Applying Criteria Equations in Studying the Energy Efficiency of Pump Systems

This paper presents a method for evaluating the energy efficiency of pump systems used to transport fluids .It is mainly scientifically applied and engineering-applied in nature and aims to propose a new approach (method) to researchers in their study of the energy efficiency of such systems. By applying the well-known scientific method of Dimensional Analysis (Buckingham pi-theorem), dimensionless complexes (pi-criterions and their relevant equations, which are original (innovative) and are offered for the first time in the scientific literature), used in accomplishing an energy assessment and analysis of such systems, are obtained. The criterion Pi(1) = e(v)/rho gD represents specific energy consumption in kWh/m(3) for a given pipe system with an exemplary diameter D. The criterion Pi(2) = Q/[n(H-p - H-st)D-2] represents a generalized parameter which is characterized by the selected method of flow rate (Q) regulation for a pump system with given static head H-st-by changing the speed of rotation (VFD, Variable Frequency Drive), by throttling, leading to an increase of the system hydraulic losses h(v) = (HpHst) or by diverting a part of the flow, known as "by-pass", where the pump operates with the required system head H-p, but ensures higher flow rates, i.e., Q(p) > Q(s). The flow rate criterion Pi(3) = Q/(nu D) characterizes the flow rate for a pipe system with an exemplary diameter D, used to transport a liquid with known viscosity nu. An example for applying these dimensionless complexes in accomplishing a quantitative evaluation of the energy efficiency of a given pump system is presented. A method for determining the main parameters forming these criterions, used to describe the different methods of flow rate regulation, has been developed. To demonstrate the application of this method, newly proposed by the authors, including obtaining the relevant criteria equations of the type Pi(1) = f(Pi(2), Pi(3)), a certain pump system was used. This original approach for studying pump systems used to transport fluids can be used both to accomplish an energy analysis of such systems as well as to solve for optimization or other engineering problems.