Sharif Digital Repository

Two different groups of radiative models are used to simulate a Midrex reformer. The modeling includes the furnace-side as well as the reactor-side equations. The simultaneous solution of governing equations provides the flue gas and tube wall temperature profiles. These are compared with literature and plant data. It was observed that the Flux model, applied in this work on the furnace of a bottom-fired reformer, shows a good agreement with observed plant data. The well-stirred model is still satisfactory but the long-furnace model is far away to merit an attention. © 2005 Elsevier Ltd. All rights reserved  

In this study, the influence of volumetric flow rate and inclination angle of air jet is evaluated on the performance of a Saccardo ventilation system in a straight rectangular tunnel in case of fire. Simultaneous effects of volumetric flow rate and inclination angle of jet exiting the Saccardo nozzle on the behavior of smoke plume is considered by studying the structure of velocity profile before the fire source. It is found that this factor has a remarkable influence on the behavior of smoke plume and therefore, on the temperatures experienced near the fire. Besides, the influence of tunnel slope on the performance of the Saccardo system to sweep the plume is investigated. It is shown that... 

In this paper, implosion of a micron-sized air bubble was studied numerically using OpenFoam software package. Then a parametric investigation on the flow physics of the problem was performed. The results show that as the initial pressure of the liquid increases, the pressure and the temperature inside the bubble increases such that in some cases, the temperature is as high as the one required for luminescence. Also, increasing the density and the temperature of the liquid solely, decreases the intensity of the collapse. © 2018  

General Circulation Models (GCMs) are advanced tools for impact assessment and climate change studies. Previous studies show that the performance of the GCMs in simulating climate variables varies significantly over different regions. This study intends to evaluate the performance of the Coupled Model Intercomparison Project phase 5 (CMIP5) GCMs in simulating temperature and precipitation over Iran. Simulations from 37 GCMs and observations from the Climatic Research Unit (CRU) were obtained for the period of 1901–2005. Six measures of performance including mean bias, root mean square error (RMSE), Nash-Sutcliffe efficiency (NSE), linear correlation coefficient (r), Kolmogorov-Smirnov... 

General Circulation Models (GCMs) are advanced tools for impact assessment and climate change studies. Previous studies show that the performance of the GCMs in simulating climate variables varies significantly over different regions. This study intends to evaluate the performance of the Coupled Model Intercomparison Project phase 5 (CMIP5) GCMs in simulating temperature and precipitation over Iran. Simulations from 37 GCMs and observations from the Climatic Research Unit (CRU) were obtained for the period of 1901–2005. Six measures of performance including mean bias, root mean square error (RMSE), Nash-Sutcliffe efficiency (NSE), linear correlation coefficient (r), Kolmogorov-Smirnov... 

Controlling the localized heat generation density and temperature profile of nanostructures exploiting perfect absorption of individual resonance modes is reported. The methodology is applied to spherically symmetric nanostructures using the T-matrix method. It is demonstrated that perfect modal splitting of the absorption power at desired wavelengths and individual excitation of the modes provide the ability to localize the generated heat at desired locations, and control the resulting temperature profile in multilayer core–shell structures. By knowing the thermal behavior of individual modes, it is shown that excitation of the perfect absorption modes at desired temperatures can result in... 

The design of a copper chloride laser is described, and the laser is optimised by studying the dependence of its output power on the buffer gas type. The voltage and current of the laser discharge at the optimum buffer gas pressure are measured. The influence of the diaphragm diameter on the specific output power is studied after optimisation of switch parameters. When an diaphragm producing the optimal temperature gradient in the laser gas-discharge tube, the record specific output power of 123 W L-1 is obtained without any admixtures. ©2007 Kvantovaya Elektronika and Turpion Ltd  

A high-order accurate implicit operator scheme is used to solve steady incompressible slip flow and heat transfer in 2D microchannels. The present methodology considers the solution of the Navier-Stokes equations using the artificial compressibility method with employing the Maxwell and Smoluchowski boundary conditions to model the slip flow and temperature jump on the walls in microchannels. Since the slip and temperature jump boundary conditions contain the derivatives of the velocity and temperature profiles, using the compact method the boundary conditions can be easily and accurately implemented. The computations are performed for a 2D microchannel and a 2D backward facing step in the... 

Here we introduce a phase-shifting digital holography-based method to determine the temperature profile around an irradiated (sub-)micron spherical bead. The method utilizes a Mach-Zehnder interferometer implemented into an open setup microscope. The results of irradiated gold spheres with diameter of 400 nm and also silver-coated micron-sized silica beads embedded in silicone oil are presented. We show that the applied method is able to accurately determine the surface temperature with accuracy of 1 °C. Our experimental results perfectly confirm the theoretical prediction of temperature profile around the irradiated bead  

Climate studies and effective environmental management require unbiased climate datasets. This study develops a new bias correction approach using a three-layer feedforward neural network to reduce the biases of climate variables (temperature and precipitation) over northern South America. Air and skin temperature, specific humidity, and net longwave and shortwave radiation are used as inputs to the network for bias correction of 6-hourly temperature. Inputs to the network for bias correction of monthly precipitation are precipitation at lag 0, 1, 2, and 3 months, and also the standard deviation of precipitation from 3 × 3 neighbors around the pixel of interest. The climate model data are... 

Over past decades, extensive research has been performed on the measurement of land subsidence as a result of compaction of aquifer. This paper describes results from a new field-monitoring system to evaluate changes in matric suction and temperature profiles in soil layers over an extended time period. The monitoring system used in this study consists of inserting dielectric sensors into a 105 m borehole, drilled in a site in Ardabil Plain, The monitoring results from the site were used to calibrate predictions from HYDRUS-1D. The physical and hydraulic properties of the soil materials in different layers were obtained through performing some soil characteristics and filter paper tests... 

This paper continues previous research performed by the authors on the modelling of dissimilar welded joints with varying clad thicknesses. This study aims to validate the use of a clad plate model as a replacement to the previous clad pipe model. To fulfill the hypothesis of the study, possible deformation or angular shrinkages occurring at weld joints have been simulated using a commercial finite element software. In parallel, angular shrinkages have been validated using the experimental data with the underlying concept of Gaussian transformation of plates into pipes. The welding of the two dissimilar materials has been carried out in-house with the aid of a Tungsten Arc weld with dynamic... 

We examine the effect of local thermal non-equilibrium on the steady state heat conduction in a porous layer in the presence of internal heat generation. A uniform source of heat is present in either the fluid or the solid phase. A two-temperature model is assumed and analytical solutions are presented for the resulting steady-state temperature profiles in a uniform porous slab. Attention is then focussed on deriving simple conditions which guarantee local thermal equilibrium. © Springer Science+Business Media, Inc. 2006  

In this investigation, a reactor model for prediction of the deactivation behavior of MTO's porous catalyst in a fixed bed reactor is developed. Effect of coking on molecular transport in the porous structure of SAPO-34 has been simulated using the percolation theory. Thermal effects of the reaction were considered in the model and the temperature profile of the gas stream in the reactor was predicted. The predicted loss in catalyst activity with time-on-stream was in very good agreement with the experimental data. The resulting coke deposition and gas temperature profiles along the length of reactor suggested a reaction front moving toward the outlet of the fixed bed reactor at the... 

Mixed-convection flow of nanofluids inside a vertical rectangular channel partially filled with open-cell metal foam and subject to a constant wall-heat flux was investigated experimentally and numerically. Al2O3-water nanofluids with different concentrations were prepared and their stability was examined using UV-Vis spectroscopy. Dynamic light scattering method was used to determine particle size distribution of the nanofluid feedstock. The outlet temperature and pressure drop were measured for different nanofluid flow rates (i.e., Reynolds number values). In the numerical section, a two-dimensional volume-averaged form of the governing equations was used. The velocity and temperature... 

A numerical analysis for determination of the stagnant and dispersion thermal conductivities in the Resin Transfer Molding (RTM) process is presented. A solution was obtained for the momentum and energy equations, which are used in this study and which represent the Brinkman- Forchheimer-extended Darcy model, and one-temperature energy equation. Subject to the appropriate boundary conditions, the governing equations are solved by the finite volume method on a collocated grid. In order to satisfy the pressure-velocity coupling in the solution, the SIMPLE algorithm was used and for determining the mass flux flowing past the cell faces, the Rhie-Chow interpolation was applied. Both constant and... 

In this article, mixed-convective heat transfer of nanofluids in a vertical channel partially filled with highly porous medium was studied. In the porous region, the Brinkman-Forchheimer extended Darcy model was used to describe the fluid flow pattern. Different viscous dissipation models were also applied to account for viscous heating. At the porous medium-fluid interface, interfacial coupling conditions for the fluid velocity and temperature were used to derive the analytical solution using a two-parameter perturbation method. The model used for the nanofluids incorporates the effects of Brownian motion and thermophoresis. With constant wall temperature, velocity and temperature profiles...