Numerical Analysis of Air Flow Over Buildings for Renewable Energy Application in Bangladesh

Bangladesh is a developing country in South Asia. Dhaka is the capital and largest city, followed by Chittagong. Bangladesh is the world’s eighth most populous country. The rate of population here is growing day by day. Also, there is lack of accommodations as well as lack of lands. Therefore, many unplanned dense buildings which are constructed in an unplanned manner. Despite this unavoidable condition these buildings can be utilized as the source of power generation. The power generated in our country is not sufficient to cover all the regions. In addition, the pollution is growing sharply with the increase of industrial advancement. This requires to reduce the environmental impact as much as possible. Demand is always higher than the production. To meet up the demand, building-integrated micro-wind turbines are suggested to install on the roof of commercial as well as residence structures to generate energy. Wind turbine power of a wind generator [1] can be expressed as follows:

P_Turbine=1/2 ρC_p AV^3

Where, P_Turbine is the wind turbine power, ρ is the air density(kg⁄m^3 ), C_p is the co-efficient of performance, A is the swept area of the blades (m^2) and V is free wind speed (m/s). From the above equation, it is showed that the power of the wind increases with the cube of the wind speed.

On the other hand, the rate of carbon emission is rising day by day. An expansion in the degree of public awareness regarding the effect of Green House Effect on the nature and the detrimental effect of our dependency on fossil fuels has acquired a developing enthusiasm on site-generated electricity from sustainable energy sources. Therefore, use of fossil fuels should be reduced to lessen environmental damage. Hence, if we focus on alternative energy solutions, it will reduce our carbon footprints.

However, a case study is important to identify suitable locations to mount wind turbines where maximum efficiency can be utilized. The residential areas where the alignment of the buildings is similar and gap between buildings are standard are eclectic for the construction of wind turbines (Horizontal or Vertical). Besides, the environment should be such that where under average condition, the wind speed is at least 3-4 meters per second (m/s). Most wind turbines start generating electricity at wind speeds of around 3-4 m/s (8 miles per hour) [2]. Bangladesh Meteorological Department has done statistics on different places monthly and given annual results on that basis [3]. Statistics shows, on the month of June and July, Chittagong has the highest wind speed of around 8.7 m/s. On the other hand, Jessore possesses the wind speed of 6 m/s on April and May. Similarly, Cox’s Bazar has same type of wind speed, but on June and July. Dhaka, Sayedpur and Comilla have the same kind of wind speed on April, May.