Quantification of the impact of paleoclimates on the deep heat flux of the Paris Basin

Abstract Steelmaking is an energy-intensive process. Thus, energy efficiency is highly important. Several stages of steelmaking involve combustion processes. One of the most energy-consuming processes in steelmaking is the slab reheating process in a reheat furnace (RF). The energy released by fuel combustion is used to heat steel slabs to their proper hot-rolling temperature. The steel slabs move through the reheat furnace passing the three stages of heating called: Preheating Zone (PZ), Heating Zone (HZ), and Soaking Zone (SZ) to finally leave the discharge door at a rolling temperature of 2375 °F. One way to improve a reheat furnace’s fuel consumption is by implementing oxygen-enriched combustion. This study investigates the implementation of oxygen-enriched combustion in a pusher-type reheat furnace. The increment of oxygen in the combustion process allows for increasing the furnace gas temperature. Consequently, the oxygen enrichment approach allows for the reduction of fuel injection. The principal goal of this investigation is to model the combustion-based on oxygen-enrichment and develop parametric studies of fuel injection rates. The different simulations aim to match the slab heat flux profile of the industrial reheat furnace pusher-type. Computational fluid dynamics are used to generate the slab heat flux distribution. To reach more uniform slab heating, oxygen and fuel ports were alternated. Also, injection angles were modified to optimize slab heating and avoid the impact of hot spots. Thermocouple readings of the industrial reheat furnace are compared to simulation results. The results determined that 40–45% fuel reduction can be achieved.

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The impact of broadleaved woodland on water resources in lowland UK: II. Evaporation estimates from sensible heat flux measurements over beech woodland and grass on chalk sites in Hampshire

Hydrology and Earth System Sciences ◽

10.5194/hess-9-607-2005 ◽

2005 ◽

Vol 9 (6) ◽

pp. 607-613 ◽

Cited By ~ 12

Author(s):

J. Roberts ◽

P. Rosier ◽

D. M. Smith

Keyword(s):

Heat Flux ◽

Energy Balance ◽

Excellent Agreement ◽

Sensible Heat Flux ◽

Late Summer ◽

Eddy Correlation ◽

Sensible Heat ◽

Flux Measurements ◽

Shallow Soils ◽

The Impact

Abstract. The impact on recharge to the Chalk aquifer of substitution of broadleaved woodland for pasture is a matter of concern in the UK. Hence, measurements of energy balance components were made above beech woodland and above pasture, both growing on shallow soils over chalk in Hampshire. Latent heat flux (evaporation) was calculated as the residual from these measurements of energy balances in which sensible heat flux was measured with an eddy correlation instrument that determined fast response vertical wind speeds and associated temperature changes. Assessment of wind turbulence statistics confirmed that the eddy correlation device performed satisfactorily in both wet and dry conditions. There was excellent agreement between forest transpiration measurements made by eddy correlation and stand level tree transpiration measured with sap flow devices. Over the period of the measurements, from March 1999 to late summer 2000, changes in soil water content were small and grassland evaporation and transpiration estimated from energy balance-eddy flux measurements were in excellent agreement with Penman estimates of potential evaporation. Over the 18-month measurement period, the cumulative difference between broadleaved woodland and grassland was small but evaporation from the grassland was 3% higher than that from the woodland. In the springs of 1999 and 2000, evaporation from the grassland was greater than that from the woodland. However, following leaf emergence in the woodland, the difference in cumulative evaporation diminished until the following spring.

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Seasonal Surface Air Temperature and Precipitation in the FSU Climate Model Coupled to the CLM2

Journal of Climate ◽

10.1175/jcli3470.1 ◽

2005 ◽

Vol 18 (16) ◽

pp. 3217-3228 ◽

Cited By ~ 16

Author(s):

D. W. Shin ◽

S. Cocke ◽

T. E. LaRow ◽

James J. O’Brien

Keyword(s):

Heat Flux ◽

Air Temperature ◽

Climate Model ◽

Initial Conditions ◽

Sensible Heat Flux ◽

Surface Air Temperature ◽

Community Land Model ◽

Temperature And Precipitation ◽

The Impact ◽

Convective Scheme

Abstract The current Florida State University (FSU) climate model is upgraded by coupling the National Center for Atmospheric Research (NCAR) Community Land Model Version 2 (CLM2) as its land component in order to make a better simulation of surface air temperature and precipitation on the seasonal time scale, which is important for crop model application. Climatological and seasonal simulations with the FSU climate model coupled to the CLM2 (hereafter FSUCLM) are compared to those of the control (the FSU model with the original simple land surface treatment). The current version of the FSU model is known to have a cold bias in the temperature field and a wet bias in precipitation. The implementation of FSUCLM has reduced or eliminated this bias due to reduced latent heat flux and increased sensible heat flux. The role of the land model in seasonal simulations is shown to be more important during summertime than wintertime. An additional experiment that assimilates atmospheric forcings produces improved land-model initial conditions, which in turn reduces the biases further. The impact of various deep convective parameterizations is examined as well to further assess model performance. The land scheme plays a more important role than the convective scheme in simulations of surface air temperature. However, each convective scheme shows its own advantage over different geophysical locations in precipitation simulations.

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Uncertainty Quantification of Thermocouple Air Temperature Measurement in Highly Radiative Environment: Application to Turbofan Engine Compartment

Volume 5A: Heat Transfer ◽

10.1115/gt2016-57938 ◽

2016 ◽

Cited By ~ 1

Author(s):

Y. Sommerer ◽

V. Drouin ◽

X. Nicolas ◽

B. Trouette

Keyword(s):

Heat Flux ◽

Temperature Measurement ◽

Air Temperature ◽

Data Bank ◽

Heat Shield ◽

Engine Compartment ◽

Heat Shields ◽

Air Speed ◽

Thermocouple Temperature ◽

The Impact

This paper focuses on thermocouple air temperature measurement uncertainty due to the radiative fluxes present in the engine compartment where engine case skin temperature can exceed 900 K. To really measure air temperature, the convective heat flux in the thermocouple bead must be predominant. This is why heat shields are used in order to reduce the radiative heat flux on the bead. However, in engine compartment, the heat shield orientation must be optimized since numerous hot walls surround the thermocouple. In order to evaluate the impact of badly oriented heat shields and to provide a data bank for numerical simulation validations, a heated wind tunnel has been used. It has been shown that the uncertainty on the thermocouple temperature can reach dozens of degrees depending on the air speed and the heat shield orientation. Furthermore a specific 3D thermocouple model has been build and validated by comparison with the lab measurements. Then this thermocouple 3D model has been integrated in the whole engine compartment aero-thermal model in order to quantify the uncertainty of the thermocouple air temperature measurement in the real engine environment.

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Experimental Study of the Endwall Heat Transfer of a Transonic Nozzle Guide Vane With Upstream Jet Purge Cooling: Part 1 — Effect of Density Ratio

Volume 7B: Heat Transfer ◽

10.1115/gt2020-14814 ◽

2020 ◽

Author(s):

Shuo Mao ◽

Ridge A. Sibold ◽

Stephen Lash ◽

Wing F. Ng ◽

Hongzhou Xu ◽

...

Keyword(s):

Heat Transfer ◽

Heat Flux ◽

Mass Flux ◽

Guide Vane ◽

Density Ratio ◽

Momentum Ratio ◽

Blowing Ratio ◽

Nozzle Guide Vane ◽

Nozzle Guide ◽

The Impact

Abstract Nozzle guide vane platforms often employ complex cooling schemes to mitigate ever-increasing thermal loads on endwall. Understanding the impact of advanced cooling schemes amid the highly complex three-dimensional secondary flow is vital to engine efficiency and durability. This study analyzes and describes the effect of coolant to mainstream blowing ratio, momentum ratio and density ratio for a typical axisymmetric converging nozzle guide vane platform with an upstream doublet staggered, steep-injection, cylindrical hole jet purge cooling scheme. Nominal flow conditions were engine representative and as follows: Maexit = 0.85, Reexit/Cax = 1.5 × 106 and an inlet large-scale freestream turbulence intensity of 16%. Two blowing ratios were investigated, each corresponding to upper and lower engine extrema at M = 3.5 and 2.5, respectively. For each blowing ratio, the coolant to mainstream density ratio was varied between DR = 1.2, representing typical experimental neglect of coolant density, and DR = 1.95, representative of typical engine conditions. An optimal coolant momentum ratio between = 6.3 and 10.2 is identified for in-passage film effectiveness and net heat flux reduction, at which the coolant suppresses and overcomes secondary flows but imparts minimal turbulence and remains attached to endwall. Progression beyond this point leads to cooling effectiveness degradation and increased endwall heat flux. Endwall heat transfer does not scale well with one single parameter; increasing with increasing mass flux for the low density case but decreasing with increasing mass flux of high density coolant. From the results gathered, both coolant to mainstream density ratio and blowing ratio should be considered for accurate testing, analysis and prediction of purge jet cooling scheme performance.

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Heat transport in turbulent electro-hydrodynamics

10.5194/egusphere-egu21-3979 ◽

2021 ◽

Author(s):

Florian Zaussinger ◽

Peter Haun ◽

Peter Szabo ◽

Christoph Egbers

Keyword(s):

Heat Flux ◽

Spherical Shell ◽

Rectangular Cavity ◽

Microwave Drying ◽

Dielectric Heating ◽

Layer Formation ◽

Dielectrophoretic Force ◽

Volumetric Heating ◽

Thermal Buoyancy ◽

The Impact

<p>Electro-hydrodynamics (EHD) plays an important role in many industrial applications. Ink-jet printers, microwave drying facilities, and lab-on-a-chip devices utilize dielectric properties of the working fluids and their manipulation without moving parts. Another application is found in heat exchangers, where the dielectrophoretic force is used to increase heat transfer due to thermal buoyancy. In particular, the dielectrophoretic force has great advantages in low- and micro-gravity conditions since the force can be used to mimic a gravitational force field. Hence, convection in a rectangular cavity induced by EHD is a model system comparable to Rayleigh-Benard (RB) convection. However, the electric-driven buoyancy term and dielectric heating make the system more complex. The direction of the triggering dielectrophoretic force depends mainly on the temperature gradient which can be used to manipulate the heat flux or the entire structure of the convective flow. Layer formation, comparable to double-diffusive convection, and convective overshooting are two representative cases which can be established by EHD, too. We will present first results of turbulent convection induced by EHD in the rectangular cavity and the impact of volumetric heating. For this purpose, the Boussinesq approximation, as well as compressible models for EHD, are tested also for applicability in geophysical relevant regimes. This is a crucial point as the limitations by incompressible modeling are not well-understood for EHD. The main focus of the study is the analysis of the heat flux as a function of the thermo-electric feedback and the dielectric heating rate. Convective overshooting and layer formation are examined closely. Results of this study are used to estimate transport properties and time scales. Applications using EHD are the GeoFlow and AtmoFlow experiments. The GeoFlow experiment was conducted several years on the International Space Station and gained deep insight into EHD driven convection in the spherical shell geometry. The AtmoFlow experiment is under construction and is planned for operations on the ISS in 2024. This experiment is designed to study atmospheric like flows in the spherical shell.</p>

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Nanoparticle aggregation kinematics on the quadratic convective magnetohydrodynamic flow of nanomaterial past an inclined flat plate with sensitivity analysis

Proceedings of the Institution of Mechanical Engineers Part E Journal of Process Mechanical Engineering ◽

10.1177/09544089211056235 ◽

2021 ◽

pp. 095440892110562

Author(s):

AS Sabu ◽

Joby Mackolil ◽

B Mahanthesh ◽

Alphonsa Mathew

Keyword(s):

Heat Transfer ◽

Heat Flux ◽

Sensitivity Analysis ◽

Heat Transfer Coefficient ◽

Heat Source ◽

Transfer Coefficient ◽

Flat Plate ◽

Inclined Plate ◽

The Impact ◽

The Heat Transfer Coefficient

The study focuses on the aggregation kinematics in the quadratic convective magneto-hydrodynamics of ethylene glycol-titania ([Formula: see text]) nanofluid flowing through an inclined flat plate. The modified Krieger-Dougherty and Maxwell-Bruggeman models are used for the effective viscosity and thermal conductivity to account for the aggregation aspect. The effects of an exponential space-dependent heat source and thermal radiation are incorporated. The impact of pertinent parameters on the heat transfer coefficient is explored by using the Response Surface Methodology and Sensitivity Analysis. The effects of several parameters on the skin friction and heat transfer coefficient at the plate are displayed via surface graphs. The velocity and thermal profiles are compared for two physical scenarios: flow over a vertical plate and flow over an inclined plate. The nonlinear problem is solved using the Runge–Kutta-based shooting technique. It was found that the velocity profile significantly decreased as the inclination of the plate increased on the other hand the temperature profile improved. The heat transfer coefficient decreased due to the increase in the Hartmann number. The exponential heat source has a decreasing effect on the heat flux and the angle of inclination is more sensitive to the heat transfer coefficient than other variables. Further, when radiation is incremented, the sensitivity of the heat flux toward the inclination angle augments at the rate 0.5094% and the sensitivity toward the exponential heat source augments at the rate 0.0925%. In addition, 41.1388% decrement in wall shear stress is observed when the plate inclination is incremented from [Formula: see text] to [Formula: see text].

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Impact of Second-Order Slip and Double Stratification Coatings on 3D MHD Williamson Nanofluid Flow with Cattaneo–Christov Heat Flux

Coatings ◽

10.3390/coatings9120849 ◽

2019 ◽

Vol 9 (12) ◽

pp. 849 ◽

Cited By ~ 8

Author(s):

Muhammad Ramzan ◽

Asma Liaquet ◽

Seifedine Kadry ◽

Sungil Yu ◽

Yunyoung Nam ◽

...

Keyword(s):

Heat Flux ◽

Three Dimensional ◽

Equation System ◽

Second Order ◽

Double Stratification ◽

Nanofluid Flow ◽

Analysis Technique ◽

Homotopy Analysis ◽

Opposite Behavior ◽

The Impact

The present research examines the impact of second-order slip with thermal and solutal stratification coatings on three-dimensional (3D) Williamson nanofluid flow past a bidirectional stretched surface and envisages it analytically. The novelty of the analysis is strengthened by Cattaneo–Christov (CC) heat flux accompanying varying thermal conductivity. The appropriate set of transformations is implemented to get a differential equation system with high nonlinearity. The structure is addressed via the homotopy analysis technique. The authenticity of the presented model is verified by creating a comparison with the limited published results and finding harmony between the two. The impacts of miscellaneous arising parameters are deliberated through graphical structures. Some useful tabulated values of arising parameters versus physical quantities are also discussed here. It is observed that velocity components exhibit an opposite trend with respect to the stretching ratio parameter. Moreover, the Brownian motion parameter shows the opposite behavior versus temperature and concentration distributions.

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