Experiment And Simulation Study Of Heat Transfer Process Of An Oscillatory Flow Reactor With Conic Ring Baffles

The oscillatory flow reactor(OFR) is a promising process intensification equipment. Even at low flow rates it can reach approximate RTD as plug flow. The magnitude order of radial velocity of fluid equals to its axial velocity, which makes the system good mixing and results in efficient heat and mass transfer performance. In addition, the control of OFR is simple and precise. Appropriate degree of mixing will be achieved by adjusting amplitude and frequency. There are broad application prospects in chemical reactions, suspension polymerization, industrial crystallization and other industry processes.Conic ring baffles were designed to solve the accumulation of solid particles on ring-type baffles. It has great application potential in liquid-solid systems. The flow field of OFR has been reported in the literatures currently, which were based on isothermal processes. This paper took account in temperature changes, and investigated heat transfer performance of OFR with conic ring baffles.The tube used in this thesis was a50mm inner-diameter stainless steel pipe. The baffle spacing was75mm. Nusselt number was used to show the heat transfer performance of OFR with conic ring baffles. The relationship between Nuo, Pr, Reo and Ren was as follows: Nuo=0.0015Pr0.4Ren1.11+0.37Pr0.4Reo0.68(700<Reo<14000) It was seen that a13-fold improvement of Nuo could be obtained under certain conditions as compared to smooth tube.The geometric model used in simulation had10cells. Structured and unstructured meshing method was adopted to discretize the computational domain with a total grid number of981532. The RNG k-ε two-equation model was introduced to simulate the turbulent flow. In the discretization of the control equations, the transient term employed the second order backward Euler scheme, the convective term used the high resolution scheme, and diffusion term adopted the central difference scheme.The visualization of flow field and temperature field showed that a pair of stretching vortex were formed at the upstream of OFR cell, which was the main reason for the radial mixing. A pair of compressed vortex were formed at the downstream with a smaller influence to the system. The interaction between the vortex and the mainstream caused enhanced heat transfer mainly.There was a wide gap of Nuo between experiments and simulation which employed default model parameters. This article has revised simulating parameters and found that amendment of a single parameter(Prt, Cμ C1ε or C2ε) couldn’t match the experimental results. Therefore, multi-parameter corrections were applied. It was found that at Reo=3500, when C1ε was set to 0.71and C2ε was set to2.52, the computational result matches the experiment results.