Abstract: Aiming at the problem of insufficient heat transfer in chemical processes characterized by strong exothermicity, low flow velocity, and long residence time, a novel impinging stream composite orifice jet reactor is proposed. This structural innovation integrates impinging stream technology with orifice jet technology, in which the newly developed orifice plate is the key component to break through the heat transfer bottleneck of traditional reactors. Numerical simulation method is adopted to study the heat transfer performance and enhancement mechanism of this novel reactor, with a focus on analyzing the effects of the ratio of the spacing between inflow pipes to the inner diameter of the inflow pipe (c/d1), number of novel orifice plates, and jet orifice tangential angle (βo) of novel orifice plates on the reactor's heat transfer process. The results show that the ratio of the spacing between inflow pipes to the inner diameter of the inflow pipe has a significant impact on heat transfer. The average Nusselt number (Nu) on the tube wall first decreases and then increases as the spacing to diameter ratio increases, reaching the maximum when c/d1=0.5 and the minimum when c/d1=2, a decrease of 22.99% compared with c/d1=0.5, while the Nu at c/d1=5 is 4.8% higher than that at c/d1=2. More importantly, orifice plates with a tangential angle βo ranging from 100° to 130° can all improve the heat transfer effect of the reactor, and their comprehensive heat transfer performance is superior to that of traditional reactors, with higher heat transfer performance at lower flow velocities. Among them, the orifice plate with βo=100° achieves the best effect, with the Nu increased by 231.56% compared with the traditional reactor, and the relative deviation of the local average heat transfer coefficient is as high as about 300%. Furthermore, the superposition of multi-stage orifice plates can further extend the range of heat transfer enhancement, which is a unique advantage brought by the innovation of orifice plates. Focusing on the novel orifice plate, this study not only verifies the feasibility of the structural innovation of the reactor, but also provides important reference for the development of high-efficiency heat transfer equipment and the optimization of heat transfer processes in the chemical industry.

Key words: impinging stream, jet flow, swirling flow, jet orifice plate, enhanced heat transfer

摘要： 针对强放热、低流速、高停留时间的化工过程强化传热，本工作提出一种撞击流复合孔板射流新型管式反应器，通过数值模拟探究其传热性能及强化机理。结果表明，入流管间距与入流管内径之比c/d1对管壁平均努塞尔数Nu调控显著，随c/d1增大传热性能先减弱后增强，c/d1=0.5时Nu最大，c/d1=2时最小(较c/d1=0.5降低22.99%)，c/d1=5时Nu较c/d1=2提升4.8%。孔板射流孔切向角为βo=100°~130°的孔板均能提升反应器传热效果，综合传热性能优于传统反应器，且流速越低传热性能越高，其中βo=100°的孔板效果最佳，Nu较传统反应器提升231.56%，局部平均传热系数相对偏差约300%，且多段孔板叠加可延长传热强化范围。机理分析显示，孔板可促使流体形成周期性涡结构、诱导旋流并增强近壁区速度梯度与温度梯度，实现热边界层减薄。本工作旨在为反应过程换热强化提供理论基础，为工程应用提供指导作用。

关键词: 撞击流, 射流, 旋流, 射流孔板, 强化传热