Design of Stormwater Particle Removal System for Small-Scale Urban Hydropower based on the Vortex and Coandă Effects

Abstract

Abstract-Small hydropower systems are a future concept for urban regeneration development. Such a system should function properly under tropical conditions, where rainfall is especially abundant. To implement a small-scale urban hydropower system, a special design is needed to handle diverse sedimentary sizes and deposition characteristics of particles in stormwater, which if unattended may disrupt the functioning of turbine-generator components. Combining the effects of stormwater vortex and Coandă was previously suggested to enhance particulate removal efficiency. This paper was prepared based on this concept. The paper specifically aims to quantify the design parameters which are vital for a high removal efficiency system. These optimal design parameters are also presented in detail in this paper.Keyword [5]. Previous studies have highlighted the need to modify the detention outlet to ensure constant flow rates for a more efficient small-scale urban hydropower system [5]. In this paper, stormwater infrastructure refers to a detention pond which could be used for developing small-scale urban hydropower.Specific challenges to the implementation of small-scale urban hydropower systems include stormwater quality and flow fluctuation. In terms of stormwater quality, the infinite variety of sedimentary sizes and deposition characteristics complicate the design of a detention outlet. Stormwater particles range from coarse grains to silts, and are highly dependent on site topography. It is therefore necessary to design a new and unique system that can handle these stormwater particulate varieties. A clean stormwater source is needed for energy generation purposes to avoid problem on turbine erosion which may reduce the performance of energy generation. For example, in big hydropower system, treatments such as screen intake are used to filter large particles from entering the turbine and generator components.Two theories about vortex and Coandă had been investigated in order to ensure the applicability of the effects for removing the particles in stormwater. These effects also may help cope with the fluctuation of water. Vortex effects had been applied in the hydrocyclone and may easily remove fine particles by using centrifugal force especially when the high velocity is observed [6], [7], [8], [9] and [10] Coandă effects had been well applied in aerodynamic design [11], hydropower [12] and stormwater system [13]. Coandă may help to remove light and coarse particles and could regulate the flow water based on its optimized slope condition. In referring of above challenges, one possible solution is to utilize combined effects of stormwater Coandă and vortex, which may not only solve particulate problems, but also stabilize stormwater flow rate. It nevertheless remains imperative to assure clean water source for a small-scale urban hydropower system.The authors therefore proposed a new system designed based on the combined effects of vortex and Coandă, which should be in particular practical for tropical countries with...