Wind energy is being considered all over the world due to the clean characteristics that it posse... more Wind energy is being considered all over the world due to the clean characteristics that it possesses and prevalent virtually everywhere in the world. With the current existing technology, a wind turbine could only harness a small portion of energy from the available wind. The amount of harnessed energy could be significantly decreased, if proper wind energy assessments (i.e. micrositing, geographical condition, wind regime characteristics, etc.) were not performed carefully and effectively. As previous studies have shown that, most of the projects which seem to be unfeasible were due to environmental problems such as appropriate site selection, and not technological problems such as wind turbine design. This study presents and discusses the main factors to be considered when undertaking wind energy project in any potential site, so that significant amount of energy could be harvested.
Pressure Drop and Heat Transfer Characteristics of Louvered Fin Heat Exchangers
Applied Mechanics and Materials, 2013
This paper presents the effect of the changes in fin geometry on pressure drop and heat transfer ... more This paper presents the effect of the changes in fin geometry on pressure drop and heat transfer characteristics of louvered fin heat exchanger numerically. Three dimensional simulation using ANSYS Fluent have been conducted for six different configurations at Reynolds number ranging from 200 to 1000 based on louver pitch. The performance of this system has been evaluated by calculating pressure drop and heat transfer coefficient. The result shows that, the fin pitch and the louver pitch have a very considerable effect on pressure drop as well as heat transfer rate. It is observed that increasing the fin pitch will relatively result in an increase in heat transfer rate but at the same time, the pressure drop will decrease. On the other hand, low pressure drop and low heat transfer rate will be obtained when the louver pitch is increased. Final result shows a good agreement between experimental and numerical results of the louvered fin which is about 12%. This indicates the capabilit...
This study presents an overview on the possibilities of interior noise reduction for monorail sys... more This study presents an overview on the possibilities of interior noise reduction for monorail system using passive means. Nine samples out of three materials were subjected for noise test and the performance of each sample was observed. It is found that all of these samples have proved to reduce a significant amount noise at low and high frequencies even though the amount reduced differ from one sample to another. It is also been noticed that this reductions were denominated by means of absorption for some samples such as those from rubber material, and it was dominated by means of reflection for some others such as those from aluminum composite and paper composite. Moreover, from these different acoustic properties of each material, the whereabouts to install every material is different as well. It was suggested that, the rubber material should be installed on the upper floor of the monorail while, the paper composite should be installed under floor, and the aluminum composite shou...
The Savonius wind turbine is considered as one of the solutions for harvesting the kinetic energy... more The Savonius wind turbine is considered as one of the solutions for harvesting the kinetic energy from the wind in the urban areas, due to magnificent features such as, low construction cost, high starting torque, and self-starting ability especially at low wind speed. However, the conventional rotor suffers from low efficiency. Thus, modifying the configuration of the rotor may be an effective solution for providing electricity to the communities with no access to the power grid. Thus, this investigation aims to study numerically the effect of adding two inner blades on the performance of the Savonius wind rotor at low tip speed ratios (TSRs). The simulations are carried out using the two-dimensional simulation with the assist of ANSYS software. For turbulence modelling, the K-ε/realizable model was adopted in this study. Power coefficient (C p) and torque coefficient (C t) at various TSRs for the rotor are determined under a constant external overlap of 0.018 m. Furthermore, the effect of space between the inner blades was also investigated using three values of spacing. The simulation results show that the rotor with two inner blades performs better than the same rotor without inner blades at all tested TSRs expect at low considered values of 0.2 and 0.25. The heights Cp was 0.188 with 17.1% performance improvement at TSR = 0.4. Furthermore, the numerical results show that C p values decrease with the decrease of the space between the blades.
Journal of Advanced Research in Fluid Mechanics and Thermal Sciences, 2021
The use of solar thermal technologies has shown great prospects towards solar energy conversion i... more The use of solar thermal technologies has shown great prospects towards solar energy conversion into more useful forms of energy and has increasingly expanded solar thermal technology applications. However, the inability to properly store the excess solar energies during peak hours and demands have limited many of their applications. The integration of thermal energy storage (TES) systems with thermal technologies have increased the solar thermal technology performance but the poor thermal characteristics exhibited by phase change materials (PCM) limited the system overall performance. The enhancement of PCM properties by nonadditive have shown increased material performance in TES application and thereby extending the use of solar thermal technology application. Given this narrative and identifies literature gaps, the present study investigated experimentally the enhancement of paraffin PCM using nonadditive metallic of different types and concentrations and analysed their thermal ...
International Journal of Integrated Engineering, 2019
Wind energy technology is one of the fastest growing alternative energy technologies. However, co... more Wind energy technology is one of the fastest growing alternative energy technologies. However, conventional turbines commercially available in some countries are designed to operate at relatively high speeds to be appropriately efficient, limiting the use of wind turbines in areas with low wind speeds, such as urban areas. Therefore, a technique to enhance the possibility of wind energy use within the range of low speeds is needed. The techniques of augmenting wind by the concept of Diffuser Augmented Wind Turbine (DAWT) have been used to improve the efficiency of the wind turbines by increasing the wind speed upstream of the turbine. In this paper, a comprehensive review of previous studies on improving or augmentation power of horizontal axis wind turbines (HAWT) have been reviewed in two categories, first related with relative improvement of energy by improving the aerodynamic forces that affecting on HAWT in some different modifications for blades. Second, reviews different techniques to the augment the largest possible amount of power from HAWT focusing on DAWTs to gather information, helping researchers understand the research efforts undertaken so far and identify knowledge gaps in this area. DAWTs are studied in terms of diffuser shape design, sizing of investigation and geometry features which involved diffuser length, diffuser angle, and flange height. The conclusions in this work show that the use of DAWT achieves a quantum leap in increasing the production of wind power, especially in small turbines in urban areas if it properly designed. On the other hand, shrouding the wind turbine by the diffuser reduces the noise and protects the rotor blades from possible damage.
The present paper aims to study the possibility of dispensing an auxiliary power unit (APU) in an... more The present paper aims to study the possibility of dispensing an auxiliary power unit (APU) in an aircraft powered by fossil fuels to reduce air pollution. It particularly seeks to evaluate the amount of power generated by the ram air turbine (RAT) using the novel counter-rotating technique while characterizing its optimum axial distance. The ram air turbine (RAT), which is already equipped in aircrafts, was enhanced to generate the amount of energy produced by the APU. The approach was implemented by a CRRAT system. Six airfoil profiles were tested based on 2D models and the best airfoil was chosen for implantation on the RAT and CRRAT systems. The performance of the conventional single-rotor RAT and CRRAT were analyzed using FLUENT software based on 3D models. The adopted numerical scheme was the Navier–Stokes equation with k–ω SST turbulence modeling. The dynamic mesh and user-defined function (UDF) were used to revolve the rotor turbine via wind. The results indicated that the F...
Sustainable Energy Technologies and Assessments, 2019
Darrieus H-rotor has gained much interest in the last few decades as among the reliable devices f... more Darrieus H-rotor has gained much interest in the last few decades as among the reliable devices for wind energy conversion techniques for their relatively simple structure and aerodynamic performance. This study presents a numerical investigation of a novel vertical axis wind turbine (VAWT) with a contra-rotating concept. The aim is to reveal the effectiveness of this concept on enhancing the performance of the turbine as it has yet to be applied to a VAWT system. The simulations were performed using three-dimensional computational fluid dynamics (CFD) models based on K-omega shear stress transport (SST) turbulence model. This computational study covers a wide range of simulation work including a parametric study based on the axial distance between the two rotors and rotor aspect ratio. It was found that the new concept works more efficiently and therefore the performance of the turbine has been improved significantly. The system was capable of producing more than double of torque coefficient compared to a single-rotor system of a similar type. The results also indicate that smaller axial distance tends to enhance the performance output of the system relatively better compared to a larger distance. In terms of rotor aspect ratio, bigger aspect ratio generated the highest amount of power.
IOP Conference Series: Materials Science and Engineering, 2016
The new Kuala Lumpur Monorail Fleet Expansion Project (KLMFEP) uses semiactive technology in its ... more The new Kuala Lumpur Monorail Fleet Expansion Project (KLMFEP) uses semiactive technology in its suspension system. It is recognized that the suspension system influences the ride quality. Thus, among the way to further improve the ride quality is by finetuning the semi-active suspension system on the new KL Monorail. The semi-active suspension for the monorail specifically in terms of improving ride quality could be exploited further. Hence a simulation model which will act as a platform to test the design of a complete suspension system particularly to investigate the ride comfort performance is required. MSC Adams software was considered as the tool to develop the simulation platform, where all parameters and data are represented by mathematical equations; whereas the new KL Monorail being the reference model. In the simulation, the model went through step disturbance on the guideway for stability and ride comfort analysis. The model has shown positive results where the monorail is in stable condition as an outcome from stability analysis. The model also scores a Rating 1 classification in ISO 2631 Ride Comfort performance which is very comfortable as an overall outcome from ride comfort analysis. The model is also adjustable, flexibile and understandable by the engineers within the field for the purpose of further development.
An aerodynamic performance analysis of a perforated wind turbine blade
IOP Conference Series: Materials Science and Engineering, 2016
Wind power is one of the important renewable energy sources. Currently, many researches are focus... more Wind power is one of the important renewable energy sources. Currently, many researches are focusing on improving the aerodynamic performance of wind turbine blades through simulations and wind tunnel testing. In the present study, the aerodynamic performance of the perforated Eqwin blade (shell type blade) is investigated by using numerical simulation. Three types of slots namely circular, horizontal rectangular and vertical rectangular were evaluated. It was found that the optimum angle of attack for a perforated shell type blade was 12° with maximum Cl/Cd value of 6.420. In general, for all the perforated blade cases, Cl/Cd tended to decrease as the slot size increased except for the circular slot with 5 mm diameter. This was due to the disturbance of the airflow in lower side region which passed through the bigger slot size. Among the modified slots; the circular slot with diameter of 5 mm would be the best slot configuration that can be considered for blade fabrication. The Cl/Cd obtained was 6.46 which is about 5% more than the value of the reference blade. Moreover, the introduced slot would also reduce the overall weight of the blade by 1.3%.
In the present work, development and aerodynamic performance prediction of a unique contra-rotati... more In the present work, development and aerodynamic performance prediction of a unique contra-rotating vertical axis wind turbine (VAWT) have been studied. The purpose of this paper is to investigate the effectiveness of employing the contra-rotating concept to a VAWT system while enhancing its conversion efficiency. The performance evaluations of the current model were established in terms of key aerodynamic performance parameters such as power, torque, power coefficient and torque coefficient. The systematic analysis of these quantities showed the effectiveness of the contra-rotating technique on VAWT system and the ability to extract additional almost threefold power over the entire operating wind speed ranges covered. The system has also improved the inherent difficulties of the Darrieus rotor to self-start. Moreover, the results of the new concept also demonstrated a significant increase in terms of conversion efficiency for both power and torque compared to a single-rotor system of a similar type. It is anticipated that this current approach will revolutionize wind energy harvesting strategies and will find application in a wide range of wind turbine sites that are characterized by relatively low and moderate wind speed regimes and particularly be useful in the urban environment where turbulence intensity is high.
Assessment of wind energy potential in the capital city of Chad, N’Djamena
AIP Conference Proceedings, 2017
In this study, statistical analysis of a long term meteorological data of 10 years have been pres... more In this study, statistical analysis of a long term meteorological data of 10 years have been presented to reveal the potential of wind power as a source of energy generation in the capital of Chad, N’Djamena. The recent ten-year period wind data were collected from the Hassan Djamous International Airport at N’Djamena. The wind characteristics and wind energy potential were analyzed using Weibull distribution function. The results show that the values of the shape parameter k, and scale parameter c, varied over a wide range. The annual highest values of the Weibull shape parameter k, and scale parameter c, were 1.59 and 4.12 m/s respectively. It was also found that higher wind speeds occurred during dry season, i.e. November to July and the lower wind speeds occurred during the wet season, i.e. August to October. The annual average of the most probable wind speed and wind speed carrying maximum energy were respectively 1.86 m/s and 6.48 m/s. Likewise, the wind power density was ranging between 55.96 W/m2 ...
Numerical study using ANSYS Fluent is conducted to investigate the effects of louver angle on pre... more Numerical study using ANSYS Fluent is conducted to investigate the effects of louver angle on pressure drop and heat transfer of a heat exchanger. Flow simulations are conducted on 3D modeling of multi stacks louvered fins at three different parameters of louver angles which are 22.0o, 25.5o and 29.0o with Reynolds number ranging from 200 to 1000. These Reynolds numbers are based on louver pitch and fin pitch. The flow temperature is set at 300K which is the room temperature, while temperature of louver fin is set at 400K. The results show that Reynolds number based on fin pitch 2.02 mm and louver angle of 22.0o generate higher performance of heat exchanger compared to louver pitch of 1.40 mm and the other louver angles. Therefore, configuration of Reynolds number based on fin pitch 2.02 mm and louver angle 22.0o is preferred to be adopted in the design process of heat exchanger.
Continuing to use fossil fuels is bound to pollute the atmosphere, and consequently, unwanted gre... more Continuing to use fossil fuels is bound to pollute the atmosphere, and consequently, unwanted greenhouse and climate change effects will come to dominate every part of the earth. It is, therefore, advisable to exploit clean energy resources for many nations in the world to try to keep their environment friendly, such as wind energy. Hence, it is necessary to determine to start the immediate usage of the wind energy potential and the investigation of the necessary techniques and economic feasibility in every country. In this study, the possible wind energy potential has been investigated in K€ utahya, Turkey. In this regard, a wind observation station was established at the Dumlupınar University Main Campus, and it is examining the possible electrical power that can be generated by the wind. The data collected in this observation station between the dates of July 1, 2001 and February 28, 2003 were evaluated via the CALLaLOG 98 and ALWIN package softwares. Inside the observatory field, the measured average wind speed for a period of 20 months is 4.62 m/s for a 30 m height, while the energy density is 36.62 W/m 2. Values from the established measurements are searched to determine whether electricity can be produced from the wind energy. The mean wind speed does not provide economical electricity production from the wind energy, and the measurements should be evaluated in the long term in accordance with technological developments and reduction in the cost of turbines.
Pressure Drop and Heat Transfer Characteristics of Louvered Fin Heat Exchangers
Applied Mechanics and Materials, 2013
This paper presents the effect of the changes in fin geometry on pressure drop and heat transfer ... more This paper presents the effect of the changes in fin geometry on pressure drop and heat transfer characteristics of louvered fin heat exchanger numerically. Three dimensional simulation using ANSYS Fluent have been conducted for six different configurations at Reynolds number ranging from 200 to 1000 based on louver pitch. The performance of this system has been evaluated by calculating pressure drop and heat transfer coefficient. The result shows that, the fin pitch and the louver pitch have a very considerable effect on pressure drop as well as heat transfer rate. It is observed that increasing the fin pitch will relatively result in an increase in heat transfer rate but at the same time, the pressure drop will decrease. On the other hand, low pressure drop and low heat transfer rate will be obtained when the louver pitch is increased. Final result shows a good agreement between experimental and numerical results of the louvered fin which is about 12%. This indicates the capabilit...
Wind power is an energy source that is becoming an alternative to burning fossil fuels that may h... more Wind power is an energy source that is becoming an alternative to burning fossil fuels that may harm the environment during operations due to the emission of harmful gases. In this study, simulation and performance investigations of a counter-rotating vertical axis wind turbine (VAWT) based on the Savonius S-type rotor have been analysed through a computational simulation approach. The foremost motive of this study is to widen the operating wind speed range of the counter-rotating concept in a VAWT while enhancing the conversion efficiency of a single-rotor VAWT system. The 3D simulations were performed based on the K-omega shear stress transport (SST) turbulence model. The results have shown that the counter-rotating model possesses better performance characteristics in terms of torque, power and their corresponding coefficients compared to a single-rotor design of a wind turbine. A maximum output of more than two times was obtained from the new CRWT system compared to that of a single-rotor wind turbine (SRWT). Moreover, the output of the top rotor was higher than the bottom rotor due to the increased higher rotational speed of the top rotor.
Recently, Didane et al. [6] studied broadly the potential of wind energy in Chad while covering t... more Recently, Didane et al. [6] studied broadly the potential of wind energy in Chad while covering thirteen meteorological stations from the three main zones in the country which are the Sahara desert, the Sahel and the Sudanian zone. It was found that the potential of wind energy in Chad is promising with the Sahel and the Sahara zones seem to show the highest potentials of wind energy harvesting in the country. Soulouknga et al. [8] also carried wind assessment in the Sudanian zone in Chad. It is, however, indicated that in this zone, wind energy could be regarded as a potential alternative only at 67 m height above the ground for electricity generation, heating and
Experimental Investigation on Evacuated Tube Solar Collector Using Biofluid as Heat Transfer Fluid
Journal of Advanced Research in Fluid Mechanics and Thermal Sciences
Bio-oil extracted from waste of different plant kernel was used as heat transfer fluid in evacuat... more Bio-oil extracted from waste of different plant kernel was used as heat transfer fluid in evacuated tube solar collector. Thermal performance of the biofluids to the enhancement of the evacuated tube solar collector under varying weather conditions and experimental analysis was carried-out. Thermal analysis on the storage water tank temperature, outlet and inlet heat transfer fluid temperature, and heat gains by was studied. In addition, the biofluids thermophysical properties and degradation analysis was conducted and compared with conventional base-fluids. From the results the biofluids caused enhancement of heat gain in the collector receiver by 9.5%, 6.4% and 3.2% for moringa oleifera kernel oil (MOKO), date kernel oil (DKO) and palm kernel oil (PKO), respectively. The storage water tank temperature at night fall was 53, 49, 51 and 47oC, for the MOKO, DKO, PKO and water HTFs, respectively. The biofluids were thermal stable and with no degradation. The biofluids demonstrated pote...
Performance of Double Blade Savonius Rotor at Low Rotational Speed
Journal of Computational and Theoretical Nanoscience
The performance of the single and double blade Savonius rotors are numerically analyzed using the... more The performance of the single and double blade Savonius rotors are numerically analyzed using the K-ε/realizable turbulence model. The computations are implemented at different values of tipspeed ratio from 0.2 to 0.4 with a step of 0.05. Both rotors have the same dimensions with an external overlap between their blades equals 0.02 m. The results indicate that the double blade rotor performs better than the single blade rotor in terms of power coefficient. In addition, the torque coefficient is improved at all tested values of tip-speed ratio. Furthermore, the results of the simulation show that the maximum power coefficient was 0.163 at tip-speed ratio = 0.4 for the double blade rotor, whereas the maximum improvement of the double blade rotor occurs at tipspeed ratio = 0.2 with a percentage of 11.86% compared to the single blade rotor. Moreover, the highest value of the torque coefficient was 0.524 at tip-speed ratio = 0.2 for the double blade rotor.
Uploads
Papers by Djamal Didane