A New Electromagnetic Heating Method to Study Spray Cooling
-
M.E. Huerta-Larumbe
Abstract
This work shows measured heat fluxes that are removed by air-mist jets under steady-state conditions from different metallic surfaces at temperatures up to 1,200°C. A sample disk is subjected simultaneously to induction heating and spray cooling. In order to reach a set-point temperature for the disk, a digital controller adjusts the power delivered by a 5 kW high-frequency generator to compensate the heat removed by the spray. The heat flux removed by the impinging jet is determined from the measured values of coil current and disk temperature, and from the coupled numerical solution of the Maxwell’s equations together with the heat conduction equation. This method determines heat fluxes within 10% uncertainty. The obtained boiling curves for Pt, Ni and Inconel show that heat flux is described by a single curve in the stable film boiling regime for these metals.
Funding statement: Funding: Consejo Nacional de Ciencia y Tecnología 183161.
Acknowledgments
The authors are grateful to the National Council of Science and Technology of Mexico (CONACYT) for financial support through Grant 183161. MEHL wishes to thank CONACYT for his scholarship grant.
Nomenclature
Normal air flow rate (0°C, 105 Pa) through the nozzle [NL/s]
Magnetic vector potential [Vs/m]
Biot number (=
Magnetic flux density vector [T]
- CHF
Critical heat flux [MW/m2]
Volume mean diameter of droplets in the spray [μm]
Nominal diameter of metallic disk [mm]
Heat flux uncertainty [MW/m2]
Current frequency [kHz]
Magnetic field vector [A/m]
Heat transfer coefficient; and coefficient for combined boiling convection plus radiation [W/m2 K]
Heat transfer coefficient for natural convection to the environment surrounding the ceramic body; and for radiation [W/m2 K]
Magnitude of time-harmonic electric current; computed and measured Root Mean Square (RMS) electric current passing through the coil [A]
Computed RMS current in turns 1 and 2 of coil [A]
Imaginary unit number (= √–1)
Vector and magnitude of time-harmonic current density [A/m2]
Local thermal conductivity; and conductivity of Cu and Pt [W/mK]
Manometric air pressure in the line connected to the nozzle [kPa]
Rate of combined heat transfer by natural convection plus radiation through exposed surface of disk [W]
Consumed electric power by the generator [W]
Rate of heat flow to the coil [W]
- Re()
Operator that takes the real part of a complex number
Length of discretized closed circuit [m]
Mutual inductance [H]
Number of independent variables
Boiling convection heat flux; combined boiling convection plus radiation heat flux from exposed surface; radiation heat flux [MW/m2]
Local heat source resulting from Joule heating [W/m3]
Axi-symmetrical coordinates measured from the metallic disk center [m]
Total cross section area for current flow in each conductor [m2]
Temperature; computed and measured control temperatures [oC]
Temperatures of exposed hot surface; spray; and average of narrow ceramic bridge [oC]
- TDS
Total dissolved solids in water [ppm]
Volume weighted mean of x and z-velocity components [m/s]
Voltage drops applied to a closed circuit; to coil turn 1; and coil turn 2 [V]
Local water impact density [L/m2 s]
Water flow rate through the nozzle [L/s]
Rectangular coordinates with origin at center of sample surface [m]
Independent variables
Setback distance of nozzle exit from impingement surface [m]
- Greek
Measurement error of independent variable xi
Thickness of the metallic disk [mm]
Emissivity
Electromagnetic heating efficiency
Absolute magnetic permeability [H/m]
Constant, 3.14159264...
Electric conductivity [S/m]; Stefan-Boltzmann constant, 5.669 × 10–8 [W/m 2K4]
Current frequency,
- Subindex
Imaginary; real parts of a complex number
Integer denoting a discretized electric circuit within a conductor
Angular direction in cylindrical coordinates
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©2015 by De Gruyter
Articles in the same Issue
- Frontmatter
- Preface
- Experimental and Stochastic Modeling of the Globular Microstructure and the Microsegregation Evolution during the Solidification of Magnesium Alloys Cast at Low Superheat via Containerless Melting
- On the Influences of Adjacent Conducting Media and Coil Frequency on the Electromagnetic Field and Flow Characteristics in Solidifying Melts
- Nucleation of Carbon Monoxide Gas Bubbles in Electromagnetically Levitated Molten Iron Drops
- Numerical Analysis of Electromagnetic Levitation Employing Meshless Method Based on Weighted Least Square Method
- Arrays of Rotating Permanent Magnet Dipoles for Stirring and Pumping of Liquid Metals
- Flow Visualization by Means of Contactless Inductive Flow Tomography in the Presence of a Magnetic Brake
- CFD of the MHD Mold Flow by Means of Hybrid LES/RANS Turbulence Modeling
- The Application of MHD Side Stirring Technology to Aluminium Melting Furnaces for Operational Efficiency Improvement – A Case Study
- Impact of Coil Geometry on Magnetohydrodynamic Flow in Liquid Aluminium and Its Relevance to Inclusion Separation by Electromagnetophoresis
- Mathematical Modeling of the Mold Current and Its Influence on Slag and Ingot Behavior during ESR
- Online Electromagnetic Filtration of Molten Aluminum Using a Multistage Separator System
- Effect of Single-Ruler Electromagnetic Braking (EMBr) Location on Transient Flow in Continuous Casting
- Optimization of an Electromagnetic Technology in ArcelorMittal Gent for Improving Products Quality in Steel Industry
- Control of Slag-Dragging Effects at the Metal–Slag Interface through Electromagnetic Brake in a Slab Mold
- Recent LIMMCAST Results on the Modeling of Steel Casting
- Magnetic Damping of Liquid Steel Flows in Horizontal Single Belt Casting (HSBC)
- A New Electromagnetic Heating Method to Study Spray Cooling
Articles in the same Issue
- Frontmatter
- Preface
- Experimental and Stochastic Modeling of the Globular Microstructure and the Microsegregation Evolution during the Solidification of Magnesium Alloys Cast at Low Superheat via Containerless Melting
- On the Influences of Adjacent Conducting Media and Coil Frequency on the Electromagnetic Field and Flow Characteristics in Solidifying Melts
- Nucleation of Carbon Monoxide Gas Bubbles in Electromagnetically Levitated Molten Iron Drops
- Numerical Analysis of Electromagnetic Levitation Employing Meshless Method Based on Weighted Least Square Method
- Arrays of Rotating Permanent Magnet Dipoles for Stirring and Pumping of Liquid Metals
- Flow Visualization by Means of Contactless Inductive Flow Tomography in the Presence of a Magnetic Brake
- CFD of the MHD Mold Flow by Means of Hybrid LES/RANS Turbulence Modeling
- The Application of MHD Side Stirring Technology to Aluminium Melting Furnaces for Operational Efficiency Improvement – A Case Study
- Impact of Coil Geometry on Magnetohydrodynamic Flow in Liquid Aluminium and Its Relevance to Inclusion Separation by Electromagnetophoresis
- Mathematical Modeling of the Mold Current and Its Influence on Slag and Ingot Behavior during ESR
- Online Electromagnetic Filtration of Molten Aluminum Using a Multistage Separator System
- Effect of Single-Ruler Electromagnetic Braking (EMBr) Location on Transient Flow in Continuous Casting
- Optimization of an Electromagnetic Technology in ArcelorMittal Gent for Improving Products Quality in Steel Industry
- Control of Slag-Dragging Effects at the Metal–Slag Interface through Electromagnetic Brake in a Slab Mold
- Recent LIMMCAST Results on the Modeling of Steel Casting
- Magnetic Damping of Liquid Steel Flows in Horizontal Single Belt Casting (HSBC)
- A New Electromagnetic Heating Method to Study Spray Cooling
