The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
Zhen-hua Liu - One of the best experts on this subject based on the ideXlab platform.
-
Natural Convective Boiling in horizontal and inclined micro-channels structure using super-moist fluids for cooling 3D stacked chip
International Journal of Heat and Mass Transfer, 2017Co-Authors: Ping-yang Wang, Zhen-hua LiuAbstract:Abstract A novel micro-channels heat pipe technology which passively cools 3D chips was proposed. The micro-channels structure of 3D chips was used as the evaporating section of the heat pipe. The maximum heat flux and heat transfer coefficient of Boiling in horizontal and inclined micro-channels were studied experimentally studied. Experiments were carried out using four kinds of working liquids: two pure fluids (deionized water and R113) and two super-moist fluids (deionized water + surfactant and R113 + surfactant). The height and gap of channels used were in the range of 30–90 mm and 30–100 μm, respectively. Experimental results show that horizontal and inclined micro-channels structure can also cause great natural Convective Boiling to cool 3D chip, simultaneously, super-moist fluids can significantly enhance both the maximum heat flux and heat transfer coefficient of Boiling in micro-channels due to super-wettability of the liquids. The results show that the horizontal micro channel heat pipe structure is also a promising technology for 3D chip cooling.
-
Prediction of critical heat flux on natural Convective Boiling in vertical short‐thick tube submerged in saturated liquid
Heat Transfer?Asian Research, 2003Co-Authors: Zhen-hua LiuAbstract:An experimental and semitheoretical study was carried out for the critical heat flux (CHF) on natural Convective Boiling in uniformly heated vertical short-thick tubes and vertical short-thick annular tubes submerged in saturated liquids. By adapting a mathematical dealing method based on the theoretical formulas of CHF of both the natural Convective Boiling in vertical narrow-long tubes and the pool Boiling, a simple semitheoretical formula was derived. The new formula expands the prediction range of CHF from pool Boiling of vertical plates to very long vertical tubes and agrees well with the data of the tubes, annular tubes submerged in water or other liquids under various pressure conditions. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(5): 402–410, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.10103
-
Prediction of critical heat flux for Convective Boiling of saturated water jet impinging on the stagnation zone
Journal of Heat Transfer, 2002Co-Authors: Zhen-hua Liu, Qun-zhi ZhuAbstract:A theoretical analysis and an experimental investigation were carried out for predicting the critical heat flux (CHF) of Convective Boiling for a round saturated water jet impinging on the jet stagnation zone. The model of the maximum liquid subfilm thickness based on the Helmholtz instability is used to derive a semi-theoretical equation and the correlation factor was determined from the experimental data. Finally, a semi-theoretical correlation was proposed for predicting CHF of Convective Boiling for saturated water jet impinging on the jet stagnation zone
-
Natural Convective Boiling in vertical annular tubes filled with porous medium
Heat Transfer?Asian Research, 2000Co-Authors: Zhen-hua Liu, Yu‐ming ChenAbstract:Experimental and theoretical studies were carried out on the natural Convective Boiling heat transfer and critical heat flux (CHF) in uniformly heated vertical annular tubes filled with a porous medium and submerged in saturated water and R11 liquid. The heat transfer experimental results were compared with the case without a porous medium. It was shown that heat transfer is greatly enhanced by the porous medium in the region of low heat flux. By adopting a simple mixing flow model, a generalized approximate relationship was derived for predicting the CHF
Enio Pedone Bandarra Filho - One of the best experts on this subject based on the ideXlab platform.
-
Heat Transfer Coefficient Correlation for Convective Boiling Inside Plain and Microfin Tubes Using Genetic Algorithms
Heat Transfer Engineering, 2009Co-Authors: Marco Antonio Silva Picanço, Júlio César Passos, Enio Pedone Bandarra FilhoAbstract:Two-phase flow heat transfer has been exhaustively studied in recent years. However, in this field, several questions remain unanswered. Heat transfer coefficient prediction related to nucleate and Convective Boiling has been studied using different approaches—numerical, analytical, and experimental. In this study, an experimental analysis, data representation, and heat transfer coefficient prediction of two-phase heat transfer in nucleate and Convective Boiling are presented. An empirical correlation is obtained, based on a genetic algorithms search engine, of a dimensional analysis of the two-phase flow heat transfer problem.
-
Convective Boiling performance of refrigerant R-134a in herringbone and microfin copper tubes
International Journal of Refrigeration, 2006Co-Authors: Enio Pedone Bandarra Filho, José Maria Saiz JabardoAbstract:This paper reports an experimental investigation of Convective Boiling heat transfer and pressure drop of refrigerant R-134a in smooth, standard microfin and herringbone copper tubes of 9.52 mm external diameter. Tests have been conducted under the following conditions: inlet saturation temperature of 5 8C, qualities from 5 to 90%, mass velocity from 100 to 500 kg s K1 m K2 , and a heat flux of 5 kW m K2 . Experimental results indicate that the herringbone tube has a distinct heat transfer performance over the mass velocity range considered in the present study. Thermal performance of the herringbone tube has been found better than that of the standard microfin in the high range of mass velocities, and worst for the smallest mass velocity (GZ 100 kg s K1 m K2 ) at qualities higher than 50%. The herringbone tube pressure drop is higher than that of the standard microfin tube over the whole range of mass velocities and qualities. The enhancement parameter is higher than one for both tubes for mass velocities lower than 200 kg s K1 m K2 . Values lower than one have been obtained for both tubes in the mass velocity upper range as a result of a significant pressure drop increment not followed by a correspondent increment in the heat transfer coefficient.
-
Convective Boiling pressure drop of refrigerant r 134a in horizontal smooth and microfin tubes
International Journal of Refrigeration-revue Internationale Du Froid, 2004Co-Authors: Enio Pedone Bandarra Filho, José Maria Saiz Jabardo, Paulo E L BarbieriAbstract:Abstract Present study deals with the pressure drop of refrigerant R-134a under Convective Boiling conditions in horizontal smooth and microfinned (‘grooved’) copper tubes. Experiments have been carried out in an experimental set up developed for change of phase studies with a test section made out of 7.0, 7.93, and 9.52 mm external diameter, 1.5 m long copper tubes, electrically heated by tape resistors wrapped on the external surface. Mass velocities and refrigerant qualities varied in the following ranges: 70–1100 kg s −1 m −2 and 5–95%. The annular flow pattern has been observed to occur over most of the operational conditions. For smooth tubes, the Jung and Radermacher correlation for the liquid two phase flow multiplier fits with reasonable precision the experimental data. As for grooved tubes, a correlation of the two phase flow multiplier in terms of the Martinelli's parameter has been developed which fits the data with an average absolute deviation of the order of 6.3%. The proposed correlation fits with good precision data obtained elsewhere for grooved tubes of different diameter and microfin geometry.
-
Convective Boiling of halocarbon refrigerants flowing in a horizontal copper tube an experimental study
Experimental Thermal and Fluid Science, 2000Co-Authors: José Maria Saiz Jabardo, Enio Pedone Bandarra FilhoAbstract:Abstract An experimental study of Convective Boiling of refrigerants R-22, R-134a and R-404A in a 12.7 mm internal diameter, 2 m long, horizontal copper tube has been performed. Experiments involved a relatively wide range of operational conditions. Experiments were performed at the evaporating temperatures of 8°C and 15°C. Quality, mass velocity and heat flux varied in the following ranges: 5% to saturated vapor, 50– 500 kg /( s m 2 ); and 5– 20 kW / m 2 . Effects of these physical parameters over the heat transfer coefficient have been investigated. High quality experiments were also performed up to the point of the tube surface dryout, a mechanism which was investigated from the qualitative point of view. Two heat transfer coefficient correlations from the literature have been evaluated through comparisons with experimental data. Deviations varied in the range from −25% to 42%.
M. Kamalgharibi - One of the best experts on this subject based on the ideXlab platform.
-
Sedimentation and Convective Boiling heat transfer of CuO-water/ethylene glycol nanofluids
Heat and Mass Transfer, 2014Co-Authors: Mohammad Mohsen Sarafraz, Faramarz Hormozi, M. KamalgharibiAbstract:The Convective Boiling characteristics of dilute dispersions of CuO nanoparticles in water/ethylene glycol as a base fluid were studied at different operating conditions of (heat fluxes up to 174 kW m^−2, mass fluxes range of 353–1,059 kg m^−2 s^−1 and sub-cooling level of 343, 353 and 363 K) inside the annular duct. The Convective Boiling heat transfer coefficients of nanofluids in different concentrations (vol%) of nanoparticles (0.5, 1, and 1.5) were also experimentally quantified. Results demonstrated the significant augmentation of heat transfer coefficient inside the region with forced convection dominant mechanism and deterioration of heat transfer coefficient in region with nucleate Boiling dominant heat transfer mechanism. Due to the scale formation around the heating section, fouling resistance was also experimentally measured. Experimental data showed that with increasing the heat and mass fluxes, the heat transfer coefficient and fouling resistance dramatically increase and rate of bubble formation clearly increases. Obtained results were then compared to some well-known correlations. Results of these comparisons demonstrated that experimental results represent the good agreement with those of obtained by the correlations. Consequently, Chen correlation is recommended for estimating the Convective flow Boiling heat transfer coefficient of dilute CuO-water/ethylene glycol based nanofluids.
-
sedimentation and Convective Boiling heat transfer of cuo water ethylene glycol nanofluids
Heat and Mass Transfer, 2014Co-Authors: Mohammad Mohsen Sarafraz, Faramarz Hormozi, M. KamalgharibiAbstract:The Convective Boiling characteristics of dilute dispersions of CuO nanoparticles in water/ethylene glycol as a base fluid were studied at different operating conditions of (heat fluxes up to 174 kW m−2, mass fluxes range of 353–1,059 kg m−2 s−1 and sub-cooling level of 343, 353 and 363 K) inside the annular duct. The Convective Boiling heat transfer coefficients of nanofluids in different concentrations (vol%) of nanoparticles (0.5, 1, and 1.5) were also experimentally quantified. Results demonstrated the significant augmentation of heat transfer coefficient inside the region with forced convection dominant mechanism and deterioration of heat transfer coefficient in region with nucleate Boiling dominant heat transfer mechanism. Due to the scale formation around the heating section, fouling resistance was also experimentally measured. Experimental data showed that with increasing the heat and mass fluxes, the heat transfer coefficient and fouling resistance dramatically increase and rate of bubble formation clearly increases. Obtained results were then compared to some well-known correlations. Results of these comparisons demonstrated that experimental results represent the good agreement with those of obtained by the correlations. Consequently, Chen correlation is recommended for estimating the Convective flow Boiling heat transfer coefficient of dilute CuO-water/ethylene glycol based nanofluids.
Mohammad Mohsen Sarafraz - One of the best experts on this subject based on the ideXlab platform.
-
Sedimentation and Convective Boiling heat transfer of CuO-water/ethylene glycol nanofluids
Heat and Mass Transfer, 2014Co-Authors: Mohammad Mohsen Sarafraz, Faramarz Hormozi, M. KamalgharibiAbstract:The Convective Boiling characteristics of dilute dispersions of CuO nanoparticles in water/ethylene glycol as a base fluid were studied at different operating conditions of (heat fluxes up to 174 kW m^−2, mass fluxes range of 353–1,059 kg m^−2 s^−1 and sub-cooling level of 343, 353 and 363 K) inside the annular duct. The Convective Boiling heat transfer coefficients of nanofluids in different concentrations (vol%) of nanoparticles (0.5, 1, and 1.5) were also experimentally quantified. Results demonstrated the significant augmentation of heat transfer coefficient inside the region with forced convection dominant mechanism and deterioration of heat transfer coefficient in region with nucleate Boiling dominant heat transfer mechanism. Due to the scale formation around the heating section, fouling resistance was also experimentally measured. Experimental data showed that with increasing the heat and mass fluxes, the heat transfer coefficient and fouling resistance dramatically increase and rate of bubble formation clearly increases. Obtained results were then compared to some well-known correlations. Results of these comparisons demonstrated that experimental results represent the good agreement with those of obtained by the correlations. Consequently, Chen correlation is recommended for estimating the Convective flow Boiling heat transfer coefficient of dilute CuO-water/ethylene glycol based nanofluids.
-
sedimentation and Convective Boiling heat transfer of cuo water ethylene glycol nanofluids
Heat and Mass Transfer, 2014Co-Authors: Mohammad Mohsen Sarafraz, Faramarz Hormozi, M. KamalgharibiAbstract:The Convective Boiling characteristics of dilute dispersions of CuO nanoparticles in water/ethylene glycol as a base fluid were studied at different operating conditions of (heat fluxes up to 174 kW m−2, mass fluxes range of 353–1,059 kg m−2 s−1 and sub-cooling level of 343, 353 and 363 K) inside the annular duct. The Convective Boiling heat transfer coefficients of nanofluids in different concentrations (vol%) of nanoparticles (0.5, 1, and 1.5) were also experimentally quantified. Results demonstrated the significant augmentation of heat transfer coefficient inside the region with forced convection dominant mechanism and deterioration of heat transfer coefficient in region with nucleate Boiling dominant heat transfer mechanism. Due to the scale formation around the heating section, fouling resistance was also experimentally measured. Experimental data showed that with increasing the heat and mass fluxes, the heat transfer coefficient and fouling resistance dramatically increase and rate of bubble formation clearly increases. Obtained results were then compared to some well-known correlations. Results of these comparisons demonstrated that experimental results represent the good agreement with those of obtained by the correlations. Consequently, Chen correlation is recommended for estimating the Convective flow Boiling heat transfer coefficient of dilute CuO-water/ethylene glycol based nanofluids.
-
Qualitative investigation of the Convective Boiling heat transfer of dilute Al2O3- water/glycerol solution inside the vertical annuli
2014Co-Authors: Mohammad Mohsen Sarafraz, Faramarz HormoziAbstract:In this work, the flow Boiling heat transfer coefficient of Al2O3-water/glycerol nanofluids was experimentally investigated under different operating conditions. The influence of different operating parameters such as heat flux, mass flux and sub-cooling temperature, as well as concentration of nanofluids on the Convective Boiling heat transfer coefficient was studied and discussed. The results demonstrated that two heat transfer regions with different heat transfer mechanisms can be distinguished during the Convective Boiling of nanofluids, namely single-phase forced convection and two-phase nucleate Boiling. The results also showed that with increasing the heat and mass fluxes, the heat transfer coefficient of nanofluid increases and with increasing the nanofluid concentration, the heat transfer coefficient decreases which is due to the deposition of nanoparticles on the heater surface. The sub-cooling temperature only influences the onset of nucleate Boiling.
Zengyuan Guo - One of the best experts on this subject based on the ideXlab platform.
-
natural Convective Boiling in vertical rectangular narrow channels
Experimental Thermal and Fluid Science, 1996Co-Authors: Chunlin Xia, Zengyuan GuoAbstract:Abstract Natural Convective Boiling in a confined narrow space is frequently encountered in engineering, but there is as yet very little information on heat transfer enhancement obtained from Boiling in vertical narrow channels with symmetric heating. To understand the heat transfer mechanism of Boiling in the channels, experiments were performed for saturated R-113 at heat flux from very low to critical in vertical narrow channels under atmospheric pressure. The channels consist of a pair of flat plates, either transparent or porcelain. The plates were covered with a plating electric heating film by a new technique. The effects of gap sizes, channel heights, and heat fluxes on heat transfer and critical heat flux (CHF) were studied systematically. The results based on observation and measurement illustrate that the smaller the gap size, the smaller the incipient heat flux. The Boiling flow pattern depends on gap sizes and heat fluxes. The point of maximum wall superheat is not always located on the top of the Boiling surface. Wall superheat decreases as the channel narrows at the lower heat fluxes, but the reverse holds at the higher heat fluxes. For a heating channel, there exists an optimum channel size for heat transfer enhancement A increase in channel height has the same effect on heat transfer behavior as a decrease in gap size. The CHF decreases with decreasing gap size or increasing channel height. The fact that the mass velocity in the channel falls off sharply upon heating might be related to the Boiling crisis.