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[Display omitted] Despite the flourishing studies of droplet interfacial boiling, the boiling upon vibratory surfaces, which may cause vigorous liquid–vapor-solid interactions, has rarely been investigated. Enhanced boiling normally can be gained from rapid removal of vapor and disturbance of liquid–vapor interface. We hypothesize that the vibratory surfaces enhance both effects with new intriguing phenomena and thus, attain an enhanced boiling heat transfer. We experimentally investigated the impacting fluid dynamics and coupled heat transfer patterns of multiple droplets and a single droplet impinging on still and vibratory surfaces of various materials and different wettability. The boiling under vibratory surfaces with increased vibration velocity amplitude and enhanced wettability can be enhanced by 80% in heat transfer coefficient and Nusselt number, which is attributed to several reasons: shortened bubble lifespan, thinner and smaller bubbles, and enhanced disturbances in liquid–vapor interfaces. The vibration also delays the Leidenfrost point when the droplet impacts a descending surface, which shows that the droplet impact moment (vibration phase angle) is particularly crucial. The descending surface releases the generated vapor actively and facilitates liquid–solid contact, thereby delaying the Leidenfrost. From fundamentals to application, this article strengthens our understanding of vibrated interfacial boiling in scenarios closer to multiple natural processes and practical industries. [ABSTRACT FROM AUTHOR]

This paper presents an air-oriented spray cooling system (SCS) integrated with a two-phase ejector for the thermal management system. Considering its aeronautical application, the spray nozzle in the SCS is an air-blast one. Heat transfer performance (HTP) of air-water spray cooling was studied experimentally on the basis of the ground-based test. Factors including pressure difference between water-inlet-pressure (WIP) and spray cavity one (PDWIC) and the spray volumetric flow rate (SVFR) were investigated and discussed. Under a constant operating condition, the cooling capacity can be promoted by the growth factors of the PDWIC and SVFR with the values from 51.90 kPa to 235.35 kPa and 3.91 L ⋅ h − 1 to 14.53 L ⋅ h − 1 , respectively. Under the same heating power, HTP is proportional to the two dimensionless parameters Reynolds number and Weber number due to the growth of droplet-impacting velocity and droplet size as the increasing of PDWIC or SVFR. Additionally, compared with the factor of the droplet size, the HTP is more sensitive to the variation in the droplet-impacting velocity. Based on the experimental data, an empirical experimental correlation for the prediction of the dimensionless parameter Nusselt number in the non-boiling region with the relative error of only ± 10 % was obtained based on the least square method. [ABSTRACT FROM AUTHOR]

Spray cooling is believed to be a promising candidate for the cooling of the next-generation high heat-flux electronics. Different from the traditional spray cooling (SC), a modified version of SC – immersed spray cooling (ISC) – is firstly proposed in this paper. Experimental set-up upon which thermal tests of SC, ISC and pool boiling can be conducted was established. In order to realize the multifunction of the experimental system, an ejector, which plays an important role to control the liquid level in the cooling chamber, is integrated in the experimental system. Based on the novel theory of suction according to the need, modelling, design, and fabrication of the ejector was conducted, which proves to be a success in the practical operation. We experimentally demonstrated that the ISC performs the best in terms of cooling performance in all the operating conditions. Comparative study between thermal performances between SC and ISC is the focus in this paper. A maximum 65.6% enhancement in heat flux was observed for the ISC when the surface temperature was 205.6 °C. The enhanced heat transfer of the ISC can be attained due to the vapor layer elimination and chaotic effect around the target surface. [ABSTRACT FROM AUTHOR]