太阳能直接吸收相变集-蓄热器的放热特性研究

The phase change material (PCM) -based direct absorption/storage solar collector (DASSC) has the advantages of less heat transfer process, lower thermal energy loss, and higher photothermal conversion efficiency. The PCM exhibits limited light absorption capacity and low thermal conductivity, leading to significant temperature gradients and a low heat transfer rate in DASSC. Current research predominantly addresses the heat storage process in DASSC, with insufficient focus on the characteristics of the heat release process. To address this gap, a photothermal conversion shaped composite PCM (CPCM) is prepared using a melt blending method in conjunction with a vacuum adsorption technique. The DASSC is subsequently developed, leveraging the high absorption and substantial heat storage density properties of the CPCM. The light absorption and phase change characteristics of the CPCM are tested, and the effects of inlet temperature and Reynolds number of the heat transfer fluid on the heat release characteristics of the DASSC are investigated. The sensitivity and correlation of these two parameters on the heat release rate of DASSC are analyzed using the Morris method. The findings indicate that the absorbance of CPCM is 3.03 times that of pure PCM. Additionally, when the inlet temperature decreases from 16.0℃ to 10.0℃, the average heat release rate of DASSC increases by 47.7%. As the Reynolds number increases from 2462 to 5628, the average heat release rate of the DASSC exhibits a 15.0% enhancement. The sensitivity and correlation of the inlet temperature on the heat release rate of the DASSC are significantly higher than those of the Reynolds number. The optimal value of the inlet temperature should be calculated separately in the design and optimization of the heat release performance of DASSC, while the Reynolds number can be directly determined based on the positive and negative correlation.