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In this work, a detailed study of the thermal-hydraulic characteristics of oscillatory flow reactors is carried out. These devices consist of a tubular equipment with a net flow in which an insert is introduced to promote mixing and, additionally, an oscillatory flow is superimposed. The inserts which have been studied are the single orifice baffles and the three orifice baffles. The interaction between the inserts and the oscillatory flow promotes the heat transfer and the radial mixing, allowing for their operation with low net flows (which can lead to a laminar flow) and, at the same time, obtaining high heat transfer coefficients and mixing intensities. Chemical reactions with a high residence time are the main application of these devices. These kind of reactions require working with low net flows to obtain a reasonable size of the equipment. The methodology used throughout this Thesis has been mainly experimental. One of the greatest complexities of these devices is the oscillatory behaviour of the flow, which required the development of a specific methodology for this application, both for the flow visualization and for the power dissipation measurements. The flow patterns have been studied using two complementary techniques: hydrogen bubbles visualization and Particle Image Velocimetry. The tests have allowed us to observe the flow behaviour under several operating conditions: net flow, oscillatory flow or both superimposed. The power consumption associated with the net flow operation has been characterized by the Fanning friction factor, measured for a wide range of net Reynolds numbers, detecting the laminar, transitional and turbulent flow regimes. Regarding the power consumption associated with the oscillatory flow, a wide range of oscillatory Reynolds numbers and oscillation amplitudes have been tested, providing dimensionless experimental results. To this aim, the oscillatory Fanning friction factor and the Power number have been defined. Heat transfer has been studied for a wide range of net Reynolds numbers, oscillatory Reynolds numbers and Prandtl numbers; Nusselt number correlations as a function of these dimensionless numbers are provided. Other aspects relevant to heat transfer are studied, such as flow stratification or the local Nusselt number. Finally, a numerical model has been developed in order to study the pressure drop under laminar flow conditions and net or oscillatory flow. This model has been validated using experimental results, and has allowed us to study other aspects such as spatial and temporal periodicity. These results have allowed us to broaden our knowledge about certain aspects, which are not properly explained in the open literature, of oscillatory flow reactors. This knowledge will make possible a more precise design of these devices in the near future.

Análisis experimental de los mecanismos de mejora termohidráulica en reactores de flujo oscilatorio