生物质颗粒对气相温度脉动的瞬时响应

Instantaneous response of biomass particles to fluctuating gas temperatures

在生物质颗粒的湍流多相燃烧中,气相速度的湍流脉动对颗粒运动起着不容忽视的作用,而气相温度的湍流脉动是否会对生物质颗粒的瞬时温度产生影响则是有待探讨的问题。该文对置于有温度脉动的热气流中的生物质颗粒的瞬时温度变化过程进行了理论分析与计算,表明颗粒温度也会随气相发生脉动。颗粒温度脉动的幅度受到气相温度脉动强度的影响,气相温度脉动强度的增大会导致颗粒温度脉动的增强。颗粒Reynolds数的增大加强了颗粒与气体之间的对流换热,减小了颗粒的温度弛豫时间,从而加快了颗粒对气相温度的响应,增大了颗粒温度脉动的幅度。

In turbulent gas-biomass particle combustion, the turbulent fluctuations of the gas velocity affect the particle motion. However, the effects of the turbulent fluctuations of the gas temperature on the particle instantaneous temperature need to be further explored. The instantaneous temperature variations of biomass particles in a hot gas with fluctuating temperatures are analyzed numerically in this study. The results show that the particle temperatures will fluctuate with the gas temperature. The amplitudes of particle temperature fluctuations are affected by the intensity of the gas temperature fluctuations. Increases in the gas temperature fluctuations lead to increases in the particle temperature fluctuations. Increased particle Reynolds numbers enhance the heat transfer between the particles and the gas. As a result, the particle temperature relaxation time decreases, so the particle temperature responds faster to the gas temperature fluctuations and the particle temperature fluctuations increase.