空气浴条件下三水醋酸钠相变材料的储热性能实验

Experimental study on the thermal energy storage characteristic of sodium acetate trihydrate as phase change material under the air bath condition

三水醋酸钠(CH_3COONa·3H_2O)作为一种无机相变储能材料,具有潜热值高、导热性能好等优点,但是其在凝固过程中过冷度大制约了CH_3COONa·3H_2O的应用。为了调节CH_3COONa·3H_2O在空气浴条件下的过冷度,本文选用Na_2HPO_4·12H_2O、Na_2CO_3·10H_2O、Na_4P_2O_7·10H_2O、Na_3PO_4·12H_2O、Na_2SiO_3·9H_2O、Na_2S_2O_3·9H_2O和Na_2B_4O_7·10H_2O这7种无机水合盐材料作为成核剂,采用步冷曲线法在高低温试验箱中进行过冷度调节实验和热循环实验。结果表明:在空气浴条件下,质量分数为96%CH_3COONa·3H_2O+2%Na_2HPO_4·12H_2O+2%羧甲基纤维素的复合相变材料过冷度最小,为5.6℃;将复合相变材料进行25、50和75次热循环后,其相变点温度几乎维持不变,过冷度随循环次数增加而逐渐增大,相变潜热值随循环次数的增加逐渐减小。本研究丰富了CH_3COONa·3H_2O相变材料的过冷度调节方案,为其工程化应用提供了参考。

Sodium acetate trihydrate（SAT）,which has high energy storage density and high thermal conductivity,is an important phase change material（PCM）for thermal storage.But it suffers from serious supercooling during the solidification process,which constrains its application.In this study,seven kinds of nucleating agents（Na2HPO4·12H2O,Na2CO3·10H2O,Na4P2O7·10H2O,Na3PO4·12H2O,Na2SiO3·9H2O,Na2S2O3·9H2O and Na2B4O7·10H2O）were proposed to reduce the degree of supercooling of SAT.With the help of the high-low temperature test chamber,the experiments were performed to investigate the degree of supercoiling,and to validate the thermal stability of composite PCM by using the curve law of step.As a result,the composite PCM with the mass fraction of 96%CH3COONa·3H2O＋2%Na2HPO4·12H2O＋2% carboxymethycellulose presents the smallest the degree of supercooling,which is 5.6℃.Moreover,the phase transformation point of the composite PCM varies a little with 25,50 and 75 thermal cycles.While its latent heat would decrease and the degree of supercooling would increase with the number of thermal cycles increasing.Therefore,this study enriches the adjustment program of the degree of supercooling of SAT,and will be evaluated for engineering application in future offerings.