用于颗粒物采样器流量标定的元器件研究

Investigation of Components for Flow Calibration in Particulate Matter Samplers

颗粒物采样器是一种监测空气的采样和评估设备。目前,常用于采样器流量标定的元器件孔口流量计表现出线性度差、长期稳定性差的特点,且其在颗粒物采样器常用的1~120 L/min流量范围上的流量测量不确定度较大。为探索出更多可用于颗粒物采样器流量标定的元器件,通过分析不同流量计的优缺点及适用采样器流量标定的情况,以能够保证加工精度和较低加工成本的孔板及喷嘴元器件为设计对象。采用计算流体动力学CFD对不同流量范围的孔板、喷嘴元器件进行仿真,选择1~120 L/min流量范围内线性度较好的孔板及喷嘴元器件作为加工对象,根据差压流量计国标要求及仿真提供的结构参数,加工出符合要求的孔板及喷嘴元器件,并对加工出的流量元器件进行实验验证,最终设计出0.5~5 L/min、5~10 L/min、10~120 L/min三种流量范围的孔板流量计可用于颗粒物采样器的流量标定。流量范围内孔板流量计表现出械加工一致性好、流出系数线性度优于1.0%,流量长期稳定性优于1.5%以内的特点,可对后期气体采样器流量标定的元器件设计提供理论支撑,也可为采样器流量标定的元器件选型提供更多选择。

Particulate matter samplers serve as essential instruments for air monitoring,facilitating the sampling and assessment of air quality.Conventionally,orifice flowmeters utilized for flow calibration in these samplers have demonstrated inadequate linearity and long-term stability,exhibiting significant uncertainty in flow measurement within the prevalent range of 1-120 L/min.This research aims to unveil alternative components capable of enhancing the flow calibration of particulate matter samplers.An in-depth analysis was conducted,scrutinizing the merits and shortcomings of various flowmeters in relevance to their applicability in sampler flow calibration.Priority was given to the design of orifice plates and nozzle components that assure precise manufacturing and cost-efficiency.Employing Computational Fluid Dynamics(CFD),simulations were executed to evaluate the performance of these components across distinct flow ranges.Components manifesting superior linearity within the 1-120 L/min range were selected for further processing.Compliance with national standards for differential pressure flowmeters and adherence to simulation-derived structural parameters were ensured during the manufacturing of these components,followed by rigorous experimental validation.The study culminates in the design of orifice flowmeters optimized for flow ranges of 0.5-5 L/min,5-10 L/min,and 10-120 L/min,proving instrumental for the flow calibration of particulate matter samplers.Within these ranges,the orifice flowmeters exhibit commendable mechanical processing consistency,an outflow coefficient linearity surpassing 1.0%,and long-term flow stability within a 1.5%margin.These findings are instrumental,providing pivotal theoretical insights for the future design of gas sampler flow calibration components and broadening the array of choices available for sampler flow calibration components.