An entropy efficiency model and its application to energy performance analysis of a multi-stage electric submersible pump

Abstract

The electric submersible pump (ESP) is a compact multi-stage pump that is widely used in the oil industry. In this study, using the numerical simulations with entropy efficiency (EE) model, the high hydraulic loss region within the ESP hydraulic system is captured, and the energy degradation distribution within the internal flow field is investigated and its inter-stage variability is analyzed. The input power of the ESP hydraulic system is transformed into an entropy-reducing flow, and then the EE is defined to develop a connection between localized energy degradation and the efficiency of the hydraulic system. It was found that there were significant differences among the EEs of the three stages of the ESP hydraulic system. The EE of the first stage reaches 1.29 and 1.32 times that of the second and third (final) stage respectively under overload conditions. However, the overall energy characteristics of the hydraulic system are dominated by the energy dissipation in the second and third stage. In addition, The EE for characterization of pump performance is consistent with the existing research methods in the literature, but it has the advantage of quantifying the correlation between the localized flow field structure and the efficiency of the hydraulic system. This research can provide guidance for the design optimization of ESPs and performance evaluation of related equipment which has theoretical and practical significance.