Cu纳米流体真空闪蒸制冰的实验特性
发布时间：2019-03-26 14:27
【摘要】：在去离子水中加入Cu纳米颗粒,通过添加分散剂和超声波振荡,配制均匀分散的Cu-H_2O纳米流体。在100 Pa初始压力下,通过改变纳米颗粒粒径、纳米流体质量分数研究均匀分散的纳米流体对真空闪蒸制冰实验特性的影响。结果表明,水中加入纳米颗粒(无分散剂,纳米颗粒有沉降现象),可降低水过冷度,缩短相变结冰时间,而分散均匀无沉降的纳米流体可显著缩短相变时间,使过冷度降低37%;在闪蒸瞬间,纳米流体对液相降温过程几乎没有影响;纳米流体质量分数越大,结冰时间越短,固相降温段降温速率越大;随着纳米颗粒粒径减小,相变时间缩短,而固相降温阶段温降速率几乎相同,较低浓度时(0.05%),粒径的改变,对纳米流体过冷度影响不大,基本维持在1.5℃。
[Abstract]:Cu nanoparticles were added to deionized water, and uniformly dispersed Cu-H_2O nano-fluids were prepared by adding dispersant and ultrasonic oscillation. Under the initial pressure of 100 Pa, the effects of uniformly dispersed nano-fluids on the experimental properties of vacuum flash ice-making were studied by changing the particle size and the mass fraction of nano-fluids. The results show that the addition of nano-particles (no dispersant and sedimentation phenomenon) can reduce the undercooling degree of water, shorten the freezing time of phase transition, and shorten the phase transition time of dispersed homogeneous and non-settling nano-fluids. The undercooling degree was reduced by 37%; At the flash moment, nano-fluid has little effect on the cooling process of liquid phase, and the larger the mass fraction of nano-fluid is, the shorter the ice-forming time is, and the greater the cooling rate of solid-phase cooling section is. With the decrease of the particle size and the shortening of the phase transition time, the temperature drop rate is almost the same in the solid-phase cooling stage. At low concentration (0.05%), the change of the particle size has little effect on the supercooling degree of the nano-fluid, and it is basically maintained at 1.5 鈩，
本文编号：2447637
[Abstract]:Cu nanoparticles were added to deionized water, and uniformly dispersed Cu-H_2O nano-fluids were prepared by adding dispersant and ultrasonic oscillation. Under the initial pressure of 100 Pa, the effects of uniformly dispersed nano-fluids on the experimental properties of vacuum flash ice-making were studied by changing the particle size and the mass fraction of nano-fluids. The results show that the addition of nano-particles (no dispersant and sedimentation phenomenon) can reduce the undercooling degree of water, shorten the freezing time of phase transition, and shorten the phase transition time of dispersed homogeneous and non-settling nano-fluids. The undercooling degree was reduced by 37%; At the flash moment, nano-fluid has little effect on the cooling process of liquid phase, and the larger the mass fraction of nano-fluid is, the shorter the ice-forming time is, and the greater the cooling rate of solid-phase cooling section is. With the decrease of the particle size and the shortening of the phase transition time, the temperature drop rate is almost the same in the solid-phase cooling stage. At low concentration (0.05%), the change of the particle size has little effect on the supercooling degree of the nano-fluid, and it is basically maintained at 1.5 鈩，
本文编号：2447637
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