The Experts below are selected from a list of 204 Experts worldwide ranked by ideXlab platform
Liming Ruan - One of the best experts on this subject based on the ideXlab platform.
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application of hybrid spso sqp algorithm for simultaneous estimation of space dependent absorption coefficient and scattering coefficient fields in participating media
International Journal of Thermal Sciences, 2018Co-Authors: Hong Qi, Liming RuanAbstract:Abstract A hybrid stochastic particle swarm optimization (SPSO) and sequential quadratic programming (SQP) algorithm is proposed to estimate the space-dependent absorption coefficient (κa) and scattering coefficient (κs) fields simultaneously. The retrieval results of SQP algorithm are highly affected by the initial guess, and thus, SPSO is adopted to obtain the initial value of SQP because of its global search capability and lesser dependence on initial guess. The regularization term based on the generalized Gaussian Markov random field model is employed to overcome the ill-posed characteristic of the inverse problem. The inverse coupled Radiation-Conduction problem is solved in a one-dimensional participating medium with uniform refractive and graded refractive indices exposed to a pulse laser, respectively. All the results show that the separate space-dependent κa and κs fields can be estimated simultaneously and accurately from the coupled optical and thermal signals.
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improved social spider optimization algorithms for solving inverse Radiation and coupled Radiation Conduction heat transfer problems
International Communications in Heat and Mass Transfer, 2017Co-Authors: Hong Qi, Xiaoying Yu, Liming RuanAbstract:Abstract A novel bio-inspired swarm algorithm, social spider optimization (SSO), is introduced to solve the inverse transient Radiation and coupled Radiation–Conduction problems for the first time. Based on the original model, five improved SSO (ISSO) algorithms are developed to enhance search ability and convergence velocity. The sensitivity analysis of measured signals with respect to the physical parameters of the medium are described. After which, the SSO and ISSO algorithms are applied to solve the inverse estimation problems in a one-dimensional participating medium. Two cases concerns radiative transfer problems are investigated, in which the radiative source term, extinction coefficient, scattering albedo, and scattering symmetry factor are reconstructed. Furthermore, the coupled Radiation–Conduction heat transfer model is considered and the main parameters such as the Conduction–Radiation parameter, boundary emissivity, and scattering albedo are retrieved. All retrieval results show that SSO-based algorithms are robust and effective in solving inverse estimation problems even with measurement errors. Findings also show that the proposed ISSO algorithms are superior to the original SSO model in terms of computational accuracy and convergence velocity.
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solution of inverse Radiation Conduction problems using a kalman filter coupled with the recursive least square estimator
International Journal of Heat and Mass Transfer, 2017Co-Authors: Shuang Wen, Yatao Ren, Jianping Sun, Liming RuanAbstract:Abstract This paper presents a non–intrusive inverse heat transfer procedure for predicting the time–varying heat flux on the surface of semitransparent media. Inverse Radiation–Conduction problems were analyzed using a Kalman filter coupled with a recursive least–square estimator (KF–RLSE). Since its unique capability to make fast predictions, KF–RLSE can be easily integrated to existing real–time control systems of industrial facilities. The performance of KF–RLSE was examined thoroughly in a series of numerical simulations in two semitransparent materials (i.e. the glass with black coating and the ceramic of zirconium dioxide ZrO 2 ) to extract the time–varying surface heat flux on–line from the measured temperature history at boundary. Results showed that the proposed method can predict the unknown boundary flux with an acceptable error. The influence of different parameters on the accuracy and stability of the predicted heat flux was also investigated. Results indicated that the sensor location, process noise covariance and absorption coefficient exerted stronger effects on retrieval results compared with other parameters.
Mohsen Torabi - One of the best experts on this subject based on the ideXlab platform.
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heat transfer and thermodynamic performance of convective radiative cooling double layer walls with temperature dependent thermal conductivity and internal heat generation
Energy Conversion and Management, 2015Co-Authors: Mohsen Torabi, Kaili ZhangAbstract:Abstract Composite geometries have numerous applications in industry and scientific researches. This work investigates the temperature distribution, and local and total entropy generation rates within two-layer composite walls using conjugate convection and Radiation boundary conditions. Thermal conductivities of the materials of walls are assumed temperature-dependent. Temperature-dependent internal heat generations are also incorporated into the modeling. The differential transformation method (DTM) is used as an analytical technique to tackle the highly nonlinear system of ordinary differential equations. Thereafter, the local and total entropy generation rates are calculated using the DTM formulated temperature distribution. An exact analytical solution, for the temperature-independent model without Radiation effect, is also derived. The correctness and accuracy of the DTM solution are checked against the exact solution. After verification, effects of thermophysical parameters such as location of the interface, convection–Conduction parameters, Radiation–Conduction parameters, and internal heat generations, on the temperature distribution, and both local and total entropy generation rates are examined. To deliver the minimum total entropy generation rate, optimum values for some parameters are also found. Since composite walls are widely used in many fields, the abovementioned investigation is a beneficial tool for many engineering industries and scientific fields to minimize the entropy generation, which is the exergy destruction, of the system.
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accurate solution for convective radiative fin with variable thermal conductivity and nonlinear boundary condition by dtm
Arabian Journal for Science and Engineering, 2013Co-Authors: Mohsen Torabi, Hessameddin YaghoobiAbstract:In this paper, a convective–radiative straight fin with temperature-dependent thermal conductivity is analyzed. The tip of the fin is assumed to lose heat by convection and Radiation to the same sink. The calculations are carried out using the differential transformation method (DTM) which is a semi-numerical-analytical solution technique that can be applied to various types of differential equations. The principle of differential transformation is briefly introduced, and then applied for the afore-mentioned equations. The current results are then compared with previously obtained results using the variational iteration method, the homotopy perturbation method, the homotopy analysis method, the double optimal linearization method and numerical solution to verify the accuracy of the proposed method. The findings reveal that the DTM can achieve more suitable than other methods in predicting the solution of such problems. After this verification, we analyze fin efficiency and the effects of some physically applicable parameters in this problem such as thermal conductivity, the convection–Conduction parameter, the Radiation–Conduction parameter, convection sink temperature and Radiation sink temperature.
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convective radiative fins with simultaneous variation of thermal conductivity heat transfer coefficient and surface emissivity with temperature
Heat Transfer Research, 2012Co-Authors: A Aziz, Mohsen TorabiAbstract:This paper is a numerical study of thermal performance of a convective-radiative fin with simultaneous variation of thermal conductivity, heat transfer coefficient, and surface emissivity with temperature. The convective heat transfer is assumed to be a power function of the local temperature between the fin and the ambient which allows simulation of different convection mechanisms such as natural convection (laminar and turbulent), boiling, etc. The thermal conductivity and the surface emissivity are treated as linear functions of the local temperature between the fin and the ambient which provide a satisfactory representation of the thermal property variations of most fin materials. The thermal performance is governed by seven parameters, namely, convection–Conduction parameter Nc, Radiation–Conduction parameter Nr, thermal conductivity parameter A, emissivity parameter B, the exponent n associated with convective heat transfer coefficient, and the two temperature ratios, θa and θs, that characterize the temperatures of convection and Radiation sinks. The effect of these parameters on the temperature distribution and fin heat transfer rate are illustrated and the results interpreted in physical terms. Compared with the constant properties model, the fin heat transfer rate can be underestimated or overestimated considerably depending on the values of the governing parameters. © 2011 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library (wileyonlinelibrary.com/journal/htj). DOI 10.1002/htj.20408
Yatao Ren - One of the best experts on this subject based on the ideXlab platform.
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simultaneous estimation of internal temperature field and boundary time dependent heat flux in absorbing and scattering media using the unscented kalman smoothing technique
Journal of Quantitative Spectroscopy & Radiative Transfer, 2020Co-Authors: Shuang Wen, Yatao Ren, Juqi ZhangAbstract:Abstract Based on the future measured temperature, the Rauch-Tung-Striebel smoothing technique coupled with unscented Kalman filter is introduced to resolve the nonlinear inverse Radiation-Conduction heat transfer problem, which is nonlinear because of specific heat and thermal conductivity with temperature and existence of the radiative heat transfer. For the direct process, the finite volume method is applied to calculate the energy equation and radiative transfer equation is computed by the discrete ordinate method. Based on the measurement temperature signals of the right surface, the left surface time-dependent heat flux and interior temperature in absorbing and scattering medium are retrieved in near real time by using the proposed method. The different number of the future measured temperature, measurement noise, and process noise covariance are applied to examine the feasibility and reliability of the present algorithm. All retrieval results show that the Rauch-Tung-Striebel smoothing technique coupled with unscented Kalman filter is accurate and stable. Compared to the unscented Kalman filter, the accuracy of the retrieval temperature distribution is improved significantly, the deviation and oscillation of the retrieval time-dependent heat flux are also decreased substantially.
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efficient and robust prediction of internal temperature distribution and boundary heat flux in participating media by using the kalman smoothing technique
International Journal of Heat and Mass Transfer, 2020Co-Authors: Shuang Wen, Yatao Ren, Zhitian Niu, Linyang WeiAbstract:Abstract The Kalman smoothing (KS) technique, which is consisted of the Kalman filtering and Rauch-Tung-Striebel smoothing technique, is introduced to resolve the inverse Radiation-Conduction heat transfer problem by using the future temperature measurement information. For the forward problem, the discrete ordinate method is employed to solve the radiative transfer equation and the energy equation is resolved by using the finite volume method. The boundary time-dependent heat flux and internal temperature filed in participating media are retrieved in near real time from measurement temperature on the right surface. Different forms of time-dependent heat flux are imposed on the left surface to examine the performance of the proposed algorithm. All the reconstruction results indicate that the KS technique is effective and robust for resolving the retrieval of the boundary time-dependent heat flux and internal temperature fields in near real time. The effect of different parameters on the accuracy and stability of the reconstruction results, including the future temperature information, sampling interval, measurement noise covariance, initial state error, and initial state error covariance, are analyzed in detail. Compared with the KF technique, the reconstruction accuracy of KS technique can be improved obviously. Meanwhile, the time delay and oscillation of reconstructed heat flux are reduced significantly and the deviation of the retrieval temperature is also decreased greatly.
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solution of inverse Radiation Conduction problems using a kalman filter coupled with the recursive least square estimator
International Journal of Heat and Mass Transfer, 2017Co-Authors: Shuang Wen, Yatao Ren, Jianping Sun, Liming RuanAbstract:Abstract This paper presents a non–intrusive inverse heat transfer procedure for predicting the time–varying heat flux on the surface of semitransparent media. Inverse Radiation–Conduction problems were analyzed using a Kalman filter coupled with a recursive least–square estimator (KF–RLSE). Since its unique capability to make fast predictions, KF–RLSE can be easily integrated to existing real–time control systems of industrial facilities. The performance of KF–RLSE was examined thoroughly in a series of numerical simulations in two semitransparent materials (i.e. the glass with black coating and the ceramic of zirconium dioxide ZrO 2 ) to extract the time–varying surface heat flux on–line from the measured temperature history at boundary. Results showed that the proposed method can predict the unknown boundary flux with an acceptable error. The influence of different parameters on the accuracy and stability of the predicted heat flux was also investigated. Results indicated that the sensor location, process noise covariance and absorption coefficient exerted stronger effects on retrieval results compared with other parameters.
A Aziz - One of the best experts on this subject based on the ideXlab platform.
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transient heat transfer in a heat generating fin with Radiation and convection with temperature dependent heat transfer coefficient
Heat Transfer Research, 2012Co-Authors: Waqar A Khan, A AzizAbstract:The transient heat transfer in a heat-generating fin with simultaneous surface convection and Radiation is studied numerically for a step change in base temperature. The convection heat transfer coefficient is assumed to be a power law function of the local temperature difference between the fin and its surrounding fluid. The values of the power exponent n are chosen to include simulation of natural convection (laminar and turbulent) and nucleate boiling among other convective heat transfer modes. The fin is assumed to have uniform internal heat generation. The transient response of the fin depends on the convection-Conduction parameter, Radiation-Conduction parameter, heat generation parameter, power exponent, and the dimensionless sink temperature. The instantaneous heat transfer characteristics such as the base heat transfer, surface heat loss, and energy stored are reported for a range of values of these parameters. When the internal heat generation exceeds a threshold the fin acts as a heat sink instead of a heat source. © 2012 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library (wileyonlinelibrary.com/journal/htj). DOI 10.1002/htj.21012
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convective radiative fins with simultaneous variation of thermal conductivity heat transfer coefficient and surface emissivity with temperature
Heat Transfer Research, 2012Co-Authors: A Aziz, Mohsen TorabiAbstract:This paper is a numerical study of thermal performance of a convective-radiative fin with simultaneous variation of thermal conductivity, heat transfer coefficient, and surface emissivity with temperature. The convective heat transfer is assumed to be a power function of the local temperature between the fin and the ambient which allows simulation of different convection mechanisms such as natural convection (laminar and turbulent), boiling, etc. The thermal conductivity and the surface emissivity are treated as linear functions of the local temperature between the fin and the ambient which provide a satisfactory representation of the thermal property variations of most fin materials. The thermal performance is governed by seven parameters, namely, convection–Conduction parameter Nc, Radiation–Conduction parameter Nr, thermal conductivity parameter A, emissivity parameter B, the exponent n associated with convective heat transfer coefficient, and the two temperature ratios, θa and θs, that characterize the temperatures of convection and Radiation sinks. The effect of these parameters on the temperature distribution and fin heat transfer rate are illustrated and the results interpreted in physical terms. Compared with the constant properties model, the fin heat transfer rate can be underestimated or overestimated considerably depending on the values of the governing parameters. © 2011 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library (wileyonlinelibrary.com/journal/htj). DOI 10.1002/htj.20408
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convection Radiation from a continuously moving variable thermal conductivity sheet or rod undergoing thermal processing
International Journal of Thermal Sciences, 2011Co-Authors: A Aziz, Robert J LopezAbstract:Abstract A numerical study of the heat transfer process in a continuously moving sheet or rod of variable thermal conductivity that loses heat by simultaneous convection and Radiation is reported. The process is governed by five dimensionless parameters, namely Peclet number Pe, thermal conductivity parameter a, convection-Conduction parameter Nc, Radiation-Conduction parameter Nr, and sink-to-base temperature-ratio, θa. The effects of these parameters on the temperature distribution, base heat Conduction rate, advection and surface heat loss are illustrated and explained. The dimensionless length parameter, L∗, that the material must traverse to cool to within one percent of the sink temperature is determined for various combinations of the five parameters. This information gives the designer the fabrication time if the material is moved at a certain speed or it gives the speed if the processing of the material is to be completed in a fixed period of time.
Aldo Steinfeld - One of the best experts on this subject based on the ideXlab platform.
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heat transfer and geometrical analysis of thermoelectric converters driven by concentrated solar Radiation
Materials, 2010Co-Authors: Clemens Suter, P Tomes, Anke Weidenkaff, Aldo SteinfeldAbstract:A heat transfer model that couples Radiation/Conduction/convection heat transfer with electrical potential distribution is developed for a thermoelectric converter (TEC) subjected to concentrated solar Radiation. The 4-leg TEC module consists of two pairs of p- type La1.98Sr0.02CuO4 and n-type CaMn0.98Nb0.02O3 legs that are sandwiched between two ceramic Al2O3 hot/cold plates and connected electrically in series and thermally in parallel. The governing equations for heat transfer and electrical potential are formulated, discretized and solved numerically by applying the finite volume (FV) method. The model is validated in terms of experimentally measured temperatures and voltages/power using a set of TEC demonstrator modules, subjected to a peak radiative flux intensity of 300 suns. The heat transfer model is then applied to examine the effect of the geometrical parameters (e.g. length/width of legs) on the solar-to-electricity energy conversion efficiency.
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an ablation model for the thermal decomposition of porous zinc oxide layer heated by concentrated solar Radiation
International Journal of Heat and Mass Transfer, 2009Co-Authors: Leonid A Dombrovsky, Lothar O Schunk, Wojciech Lipinski, Aldo SteinfeldAbstract:Thermal decomposition of porous ZnO under high-flux solar irRadiation is considered. The process is well described by a transient ablation model that couples Radiation, Conduction, and convection heat transfer to an Arrhenius-type kinetic rate law with a pre-exponential factor dependent on the porosity, grain/pore size, and convective removal of the reaction products Zn(g) and O2. Main model parameters are determined by comparing numerical and experimental results.
