B 16 Baidakov, V. G. Nucleation at retrograde condensation [] / V. G. Baidakov, G. Sh. Boltachev // AIP Conference Proceedings. - 2000. - Vol. 534, Is. 1. - 295-298: graph. . - ISSN 0094-243X Рубрики: ФИЗИКА Кл.слова (ненормированные): NUCLEATION -- CONDENSATION -- SURFACE TENSION -- RETROGRADE CONDENSATION Аннотация: A binary Van-der-Waals solution is considered. Within the framework of the Gibbs and Van-der-Waals capillary theories under the conditions of constancy of the temperature and the composition the sise dependences of surface tension s(R) are calculated for critical nuclei of liquid and vapor. The phenomenon of "closure" of size dependences s(R) and the presence anomalously of high maximums on them are established |
F 17 Faizullin, M. Z. Vitrification and crystallization of low-temperature amorphous condensates of water and methane-water mixture / M. Z. Faizullin, V. P. Koverda // Russian Journal of Physical Chemistry A. - 2012. - Vol.86, №2. - С. 229-234 Рубрики: ФИЗИКА Кл.слова (ненормированные): VITRIFICATION -- CRYSTALLIZATION -- GAS HYDRATES Аннотация: Low-temperature condensates of water and water-methane mixture are studied in the temperature range of 65-200 K. Amorphous samples are obtained by molecular beam deposition under vacuum conditions on the substrate cooled with liquid nitrogen. The vitrification and crystallization temperatures are determined from the changes in the dielectric properties of the condensates upon heating. The kinetics of crystallization of amorphous water layers is studied by differential thermal analysis. The temperature conditions for the growth of thick methane crystalline hydrate layers during the low-temperature condensation of molecular water-gas mixture beams are found |
F 17 Faizullin, M. Z. Synthesis of methane hydrate at low-temperature condensation of molecular beams [Electronic resource] / M. Z. Faizullin, A. V. Reshetnikov, V. P. Koverda // Doklady Physics. - 2010. - Vol.55, №8. - P388-390 Рубрики: ФИЗИКА Кл.слова (ненормированные): AMORPHOUS SOLID WATER -- ICE |
S 34 Schmelzer, J. W. P. Kinetics of Condensation and Boiling: Comparison of Different Approaches / J. W. P. Schmelzer, V. G. Baidakov // Journal of Physical Chemistry B. - 2001. - Vol.105, №47. - С. 11595-11604 Рубрики: ФИЗИКА Кл.слова (ненормированные): CRITICAL CLUSTER -- GIBBS' METHOD -- VAN-DER-WAALS METHOD -- HILLIARD METHOD Аннотация: A comparative analysis of the results of determination of the work of critical cluster formation in nucleation theory for three different methods of evaluationGibbs' method (employing the capillarity approximation), the van der Waals−Cahn and Hilliard method, and a newly developed modified Gibbs approachis given. As a particular application, the processes of condensation and boiling in one-component fluids are analyzed. As a model system for comparison, van der Waals fluids are chosen. In addition to the work of critical cluster formation, the bulk properties of the critical clusters (drops or bubbles), their characteristic sizes, and the values of the surface tension are determined in dependence on the initial supersaturation in the system or, equivalently, on the size of the critical clusters. It is shown that latter two mentioned methods of determination of the work of critical cluster formation (the van der Waals−Cahn & Hilliard and the modified Gibbs approach) leadat least for the model system consideredto qualitatively and partly quantitatively equivalent results. Nevertheless, differences remain which may lead to quantitative deviations when applied to the determination of the steady-state nucleation rates and further basic characteristics of nucleation-growth processes. The possible origin of such deviations is discussed, and some further directions of analysis are anticipated |
L 88 Loop Heat Pipes for Cooling Systems of Servers / Yu. F. Maydanik, S. V. Vershinin, V. G. Pastukhov, S. Fried // IEEE Transactions on Components and Packaging Technologies. - 2010. - Vol.33, №2. - С. 416-423 Рубрики: ФИЗИКА Кл.слова (ненормированные): HEAT-TRANSFER DEVICE -- LHPs -- OPTERON CPUs Аннотация: Loop heat pipes (LHPs) are exceptionally efficient heat-transfer devices that employ a closed loop evaporation-condensation cycle that can be used to cool densely packed electronic systems that reject large quantities of heat, including computers and their central processing units (CPUs). Tests were carried out on miniature ammonia LHPs with a CPU thermal simulator using different ways of condenser cooling. The possibility of maintaining the cooled object temperatures between 40°C and 70°C with heat load changing from 100 to 320 W was demonstrated. Subsequent tests of these devices in a 1U computer with dual core advanced micro devices Opteron CPUs, dissipating between 95 and 120 W, have confirmed the advantages and heat transfer efficiency of LHP-based cooling systems used to cool CPU in 1U chassis |
S 82 Steady state operation of a copper–water LHP with a flat-oval evaporator / S. Becker, S. V. Vershinin, V. Sartre, E. Laurien, J. Bonjour, Yu. F. Maydanik // Applied Thermal Engineering. - 2011. - Vol.31, №5. - С. 686-695. - Библиогр.: с. 695 (24 ref.) Рубрики: ФИЗИКА Кл.слова (ненормированные): LOOP HEAT PIPE -- HEAT TRAHSFER -- EXPERIMENTAL STUDY Аннотация: In order to dissipate the heat generated by electronic boxes in avionic systems, a copper–water LHP with a flat-oval evaporator was fabricated and tested at steady state. The LHP consists of a flat shaped evaporator, 7 mm thick, including compensation chamber with attached heat exchanger. The condenser is cooled by forced convection of liquid. The variable parameters are the heat sink and ambient temperatures (20 and 55 °C), the orientation (−90° to +90° in two perpendicular planes) and the power input (0–100 W). Evaporator wall temperatures are higher when the evaporator is placed above the condenser. For heat sink and ambient temperature of 20 °C the evaporator wall temperature does not vary much with heat load for all measured elevations. But it fluctuates at heat sink and ambient temperature equal to 55 °C when the evaporator is placed below the condenser. The LHP total thermal resistance is governed by the condenser resistance. It decreases with increasing heat load, whatever the operating conditions, because the part of the condenser internal surface area used for condensation increases too. A minimum thermal resistance of 0.2 K/W was obtained. The maximum thermal resistance was 2.7 K/W \\\\expert2\\NBO\\Applied Thermal Engineering\\2011, v. 31, p.686.pdf |
C 51 Chernysheva, M. A. Heat transfer during condensation of moving steam in a narrow channel / M. A. Chernysheva, S. V. Vershinin, Yu. F. Maydanik // International Journal of Heat and Mass Transfer. - 2009. - Vol.52, №11-12. - С. 2437-2443 Рубрики: ФИЗИКА Кл.слова (ненормированные): INTUBE CONDENSATION -- TWO-PHASE FLOW -- LOOP HEAT PIPE Аннотация: The paper presents the results of experimental investigation of heat transfer and hydrodynamics during condensation of moving steam in a narrow channel of square cross-section 2 mm × 2 mm. The channel had a serpentine shape, the channel length was 660 mm. An experimental cell simulated conditions of heat transfer in the condenser of loop heat pipes. The steam velocity at the channel inlet ranged from 13 to 52 m/s, the pressure was 1 atm. The temperature of the cooling water varied from 70 to 95 °C. The annular flow pattern was noted in the whole range of the regime parameters. There was a clear boundary between the condensation zone and the zone occupied by the condensed phase downstream. Temperature has measured along the channel, and the heat-transfer coefficients have been determined. The coefficient values varied from 10,000 to 55,000 W/K m2 depending on the steam velocity at the channel inlet and the cooling temperature. The efficiency of the condenser – heat exchanger has been investigated |
B 27 Bartuli, E. Visual and instrumental investigations of a copper-water loop heat pipe [Электронный ресурс] / E. Bartuli, S. V. Vershinin, Yu. F. Maydanik // International Journal of Heat and Mass Transfer. - 2013. - Vol.61, №1. - P35-40 Рубрики: ФИЗИКА Кл.слова (ненормированные): CONDENSATION -- COPPER-WATER LOOP HEAT PIPE -- FLAT GAP CONDENSER Аннотация: Visual and instrumental investigations of the processes of condensation and redistribution of a working fluid in a loop heat pipe have been carried out. This paper presents the results of an experimental investigation of the heat transfer and hydrodynamics during the condensation of water vapor in a flat gap condenser measuring 80 × 40 × 1 mm. Investigations have been conducted at a condenser cooling temperature of 20, 40 and 60 °. During all operating modes a stratified two-phase flow and film condensation have been observed. The temperature field in the condenser has been measured, and the heat-transfer coefficients and the thermal resistances have been determined |
D 63 Disintegration of flows of superheated liquid films and jets [Electronic resource] / A. N. Pavlenko, V. P. Koverda, A. V. Reshetnikov, A. S. Surtaev, A. N. Tsoi, N. A. Mazheiko, K. A. Busov, V. N. Skokov // Journal of Engineering Thermophysics. - Bibliogr. : p. 192-193 (65 ref.) Рубрики: ФИЗИКА Кл.слова (ненормированные): CYLINDRICAL CHANNEL -- EXPERIMENTAL INVESTIGATIONs -- BOILING INCIPIENCE Аннотация: This paper represents results on investigating the dynamics of boiling and disintegration of superheated liquid films and jets. The first part deals with experimental study of boiling liquid outflow through short cylindrical and slit channels. Evolution of disintegration of a hot water jet flow is observed both at low and moderate superheating and at high and limit superheating, and also for vaporization mechanisms corresponding to these superheatings. Peculiarities of disintegration of jets through slit and cylindrical channels are noticed. Results on measuring the reactive thrust of the jet through a slit channel under different geometrical conditions behind the channel outlet are represented. The 1/f fluctuations in transient regimes of superheated liquid boiling and in transient regimes of behavior of the jet shape are found. The second part of this article represents results on experimental investigation of nonsteady heat transfer and dynamics of the development of crisis phenomena at boiling of a falling subcooled liquid film in the conditions of stepwise heat release. The experimental data were obtained using synchronized high-speed infrared thermography and video. It is shown that with growth and condensation of vapor bubbles, on the liquid film interface appear large-amplitude waves that lead to considerably increasing local intensity of heat transfer. New data on the boiling incipience temperature in a subcooled liquid film, depending on the heat flux density, are obtained. It is found that the development of boiling crisis is a result of appearance of local dry patches and their subsequent growth by the mechanism of longitudinal thermal conductivity in the heat transfer wall as the equilibrium heat flux density is exceeded \\\\expert2\\NBO\\Journal of Engineering Thermophysics\\2013, V.22, N 3. P. 174-193.pdf |
D 63 Disintegration of flows of superheated liquid films and jets [Электронный ресурс] / A. N. Pavlenko, A. S. Surtaev, A. N. Tsoi, V. P. Koverda, A. V. Reshetnikov, N. A. Mazheiko, K. A. Busov, V. N. Skokov // Journal of Engineering Thermophysics. - 2013. - Vol.22, №3. - С. 174-193. - Библиогр.: с. 190-193 (65 ref.) Рубрики: ФИЗИКА Кл.слова (ненормированные): SUPERHEATED LIQUID FILMS -- LIQUID BOILING -- JET SHAPE Аннотация: This paper represents results on investigating the dynamics of boiling and disintegration of superheated liquid films and jets. The first part deals with experimental study of boiling liquid outflow through short cylindrical and slit channels. Evolution of disintegration of a hot water jet flow is observed both at low and moderate superheating and at high and limit superheating, and also for vaporization mechanisms corresponding to these superheatings. Peculiarities of disintegration of jets through slit and cylindrical channels are noticed. Results on measuring the reactive thrust of the jet through a slit channel under different geometrical conditions behind the channel outlet are represented. The 1/f fluctuations in transient regimes of superheated liquid boiling and in transient regimes of behavior of the jet shape are found. The second part of this article represents results on experimental investigation of nonsteady heat transfer and dynamics of the development of crisis phenomena at boiling of a falling subcooled liquid film in the conditions of stepwise heat release. The experimental data were obtained using synchronized high-speed infrared thermography and video. It is shown that with growth and condensation of vapor bubbles, on the liquid film interface appear large-amplitude waves that lead to considerably increasing local intensity of heat transfer. New data on the boiling incipience temperature in a subcooled liquid film, depending on the heat flux density, are obtained. It is found that the development of boiling crisis is a result of appearance of local dry patches and their subsequent growth by the mechanism of longitudinal thermal conductivity in the heat transfer wall as the equilibrium heat flux density is exceeded. \\\\expert2\\NBO\\Journal of Engineering Thermophysics\\2013, V.22, N 3. P. 174-193.pdf |
F 17 Faizullin, M. Z. Preparation of gas hydrates by nonequilibrium condensation of molecular beams / M. Z. Faizullin, A. V. Vinogradov, V. P. Koverda // Technical Physics Letters . - 2013. - Vol.39, №9. - С. 783-786. - Bibliogr. : p. 786 (16 ref.) Рубрики: ФИЗИКА Кл.слова (ненормированные): CARBON DIOXIDE -- CRYSTALLIZATION TEMPERATURES -- DIELECTRIC PROPERTIES Аннотация: Layers of amorphous ice saturated with carbon dioxide were prepared by the deposition of molecular beams of water and gas onto a substrate cooled with liquid nitrogen. Their heating is accompanied by glass transition (softening) and subsequent spontaneous crystallization. The glass transition and crystallization temperatures were determined from the change in dielectric properties during heating. The heat effects of the transformations were detected using differential thermal analysis. The crystallization of amorphous layers under conditions of deep metastability leads to the formation of crystalline hydrates. The avalanche nucleation of crystallization sites captures the gas molecules; therefore, they are not displaced by the movement of the crystallization front |
F 17 Faizullin, M. Z. Properties of gas hydrates formed by nonequilibrium condensation of molecular beams [Electronic resource] / M. Z. Faizullin, A. V. Vinogradov, V. P. Koverda // High Temperature. - 2014. - Vol. 52, № 6. - С. 830-839. - Bibliogr. : p. 838-839 (36 ref.) Рубрики: ФИЗИКА Кл.слова (ненормированные): GLASS-TRANSITION -- AMORPHOUS SOLIDS -- AQUEOUS-SOLUTIONS Аннотация: Low-temperature crystallization of amorphous materials has been analyzed theoretically taking into account nonstationary nucleation. The kinetics of crystallization of amorphous water layers, formed by depositing molecular beams on a substrate cooled by liquid nitrogen, has been investigated by differential thermal analysis. The conditions of gas hydrate formation in low-temperature amorphous-ice layers saturated with carbon dioxide have been studied. The glass-transition and crystallization temperatures of the gas hydrates have been determined from the change in dielectric properties upon heating. Under the deep-metastability conditions, crystallization of water-gas layers leads to the formation of crystallohydrates. Gas molecules are captured by the avalanche-like nucleation of crystallization centers and, therefore, are not displaced by the moving crystal-melt interface. Gas-hydrate samples formed in nonequilibrium water-gas layers are convenient for studying their thermophysical properties \\\\expert2\\nbo\\High Temperature\\2014, v. 52, N 6, p.830-839.pdf |
B 16 Baidakov, V. G. Nucleation at retrograde condensation [Electronic resource] / V. G. Baidakov, G. Sh. Boltachev // AIP Conference Proceedinds "Nucleation and atmospheric aerosols 2000" : 15th International Conference. - Rolla, Missouri (USA), 2000. - Vol. 534. - С. 295 Рубрики: ФИЗИКА Кл.слова (ненормированные): NUCLEATIONS -- CONDENSATION -- SURFACE TENSION Аннотация: A binary Van-der-Waals solution is considered. Within the framework of the Gibbs and Van-der-Waals capillary theories under the conditions of constancy of the temperature and the composition the size dependences of surface tension are calculated for critical nuclei of liquid and vapor. The phenomenon of “closure” of size dependences and the presence anomalously of high maximums on them are established. \\\\expert2\\nbo\\AIP Conf. Proceedings, 2000\\2000. V. 534. P. 295.pdf |
F 17 Faizullin, M. Z. Hydrate formation in layers of gas-saturated amorphous ice [Electronic resource] / M. Z. Faizullin, A. V. Vinogradov, V. P. Koverda // Chemical Engineering Science. - 2015. - Vol. 130. - С. 135-143. - Bibliogr. : p. 142-143 (44 ref.) Рубрики: ФИЗИКА Кл.слова (ненормированные): AMORPHOUS ICE -- GAS HYDRATES -- CARBON DIOXIDE Аннотация: Layers of amorphous ice saturated with methane, ethane, propane and carbon dioxide were obtained by condensation of molecular beams of rarefied vapor and gas on a substrate cooled with liquid nitrogen. The amorphous state of such objects at low temperatures is stabilized by the high viscosity and the small value of the stationary nucleation rate of the crystal phase. Their heating in condition of high metastability is accompanied by spontaneous explosive crystallization, which leads to the formation of gas hydrates. Glass-transition and crystallization temperatures were determined by changes in their dielectric properties under heating. An increase in the gas content in layers of amorphous ice causes an increase in the crystallization temperature without any significant changes in the glass transition temperature. At atmospheric pressure in a liquid n-pentane medium the retention of gas hydrates was observed up to temperatures close to 273. K. Self-preservation ensured the retention of hydrates in a metastable state at temperatures exceeding considerably their equilibrium dissociation temperatures. Samples of gas hydrates obtained at a maximum gas flow rate during the deposition contained up to 15 mass % of methane, 12 mass % of ethane, 13 mass % of propane, and 23 mass % of carbon dioxide \\\\expert2\\nbo\\Chemical Engineering Science\\2015, v.130, p.135-143.pdf |
B 16 Baidakov, V. G. Nucleation at retrograde condensation [] / V. G. Baidakov, G. Sh. Boltachev // AIP Conference Proceedings. - 2000. - Vol. 534, Is. 1. - 295-298: graph. . - ISSN 0094-243X Рубрики: ФИЗИКА Кл.слова (ненормированные): NUCLEATION -- CONDENSATION -- SURFACE TENSION -- RETROGRADE CONDENSATION Аннотация: A binary Van-der-Waals solution is considered. Within the framework of the Gibbs and Van-der-Waals capillary theories under the conditions of constancy of the temperature and the composition the sise dependences of surface tension s(R) are calculated for critical nuclei of liquid and vapor. The phenomenon of "closure" of size dependences s(R) and the presence anomalously of high maximums on them are established |
F 17 Faizullin, M. Z. Vitrification and crystallization of low-temperature amorphous condensates of water and methane-water mixture / M. Z. Faizullin, V. P. Koverda // Russian Journal of Physical Chemistry A. - 2012. - Vol.86, №2. - С. 229-234 Рубрики: ФИЗИКА Кл.слова (ненормированные): VITRIFICATION -- CRYSTALLIZATION -- GAS HYDRATES Аннотация: Low-temperature condensates of water and water-methane mixture are studied in the temperature range of 65-200 K. Amorphous samples are obtained by molecular beam deposition under vacuum conditions on the substrate cooled with liquid nitrogen. The vitrification and crystallization temperatures are determined from the changes in the dielectric properties of the condensates upon heating. The kinetics of crystallization of amorphous water layers is studied by differential thermal analysis. The temperature conditions for the growth of thick methane crystalline hydrate layers during the low-temperature condensation of molecular water-gas mixture beams are found |
F 17 Faizullin, M. Z. Synthesis of methane hydrate at low-temperature condensation of molecular beams [Electronic resource] / M. Z. Faizullin, A. V. Reshetnikov, V. P. Koverda // Doklady Physics. - 2010. - Vol.55, №8. - P388-390 Рубрики: ФИЗИКА Кл.слова (ненормированные): AMORPHOUS SOLID WATER -- ICE |
S 34 Schmelzer, J. W. P. Kinetics of Condensation and Boiling: Comparison of Different Approaches / J. W. P. Schmelzer, V. G. Baidakov // Journal of Physical Chemistry B. - 2001. - Vol.105, №47. - С. 11595-11604 Рубрики: ФИЗИКА Кл.слова (ненормированные): CRITICAL CLUSTER -- GIBBS' METHOD -- VAN-DER-WAALS METHOD -- HILLIARD METHOD Аннотация: A comparative analysis of the results of determination of the work of critical cluster formation in nucleation theory for three different methods of evaluationGibbs' method (employing the capillarity approximation), the van der Waals−Cahn and Hilliard method, and a newly developed modified Gibbs approachis given. As a particular application, the processes of condensation and boiling in one-component fluids are analyzed. As a model system for comparison, van der Waals fluids are chosen. In addition to the work of critical cluster formation, the bulk properties of the critical clusters (drops or bubbles), their characteristic sizes, and the values of the surface tension are determined in dependence on the initial supersaturation in the system or, equivalently, on the size of the critical clusters. It is shown that latter two mentioned methods of determination of the work of critical cluster formation (the van der Waals−Cahn & Hilliard and the modified Gibbs approach) leadat least for the model system consideredto qualitatively and partly quantitatively equivalent results. Nevertheless, differences remain which may lead to quantitative deviations when applied to the determination of the steady-state nucleation rates and further basic characteristics of nucleation-growth processes. The possible origin of such deviations is discussed, and some further directions of analysis are anticipated |
L 88 Loop Heat Pipes for Cooling Systems of Servers / Yu. F. Maydanik, S. V. Vershinin, V. G. Pastukhov, S. Fried // IEEE Transactions on Components and Packaging Technologies. - 2010. - Vol.33, №2. - С. 416-423 Рубрики: ФИЗИКА Кл.слова (ненормированные): HEAT-TRANSFER DEVICE -- LHPs -- OPTERON CPUs Аннотация: Loop heat pipes (LHPs) are exceptionally efficient heat-transfer devices that employ a closed loop evaporation-condensation cycle that can be used to cool densely packed electronic systems that reject large quantities of heat, including computers and their central processing units (CPUs). Tests were carried out on miniature ammonia LHPs with a CPU thermal simulator using different ways of condenser cooling. The possibility of maintaining the cooled object temperatures between 40°C and 70°C with heat load changing from 100 to 320 W was demonstrated. Subsequent tests of these devices in a 1U computer with dual core advanced micro devices Opteron CPUs, dissipating between 95 and 120 W, have confirmed the advantages and heat transfer efficiency of LHP-based cooling systems used to cool CPU in 1U chassis |
S 82 Steady state operation of a copper–water LHP with a flat-oval evaporator / S. Becker, S. V. Vershinin, V. Sartre, E. Laurien, J. Bonjour, Yu. F. Maydanik // Applied Thermal Engineering. - 2011. - Vol.31, №5. - С. 686-695. - Библиогр.: с. 695 (24 ref.) Рубрики: ФИЗИКА Кл.слова (ненормированные): LOOP HEAT PIPE -- HEAT TRAHSFER -- EXPERIMENTAL STUDY Аннотация: In order to dissipate the heat generated by electronic boxes in avionic systems, a copper–water LHP with a flat-oval evaporator was fabricated and tested at steady state. The LHP consists of a flat shaped evaporator, 7 mm thick, including compensation chamber with attached heat exchanger. The condenser is cooled by forced convection of liquid. The variable parameters are the heat sink and ambient temperatures (20 and 55 °C), the orientation (−90° to +90° in two perpendicular planes) and the power input (0–100 W). Evaporator wall temperatures are higher when the evaporator is placed above the condenser. For heat sink and ambient temperature of 20 °C the evaporator wall temperature does not vary much with heat load for all measured elevations. But it fluctuates at heat sink and ambient temperature equal to 55 °C when the evaporator is placed below the condenser. The LHP total thermal resistance is governed by the condenser resistance. It decreases with increasing heat load, whatever the operating conditions, because the part of the condenser internal surface area used for condensation increases too. A minimum thermal resistance of 0.2 K/W was obtained. The maximum thermal resistance was 2.7 K/W \\\\expert2\\NBO\\Applied Thermal Engineering\\2011, v. 31, p.686.pdf |