Abstract
Using a pump in reverse mode as a hydraulic turbine remains an alternative for hydropower generation in meeting energy needs, especially for the provision of electricity to remote and rural settlements. The primary challenge with small hydroelectric systems is attributed to the high price of smaller size hydraulic turbines. A specific commercial pump model, with a flow rate of 12.5 m3/h, head 32 m, pressure side diameter of 50 mm, impeller out, and inlet diameters of 160 mm and 6 mm, respectively, was chosen for this research. This research aimed to investigate a pump’s flow characteristics as a turbine to help select a suitable pump to be used as a turbine for micro- or small hydropower construction. Numerical methodologies have been adopted to contribute to the thoughtful knowledge of pressure and velocity distribution in the pump turbine performance. In this study, the unsteady flow relations amongst the rotating impeller and stationary volute of the centrifugal pump made up four blades and four splitters. Intermittent simulation results of pressure and velocity flow characteristics were studied considering diverse impeller suction angles. The study was conducted by considering a wide range of rotational speeds starting from 750 rpm to 3250 rpm. From the results, it was found that PAT operation was improved when operated at low speeds compared to high-speed operation. Thus, speeds between 1500 rpm and 2000 rpm were suitable for PAT performance. This research helps to realize the unsteady flow physiognomies, which provide information for future research on PAT. This study makes useful facts available which could be helpful for the pump turbine development. Future studies should focus on cost analysis and emission generation in energy generation.
Highlights
Centrifugal pumps are commonly used for domestic and industrial applications such as water supply, energy generation, flood control, irrigation for agricultural purposes, and transportation of liquid-solid mixtures
E entire interface was designed, and the interface type was set to a fluid-fluid interface. e general grid interface (GGI) connection option was selected as the interface model for the two separate individual rotary and stator fields. e stationary blade was used for frame change
At constant flow rate and head, the turbine speed decreases when the turbine uses a higher load more than the design load; with the decrease of the burden placed on a turbine, whereas the head and flow rate remain constant, the turbine speed increases [29]. e same principle applies when hydraulic pumps are used as a turbine at a specified site with a continuous flow rate and contribute significantly to determining the turbine’s performance characteristics
Summary
Centrifugal pumps are commonly used for domestic and industrial applications such as water supply, energy generation, flood control, irrigation for agricultural purposes, and transportation of liquid-solid mixtures. Several investigational and theoretical research studies were carried out on the performance of pumps running in reverse [5]. Much attention was given to pump mode performance parameters by theoretical researchers such as [6,7,8]. Various researchers have continually conducted several research pieces to provide a PAT general performance prediction method [12,13,14]. Other researchers researched the various turbines for power generation, axial flow pumps, and energy conservation. It is conceivable to attain an high PAT efficiency level as that of pump mode operation in most cases. The turbine head usually has a higher head and flow at BEP (best efficiency point) than the pump mode at equal speed.
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