METODOLOGIA APRIMORADA DE DIMENSIONAMENTO ECONÔMICO E HIDROENERGÉTICO EM RECALQUE

Abstract

This work presents a methodology for the economic sizing of water pumping systems powered by electricity from the Brazilian utility grid. The methodology was implemented in the development, of computer application, named Supply, using Visual Basic language. Employing computational resources to determine solutions saves planning time, prevents quantification errors, enables simulation of various implementation and operational scenarios, and, most importantly, enhances the system modeling. The hydraulic, electrical, and economic modeling of the system was refined following a comprehensive literature review on the subject. Sizing is performed through cost analysis using the trial-and-error method, guided by the Bresse equation to determine which pipeline diameters should be tested. Continuous head loss can be calculated using either the Darcy-Weissbach equation or the Hazen-Williams equation. Localized head loss can be determined using the equivalent length method, the direct method, estimationbased on continuous head loss or may be neglected. The economic diameter for the pipeline is the one that minimizes the total annual cost, which comprises both implementation and operating expenses, with particular emphasis on the impact of electricity costs. To maximaze economic efficiency alternative sizing techniques such as the use of frequency inverters, capacitor banks, and on-grid photovoltaic systems have been proposed. After its development, the Supply software was used to test several hypotheses raised regarding the optimization of the operational regime of water pumping systems and to assess the economic feasibility of the proposed alternative techniques. The hypotheses examined included the feasibility of using a frequency inverter to select the optimal operating point, the use of a capacitor bank and an on-grid photovoltaic system to reduce operating costs, the connection of medium-voltage consumers to the low-voltage grid to lower expenses, and increasing flow rates to reduce operating time and enhance the economic efficiency of continuously operating systems. The Supply application contributed to the validation of these hypotheses, demonstrating strong operational performance. It was concluded that this tool can significantly enhance the economic efficiency of both new projects and the renovation of existing systems, assisting engineers, technicians, and academics in determining optimal solutions and promoting the rational use of resources. Keywords: Water pumping, Design, Economic efficiency, Solar energy, Power factor, Frequency inverter.