Multi-scale Control and Enhancement of Reactor Boiling Heat Flux by Reagents and Nanoparticles

Manglik, R M ; Athavale, A ; Kalaikadal, D S ; Deodhar, A ; Verma, U

关键词: ADDITIVES;    BOILING;    BUBBLE GROWTH;    BUBBLES;    COALESCENCE;    ELECTRODYNAMICS;    EVAPORATION;    HEAT FLUX;    HEAT TRANSFER;    HYPOTHESIS;    MANAGEMENT;    NUCLEATE BOILING;    NUCLEATION;    PHYSICS;    POLYMERS;    RHEOLOGY;    SURFACTANTS;    TRANSIENTS;    TRANSPORT;    WATER;   

DOI  :  10.2172/1024386
RP-ID  :  DOE/ID/14772
PID  :  OSTI ID: 1024386
Others  :  TRN: US201119%%347

美国|英语

来源: SciTech Connect

【 摘 要 】

The phenomenological characterization of the use of non-invasive and passive techniques to enhance the boiling heat transfer in water has been carried out in this extended study. It provides fundamental enhanced heat transfer data for nucleate boiling and discusses the associated physics with the aim of addressing future and next-generation reactor thermal-hydraulic management. It essentially addresses the hypothesis that in phase-change processes during boiling, the primary mechanisms can be related to the liquid-vapor interfacial tension and surface wetting at the solidliquid interface. These interfacial characteristics can be significantly altered and decoupled by introducing small quantities of additives in water, such as surface-active polymers, surfactants, and nanoparticles. The changes are fundamentally caused at a molecular-scale by the relative bulk molecular dynamics and adsorption-desorption of the additive at the liquid-vapor interface, and its physisorption and electrokinetics at the liquid-solid interface. At the micro-scale, the transient transport mechanisms at the solid-liquid-vapor interface during nucleation and bubblegrowth can be attributed to thin-film spreading, surface-micro-cavity activation, and micro-layer evaporation. Furthermore at the macro-scale, the heat transport is in turn governed by the bubble growth and distribution, macro-layer heat transfer, bubble dynamics (bubble coalescence, collapse, break-up, and translation), and liquid rheology. Some of these behaviors and processes are measured and characterized in this study, the outcomes of which advance the concomitant fundamental physics, as well as provide insights for developing control strategies for the molecular-scale manipulation of interfacial tension and surface wetting in boiling by means of polymeric reagents, surfactants, and other soluble surface-active additives.