Numerical modelling and thermal analysis of mist jet impingement in laminar regime

Abstract

Jet impingement has been traditionally one of common thermal engineering solution for cooling and heating of solid surfaces, deployed in wide range of industrial applications. Flow and thermal characteristics of single-phase jet impingement is fairly well-known owing to an extensive analytical, experimental and numerical studies. Relying on convection, as the main heat transfer mechanism contributing in jet impingement, Nusselt number increases with jet velocity and additionally by turbulent eddies influence. Therefore, thermos-fluid engineers aim for increased heat transfer rate at higher Reynolds number, while higher flow and turbulence intensity corresponds to complication of manufacturing and operational requirements. Inclusion of latent heat in thermal exchange process is also applied as one of convection enhancement techniques. This phase changing thermal phenomenon introduces new streams of investigation to the field, including boiling and partial evaporative impinging jets. Air carrying liquid micro-droplets have been remarked as mist with enhanced cooling effect, originated by partial evaporation of liquid. This paper develops and utilises a CFD model of air-water mist impinging jet to investigate associated thermal enhancement originated by mist evaporation. Species transport model is examined as accurate and resource effective approach, for the continuous-dispersed thermos-fluid problem in laminar regime. Another key element of numerical model is the coupled heat and mass transfer scheme for evaporative scheme. Operating and characteristics parameters are set according to earlier experimental study, and validated by comparison of average convective heat transfer coefficient.