高潜热相变砂浆与相变板墙体性能对比研究

相变储能墙体面临着相变温度不适宜、储能能力低、构建形式多但缺乏性能对比分析等问题,为此,本文以相变砂浆、相变板墙体为对象,对其性能进行优化和对比研究。采用固、液石蜡、HDPE按比例熔融混合制备出相变温度约为34℃的定形相变材料,该材料无泄漏、形状稳定,潜热为现有文献的2倍多。基于该材料制备出相变砂浆、相变板材,并构建两类相变-混凝土墙体结构,研究在相同边界条件和初始条件下两者的传热特性及节能效果。结果表明,以普通砂浆墙体为对照,相变砂浆、定形相变板可将内壁面最高温降低0.73℃、1.76℃,定形相变板保温隔热性能最优。定形相变板可将空调热负荷降低21.9%,高于相变砂浆;但其原料成本为普通砂浆的3.38倍;成本增幅较相变砂浆高出32.8%,而成本回收周期低33.3%。     

Axial Magnetic Field Effects on Xenon Short-Arc Lamps

The effect of an axial magnetic field （AMF） on an old xenon short-arc lamp is experimentally investigated in this work. As the AMF increases up to 18 roT, the visible radiation power and electric power ascend more than 80% and 70% respectively, and the radiation efficiency is improved by 23% for the best increment at 12 mT AMF. The measurement of radiation intensity shows that the increment of radiation intensity comes mostly from the plasma area close to the cathode tip, and partially from the other area of the arc column. Successive images of the arc indicate that the arc column not only rotates about its axis, but revolves around the axis of electrodes with the AMF. The arc column structure is constricted, distorted and elongated as the AMF increases. It is suggested that the improvements of the radiation intensity and radiation efficiency are attributed to the constriction of the arc column, which is mainly induced by the enhanced cathode jet.     

磁旋转电弧中热阴极弧根形态的实验研究

阴极弧根形态对电弧状态和电极损耗有着重要影响。在同轴电极磁旋转电弧等离子体发生器中,利用高速CCD观察了阴极弧根斑点形态随外加轴向磁场的演化过程,采用双波长法从CCD影像得到阴极端面温度分布;利用水冷电探针对近阴极区等离子体参数进行诊断,得到了阴极附近电子温度及阴极区位降。实验结果表明:(1)在50 A电弧电流下,随着轴向磁场从0.01 T增加到0.02 T,阴极端面最高温度下降,阴极弧根斑点增大,阴极附近等离子体电子温度逐渐降低,阴极弧根为收缩模式;(2)在100 A电弧弧电流下,轴向磁场从0.01 T增加至0.015T,阴极状态变化趋势与前相同;(3)在100 A电弧弧电流下,当轴向磁场增大到0.02 T时,弧根斑点弥散均匀,阴极区位降明显升高,阴极弧根模式由收缩模式转变为扩散模式。分析认为,磁旋转电弧中弧根模式的转变是一个突变的过程。