Energy balance analysis for a canned motor pump used for heat supply system

Abstract

A canned motor pump is widely used for transporting the liquids without leakage. In this work, the pump is applied for heat supply system. For this application, between the rotor and stator for cooling the canned motor there is a circulating flow, which will flow back in the pump passage with higher temperature, and bring the mixing of the liquid having different temperature between the main stream and the circulating flow. The steady state internal flow has been investigated for the pump, and the pump hydraulic performance has been compared with the experimental data. With the consideration of both mechanical energy and internal energy as the effective energy increment of the working fluid, an efficiency assessment is proposed for a canned motor pump. The proposed efficiency shows the same tendency as hydraulic efficiency, and is more understandable compared with that of the conventional method. The present results indicate that the proposed method of evaluating the efficiency of the canned motor pump can reasonably depict the energy balance inside the whole canned motor pump. Further, the introduction of circulating flow is helpful to predict the internal flow and heat transfer for the canned motor pump in numerical simulation with better accuracy. The present study is helpful for both development and application of high performance canned motor pump for various industries.