Current Rating Improvement via CFD Modeling of Underground HVAC Cables in Natural Ventilated Troughs

Troughs provide structured and protected pathways for power cables, contributing to operational safety and long-term system reliability. However, heat dissipation within troughs plays a critical role in determining cable thermal performance. In particular, the choice between naturally ventilated and non-ventilated (sealed) troughs has a significant impact on internal airflow, convective heat transfer, and resulting cable temperatures. This study compares naturally ventilated and sealed trough configurations by analysing their thermal environments, airflow characteristics, and cable temperature distributions. Naturally ventilated troughs promote heat dissipation through buoyancy-driven convection and air exchange with the surrounding without the use of any imposed wind speed or external fans thereby, potentially increasing ampacity and thermal margins without incurring additional operational or running costs. In contrast, sealed troughs restrict air movement, suppressing convection and leading to heat accumulation around the cables, which results in elevated operating temperatures. Using analytical modelling and numerical simulations, the study evaluates temperature rise and convective heat transfer effectiveness for both trough types. The results demonstrate that limited or absent ventilation can significantly degrade cable thermal performance, whereas even modest natural ventilation provides measurable cooling benefits. These findings offer practical guidance for trough design selection, highlighting the importance of convection-driven heat dissipation alongside considerations of environmental protection, space constraints, and longterm reliability in underground power cable installations.