Turbulence-induced enhancement of heat transfer performance by means of air/liquid mixing in plate heat exchangers

抄録

Enhancement of heat transfer performance results in an increase of the overall system efficiency and reflects on the process economics. This study comprises numerical analysis using Computational Fluid Dynamics (CFD) methods and reports on the results of a novel technique for enhancement of the heat exchanger performance by means of insertion of air bubbles into the flow in herringbone-type Plate heat Exchanger (PHE). Initial results revealed that air containment in water flow at a given mass flux doesn't always result in heat transfer degradation, yet there exist a certain air quality at which the overall heat transfer coefficient is seen to increase. The overall heat transfer coefficient is seen to increase by about 34~38% with insertion of air at a rate of 50 mg/kg, with an insignificant associated increase in the pressure drop. This behavior is ascribed to the increased flow velocity and hence turbulence level with the added air, the effect that overweighs the retarding effect of the declined thermal properties of the mixture. The outcome of this study is expected to pave the way for the development of novel heat transfer equipment encountered in the relevant thermal energy conversion processes.