Bio-heat response of skin tissue based on three-phase-lag model

In this article, the thermal response of skin tissue is investigated based on three-phase-lag (TPL) model of heat conduction. The governing equation of bio-heat conduction is established by introducing both the TPL model of heat conduction and a modified energy conservation equation. The analytical solution is obtained by adopting the method of separation of variables and a parametric study on temperature responses in TPL model is carried out. It is shown that the TPL model can predict both the diffusion and wave characteristics of bio-heat conduction. Increasing the phase-lag of thermal displacement gradient would result in the rise of thermal propagation speed and decrease the temperature in affected zone. The perfusion rate of arterial blood has no obvious effect on thermal propagation velocity and thermal propagation lagging. Increasing of the rate of blood perfusion contributes to decreasing the temperature of steady state.

Thermal Runaway Characteristics of a Large Format Lithium-Ion Battery Module

The overheat abuse experiment of a 12S1P 37 Ah prismatic Lithium-ion battery module in a nominal energy of 1.65 kWh is conducted in this work. The cell behaviors and characterization in the process of thermal runaway propagation is investigated, including the gas eruption, the fire ejection, the flame combustion, the audio features, and the heat transfer, respectively. In the experiment, the central cell is heated on both sides until the pole temperature moves beyond 300 °C, the thermal runaway undergoes about 43 min and propagates from the central to both sides in the module, and all 12 cells burn. Results show that the first three runaway cells spout gas at first, and, then, emit sound with close amplitudes, frequencies, and energies, about 200 seconds earlier than the fire ejection. Then, the characteristic of the internal short circuit is the temperature rate zone of 1.0 K/s with time greater than 20 seconds. Moreover, the proposed thermal propagation coefficient is used to assess the thermal propagation capabilities of the runaway cells on their adjacent cells, and this explains the runaway sequence. It is anticipated that the experimental results can provide the deep understanding, thermal runaway warning, and evaluation method for the module safety design.