Use of Machine Learning Tools to Assess Surface Dryout During Nucleate and Transition Boiling on Surfaces With Different Wetting and Substrate Properties

2021 ◽  
Author(s):  
Ursan Tchouteng Njike ◽  
Samuel Cabrera ◽  
Emma R. McClure ◽  
Van P. Carey
Keyword(s):  
Machine Learning ◽  
Heat Flux ◽  
Nucleate Boiling ◽  
Learning Tools ◽  
Surface Wetting ◽  
Maximum Heat ◽  
Copper Surfaces ◽  
Boiling Range ◽  
Substrate Properties ◽  
Learning Analysis

Abstract The work reported in this paper explored the use of machine learning tools to analyze quenching pool boiling data in the nucleate boiling range, near maximum heat flux range, and through the transition boiling range towards the Leidenfrost (minimum heat flux) point. It specifically explores the hypothesis that this sequence is a consequence of progressive dryout of the surface as the wall superheat increases. Machine learning tools are used with a heuristic model of the dryout parametric dependence to extract information about the magnitude of surface dryout as the superheat increases. From experimental data, the machine learning analysis provides an indication of how the dryout transition differs for different surface wetting characteristics and substrate materials. The wetting variations considered ranged from moderately wetted plain aluminum and copper surfaces to highly wetted nanostructured superhydrophilic surfaces. The data examined included aluminum and copper substrates. The results of the machine learning analysis indicate that the properties of the surface substrate can have a significant effect on the progressive surface dryout. In contrast, the surface wetting characteristics had a more limited effect for the surfaces tested. The paper concludes with an assessment of the implications of the findings for developing enhanced surfaces for boiling heat transfer performance.

Use of Genetic Algorithms and Machine Learning to Explore Parametric Trends in Nucleate Boiling Heat Transfer Data

2020 ◽  
Author(s):  
Emma R. McClure ◽  
Van P. Carey
Keyword(s):  
Heat Transfer ◽  
Machine Learning ◽  
Heat Flux ◽  
Genetic Algorithms ◽  
Boiling Heat Transfer ◽  
Nucleate Boiling ◽  
Learning Tools ◽  
Transfer Data ◽  
Parametric Effects ◽  
Marangoni Effects

Abstract Exploring parametric effects in pool boiling is particularly challenging because the dependence of the resulting surface heat flux on many parameters is non-linear, and the mechanisms can interact in complex ways. Historically, parametric effects in nucleate boiling processes have most often been deduced by fitting relations obtained from physical models to experimental data, or looking for correlated trends in non-dimensionalized data. Using such approaches, observed trends are often influenced by the framing of the analysis that results from the modeling or the collection of dimensionless variables used. Machine learning strategies can be attractive alternatives because they can be constructed either to minimize biases or to emphasize specific biases that reflect knowledge of the physics of the system. The investigation summarized here explored the use of machine learning methods as a tool for determining parametric trends in boiling heat transfer data, and as a means for developing methods to predict boiling heat transfer. Results are presented that demonstrate how genetic algorithms and other machine learning tools can be used to extract heat flux dependencies on system parameters. A key element of the machine learning analysis process is preparation of the data used. Use of raw data and use of dimensionless rescaled data are explored, and the advantages and disadvantages of each are assessed. Data for nucleate boiling of a binary mixture are analyzed to determine the heat flux dependence on wall superheat, gravity, Marangoni effects and pressure. The results provide new insight into how gravity and Marangoni effects interact in boiling processes of this type. The results also demonstrate how machine learning tools can clarify how different mechanisms interact in the boiling process, as well as directly providing the ability to predict heat transfer performance for design of heat transfer devices that involve nucleate boiling. Potential use of machine learning tools on big data collections for nucleate boiling processes to more broadly assess parametric effects is also discussed.

High Heat Flux Phase Change on Silicon Wick Structures

2012 ◽  
Author(s):  
Qingjun Cai ◽  
Avijit Bhunia ◽  
Yuan Zhao
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Phase Change ◽  
Test Chamber ◽  
Nucleate Boiling ◽  
High Heat ◽  
High Heat Flux ◽  
Maximum Heat ◽  
Wick Structure ◽  
Silicon Pillars

Silicon is the major material in IC manufacture. It has high thermal conductivity and is compatible with precision micro-fabrication. It also has decent thermal expansion coefficient to most semiconductor materials. These characteristics make it an ideally underlying material for fabricating micro/mini heat pipes and their wick structures. In this paper, we focus our research investigations on high heat flux phase change capacity of the silicon wick structures. The experimental wick sample is composed of silicon pillars 320μm in height and 30 ∼ 100μm in diameter. In a stainless steel test chamber, synchronized visualizations and measurements are performed to crosscheck experimental phenomena and data. Using the mono-wick structure with large silicon pillar of 100μm in diameter, the phase change on the silicon wick structure reaches its maximum heat flux at 1,130W/cm2 over a 2mm×2mm heating area. The wick structure can fully utilize the wick pump capability to supply liquid from all 360° directions to the center heating area. In contrast, the large heating area and fine silicon pillars 10μm in diameter significantly reduces liquid transport capability and suppresses generation of nucleate boiling. As a result, phase change completely relies on evaporation, and the CHF of the wick structure is reduced to 180W/cm2. An analytical model based on high heat flux phase change of mono-porous wick structures indicates that heat transfer capability is subjected to the ratio between the wick particle radius and the heater dimensions, as well as vapor occupation ratio of the porous volume. In contrast, phase change heat transfer coefficients of the wick structures essentially reflect material properties of wick structure and mechanism of two-phase interactions within wick structures.

RELAP5-3D Sensitivity Studies of Incorporating Axial Boron Gradients Into a Heater Tube Experiment for Pool Boiling CHF Testing in TREAT

2020 ◽  
Author(s):  
Richard Hernandez ◽  
Nicholas R. Brown ◽  
Charles P. Folsom ◽  
Nicolas E. Woolstenhulme ◽  
Colby B. Jensen
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
National Laboratory ◽  
Pool Boiling ◽  
Nucleate Boiling ◽  
Coupling Factor ◽  
Design Parameters ◽  
Coolant Temperature ◽  
Axial Region ◽  
Maximum Heat

Abstract Nuclear reactor designs are governed by postulated accident events that may occur during their operational lifetime. One type of incident is a reactivity-initiated accident (RIA), during which a sudden surge of power in the fuel components within the core may result in the latter exceeding its cooling capabilities. This could lead to a departure from nucleate boiling (DNB) event which results in a significant decrease in heat transfer capabilities. Preventing the occurrence of a DNB crisis requires a fundamental understanding of the cladding-to-coolant heat transfer under fast transient conditions, as well as the governing hydrodynamic and design parameters that influence when the critical heat flux (CHF) will be exceeded. Presently, large uncertainties in computer models used to predict CHF have led to conservative safety limits governing light-water reactor (LWR) designs. The Idaho National Laboratory (INL) is currently leading a combined effort that takes advantage of the restart of the Transient Reactor Test (TREAT) facility, to better understand the mechanism of CHF under in-pile pool boiling conditions. The goal of this laboratory directed project is to use the unique capabilities of TREAT coupled with a non-fueled nuclear heated borated stainless-steel 304 tube experiment within an experimental capsule. The borated tube will induce CHF in the surrounding coolant when subjected to a power pulse within the TREAT. The impacts of rapid surface heating effects as well as radiation-induced surface activation (RISA) will be experimentally investigated. This feature is a continuation to previous thermal hydraulics analysis that was conducted to inform on a test matrix for the design of the borated heater experiment. The borated tube was used in place of a solid rod so that the center axial region can be instrumented to allow for better experimental analysis. Therefore, it is desirable to design this rodlet so that the maximum heat flux occurs at the center of the axial length of the rod. The work presented here analyzes the potential to integrate axial boron gradients within this tube to shape its power curve. Several generic axial power shapes were initially considered. Natural boron concentrations between 0.1–2.0 wt.% were analyzed and a power coupling factor (PCF) was calculated for each. A self-shielding study was conducted to develop radial power profiles for several boron concentrations. These were then applied to three different power pulses to determine how these two parameters influence the chosen axial heat flux curve. Variations in the initial coolant temperature were investigated. Lastly, how the shape of the generic curve is affected following a DNB event was also studied. Two different CHF cases were included within the scope of this analyses; one during which CHF was exceeding along the entire axial region of the rod, and another where the former occurred at the center region only. The behavior of the curve overtime was investigated.

Boiling Heat Transfer Characteristics of Staggered-array Water Impinging Jets on Hot Steel Plate

2018 ◽  
Vol 140 (3) ◽  
Author(s):  
Sang Gun Lee ◽  
Jin Sub Kim ◽  
Dong Hwan Shin ◽  
Jungho Lee
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Surface Temperature ◽  
Boiling Heat Transfer ◽  
Steel Plate ◽  
Nucleate Boiling ◽  
Impinging Jets ◽  
Heat Transfer Characteristics ◽  
Maximum Heat ◽  
Maximum Heat Flux

The effect of staggered-array water impinging jets on boiling heat transfer was investigated by a simultaneous measurement between boiling visualization and heat transfer characteristics. The boiling phenomena of staggered-array impinging jets on hot steel plate were visualized by 4K UHD video camera. The surface temperature and heat flux on hot steel plate was determined by solving 2-D inverse heat conduction problem, which was measured by the flat-plate heat flux gauge. The experiment was made at jet Reynolds number of Re = 5,000 and the jet-to-jet distance of staggered-array jets of S/Dn = 10. Complex flow interaction of staggered-array impinging jets exhibited hexagonal flow pattern like as honey-comb. The calculated surface heat transfer profiles show a good agreement with the corresponding boiling visualization. The peak of heat flux accords with the location which nucleate boiling is occurred at. In early stage, the positions of maximum heat flux locate at the stagnation point of each jet as the relatively low surface temperature is shown at their positions. At the elapsed time of 10 s, the flat shape of heat flux profile is formed in the hexagonal area where the interacting flow uniformly cools down the wetted surface. After that, the wetted area continuously enlarges with time and the maximum heat flux is observed at its peripheral. These results point out that the flow interaction of staggered-array jets effectively cools down the closer area around jets and also show an expansion of nucleate boiling and suppression of film boiling during water jet cooling on hot steel plate. [This work was supported by the KETEP grant funded by the Ministry of Trade, Industry & Energy, Korea (Grant No. 20142010102910).]

Wetting Front Tracking During Metal Quenching Using Array of Jets

2010 ◽  
Author(s):  
Khalid H. M. Abdalrahman ◽  
Umair Alam ◽  
Eckehard Specht
Keyword(s):  
Heat Flux ◽  
Nucleate Boiling ◽  
Temperature Data ◽  
Film Boiling ◽  
Wetting Front ◽  
Inverse Algorithm ◽  
Maximum Heat ◽  
Water Jets ◽  
Maximum Heat Flux ◽  
Hot Surface

Metal quenching is a commonly used heat treatment technique, e.g. Direct Chill aluminum casting, quenching of steel for obtaining desired micro-structures. Film boiling, transition boiling, nucleate boiling and forced convection are the mechanisms of heat transfer during quenching. When the coolant strikes the hot metal surface during quenching, the surface can be divided into two distinct zones which are dry and wet zones. Heat transfer in dry zone is dominated by film boiling and the wet zone is influenced by transition boiling, nucleate boiling and forced convection. Wetting front is the boundary zone which separates the dry and wet regions. Wetting front is a thin region of coolant in which the transition and nucleate boiling occurs. Within a wetting front, the heat flux leaving from the hot surface reaches it global maximum. The speed of the wetting front indicates the quench ability of the hot surface for the corresponding flow conditions and the coolant. Wetting front tracking is more important for the prediction of surface temperature during quenching. This research works presents the combined numerical and experimental aspects of the heat flux estimation during the quenching process. At any instant, the position of the wetting front is simply assumed as the location of maximum heat flux. This assumption implicitly treats the wetting front as a line instead of area. The location of wetting front and its velocity at every instant are determined by using the experimental temperature data and the inverse algorithm. Experimental setup and temperature measurement technique are explained in detail. The developed inverse algorithm predicts the quenched side temperature and heat flux from the measured side temperature. A two-dimensional Inverse Heat Conduction Problem (IHCP) is solved through the non iterative Finite Element Method (FEM). The considered quenching technique for the study, based on the method of coolant supplied which is array of water jets. One kind of coolant used in this study is tap water. Aluminum 2024, Inconel, and Nickel are the three different materials considered for the analysis. A rectangular plate made of Nickel with dimension 140 × 70 × 2 mm, using the same dimensions of the Inconel. As in the case of the use of Aluminum, the thickness is the only change to 3 mm, the plate quenched by array of water jets with velocities 0.9 m/s, 1.2 m/s, 1.5 m/s and 1.8 m/s. The measured temperature data are further processed through the inverse finite element technique for the estimation of heat flux leaving from the quenched surface. The position of maximum heat flux changes with time which indicates the movement of wetting front. In this work, four different coolant velocities are employed, and the change in coolant velocity strongly affects the heat flux and wetting front movement.

Microporous Coatings to Maximize Pool Boiling Heat Transfer of Saturated R-123 and Water

2015 ◽  
Vol 137 (8) ◽  
Author(s):  
Joo Han Kim ◽  
Ajay Gurung ◽  
Miguel Amaya ◽  
Sang Muk Kwark ◽  
Seung M. You
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Nucleate Boiling ◽  
Transfer Coefficients ◽  
Maximum Heat ◽  
Microporous Coating ◽  
Plain Surface ◽  
Improved Performance

The present research is an experimental study for the enhancement of boiling heat transfer using microporous coatings. Two types of coatings are investigated: one that is bonded using epoxy and the other by soldering. Effects on pool boiling performance were investigated, of different metal particle sizes of the epoxy-based coating, on R-123 refrigerants, and on water. All boiling tests were performed with 1 cm × 1 cm test heaters in the horizontal, upward-facing orientation in saturated conditions at atmospheric pressure and under increasing heat flux. The surface enhanced by the epoxy-based microporous coatings significantly augmented both nucleate boiling heat transfer coefficients and critical heat flux (CHF) of R-123 relative to those of a plain surface. However, for water, with the same microporous coating, boiling performance did not improve as much, and thermal resistance of the epoxy component limited the maximum heat flux that could be applied. Therefore, for water, to seek improved performance, the solder-based microporous coating was applied. This thermally conductive microporous coating, TCMC, greatly enhanced the boiling performance of water relative to the plain surface, increasing the heat transfer coefficient up to ∼5.6 times, and doubling the CHF.

Heat Transfer From a Small Heated Region to R-113 and FC-72

1989 ◽  
Vol 111 (4) ◽  
pp. 1053-1059 ◽  
Author(s):  
K. R. Samant ◽  
T. W. Simon
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Quartz Substrate ◽  
Rectangular Channel ◽  
Nucleate Boiling ◽  
Decomposition Temperature ◽  
Large Temperature ◽  
Resistance Thermometer ◽  
Maximum Heat ◽  
Heater Element

An experimental investigation of heat transfer from a small heated patch to a subcooled, fully developed turbulent flow is conducted. The test patch, approximately 0.25 mm long and 2.0 mm wide, is located on the floor of a small rectangular channel through which a coolant (R-113 or FC-72) is circulated. A thin film of Nichrome deposited on a quartz substrate serves as an integrated heater element and resistance thermometer. The maximum achievable heat flux with R-113, limited by the thermal decomposition temperature of the fluid, is 2.04 MW/m2 at a bulk velocity of 1.8 m/s and a high wall superheat of 80° C. The results obtained with FC-72 show large temperature excursions at the onset of nucleate boiling and a boiling hysteresis near the onset of nucleate boiling. These effects decrease with increasing velocity and/or subcooling. The heat flux at departure from nucleate boiling increases with increasing velocity and/or subcooling. A maximum heat flux of 4.26 MW/m2 at departure from nucleate boiling is observed.

Effect of Heat Flux on Bubble Coalescence Phenomena and Sound Signatures During Pool Boiling

2020 ◽  
Author(s):  
Akshat Negi ◽  
Aniket M. Rishi ◽  
Satish G. Kandlikar
Keyword(s):  
Heat Flux ◽  
Pool Boiling ◽  
Nucleate Boiling ◽  
Bubble Nucleation ◽  
Frequency Region ◽  
Heat Fluxes ◽  
Working Fluid ◽  
Bubble Collapse ◽  
Maximum Heat ◽  
Acoustic Signatures

Abstract Boiling heat transfer is extensively used in various industrial applications to efficiently dissipate a large amount of heat by maintaining lower surface temperatures. The maximum heat flux dissipated during boiling is limited by the critical heat flux (CHF) and limited visualization of the boiling surface limits the identification of the impending CHF condition to rely on temperature monitoring alone. The study presented here focuses on developing a method for analyzing and identifying acoustic signatures throughout the nucleate boiling regimes that are indicative of the boiling state of the heater surface. The bubble nucleation and coalescence along with bubble collapse at the liquid-vapor interface leads to variation in acoustic emission patterns during boiling. These sound waves are studied and acoustic signatures that are representative of the impending CHF are identified over plain and enhanced copper substrates with water as the working fluid. During pool boiling study, it was observed that sound was dominant in two frequency regions (400–500 Hz dominant throughout nucleate boiling and 100–200 Hz dominant at heat fluxes > 100 W/cm2). However, just before CHF, a sudden drop in amplitude was observed in the high frequency region (400–500 Hz), while the amplitude in low frequency region (100–200 Hz) continued to rise. It was concluded that this acoustic study can be used as a tool to predict the approaching CHF condition.

Subcooled Flow Boiling in a Minichannel

2009 ◽  
Author(s):  
Akira Oshima ◽  
Koichi Suzuki ◽  
Chungpyo Hong ◽  
Masataka Mochizuki
Keyword(s):  
Heat Flux ◽  
High Speed ◽  
Flow Boiling ◽  
Heating Surface ◽  
Nucleate Boiling ◽  
High Heat Flux ◽  
Subcooled Flow Boiling ◽  
Maximum Heat ◽  
High Speed Video ◽  
Subcooled Flow

It has been considered that the dry-out is easy to occur in boiling heat transfer for a small channel, a mini or microchannel because the channel was easily filled with coalescing vapor bubbles. In the present study, the experiments of subcooled flow boiling of water were performed under atmospheric condition for a horizontal rectangular channel of which size is 1mm in height and 1mm in width with a flat heating surface of 10mm in length and 1mm in width placed on the bottom of the channel. The heating surface is a top of copper heating block and heated by ceramics heaters. In the high heat flux region of nucleate boiling, about 70 ∼ 80 percent of heating surface was covered with a large coalescing bubble and the boiling reached critical heat flux (CHF) by a high speed video observation. In the beginning of transition boiling, coalescing bubbles were collapsed to many fine bubbles and microbubble emission boiling was observed at higher liquid subcooling than 30K. The maximum heat flux obtained was 8MW/m2 (800W/cm2) at liquid subcooling of higher than 40K and the liquid velocity of 0.5m/s. However, the surface temperature was extremely higher than that of centimeter scale channel. The high speed video photographs indicated that microbubble emission boiling occurs in the deep transition boiling region.

Saturation Boiling Critical Heat Flux of PF-5060 Dielectric Liquid on Microporous Copper Surfaces

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Mohamed S. El-Genk ◽  
Amir F. Ali
Keyword(s):  
Heat Flux ◽  
Critical Heat Flux ◽  
Inclination Angle ◽  
Nucleate Boiling ◽  
Dielectric Liquid ◽  
Copper Surfaces ◽  
Inclination Angles ◽  
Surface Inclination ◽  
Effect Of Surface ◽  
Good Agreement

Pool boiling experiments are performed to investigate potential enhancement of critical heat flux (CHF) of PF-5060 dielectric liquid on microporous copper (MPC) surfaces and the effect of surface inclination angle. The morphology and microstructure of the MPC surfaces change with thickness. The experiments tested seven 10 × 10 mm MPC surfaces with thicknesses from 80 to 230 μm at inclination angles of 0 deg (upward facing), 60 deg, 90 deg (vertical), 120 deg, 150 deg, 160 deg, 170 deg, and 180 deg (downward facing). CHF increases as the thickness of the surface increases and/or the inclination angle decreases. The values in the upward facing orientation are 36–59% higher than on smooth Cu. For all surfaces, CHF values in the downward facing orientation are approximately 28% of those in the upward facing orientation. A developed CHF correlation, similar to those of Zuber and Kutateladze, accounts for the effects of inclination angle and thickness of the MPC surfaces. It is in good agreement with experimental data to within ±8%. Still photographs of nucleate boiling on the MPC surfaces at different inclinations help the interpretation of the experimental results.

Sign in / Sign up

Export Citation Format

Share Document