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Abstract

Coal ash produced from thermal power plants as a substitute for conventional construction material has increased considerably in recent years. In the past, studies on partial replacement of soil were carried out with a single type of ash. Because of the insufficient evidence, limited research has been initiated on the productive usage of Fly and Bottom Ashes. This paper aims to study the properties of these materials and investigate their efficacy in road construction. Laboratory investigations were conducted to assess chemical and physical properties and mechanical performance to evaluate both ash types in pavement construction. The rutting factor is calculated for various combinations of coal ash materials with the addition of polypropylene fiber as a reinforcement in increments of 0.1% of its total weight with an aspect ratio of 200. The analytical tool ANSYS is used to validate the service life, vertical strain and quality of reinforced ash materials.
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Abstract

This article focuses on the finite element analysis (FEA) of the nonlinear behavior of a layered functionally graded material (FGM) plate as concerns displacement, stresses, critical buckling load and fundamental frequency. The material properties of each layer in an FGM plate are assessed according to a ceramic based simple power law distribution and the rules of mixture. The finite element model of a layered FGM plate is developed using ANSYS®15.0 software. The developed finite element model is used to study the static and dynamic responses of an FGM plate. In this paper, the effects of power law distribution, thickness ratio, aspect ratio and boundary conditions are investigated for central displacement, transverse shear stress, transverse normal stress, critical buckling load and fundamental frequency, and the obtained FEA results are in sound agreement with the literature test data results. Since the FGM is used in a high temperature environment, the FE analysis is performed for the FGM plate under a thermal field and then correlated. Finally, the FGM plate is analyzed under a thermomechanical load by using the current FE concept.
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Abstract

A rotor-stator spinning disk reactor for intensified biodiesel synthesis is described and numerically simulated in the present research. The reactor consists of two flat disks, located coaxially and parallel to each other with a gap ranging from 0.1 mm to 0.2 mm between the disks. The upper disk is located on a rotating shaft while the lower disk is stationary. The feed liquids, triglycerides (TG) and methanol are injected into the reactor from centres of rotating disk and stationary disk, respectively. Fluid hydrodynamics in the reactor for synthesis of biodiesel from TG and methanol in the presence of a sodium hydroxide catalyst are simulated, using convection-diffusion-reaction multicomponent transport model with the CFD software ANSYS©Fluent v. 13.0. Effect of operating conditions on TG conversion is particularly investigated. Simulation results indicate that there is occurrence of back flow close to the stator at the outlet zone. Small gap size and fast rotational speed generally help to intensify mixing among reagents, and consequently enhance TG conversion. However, increasing rotational speed of spinning disk leads to more backflow, which decreases TG conversion. Large flow rate of TG at inlet is not recommended as well because of the short mean residence time of reactants inside the reactor.
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Abstract

In this paper a two-disc spinning disc reactor for intensified biodiesel synthesis is described and numerically simulated. The reactor consists of two flat discs, located coaxially and parallel to each other with a gap of 0.2 mm between the discs. The upper disc is located on a rotating shaft while the lower disc is stationary. The feed liquids, triglycerides (TG) and methanol are introduced coaxially along the centre line of rotating disc and stationary disc. Fluid hydrodynamics in the reactor for synthesis of biodiesel from TG and methanol in the presence of a sodium hydroxide catalyst are simulated, using convection-diffusion-reaction species transport model by the CFD software ANSYS©Fluent v. 13.0. The effect of the upper disc’s spinning speed is evaluated. The results show that the rotational speed increase causes an increase of TG conversion despite the fact that the residence time decreases. Compared to data obtained from adequate experiments, the model shows a satisfactory agreement.
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Abstract

In recent time, as the Chinese consumption level increases, the consumption quantity of high-value fruits, vegetables and seafood products have been increasing year by year. As a consequence, the traffic volume of refrigerated products also increases yearly and the popularization degree of the cold-chain transportation enhances. A low-temperature environment should be guaranteed during transportation, thus there is about 40% of diesel oil should be consumed by the refrigerating system and the cold-chain transportation becomes very costly. This study aimed to explore methods that could reduce the cost of transport packages of refrigerated products. On the basis of the heat transfer theory and the fluid mechanics theory, the heat exchanging process of corrugated cases during the operation of refrigerating system was analyzed, the heat transfer process of corrugated cases and refrigerator van was theoretically analyzed and the heat balance equation of corrugated cases was constructed.
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Abstract

Gas emissions from underground sites to the atmosphere depend on many factors. Pressure drops are considered to be the most important. However, emissions can also be observed during the initial phase of the pressure rise, following a previous drop in pressure. On the other hand, gas emissions may not be detected when the pressure drops, especially when a previous pressure rise has taken place. The aim of the research was to determine the role of variations in baric tendency on airflow rate and its direction. To solve this problem a numerical model was built utilizing the Ansys Fluent software package. Subsequently, three scenarios of baric tendency variations were tested: a) rise – drop, b) drop – drop, c) drop – rise. The results showed inert behavior of gases. Under scenario (c), 1 hour after the change in tendency gases still were flowing out to the atmosphere. Considering scenario (a), it was proved that even during a pressure drop gas emissions do not take place, which can be crucial for further determination of the gas hazard at the surface or for assessment of the rate of gas emissions from a particular gas emitter. Scenario (b) merely gave an overview of the process and was mainly used for validation purposes. It gave a maximal CO2 concentration of 2.18%vol (comparable to measurements) and a CO2 mass flow rate 0.15kg/s. Taking into account greenhouse gas emissions this amounted to 514 kg CO2/h.
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Abstract

The presence of nanoparticles in heat exchangers ascertained increment in heat transfer. The present work focuses on heat transfer in a longitudinal finned tube heat exchanger. Experimentation is done on longitudinal finned tube heat exchanger with pure water as working fluid and the outcome is compared numerically using computational fluid dynamics (CFD) package based on finite volume method for different flow rates. Further 0.8% volume fraction of aluminum oxide (Al2O3) nanofluid is considered on shell side. The simulated nanofluid analysis has been carried out using single phase approach in CFD by updating the user-defined functions and expressions with thermophysical properties of the selected nanofluid. These results are thereafter compared against the results obtained for pure water as shell side fluid. Entropy generated due to heat transfer and fluid flow is calculated for the nanofluid. Analysis of entropy generation is carried out using the Taguchi technique. Analysis of variance (ANOVA) results show that the inlet temperature on shell side has more pronounced effect on entropy generation.
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