Method of evaluation of efficiency improvement potential for water supply systems with focus on variable speed centrifugal pumps

Abstract. The goal of this research is the derivation of the method for evaluation of efficiency improvement potential for public water supply systems with a focus on centrifugal network pumps. The efficiency of proportional pressure control usage has been analyzed for variable speed pumps. It has been done if proportional pressure control is used in comparison with constant pressure control mode. For this reason, energy calculation analyses have been realized for variable speed centrifugal pumps, and the theoretical tool of estimation of the efficiency improvement potential for public water supply systems has been derived. The conclusions are as follows: (1) it has been found that 1110 MWh of annually consumed electrical energy can be saved up, if the control mode of variable speed network pumps will be changed from constant pressure to proportional pressure control mode with the deviation of 20% from head value of duty point at zero flow; (2) about 13 MWh of annually consumed electrical energy can be saved up, if the proportional pressure control mode with the deviation of 15% will be changed to the deviation of 20%; (3) totally about 1123 MWh or 1.12 GWh (14% of the annually consumed electrical energy by variable speed network pumps) can be saved up in small public water supply systems in Latvia.