Droplet-based high heat flux dissipation technique under multi-gravitational environments has gained increasing research attention due to the increased requirements of heat dissipation in advanced air-/space-borne ele...Droplet-based high heat flux dissipation technique under multi-gravitational environments has gained increasing research attention due to the increased requirements of heat dissipation in advanced air-/space-borne electronics.In this paper,a threedimensional model was developed to investigate the impact of continuous droplets on liquid film under various Weber numbers and gravity loads.In other words,the effects of Weber number and gravity load on the flow and heat transfer characteristics were investigated.The results demonstrated that the dissipated heat flux was positively correlated with both Weber number and gravity load.A large Weber number indicated larger kinetic energy of a droplet,leading to a greater disturbance on the impacted film area.When the Weber number was doubled,the average wall heat flux could be enhanced by 36.3%.In addition,the heat flux could be boosted by 5.4%when the gravity load ranged from 0 to 1g.Moreover,a weightless condition suppressed the vapor escape rates on the heating wall where the volume fraction of the vapor on the wall could increase by 20%under 0g,leading to deteriorated heat transfer performance.The novelty in this paper lies in the accurate three-dimensional modeling of an aerospaceoriented droplet impacting two-phase heat transfer and fluid dynamics,associating macro-scale thermal performance to microscale thermophysics mechanisms.The findings of this study could guide the development of aerospace-borne spray cooling facilities for advanced aerospace thermal management.展开更多
This review focuses on recent developments in the fabrication of multiple emulsions in micro-scale systems such as membranes, microchannel array, and microfluidic emulsification devices. Membrane and microchannel emul...This review focuses on recent developments in the fabrication of multiple emulsions in micro-scale systems such as membranes, microchannel array, and microfluidic emulsification devices. Membrane and microchannel emulsification offer great potential to manufacture multiple emulsions with uniform drop sizes and high encapsulation efficiency of encapsulated active materials. Meanwhile, microfluidic devices enable an unprecedented level of control over the number, size, and type of internal droplets at each hierarchical level but suffer from low production scale. Microfluidic methods can be used to generate high-order multiple emulsions （triple, quadruple, and quintuple）, non-spherical （discoidal and rod-like） drops, and asymmetric drops such as Janus and ternary drops with two or three distinct surface regions. Multiple emulsion droplets generated in microfabricated devices can be used as templates for vesicles like polymersomes, liposomes, and colloidosomes with multiple inner compartments for simultaneous encaosulation and release of incomoatible active materials or reactants.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos.52106114,51725602,and 52036006)。
文摘Droplet-based high heat flux dissipation technique under multi-gravitational environments has gained increasing research attention due to the increased requirements of heat dissipation in advanced air-/space-borne electronics.In this paper,a threedimensional model was developed to investigate the impact of continuous droplets on liquid film under various Weber numbers and gravity loads.In other words,the effects of Weber number and gravity load on the flow and heat transfer characteristics were investigated.The results demonstrated that the dissipated heat flux was positively correlated with both Weber number and gravity load.A large Weber number indicated larger kinetic energy of a droplet,leading to a greater disturbance on the impacted film area.When the Weber number was doubled,the average wall heat flux could be enhanced by 36.3%.In addition,the heat flux could be boosted by 5.4%when the gravity load ranged from 0 to 1g.Moreover,a weightless condition suppressed the vapor escape rates on the heating wall where the volume fraction of the vapor on the wall could increase by 20%under 0g,leading to deteriorated heat transfer performance.The novelty in this paper lies in the accurate three-dimensional modeling of an aerospaceoriented droplet impacting two-phase heat transfer and fluid dynamics,associating macro-scale thermal performance to microscale thermophysics mechanisms.The findings of this study could guide the development of aerospace-borne spray cooling facilities for advanced aerospace thermal management.
文摘This review focuses on recent developments in the fabrication of multiple emulsions in micro-scale systems such as membranes, microchannel array, and microfluidic emulsification devices. Membrane and microchannel emulsification offer great potential to manufacture multiple emulsions with uniform drop sizes and high encapsulation efficiency of encapsulated active materials. Meanwhile, microfluidic devices enable an unprecedented level of control over the number, size, and type of internal droplets at each hierarchical level but suffer from low production scale. Microfluidic methods can be used to generate high-order multiple emulsions （triple, quadruple, and quintuple）, non-spherical （discoidal and rod-like） drops, and asymmetric drops such as Janus and ternary drops with two or three distinct surface regions. Multiple emulsion droplets generated in microfabricated devices can be used as templates for vesicles like polymersomes, liposomes, and colloidosomes with multiple inner compartments for simultaneous encaosulation and release of incomoatible active materials or reactants.
