by Sobhi Frikha, Zied Driss, Hedi Kchaou and Mohamed Salah Abid
Original Research
This study aims to investigate the effect of the incidence angle on the aerodynamic characteristics of the flow around a Savonius wind rotor. Six configurations with different incidence angles equal to θ=0°, θ=30°, θ=60°, θ=90°, θ=120° and θ=150° were studied. For this, we have developed a numerical simulation using the Computational Fluid Dynamic (CFD) code "Fluent". The considered numerical model is based on the resolution of the Navier-Stokes equations in conjunction with the k-ε turbulence model. These equations are solved by a finite volume discretization method. Particularly, we are interested in visualizing the velocity field, the mean velocity, the static pressure, the dynamic pressure, the turbulent kinetic energy, the dissipation rate of the turbulent kinetic energy and the turbulent viscosity. Results confirm that the variation of the incidence angle has an effect on the local characteristics. Our numerical results were compared with those obtained by anterior results. The comparison shows a good agreement and confirms the numerical method.
American Journal of Energy Research. 2016, 4(2), 42-53. DOI: 10.12691/ajer-4-2-3
Pub. Date: September 12, 2016
22098 Views5051 Downloads1 Likes1 Citations
by Md Rokonuzzaman, Sharmin Jahan and Md Shahidul Haque
Original Research
Introduction: Electricity is a necessity in the modern world. Electricity has attained a very important place in every household on this planet. It is a major contributor towards improvement of the standard of living of any individual, family and society at large. The aims of this study is to find out the monthly average household electricity consumption and fit a suitable time series model to predict the electricity use. Data and Analysis: A time series monthly electricity uses data of a middle class family in Chittagong from January 2001 to November 2015 is considered in this analysis. To check variability the descriptive statistics and different types of graphs are used. The volatility model ARCH family regression with ARIMA disturbances model is used for forecasting. Chow test statistic is used for checking the structural breaking point of the dataset. Results & Conclusion: From the ACF and PACF function we get the cut off point for AR and MA part are 2 and 3 respectively. Further as ARCH effect is significant for this data set we use ARCH family regression with ARMA disturbances model, After comparing the different value of the parameters, ARCH(1) with ARIMA (3,0,2) disturbances is best fit for this data set. There have a structural break point for the month of December in 2010. Before this date data, ARCH (1) regression family with ARIMA (2,0,2) disturbance is the best fitted model for the analysis. And for the post data follows only ARIMA(1,0,1) disturbance is the best fitted model for this analysis. Recommendation: For forecasting of the monthly electricity uses of a middle class family in Chittagong, ARCH(1) with ARIMA (3,0,2) disturbances time series model can be used. For better prediction one can consider to select a representative size of sample families with at least 20 years data. Also some covariates like family size and electronic items used in the family can be considered and can try to fit a GARCH or TGARCH model.
American Journal of Energy Research. 2016, 4(2), 35-41. DOI: 10.12691/ajer-4-2-2
Pub. Date: August 03, 2016
17418 Views4092 Downloads2 Likes
by I. M. Kuzmenko and O. V. Makarchuk
Original Research
Mass transfer coefficient for contacting conditioning is determined experimentally and theoretically for steady air. Contribution of diffusion and convection component into mass transfer is estimated. The assessment showed that the contribution of the convection component into mass transfer can be neglected. Thickness of diffusional mass transfer layer was experimentally measured and it less than the theoretical values of displacement layer thickness till 10 times. Therefore the experimental value of mass transfer coefficient exceeds by one order the theoretically calculated ones. The criteria equation is recommended for calculation of mass transfer coefficient at steady air flow in a channel.
American Journal of Energy Research. 2016, 4(2), 27-34. DOI: 10.12691/ajer-4-2-1
Pub. Date: August 03, 2016
18210 Views4032 Downloads