Burning of polymeric coatings on copper wires and glass threads: II. Critical conditions of burning

Opposed-Flow Flame Spread and Extinction in Electric Wires: The Effects of Gravity, External Radiant Heat Flux, and Wire Characteristics on Wire Flammability

“…Since the residence time of the combustion gases in the reaction zone could basically be longer under microgravity than under normal gravity due to the absence of the buoyancy-induced flow, a microgravity Although the effects of the LDPE melting, dripping, and deformation on the flame spread and its limits are hard to quantify, there were clear differences in the behaviors observed under normal gravity and microgravity since dripping and deformation are results of gravity. Their impact on the flame spread over thermoplastic materials has been examined by several previous works and the effect of fuel type, size, and orientation and the surrounding ambient conditions have also been discussed [12,13,20,[44][45][46][47]. The change of the dripping behavior associated with that of the gravity condition would have a non-negligible effect on the difference in the flame spread limits between normal gravity and microgravity because it not only carries away the enthalpy from the downstream burning region but also transports energy to the upstream unburned area.…”

“…The effects of the wire dimensions on the flammability of electric wire have been studied by several researchers [12][13][14] and identified as a quite complex problem that requires considering the impacts of many parameters, such as follows:…”

“…Electric wire combustion has the unique feature that the heat transfer through the metal conductor affects the fire performance of the insulation material during the burning event. Some researches on electric wire combustion under both normal gravity and microgravity have revealed that the role of the metal conductor in the flammability of the insulation material depends on the wire geometry [12][13][14][15] and surrounding ambient conditions such as O 2 concentration [16], airflow velocity [17][18][19][20], pressure [21], external radiative heat flux [15,22,23], and gravity [23][24][25][26]. Fujita et al [27][28][29] investigated the ignition limit and delay time of low-density polyethylene (LDPE)-insulated nichrome wires subject to short-and long-term excess electric current; they observed that the ignition limit dramatically expands in microgravity compared with normal gravity due to the absence of the buoyancy-induced flow.…”

A Numerical Study on Time-Dependent Melting and Deformation Processes of Phase Change Material (PCM) Induced by Localized Thermal Input

“…Combustion process of electric wire is, nevertheless, quite complicated since it consists of multi-phase, multi-dimensional time-dependent heat and mass transfer with chemical reactions in each phase and several fundamental processes are equally important so that it is relatively hard to simplify the system. Unlikely the conventional solid combustion, the metal rod in the wire could play an important role to determine the combustion process of the wire (Bakhman et al, 1981a(Bakhman et al, , 1981b. In this way, the thermal interaction between the metal rod and surrounded insulated matter (mainly polymeric materials) is a leading key process in understanding the fire character of the wire (Umemura et al, 2002).…”