In order to evaluate the vacuum of evacuated collector tube with outer wall temperature, the heat transfer balance of the receiver was taken into consideration and an expression for the relation between outer wall temperature of glass tube and heat loss of the receiver was deduced. A correlation formula of test fitting for the vacuum thermo-receiver PTR70 was used to determine the outer wall temperature range for its normal operation under different wind speed, ambient temperature, solar radiation intensity and working fluid temperature. The result shows that the change of environment changes the glass temperature alone and its influence on the heat loss of the receiver is comparatively less. The glass temperature reduces rapidly at first and then gradually tends to be in equilibrium with increasing of wind speed. When the environmental temperature rises, the glass temperature increases linearly. The glass temperature is little affected by the change of solar radiation intensity. The working fluid temperature has main influence on the heat loss of PTR70. Both the glass temperature and heat loss increase with working fluid temperature, and the increasing amplitude gets bigger and bigger.%为了利用玻璃管外壁面温度判别集热管真空,考虑集热管的传热平衡,推导出玻璃管外壁面温度与集热管热损失的关系表达式,结合PTR70真空集热管实验拟合关联式,确定不同环境风速、环境温度、太阳辐射强度以及管内循环工质温度下,PTR70真空集热管处于良好运行状态时的玻璃管外壁面温度范围.结果表明:环境变化仅改变玻璃管外壁面温度,对集热管热损失的影响相对较小.随着环境风速的增大,玻璃管外壁面温度先是急剧减小,然后趋于平缓；随着环境温度的升高,玻璃管外壁面温度呈线性升高；太阳辐射强度的变化对玻璃管外壁面温度几乎没有影响.工质温度是影响PTR70真空集热管热损失的最主要因素,玻璃管外壁面温度和集热管热损失都随工质温度的升高而增大,且增幅越来越大.
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