外表面污垢对矿用空冷器换热性能影响的研究

发布时间：2018-10-15 10:53

【摘要】：随着矿井开采深度的增加和机械化程度的不断提高，矿井热害日益突出。矿井高温高湿环境严重危害井下工作人员的身体健康和安全，影响工作效率，已成为制约矿井安全开采的重大问题之一。因此，深入开展深井热害防治对于保障我国深部煤炭资源安全、高效的开采具有重大的理论与现实意义。矿用空冷器是矿井降温系统的末端设备，为降低矿井工作面温度提供保障，其性能好坏直接影响降温效果，所以，矿用空冷器一直被业界作为重点研究对象。 矿用空冷器在使用过程中，矿尘易沉积在其表面，高湿也会导致其表面结露而粘附更多的颗粒，从而形成污垢，，既而影响其换热效率，影响降温效果。本文主要研究矿用空冷器的外表面污垢对其换热的影响。 本文从理论上分析了矿用空冷器外表面污垢的形成及其对空冷器换热性能的影响。以某煤矿深井降温系统为原型，研究了矿用空冷器外表面污垢的厚度和污垢热导率对空冷器换热性能的影响，得到空冷器总传热系数随污垢厚度的增加而减小；污垢热导率不同时，污垢对其的影响不同，污垢对总传热系数的影响随着污垢热导率的增大而减弱；当取煤灰的热导率为1.93W/（m·K）时，空冷器的总传热系数基本不变，污垢的影响可忽略。 本文利用Gambit建立了空冷器的简化三维模型，利用FLUENT软件模拟研究了不同污垢厚度和污垢热导率对矿用空冷器换热效果的影响，通过模拟计算得到空冷器出口空气平均温度随污垢厚度的增加而升高，即换热效果减弱；污垢热导率越大，污垢对空冷器换热性能的影响越小，当取煤灰的热导率为1.93W/（m·K）时，污垢对空冷器换热性能的影响较小，可以忽略。 通过对模拟计算结果与实测数据的对比，验证了模型的相对正确性。利用验证的模型模拟计算得到了实际工况下不同污染程度时经矿井降温设备处理后的空气平均温度值，预测降温系统在实际运行的过程中，污垢的存在将直接减弱空冷器的换热，降温效果减弱，且随着污垢厚度的增加而恶化，矿井环境温度将达不到设计要求。同样的运行条件下，空冷器外表面污垢厚度每增加0.1mm，矿井环境温度升高约0.3~0.4℃。 利用所建模型，考虑污垢的影响，对运行参数风流流速和空冷器结构参数横向管间距进行了优化，得到了污垢对矿用空冷器换热的影响随风流流速的降低而减弱，即在满足降温所需风量要求的情况下，选择较低的风速可以减弱污垢的影响，和St/do=1.5（St为横向管间距，do为管外径）时污垢的影响较弱，以减弱污垢对矿用空冷器换热性能的影响。 总结了目前换热器的常用污垢防治技术，在此基础上提出了针对矿用空冷器的污垢防治对策。
[Abstract]:With the increase of mining depth and mechanization, the thermal damage of mine is becoming more and more serious. The environment of high temperature and high humidity in mine seriously endangers the health and safety of underground workers and affects the working efficiency, which has become one of the major problems restricting the safe mining of mines. Therefore, it is of great theoretical and practical significance to carry out deep well thermal hazard prevention and cure in order to ensure the safety of deep coal resources in our country and to exploit coal efficiently. Mine air cooler is the terminal equipment of mine cooling system, which provides guarantee for reducing the temperature of mine face, and its performance directly affects the cooling effect. Therefore, the mine air cooler has been regarded as the key research object by the industry all the time. In the process of application of mine air cooler, ore dust is easy to deposit on its surface, and high humidity will also lead to the surface dew and adhesion to more particles, thus forming dirt, which will affect the heat transfer efficiency and the cooling effect. In this paper, the influence of external surface fouling on heat transfer of mine air cooler is studied. In this paper, the formation of fouling on the outer surface of mine air cooler and its influence on the heat transfer performance of air cooler are analyzed theoretically. Based on a deep well cooling system in a coal mine, the influence of the fouling thickness and fouling thermal conductivity on the heat transfer performance of the air cooler is studied. The total heat transfer coefficient of the air cooler decreases with the increase of the fouling thickness. The influence of fouling on total heat transfer coefficient decreases with the increase of fouling thermal conductivity, and when the thermal conductivity of coal ash is 1.93W/ (m K), the total heat transfer coefficient of air cooler is basically unchanged. The effects of dirt are negligible. In this paper, the simplified three-dimensional model of air cooler is established by Gambit, and the effects of different fouling thickness and fouling thermal conductivity on the heat transfer efficiency of mine air cooler are simulated by FLUENT software. The results show that the average air temperature at the outlet of the air cooler increases with the increase of the fouling thickness, that is, the heat transfer efficiency weakens, the larger the fouling thermal conductivity, the less the influence of fouling on the heat transfer performance of the air cooler, when the thermal conductivity of coal ash is 1.93W/ (m K), Fouling has little effect on the heat transfer performance of air cooler and can be neglected. The relative correctness of the model is verified by comparing the simulation results with the measured data. By using the verified model, the average air temperature value after treatment by mine cooling equipment under different pollution levels under actual working conditions is obtained, and the temperature drop system is predicted in the actual operation process. The existence of dirt will directly weaken the heat transfer of air cooler and the cooling effect will be weakened. With the increase of fouling thickness, the temperature of mine environment will not meet the design requirements. Under the same operating conditions, with the increase of 0.1 mm in the thickness of fouling on the outer surface of the air cooler, the ambient temperature of the mine is increased by about 0.3 ~ 0.4 鈩

本文编号：2272322