应用于恶臭气体稀释嗅辨新型文丘里管设计及优化

Design and Optimization of a New Venturi for the Dilution and Sniffing of Malodorous Gases

摘要: 本文设计了一种新型的文丘里管，以套管结构代替渐扩管段，增加气体的动能传递效率，目的是解决异味评价中测试仪器气体稀释范围、稀释精度、混合效率等问题。CFD实验对径向流量及截面浓度分布模拟，结果表明进气口压力条件与出口体积流量具有良好的线性关系，决定系数R²为0.992，当相对压力为150 kPa时，能很好满足出口体积流量20 L/min的要求。以正丁醇(n-butanol)为模拟过程的标准气体，测试点位浓度均值为0.2673 ppm，不均匀度S_d为0.127，当S_d < 0.20时，表明通过出口截面正丁醇浓度分布均匀。根据EN-13725进行实验验证，在满足t分布的95%置信区间即δ_w,d取值为(−0.0541, 0.0431)时，计算精度A_d为0.108，满足A_d取值不超过0.20的要求，测试精度与设计值吻合。

Abstract: In this paper, a new venturi with a casing structure rather than a tapering section is designed to increase the kinetic energy transfer efficiency of the gas, with the goal of solving the problems of gas dilution range, dilution accuracy, and mixing efficiency of the test instrument in odor evaluation. CFD simulations of the radial flow rate and cross-sectional concentration distribu-tion show that the inlet pressure condition has a good linear relationship with the outlet volume flow rate, and the decision coefficient R² is 0.992, and when the relative pressure is 150 kPa, it can well meet the requirement of 20L/min. The mean concentration at the test point is 0.2673 ppm with n-butanol as the standard gas for the simulated process, and the inhomogeneity S_d is 0.127. When S_d = 0.20, it means that the n-butanol concentration is distributed uniformly through the out-flow portion. When the 95% confidence interval of the t-distribution is satisfied, i.e. δ_w,d is taken as (−0.0541, 0.0431), the estimated accuracy A_d is 0.108, which meets the condition of A_d not exceeding 0.20, and the test accuracy equals the design value, according to EN-13725.