【摘要】：在去離子水中加入Cu納米顆粒,通過(guò)添加分散劑和超聲波振蕩,配制均勻分散的Cu-H_2O納米流體。在100 Pa初始?jí)毫ο?通過(guò)改變納米顆粒粒徑、納米流體質(zhì)量分?jǐn)?shù)研究均勻分散的納米流體對(duì)真空閃蒸制冰實(shí)驗(yàn)特性的影響。結(jié)果表明,水中加入納米顆粒(無(wú)分散劑,納米顆粒有沉降現(xiàn)象),可降低水過(guò)冷度,縮短相變結(jié)冰時(shí)間,而分散均勻無(wú)沉降的納米流體可顯著縮短相變時(shí)間,使過(guò)冷度降低37%;在閃蒸瞬間,納米流體對(duì)液相降溫過(guò)程幾乎沒(méi)有影響;納米流體質(zhì)量分?jǐn)?shù)越大,結(jié)冰時(shí)間越短,固相降溫段降溫速率越大;隨著納米顆粒粒徑減小,相變時(shí)間縮短,而固相降溫階段溫降速率幾乎相同,較低濃度時(shí)(0.05%),粒徑的改變,對(duì)納米流體過(guò)冷度影響不大,基本維持在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，

本文編號(hào)：2447637