Analysis of the transient state during the operation of a centrifugal pump in conjunction with an air vessel
DOI:
https://doi.org/10.17512/INSTAL.2026.08.04Keywords:
centrifugal pump, air vessel, energy storage, transient stateAbstract
The paper presents an analysis of transient operating conditions during the cooperation of a centrifugal pump with a compressed air vessel. The considered system consists of a pump delivering liquid from a suction reservoir into a closed tank containing an air cushion subjected to compression. Unlike conventional pumping systems operating close to a steady operating point, the analysed system is characterized by continuously changing hydraulic conditions caused by the increasing pressure of the compressed gas and the water column height. This means that the pump operates under dynamic conditions, and its operating point is not a steady state. This type of operation in a centrifugal pump–air tank system has not been analysed so far. This article presents a methodology for computing the parameters of such a system in a transient state. It provides equations describing the dynamics of pump startup, changes in the rotational speed of the rotating assembly, and the acceleration of the liquid column in the system. The influence of rotational inertia, mechanical losses, and variation of the static head caused by air compression is discussed. It was emphasized that the system’s characteristics change much more slowly than those of the pump during startup, which results in a periodic excess of energy transferred from the pump to the system compared to the energy lost in the system. The study discusses the applicability of similarity laws which have not been analyzed in the available literature for the case of dynamic processes and Suter characteristics for determining instantaneous pump operating parameters under transient conditions. Attention is drawn to the limitations associated with incomplete flow similarity during off--design operation. The analyzed system may form the basis for both conventional hydrophore installations and compressed-air energy storage systems employing pumps operating reversibly as turbines (PATs).
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Copyright (c) 2026 Krzysztof Karaśkiewicz (Autor)
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