Observations made during experimentation on SAH with encapsulated PCM on its absorber plate

A double pass packed bed solar air heater attached with encapsules filled with paraffin wax on its absorber plate is experimentally tested. Encapsules in circular and square cross sections in staggered and inline grid arrangements are used. Mass flow rate of air is changed to 0.00879 to 0.01484 kg/s. The absorber plate with cylindrical capsules in staggered arrangement was attached to SAH on the first day of the experiment and the blower was operated to supply air at a mass flow rate of 0.01484 kg/s. The direct solar radiation was recorded by placing solar power meter (WACO TM-206) perpendicular to the upper glass of the experimental setup. Thermocouples placed at different locations of SAH were connected to a multi-point temperature indicator to manually record temperatures at respective locations. The blower was allowed to run continuously for 30 minutes for each reading to ensure steady-state conditions are attained. Observations were recorded at every 5 minutes within these 30 minutes of time interval. PCM inside the capsules are charged during daytime from 9.45 a.m. to 2.15 p.m. The temperature of the air at SAH inlet and exit, temperatures of packed bed, absorber plate, lower glass, upper glass and PCM in capsules were manually recorded. In between 2.20 p.m. to 4.20 p.m, blower was switched off and the experimental setup was completely placed under insulation covers to minimize the heat loss to the surroundings. After 4.20 p.m. insulation covers were removed and blower was switched on to supply the air. This time PCM discharges stored heat to the air flowing over the capsules. The experiment for discharging process was conducted between 4.20 p.m. to 5.40 p.m. The temperature of the air at SAH inlet and exit, temperatures of packed bed, absorber plate, lower glass, upper glass and PCM in capsules were once again manually recorded.本研究对一种在吸热板上安装填充石蜡封装容器的双通道填充床太阳能空气加热器（double pass packed bed solar air heater）开展了实验测试。实验采用了横截面为圆形与方形的封装容器，排布方式包含错列与顺列网格布局。空气的质量流量设置为0.00879至0.01484 kg/s。实验首日，将搭载错列排布圆柱形封装容器的吸热板安装至太阳能空气加热器（solar air heater, SAH），并启动鼓风机以0.01484 kg/s的质量流量输送空气。通过将太阳能功率计（WACO TM-206）垂直安装于实验装置的上玻璃盖板处，以记录直接太阳辐射量。布置于SAH不同位置的热电偶连接至多通道温度显示器，用于手动记录各对应位置的温度。每次读数前，鼓风机需连续运行30分钟以确保达到稳态工况。在该30分钟的时间间隔内，每5分钟记录一组观测数据。封装容器内的相变材料（Phase Change Material, PCM）于上午9:45至下午2:15完成蓄热过程。手动记录太阳能空气加热器进、出口空气温度，填充床、吸热板、下玻璃盖板、上玻璃盖板以及封装容器内PCM的温度。在下午2:20至下午4:20期间，关闭鼓风机，并将实验装置完全覆盖隔热罩以减少向环境的热损失。下午4:20后移除隔热罩并启动鼓风机输送空气，此时封装容器内的PCM将储存的热量释放给流经其表面的空气。放热过程的实验时段为下午4:20至下午5:40，再次手动记录太阳能空气加热器进、出口空气温度，填充床、吸热板、下玻璃盖板、上玻璃盖板以及封装容器内PCM的温度。