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1.
The presence of thermocouples inside a heat-conducting body will distort the temperature field in the body and may lead to significant bias in the temperature measurement. If temperature histories obtained from thermocouples are used in the inverse heat conduction problem (IHCP), errors are propagated into the IHCP results. The bias in the thermocouple measurements can be removed through use of appropriate detailed thermocouple models to account for the dynamics of the sensor measurement. The results of these models can be used to generate correction kernels to eliminate bias in the thermocouple reading, or can be applied as sensitivity coefficients in the IHCP directly. Three-dimensional and axisymmetric models are compared and contrasted and a simple sensitivity study is conducted to evaluate the significance of thermal property selection on the temperature correction and subsequent heat flux estimation. In this paper, a high-fidelity thermocouple model is used to account for thermocouple bias in an experiment to measure heat fluxes from solidifying aluminum to a sand mold. Correction kernels are obtained that are used to demonstrate the magnitude of the temperature measurement bias created by the thermocouples. The corrected temperatures are used in the IHCP to compute the surface heat flux. A comparison to IHCP results using uncorrected temperatures shows the impact of the bias correction on the computed heat fluxes.  相似文献   

2.

This paper investigates the dynamic thermoelastic response of a heated thin composite plate. The plate is composed of a dominant matrix domain and an insert domain. A step-function heat source is generated within the matrix domain, causing the heating of the whole plate. The dual-phase-lag heat conduction model is used to determine the thermal behavior of the plate in the form of the spatial and time variations of the temperatures in both domains. The temperature of the matrix is used to evaluate the thermoelastic behavior of the plate in the form of the induced displacements and thermal stresses. The Laplace transformation technique combined with the Rieman-sum method is used to calculate the temperatures. The finite difference method is used to solve the governing equation of plate deflection and then calculate the thermal stresses. The resulting thermal stresses are found to be compressive and follow the same behavior as that of the temperature.  相似文献   

3.
In this work, the prefiltering of the sensor data is taken into consideration when solving an inverse heat conduction problem. The temperature data obtained from each sensor is considered as a discrete signal, and discrete wavelet transform in a multi-resolution filter bank structure is utilized for the signal analysis, after which wavelet denoising algorithm is applied to remove noise from data signal. Subsequently, noisy and denoised temperatures are separately used as input data to an inverse heat conduction problem for comparison. The inverse heat conduction problem considered in this article is an inverse volumetric heat source problem, and it is solved using the conjugate gradient method along with the associated adjoint problem used to obtain the gradient of the objective function. Three sets of results in two case studies are compared (i.e., the result obtained from non-noisy data, noisy data, and denoised data). In the case of noisy data, iterative regularization is used to regularize the solution. The root mean square error of the estimated heat source from denoised data is reduced approximately by a factor of seven to nine as compared to those obtained from noisy data.  相似文献   

4.
In this article we consider a model describing the temperature profile in a longitudinal fin with rectangular, concave, triangular, and convex parabolic profiles. Both thermal conductivity and the heat transfer coefficient are assumed to be temperature‐dependent, and given by a linear function and by power laws, respectively. In addition, the effects of the thermal conductivity gradient have been investigated. Optimal homotopy analysis method (OHAM) is employed to analyze the problem. The effects of the physical applicable parameters such as thermo‐geometric fin, thermal conductivity, and heat transfer mode are analyzed. The OHAM solutions are obtained and validity of obtained solutions is verified by the Runge–Kutta fourth‐order method and numerical simulation. A very good agreement is found between analytical and numerical results. Also for investigation of lateral effects on the accuracy of results, numerical simulation (by Ansis software) is compared with the homotopy analysis method (HAM) and numerical solution (by Runge–Kutta) of the energy balance equation. © 2013 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library ( wileyonlinelibrary.com/journal/htj ). DOI 10.1002/htj.21104  相似文献   

5.
A solution method using exponential basis functions (EBFs) is proposed for transient one-/two-dimensional non-Fourier heat conduction problems having particular application in bio-heat fields. A summation of EBFs satisfying the governing differential equation is considered in time and space. The presented method uses a noniterative algorithm for the solution of direct/inverse problems. It is demonstrated that the use of extra EBFs in the form of enrichment functions significantly improves the results when some jumps are seen in the input data. Four numerical examples, including bio-heat conduction problems, are provided to investigate the accuracy and performance of the method presented.  相似文献   

6.
板式石蜡储热器传热的数值模拟   总被引:1,自引:0,他引:1  
在相变储热器中采用强化传热技术,克服相变材料的低导热性能,是目前国内外研究的热点。应用FLUENT软件数值模拟了翅片强化板式石蜡储热器的凝固传热过程,得到随时间变化的相界面位置、总凝固时间、壁面热流、翅片温度分布等,并进一步分析了翅片对不同长宽比叫的储热器的强化传热效果。模拟结果表明,只有当ω≥1时,翅片才能对储热器起到明显的强化传热作用,研究结果可为相变储热器的优化设计提供可靠的依据。  相似文献   

7.
翅柱复合型冷却器表面传热性能的数值研究   总被引:1,自引:0,他引:1  
提出一种用于油液冷却的新型翅柱复合型冷却器,并应用SIMPLE算法对于其二维简化模型在不同工况下的表面传热及流动阻力进行数值模拟。将模拟结果与试验和经验关联式相比较,吻合情况良好,表明此算法和所简化的模型是合理的。根据数值模拟结果研究这种传热表面的传热机理,分析翅柱位置及几何参数对流动与传热的影响,对该新型翅片的推广及优化设计有较大帮助。  相似文献   

8.
An analysis was carried out to study the efficiency of a straight rectangular fin with a uniform cross-section area when subjected to simultaneous heat and mass transfer mechanisms. The temperature and humidity ratio differences are the driving forces for the heat and mass transfer, respectively. Numerical solutions are obtained for the temperature distribution over the fin surface when the fin surface is dry, fully wet, and partially wet. The psychrometric correlation of an air-water vapor mixture was used to simulate the relation between the temperature and humidity ratio instead of the linear approximate correlations used in the literature. The effect of atmospheric pressure on the fin efficiency was also studied, in addition to fin optimum thickness for specific operating conditions. The numerical solution was compared with those of previous studies in order to find if the linear model in the published analytical results are near to the real situation. It is found that the linear model for the relation between the humidity ratio and the temperature used by Wu and Bong is a reasonable engineering approximation for small values of the fin parameter and at low relative humidities.  相似文献   

9.
The fast multipole method (FMM) is an effective technique to reduce the computational cost in solving large-scale problems. In this article, a new fast multipole hybrid boundary-node method (FM-HBNM) is presented to solve three-dimensional heat conduction problems. In the new FM-HBNM, a diagonal form for translation operators is used and the computational cost of the multipole to local (M2L) translation is further reduced. Formulations for the new FM-HBNM are derived. The computational costs for the original and new FM-HBNM are estimated. The numerical results show that a speed-up about 2–3 times can be achieved by the new FM-HBNM.  相似文献   

10.
This paper aims to estimate a location- and time-dependent high-magnitude heat flux in a heat conduction problem. The heat flux is applied on a small region of a surface of a flat plate, while transient temperature measurements are taken on the opposite surface. This inverse problem is solved using the Kalman filter and a reduced forward model, obtained by simplifications of a three-dimensional and nonlinear heat conduction problem. To deal with the modeling errors of this reduced model, the Approximation Error Model is used. The results show that excellent estimates can be obtained at feasible computational times.  相似文献   

11.
干熄锅炉内传热过程数学模型及其数值仿真   总被引:2,自引:1,他引:2  
在详细分析了干熄锅炉内传热过程的基础上,建立了干熄锅炉内传热过程数学模型。采用现场实测数据对所建立的数学模型进行了验证。在此基础上,仿真计算了典型工况下的理论产汽量,并分析了影响干熄锅炉产汽量的诸多因素。所做工作对干熄炉一锅炉系统的计算机优化控制具有重要的指导意义。  相似文献   

12.
结合脉动燃烧器高温燃烧室和尾管部分需要风冷的实际情况,采用数值模拟方法针对几种典型翅片的传热与流动特性进行了数值计算,比较分析了不同形式翅片的表面传热系数、№数和表面摩擦系数,最终为脉动燃烧器风冷翅片选择了较为合理的翅片形式。  相似文献   

13.
Inverse transient heat conduction problems of a multilayered functionally graded (FG) cylinder are presented. The approach is based on measurement of temperature on the outer surface of the cylinder to estimate the heat flux and convection heat transfer coefficient on its inner surface. The non-Fourier heat transfer equation is employed to accurately formulate the problem. The conjugate gradient method (CGM) is used for the optimization procedure and the incremental differential quadrature method (DQM) is applied to solve the direct, sensitivity, and adjoint problems. The accuracy of the presented approach is examined by simulating the exact and noisy data through different examples. Good accuracy of the obtained results validates the presented approach.  相似文献   

14.
热渗耦合的地下水源热泵抽灌井传热数值模拟   总被引:1,自引:0,他引:1  
基于达西定律,分析了饱和区土壤中地下水源热泵抽灌井传热机制,构建了热渗耦合共同作用下的数学模型,研究了有无地下水渗流及渗流速度对抽灌井周围温度场变化的影响,使用COMSOL Multiphysics软件对建立的模型进行了分析模拟.实例结果表明,该模型具有较好的适用性,为系统的优化设计与参数合理匹配提供了理论支持.  相似文献   

15.
In this paper an analysis of laminar heat transfer and fluid flow in a wavy fin-and-tube heat exchanger has been carried out. Three-dimensional (3D) numerical simulation results of a circular tube heat exchanger were compared with published numerical and experimental results. The computational fluid dynamics (CFD) procedure was validated by comparing average Nusselt numbers, and good agreement between published and calculated results has been accomplished. The influence of inlet air velocity, varying from 0.5 to 5 m s?1, as well as fin pitch, varying from 0.4 to 4 mm, on heat transfer and pressure drop conditions has been studied. The results have shown that there is an optimal fin pitch for each air velocity, which gives the best heat exchanger performance from the heat transfer point of view.  相似文献   

16.
为了增加同心套管式相变蓄热器的蓄能效果,采用环形肋片强化相变储能设备的传热,利用Fluent软件模拟了这种结构中石蜡相变的融化过程,得到了石蜡熔化过程温度场分布及熔化时间的规律,根据这些规律分析了肋片间距及厚度等参数对贮热管放热效果的影响。分析结果表明:石蜡的总融化时间随肋片间距增加而延长即传热效果变差,但是随着肋片厚度的增加而缩短,即传热效果变优,但是当或肋间距超过40mm和厚度超过2mm后,进一步增加肋片间距或者厚度对传热效果的影响变得不明显。  相似文献   

17.
余热锅炉的动态数学模型及数字仿真   总被引:16,自引:1,他引:16  
裘浔隽  杨瑜文  林中达 《动力工程》2002,22(6):2078-2083,2033
余热锅炉动态数学模型是分析联合循环系统动态特性的必要环节。作者着重对联合循环中的余热锅炉的各部件进行了理论建模和模型简化,对燃气轮机出口烟气温度变化和汽机调节汽阀开度变化时余热锅炉的动态特性进行数字仿真,并对仿真结果进行了分析。  相似文献   

18.
Functionally graded materials (FGMs) are used in many applications that presumably produce the wave nature of thermal energy transport. This study investigates the hyperbolic and parabolic heat conduction problem for a solid slab made of FGM numerically. A constant heat flux is considered at both sides of the slab, and boundaries dissipate heat by radiation into an ambient. An exponential space-dependent function of volume fraction is considered. MacCormack's explicit predictor-corrector scheme is used to solve the nonlinear equation in order to handle discontinuities at the wave front quite satisfactorily with small oscillations. Results are compared to the results obtained with the assumption of constant and linear spatial variation of volume fraction function. Further effects of different nondimensional numbers on the temperature distribution is sought. Numerical results are validated by the analytical solution of a special case that shows excellent agreement.  相似文献   

19.
Ertan Buyruk 《传热工程》2018,39(15):1392-1404
In the present study, the potential of rectangular fins with different fin types of inner zigzag-flat-outer zigzag (B-type) and outer zigzag-flat-outer zigzag (C-type) and with different fin angles of 30° and 90° for 2 mm fin height and 10 mm offset from the horizontal direction for heat transfer enhancement with the use of a conjugated heat transfer approach and for pressure drop in a plate fin heat exchanger is numerically evaluated. The rectangular fins are located on a flat plate channel (A-type). The numerical computations are performed by solving a steady, three-dimensional Navier–Stokes equation and an energy equation by using FLUENT software program. Air is taken as working fluid. The study is carried out at Reynolds number of 400 and inlet temperatures, velocities of cold and hot air are fixed as 300 K, 600 K and 1.338 m.s?1, 0.69 m.s?1, respectively. This study presents new fin geometries which have not been researched in the literature for plate fin heat exchangers. The results show that while the heat transfer is increased by about 10% at the exit of a channel with the fin type of C, it is increased up to 8% for the fin angle of 90° when compared to a channel with A-type under the counter flow. The heat transfer enhancements for different values of Reynolds number and for varying fin heights, fin intervals and also temperature distributions of fluids are investigated for parallel and counter flow.  相似文献   

20.
针对外壁受热的增压锅炉锅筒,提出了求解其截面瞬态温度场的导热正反问题耦合解法.根据锅筒外壁是否受热,将其外壁划分为受热和不受热2个区域.对于不受热区域,沿外壁周向布置热电偶,根据实际测量所得温度,利用导热反问题解法求解该区域的温度场;对于受热区域,利用导热正问题解法求解其温度场;对于耦合边界区域,将不受热区域反问题解法得到的交接边界处温度赋值给受热区域正问题解法作为已知边界条件,从而实现正反问题耦合,得到整个锅筒截面的瞬态温度场.利用Ansys软件对锅炉冷态启动过程中锅筒的温度场进行了计算,并与正反问题耦合解法的计算结果进行了对比.结果表明:正反问题耦合解法具有较高的精度,在复杂边界条件下具有很好的适应性,能够满足工程应用的需要.  相似文献   

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