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In selective laser melting, there are two different laser scan pattern including point exposure scan and continuous exposure scan. Different laser scan pattern has a significant effect on the thermal behavior and fluid flow of molten pool. In this paper, under the same energy input, the effects of laser scan pattern on the temperature evolution behavior, molten pool dimensions, fluid flow and cooling rate are thorough studied by method of numerical simulation. Experiments for point exposure are carried out which are in a good agreement with the numerical results. [ABSTRACT FROM AUTHOR]

Simulation capacity is essential to the engineering design of industrial products with complex functions. This paper discusses a numerical algorithm to simulate the multiscale heat and moisture transfer in the thermal smart clothing system. A group of multiscale nonlinear models are proposed to describe the mix-type coupled heat and moisture transfer in the human body, fabrics, fiber material, and phase change material (PCM) particles. The dynamic thermal boundary conditions among individuals are considered and described to integrate the multiscale models. The coupled partial differential equations of the models are discretized by the finite volume method, and the numerical scheme for the thermal smart clothing simulation are developed considering the specification of wearing scenarios. To validate the models and simulation scheme, the simulation results and experimental results with the same clothing and wearing conditions are compared and discussed. Furthermore, a series of simulation cases are made to present the application of this numerical algorithm in practical design by expressing a sequence of design issues through the simulation results for the designers. This simulation scheme is helpful in the engineering design process of thermal smart clothing to identify the thermal quality of the clothing in advance and thus reduce the design cost. [ABSTRACT FROM AUTHOR]

Energy conversion devices undergo thermal loading during their operation as a result of inefficiencies in the energy conversion process. This will eventually lead to degradation and possible failure of the device if the heat generated is not properly managed. The ability to accurately predict the thermal behavior of such a device during the initial developmental stage is an important requirement. However, accurate predictions of critical temperature is challenging due to the variation of heat transfer parameters from one device to another. The ability to determine the model parameters is key to accurately representing the heat transfer in such a device. This paper presents the use of an inverse identification technique to estimate the model parameters of an energy conversion device designed for vehicular applications. To simulate the imperfect contact and the presence of insulating materials in the permanent magnet electric machine, thin material are introduced at the component interface of the numerical model. The proposed inverse identification method is used to estimate the equivalent thermal conductance of the thin material. In addition, the electromagnetic losses generated in the permanent magnet is also derived indirectly from the temperature measurement using the same method. With the thermal properties and input parameters of the numerical model obtained from the inverse identification method, the critical temperature of the device can be predicted more accurately. The deviation between the maximum measured and predicted winding temperature is less than 2.4%. [ABSTRACT FROM AUTHOR]

The arc welding process involves thermal cycles that cause the appearance of undesirable residual stresses. The determination of this thermal cycle is the first step to a thermomechanical analysis that allows the numerical calculation of residual stresses. This study describes the formulation of a 2D finite element with through the thickness parabolic temperature distribution, including an element estabilization procedure. The 2D element described in this paper can be used to perform thermal analysis more economically than 3D elements, especially in plates, because the number of degrees of freedom through the thickness will always be three. A numerical model of a tungsten arc welding (GTAW) setup was made based on published experimental results. Size and distribution of the heat source input, thermal properties dependent on temperature, surface heat losses by convection and latent heat during phase change were considered. In parallel the same setup was modeled using ANSYS software with 3D elements (SOLID70) to compare against 2D numerical results. The results obtained by 2D model, 3D model and experimental data showed good agreement. [ABSTRACT FROM AUTHOR]

Light pipes transmit daylight into building interiors. Their installation into thermally insulated roofs of low energy buildings can be a problem because of thermal bridges and condensation problems. This article is focused on a CFD simulation thermal analysis that includes four variations of light pipes with a segment of a flat roof. Common light pipes with a hollow light guiding tube were compared to special light pipes containing an additional glass unit located inside the tube. The additional glass units increase thermal resistance and reduce condensation risks of the light guiding systems. The light pipes were compared in two different simulation models run in ANSYS Fluent software and the CalA program. Temperature profiles and air flow patterns of the cross sectional profiles of the light pipes served to determine the total heat transmittance and heat losses of the studied light pipes installed in a segment of a thermally insulated flat roof. The paper compares simplified 2D rotational–symmetrical numerical model based on the thermal diffusion equation with the complex 3D CFD numerical simulation. The results confirm that the simplified 2D numerical model is suitable for the thermal evaluation of the light pipes containing an additional glass unit, too. The additional glass unit with the triple glass improves thermal resistance up to 88% in case of light pipe with diameter 600 mm and reduces optical transmittance to 28%. [ABSTRACT FROM AUTHOR]

Abstract: In this paper we document the relationship between complex flow architecture and global performance for assemblies of heat pumps coupled thermally with the ground through a single U-shaped loop with circulating fluid. The assemblies vary according to heat pump numbers, sizes and locations along the loop. They are classified in a systematic way, and their performance is documented in three classes of designs: assemblies of heat pumps of the same size, heat pumps distributed equidistantly, and large numbers of heat pumps distributed almost continuously on a long loop. The work is based on numerical simulations, and on an analysis that holds in the limit of heat pumps distributed continuously. The relationship between flow architecture and global performance (heat transfer density) serves as guide for the energy design of high-density urban settlements in the future. [Copyright &y& Elsevier]

• Open-source system for integrated simulation of structures in fire. • Coupled CFD analysis with FEM analysis with an automatic HT component. • Allowance for model building in CAD/BIM and transfer into an OpenSees using a GUI. • The HT analysis was validated against recent experimental data and EC predictions. • The Cardington large compartment test used as a demonstration for the integrated system. The collapse of several tall composite buildings over the last two decades has shown that the performance of tall, composite and complex buildings in fire is a necessary design consideration that ought to go beyond simple code compliance. To this end, several advancements in the field of numerical simulation of both the fire and the thermomechanical response of structures have been made. In isolation, the practical benefit of these advancements is limited, and their true potential is only unlocked when the results of those numerical simulations are integrated. This paper starts by showcasing recent developments in the thermal and thermomechanical analysis of structures using OpenSees. Integration of these developments into a unified simulation environment combining fire simulation, heat transfer, and mechanical analysis is then introduced. Finally, a demonstration example based on the large compartment Cardington test is used to showcase the necessity and efficiency of the developed simulation environment for thermomechanical simulation of composite structures in fire. [ABSTRACT FROM AUTHOR]