本文运用直接模拟蒙特卡洛方法(Direct Simulation of Monte Carlo,DSMC)采用结构化网格对槽式太阳能集热器真空夹层内的流动与换热进行了数值模拟。模拟结果表明:在壁面温差一定条件下,环形空间内压力越大,热损失越大。而在0.1～10 Pa压力区间内,随着环形空间内的压力升高,热损失呈接近线性增加。而当环形空间内的压力低于0.1Pa时,热损失随压力的降低基本不变。因此没有必要将集热器的真空度抽到0.1 Pa以下。 In this paper, we use the Direct Simulation of Monte Carlo (DSMC) to simulate the flow and heat transfer in the vacuum interlayer of a slotted solar collector using a structured grid. The simulation results show that under certain conditions of wall temperature difference, the larger the pressure in the annular space, the greater the heat loss. In the pressure range of 0.1-10 Pa, the heat loss shows a nearly linear increase with the increase of the pressure in the annular space. When the pressure in the annular space is less than 0.1 Pa, the heat loss decreases substantially with pressure. Therefore, it is not necessary to draw the collector vacuum below 0.1 Pa.