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The present paper describes the applicability of hybrid transfinite element modelling/analysis formulations for non‐linear heat conduction problems involving phase change. The methodology is based on application of transform approaches and classical Galerkin schemes with finite element formulations to maintain the modelling versatility and numerical features for computational analysis. In addition, in conjunction with the above, the effects due to latent heat are modelled using enthalpy formulations to enable a physically realistic approximation to be effectively dealt computationally for materials exhibiting phase change within a narrow band of temperatures. Pertinent details of the approach and computational scheme adapted are described in technical detail. Numerical test cases of comparative nature are presented to demonstrate the applicability of the proposed formulations for numerical modelling/analysis of non‐linear heat conduction problems involving phase change.

This paper describes one of the new package cooling technology concepts using low melting point alloys in order to perform high density packaging. Two kinds of cooling alloy materials, Bi/Sn/In and Bi/Pb/Sn/ln, whose melting points were less than 80°C and whose costs were low, were selected. The experimental substrate sample was fabricated by greensheet technology on which a tungsten metallised resistor heater was formed. Two kovar weld rings were brazed together to the top side and back side surfaces of the substrate individually. One kovar metal shell was laser welded to the top side weld ring in order to protect many devices. Another kovar metal shell, with a hole in the centre, was laser welded to the back side weld ring. The low melting point alloy was melted and poured into the back side kovar shell through the hole in a liquid state. After it was cooled and changed into a solid state, the hole was sealed hermetically with a small kovar metal cap by a laser beam. The authors performed a thermal experiment and confirmed that the substrate back surface temperature was fixed at the cooling alloy material's melting point for several minutes by thermal absorption while the low melting point alloy phase changed from its original solid state into a liquid state. This new package cooling technology is extremely useful for a high power motor drive circuit package which consists of many high power transistor chips and other analogue IC chips, and whose motor drive operation is performed intermittently for several minutes with some interval times.

The purpose of this paper is to analyze the performance of a data center and thermal management by using phase change material (PCM). Numerical studies were conducted for two dimensional model of data center and installation of PCM at different locations.

Finite volume method was used for the unsteady problem, while impacts of air velocity and PCM location on the flow field, thermal pattern variations and phase change dynamics were evaluated. Three different locations of the PCM were considered while air velocity was also varied during the simulation. Thermal field variations and cooling performance of the system for different PCM location scenarios were compared.

It was observed that the installation of the PCM has significant impacts on the vortex formation, thermal field variation within the system and its performance. The left, right and top wall installation of the PCM changed the thermal patterns near the heat cell of the data centre. The phase change process is fast for the upper wall installation of the PCM, while the discrepancy of the melt fraction dynamics between different air flow at this position is minimum. The case where PCM placed in the upper wall at the highest air velocity is the best configuration in terms of heat storage. The utilization of PCM and changing its locations provide an excellent tool for thermal management and cooling performance of data centre.

Results of this study can be used for initial design and optimization of cooling systems for thermal management of data centers while the importance of the high-performance computing becomes very crucial for the advanced simulations in different technological applications.

A method has been developed for conjugate heat transfer analysis of fluid flow inside parallel channels formed by a phase change material (PCM) separated from the fluid by a wall. The phase change in the PCM is two dimensional and a hybrid analysis consisting of an analytical solution in one direction and a finite‐difference method in another direction is used to solve for the temperature in the PCM. The heat transfer fluid (HTF) inlet temperature is given and the heat transfer between the HTF and the PCM is treated as a conjugate problem that requires no iterations to obtain a solution. The numerical results are found to be stable, convergent, and accurate. Application of the method to the solution of heat extraction from a phase‐change energy storage unit is given in detail and the numerical results are shown to be accurate, based on an energy conservation analysis, to within 3%.

The axisymmetric steady‐state convective‐diffusive thermal field problem associated with direct‐chill, semi‐continuously cast billets has been solved using the dual reciprocity boundary element method. The solution is based on a formulation which incorporates the one‐phase physical model, Laplace equation fundamental solution weighting, and scaled augmented thin plate splines for transforming the domain integrals into a finite series of boundary integrals. Realistic non‐linear boundary conditions and temperature variation of all material properties are included. The solution is verified by comparison with the results of the classical finite volume method. Results for a 0.500[m] diameter Al 4.5 per cent Cu alloy billet at typical casting conditions are given.

The purpose of this paper is to present a 2D numerical simulation of natural convection and phase‐change of succinonitrile in a horizontal Bridgman apparatus. Three different heat transfer mechanisms are specifically studied: no growth, solidification and melting.

The analysis is carried out with a preexisting thermally coupled fixed‐mesh finite element formulation for generalized phase‐change problems.

In the three cases analyzed, the predicted steady‐state liquid‐solid interfaces are found to be highly curved due to the development of a primary shallow cell driven by the imposed furnace temperature gradient. In the no growth case, the heating and cooling jackets remain fixed and, therefore, a stagnant liquid‐solid interface is obtained. On the other hand, the phase transformation in the solidification and melting cases is, respectively, controlled by the forward and backward movement of the jackets. In these last two growth conditions, the permanent regime is characterized by a moving liquid‐solid interface that continuously shifts with the same velocity of the jackets. The numerical results satisfactorily approach the experimental measurements available in the literature.

The numerical simulation of the no growth, solidification and melting cases in a horizontal Bridgman apparatus using a finite element based formulation is the main contribution of this work. This investigation does not only provide consistent results with those previously computed via different numerical techniques for the no growth and solidification conditions but also reports on original numerical predictions for the melting problem. Moreover, all the obtained solid‐liquid interfaces are validated with experimental measurements existing in the literature.

The study of pressure‐volume‐temperature (PVT) process is necessary to understand the physical behaviour of materials. This paper seeks to develop a simulation procedure to predict phase behaviour.

The procedure consisted of the application of a thermo‐mechanical nonlinear model that simulated the behavior of the test sample in the PVT apparatus. Software Ansys was used for modeling this case, making a subroutine in APDL language. The real time data of the experimental procedure in PVT apparatus were applied in the computer simulation, that is the real time of application of pressure and heating scaling of the sample were taken into account. A specific case was simulated and its results compared with those obtained from the real experimental test. In order to evaluate phase changes, enthalpy was considered using an approximated expression described in the paper.

Results obtained from the simulation were compared with the resulting isobaric graphics of the experimental test. Results show a good correlation, obtaining in addition stress‐strain behavior of the sample. This simulation procedure allows one in a simple way to vary the properties and characteristics of the sample. This makes the computer simulation a useful tool together with the experimental test, in the development of novel materials.

Results of the numerical simulation are based on the properties and characteristics of the sample. In this study, real data of the material were used; however, some others had to be assumed based on references on this topic.

The coupled field analysis and the subroutine built in an Ansys environment are of a general purpose applicable to many kinds of material without practical limitations but getting a priori the required data and properties needed for running the simulation test.

Computer simulation of PVT process is not a common procedure – the experimental study of the material is mainly the procedure used to define the stated equations of a material and for knowing their phase changes. Computer simulation is a procedure that provides other important features of the material that the experimental study cannot produce simultaneously.

The purpose of this paper is to develop a new local radial basis function collocation method (LRBFCM) for one‐domain solving of the non‐linear convection‐diffusion equation, as it appears in mixture continuum formulation of the energy transport in solid‐liquid phase change systems.

The method is structured on multiquadrics radial basis functions. The collocation is made locally over a set of overlapping domains of influence and the time stepping is performed in an explicit way. Only small systems of linear equations with the dimension of the number of nodes in the domain of influence have to be solved for each node. The method does not require polygonisation (meshing). The solution is found only on a set of nodes.

The computational effort grows roughly linearly with the number of the nodes. Results are compared with the existing steady analytical solutions for one‐dimensional convective‐diffusive problem with and without phase change. Regular and randomly displaced node arrangements have been employed. The solution is compared with the results of the classical finite volume method. Excellent agreement with analytical solution and reference numerical method has been found.

A realistic two‐dimensional non‐linear industrial test associated with direct‐chill, continuously cast aluminium alloy slab is presented.

A new meshless method is presented which is simple, efficient, accurate, and applicable in industrial convective‐diffusive solid‐liquid phase‐change problems with non‐linear material properties.

Phase change materials have been a main topic in research for the last 20 years. They have also been used in many engineering applications, especially in the fields of thermal storage and insulation. They are used for ice storage, building applications, in the field of solar energy storage, heat pumps, heat distribution systems, air conditioning, green houses, solar collectors and cookers, for improving thermal comfort in vehicles, and for the conservation and transport of temperature-sensitive materials such as electronic materials, food, the transport of medical tissue, and engines or hydraulic machines. Recently, PCMs (Phase Change Materials) have entered the textile market for use in increasing the thermal comfort of garments. In such extreme applications of textiles as diving suits, ski wear, and underwear, PCMs can impart outstanding properties to garments. Their insulating properties may prevent the wearer from fatal consequences. In this paper, the use of PCMs, methods of evaluation, and methods and areas of application in textiles are discussed.

Heat capacity enhancement is important for variety of applications, including microchannel cooling and solar thermal energy conversion. A promising method to enhance heat capacity of a fluid is by introducing phase change particles in a flow system. The purpose of this paper is to investigate heat capacity enhancement in a microchannel flow with the presence of phase change material (PCM) particles.

Discrete phase model (DPM) and homogeneous model have been compared in this study. Water is used as the carrier fluid and lauric acid as the PCM particles with different volume concentrations, ranging from 0 to 10%. Both the models neglect the particle‐particle interaction effects of PCM particles.

The DPM indicates that presence of 10% volume concentration of PCM particles does not cause an increase in the pressure drop along the channel length. However, prediction from the homogeneous model shows an increase in the pressure drop due to the addition of nanoparticles in such a way that 10% volume concentration of particles causes 34.4% increase in pressure drop.

The study covers only 10% volume concentration of PCM particles; however, the model may be modified to include higher volume concentrations. The laminar flow is considered; it may be extended to study the turbulence effects.

This work provides a starting framework for the practical use of different PCM particles, carrier fluid properties, and different particle volume concentrations in electronic cooling applications.

The work presented is original and the findings will be very useful for researchers and engineers working in microchannel flow in cooling and thermal storage applications.