Heat Transfer Enhancement Accompanying Leidenfrost State Suppression at Ultrahigh Temperatures

Abstract

The well-known Leidenfrost effect is the formation of a vapor layer between a liquid and an underlying hot surface. This insulating vapor layer severely degrades heat transfer and results in surface dryout. We measure the heat transfer enhancement and dryout prevention benefits accompanying electrostatic suppression of the Leidenfrost state. Interfacial electric fields in the vapor layer can attract liquid toward the surface and promote wetting. This principle can suppress dryout even at ultrahigh temperatures exceeding 500 °C, which is more than 8 times the Leidenfrost superheat for organic solvents. Robust Leidenfrost state suppression is observed for a variety of liquids, ranging from low electrical conductivity organic solvents to electrically conducting salt solutions. Elimination of the vapor layer increases heat dissipation capacity by more than 1 order of magnitude. Heat removal capacities exceeding 500 W/cm(2) are measured, which is 5 times the critical heat flux (CHF) of water on common engineering surfaces. Furthermore, the heat transfer rate can be electrically controlled by the applied voltage. The underlying science is explained via a multiphysics analytical model which captures the coupled electrostatic-fluid-thermal transport phenomena underlying electrostatic Leidenfrost state suppression. Overall, this work uncovers the physics underlying dryout prevention and demonstrates electrically tunable boiling heat transfer with ultralow power consumption.

Self-organized oscillations of Leidenfrost drops

“…The Leidenfrost effect can be easily observed by placing a water drop onto a hot pan over a cook stove in the kitchen, and has been the subject of numerous fundamental and applied studies due to the complex and rich interactions between the solid, liquid, and vapor phases (Quéré 2013). Examples include the evaporation dynamics and geometry of the drop (Burton et al 2012;Biance et al 2003;Myers & Charpin 2009;Pomeau et al 2012;Xu & Qian 2013;Sobac et al 2014;Hidalgo-Caballero et al 2016;Maquet et al 2016;Wong et al 2017), the stability of the vapor-liquid interface (Duchemin et al 2005;Lister et al 2008;Snoeijer et al 2009;Bouwhuis et al 2013;Trinh et al 2014;Raux et al 2015;Maquet et al 2015), hydrodynamic drag-reduction (Vakarelski et al 2011(Vakarelski et al , 2012(Vakarelski et al , 2014, self-propulsion of droplets (Linke et al 2006;Dupeux et al 2011b,a;Lagubeau et al 2011;Cousins et al 2012;Li et al 2016;Soto et al 2016;Sobac et al 2017), impact dynamics (Biance et al 2006;Tran et al 2012;Castanet et al 2015;Shirota et al 2016), green nanofabrication (Abdelaziz et al 2013), chemical reactions (Bain et al 2016), fuel combustion (Kadota et al 2007), quenching process in metallurgy (Bernardin & Mudawar 1999), heat transfer (Talari et al 2018;Shahriari et al 2014), directional...…”

Acoustic detection of electrostatic suppression of the Leidenfrost state

“…There is significant literature on different aspects of the Leidenfrost effect including geometry of the droplet [9,10], droplet oscillations [11][12][13][14][15], self-propulsion of Leidenfrost droplets and Leidenfrost state-based drag reduction [16][17][18][19]. Recent studies show that an externally applied electric field in the vapor gap fundamentally eliminates [20][21][22][23][24][25][26][27] the Leidenfrost state by electrostatically attracting the droplet towards the surface. Both Direct Current (DC) [22][23][24][25][26] and Alternating Current (AC) [27] fields have been used for Leidenfrost state suppression on solid and liquid surfaces.…”

“…Recent studies show that an externally applied electric field in the vapor gap fundamentally eliminates [20][21][22][23][24][25][26][27] the Leidenfrost state by electrostatically attracting the droplet towards the surface. Both Direct Current (DC) [22][23][24][25][26] and Alternating Current (AC) [27] fields have been used for Leidenfrost state suppression on solid and liquid surfaces.…”

“…One limitation in such studies is the reliance on visual and optical measurements to infer the physics underlying suppression. In our earlier studies [22,25,27] high speed imaging was used to detect instabilities at the liquid-vapor interface, which indicate suppression. Celestini et al [20] used interferometry in their study on electrical suppression.…”

“…This wire restricts droplet mobility and electrically biases the droplet; the substrate is electrically grounded. Suppression was visualized with a high-speed camera, as in previous studies [22,27]. All experiments were repeated and the reported results are the average of at least 4 measurements.…”