Heat Transfer: Volume 3 — Experimental Studies in Multiphase Flow; Multiphase Flow in Porous Media; Experimental Multiphase Flows and Numerical Simulation of Two-Phase Flows; Fundamental Aspects of Experimental Methods最新文献

{"title":"A Study of Intermittent Flow in Downward Inclined Pipes","authors":"Jiede Yang, C. Sarica, Xuanzheng T. Chen, J. P. Brill","doi":"10.1115/imece1996-0101","DOIUrl":"https://doi.org/10.1115/imece1996-0101","url":null,"abstract":"\u0000 The downward simultaneous flow of gas and liquid is often encountered in hilly terrain pipelines and steam injection wells. Most of the available methods for predicting the behavior of gas-liquid flow in pipes have been developed for horizontal and upward inclined pipes. In this study, co-current steady state slug flow in downward inclined pipes is investigated, experimentally and theoretically. A series of slug flow experiments are conducted with an air-kerosene system in a 2-in. diameter, 75-ft long pipe installed on an inclinable structure. Liquid holdup and pressure drop measurements are obtained for downward inclination angles from 0° to −90° at different flow conditions. Correlations for slug flow characteristics are obtained based on the experimental data. A mechanistic model based on a unit cell approach has been proposed for the prediction of the detailed slug structure, and subsequently the pressure gradient.\u0000 Fully developed slug flow could not be observed from −50° to −90°. A correlation was obtained for slug liquid holdup, and an analytical model and a correlation were developed for slug translational velocity. The lognormal distribution was found to best fit all the experimental slug length data. Equations for mean and design slug length were derived from the lognormal distribution function for inclination angles ranging from 0° to −30°. A slug frequency correlation was also developed.\u0000 The model can be used to predict intermittent flow behavior in downward inclined pipes. The correlations for slug liquid holdup, slug translational velocity, and slug length and frequency are closure relationships applicable to any model. Slug frequency information is also imperative for erosion and corrosion rate predictions.","PeriodicalId":324954,"journal":{"name":"Heat Transfer: Volume 3 — Experimental Studies in Multiphase Flow; Multiphase Flow in Porous Media; Experimental Multiphase Flows and Numerical Simulation of Two-Phase Flows; Fundamental Aspects of Experimental Methods","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122360197","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Critical Heat Flux During Subcooled Flow Boiling in Narrow Rectangular Channels","authors":"Ryo Nakajima, N. Ramanujapu, V. Dhir","doi":"10.1115/imece1996-0098","DOIUrl":"https://doi.org/10.1115/imece1996-0098","url":null,"abstract":"\u0000 The critical heat flux during subcooled flow boiling in narrow one-side heated rectangular channels was investigated experimentally using fluorinert liquid PF-5060 as a coolant. Three channel widths were examined, that is 1.3mm, 2.0mm, and 3.0mm. The heating surface was 10mm wide and 200mm long and only vertical upflow was experimented. Experiments were conducted at nearly atmospheric pressure under the following conditions: subcooled coolant mass velocity 2000–5000 kg/m2s; inlet temperature 24–47 °C; exit pressure 1.0–1.4 bar; equilibrium quality at channel exit −0.58 to −0.28.\u0000 Critical heat flux under the above experimental conditions was found to increase with increase in mass velocity, with decrease in the channel width, and with increase in the inlet subcooling. Visual observations showed that bubbles were small and had diameter less than 100μm. A comparison of the data with correlations reported in the literature showed that the correlations generally tended to overpredict the data. The correlations also do not show a proper trend with respect to the effect of channel width on critical heat flux. A new correlation based on dimensional analysis has been proposed. The correlation proposed can predict experimental data within 20% uncertainty.","PeriodicalId":324954,"journal":{"name":"Heat Transfer: Volume 3 — Experimental Studies in Multiphase Flow; Multiphase Flow in Porous Media; Experimental Multiphase Flows and Numerical Simulation of Two-Phase Flows; Fundamental Aspects of Experimental Methods","volume":"122 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128180521","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Measurement of Local Mass Flux in a Circulating Fluidized Bed Using a Phase Doppler Particle Analyzer: A New Post-Processing Data Algorithm","authors":"T. V. D. Moortel, R. Santini, L. Tadrist","doi":"10.1115/imece1996-0117","DOIUrl":"https://doi.org/10.1115/imece1996-0117","url":null,"abstract":"\u0000 This study focused on the measurement of solid mass flux in the riser of a CFB cold pilot. The investigations were carried out using a Phase Doppler Particle Analyzer (PDPA). Inconsistencies in PDPA results were observed when investigating flows with high particle densities. It appears that the performance of the measuring technique was affected by the optical thickness of the measured medium, thus producing substantial overestimation of the global solid phase quantity (e.g., solid mass flux). To determine the origin of these inconsistencies, the measuring system was subjected to complete recalibration. It was found that in flows with high particle densities, noisy doppler signals tend to be split into several parts by the burst detector system, thus producing inconsistencies in the number of particles counted. The parameters associated with the splitting events were analyzed, and a post-processing algorithm was developed to limit PDPA measuring errors. The aim of the post-processing algorithm was to rebuild the data and to recover the original measurements. The reconstitution process was applied to solid mass flux measurements in a CFB cold pilot.","PeriodicalId":324954,"journal":{"name":"Heat Transfer: Volume 3 — Experimental Studies in Multiphase Flow; Multiphase Flow in Porous Media; Experimental Multiphase Flows and Numerical Simulation of Two-Phase Flows; Fundamental Aspects of Experimental Methods","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124334635","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A General Governing Equation for Flow of Fluids in Porous Media","authors":"S. Moaveni","doi":"10.1115/imece1996-0121","DOIUrl":"https://doi.org/10.1115/imece1996-0121","url":null,"abstract":"A general differential equation governing the motion of a fluid through porous media is formulated by applying the momentum balance to a formal control volume. The porous medium in the control volume is modeled as an assemblage bundle of hypothetical conduits through which fluid is transported across the medium. The momentum equation employed, will account for the rate of momentum influx and efflux by virtue of the bulk fluid motion in and out of control volume. This formulation will also take into consideration a net shear force acting on the surface of the control volume. The pressure forces acting on the fluid surfaces of the volume element and the resultant viscous force of the fluid acting on the interior wetted surfaces of hypothetical conduits are also included in the model. Furthermore, it is shown that equation of motion reduces to the familiar Darcy’s Law for slow flow rates; for higher velocities, it transforms into Forchheimer relationship. For non-uniform velocity fields, the governing equation yields additional cross-stream-inertia term and a drag term which do not appear in other formulations. In the absence of inertia effects, the derived equation of motion reduces to Brinkman’s findings. In addition, the individual coefficients of the expressions in the momentum equation are explicitly derived in terms of fluid properties, size characteristics of a given medium and some unknown coefficients. A procedure for extracting the unknown coefficients will also be discussed.","PeriodicalId":324954,"journal":{"name":"Heat Transfer: Volume 3 — Experimental Studies in Multiphase Flow; Multiphase Flow in Porous Media; Experimental Multiphase Flows and Numerical Simulation of Two-Phase Flows; Fundamental Aspects of Experimental Methods","volume":"61 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124872330","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Fluid Dynamics Study of a Circulating Fluidized Bed With Secondary Air Injection","authors":"A. Pécora, L. Goldstein","doi":"10.1115/imece1996-0122","DOIUrl":"https://doi.org/10.1115/imece1996-0122","url":null,"abstract":"\u0000 This paper presents an experimental study on the fluid dynamics of a circulating fluidized bed with secondary air injection. The experiments were run in a 4 m high, 100 mm internal diameter riser system. The solid material was 200–920 μm diameter sand. The gas temperature at the beginning of the riser was around 200°C and the superficial gas velocity varied in the 2.5–9.5 m/s range. The data obtained made possible to suggest correlations for the pressure drop in a cyclone and in a recirculating L-valve, which are necessary to study the system pressure balance. The pressure profiles in the loop of the circulating fluidized system show the secondary air injection influence.","PeriodicalId":324954,"journal":{"name":"Heat Transfer: Volume 3 — Experimental Studies in Multiphase Flow; Multiphase Flow in Porous Media; Experimental Multiphase Flows and Numerical Simulation of Two-Phase Flows; Fundamental Aspects of Experimental Methods","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116488855","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Local and Non-Local Correlations for Critical Heat Flux at Low and Medium Pressures","authors":"T. Jafri, T. Dougherty, B. W. Yang","doi":"10.1115/imece1996-0116","DOIUrl":"https://doi.org/10.1115/imece1996-0116","url":null,"abstract":"\u0000 The local and non-local correlations [1] developed based on more than 10,000 Critical Heat Flux (CHF) data points arc reviewed and the effects of the pressure and Peclet number are examined under low and medium pressure conditions (up to 110 bar).\u0000 Examination of CHF data from many sources covering a wide range of operating conditions, reveals that both local and non-local CHF data exist with different dependencies on operating conditions, and different correlations are required to represent these data. These two distinct types of correlations imply the existence of at least two distinct mechanisms for CHF. Instead of the equilibrium quality, X, the true mass fraction, Xt, based on a non-equilibrium, homogeneous model, was used in developing the CHF correlations. The true mass fraction was calculated from a simple kinetic model based on an extension of the Saha-Zuber (S-Z, 1974) correlation for the Onset of Significant Vaporization (OSV). In this model, Xt is a function of exit equilibrium quality, X; the quality at OSV, Xo, and the quality at which significant vaporization begins Xb; estimated from the Saha-Zuber (S-Z) correlation. This model contains no adjustable parameters. When Xi < Xo (both negative), Xb = Xo and Xt is independent of Xi, and is a function of local variables only. When CHF is determined by local conditions (G, Xt, and P), the correlation is a local correlation. For Xi > Xo, Xb = Xi, and Xt depends on Xi, a nonlocal variable, and, in this case, CHF, even when determined by local conditions (G, Xt, and P), obeys a nonlocal correlation. This model appears to be satisfactory for pressures less than 110 bar, where the S-Z correlation is known to be reliable. Above 110 bar the method of calculating Xo, and consequently Xt, appears to fail. This paper will focus on the low pressure range, pressures up to 35 bar or 500 psia, and medium pressure range, pressures from 35 (500 psia) to 110 bar (1500 psia).\u0000 In this study, two regimes of CHF are observed which will be referred to as the high CHF regime and the low CHF regime. In the high CHF regime, for pressures less than 110 bar, CHF (qc) is determined by local conditions and is accurately represented by qc = (1.2/D1/2)exp[-γ(GXt)1/2], where the parameter γ is an increasing function of pressure only. Most of the medium pressure CHF data, but not all, fall in this regime.\u0000 For the medium pressure range, 500 psia to 1500 psia, the pressure dependency is given by γ = 0.12 (P/Pc)1/2. Below 35 bar (500 psia), based on the limited amount of local CHF data, the pressure dependency of this local condition appears to be very weak and γ is approximately 0.05.\u0000 Below 35 bar, the bulk of the available data lies in the low CHF regime and appears to be nonlocal. For Peclet numbers less than 70,000, the two-parameter, nonlocal correlationqs/qc=d+A{1-exp[-B(Xo-Xi)]} correlates the low pressure data reasonably well. The parameters A and B are functions of pressure only. The variable qs = −λGXiD/4L i","PeriodicalId":324954,"journal":{"name":"Heat Transfer: Volume 3 — Experimental Studies in Multiphase Flow; Multiphase Flow in Porous Media; Experimental Multiphase Flows and Numerical Simulation of Two-Phase Flows; Fundamental Aspects of Experimental Methods","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132452435","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental Study of Flow Instability and CHF in a Natural Circulation System With Subcooled Boiling","authors":"R. Yang, Deyong Shi, Zhong Q. Lu, Rong Zheng, Yong Wang","doi":"10.1115/imece1996-0103","DOIUrl":"https://doi.org/10.1115/imece1996-0103","url":null,"abstract":"\u0000 Experimental study has been performed to investigate flow instability and critical heat flux (CHF) in a natural circulation system with subcooled boiling. In the experiments three kinds of heated sections were used. Freon-12 was used as the working medium. The experiments show that which one of the two phenomena, flow instability and CHF condition, may first occur in the system depends on not only the heat input power to the heated section and the parameters of the working medium, but also the construction of the heated section. The occurrence of the flow instability mainly depends on the total heat input power to the heated section and the CHF condition is mainly caused by the local heat flux of the heated section. In the experiments two kinds of flow instability, flow instability with high frequency and flow instability with low frequency, were found. But they all belong to density wave instability. The influence of the parameters of the working medium on the onset of the flow instability and CHF condition in the system were investigated. The stability boundaries were determined through the experiments. By means of dimensional analysis of integral equations, a common correlation describing the threshold condition of onset of the flow instability was obtained.","PeriodicalId":324954,"journal":{"name":"Heat Transfer: Volume 3 — Experimental Studies in Multiphase Flow; Multiphase Flow in Porous Media; Experimental Multiphase Flows and Numerical Simulation of Two-Phase Flows; Fundamental Aspects of Experimental Methods","volume":"93 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132836110","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A New Tomographic Image Reconstruction Method: Using a Hybrid Genetic Algorithm","authors":"D. P. Lyons, K. D. Kihm","doi":"10.1115/imece1996-0134","DOIUrl":"https://doi.org/10.1115/imece1996-0134","url":null,"abstract":"\u0000 A new tomographic image reconstruction method is introduced using a hybrid genetic algorithm. Both traditional genetic algorithms and a hybrid genetic algorithm associated with the concurrent simplex method are described and the merits of each are discussed. For the purposes of discussion, results from simple axisymmetric phantom test data are shown for the traditional and the hybrid genetic algorithm approaches. This new methodology shows the potential of alleviating difficulties with existing tomographic algorithms under the constraint of limited projection data.","PeriodicalId":324954,"journal":{"name":"Heat Transfer: Volume 3 — Experimental Studies in Multiphase Flow; Multiphase Flow in Porous Media; Experimental Multiphase Flows and Numerical Simulation of Two-Phase Flows; Fundamental Aspects of Experimental Methods","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131011313","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Boiling and Condensation Heat Transfer Correlations for Refrigerant-Oil Mixture Flows Inside Augmented Tubes","authors":"G. I. Usmani, T. S. Ravigururajan","doi":"10.1115/imece1996-0118","DOIUrl":"https://doi.org/10.1115/imece1996-0118","url":null,"abstract":"\u0000 General correlations to predict boiling and condensation heat-transfer-coefficient are proposed. Data analyzed include 134a condensation and evaporation of refrigerants such as R-22, R-12, R-113, and R-134a. Wide ranges of mass flux, heat flux, pressure, and vapor velocities are covered. Both low-fin tubes and the micro-fin tubes are considered. For boiling correlation more than 975 data points from four experimental studies are correlated and for condensation more than 525 data points from three experimental studies are correlated. The efforts resulted in the development of simple correlations for predicting the heat-transfer-coefficients during condensation and evaporation inside augmented tubes.\u0000 The results show that the boiling heat-transfer-coefficients decreased with increasing oil concentration and vapor quality, and increased with tube enhancement severity factor. Increasing mass flux, however, diminished the adverse effect of oil on the heat-transfer-coefficient. During condensation, the presence of oil diminished the heat-transfer performance of a micro-fin tube. The heat-transfer-coefficient decreased with increasing oil concentration used, and also with increasing severity factor.","PeriodicalId":324954,"journal":{"name":"Heat Transfer: Volume 3 — Experimental Studies in Multiphase Flow; Multiphase Flow in Porous Media; Experimental Multiphase Flows and Numerical Simulation of Two-Phase Flows; Fundamental Aspects of Experimental Methods","volume":"55 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114819388","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Water-Droplet Cooling Process in a Steam-Turbine Bypass Flow","authors":"R. Amano, G. R. Draxler, J. Gołembiewski","doi":"10.1115/imece1996-0093","DOIUrl":"https://doi.org/10.1115/imece1996-0093","url":null,"abstract":"\u0000 This paper presents a study of the numerical simulations of a steam flow and heat transfer behavior when subjected to a cooling water spray in the pipe downstream from a high-pressure turbine bypass valve. The structure of a cooling water spray injected into a steam flow was studied for the purpose of developing a physical model to investigate the dissipation and evaporation processes of the cooling water droplets in a high temperature, high turbulent steam flow passage. Heat transfer rates were calculated for a better understanding of the temperature variations in the entire system. A dispersed two-phase model was incorporated for the particle tracking of the droplets injected into the steam flow and the water evaporation process was observed. Further, this study was continued by installing a perforated plate in the pipe section downstream from the water cooling injections. The results of the calculations are quite reasonable, and show a physically sound state.","PeriodicalId":324954,"journal":{"name":"Heat Transfer: Volume 3 — Experimental Studies in Multiphase Flow; Multiphase Flow in Porous Media; Experimental Multiphase Flows and Numerical Simulation of Two-Phase Flows; Fundamental Aspects of Experimental Methods","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132814039","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}