The influence of additive microstructures on the heat transfer crisis in a two-phase system with a local heating source

2019 ◽  
Author(s):  
Karapet S. Eloyan ◽  
Fedor V. Ronshin ◽  
Vyacheslav V. Cheverda
Keyword(s):  
Heat Transfer ◽  
Local Heating ◽  
Phase System ◽  
Two Phase ◽  
Heat Transfer Crisis ◽  
Heating Source

scholarly journals Dynamics of dry spots in the liquid film moved by the gas flow in the mini-channel under intensive local heating

2018 ◽  
Vol 194 ◽  
pp. 01059
Author(s):  
Egor Tkachenko
Keyword(s):  
Heat Transfer ◽  
High Speed ◽  
Gas Flow ◽  
Local Heating ◽  
Experimental Studies ◽  
Heater Surface ◽  
Two Phase ◽  
Heat Transfer Crisis ◽  
Typical Size ◽  
Dry Spot

Experimental studies of hydrodynamics and the heat transfer crisis were carried out for a two-phase stratified flow in a mini-channel with intensive heating from a heat source of 1x1 cm2. It has been established that as the heat flow increases, the total area of dry spots on the heater increases, but when a certain temperature of the heater surface reaches ≈100 °C, the area of dry spots begins to decrease. With the help of high-speed visualization (shooting speed 100000 frames per second), several stages of formation of a dry spot (a typical size of the order of 100 microns) were isolated. It was found that at a heat flux of 450 W/cm2 about 1 million dry spots per 1 second are formed and washed on the surface of the heater (1 cm2). The speed of the contact line when dry spot is forming reaches 10 m/s.

Thermal Model of the Package Integrated Cyclone COoler (PICCO): Achieving High Thermal Conductance Using Swirled Two-Phase Flow

2020 ◽  
Author(s):  
Rinaldo L. Miorini ◽  
Darin J. Sharar ◽  
Peter deBock
Keyword(s):  
Heat Transfer ◽  
Heat Dissipation ◽  
Heat Conduction Problem ◽  
Thermal Conductance ◽  
Radial Pressure ◽  
High Heat ◽  
Phase System ◽  
Two Phase ◽  
Radial Acceleration ◽  
Us Army

Abstract The demand for high power density, therefore high heat dissipation, power electronics modules is propelled by applications such as hybrid transportation and asynchronous power generation, among others. Besides a low thermal resistance, these applications require high thermal capacitance to manage transient operations. The Package Integrated Cyclone COoler (PICCO) is an additively manufactured, thermal energy storing cooler codesigned by GE Research (GRC) in collaboration with the US Army Research Lab (ARL). The key aspect of PICCO is its capability to swirl a two-phase coolant, i.e. liquid-gas. The centrifugal field creates a radial pressure gradient inducing buoyancy. The strong radial acceleration to which the fluid is subject forces relatively cold flow outward to reach the hot wall, thus boosting the heat transfer, while hot flow and bubbles migrate inward and the two-phase system is nearly isothermal (thermal storage). The proposed study models the swirled flow in terms of liquid film heat conductance and critical heat flux predictions. The resulting heat transfer coefficient can be applied to the walls of the cyclone and used as a boundary condition for the heat conduction problem through the cyclone wall and the module layers.

scholarly journals Problems of Reliability Indicators Increase of Critical Heat Flux Calculations in the Water-Cooled Nuclear Reactors Based on the Computer Thermal-Hydraulic Codes

2018 ◽  
pp. 16-22
Author(s):  
G. Sharaevsky
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Critical Heat Flux ◽  
Nuclear Reactors ◽  
Thermal Flux ◽  
Calculated Data ◽  
Two Phase ◽  
Water Steam ◽  
Heat Transfer Crisis ◽  
Computer Codes

The analysis of the current state of research and developments in the field of creation of thermal-hydraulic computer codes has been performed. The experience of creation of foreign versions of best-estimate codes was analyzed. Considerable attention is paid to the issue of critical heat flux calculation of nuclear reactors channels. It is demonstrated that now the efficiency of application of modern computer codes for estimating of the heat transfer crisis in the water-cooled nuclear reactors requires further improvement. Calculation methods for accuracy increase of predicting this thermal-hydraulic phenomenon in reactor channels are considered. The well-known methods of critical thermal flux in nuclear reactors channels have been analyzed. Peculiarities of determination of the heat transfer crisis in the forced of the vapor-water steam motion have been reviewed. Adequacy of software computer codes designed to calculate the main safety parameters of water-cooled nuclear reactors was analyzed. The idea of the physical mechanism of the heat transfer crisis under forced motion of a two-phase flow in heated channels was considered. Particular attention has been paid to analysis of experimental and calculated data on conditions of initiation of a heat transfer crisis in fuel assemblies rods.

Investigation of Microwave Field Selective Heating on Two-Phase System

2013 ◽  
Vol 448-453 ◽  
pp. 3005-3008
Author(s):  
Jian Yu Xing ◽  
Xiu Ling Song ◽  
Bo Bai ◽  
Shao Kun Lu ◽  
Hai Peng Liu
Keyword(s):  
Heat Transfer ◽  
Microwave Field ◽  
Reaction Times ◽  
Power Input ◽  
Heating Process ◽  
Phase System ◽  
Dielectric Heating ◽  
Distillation Process ◽  
Two Phase ◽  
Selective Heating

Microwaves represent an alternative way of power input into distillation process. Through dielectric heating, reaction mixtures are homogenously heated without contact to a wall. Reaction times are significantly reduced compared to conventionally (thermally) heated systems while maintaining selectivity. In this paper, microwave field select heating on two-phase system has been investigated numerically and experimentally. Temperature increasing, heat transfer and evaporation during heating process were analyzed. The possibility of microwave used for distillation was examined and proposed.

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