An Optimization of the basic design of a water jet pump for geothermal water extraction

Abstract

During the extraction of geothermal waters, their high temperature and depth of occurrence limit the use of submersible electric pumps. As an alternative, we propose the use of the basic design of water jet pumps with flow channels having conical or cylindrical surfaces, which allows their mass production at machine-building enterprises without expensive equipment. So far, the dependence of efficiency of such pumps on the design has been studied by alternately varying the geometrical dimensions, i.e., without taking into account their mutual influence. Many mutually inconsistent optimal designs have been proposed. We solved the optimization problem by means of computational fluid dynamics. When varying the geometric dimensions of the pump, a full factor experiment plan was applied. It is shown that all possible water jet pumps are geometrically similar. It is proposed to use the nozzle diameter as a natural scale. Expressions of the main geometrical dimensions of the pumps through the nozzle diameter were obtained. It is shown that the maximum efficiency of the pumps is ∼40%, and the liquid velocity at the nozzle outlet practically does not change in scaled models of the pump at fixed boundary conditions (pressures). Viscous losses grow inversely proportional to the nozzle diameter.