Calculation of the loading capacity of high voltage cables laid in close proximity to heat pipelines using iterative finite-element method

The paper presents a new iterative finite-element model for the analysis of the thermal interference between a three-phase system of high voltage cables and heat pipelines buried in close proximity. A triangular formation of 110 kV cables and a pair of polyurethane insulated steel heat pipes are considered as a characteristic real-life example in authors' country. The maximum allowable load magnitudes for cables in winter weekdays have been determined for various distances between cables and pipes. The proposed mathematical model takes into account the effects of conduction, and the heat exchange by convection and radiation on the pavement surface. In order to adequately model the convective heat transfer from the water in motion an iterative approach is elaborated based upon the properties of the Nusselt number. It was shown that the maximum allowable magnitudes of load current of cables should be decreased for app. 6% if the distance between the cables and the adjacent pipe is 3 m, which is the minimum distance usually tolerated in practice in authors' country.