夏热冬暖地区阳台壁挂式平板型太阳能热水器水量配比优化

基于中国夏热冬暖地区13城市的典型气象数据,利用所建数学模型对阳台壁挂式平板型太阳能热水器的水量配比、方位角因子和太阳能保证率进行了计算。结果显示,南向阳台壁挂式太阳能热水器春、夏、秋、冬4季和全年水量配比分别位于21.1~50.3、22.9~55.7、33.8~57.9、25.0~54.6和28.3~49.3 kg/m~2之间。为便于应用,该文分别给出了南向阳台壁挂式太阳能热水器水量配比与水平面日均总太阳辐射量、温升-辐射量比值、倾角间的线性关系式。对于非南向阳台壁挂式太阳能热水器,季均和年均方位角因子随方位角的增大而逐渐减小。倾角为60°~90°、方位角为10°~90°时,季均和年均方位角因子分别位于0.67~0.99和0.74~0.99之间。当方位角小于20°、30°、40°、50°时,方位角对水量配比的影响分别约为3%、7%、10%和15%。方位角位于60°~90°时,方位角对水量配比存在20%~33%左右的影响。进一步分析发现,夏热冬暖地区南向阳台壁挂式太阳能热水器的年均太阳能保证率位于0.41~0.56之间,推广应用潜力较大。

Optimization of tank-volume-to-collector-area ratio for balcony wall-mounted flat-plate solar water heater in hot summer and warm winter region of China

The thermal performance and economical efficiency of the flat-plate type solar water heater has been studied by researchers at home and abroad.In order to ensure the efficient operation of the solar water heater and user's demand to the terminal temperature of tank,the countries all over the world with different climates have given different recommended value for tank-volume-to-collector-area ratio (the ratio was abbreviated as Vt/Ac) of the flat-plate solar water heater.However,the value range of recommended value from literatures was too big for the practical application due to the complex climates.In addition,the main residential buildings in large and medium-sized cities in China were mostly high-rise buildings.The solar water heater installed on roof could only meet hot water use for the top six to eight floors.The application of the balcony wall-mounted solar water heater was the one of the effective ways to solve hot water needs for the rest of users in high-rise buildings.Based on the typical meteorological data of 13 cities in hot summer and warm winter region of China,the values of Vt/Ac,azimuth factor and solar reliability fraction of the balcony wall-mounted flat-plate solar water heater have been calculated by using the established mathematical model.The water tank terminal temperature of 60 ℃,the collector angle of 60°-90° and the azimuth angle of 0-90° were used in theoretical calculation.The results showed that,for south-facing balcony wall-mounted solar water heater in hot summer and warm winter region,the ranges of (Vt/Ac)n in spring,summer,autumn,winter and the whole year were 21.1-50.3,22.9-55.7,33.8-57.9,25.0-54.6 and 28.3-49.3 kg/m2,respectively.For convenience of the practical application,the linear regression relations between the annual average (Vt/Ac)n and the tilt angle,daily total solar radiation on the horizontal and the ratio of temperature to daily total solar radiation were given for south-facing balcony wall-mounted solar water heater.For the non-south-facing balcony wall-mounted solar water heater,the seasonal and annual average azimuth factors decreased with the increase of the azimuth angle.The seasonal and annual average azimuth factors ranged from 0.67 to 0.99 and 0.74 to 0.99 when the tilt angle and azimuth angle were respectively at 60°-90° and 10°-90°.The azimuth angle had about 3％,7％,10％ and 15％ effect on Vt/Ac for winter and spring,summer,autumn and the whole year when the azimuth angles were less than or equal to 20°,30°,40° and 50°.The azimuth angle had about 20％-33％ effect on the above-mentioned V/Ac when the azimuth angle increased form 60° to 90°.Further discussion found that the annual average solar fraction ranged from 0.41 to 0.56 for the south-facing balcony wall-mounted flat-plate solar water heater used in hot summer and warm winter region of China.