累计太阳辐照量对真空管太阳能热水器日得热量的影响

The Influence of Daily Radiation Collected on the Daily Heat Gain of an Evacuated Tube Solar Water Heater

累计太阳辐照量17MJ/m2对应的日有用得热量Q17是评价太阳能热水系统热性能好坏的重要参数之一.在累计太阳辐照量达到测试要求以及其他测试条件相似的条件下,利用试验测试研究了累计太阳辐照量对真空管太阳能热水器系统日有用得热量Q17的影响.结果表明:日得热量随累计辐照量的增加而呈线性增加的关系,而系统的能效系数和日有用得热量Q17基本不受累计辐照量的影响;当测试条件由累计辐照量不小于17MJ/m2减小至累计辐照量不小于16 MJ/m2时,系统的日有用得热量Q17和能效系数没有明显的降低,说明新国标中对测试累计辐照量的修改是合理的.

Q17,daily solar heat gain corresponding to 17 MJ/m2 of daily collectible radiation is one of key parameters to evaluate the thermal performance of a solar water heater.In this paper,the influence of daily collectible radiation on the daily heat gain of an evacuated tube solar water heater is studied experimentally in the radiation condition described in GB/T 18708.Results showed that the daily heat gain linearly increases with the increase of daily collectible radiation,but Q17 and system＇s efficiency coefficient almost kept constant.It was also found that when the testing condition with the daily collectible radiations being not less than 17 MJ/m2 changed into that of not less than 16 MJ/m2,change of Q17 and the system＇s energy efficiency coefficient was not insignificant,implying that the testing conditions about daily collectible radiation specified in the revised version of GB/T19141 was reasonable.