我国北方冬季夜间的最低温度可达零下10—40℃。在这样低的气温下,平板集热器中的存水会很快地结冰,导致吸热板胀裂。因此,入冬后不得不将水排空,停止使用。全国约有八万平方米的太阳热水器就是这样过冬的。不但利用率低(一年中约有一半时间闲置),而且由于水排空后集热器和水箱的内表面接触空气,加速了材料(一般为钢材)的腐蚀,缩短了 The lowest temperature in northern China in winter night up to minus 10-40 ℃. At such low temperatures, the water in the flat-plate heat collector will quickly freeze, causing the heat-absorbing panel to burst. Therefore, the winter had to empty the water, stop using. About 80,000 square meters of solar water heaters throughout the country are so winter. Not only is the utilization rate low (about half of idle time in a year), but also the corrosion of the material (usually steel) is accelerated due to air contact with the inner surface of the collector and tank after the water is drained