Simulation

With the rapid development of the microelectromechanical systems (MEMS) field, the demand for small-scale metallic components has significantly increased. Among the manufacturing methods for micro metal structures, the LIGA (Lithographie, Galvanoformung, Abformung) process, utilizing electroforming, offers high dimensional accuracy and surface smoothness; however, it has limitations such as expensive equipment and a lack of design flexibility. The integration of additive manufacturing and electroforming processes alleviates the limitations of the LIGA process in producing micro and meso metal structures. Environmental parameters during the electroforming process have a considerable impact on surface morphology, the occurrence of voids, and dendritic growth of the final product. In this study, the effects of various environmental parameters, such as the anode-cathode distance, the acidic or non-acidic nature of the electrolyte, copper sulfate concentration, and the state of the stirring system (on or off), on the surface morphology of microstructures produced through the integration of additive manufacturing and electroforming of copper were investigated. Additionally, to save on costs and testing time, numerical simulation of the electroforming process was conducted using COMSOL software to predict the thickness profile of the deposited layer during the process. Experimental results indicate that the addition of 78 grams of sulfuric acid to the electrolyte results in a significant improvement in surface smoothness. Furthermore, at low concentrations of copper sulfate (approximately 80g/l), dendritic growth becomes predominant on the layer. Experimental and numerical investigations on the effect of anode-cathode distance revealed that this parameter has a minor impact on surface roughness and thickness of the deposited layer. The numerical results showed a maximum error of 7.5 percent compared to the experimental model.

The use of interfacial solar evaporation systems can be a suitable method to deal with the problem of fresh water shortage in the world. Interfacial solar evaporation systems can be widely used in the production of fresh water due to the use of solar energy as a without any costs energy and no environmental effects and also free from high pressure operations and no need for moving parts. But in order to use interfacial solar evaporation system for practical application, evaporation rate with high efficiency is required. In this research, the performance of a hollow cylindrical interfacial solar evaporation system with nature inspired water distribution to steam generation has been evaluated by numerical simulation. This system can absorb solar radiation more effectively. In this study, in order to accurately investigate the performance of the interfacial solar evaporation systems, steam generation and system efficiency were evaluated by changing environmental factors. Also, in order to investigate the performance of the interfacial solar evaporation systems under different angles of solar radiation in real world conditions, the rate of steam generation in two days of summer solstice and winter solstice in Tehran city has been evaluated. The results of this research show that the cylindrical interfacial solar evaporation system can have a steam generation rate of 3.09 kg/m2.h and 9.09 kg/m2.h in winter solstice and summer solstice respectively in Tehran city with wind flow

The current research has studied the effect of the input mass flow rate of paraffin fuel and dinitrogen oxide oxidizer, O/F ratio in the combustion chamber of a hybrid rocket on the quantities of chamber such as its pressure, thrust and specific impulse. The combustion chamber as well as a peripheral area are included in the calculation area. A two-dimensional steady-state simulation with a Reynolds-Averaged Navier–Stokes (RANS) approach using the standard κ-ε turbulence model together with the Eddy Dissipation Model (EDM) is used for the chemistry-turbulence interaction (TCI). Oxidizer and fuel enter the field in gas phase. The grids are structured. The simulation results are compared with the experimental data of the validation article and in the simulation, the highest average deviation value is 6.65%. By increasing the O/F ratio by 27.76% in the two-dimensional simulation, the average pressure of the combustion chamber has increased by 38.22%, the average thrust has increased by 52.29%, and the average specific impulse has increased by 18.28%. With the increase of O/F ratio by 38.43%, the average pressure of the combustion chamber has increased by 37.64%, the average thrust has increased by 53.31%, and the average specific impulse has increased by 19.28%.

In this research, the spring back phenomenon in the spacer part during the production process and after releasing the part from the forming force was simulated with the help of LS-Dyna software and the finite element method, and the results were verified by experimental testing. In this simulation, the software's Implicit solver was used to simulate the main part of the forming process and to simulate spring back. In the definition of the material model for simulation, its anisotropic behavior is ignored and the behavior of the material in the plastic region is described by Holman's power relation. In order to have more parameters for validating the simulation results, four different sheet forming modes were investigated in the experimental test and simulation, and in each of these modes, the speed parameter of the punch, the amount of friction between the tool and the sheet, and the thickness of the used sheet are different. By comparing the results of experimental testing and simulation, an error value of less than 10% has been observed in the calculation of the standard angle for spring back

Grain refinement through dynamic recrystallization is one way to improve the mechanical properties of high nitrogen austenitic stainless-steel ingots during hot rolling. In this paper, by using simulation based on the finite element method and experimental results, the effect of conventional rolling and gradient temperature rolling on the microstructural evolution of Nitronic 50 austenitic stainless-steel ingot during hot rolling is investigated. The results of simulations showed that strain in the center of the ingot be increased under a gradient temperature, while the maximum strain value in the conventional rolling is on the surface. The microstructural results obtained from optical microscopy for gradient temperature rolling showed strain value in the center is more than the surface. The temperature difference between the center and the surface leads to a significant reduction in the strength center of the ingot against the surface. The difference in average grain size of dynamic recrystallized for gradient temperature in the surface and center was less than 3μm. The existence of primary grains (68μm average grain size) and bulged grain boundaries in the center of ingot and refinement and small grains in the surface area (8.5μm) in conventional rolling (1000℃) showed that dynamic recrystallization, due to low effective strain and temperature, has not occurred in the center of the ingot. The almost uniform distribution of austenite grains in the direction of ingot thickness for gradient temperature rolling showed that this method is an appropriate method for hot rolling of austenitic steel ingots compared to conventional conditions.

The increasing population of the world, the change of style and the limited number of natural resources and energy all make freshwater industrial productions the main contenders for the cost-effective production of freshwater. In this research, the combination of combined cycle power plant (CCPP) using multiple effect distillation (MED) and reverse osmosis (RO) desiccation techniques is investigated through normal and advanced exergy, exergy-economic and exergy-environmental comprehensive analysis. First, CCPP thermodynamic modeling is done using mathematical programming method. Then, a mathematical model is presented to integrate the existing CCPP with MED and RO desalination plants. Finally, the aforementioned normal and advanced analyzes are performed to evaluate the main performance parameters of the integrated CCPP system and MED-RO desalination system, and to identify potential technical, economic, and environmental improvements. A case study is also presented about the Shahid Salimi Neka power plant located in the north of Iran along the Caspian Sea.The mathematical modeling method for this integrated system is solved in "MATLAB" program and its results are validated by "Thermoflex" software. The results show a 3.79% increase in fuel consumption after combining CCPP and water desalination facilities. The exergy efficiency of the advanced system is 42.7% and the highest combustion chamber exergy destruction cost is $1.09 per second. Economic and environmental analyzes of the integrated system also show that gas turbines have the highest investment cost ($0.047 per second). At the same time, the MED system has the highest environmental impact rate, i.e. 0.025 points per second.