G5
Process Simulation 1

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08:35
conference time (CEST, Berlin)
Adaption of the Aluminium Electrolysis to Volatile Power Supply: Development of a Predictive Model to Investigate the Thermal Behavior of a Cell
26/10/2021 08:35 conference time (CEST, Berlin)
Room: G
N. Janssen, H. Gesell, R. Gutt, U. Janoske (Bergische Universität Wuppertal, DEU)
N. Janssen, H. Gesell, R. Gutt, U. Janoske (Bergische Universität Wuppertal, DEU)
A result of the energy transition in Germany, widely known as ’Energiewende’, is a volatile supply of energy available to consumers. These fluctuations can be compensated by synchronizing industrial processes, named ’Demand Side Management’. Aluminium production plays a key role, here. On the one hand, the energy consumption is significant (more than 1 % of German electricity consumption), on the other hand, the process itself offers a great potential for flexibility. Generally, electrolysis cells are operated with a constant current. An adaptation of the process control to fluctuating input power is required. The three submissions named ’Modeling of aluminium electrolysis process: part I-III’ each show approaches to solving individual challenges that arise as a direct result of this. This work deals with the prediction of the bath temperature depending on future current modulations. The temperature is a key parameter for a stable operation of the cell. The realization of the future prediction model is implemented in Matlab®/Simulink®. The model represents all relevant physical and chemical phenomena involved in aluminium production. Furthermore, interventions in the process, such as the changing of anodes, the removal of aluminium or the feeding with aluminium oxide can be simulated. In order to generate precise predictions, the model is adapted to the specific temporary properties of the investigated cell. This is done using an optimization algorithm that mainly takes thermal properties into account. It is shown that a prediction of the temperature in the cell is possible with a deviation of less than 3° C for a current modulation of up to 10 kA after 24 hours. By means of this model, a statement about the process stability in the case of possible future current modulations can be achieved. By simulating different operating modes at high current modulation, the maximum possible current modulation can be determined.
Aluminium electrolysis; Hall-Héroult process; Temperature prediction, Digital Twin, Matlab®/Simulink®
08:55
conference time (CEST, Berlin)
Impinging Jet Flow and Heat Transfer for Industrial Drying Applications
26/10/2021 08:55 conference time (CEST, Berlin)
Room: G
G. Klepp, G. Langer, Ali Chitsazan (OWL University of Applied Sciences and Arts, DEU)
G. Klepp, G. Langer, Ali Chitsazan (OWL University of Applied Sciences and Arts, DEU)
Multiple impinging jets are used in many industrial applications for cooling, heating or drying. For the single impinging jet a variety of experimental data and numerical results are available in the literature. In industrial applications a variety of geometric arrangements (nozzle shapes and arrangements) as well as operating conditions (e.g. moving surfaces) are used and the data available therefor is much scarcer and often empirical. The flow and heat transfer for multiple jets impinging on moving sheets, as used in paper drying, is analysed in order to optimize the performance of the jets. Numerical analysis is performed to investigate the relevant flow features and assess the influence of the main parameters and optimize the design. For simple repetitive geometries (e.g. round or planar nozzle) LES is a feasible approach. For arrays of multiple different jets this is still too expensive and a RANS approach is used. The simulations are performed with the k-omega SST model and validated with respect to experimental data and LES simulations. The local heat transfer is influenced by the turbulence in the adjacent bulk flow. Thus the results are influenced by the quality of the turbulence modeling, i.e. the turbulence model used and its implementation. This is shown for the secondary peak in the Nusseltnumber distribution for the impinging round jet. The flow for slot jets at moderate Reynoldsnumbers is analysed with LES. For higher Reynoldsnumbers and for arrays of round jets the k-omega SST model is used. The numerical results are used to gain some insight into the flow phenomena influencing the heat transfer. The heat transfer for particular designs can be predicted. Using numerical results correlation equation of dimensionless numbers are derived. The numerical model can also be used as an input into an optimization algorithm for the design of a nozzle field. Thus a good solution with regard to minimum energy requirement for the drying process and minimum strain for the sheets can be found. In a first step it is possible to improve the operating conditions, flow rate, air temperature, sheet velocity. In a second step the arrangement of the nozzles, i.e. spacing and distance to surface can be optimized. Finally using this numerical approach also the nozzle orifices can be designed accordingly.
jet flow, heat transfer, drying of sheets, RANS, LES
09:15
conference time (CEST, Berlin)
Numerical and Experimental Study of Dual Scale Flow in RTM with Anisotropic Tow Saturation
26/10/2021 09:15 conference time (CEST, Berlin)
Room: G
S. Facciotto, A. Pickett, P. Middendorf (Universität Stuttgart, DEU); P. Simacek, S.G. Advani (University of Delaware, USA)
S. Facciotto, A. Pickett, P. Middendorf (Universität Stuttgart, DEU); P. Simacek, S.G. Advani (University of Delaware, USA)
In the modern industry Resin Transfer Molding (RTM) is a well-known low cost technique to produce high quality composite materials parts in a relatively short time. The process injects a pressurized resin in a closed mold containing a fiber preform to fill all the empty spaces between fibers and inside fiber tows. Often modeling of infiltration processes is performed treating the material as a homogeneous porous medium. However, engineering reinforcements used in the industry are often dual scale presenting different filling rate for the pores inside the fiber tows and for the regions between the fiber tows. One of the main issues related with the RTM process are flow induced defects and the presence of dual scale flow could potentially lead to meso and microvoid generation and entrapment. Once a part is cured, such voids influence negatively its performance, reducing mechanical properties and, in some cases, representing localized spots for crack initiation and future failure. In this work, the dual scale nature of the process is modeled using Liquid Injection Molding Simulation (LIMS) software. The saturation of the tows is analyzed using a network of one-dimensional elements, which are attached to the mesh that represents the bulk preform. This network is modified to take into account the anisotropic permeability of the fiber tows and the architecture of the reinforcement. Capillary effects deriving from the compacted tows are also included. The model is validated with experiments, in which flow front position and dual scale filled regions are measured optically. Two geometries are investigated, first a flat plate geometry, and second a C-shaped spar. Role of various processing conditions is also included in this study; such as the effect of vacuum conditions on bulk and tow filling during the impregnation of the reinforcement, and on the final quality of the part in terms of void content.
RTM, Dual Scale Flow Modeling, Tow Saturation
09:35
conference time (CEST, Berlin)
Effect of Process Parameters on the Temperature Field During Electrofusion Welding of Glass/PE Thermoplastic Composite Pipes
26/10/2021 09:35 conference time (CEST, Berlin)
Room: G
A. Al Obedan, R. Tomlinson (University of Sheffield GBR); A. Traidia (Saudi Aramco, SAU)
A. Al Obedan, R. Tomlinson (University of Sheffield GBR); A. Traidia (Saudi Aramco, SAU)
The replacement of metallic pipes used in the energy industry by corrosion-free, lighter and flexible, non-metallic pipes has increased dramatically over the past decades. Single layer thermoplastic pipes have been used extensively in low pressure water and gas applications whereas three-layer thermoplastic composite pipes (TCP) increasingly are being adopted in higher pressure applications, such as oil and gas flowlines and water injection lines. The majority of TCP are joined by metallic connectors, unlike single layer thermoplastic pipes which are usually joined by electrofusion welding. Extending the capability of electrofusion coupling to high pressure TCP offers the advantage of having a full non-metallic system (i.e., corrosion-free), improved sealing capacity and potentially a lower cost solution for some selected applications. However, joining TCP using electrofusion welding poses a number of challenges. Among the important considerations, special attention should be given to the behaviour of the reinforced composite laminate layer during the welding process, as excessive heat may disturb the material microstructure and hence the mechanical properties of the pipe. Finite element modelling is required to understand the effect of welding parameters on the thermal response of TCP during electrofusion welding. In this study, a 2D multiscale model representing the pipe/fitting assembly is developed using COMSOL Multiphysics software. The purpose of this model is to simulate the transient heat transfer during electrofusion welding of Glass-PE TCP with the aim of optimizing the welding parameters and coupler design to achieve the required long-term joint performance. Temperature dependent material properties, thermal surface resistivity, material phase change and thermal expansion are accounted for in the model. A special attention is given to the heat source model in order to better simulate the heat input into the pipe material during the welding process. A sensitivity analysis is carried out to determine the influence of various parameters on the heat transfer including the power input, heating wire size and depth, contact between the fitting and the pipe, and thickness of the external pipe layer. An experimental validation is conducted with a real pipe/fitting, and the temperature profile is recorded during the entire welding cycle utilizing an infrared camera and pre-installed thermocouples at different depths and locations in the pipe/fitting assembly. The results of the experiment are used to calibrate the key model parameters at different welding times.
Electrofusion welding, Joining thermoplastics, Thermoplastic composite pipes, Multiscale modelling
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