An innovative method for evaluating convective heat transfer effectiveness in generator systems under complex operating conditions

With the increasing demand for high reliability and refined maintenance of marine diesel generators under diverse operating conditions, traditional experience-based condition assessment methods have become insufficient to meet the requirements for high precision and reliability. To address this issue, this study focuses on the convective heat transfer characteristics of marine diesel generators under typical operating conditions and proposes a systematic evaluation method for convective heat transfer effectiveness. First, a heat transfer efficiency evaluation framework was established, comprehensively considering key influencing parameters. Then, based on numerical simulations under multiple operating conditions, the convective heat transfer characteristics of the generator were systematically analyzed, and an empirical regression model was developed to quantitatively describe the temperature evolution of the stator coil. Finally, the model was validated using experimental data collected at different time points within the maintenance cycle, forming a closed-loop process of evaluation and verification. The results show that the convective heat transfer efficiency of the generator exhibits a significant decline over time: approximately 97.09% in the early stage, 91.54% in the middle stage, and 84.97% in the later stage, with reductions of 5.55% and 6.57% in the two intervals, respectively. This finding indicates that the continuous accumulation of fouling considerably accelerates the degradation of heat transfer performance. The proposed evaluation method demonstrates strong quantitative capability in assessing the heat transfer efficiency of the generator’s stator coil under various operating conditions. It effectively characterizes the evolution of heat transfer performance and provides a reliable theoretical foundation for condition assessment and maintenance strategy optimization of marine diesel generators.