Heat transfer enhancement method for high-voltage cable joints in tunnels

Abstract

A cable joint is regarded as a hot spot in the cable line. Especially for the case of high loads, a cable joint is prone to overheating, which can eventually cause electrical accidents such as explosions. There is still a lack of heat transfer enhancement methods to address this overheating. In this study, a forced convection method of applying cooling fan for cable joints in tunnels was proposed. Combined with the heat transfer characteristics and structural characteristics of cable joints, a forced convection thermal rating (FCTR) model was established. The effects of cooling fan positions and air velocity on cable joint heat transfer enhancement performance were determined using the FCTR model. The results show that the optimal position for a cooling fan is segment C1/C2 of a cable joint. At this position, the recommended air velocity is 4 m/s. This is because the heat transfer enhancement performance of cable joints at a higher air velocity is almost the same as that when the air velocity is 4 m/s. Based on the experimental measurements, the maximum error of the FCTR model is 2.2%. Compared with the previously reported model, the FCTR model is conducive to obtaining a more accurate conductor temperature with the accuracy improved by 4.8%. The results of this study can provide more accurate theoretical guidance for evaluating the heat transfer performance of cable joints in engineering.