Abstract: A wet process of PM_2.5 removal from industrial waste gases was proposed, with cooling and condensation in the axial channel of a spiral plate exchanger. The characteristics of thermo-phoresis and diffusion-phoresis of PM_2.5 with vapor component in the boundary layer of heat and mass transfer were pointed out. A pseudo-homogeneous model was built based on the mechanism on dust removal by condensate film absorption. Subsequently, the attenuation function of PM_2.5 concentration was deduced. The dust removal efficiency equation, with the condensate flux n_w and the waste gas inlet velocity u₀ as the variables, was obtained. Parameters in the model were derived by means of analogies of momentum, heat and mass transfer, and verified with the experimental data of cooling and condensation under constant wall temperatures. It is shown that the key factor is the vapor diffusion volume flux (or called PM_2.5 diffusion-phoresis velocity) V_w with the magnitude of 20—40 mm·s^-1.

Key words: spiral plate exchanger, axial-cross flow, cooling and condensation, wet dust removal, pseudo-homogeneous model

摘要： 提出了螺旋板换热器轴向错流通道冷却冷凝湿法除尘的方法，指出了PM_2.5在尾气对流传热传质边界层内热泳和伴随水蒸气冷凝的扩散泳运动特征和冷凝液膜吸收除尘机理并建立了拟均相模型，获得了PM_2.5浓度衰减函数和以冷凝通量n_w为参数的捕尘效率模型。通过“三传”类比获得了从尾气流速求取模型参数的方法，并通过恒壁温条件下冷却冷凝实验数据验证了模型参数计算方法的正确性，结果表明水蒸气组分扩散体积通量即PM_2.5扩散泳速度V_w是控制性参数，其值在20～40 mm·s^-1范围。

关键词: 螺旋板换热器, 轴向错流, 冷却冷凝, 湿法除尘, 拟均相模型