MODELING THE HEAT TRANSFER IN CABLE PENETRATIONS AT THE DETERMINATION OF FIRE RESISTANCE LIMITS

A mathematical model of heat transfer in cable penetration at the thermal fire influence is proposed. This model allows to study the processes of heat distribution between the elements of cable products and cable penetration construction. A software package based on the finite element method was used for numerical implementation of the proposed mathematical model. To study the influence of cable penetration construction on the cable heating processes there are considered three most common types of penetrations. The dependences of the temperature both of the cable structural elements and the cable penetration on time are obtained. It has been established that if the construction includes air space or a material, that contributes to intensive heat exchange, its fire resistance limit increases. The most dangerous type of cable penetration with filling the entire internal space with fire-fighting foam based on polyurethane foam has been determined in terms of heating the cable and reducing the fire resistance limit.