To address the local overheating in the busbar contact region of medium-voltage switchgear caused by high heat flux density, a passive heat dissipation scheme using an embedded heat-pipe-assisted conductor is proposed. An electromagnetic-thermal-fluid-phase-change multiphysics coupled model is established to clarify the influence of heat pipe structural parameters and operating conditions on the temperature rise characteristics of the busbar. The simulation employs a copper–water heat pipe with a 100-mesh sintered copper wire mesh wick and a working fluid filling ratio of 100%. Under conditions of a load current of 500 A, a contact resistance of 10 μΩ, and a busbar length of 300 mm, embedding a heat pipe with a diameter of 5 mm reduces the hotspot temperature of the busbar by 1.9 K; when the busbar length increases to 600 mm, the temperature reduction increases to 2.4 K. When the load current increases to 1300 A, the temperature suppression effect of the heat pipe is significantly enhanced, and the hotspot temperature decreases by 13 K; when the contact resistance increases to 40 μΩ, a temperature reduction of 9.8 K is still achieved. The results indicate that the phase-change heat transfer intensity increases adaptively with increasing thermal load, and the system operating point remains far from the capillary limit, with a safety margin of 2.86. Transient characteristics show that the introduction of the heat pipe extends the temperature rise delay time of the busbar under load step by 385 s. Based on the Arrhenius equation, the proposed scheme can extend the expected lifetime of the busbar under high-temperature conditions by approximately 77%. The embedded heat pipe establishes an axial latent heat transport channel, effectively overcoming the axial heat conduction bottleneck in long conductors and significantly improving the thermal reliability and long-term operational stability of the busbar without altering the external profile.
Zheng et al. (Wed,) studied this question.