关键词: 撞击流, 射流, 旋流, 射流孔板, 强化传热

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