scholarly journals Multi-objective Optimization to Increase Nusselt Number and Reduce Friction Coefficient of Water/Carbon Nanotubes via NSGA II using Response Surface Methodology

2020 ◽  
Vol 3 (1) ◽  
pp. 1-14
Author(s):  
Amin Moslemi Petrudi ◽  
Pourya Fathi ◽  
Masoud Rahmani
Keyword(s):  
Response Surface Methodology ◽  
Nusselt Number ◽  
Friction Coefficient ◽  
Response Surface ◽  
Pareto Front ◽  
Volume Fraction ◽  
Reynolds Numbers ◽  
Solid Particles ◽  
Nsga Ii ◽  
Engineering Sciences

Heat transfer science is one of the most important and most applied engineering sciences, with the importance of energy management and energy conservation being doubled. Because of their properties, nanofluids have been widely used in various industries, making them particularly important to study. In this paper, the Nusselt number and coefficient of friction with volume fraction ranging from 0 to 0.1 at approximately Reynolds numbers of 200 to 5000 are studied experimentally. Higher thermal conductivity, better stability, lower pressure drop was observed using nanoparticles of solid particles. NSGA II algorithm was used to maximize Nusselt number and minimum friction coefficient by changing temperature and volume fraction of nanoparticles. To obtain Nusselt number and friction coefficient based on the temperature and volume fraction of the nanoparticles, the experimental data response surface methodology was used and with increasing Reynolds number, the Nusselt number increased and the friction coefficient decreased. In order to evaluate the objective functions in the optimization, the response surface methodology is attached to the optimization algorithm. At the end, the Pareto Front and its corresponding optimal points are presented.

Application of Response Surface Methodology in the Optimization of Magneto-Hydrodynamic Flow Around and Through a Porous Circular Cylinder

2018 ◽  
Vol 34 (5) ◽  
pp. 695-710 ◽  
Author(s):  
S. M. Vahedi ◽  
A. Zare Ghadi ◽  
M. S. Valipour
Keyword(s):  
Response Surface Methodology ◽  
Nusselt Number ◽  
Drag Coefficient ◽  
Response Surface ◽  
Mhd Flow ◽  
Reynolds Numbers ◽  
Darcy Number ◽  
Optimization Process ◽  
Staggered Grid ◽  
Polar Coordinate

AbstractIn this study MHD flow around and through porous cylinder is numerically investigated. The governing equations are developed in polar coordinate arrangement in both porous and non-porous media on the basis of single-domain technique. The equations are solved numerically based on finite volume method over staggered grid structure. Nusselt number and drag coefficient are selected as two key parameters describing performance of this system. By applying response surface methodology the sensitivity of these parameters to main factors of the problem, including Stuart number, Darcy number and Reynolds number are quantified. RSM is also utilized to perform an optimization process to find the best condition in which the lowest drag force and highest heat transfer rate occur simultaneously. The CFD analysis is carried out for variant Reynolds numbers (10 ≤ Re ≤ 40), Darcy numbers (10-6 ≤ Da ≤ 10-2) and Stuart numbers (2 ≤ N ≤ 10). Streamlines and isotherms are presented to indicate the impacts of such parameters on heat and fluid flow. It can be seen that, Drag coefficient and Nusselt number increase by augmenting magnetic field strength. Beside, Darcy number and Reynolds numbers have a direct and inverse effect on Nuave and Cd, respectively. Results of optimization process show that Nuave and Cd are more sensitive to Reynolds and Stuart numbers, respectively, while they less sensitive to Darcy number. Moreover, it is revealed that the optimum condition occurs at Da = 10-2, Re = 38.1 and N = 4.49.

Optimization of phenolics and antioxidants extraction from Centaurium erythraea using response surface methodology

2021 ◽  
pp. 6455-6462
Author(s):  
Wissam Zam ◽  
Ali Ali ◽  
Dimah Saleem ◽  
Sahar Alali
Keyword(s):  
Antioxidant Activity ◽  
Response Surface Methodology ◽  
Response Surface ◽  
Volume Fraction ◽  
Quadratic Model ◽  
Natural Food ◽  
Solvent Ratio ◽  
Research Attention ◽  
Experimental Values ◽  
Centaurium Erythraea

In recent years, Centaurium erythraea extracts have attracted much research attention in the context of prevention or treatment of many diseases due to its bioactive compounds content and antioxidant activity. The antioxidants of C. erythraea are very effective as they possess excellent antioxidant activity. Thus, it can be used as a safe and natural food preservative. The aim of this study is to make extracts more effective by optimizing the extraction conditions of the phenolics and antioxidants from C. erythraea using response surface methodology (RSM) based on a central composite design (CCD). Two process variables (Methanol volume fraction and solid - solvent ratio) were evaluated at five levels (13 experimental designs). Multiple regression analyses were performed to obtain quadratic polynomial equations using RSM; each response was fitted by a quadratic model. The adequacy of the models was proven using the analysis of variance (ANOVA). The significant effects of the factors and their interactions on the extraction efficiency were investigated at 95% confidence interval. RSM indicated that the optimal extraction conditions were 71% methanol volume fraction and 2.2:10 solid:solvent ratio. Predicted values thus obtained were close to the experimental values indicating suitability of the model.

CFD Investigation of Al2O3 Nanoparticles Effect on Heat Transfer Enhancement of Newtonian and Non-Newtonian Fluids in a Helical Coil

2019 ◽  
Vol 14 (3) ◽  
Author(s):  
Javad Aminian Dehkordi ◽  
Arezou Jafari
Keyword(s):  
Heat Transfer ◽  
Aqueous Solution ◽  
Nusselt Number ◽  
Base Fluid ◽  
Volume Fraction ◽  
Reynolds Numbers ◽  
Helical Coil ◽  
Al2o3 Nanoparticles ◽  
Nanoparticles Volume Fraction ◽  
Computational Fluid Dynamics Cfd

Abstract The present study applied computational fluid dynamics (CFD) to investigate the heat transfer of Newtonian (water) and non-Newtonian (0.3 %wt. aqueous solution of carboxymethylcellulose (CMC)) fluids in the presence of Al2O3 nanoparticles. To analyze the heat transfer rate, investigations were performed in a vertical helical coil as essential heat transfer equipment, at different inlet Reynolds numbers. To verify the accuracy of the simulation model, experimental data reported in the literature were employed. Comparisons showed the validity of simulation results. From the results, compared to the aqueous solution of CMC, water had a higher Nusselt number. In addition, it was observed that adding nanoparticles to a base fluid presented different results in which water/Al2O3 nanofluid with nanoparticles’ volume fraction of 5 % was more effective than the same base fluid with a volume fraction of 10 %. In lower ranges of Reynolds number, adding nanoparticles was more effective. For CMC solution (10 %), increasing concentration of nanoparticles caused an increase in the apparent viscosity. Consequently, the Nusselt number was reduced. The findings reveal the important role of fluid type and nanoparticle concentration in the design and development of heat transfer equipment.

Predicting the Nusselt Number of Heterogeneous (Porous) Enclosures Using a Generic Form of the Berkovsky–Polevikov Correlations

2013 ◽  
Vol 135 (8) ◽  
Author(s):  
Hongtao Qiu ◽  
José L. Lage ◽  
Silvio L. M. Junqueira ◽  
Admilson T. Franco
Keyword(s):  
Nusselt Number ◽  
Natural Convection ◽  
Volume Fraction ◽  
Solid Particles ◽  
Scale Analysis ◽  
Interference Phenomenon ◽  
Vertical Boundary ◽  
Cold Walls ◽  
Fraction Porosity ◽  
Present Standard

A well-known set of Berkovsky–Polevikov (BP) correlations have been extremely useful in predicting the wall-averaged Nusselt number of “wide” enclosures heated from the side and filled with a fluid undergoing natural convection. A generic form of these correlations, dependent on only two coefficients, is now proposed for predicting the Nusselt number of a heterogeneous (fluid–solid), porous enclosure, i.e., an enclosure filled not only with a fluid but also with uniformly distributed, disconnected and conducting, homogeneous solid particles. The final correlations, and their overall accuracies, are determined by curve fitting the numerical simulation results of the natural convection process inside the heterogeneous enclosure. Results for several Ra and Pr, and for 1, 4, 9, 16, and 36 solid particles, with the fluid volume-fraction (porosity) maintained constant, indicate the accuracy of these correlations to be detrimentally affected by the interference phenomenon caused by the solid particles onto the vertical boundary layers that develop along the hot and cold walls of the enclosure; the resulting correlations, in this case, present standard deviation varying between 6.5% and 19.7%. An analytical tool is then developed for predicting the interference phenomenon, using geometric parameters and scale analysis results. When used to identify and isolate the interference phenomenon, this tool is shown to yield correlations with much improved accuracies between 2.8% and 9.2%.

scholarly journals Optimization of electro-Fenton oxidation of carbonated soft drink industry wastewater using response surface methodology

2020 ◽  
Vol 39 (2) ◽  
pp. 129
Author(s):  
Reza Davarnejad ◽  
Jamal Azizi ◽  
Amir Joodaki ◽  
Sepideh Mansoori
Keyword(s):  
Response Surface Methodology ◽  
Response Surface ◽  
Current Density ◽  
Volume Fraction ◽  
Soft Drink ◽  
Oxygen Demand ◽  
Volume Ratio ◽  
Organic Pollution ◽  
Molar Ratio ◽  
The Impact

The immense volume of highly polluted organic wastewater continuously generated in the beverage industry urges the design of new types of wastewater treatment plants. This study aimed to evaluate the applicability of the electro-Fenton (EF) technique to reduce organic pollution of real effluent from a carbonated soft drink factory. The impact of various process variables like pH, time, current density, H2O2/Fe2+ molar ratio, and the volume ratio of H2O2/soft drink wastewater (SDW) was analyzed using response surface methodology (RSM). The observed responses were in good agreement with predicted values obtained through optimization. The optimum conditions showed a chemical oxygen demand (COD) removal efficiency of 73.07 %, pH of 4.14, time of 41.55 min, current density of 46.12 mA/cm2, H2O2/Fe2+ molar ratio of 0.9802, and H2O2/SDW volume fraction of 2.74 ml/l. The EF process was able to effectively diminish the organic pollution, reduce the residence time and, therefore, the operating costs.

scholarly journals TỐI ƯU HÓA TIN CẬY VA ĐẬP CỦA ỐNG ĐA TẾ BÀO HÌNH VUÔNG CHỊU TẢI VA ĐẬP XIÊN

2021 ◽  
Vol 45 (03) ◽  
Author(s):  
TRẦN TRỌNG NHÂN
Keyword(s):  
Genetic Algorithm ◽  
Response Surface ◽  
Pareto Front ◽  
Nsga Ii ◽  
Knee Point

Tối ưu hóa tin cậy va đập của những ống hình vuông đa đa tế bào trong trường hợp va đập xiên được nghiên cứu trong bài báo này. Đối với các cấu trúc này, các chỉ số tin cậy va đập SEA và PCF được thu thập bằng cách sử dụng HYPERMESH / LS-DYNA. Pareto front thu được bẳng cách kết hợp response surface (RS) và Non-dominated Sorting Genetic Algorithm II (NSGA-II). Một “giải pháp tốt hơn” (hay còn gọi là knee point) được xác định từ Pareto front. Kết quả của nghiên cứu này là cơ sở tham khảo cho việc thiết kế các cấu trúc đa tế bào có khả năng tin cậy va đập tốt hơn.

scholarly journals Mathematical Modeling and Analysis of Tribological Properties of AA6063 Aluminum Alloy Reinforced with Fly Ash by Using Response Surface Methodology

Crystals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 403 ◽  
Author(s):  
Alaa Mohammed Razzaq ◽  
Dayang Laila Majid ◽  
Mohamad Ridzwan Ishak ◽  
Uday Muwafaq Basheer
Keyword(s):  
Response Surface Methodology ◽  
Fly Ash ◽  
Friction Coefficient ◽  
Wear Rate ◽  
Response Surface ◽  
Tribological Properties ◽  
Temperature Response ◽  
Wear Testing ◽  
Dry Sliding Wear ◽  
Testing Time

Lightweight, high-strength metal matrix composites have attracted considerable interest because of their attractive physical, mechanical and tribological properties. Moreover, they may offer distinct advantages due to good strength and wear resistance. In this research, AA6063 was reinforced with FA particles using compocasting methods. The effects of fly ash content, load, sliding speed and performance tribology of AA6063 –FA composite were evaluated. Dry sliding wear tests were carried out according to experimental design using the pin-on-disc method with three different loads (24.5, 49 and 73.5 N) and three speeds (150, 200 and 250 rpm) at room temperature. Response surface methodology (RSM) was used to analyze the influence of the process parameters on the tribological behavior of the composites. The surface plot showed that the wear rate increased with increasing load, time and sliding velocity. In contrast, the friction coefficient decreased with increasing these parameters. Optimal models for wear rate and friction coefficient showed appropriate results that can be estimated, hence reducing wear testing time and cost.

Process Parameters Optimization for Thin-walled Tube Push-bending Using Response Surface Methodology

2021 ◽  
Author(s):  
Wenlong Xie ◽  
Weihao Jiang ◽  
Yunfeng Wu ◽  
Hongwu Song ◽  
Siying Deng ◽  
...  
Keyword(s):  
Response Surface Methodology ◽  
Friction Coefficient ◽  
Response Surface ◽  
Process Parameters ◽  
Relative Length ◽  
Response Surfaces ◽  
Parameters Optimization ◽  
Process Window ◽  
Thin Walled Tube ◽  
Thin Walled

Abstract In this paper, the response surface methodology (RSM) and finite element (FE) simulation were applied to optimize the push-bending process parameters of the thin-walled tube with polyurethane mandrel. The objective of the present work is to predict the optimal set of process parameters including the relative length of the mandrel (L/D), the friction coefficient between die and tube (μ1), the friction coefficient between polyurethane and tube (μ2) and Poisson’s ratio of polyurethane (υ) to obtain qualified bent tubes. Three empirical models were developed to describe the relationship between process parameters and quality parameters of the bent tubes. In addition, the significant factors affecting the forming quality were analyzed using analysis of variance (ANOVA) of each model. Response surfaces were constructed to study the effect of each process parameter on the quality of the bent tubes. Finally, the process optimization window with the maximum thinning rate (ϑ) less than 20%, the maximum thickening rate (ψ) less than 17%, and the maximum cross-section ovality (ξ) less than 5% of the bent tube was established. Qualified bent tubes with diameter of 144 mm, wall thickness of 2 mm, and bending radius of 280 mm were formed experimentally by following the established process window.

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