阶跃与方波示踪法测量气体的有效扩散系数

建立阶跃与方波示踪测量气体有效扩散系数的实验装置,并提出了扩散系数计算中所涉及的超越方程特征根的求解方法。采用稳态法,脉冲、方波和阶跃示踪动态法测量气体的有效扩散系数,对以扩散池为主体的各种实验方法进行评价。实验结果表明,当颗粒内的孔隙主要由大孔构成时,各种方法所得结果相近。阶跃与方波示踪法可以可靠地用来测量气体的有效扩散系数。

THE STEP AND SQUARE PULSE RESPONSE METHOD FOR MEASURING GAS EFFECTIVE DIFFUSIVITIES

An experimental system for measuring gas effective diffusivities in terms of the transient response of the tracer gas injected as step and square pulse input in a single pellet diffusion cell was established.A general computational method for searching the eigenroots of the involved transcendental equation was provided. The effective diffusivities of hydrogen gas in porous pellets prepared in the laboratory measured by different methods, namely,the steady-state method,the dynamic pulse response method including the step and square pulse response method,were compared.The results indicated that no significant difference between the steady-state and dynamic response methods was observed.The deviation of the dynamic response results from the value obtained by the steady-state method is less than 15%.It is proposed that the step and square pulse response method,as an efficient method, will be widely applied to measure gas effective diffusivities.