高蒸汽热力管网输送效率的有效方法。提出了空气层内由导热、对流和辐射传热组成的复合传热计算方法。结合实验，分析了复合传热计算方法的可行性及在不同空气层绝对压力（1000～101325Pa）、不同蒸汽温度（200、250、300℃）下空气层传热量的变化规律。计算值与实验值的相对误差低于8．6％，证明计算方法可行。随空气层绝对压力的下降空气层传热量下降，当空气层绝对压力降至2kPa时，空气层已获得较满意的保温性能。

英文摘要：

The installation of air layer in steam heating pipeline and the creation of vacuum in air layer are an effective method to improve the transmission efficiency of steam heating network. The calculation method of compound heat transfer composed of heat conduction, convection and radiation heat transfer in the air layer is put forward. The feasibility of the calculation method of compound heat transfer and the variation rule of heat transfer in the air layer under different absolute pressure of 1 000 - 101 325 Pa and different steam temperature of 200 ℃, 250 ℃ and 300 ℃ are analyzed with experiment. The relative error of below 8.6% between calculated value and experimental value demonstrates that the calculation method is feasible. The heat transfer in the air layer decreases with decreasing of absolute pressure in the air layer. The air layer has a satisfactory thermal insulation performance when the absolute pressure in the air layer is decreased to 2 kPa.