The Calculation of Local Flow Properties in Two-Dimensional Furnaces

Khalil, Essam E.; Spalding, D. B.; Whitelaw, J. H.

doi:10.1016/b978-0-08-030937-8.50018-0

Cited by 10 publications

(17 citation statements)

References 10 publications

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“…Three time averaged velocity components in X, Y, and Z coordinate directions were obtained by solving the finite difference form of the governing equations using a "SIMPLE Numerical Algorithm" [Semi Implicit Method for Pressure Linked Equation] described earlier in the work [10][11][12][13]. The turbulence characteristics were represented by a modified k-e model to account for normal and shear stresses and near-wall functions.…”

Section: Numerical Methods 31 Mathematical Formulationmentioning

confidence: 99%

Three-Dimensional Flow Regimes and Heat Transfer Characteristics in Surgical Operating Theatre

Kameel

Khalil

2002

JHES

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Introduction Air conditioning implies the conditioning of airflow and heat transfer characteristics, temperatures, humidity, and dust level inside an enclosed space. The conditions to be maintained are dictated by the function of the conditioned space; therefore air conditioning embraces more than cooling or heating. Comfort air conditioning is defined as "the process of treating air to control simultaneously its temperature, humidity, cleanliness, and distribution to meet the comfort requirements of the occupants of the conditioned space.", ASHRAE [1]. Air conditioning therefore includes the regulation of velocity, thermal radiation, quality of air, and removal of foreign particles and vapors, Stoecker [2]. The human body is an amazingly adaptable organism as it can still function under extreme thermal conditions. Variations in climatic conditions, namely, temperature and humidity, however, often go beyond the normal limits of adaptability, and it becomes necessary to provide adjustable indoor conditions in order to maintain a healthy, comfortable environment, Stoecker [2]. Human comfort depends on the thermal characteristics of the surrounding environment and air velocity, also depends mainly, among previous factors, on the humidity. Thermal comfort is generally associated with a neutral body thermal sensation, Berglund [3], which in turn depends on thermal balance, metabolism and clothing. It is imperative that all attempts should be focussed on assuring the satisfaction of the required balance of rate of water loss from human body and surrounding air. Air movement in a room, therefore, becomes of vital importance to comfort, Khalil [4]. The healthcare requirements in residential applications differ basically from those applied to medical applications. No area of the hospital requires more careful control of the aseptic conditions of the environment than

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Section: Numerical Methods 31 Mathematical Formulationmentioning

confidence: 99%

Three-Dimensional Flow Regimes and Heat Transfer Characteristics in Surgical Operating Theatre

Kameel

Khalil

2002

JHES

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“…Mathematical models that are capable of predicting thermal performances of high-temperature furnaces from the fundamental laws of physics have been available for many years. Most furnace models are based on either computational fluid dynamic (CFD), so-called CFD models [39,40], or zone method of radiation analysis [41], so-called zone models. The prediction of fluid flow using CFD involves the simultaneous solution of the Navier-stokes equations for momentum conservation together with the equations for mass conservation in each of the relevant co-ordinate directions.…”

Section: Previous Work On Zone Modelling Of Reheating Furnacesmentioning

confidence: 99%

Modelling and simulation of steel reheating processes under oxy-fuel combustion conditions – Technical and environmental perspectives

Tan

Niska

et al. 2019

Energy

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This paper investigates the impact of flameless oxy-fuel combustion on the thermal performance of a pilot-scale steel reheating furnace. A comprehensive mathematical model, based on the zone method of radiation analysis, was developed, which takes into account the non-grey behaviour of the furnace atmosphere under oxy-fuel combustion conditions. The model was subsequently used to simulate the temperature profile of an instrumented slab used in the experiment. The results showed that the predicted slab temperature profile along the furnace is in good agreement with measurement. However the model over predicted the absolute slab temperatures due to the influence of formation of oxide scales on the slab surface, which was not taken into account in the current model. When compared to air-fuel combustion simulation, the results of oxy-fuel combustion also indicated a marked improvement in the furnace specific fuel consumption (approximately 16%). This was mainly due to the enhanced radiative properties of the furnace atmosphere and reduced exhaust energy losses as the result of less dilution effect from nitrogen. This resulted in reduction in the overall heating time by approximately 14 minutes. Furthermore, if the economics of carbon capture is taken into consideration, theoretically, the energy consumption per kilogram of CO 2 captured can be reduced from 3.5-4.2 MJ kg-1 to 0.96 MJ kg-1. In conclusion, the current studies support the view that oxy-fuel combustion retrofitting to reheating furnaces is a promising option, both from a technical and from an environmental point of view.

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“…• Combustion [Syred and Beer, 1974;Khalil, Spalding, and Whitelaw, 1975;Lilley, 1977;Huang, 1996;Qi, Gupta, and Lewis, 1997;Paschereit, Gutmark, and Weisenstein, 1999;Schluter, 2001;Li, 2004;Vanoverberghe, 2004;Duwig et al, 2005;Li and Gutmark, 2006;Paschereit, Flohr, and Gutmark, 2006;Nirmolo, 2007;Yongqiang, 2008;Valera-Medina, 2009;Stein, 2009],…”

Section: Axisymmetric Swirling (Vortex) Jetsmentioning

confidence: 99%

Swirling jets for the mitigation of hot spots and thermal stratification in the VHTR lower plenum.

Rodríguez¹

2011

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The literature indicates that a prismatic-core very high temperature reactor can experience thermal stratification and hot spot issues in the lower plenum (LP). This research hypothesizes that the complex thermalhydraulic phenomena in the LP requires a sophisticated computational fluid dynamics (CFD) code with state-of-the-art turbulence models and advanced swirling jet technology to mitigate the two issues. The primary research goals were to increase the heat transfer and mixing capacity of swirling jets, extend swirling jet theory, and to apply those advancements for the mitigation of the thermalhydraulic issues. First, it was demonstrated that the Fuego CFD code successfully modeled a set of key LP thermalhydraulic phenomena. Thereafter, a helicoid vortex swirl model was developed to investigate the impact of the swirl number (S) on mixing and heat transfer. The development of azimuthal and axial velocities that are solely functions of S permitted the analysis of the central recirculation zone's (CRZ) impact on the LP flow field. At this point, several characteristics were found in common between the helicoid vortex and other axisymmetric, Newtonian, incompressible vortices found in the literature. This observation resulted in a more fundamental understanding of how vortices behave, and which traits can be exploited for the purpose of maximizing heat transfer and mixing. Because the CRZ is a strong function of the azimuthal and axial velocities, shaping those velocity profiles had a substantial impact. Eventually, this led to the discovery that vortices may be expressed as alternating series that expand geometrically with odd exponents. This helped corroborate that the 15 axisymmetric vortices discussed in this research are part of a vortex family with seven common traits. This also led to the development of new vortices that are based on one or two series terms that satisfy the Navier-Stokes equations and conservation of mass. In addition, the impact of Reynolds number and swirl decay were explored in order to further quantify their impact. Finally, the above theories and modeling insights were applied towards a comprehensive set of LP calculations that showed that the swirling jets mitigated the entrainment and hot spot issues, while resulting in a reasonable pressure drop. Contents

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The Calculation of Local Flow Properties in Two-Dimensional Furnaces

Cited by 10 publications

References 10 publications

Three-Dimensional Flow Regimes and Heat Transfer Characteristics in Surgical Operating Theatre

Three-Dimensional Flow Regimes and Heat Transfer Characteristics in Surgical Operating Theatre

Modelling and simulation of steel reheating processes under oxy-fuel combustion conditions – Technical and environmental perspectives

Swirling jets for the mitigation of hot spots and thermal stratification in the VHTR lower plenum.

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