Heat transfer characteristic research based on thermal network method in submersible motor

A novel thermal network method is introduced to investigate the heat transfer characteristic of submersible motor in the paper. According to the special structure of motor and the related theories, the thermal network model is established. The equivalent thermal resistance in the model is calculated with improved empirical formula. And to improve the accuracy of the calculation, considering the influence of the manufacturing process on the temperature rise of the motor, the thermal-contact resistance is introduced for the equivalent thermal resistance of different materials. The influence of oil flow in the inside and outside of the motor to the motor temperature rise is also fully considered, so Gauss-Seidel method is used to realize temperature field and fluid field coupling. Each node temperature is solved by energy balance equation, and the second law of thermodynamics is introduced to analyze motor heat characteristic, so that it can improve motor performance by analyzing the entropy generation and the exergy destruction rate of motor. Finally, compared with the prototype temperature test, it shows that the calculated results are close to the test data. This method provides a certain basis for the motor heat transfer characteristic analysis.