松散煤体导热系数的温度及粒度效应

Effect of temperature and particle size of thermal conductivity in loose coal

松散煤体导热系数受诸多因素影响,但对于同一煤体,其导热系数主要与温度、粒度有关。通过建立松散煤体的热传导模型,对导热系数采用二分法逐步逼近,数值模拟不同环境温度、不同粒度煤体传热过程的温度变化规律,并与实测结果对比分析,进而确定与实测规律吻合最好时的煤的导热系数。研究结果表明:采用二分法逐步逼近取得煤样导热系数的模拟结果可无限接近实测结果,进而确定煤的导热系数是切实可行的。在不同的环境温度下,煤的传热过程温度变化规律差异较大,同一粒度煤样,其导热系数值随环境温度升高而线性增大。同一环境温度下,粒度较小时对导热系数影响较大,而粒度较大时对导热系数影响较小。该方法也可用于其它同类型材料的导热系数测定,具有一定的实用价值。

The thermal conductivity of loose coal can be affected by different factors,but for a given coal,the thermal conductivity is mainly related with temperature and particle size. A heat conduction model of loose coal was established to numerically simulate the temperature change law of coal during heat transfer process with different environment temperature and particle size,in which the thermal conductivity was obtained with successive approximation method on the basis of the dichotomy. Compared with the test results,the thermal conductivity was determined,which had the best agreement with experimental law of heat transfer process. The results showed that it is feasible to obtain thermal conductivity of loose coal with dichotomy,which can be used to simulate the heat transfer law and can be infinitely close to the measured results. Under different environment temperature,the change laws of coal temperature have bigger difference during heat transfer process,with the same particle size of coal sample,the thermal conductivity linearly increases with the rising of environment temperature. Under same environment temperature,smaller particle size of coal sample has greater influence on the thermal conductivity,but larger particle size of coal sample has weaker effect on the thermal conductivity. This method can also be used in the measurement of heat conductivity coefficient for other similar material,which has a certain practical value.