Characteristic features of the boiling of emulsions having a low-boiling dispersed phase

The results of investigation of heat transfer from thin wires to a boiling emulsion, the dispersed phase of which is formed from a liquid with a boiling temperature much lower than the boiling temperature of the dispersion medium, are presented. Two variants of boiling of such an emulsion are possible: boiling of the dispersed phase alone and simultaneous boiling of the dispersed phase and dispersion medium. In the present work, only the first variant has been studied; it is distinguished by the following most important features: high superheat of the dispersed-phase droplets ΔT_sup of the emulsion and a wide temperature range of bubble boiling (50–200°C). For conventional heat carriers (pure liquids and solutions), the value of ΔT_sup does not exceed 1–10°C, with the bubble-boiling interval lying within the range from 5 to 20°C. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 6, pp. 81–84, November–December, 2006.     

Critical thermal load in saturated boiling of liquids

The critical velocity of vapor flow from the heating surface in boiling is found based on the analogy of bubbling and boiling phenomena. The relation for the critical thermal load q_cr is found from the assumption that this quantity corresponds to the maximum vapor velocity. The expression obtained in this work for q_cr describes experimental data on the saturated boiling of water, ethanol, and benzene at different pressures. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 81, No. 2, pp. 259–263, March–April, 2008.     

Residence-time distribution of particles in the post of a circulating boiling bed

The residence-time distributions of particles in the lifting post of a circulating boiling bed were calculated on the basis of a model of longitudinal mixing of particles in this bed. It is shown that this model is well approximated by the standard γ-distribution. The dependence of the residence-time distribution function on the main parameters of the circulating boiling bed has been determined. The calculated and experimental distribution functions were compared. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 3, pp. 164–170, May–June, 2006.     

Condensation charging of aerosol particles in the course of their formation in the gas phase

The behavior of aerosols formed over boiling melts of substances (boiling temperature 500–1800 K) in a stream of a carrier gas at 300 K was studied. Microparticles of size from 0.2 to 10 μm, partially aggregated, were detected in the aerosol. In an applied electric field with an intensity of 150–1000 V cm⁻¹, the particles migrated toward the negatively charged electrode at a velocity of 5–15 cm s⁻¹. The velocity of their motion was a linear function of the field intensity and depended on the melt boiling temperature in accordance with the Arrhenius equation. Experimental data were interpreted on the basis of a concept that, in the course of the growth of each microparticle, vapor molecules adsorbed by it decompose into ions with nonequivalent transfer of cations and anions into the particle volume, i.e., the microparticles undergo growth charging at the activation energy of the cation release from the particle surface into vapor of approximately 0.5 eV.     

Initial superheating of a liquid in boiling on a porous surface

A new model of boiling of a liquid on porous surfaces is proposed based on which a dependence for the superheating of the liquid at the beginning of boiling is derived. The effect of regime and structural parameters on the initial superheating is analyzed. The results obtained are compared with experimental data. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 71, No. 1, pp. 173–175, January–February, 1998.     

Influence of the Operating Time of a Surface Heated by Electric Current on the Heat-Transfer Coefficient of Kerosene and Water Boiling on It

Results of experimental investigation of the influence of the operating time of a heating surface on the intensity of heat transfer in the kerosene and water boiling on it are presented. The experimental data on the heat transfer in the indicated liquids boiling on unrun heating surfaces have been generalized using different relations. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 78, No. 3, pp. 134–140, May–June, 2005.     

Subcooled liquid boiling heat transfer under conditions of stepwise heat-load release

The results of experimental investigations of the effect of liquid subcooling below the saturation temperature on boiling heat transfer under conditions of an increase in a heating load are presented. Water and TS-1 kerosene were used as heat carriers. The obtained experimental data on subcooled liquid boiling heat transfer has been generalized by an empirical relation. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 80, No. 1, pp. 136–139, January–February, 2007.     

Heat transfer in boiling of water in a fill of spherical elements

An experimental study has been made of heat exchange in bubble and transient regimes of boiling in spherical-element fills as applied to the cores of nuclear reactors with spherical fuel microelements based on uranium dioxide with multilayer ceramic coatings. Critical dependences describing experimental data and making it possible to calculate the heat-transfer coefficient in such regimes of boiling have been obtained. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 80, No. 4, pp. 35–39, July–August, 2007.     

Boiling characteristics of emulsions with a low-boiling dispersed phase and surfactants

Results of measurement of heat-transfer coefficients are reported for the case of boiling of a dispersed phase of a water— PèS-5 emulsion on the surface of electrically heated thin platinum wires. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 70, No. 2, pp. 184–186, March–April, 1997.     

Effect of prolonged stay of the heat-transfer surface in water on the critical heat flux under steady and stepwise heat-release conditions

The author presents results of experimental investigations of the effect of prolonged stay of the heattransfer surface in water on the first critical density of the heat flux in boiling under steady and stepwise heat-release conditions. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 73, No. 2, pp. 232–236, March–April, 2000.     

Transient Processes and Thermoacoustic Effects in Surface Boiling of a Liquid

The results of experimental investigation of the phenomenon of hysteresis and the prehistory of boiling on a cylindrical heater have been given. The transient processes associated with thermoacoustic effects in burnout of a liquid under natural convection have been considered. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 78, No. 4, pp. 22–26, July–August, 2005.     

Boiling of liquid in the cell of a jet printer

An approximate calculation of the main parameters of boiling of a liquid in the cell of a jet printer — the ejection velocity of a liquid drop and the limiting permissible (critical) heat flow density supplied to the thermoresistor — is carried out. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 71, No. 2. pp. 218–221, March–April, 1998.     

Heat transfer in pool boiling of propane under the conditions of different saturation pressures

The author presents results of an experimental investigation of heat transfer in pool boiling of propane on single horizontal tubes with a polished surface and with a porous coating under the conditions of different saturation pressures. It is shown that the effect of the pressure on the intensity of the heat transfer manifests itself differently on smooth and porous surfaces and depends on the heat-flux density; however this dependence is not monotonic. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 73, No. 2, pp. 244–249, March–April, 2000.     

Influence of microstructure on corrosion behavior of Ti–5%Ta–1.8%Nb alloy

This paper presents the results of a study on the influence of microstructure on the corrosion behavior of a α–β Ti–5%Ta–1.8%Nb alloy—a candidate material for use in high concentrations of boiling nitric acid. The “as cast” alloy had a lamellar structure and showed a corrosion rate of about 1.5 mpy. Thermo-mechanical processing of the cast alloy resulted in a structure of predominantly of equiaxed α with random distribution of fine β particles. This “reference” structure was further modified employing different heat treatments similar to that for commercial titanium alloys such as mill annealing, solution treatment and aging or over aging treatments. Corrosion rates evaluated in boiling nitric acid in the liquid, vapor and condensate phases, showed low values ∼1 mpy. Of these, the lowest corrosion rate (∼0.03 mpy) was exhibited by the structure with minimum amount of β phase, distributed in an equiaxed α matrix. This structure was obtained by aging of the solution treated “reference” alloy. Hence, solution treatment high in the α + β phase field followed by aging at a temperature low in the α + β phase field has been identified as the optimum treatment to obtain a microstructure with superior corrosion resistance.     

Corrosion behaviour of aluminium alloys in ethanol fuels

In this study, the corrosion behaviour of several aluminium alloys in ethanol fuels was investigated by immersion and polarization tests. The corrosion properties of cast aluminium alloys (Al–17wt%Si–4wt%Cu–Mg, Al–8wt%Si–3wt%Cu, Al–7wt%Si–Mg and Al–17wt%Si–4wt%Cu–Mg with a chemically deposited nickel layer) in ethanol blended gasoline fuels were examined at various ethanol and water contents and various temperatures. Electrochemical and gravimetric measurements revealed a pronounced acceleration of the corrosion process above the boiling point. Additions of water restrain the corrosion. Increasing the ethanol content and the temperature leads to a higher corrosion sensitivity of the aluminium alloys. Furthermore, the nickel layer is very protective in all tested fuels. For aluminium alloys, a theory of the corrosion process in ethanol blended gasoline fuels is proposed.     

Liquid Saturation Density from Simple Equations of State

Several simple equations of state, requiring only two input properties, have been studied in order to determine the liquid saturation density of 144 fluids of different kinds. This study includes old and new simple modifications of the van der Waals equation of state, and the Carnahan–Starling–Yelash–Kraska and Carnahan–Starling–Dieterici equations. The new simple modifications of the van der Waals equation give better overall results than some other more complex proposed equations, especially near the critical point. The recent equation proposed by Eslami including the boiling temperature and density as input parameters was also checked, and was found not to reproduce the critical point, but to give excellent results at intermediate or low temperatures. As a reference, the behavior of the well-known Soave– Redlich–Kwong and Peng–Robinson equations, and the more recent expression proposed by Mohsen-Nia et al. that requires three input parameters were also checked. The latter does not improve the accuracy of the Peng–Robinson equation, and very simple van-der-Waals type equations give better overall results.     

The nature of microbubble emission under subcooled water boiling

Under boiling of highly subcooled water at high heat flow rates, several authors have observed emission of numerous small (10–80 μm) bubbles. This phenomenon has been called as “microbubble emission.” In this paper we make an attempt to explain this phenomenon by emission on the surface and in the near-surface liquid layer of the residual air that has not been removed in the course of the water deaeration (degassing).     

Isobaric Vapor–Liquid Equilibria of 1-Butanol–p-Xylene System

Isobaric vapor–liquid equilibrium data were obtained for 1-butanol–p-xylene system at 97.3 kPa using a vapor recirculating type (modified Othmer’s) equilibrium still. The activity coefficients were obtained by taking into consideration vapor-phase imperfections. The experimental data for this system were tested for thermodynamic consistency and were correlated by various equations. The system forms a minimum boiling azeotrope.Paper presented at the Seventh Asian Thermophysical Properties Conference, August 23–28, 2004, Hefei and Huangshan, Anhui, P. R. China.     

Some regularities of the heat transfer in the process of cooling of a cutting zone by an emulsion fog

The dependence of the average diameter of the drops of an emulsion and their number in a unit volume on the conditions of emulsion-fog generation has been investigated. An individual drop is heated, when it comes into contact with a heated surface, to the boiling and evaporation temperatures. Under certain conditions, the total time of heating and evaporation of all drops making contact with a surface for 1 sec can be smaller than this time. In this case, active substances entering into the composition of the emulsion form a solid lubrication film on the surfaces of a piece, a chip, and a cutting tool. More than 50% of the total heat released can be removed due to the boiling and evaporation of emulsion drops from the cutting zone. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 3, pp. 179–182, May–June, 2006.