光电-光热联合木材太阳能预干燥设备性能探析

Performance study on wood solar dryer combined with solar photovoltaic-thermal generator

设计了一种集太阳能光伏发电装置、温室型太阳能干燥室及控制系统为一体的光电-光热联合木材太阳能干燥设备,探讨了该设备的光电、光热性质及3种试材在设备中的自然对流和强制对流干燥特性。研究结果表明：该设备2015年8月的总发电量可达221.37 k W·h,满足负载的能耗需求,并节余电量39.9 k W·h;在晴天和晴转多云两种天气条件下,干燥室内空载平均温度分别为51.2和48.6℃,负载平均温度分别为46.7和42.7℃,日累计辐射量分别为20.7和14.3 MJ/m2,日光伏发电量分别为9.44和5.99 k W·h;采用自然对流和强制对流两种通风方式,后者温度分布更均匀,但干燥室内整体温度出现一定幅度下降;相比于自然干燥,自然对流和强制对流两种方式可分别提高干燥速率41.4%~116.3%,且两种方式对改善木材含水率分布的均匀性、降低木材干燥应力的效果显著。

A wood solar dryer combined with solar photovoltaic-thermal generator,consisting of solar energy photovoltaic power generation device,greenhouse type solar dryer and control system was designed and manufactured. It can complete the drying process without external power supply. The photovoltaic and photothermal properties of the device were examined using solar radiation meters and temperature sensors. Drying performance for the 3 types of wood samples were studied through detecting the layered moisture contents and drying stress index when the samples were solar-dried in the natural convection and forced convection. The results showed that the gross generating power capacity in August 2015 was 221. 37 k W·h. It could not only meet the drying requirements but also save 39. 9 k W·h energy. When the device was under sunny and cloudy days,the average temperatures of the no-wood-load dryer was 51. 2 and 48. 6 ℃,respectively,while the average temperatures of the full-load dryer was 46. 7 and 42. 7 ℃,the daily total radiation was 20. 7and 14. 3 MJ / m2,the photovoltaic power generation capacity was 9. 44 and 5. 99 k W·h,respectively. Compared with the natural convection drying,the temperature distribution in the forced convection drying condition was more uniform,but the entire temperature of the drying chamber was decreased. When drying the 3 types of wood,the natural convection can increase the drying rate by 41. 4%,55. 0% and 43. 7%,and the forced convection can increase the drying rate by 81. 0%,116. 3% and 98. 9%,respectively,compared with the natural air-drying. The solar drying remarkably improved the uniformity of the wood moisture content distribution and reduced wood drying stress. The deviations of the average moisture contents for the two kinds of air convection patterns were reduced by 0. 99% and 0. 86%,and drying stress index were reduced by 0. 43% and 0. 41%,respectively.