Experimental and simulation study on the aerodynamic performance of a counter rotating vertical axis wind turbine

The 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. In the present work, development and aerodynamic performance predictions of a unique contra-rotating VAWT have been studied through experimental and computational approaches as it has yet to be applied to a VAWT. The main purpose of this study is to develop and investigate the practicality of employing the contra-rotating concept to a VAWT system while enhancing its conversion efficiency. The simulation study was performed using three-dimensional computational fluid dynamics (CFD) models based on K-omega shear stress transport (SST) model. The computational work covers a wider range of simulation processes compared to the experiment which includes a parametric study based on the axial distance between the two rotors and blade height. The performance evaluations of the current models were established in terms of key aerodynamic parameters such as torque and power. The systematic analysis of these quantities showed the usefulness of the contra-rotating technique on a VAWT system and the ability to extract additional more than threefold power over the entire operating wind speeds covered. The system has also improved the inherent difficulties of the Darrieus rotor to self-start. The results 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. A maximum of 43% and 46% of power and torque coefficients were respectively possible with the current dual-rotor system. The simulation results indicate that smaller axial distance tends to enhance the performance output of the system relatively better compared to a larger distance. However, in terms of the blade height, longer blades generated the highest amount of power. It is anticipated that this current technique could revolutionize wind energy harvesting strategies and would find applications in a wide range of sites that are characterized by low and moderate wind regimes and particularly be useful in the urban environment where turbulence is high

Wind and Solar Assessment in the Sahelian Zone of Chad

Renewable energy sources have long been renowned as potential sources of free, clean and inexhaustible energy. However, energy in Chad is still exploited from non-renewable sources due to lack of comprehensive wind and solar maps, skills and public awareness pertaining to its significance in the country. This study is therefore set out to provide assessments of both wind and solar energies in the Sahelian zone in Chad, using the statistical two-parameter Weibull distribution function and Angstrom-Prescott model, respectively for a ten-year period. The evaluation of wind potential shows that the annual mean of the shape and scale parameters for all stations under study varied in the range of 1.26 – 1.56 and 2.49 m/s – 3.91 m/s, respectively. Stronger wind speed was observed during the dry season and a relatively slower wind speed was perceived during the wet season. Among the four stations, N’Djamena showed the highest power density compared to the other three stations with a mean power density that ranges between 100 W/m2 – 220 W/m2. The prediction of solar potential in this region indicates that the global solar radiation for all stations is promising with station Abeche however, to show the highest solar energy density on average. A good agreement between Angstrom model and NASA data was also observed. Â

Properties and environmental impact from mosaic sludge industry incorporated into fired clay bricks

Brick is one of the most common masonry units used as building material. Due to the demand recently, different types of waste materials have been investigated to be incorporated into bricks. The utilization of these waste materials in fired clay bricks usually has positive effects on the properties such as lightweight bricks with improved shrinkage, porosity, and strength. The main objective of this study is to focus on the properties and environmental impact of the mosaic sludge incorporated into fired clay bricks. The characteristics of raw materials obtained by using the XRay Fluorescence Spectrometer showed that the chemical composition of the raw materials of clay soil and mosaic sludge was high with silicon dioxide and aluminium oxide and with the same chemical composition BS and PS are suitable to replace clay soil as raw materials. The recommended percentage of BS and PS incorporation was up to 30% with better physical and mechanical properties. The results showed that the utilization of BS and PS brick obtained higher compressive strength up to 25 N/mm2 and low initial rate of suction under the limit of 5 g/mm2. The leachability tests such as Toxicity Characteristic Leaching Procedure (TCLP), Synthetic Precipitation Leaching Procedure (SPLP) and Static Leachate Procedure (SLT) were conducted to determine the results which complied with the United State Environment Protection Agency (USEPA) and Environment Protection Agency Victoria (EPAV). As for the indoor air quality, BS sludge and PS sludge could be incorporated up to 30% in the fired clay bricks for good physical and mechanical properties that complied standard requirements for heavy metals with better indoor air quality based on the Industry Codes of Practice on Indoor Air Quality (ICOPIAQ) standards. Therefore, BS and PS wastes can be an alternative low cost material that provides an environmentally friendly disposal method

Assessment of wind energy potential at Gong Kedak and Pantai Chendering, Malaysia

Nowadays, moving toward renewable energy sources is a crucial step in planning for any country’s economic growth and in determining the viability of any wind development project. Since independence, Malaysia has spent significant resources on increasing its energy capability. As a result, the country’s generation capacity has increased substantially. Wind energy is increasingly being accepted as a significant complementary energy source for securing sustainable and clean energy for the future in Malaysia. However, comprehensive wind energy assessments at some potential sites of the country are still not discovered. Therefore, this stuy is set out to provide assessments of wind energy potentiality at the Gong Kedak in Kelantan and the Pantai Chendering in Terengganu using the 2-parameter Weibull distribution. The recent two years’ period wind speed data of 2019 and 2020 used in this analysis were collected from the wind monitoring station of the Malaysian Meteorological Department. The maximum Weibull parameters (k, c) were 2.64 and 5.21 m/s, and both acted at Pantai Chendering. The Maximum mean wind energy in Pantai Chendering was 7.9 m/s, but the highest at Gong Kedak was only 2.1 m/s over two years period. Gong Kedak recorded 14.68 kWh/m2 in wind energy density, whereas Pantai Chendering recorded 660.29 kWh/m2 . The result presented as a Weibull distribution and analysis indicated that the station at Pantai Chendering has tremendous potential. However, the wind power potential in the site covered in the present study is only adequate for small-scale wind energy applications

Assessment of solar energy potential in Johor, Malaysia

Solar energy is one of the well-known renewable energy sources from sunlight that convert to free-pollution energy. One of the major development problems for developing countries is the energy dilemma. The energy problem is considered a significant obstacle to economic development. In the current situation, solar energy can be considered one of the safest options. This paper presents the assessment of solar energy potentials at nine stations in Johor, Malaysia for a five-year period stretching between 2015 and 2020. The assessment data for all stations were obtained from the Malaysian meteorological department. The meteorological parameters involved include temperature, extraterrestrial solar radiation and clearness index. The assessment technique involved the use of the Angstrom-Prescott (A-P) model to estimate the solar energy potentials at the sites. From the results obtained from the A-P model, it is apparent that Station Segamat has the highest average monthly global solar radiation on the horizontal surface with 6.7921 kWh/m2 monthly solar radiation, while Pontian station has the lowest with 6.7893 kWh/m2 monthly solar radiation. The monthly clearness index throughout the year in each station varies between 0.65 to 0.7 and the maximum temperature ranges from 22.71°C at Pontian station to 32.42°C at station Kota Tinggi. Based on the comparison and analysis of the results, it is clear that each station at Johor has an excellent solar energy potential and is suitable for photovoltaic module system application

Performance investigation of vertical axis wind turbine with savonius rotor using Computational Fluid Dynamics (CFD)

The quest of clean and sustainable energy has grown rapidly all over the world in the recent years. Among the renewable energy resources available, wind energy is considered one of the reliable, environmentally friendly, green and fastest-growing source of electricity generation. This generation is accomplished through wind turbines. However, the efficiency of these wind turbines is still very limited and unsatisfactory. The primary goal of this study is to evaluate the performance of a Savonius rotor wind turbine in terms of aerodynamic characteristics, including torque, torque coefficient, and power coefficient. The design of Savonius wind turbine blades is varied and its effects is observed. The simulation models are developed using a modeling software known as Solidworks 2021 and then generated into Ansys Design Modeler 2021 R1 to define the fluid domain. In total, three distinct turbine blades are modelled while varying the diameter and height of the rotor. The simulation study is performed using FLUENT 2021 R21. A constant wind speed value of 9.2 m/s has been used throughout the simulation. The simulation was carried out using a transient time flow with a constant upstream wind speed. The results have shown that the power coefficient of all models increases with TSR and the highest efficiency is consensually obtained at almost a unity (0.9) TSR. Comparing the performance of all models, Model 2 generates the highest power coefficient followed by Model 3 and Model 1, respectively. In terms of power, torque and torque coefficient, nearly similar conclusion is drawn

Wind as a sustainable alternative energy source in Malaysia - a review

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

Wind energy assessment as a source of power generation in Bangladesh

Wind energy has been considered one of the most popular forms of renewable energy. It has been widely considered for the generation of electricity for its low maintenance cost and negligible effect on environmental pollution. The purpose of this research is to evaluate and compare the wind energy potential in seven different districts of Bangladesh including Barisal, Chittagong, Dhaka , Khulna, Rajshahi, Rangpur, and Sylhet. Data had been recorded on daily basis for the consecutive five years from 2015 until 2 019 and analysed using Weibull distribution function various essential parameters such as wind speed, wind energy density and wind power density. Results show that the monthly average wind speed varies between 0.5 m/s to 2.10 m/s for all the divisions except Chittagong where it is in the range between 3 m/s and 4.5 m/s. Similarly, the maximum wind power density and wind energy density were also found in the Chittagong division with annual densities that range between 51.86967 W

Effects of geometrical parameters to the performance of louvered fin heat exchangers

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

Direct torque control induction motor drives

This paper presents an implementation of a direct torque control (DTC) strategies to control the operation induction motor (IM). The aim is to control effectively the torque and flux. Torque control of an induction motor base on DTC strategy has been developed and a comprehensively study in this thesis. Direct torque control is the first technology to control the real motor control variable of torque and flux. This method made the motor more accurate and fast torque control, high dynamic speed response and simple to control. This report presents a principle of the DTC; switching table, and selection of the amplitude of the hysteresis band of torque and flux. The basic dynamic performance of DTC is investigated. The performance is including in when the motor in starting drives and when motor in nominal value. The performance of this control method has been demonstrated by simulation using a versatile simulation package, MATLAB/SIMULINK. The author also present the simulation results related to the theoretical aspects mentioned in the paper. The result shows that the proposed direct torque control is capable to control the operation of the induction moto