Applied Engineering Letters

133-147

Authors: P. Taheri, M. J. Taheri

This paper aims to provide a comprehensive feasibility study for the installation of a 100 MW wind power plant using the INVELOX system in Manjil, Gilan, in Northern Iran. In the first part of the paper, we provide a review of the status of wind energy installation in Iran. We then review the mathematical equations involved in wind power calculations. Afterwards, with the environmental data gathered from the corresponding authorities and open‐access sources, we analyzed the INVELOX system with its benefits and drawbacks. Then, based on the derived mathematical formulations, and using simulation software packages, the average wind power density is calculated, and the turbine system is designed accordingly. Finally, the economic profitability of this project was examined using a mathematical economic analysis and the COMFAR software package. In addition to the detailed feasibility study of this specific project, this article aims to provide a comprehensive literature review of the INVELOX system.

157-165

Authors: W. Sriboon, P. P. Pansila, S. Khunthong, S. Sukprasong

Lighting systems are used in all building types and consume large amounts of energy as well as adding to carbon dioxide (CO2) emissions. The aim of this research was to analyze energy consumption in the lighting systems of a new building. This study conducted a preliminary energy consumption audit of the Faculty of Science on the Kasetsart University Sriracha Campus, Thailand. The actual energy consumption in the study period and the specific energy index (specific energy consumption) were assessed. The results showed that the total electric power of all bulbs in the building was 72.13 kW and about 74 % were 20 W lamps. Annual energy consumption and carbon dioxide emissions were 157,753.73 kWh and 89,477.92 kg carbon dioxide for 9 hours use. The total energy consumption accounted for 1.64 % and 4.37 % based on 9 and 24 hours operation, respectively. The specific energy index was higher than the average for this university. Therefore, the energy consumption data obtained are very important in developing energy‐saving measures.

175-183

Authors: Ş. Danişman, E. Ersoy, C. Doğan

Titanium alloys are widely used in the aerospace industry due to their good mechanical properties. Especially Ti6Al4V alloy is preferred in machine parts that require specific strength in aerospace. However, the tribological properties of the Ti6Al4V alloy are poor and need improvement. It is possible to increase the life of Ti6Al4V alloys and improve their surface properties with various heat treatment and surface coating techniques. For this purpose, in this study, plasma nitriding heat treatment was first applied to the samples prepared from Ti6Al4V alloy. Then, TiN coating was carried out by the magnetron sputtering method. Surface roughness and surface hardness were measured before and after coating. Wear tests were performed with dry friction and room temperature conditions on Ti6Al4V alloys using the sliding velocity and normal load as variable parameters. The wear track widths, the weight loss of the samples, and the abrasive disc were measured. The steady‐state sliding regime average friction coefficients were determined from the recorded friction forces depending on the sliding distance. Normal load ‐ wear track widths, normal load ‐ friction coefficient graphics were created. Load wear track width plots showed that the wear track widths on the TiN coated and uncoated samples increased with the load. The fact that the track width values of the uncoated samples with the same load and velocity values were higher than the TiN‐coated samples showed that the TiN‐coated samples had higher wear resistance. In addition, it was observed that the friction coefficient values in the uncoated samples under constant sliding speed were relatively higher than the TiN‐ coated samples.

89-98

Authors: G. Kostadinov, P. Danailov, R. Dimitrova, M. Kandeva, T. Penyashki, V. Kamburov, A. Nikolov, B. Elenov

This paper examines the topography and roughness of coatings of hard alloyed materials deposited by electrospark deposition (ESD) on titanium and nickel alloys with different initial roughness. The influence of the electrode materials and the energy parameters of the ESD process on the roughness parameters Ra, Rt, Rq, Rz, Rmax, on the depth of waviness Wt, the asymmetry Rsk, the excess Rku, on the depth of core roughness Rk and the depth of the reduced picks roughness Rpk was established. The conditions for ESD are indicated, under which the traces of the previous treatment are erased and the characteristics of the initial substrate surface are improved. The numerical values of the roughness parameters for electrospark coatings from five types of hard alloys and one type of TiB2 based electrode with nanosized additives have been established.

105-110

Authors: A. Miteva, A. Petrova, G. Stefanov

Characteristic of the samples based on Al-Si alloys, that we have studied, is their propensity for oxidation at high temperatures. The few number of papers on the oxidation kinetics of aluminium alloys associated with Planar Flow Casting technology (PFC) can be found in the literature. The oxide processes and the properties of the oxide layer formed on the aluminium alloy are mainly considered. The aim of the present work is the kinetics of oxide layer formation on aluminium alloys to clarify whether alloys are suitable for use in space and under specific conditions. The formal kinetics of Nikitin was applied for data processing. The influence of the alloying elements on the formed surface oxide coating is shown.

124-131

Authors: I. Ramadan, M. Tănase

The study on the tubes (made of CuZn36 material) of a condenser used in petrochemical industry revealed that thickness reduction by corrosion is the main factor causing the decrease of the equipment service life. The present paper aims to study, from the experimental point of view, the behavior of the heat exchanger tubes, in the presence of different environments. The experimental program conducted in the article included two directions: evaluation of technical condition of in-service brass tubes after a certain period of operation for a condenser used in petrochemical industry in order to see how the working conditions affect the brass tubes and an experimental study based on simulation of exposure to extreme corrosive environments for samples taken from new CuZn36 tubes. The goal is to establish their influence on the tubes degradations by determining the corrosion rate. The analyzed samples were immersed in different corrosive solutions for 21 days. Another sample was boiled in water and cooled in air in order to simulate the working environment of the tubes in the condenser. All the samples were weighted before and after the exposure in the aggressive environment, thus establishing the corrosion rate for each of them. In order to analyze from mechanical point of view the influence of the environment on the brass tubes, the flattening test was made, comparing the behavior of the exposed samples with that of the unexposed sample.

47-53

Authors: V. A. Kalhapure, H.P. Khairnar

The friction pair, disc, and pad in a braking system are in a delicate balance, with the pad being a complex combination of constituents that provides predictable characteristics, including a known and consistent friction level. In this investigation, L25 orthogonal array with arranged control factors is used for the design of experiment. Taguchi design, orthogonal array, S/N ratio and variance analysis (ANOVA) are used to explore the effect of factors like applied load, sliding speed and track or interface diameter on wear rate of brake pad friction material. In dry sliding conditions, wear tests are performed on the pin‐on‐disc tribometer with different load values (25-125 N), sliding speeds (300‐1500 rpm) and track diameter values (40‐120 mm). ANOVA results stated that applied load is the most effective with 48.27 %, track diameter is 25 % and sliding speed is 19.23 % on wear rate of pad friction material. In order to obtain the minimum friction material wear rate, the optimum operating parameters have been identified as applied load is 25 N, sliding speed 1500 rpm and track diameter 60 mm. The computed and experimental values for pad material wear rate are adhere closer to 1.93 % of deviations only.

62-68

Authors: B. Novaković, E. Desnica, Lj. Radovanović, R. Ivetić, L. Đorđević, D. Labović Vukić

The research in this paper aimed to show the importance of axial alignment on the example of maintaining a technical system. In this paper, the importance of alignment is examined on industrial fans. The technical system on which the alignment was performed reached the anticipated bearing life of 23,650 operating hours prescribed by the manufacturer, while the technical system on which the alignment was not performed was exposed to excessive load by a misalignment shaft. As a result, it did not meet the expected technical expectations, and it canceled at 5,400 hours of work. Research has shown that the application of alignment can increase the service life of bearings by 4.38 times on axles on which no alignment has been performed. Implementation of modern maintenance concepts, using appropriate methods of technical diagnostics aim to optimize the operation of industrial systems for a short period of time and with as few downtimes as possible. The authors of the paper presented the method of laser alignment in order to bring the industrial fan system into optimal operation. In addition to laser alignment, the condition of the system was checked by vibro diagnostics, before and after access by laser method. The paper presents all measurements performed with vibration analysis devices as well as a visual display of the state of the system during the laser alignment check of an industrial fan. Misalignment leads to incorrect operation, which in the case of electric motors and fans is most often reflected in damage in the form of distortion of the shaft or damage to the bearings.

80-87

Authors: S. Starcevic, S. Savic, N. Filipovic, A. Milovanovic, M. Djordjevic

The main purpose of this study was to reconstruct 3D aorta models based on a series of 2D CT images of two patients suffering from an aneurysm. After the 3D models had been made, a numerical solution of the problem of the abdominal aortic aneurysm was obtained. The numerical solution incorporated mathematical models of biomechanical systems. Various parameters such as shear stress, pressure, and velocity of fluid through blood vessel could be calculated using these methods. The first part of the paper introduces the abdominal aorta and aneurysm. The second part of this paper describes the process of getting 3D model geometries of the aortic aneurysms. Finally, the results obtained from the models are discussed with the aim of predicting a rupture of an abdominal aortic aneurysm and selecting the right treatment for this disease.

1-10

Authors: B. Kumar, S. K. Verma, S. Srivastava

The present work focuses on the effect of nozzle collar exit inclination on the mixing characteristics of Mach 1.76 jet in both design and off-design conditions using commercial software package ANSYS Fluent. In order to maintain the uniform Mach number at the nozzle exit, a collar is inserted at the nozzle exit and collar exit is varied with bevel angle of 300, 450 and 600 to see the effect of bevel collar on the jet mixing. Thus, four model namely C30 (300 bevel), C45 (450 bevel), C60 (600 bevel) and collar with zero bevel angle (UJ) are constructed for investigation. From the obtained results, it is reported that the bevel collars efficiently reduce the jet core as much as 76%, indicating enhanced jet mixing and found effective in both design and off-design condition of the jet. The C60 jet shows highest jet mixing followed by C45 jet, C30 jet and UJ. Thus, increase in bevel angle led to increase in mixing enhancement of the jet. Due to asymmetry in collar, the upward and downward shift of the jet core are seen with variation in NPR for the controlled jets (C30, C45 and C60).

21-28

Authors: S. Mulahasan, A. Y. Mohammed

Flow-through a bridge opening may run either partially or fully. In this research, backwater rise, hydraulic loss coefficient, and drag coefficient for two bridge models and three flow conditions are investigated. Based on the dimensional analysis theory, an equation was developed to calculate the water level difference Δh between the upstream and the downstream for the bridge models. Results showed that the derived equation of the backwater rise is valuable to the experimental data which showed a percentage error not exceed 5%. The hydraulic loss coefficient CL and the drag coefficient CD were calculated. The drag coefficient values for the lateral constriction models are ranged from 0.5 to 2.0, and for the submerged bridge, the model was in the range of (0.5-3.5) with an average of 2.1. The impact of the blockage ratio on the hydraulic loss coefficient showed an increase of 1-2 times when the blockage was changed from 0.70 to 0.483.

39-45

Authors: M. Embiale, A. Bekele, C. Venkatachalam, M. Parthiban

In this paper, the velocity and pressure drop distribution in flowing water through circular, square, rectangular with aspect ratio of 2:1 and 4:1 as well as an equilateral triangle cross-sectional ducts with the same duct length and hydraulic diameter have been numerically studied using ANSYS FLUENT tools. The boundary conditions used for the simulation are: at the entrance a velocity inlet of 0.2 m/s at 25 oC constant temperature, at exit a pressure outlet with zero gage pressure and a non-slip is used for the duct walls condition. A steady state and kepsilon turbulence flow model is used. The results have shown that velocity in the ducts gradually increases from zero at the walls to the maximum at the center. In the circular duct 20.327%, 15.273%, 13.5% and 6.834% more pressure is lost than in triangular, square, rectangular aspect ratio of 2:1 and rectangular aspect ratio of 4:1 ducts respectively. In turn, circular duct requires the highest pumping power while triangular one needs the lowest.