Al-Si合金/高钙粉煤灰基高温相变蓄热球的制备及应用性能

Preparation and application performance of Al-Si alloy/high calcium fly ash based high temperature phase change heat storage spheres

以高钙粉煤灰为基体材料,Al-Si共晶合金粉为相变介质,利用干压成型及混合烧结法制备了直径为15 mm蓄热球,研究了成型压力及合金粉含量对蓄热球综合性能的影响,并对其堆积承载高度及性价比进行了估算和分析。结果表明:相同成型压力下,合金粉含量越高,蓄热球的相变潜热、密度及开裂载荷越高。合金粉含量相同时,蓄热球密度及开裂载荷随成型压力的增大而增大,而相变潜热基本不受成型压力影响。蓄热球相变潜热越高其熔化功率越大,说明其相对导热性能越好,而密度对熔化功率影响不大。以单个蓄热球常温下开裂载荷的大小作为堆积体底层接触力的理论峰值,估算出对应的最大理论堆积高度范围为47.7~287.2 m,而蓄热球在高温下的堆积高度均不小于20 m。利用层次分析法(AHP)对蓄热球进行综合性价比分析,当合金粉含量为40%,成型压力为8 MPa时,蓄热球综合应用性价比较优。

Using high calcium fly ash as the matrix material and Al-Si eutectic alloy powder as the phase change medium, the heat storage spheres with diameter of 15 mm were prepared by dry press molding and mixed sintering method. The influences of molding pressure and alloy powder content on comprehensive properties of the heat storage spheres were studied, and its accumulation bearing height and cost performance were estimated and analyzed. The results show that under the same molding pressure, the higher the content of alloy powder, the higher the latent heat of phase change, density and cracking load of the heat storage spheres. When the content of alloy powder is the same, the density and cracking load of the heat storage spheres increase with the increase of molding pressure, while the latent heat of phase change is basically not affected by molding pressure. The higher the latent heat of phase change of heat storage spheres, the greater the melting power, indicating that the relative thermal conductivity is better, and the density has little effect on the melting power. Taking the cracking load of a single heat storage sphere at room temperature as the theoretical peak value of the contact force at the bottom of the accumulation body, it is estimated that the corresponding maximum theoretical accumulation height range is 47.7-287.2 m, while the accumulation height of the heat storage spheres at high temperature is not less than 20 m. Analytic hierarchy process(AHP) is used to analyze the comprehensive cost performance of heat storage spheres, and when the content of alloy powder is 40% and the molding pressure is 8 MPa, the comprehensive application cost performance of the heat storage spheres is better.