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为有效指导市政供热有限空间机械通风现场施工,保障作业人员安全,采用CFD方法对通风过程进行数值模拟计算,研究通风过程中有限空间内部流场、温度场、氧气体积分数、二氧化碳体积分数的分布规律.结果表明:进行机械通风时,相对于供热管沟,小室内新旧空气替换较快,温度下降及气体体积分数恢复都较为迅速;供热管沟内风流场受内部结构和热升力的影响,风流主要沿管沟底部流动,管沟顶部空气速度较小、温度较高、氧气和二氧化碳体积分数恢复较慢.针对所研究的管沟,通风量为6 000、8 000、10 000、12 000、14 000 m~3·h~(-1)时,最小通风时间应分别不小于45、32、22、15、10 min.实际作业中应以管沟中段顶部空气中的氧气体积分数作为衡量通风效果的关键参数.
In order to effectively guide the mechanical ventilation in the limited space of municipal heat supply on site and ensure the safety of workers, the CFD method was used to simulate the ventilation process and study the flow field, temperature field, oxygen volume fraction, carbon dioxide volume fraction in the limited space The results show that when the mechanical ventilation is used, the replacement of old and new air in the chamber is faster than that of the heating pipe trench, and the temperature drop and gas volume fraction recovery are relatively rapid. The wind field in the heating pipe trench is affected by the internal structure and the thermal lift , The air flow mainly flows along the bottom of the trench, and the air velocity at the top of the trench is small, the temperature is relatively high, and the recovery of the volume fraction of oxygen and carbon dioxide is relatively slow. According to the studied trench, the ventilation is 6 000, 8 000, 10 000 , 12 000,14 000 m ~ 3 · h ~ (-1), the minimum ventilation time should be not less than 45,32,22,15,10 min. The actual operation should be based on the oxygen in the middle part of the ditch middle air oxygen Score as a key parameter to measure ventilation effect.