TY - JOUR A1 - Solano Fernández, Juan Pedro AU - García Pinar, Alberto AU - Vicente Quiles, Pedro Ginés AU - Viedma Robles, Antonio T1 - Flow field and heat transfer investigation in tubes of heat exchangers with motionless scrapers Y1 - 2011 SN - 1359-4311 UR - http://hdl.handle.net/10317/4470 AB - Flow pattern and thermal-hydraulic characteristics in an innovative tube insert have been experimentally and numerically investigated. The insert device is a concept envisioned for reciprocating scraped surface heat exchangers. It consists of a concentric rod, that mounts an array of semicircular plugs fitted to the inner tube wall. In motionless conditions, the insert works as a turbulence promoter, enhancing heat transfer in laminar regime. Fundamental flow features in the symmetry plane of the tube have been assessed with Particle Image Velocimetry technique. A general model of the flow mechanism has been defined, identifying three regions along a geometrical pitch: recirculation bubbles, flow acceleration and transverse vortex. Results have been complemented with experimental data on pressure drop and heat transfer. The transition onset is clearly identified, and the mechanisms that promote turbulence at low Reynolds number are investigated and discussed. CFD simulations for different Reynolds numbers provide a further insight into the relation of the flow structures with wall shear stress, and their role on the local heat transfer augmentation. KW - Mecánica de Fluidos KW - Heat transfer KW - Heat exchanger KW - Scraped surface KW - Flow field LA - eng PB - Elsevier ER -