Journal articles: 'Film-boiling process'

1

Maniruzzaman, M., and R. D. Sisson. "Heat transfer coefficients for quenching process simulation." Journal de Physique IV 120 (December 2004): 269–76. http://dx.doi.org/10.1051/jp4:2004120031.

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Quenching heat treatment in a liquid medium is a very complex heat transfer process. Heat extraction from the part surface occurs through several different heat transfer mechanisms in distinct temperature ranges, namely, film boiling, partial film boiling (i.e. transition), nucleate boiling and convection. The maximum heat transfer occurs during the nucleate boiling stage. Experimental study shows that, the effective surface heat transfer coefficient varies more than two orders of magnitude with the temperature during the quenching. For quenching process simulation, accurate prediction of the time-temperature history and microstructure evolution within the part largely depends on the accuracy of the boundary condition supplied. The heat transfer coefficient is the most important boundary condition for process simulation. This study focuses on creating a database of heat transfer coefficients for various liquid quenchant-metallic alloy combinations through experimentation using three different quench probes. This database is a web-based tool for use in quench process simulation. It provides at-a-glance information for quick and easy analysis and sets the stage for a Decision Support System (DSS) and Data Mining for heat-treating process.

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Maniruzzaman, M., and R. D. Sisson. "Heat transfer coefficients for quenching process simulation." Journal de Physique IV 120 (December 2004): 521–28. http://dx.doi.org/10.1051/jp4:2004120060.

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Quenching heat treatment in a liquid medium is a very complex heat transfer process. Heat extraction from the part surface occurs through several different heat transfer mechanisms in distinct temperature ranges, namely, film boiling, partial film boiling (i.e. transition), nucleate boiling and convection. The maximum heat transfer occurs during the nucleate boiling stage. Experimental study shows that, the effective surface heat transfer coefficient varies more than two orders of magnitude with the temperature during the quenching. For quenching process simulation, accurate prediction of the time-temperature history and microstructure evolution within the part largely depends on the accuracy of the boundary condition supplied. The heat transfer coefficient is the most important boundary condition for process simulation. This study focuses on creating a database of heat transfer coefficients for various liquid quenchant-metallic alloy combinations through experimentation using three different quench probes. This database is a web-based tool for use in quench process simulation. It provides at-a-glance information for quick and easy analysis and sets the stage for a Decision Support System (DSS) and Data Mining for heat-treating process.

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Kulju, Timo, Juha Pyykkönen, David C. Martin, Esa Muurinen, Riitta L. Keiski, N. Prabhu, N. Kobasko, and S. W. Dean. "CFD-Simulation of Film Boiling at Steel Cooling Process." Journal of ASTM International 8, no. 8 (2011): 103382. http://dx.doi.org/10.1520/jai103382.

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Clark, L. D., I. Rosindale, K. Davey, S. Hinduja, and P. J. Dooling. "Predicting heat extraction due to boiling in the cooling channels during the pressure die casting process." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 214, no. 3 (March 1, 2000): 465–82. http://dx.doi.org/10.1243/0954406001523119.

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The effect of boiling on the rate of heat extraction by cooling channels employed in pressure die casting dies is investigated. The cooling effect of the channels is simulated using a model that accounts for subcooled nucleate boiling and transitional film boiling as well as forced convection. The boiling model provides a continuous relationship between the rate of heat transfer and temperature, and can be applied to surfaces where forced convection, subcooled nucleate boiling and transitional film boiling are taking place in close proximity. The effects of physical parameters such as flow velocity, degree of subcooling, system pressure and bulk temperature are taken into account. Experimental results are obtained using a rig that simulates the pressure die casting process. The results are compared with the model predictions and are found to show good agreement. Instrumented field tests, on an industrial die casting machine, are also reported. These tests show the beneficial effects of boiling heat transfer in the pressure die casting process, including a 75 per cent increase in the production rate for the test component.

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Kobasko, Nikolai. "INVESTIGATION OF BATCH INTENSIVE QUENCHING PROCESSES WHEN USING HYDRODYNAMIC EMITTERS IN QUENCH TANKS." EUREKA: Physics and Engineering 6 (November 30, 2016): 29–36. http://dx.doi.org/10.21303/2461-4262.2016.00212.

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The paper discusses patented in Ukraine a new intensive quenching IQ–2 technology based on film boiling resonance effect [1]. Namely, the paper discusses improving of the batch intensive quenching (IQ) process known as IQ-2 method by the use of hydrodynamic emitters installed in quench tanks. The hydrodynamic emitters produce oscillating waves in the quench media with the frequency of the film boiling process creating a resonance effect. Two- and three-step IQ-2 processes are considered. Specifics of the heat transfer during the IQ-2 process are presented with focusing on the first stage of quenching where film and nucleate boiling processes are taking place. Examples of production IQ-2 equipment and loads processed are also presented. Application of hydrodynamic emitters in the IQ water tanks in addition to currently used propellers is considered in details. It is shown that the proposed new method can fully eliminate the film boiling process resulting in significant reduction of part distortion during quenching. Further evaluation of the proposed method is needed for its implementation in heat treating practice.

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Park, Jongdoc, Katsuya Fukuda, and Qiusheng Liu. "CHF Phenomena by Photographic Study of Boiling Behavior due to Transient Heat Inputs." Science and Technology of Nuclear Installations 2012 (2012): 1–12. http://dx.doi.org/10.1155/2012/248923.

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The transient boiling heat transfer characteristics in a pool of water and highly wetting liquids such as ethanol and FC-72 due to an exponentially increasing heat input of various rates were investigated using the 1.0 mm diameter experimental heater shaped in a horizontal cylinder for wide ranges of pressure and subcooling. The trend of critical heat flux (CHF) values in relation to the periods was divided into three groups. The CHF belonging to the 1st group with a longer period occurs with a fully developed nucleate boiling (FDNB) heat transfer process. For the 2nd group with shorter periods, the direct transition to film boiling from non boiling occurs as an explosive boiling. The direct boiling transition at the CHF from non-boiling regime to film boiling occurred without a heat flux increase. It was confirmed that the initial boiling behavior is significantly affected by the property and the wettability of the liquid. The photographic observations on the vapor bubble behavior during transitions to film boiling were performed using a high-speed video camera system.

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PANZARELLA, CHARLES H., STEPHEN H. DAVIS, and S. GEORGE BANKOFF. "Nonlinear dynamics in horizontal film boiling." Journal of Fluid Mechanics 402 (January 10, 2000): 163–94. http://dx.doi.org/10.1017/s0022112099006801.

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This paper uses thin-film asymptotics to show how a thin vapour layer can support a liquid which is heated from below and cooled from above, a process known as horizontal film boiling. This approach leads to a single, strongly-nonlinear evolution equation which incorporates buoyancy, capillary and evaporative effects. The stability of the vapour layer is analysed using a variety of methods for both saturated and subcooled film boiling. In subcooled film boiling, there is a stationary solution, a constant-thickness vapour film, which is determined by a simple heat-conduction balance. This is Rayleigh–Taylor unstable because the heavier liquid is above the vapour, but the instability is completely suppressed for sufficient subcooling. A bifurcation analysis determines a supercritical branch of stable, spatially-periodic solutions when the basic state is no longer stable. Numerical branch tracing extends this into the strongly-nonlinear regime, revealing a hysteresis loop and a secondary bifurcation to a branch of travelling waves which are stable under certain conditions. There are no stationary solutions in saturated film boiling, but the initial development of vapour bubbles is determined by directly solving the time-dependent evolution equation. This yields important information about the transient heat transfer during bubble development.

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Kobasko, Nikolai, Anatolii Moskalenko, and Volodymyr Dobryvechir. "RESEARCH ON USE OF LOW CONCENTRATION INVERSE SOLUBILITY POLYMERS IN WATER FOR HARDENING MACHINE COMPONENTS AND TOOLS." EUREKA: Physics and Engineering 2 (March 30, 2018): 63–71. http://dx.doi.org/10.21303/2461-4262.2018.00582.

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There is an optimal water concentration of inverse solubility polymers ( 1 %) where in many cases film boiling is absent. Based on accurate experimental data of French and data of authors, it was shown that during quenching from 875 oC in cold water solutions of optimal concentration film boiling is completely absent for those steel parts initial heat flux densities of which are below critical value. It is established that initial heat flux density decreases with increase sizes of tested samples. Initial process of quenching (formation of boundary boiling layer), which makes further history of cooling, is not investigated deeply and widely yet enough. When film boiling is absent, mathematical model includes only transient nucleate boiling process and convection. In this case, cooling time within the transient nucleate boiling process can be calculated using average effective Kondratjev numbers Kn. They were evaluated for inverse solubility polymers depending on their concentration and sizes of tested samples. As a result, an improved technology of hardening large gears and bearing rings is proposed by authors. Its essence consists in interruption of accelerated cooling or turning off agitation of quenchant when dissolving of surface polymeric layer starts. Examples of performing improved technology are provided by authors. Developments can be used by engineers to switch from carburized large gears quenched in oil to gears made of optimal hardenability steel and quenched in water solutions of optimal concentration.

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Ahn, Hee Seok, Nipun Sinha, Mei Zhang, Debjyoti Banerjee, Shaoli Fang, and Ray H. Baughman. "Pool Boiling Experiments on Multiwalled Carbon Nanotube (MWCNT) Forests." Journal of Heat Transfer 128, no. 12 (May 29, 2006): 1335–42. http://dx.doi.org/10.1115/1.2349511.

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In this study, two silicon wafer substrates were coated with vertically aligned multiwalled carbon nanotubes (MWCNT) “forests” and were used for pool boiling studies. The MWCNT forests (9 and 25μm in height) were synthesized on the silicon wafer substrates using chemical vapor deposition (CVD) process. The substrates were clamped on a cylindrical copper block with embedded cartridge heaters. The heat flux was measured using sheathed K-type thermocouples, which were placed inside the cylindrical copper block. Pool boiling experiments using refrigerant PF-5060 as the working liquid were conducted to obtain the pool “boiling curve.” The experiments were conducted in nucleate and film boiling regimes to investigate the effect of MWCNT height on pool boiling performance. Reference (control) experiments were also performed with an atomically smooth bare silicon wafer (without MWCNT coating). The results show that the MWCNT forests enhanced critical heat flux (CHF) by 25-28% compared to control experiments. For the film boiling regime, Type-B MWCNT (25μm in height) yields 57% higher heat flux at Leidenfrost point (film boiling regime) compared to control experiments. However, for the Type-A MWCNT (9μm in height) the film boiling heat flux values are nearly identical to the values obtained for the control experiments performed on bare silicon.

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Liao, Ming-Jun, and Li-Qiang Duan. "Effect of the Hybrid Hydrophobic-Hydrophilic Nanostructured Surface on Explosive Boiling." Coatings 11, no. 2 (February 11, 2021): 212. http://dx.doi.org/10.3390/coatings11020212.

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The influence of different wettability on explosive boiling exhibits a significant distinction, where the hydrophobic surface is beneficial for bubble nucleation and the hydrophilic surface enhances the critical heat flux. Therefore, to receive a more suitable surface for the explosive boiling, in this paper a hybrid hydrophobic–hydrophilic nanostructured surface was built by the method of molecular dynamics simulation. The onset temperatures of explosive boiling with various coating thickness, pillar width, and film thicknesses were investigated. The simulation results show that the hybrid nanostructure can decrease the onset temperature compared to the pure hydrophilic surface. It is attributed to the effect of hydrophobic coating, which promotes the formation of bubbles and causes a quicker liquid film break. Furthermore, with the increase of the hydrophobic coating thickness, the onset temperature of explosive boiling decreases. This is because the process of heat transfer between the liquid film and the hybrid nanostructured surface is inevitably enhanced. In addition, the onset temperature of explosive boiling on the hybrid wetting surface decreases with the increase of pillar width and liquid film thickness.

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Genbach, Alexander, Karlygash Оlzhabaeva, and Iliya Iliev. "Boiling process in oil coolers on porous elements." Thermal Science 20, no. 5 (2016): 1777–89. http://dx.doi.org/10.2298/tsci150602166g.

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Holography and high-speed filming were used to reveal movements and deformations of the capillary and porous material, allowing to calculate thermo-hydraulic characteristics of boiling liquid in the porous structures. These porous structures work at the joint action of capillary and mass forces, which are generalised in the form of dependences used in the calculation for oil coolers in thermal power plants (TPP). Furthermore, the mechanism of the boiling process in porous structures in the field of mass forces is explained. The development process of water steam formation in the mesh porous structures working at joint action of gravitational and capillary forces is investigated. Certain regularities pertained to the internal characteristics of boiling in cells of porous structure are revealed, by means of a holographic interferometry and high-speed filming. Formulas for calculation of specific thermal streams through thermo-hydraulic characteristics of water steam formation in mesh structures are obtained, in relation to heat engineering of thermal power plants. This is the first calculation of heat flow through the thermal-hydraulic characteristics of the boiling process in a reticulated porous structure obtained by a photo film and holographic observations.

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Besnard, C., A. Allemand, P. David, and L. Maillé. "Synthesis of hexacelsian barium aluminosilicate by film boiling chemical vapour process." Journal of the European Ceramic Society 40, no. 9 (August 2020): 3494–97. http://dx.doi.org/10.1016/j.jeurceramsoc.2020.02.021.

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GE, YANG, and L. S. FAN. "Droplet–particle collision mechanics with film-boiling evaporation." Journal of Fluid Mechanics 573 (February 2007): 311–37. http://dx.doi.org/10.1017/s0022112006003922.

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A three-dimensional numerical model is developed to simulate the process of collision between an evaporative droplet and a high-temperature particle. This phenomenon is of direct relevance to many engineering process operations, such as fluid catalytic cracking (FCC), polyethylene synthesis, and electronic materials coating. In this study, the level-set method and the immersed-boundary method are combined to describe the droplet–particle contact dynamics in a fixed Eulerian grid. The droplet deformation is captured by one level-set function while the solid–fluid boundary condition is imposed on the particle surface through the immersed-boundary method involving another level-set function. A two-dimensional vapour-layer model is developed to simulate the vapour flow dynamics. Equations for the heat transfer characteristics are formulated for each of the solid, liquid and gas phases. The incompressible flow-governing equations are solved using the finite-volume method with the ALE (arbitrary Lagrangian Eulerian) technique. The simulation results are validated through comparisons with experimental data obtained from the new experimental set-up designed in this study. An important feature of the droplet impacting on a particle with film boiling is that the droplet undergoes a spreading, recoiling and rebounding process, which is reproduced by the numerical simulation based on the model. Details of the collision such as spread factor, contact time and temperature distribution are provided. Simulations are also conducted to examine the effects of the particle size and the collision velocity. Although the value for the maximum spread factor is larger for a higher impact velocity and for a smaller particle, the contact time is independent of the impact velocity and particle size. Both the normal collision and the oblique collision are considered in this study.

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Kobasko, Nikolai Mykola. "Intense Quench Process in Slow Agitated Water Salt and Polymer Solutions." European Journal of Applied Physics 3, no. 3 (May 21, 2021): 6–12. http://dx.doi.org/10.24018/ejphysics.2021.3.3.76.

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In the paper it is shown that quenching in slow agitated water salt solution of optimal concentration and in low concentration of inverse solubility polymers is intensive quenching creating maximal temperature gradients at the beginning of cooling. The evidence to support such idea were collected by analyzing quenching process in liquid media where any film boiling process was completely absent. In this case, surface temperature at the beginning of cooling drops closely to saturations temperature of a liquid within the interval 1–2 seconds, independently on nature of water solution, and then during transient nucleate boiling process maintains at the level of boiling point of a liquid which is often called self–regulated thermal process. The computer modeling of such cooling processes provided Kondrat’ev numbered Kn which are strongly linear function of time. At the beginning of cooling Kondrat’ev number is almost equal to 1 while average Kondrat’ev number Kn≥0.8. According to US Patent, intensive quenching starts when Kn=0.8. Based on achieved results, it is possible to perform intensive quenching in slow agitated of low concentration water salt and polymer solutions, usually initiated by hydrodynamic emitters. Along with liquid agitation, emitters generate resonance wave effect which destroys film boiling processes making cooling very uniform and intensive. The proposed IQ process works perfectly when martensite starts temperature Ms>Ts. If saturation temperature Ts≥Ms, intensive austempering process via cold liquids can be successfully performed to replace slow cooling of molten salts and alkalis by intensive quenching in liquid media.

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Caron, Etienne J. F. R., and Mary A. Wells. "Effect of Advanced Cooling Front (ACF) Phenomena on Film Boiling and Transition Boiling Regimes in the Secondary Cooling Zone during the Direct-Chill Casting of Aluminium Alloys." Materials Science Forum 519-521 (July 2006): 1687–92. http://dx.doi.org/10.4028/www.scientific.net/msf.519-521.1687.

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Accurate knowledge of the boundary conditions is essential when modeling the Direct-Chill (DC) casting process. Determining the surface heat flux in the secondary cooling zone, where the greater part of the heat removal takes place, is therefore of critical importance. Boiling water heat transfer phenomena are quantified with boiling curves which express the heat flux density as a function of the surface temperature. Compilations of boiling curves for the DC casting of aluminum alloys present a good agreement at low surface temperatures but a very poor agreement at higher surface temperatures, in the transition boiling and film boiling modes. Secondary cooling was simulated by spraying instrumented samples with jets of cooling water. Quenching tests were conducted first with a stationary sample, and then with a sample moving at a constant “casting speed” in order to better simulate the DC casting process. The ejection of the water film in quenching tests with a stationary sample and the relative motion between the sample and the water jets both lead to an Advanced Cooling Front (ACF) effect, in which cooling occurs through axial conduction within the sample rather than through boiling water heat transfer at the surface. The heat flux density and surface temperature were evaluated using the measured thermal history data in conjunction with a two-dimensional inverse heat conduction (IHC) model. The IHC model developed at the University of British Columbia was able to take into account the advanced cooling front effect. The effect of various parameters (initial sample temperature, casting speed, water flow rate) on the rate of heat removal in the film boiling and transition boiling regimes was investigated.

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Kobasko, Nikolai, Anatolii Moskalenko, Petro Lohvynenko, Larisa Karsim, and Sergii Riabov. "AN EFFECT OF PIB ADDITIVES TO MINERAL OIL RESULTING IN ELIMINATION OF FILM BOILING DURING STEEL PARTS QUENCHING." EUREKA: Physics and Engineering 3 (May 31, 2016): 17–24. http://dx.doi.org/10.21303/2461-4262.2016.00076.

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To control the process of film boiling during quenching in oils, quench oil makers as a rule manipulate physical properties such as a surface tension and viscosity. However, there is much experimental data showing that special additives can eliminate film boiling in oils without changing their physical properties and which is counterintuitive. Authors explain such phenomenon by showing that the addition of a special additive, for example PIB (polyisobutylene polymer), will create an insulating layer on the surface of steel parts during quenching in oils that will eliminate film boiling without affecting physical properties of the oil. Insulating layer decreases initial heat flux density which becomes less than critical one and of the oil will not begin film boiling during quenching with the PIB additive. Authors believe that such approach will allow engineers to solve effectively the problem of part distortion after quenching. The new oil quenchant containing special additive PIB is patented in Ukraine and is manufactured by Barkor Ltd for needs of the heat treating industry.

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Joung, Young Soo, and Cullen R. Buie. "Hybrid Electrophoretic Deposition with Anodization Process for Superhydrophilic Surfaces to Enhance Critical Heat Flux." Key Engineering Materials 507 (March 2012): 9–13. http://dx.doi.org/10.4028/www.scientific.net/kem.507.9.

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Superhydrophilic surfaces with hydrophobic layers were successfully produced in order to enhance critical heat flux (CHF) and reduce boiling inception temperatures (BIT). The novel surfaces were fabricated by a hybrid electrophoretic deposition (EPD) method coupled with a break down anodization (BDA) process. With the BDA process, microporous superhydrophilic surfaces were created on titanium substrates. Subsequently, nanoporous hydrophobic layers were deposited with EPD on the superhydrophilic surfaces. The hydrophobic layers provide numerous nucleation sites, lowering BIT while the superhydrophilic layers prevent film boiling, resulting in increased CHF. The resulting surfaces exhibit higher CHF with lower BIT than untreated titanium surfaces .

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Evans, D., S. W. Webb, and J. C. Chen. "Axially Varying Vapor Superheats in Convective Film Boiling." Journal of Heat Transfer 107, no. 3 (August 1, 1985): 663–69. http://dx.doi.org/10.1115/1.3247475.

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Axially varying vapor superheats in convective film boiling have been measured for water flowing in a vertical tube at low to moderate pressures and mass flow rates. Using a slow “reflood” process, measurements of wall temperature and nonequilibrium vapor temperature were obtained as functions of distance from the quench front. With the low quench front velocity, the time required to progapate the front a few millimeters corresponds to many fluid residence times, and the thermal hydraulic data thus obtained are quasi-steady state. These experimental results indicate a zone near the quench front where the vapor generation rate is relatively high, followed by a far zone where the generation rate drops off to a relatively low magnitude. The data obtained agree with the very limited previously reported steady-state data. Comparison with existing heat transfer models shows the models give poor predictions of vapor superheats but reasonable predictions of wall heat fluxes.

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Okuno, H., M. Trinquecoste, A. Derré, M. Monthioux, and P. Delhaès. "Catalytic effects on carbon/carbon composites fabricated by a film boiling chemical vapor infiltration process." Journal of Materials Research 17, no. 8 (August 2002): 1904–13. http://dx.doi.org/10.1557/jmr.2002.0283.

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Chemical vapor infiltration (CVI) has been widely studied under several conditions to obtain C/C composites. A “film boiling technique” (so-called Kalamazoo), by the use of liquid precursor, based on thermal gradient CVI has been recently developed as one of the very effective techniques to increase the carbon yield and the densification rate. A small cold wall type laboratory reactor has been realized to analyze the kinetics of reactions and the deposited pyrocarbon matrix. In this study, ferrocene, as the source of catalyst, is mixed to the liquid precursor to induce a catalytic effect on the film boiling technique since the transition metals are known to increase the carbon deposition rate. In addition to an important increase of the densification rate, it is revealed that the deposition mechanism and microtextures are completely modified by the presence of catalyst, with the presence of multiwall nanotubes within the matrix. A model has been adapted from Allendorff and Hunt's work to interpret this peculiar deposition mechanism.

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MURATA, Kyouhei, and Sigefumi NISHIO. "Mechanism of Film-Boiling Onset in Transient Cooling Process with Highly Subcooled Water and Unstable Boiling-Cooling Phenomena." Tetsu-to-Hagane 79, no. 1 (1993): 55–61. http://dx.doi.org/10.2355/tetsutohagane1955.79.1_55.

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Caron, Etienne, and Mary A. Wells. "Film Boiling and Water Film Ejection in the Secondary Cooling Zone of the Direct-Chill Casting Process." Metallurgical and Materials Transactions B 43, no. 1 (September 23, 2011): 155–62. http://dx.doi.org/10.1007/s11663-011-9579-1.

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Yamauchi, Hiroshi, Michimasa Uda, and Haruhiko Soeda. "Development of low-cost C/C, related technology using a film-boiling process." TANSO 2018, no. 284 (September 1, 2018): 143–50. http://dx.doi.org/10.7209/tanso.2018.143.

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Yamauchi, Hiroshi, Michimasa Uda, and Haruhiko Soeda. "Development of low-cost C/C, related technology using a film-boiling process." Carbon 175 (April 2021): 609. http://dx.doi.org/10.1016/j.carbon.2021.01.061.

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Lee, Jun Ho, Ho Jun Park, Chae Eun Im, Jong Gyeom Kim, Dong Eun Gu, and Suk Jun Kim. "Effect of Co-Solvent Percentages on the Exfoliation Rate of NiTe2 Thin Film for Transparent Electrodes." Korean Journal of Metals and Materials 59, no. 7 (July 5, 2021): 481–90. http://dx.doi.org/10.3365/kjmm.2021.59.7.481.

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We attempted to maximize the transmittance of 2D NiTe2 thin film using the liquid-phase exfoliation (LPE) process to confirm the applicability of NiTe2 as a transparent electrode. The LPE process, using a co-solvent of organic solvent and water, is a stable and efficient method of increasing transmittance at low cost. In this report, the effect of 12 different co-solvents, mixtures of acetone, ethanol, isopropyl alcohol, and water, on exfoliation rate was studied. NiTe2 thin film with a thickness of 6.3 nm prepared by sputtering, and exhibited a highest transmittance of 68% and a lowest resistivity of 291 μΩ·cm after 12 hrs sonication in ethanol/water co-solvent (ethanol : water = 60 : 40 vol. %). Three physical properties, polarization and dispersion ratio (p/d ratio), boiling point, and water contents, were compared to determine which property was the main control factor for the LPE process. Unlike previous LPE processes for powders of 2D materials, it was revealed that the improvement in the transmittance of the NiTe2 thin film was more strongly dependent on both of vol.% of water and boiling point of the solvents. This was because the transmittance improved after removing the NiTe2 thin film from the substrate, rather than layer by layer exfoliation. We believe that NiTe2 thin film prepared by sputtering followed by exfoliation process can be one of the potential candidates for transparent electrode.

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Dawley, J. T., P. G. Clem, M. P. Siegal, D. R. Tallant, and D. L. Overmyer. "Improving sol-gel Yba2Cu3O7−δ film morphology using high-boiling-point solvents." Journal of Materials Research 17, no. 8 (August 2002): 1900–1903. http://dx.doi.org/10.1557/jmr.2002.0282.

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The effect of high-boiling-point solvent addition on the morphology of low-p(O2) processed, sol-gel YBa2Cu3O7−δ (YBCO) films is discussed. Proper selection and addition of a high-boiling-point solvent prevents film roughening during precursor pyrolysis, while permitting at least a tenfold reduction in pyrolysis time compared to standard film processing in air or O2. Use of such solvents appears to increase film plasticity, avoiding elastic compressive stress related buckling. High-quality YBCO films on 〈100〉 LaAlO3 with a critical current density (Jc) ∼ 3–4 MA/cm2 at 77 K, are routinely crystallized with this new sol-gel process. Diethanolamine-based, sol-gel YBCO films deposited on sol-gel SrTiO3-buffered 〈100〉 Ni have Jc(77 K) > 1 MA/cm2, demonstrating a route toward all-sol-gel superconducting wires.

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Сапожников, С. З., В. Ю. Митяков, А. В. Митяков, and В. В. Субботина. "Экспериментальное исследование пленочного кипения недогретой воды методом градиентной теплометрии." Письма в журнал технической физики 45, no. 6 (2019): 10. http://dx.doi.org/10.21883/pjtf.2019.06.47490.17594.

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AbstractThe process of subcooled water boiling is qualitatively described based on data obtained using gradient heat flux measurement. The proposed method was used for the first time for measuring the heat flux per unit area during film boiling that takes place on the endface of a cylinder submerged in subcooled water. Based on these results, the time distribution of the heat flux per unit area are constructed and the relationship between the heat flux per unit area and heat-transfer coefficient is estimated.

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Chen, Jianye, Ruirui Zeng, Xiaobin Zhang, Limin Qiu, and Junlong Xie. "Numerical modeling of flow film boiling in cryogenic chilldown process using the AIAD framework." International Journal of Heat and Mass Transfer 124 (September 2018): 269–78. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2018.03.087.

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Sun, Chen-li, and Van P. Carey. "Effects of Gap Geometry and Gravity on Boiling Around a Constrained Bubble in 2-Propanol/Water Mixtures." Journal of Heat Transfer 129, no. 2 (May 15, 2006): 114–23. http://dx.doi.org/10.1115/1.2402178.

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In this study, boiling experiments were conducted with 2-propanol/water mixtures in confined gap geometry under various levels of gravity. The temperature field created within the parallel plate gap resulted in evaporation over the portion of the vapor-liquid interface of the bubble near the heated surface, and condensation near the cold surface. Full boiling curves were obtained and two boiling regimes—nucleate boiling and pseudofilm boiling—and the transition condition, the critical heat flux (CHF), were identified. The observations indicated that the presence of the gap geometry pushed the nucleate boiling regime to a lower superheated temperature range, resulting in correspondingly lower heat flux. With further increases of wall superheat, the vapor generated by the boiling process was trapped in the gap to blanket the heated surface. This caused premature occurrence of CHF conditions and deterioration of heat transfer in the pseudo-film boiling regime. The influence of the confined space was particularly significant when greater Marangoni forces were present under reduced gravity conditions. The CHF value of x (molar fraction)=0.025, which corresponded to weaker Marangoni forces, was found to be greater than that of x=0.015 with a 6.4mm gap.

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Avramenko, А., M. Kovetskaya, A. Tyrinov, and Yu Kovetska. "Characteristics of supercritical heat transfer during filmboiling of nanofluids on a vertical heated wall." Nuclear and Radiation Safety, no. 4(80) (December 3, 2018): 29–35. http://dx.doi.org/10.32918/nrs.2018.4(80).05.

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Nanofluid using for intensification of heat transfer during boiling are analyzed. The using boiling nanofluids for cooling high-temperature surfaces allows significantly intensify heat transfer process by increasing the heat transfer coefficient of a nanofluid in comparison with a pure liquid. The properties of nanoparticles, their concentration in the liquid, the underheating of the liquid to the saturation temperature have significant effect on the rate of heat transfer during boiling of the nanofluid. Increasing critical heat flux during boiling of nanofluids is associated with the formation of deposition layer of nanoparticles on heated surface, which contributes changing in the microcharacteristics of heat exchange surface. An increase in the critical heat flux during boiling of nanofluids is associated with the formation of a layer of deposition of nanoparticles on the surface, which contributes to a change in the microcharacteristics of the heat transfer of the surface. Mathematical model and results of calculation of film boiling characteristics of nanofluid on vertical heated wall are presented. It is shown that the greatest influence on the processes of heat and mass transfer during film boiling of the nanofluid is exerted by wall overheating, the ratio of temperature and Brownian diffusion and the concentration of nanoparticles in the liquid. The mathematical model does not take into account the effect changing structure of the heated surface on heat transfer processes but it allows to evaluate the effect of various thermophysical parameters on intensity of deposition of nanoparticles on heated wall. The obtained results allow to evaluate the effect of nanofluid physical properties on heat and mass transfer at cooling of high-temperature surfaces. The using nanofluids as cooling liquids for heat transfer equipment in the regime of supercritical heat transfer promotes an increase in heat transfer and accelerates the cooling process of high-temperature surfaces. Because of low thermal conductivity of vapor in comparison with the thermal conductivity of the liquid, an increase in the concentration of nanoparticles in the vapor contributes to greater growth in heat transfer in the case of supercritical heat transfer.

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Senda, J., and H. G. Fujimoto. "Multidimensional Modeling of Impinging Sprays on the Wall in Diesel Engines." Applied Mechanics Reviews 52, no. 4 (April 1, 1999): 119–38. http://dx.doi.org/10.1115/1.3098930.

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This article summarizes model analysis of the dispersion process of a Diesel spray on the wall surface in order to simulate the spray-wall interaction process in Diesel engines. The mixture formation process near the wall of the piston cavity affects the combustion process and the hydrocarbon or soot formation process through the quenching of the mixture and flame at the wall surface. In particular, mixture burning occurs mainly near the cavity wall through the whole combustion period in the case of high pressure fuel injection. In this article, representative modeling approaches on spray-wall interaction process including the film flow formation are summarized briefly. Then, our models of spray impingement for low/high-temperature models including the process of fuel film formation, film breakup, wall-drop/film heat transfer, and droplet breakup owing to the solid-liquid interface boiling are introduced with the comparison of experimental results. This review article includes 83 references.

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31

Букин, Владимир Григорьевич, Vladimir Grigorievich Bukin, Александр Букин, and Aleksandr Bukin. "Studying heat transfer in freon-oil mixture boiling in evaporator tubes in ship refrigerating units." Vestnik of Astrakhan State Technical University. Series: Marine engineering and technologies 2019, no. 4 (November 15, 2019): 82–88. http://dx.doi.org/10.24143/2073-1574-2019-4-82-88.

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The paper describes small-capacity irrigation evaporators that improve the performance of a refrigeration unit, as they exclude the release of liquid freon into the compressor suction pipe under sharp increasing of heat load or during ship rolling. The relevance of studying heat transfer at freons boiling in a moving film has been proved. The results and analysis of experimental data on average heat transfer coefficients are presented. The graph shows the dependence of the average heat transfer coefficients on the heat flux density at various irrigation densities. There are presented the results of special experiments determining the effect of irrigation density on heat transfer. It has been stated that the effect of pressure or saturation temperature in the modes of evaporation and developed boiling manifests itself in different ways. With developed boiling, the beam pitch does not have a significant effect on heat transfer. The experiments were carried out on two stands: small-row and multi-row. The pipes were heated with an internal electric heater. It has been inferred that heat transfer in the film is more intense than in volume, therefore, smooth steel pipes can be used in irrigation evaporators instead of finned copper tubes, which are used in flooded devices. The boiling process in a film can be described by equations valid for a large volume, taking into account quantitative differences. The values of a constant coefficient and the criteria exponents are given; the similarity equation for the regime of developed bubble boiling of freons is derived. The calculated dependencies can be applied in evaluating the operation of irrigation evaporators of ship refrigeration units.

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32

Nosoko, T., and Y. H. Mori. "Vaporization of Drops of a Denser, Volatile Liquid Dropped Onto a Surface of Another Liquid." Journal of Heat Transfer 107, no. 2 (May 1, 1985): 384–91. http://dx.doi.org/10.1115/1.3247426.

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Experiments were performed with single R 113 (C2Cl3F3) drops dropped onto the surface of immiscible ethylene glycol or water, or miscible n-tridecane in contact with the common vapors of the two liquids. Five different vaporization modes were distinguished in the immiscible systems: film boiling on the surface, film boiling in the bulk (only in R 113/ethylene glycol system), and three other modes in which the two liquids make direct contact. The latter three were replaced, in the miscible system, by an immediate dissolving of drops into the medium. The details of dynamic process in each mode have been revealed with the aid of high-speed cinephotography. Operational conditions required for the occurrence of respective modes and heat transfer characteristics in those modes have also been discussed.

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33

Roques, J. F., V. Dupont, and J. R. Thome. "Falling Film Transitions on Plain and Enhanced Tubes." Journal of Heat Transfer 124, no. 3 (May 10, 2002): 491–99. http://dx.doi.org/10.1115/1.1458017.

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In falling film heat transfer on horizontal tube bundles, liquid flow from tube to tube occurs as a falling jet that can take on different flow modes. At low flow rates, the liquid film falls as discrete droplets. At higher flow rates, these droplets form discretely spaced liquid columns. At still higher flow rates, the film falls as a continuous sheet of liquid. Predicting the flow transitions between these flow modes is an essential step in determining the heat transfer coefficient for the particular flow mode, whether for a single phase process or for falling film condensation or evaporation. Previous studies have centered mostly on falling films on plain tube arrays. The objective of the present study is to extend the investigation to tubes with enhanced surfaces: a low finned tube, an enhanced boiling tube and an enhanced condensation tube. The effect of tube spacing on flow transition has also been investigated. The test fluids were water, glycol and a glycol-water mixture. The adiabatic experimental results show that the flow mode transition thresholds for the enhanced boiling tube are very similar to those of the plain tube while the fin structure of the other two enhanced tubes can significantly shift their transition thresholds.

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Chen, Jianye, Ruirui Zeng, Hong Chen, and Junlong Xie. "Effects of wall superheat and mass flux on flow film boiling in cryogenic chilldown process." AIP Advances 10, no. 1 (January 1, 2020): 015123. http://dx.doi.org/10.1063/1.5135643.

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35

Mandrusiak, G. D., and V. P. Carey. "Convective Boiling in Vertical Channels With Different Offset Strip Fin Geometries." Journal of Heat Transfer 111, no. 1 (February 1, 1989): 156–65. http://dx.doi.org/10.1115/1.3250638.

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Newly obtained local heat transfer data are presented for flow boiling of liquids in two partially heated vertical channels with different offset strip fin geometries operating at low to moderate wall superheat levels. Experiments were conducted in special test sections that permitted direct visual observation of the boiling process while simultaneously measuring the heat transfer coefficient along the channel. Data for which nucleate boiling appeared to be completely suppressed were analyzed together with similar results for other offset fin geometries to assess the effects of channel geometry variations on the two-phase heat transfer coefficient during annular film-flow evaporation. For all geometries considered, the data for annular film-flow evaporation were found to correlate well in terms of modified versions of the F and Martinelli parameters used by Bennett and Chen (1980) to correlate similar data for round tubes. For fin matrices of similar size and configuration, the forced convective component of the two-phase heat transfer coefficient was found to be well represented by a single F-parameter correlation curve. However, F-factor correlations for matrices having significant differences in fin and channel dimensions were found to differ substantially. An approximate superposition method for including the contribution of nucleate boiling to the two-phase heat transfer coefficient at low to moderate wall superheat levels is also proposed.

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36

Zhang, Lei, Wen Bo Bi, and Ru Bo Zhang. "An Approximate Solution of Energy Partition in Grind-Hardening Process." Advanced Materials Research 135 (October 2010): 298–302. http://dx.doi.org/10.4028/www.scientific.net/amr.135.298.

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In order to estimate the energy partition within the workpiece, an integral approximation solution of energy partition is found in the grind-hardening process. Heat transfer models of the abrasive grain, workpiece, chips and fluid were analyzed by using the integral approximation method. The present model can calculate the energy partition with and without film boiling in the grinding zone. The temperature underneath the surface of the workpiece was measured using semi--natural thermocouple method. The workpiece background temperature calculated by the present model agreed very well with the experimental results. Energy partition model can be used to calculate the grinding temperature for controlling thermal damage and predicting the harden layer depth in grinding.

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37

Kobasko, Nikolai. "IMPROVEMENT OF IQ - 3 PROCESSES TO ELIMINATE CRACK FORMATION, DECREASE DISTORTION, AND MAXIMIZE MATERIAL STRENGTH, AND DUCTILITY." EUREKA: Physics and Engineering 4 (July 29, 2016): 3–10. http://dx.doi.org/10.21303/2461-4262.2016.000122.

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The paper presents an overview and significant improvement of one of the intensive quenching processes (namely, the IQ-3 process). The IQ-3 process is an interrupted quench method that is usually implemented in high-velocity single-part quenching IQ units. The IQ-3 process is often called a direct convection quenching since, due to a very high water flow rates through the quench chamber, both the film boiling process and the nucleate boiling process are eliminated completely, and convention process starts immediately after beginning of the quench. Different criteria of the IQ-3 process interruption are considered. Normally, the IQ-3 process is interrupted at a time when current surface compressive stresses are at their maximum value. After a conventional IQ-3 process, there is a mixed structure in the part core. The paper focuses on the IQ-3 method that provides a bainitic structure in the part core. A method for calculation of a required water flow rate for high-velocity IQ systems for providing the bainitic part core structure is discussed.

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38

Li, Chen, and G. P. Peterson. "Parametric Study of Pool Boiling on Horizontal Highly Conductive Microporous Coated Surfaces." Journal of Heat Transfer 129, no. 11 (April 10, 2007): 1465–75. http://dx.doi.org/10.1115/1.2759969.

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To better understand the mechanisms that govern the behavior of pool boiling on horizontal highly conductive microporous coated surfaces, a series of experimental investigations were designed to systematically examine the effects of the geometric dimensions (i.e., coating thickness, volumetric porosity, and pore size, as well as the surface conditions of the porous coatings) on the pool-boiling performance and characteristics. The study was conducted using saturated distilled water at atmospheric pressure (101kPa) and porous surfaces fabricated from sintered isotropic copper wire screens. For nucleate boiling on the microporous coated surfaces, two vapor ventilation modes were observed to exist: (i) upward and (ii) mainly from sideways leakage to the unsealed sides and partially from the center of porous surfaces. The ratio of the heater size to the coating thickness, the friction factor of the two-phase flow to single-phase flow inside the porous coatings, as well as the input heat flux all govern the vapor ventilation mode that occurs. In this investigation, the ratio of heater size to coating thickness varies from 3.5 to 38 in order to identify the effect of heater size on the boiling characteristics. The experimental results indicate that the boiling performance and characteristics are also strongly dependent on the volumetric porosity and mesh size, as well as the surface conditions when the heater size is given. Descriptions and discussion of the typical boiling characteristics; the progressive boiling process, from pool nucleate boiling to film boiling; and the boiling performance curves on conductive microporous coated surfaces are all systematically presented.

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39

Wang, Ji-ping, Jun-min Qian, Guan-jun Qiao, and Zhi-hao Jin. "Improvement of film boiling chemical vapor infiltration process for fabrication of large size C/C composite." Materials Letters 60, no. 9-10 (May 2006): 1269–72. http://dx.doi.org/10.1016/j.matlet.2005.11.012.

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40

Vignoles, Gérard L., Jean-Marc Goyhénèche, Patrick Sébastian, Jean-Rodolphe Puiggali, Jean-François Lines, Jean Lachaud, Pierre Delhaès, and Michel Trinquecoste. "The film-boiling densification process for C/C composite fabrication: From local scale to overall optimization." Chemical Engineering Science 61, no. 17 (September 2006): 5636–53. http://dx.doi.org/10.1016/j.ces.2006.04.025.

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41

Schmidt, Anna, Matthias Bonarens, Ilia V. Roisman, Kaushal Nishad, Amsini Sadiki, Andreas Dreizler, Jeanette Hussong, and Steven Wagner. "Experimental Investigation of AdBlue Film Formation in a Generic SCR Test Bench and Numerical Analysis Using LES." Applied Sciences 11, no. 15 (July 27, 2021): 6907. http://dx.doi.org/10.3390/app11156907.

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In this work, an experimental investigation of AdBlue film formation in a generic selective catalytic reduction (SCR) exhaust gas test bench is presented. AdBlue is injected into a generic SCR test bench resulting in liquid film formation on the lower wall of the channel. The thickness of this liquid film is measured using a film thickness sensor based on absorption spectroscopy. Simultaneously, the wall temperature at the measurement point is monitored, which allows for examining correlations between the evolution of the film thickness and the temperature of the wetted wall. The velocity of the airflow in the channel and the initial wall temperature are varied in the experiments. Correspondingly, the measurements are performed during different thermodynamic regimes, including liquid film deposition and boiling. Repeated measurements have also shown that the film thicknesses are reproducible with a standard deviation of 3.4 %. LES-based numerical simulations are compared to the experimental results of the film thickness during the early injection stage. Finally, a numerical analysis is performed to analyze the AdBlue droplet impingement and subsequent film-formation dynamics.

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42

Merte, H., and H. S. Lee. "Quasi-Homogeneous Nucleation in Microgravity at Low Heat Flux: Experiments and Theory." Journal of Heat Transfer 119, no. 2 (May 1, 1997): 305–12. http://dx.doi.org/10.1115/1.2824224.

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Experiments were conducted in the microgravity of space in which a pool of liquid (R-113), initially at a defined pressure and temperature, was subjected to a step imposed heat flux from a semitransparent thin-film heater forming part of one wall of the container such that boiling is initiated and maintained for a defined period of time at a constant pressure level. Measurements of the transient heater surface and fluid temperatures near the surface were made, noting in particular the conditions at the onset of boiling, along with motion photography of the boiling process in two simultaneous views, from beneath the heating surface and from the side. A total of nine tests were conducted at three levels of heat flux and three levels of subcooling. They were repeated under essentially identical circumstances in each of three space experiments. The absence of buoyancy resulted in the onset of boiling at low heat flux levels, with what is defined as quasi-homogeneous nucleation taking place. The influence of these low levels of heat flux and the pressure effect used to produce the bulk liquid subcooling are accounted for by a modification of classical homogeneous nucleation theory.

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43

Paul, Jhon, B. Santhosh, E. N. Ananthapadmanabhan, and P. K. Das. "Safety assessment of the film boiling chemical vapor infiltration (FB-CVI) process through a system-theoretic accident model and process (STAMP)." Journal of Loss Prevention in the Process Industries 72 (September 2021): 104544. http://dx.doi.org/10.1016/j.jlp.2021.104544.

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44

Kanin, P. K., V. A. Ryazantsev, M. A. Lexin, A. R. Zabirov, and V. V. Yagov. "Heat transfer enhancement at increasing water concentration in alcohol in the process of non-stationary film boiling." Journal of Physics: Conference Series 980 (March 2018): 012029. http://dx.doi.org/10.1088/1742-6596/980/1/012029.

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45

Sedlak Mosesson, Michal, Bo Alfredsson, and Pål Efsing. "Simulation of Slip-Oxidation Process by Mesh Adaptivity in a Cohesive Zone Framework." Materials 14, no. 13 (June 23, 2021): 3509. http://dx.doi.org/10.3390/ma14133509.

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Adaptive oxide thickness was developed in a cohesive element based multi-physics model including a slip-oxidation and diffusion model. The model simulates the intergranular stress corrosion cracking (IGSCC) in boiling water reactors (BWR). The oxide thickness was derived from the slip-oxidation and updated in every structural iteration to fully couple the fracture properties of the cohesive element. The cyclic physics of the slip oxidation model was replicated. In the model, the thickness of the oxide was taken into consideration as the physical length of the cohesive element. The cyclic process was modelled with oxide film growth, oxide rupture, and re-passivation. The model results agreed with experiments in the literature for changes in stress intensity factor, yield stress representing cold work, and environmental factors such as conductivity and corrosion potential.

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Kobasko, Nikolai. "DESIGNING OF ADVANCED AND ORIGINAL AUSTEMPERING PROCESSES BASED ON THERMAL SCIENCE AND ENGINEERING PHYSICS APPROACHES." EUREKA: Physics and Engineering 2 (March 31, 2016): 43–50. http://dx.doi.org/10.21303/2461-4262.2016.00060.

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In the paper, a small concentration of inverse solubility polymers in water and other liquid media is recommended to eliminate film boiling by means of reducing initial heat flux density. Quenching steel parts and tools in a small concentration of water solutions under pressure allows performing austempering process just using cold liquids. Its essence consists in coinciding martensite start temperature MS with the average temperature of self-regulated thermal process during nucleate boiling mode and further immediate transferring steel parts for tempering at the temperature which exceeds value MS. The new technology increases the service life of austempered workpieces by more than two times, saves alloy elements, is suitable for larger metallic components, improves environmental conditions, since instead of melted salts and alkali, plain water and water salt solutions can be used. The new austempering process can be used in forging shops to obtain super-strengthened materials in order to switch from alloy steel to plain carbon steels. And it can be also widely used for obtaining nano - bainitic structure in plain carbon steels resulting in saving alloy elements and improving mechanical characteristics of materials.

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47

Ni, Peiwei, Zhi Wen, Fuyong Su, Xunliang Liu, and Guofeng Lou. "Breaking process of boiling film around a solid hot sphere immersed in forced convection of sub-cooled water." International Journal of Heat and Mass Transfer 158 (September 2020): 120064. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2020.120064.

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48

Uemura, Mitsuhiro. "Enhancement of Forced Convection Subcooled Film Boiling Heat Transfer Using Gas Sheet Collapse by Electric Field Application." International Journal of Air-Conditioning and Refrigeration 26, no. 02 (June 2018): 1850011. http://dx.doi.org/10.1142/s2010132518500116.

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Enhancement of forced-convection boiling heat transfer by electric field is investigated experimentally. When a high-temperature horizontal filament is immersed in water, a gas sheet is formed around and the above filament due to liquid boiling, in the early immersion process. This gas-sheet markedly decreases the boiling cooling rate of the filament. Here, forced collapse of the gas sheet is attempted by imposing an electric field to enhance the boiling cooling rate, In the experiments, a horizontal platinum wire of 0.5[Formula: see text]mm in diameter is immersed in pure water under atmospheric pressure, and a DC voltage up to 600[Formula: see text]V is applied between the wire surface and an electrode made of glass placed 10[Formula: see text]mm apart. The whole boiling curve is measured under different applied voltages and wire-falling velocities in 0.5 to 2.0[Formula: see text]m/s range, and at subcooling of 60[Formula: see text]K. The experimental results show that the electric field is effective in promoting the disintegration of the gas sheet. Under the tested conditions, boiling cooling rate increased two-fold for an applied electric field of 600[Formula: see text]V/cm. This result shows that the use of an electric field to break up the gas-sheet has resulted in a remarkable increase in the cooling rate at high superheats during initial cooling period, which is even greater than that used in the existing material manufacturing processes by the rapid cooling method, and therefore, this method may contribute to developing new materials.

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Jiang, Wei Hui, Qi Ming Jiang, Jian Min Liu, Qing Xia Zhu, and Quan Zhang. "Prepartion of Stabilized Aluminum Titanate Film via Nonhydrolytic Sol-Gel Route." Advanced Materials Research 538-541 (June 2012): 96–100. http://dx.doi.org/10.4028/www.scientific.net/amr.538-541.96.

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The stabilized aluminum titanate (Al2TiO5) film was coated on the silicon carbide (SiC) substrate via nonhydrolytic sol-gel method (NHSG), using anhydrous aluminum chloride and titanium tetrachloride as precursors, ethanol as oxygen donor, different iron sources as stabilizers, and dimethyl mixed dibasic acid (DBE) with the characteristic of environmental protection and high boiling point as solvent. The phase transformation of modified Al2TiO5 xerogel during heat treatment, the effect of different iron stabilizers on the stabilization of Al2TiO5 film, and the influence of the coating process parameters on film-forming quality were investigated by means of DTA/TG, XRD and SEM. The results indicate that ethanol iron as the stabilizer, Al2TiO5 crystal phase can be formed at 750°C. While the temperature is raised further to 1000°C, Al2TiO5 is stable without decomposition, and has better synthesis effect. Selecting iron chloride, iron sulfate and iron ethanol as stabilizers respectively, only iron ethanol is effective to thermal stability of Al2TiO5 film. The best optimal vertical sliding velocity is 3.75 mm/s.

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Oliveira, de, Machado Ochoski, Conrado Chiarello, Dos Nunes, Silva da, Dos Dias, and Alves Antonini. "Experimental study of hydrodynamic parameters regarding on geyser boiling phenomenon in glass thermosyphon using wire-mesh sensor." Thermal Science, no. 00 (2021): 221. http://dx.doi.org/10.2298/tsci201008221o.

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The thermosyphon is a type of heat exchanger that has been widely used in many applications. The use of thermosyphons has been intensified in recent years, mainly in the manufacture of solar collectors and various industrial activities. A thermosyphon is a vertical sealed tube filled with a working fluid, consisting of, from bottom to top, by an evaporator, an adiabatic section, and a condenser. The study of geyser-boiling phenomena, which occurs inside the thermosyphon is of extreme importance, therefore the experimental analysis of the parameters related to the two-phase flow (liquid-steam), such as void fraction, bubble frequency, bubble velocity, and bubble length are necessary, since these parameters have a significant influence on heat transfer. In this work, a pair of wire mesh sensors was used, a relative innovative technology to obtain experimental values of the reported quantities for measuring these parameters of slug flow in thermosyphons. An experimental setup is assembled and the sensors are coupled to the thermosyphon enabling the development of the experimental procedure. Here is presented an experimental study of a glass thermosyphon instrumented with two Wire-Mesh Sensors, in which the aforementioned slug flow hydrodynamic parameters inherent to the geyser type boiling process are measured. It was measured successfully, as a function of the heat load (110, 120, 130, 140, and 150W), the void fraction (instantly and average), liquid film thickness, translation velocity of the elongated bubbles, lengths of the bubbles, and the liquid slug (displaced by the bubble rise up). It was observed that the higher the heat load, the lower is the bubble translation velocity. For all heat loads, based on the measured length of liquid slug (consequent displacement of liquid volume), caused by bubbles rise from evaporator to condenser, it could be affirmed to some extent that both boiling regime (pool and film) exist in the evaporator. The measured average void fraction (80%) and liquid film thickness (around 2.5mm) during the elongated bubble passages were approximately constant and independent of the heat load.

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Journal articles on the topic 'Film-boiling process'

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