Local Convective Heat Transfer from Small Heaters to Impinging Submerged Axisymmetric Jets of Seven Coolants with Prandtl Number Ranging from 0.7 to 348

INTRODUCTIoNJetimpingementhasbeenextensivelyemployedintechnicalprocessestoproducerelativelyhighheat/massfluxes.Incomparisonwiththeheat/masstransferratesprovidedbyconventionaltechniqueswithfluidfiowsparalleltotheheat/masstransfersur-face,aremarkableincreaseintransfercoefficientscanbeobtainedinthisfashion.Inmostcasesairisusedastheworkingmedium.Examplesofairjetapp1icationsincludecoolingofturbinebladesandelectroniccom-ponents,annealingofmetallicandplasticsheets,dry-ingoftextilesandpaper,andtem…

Local convective heat transfer from small heaters to impinging submerged axisymmetric jets of seven coolants with Prandtl number ranging from 0.7 to 348

Using seven working fluids, a systematic experimental study was performed to investigate the local convective heat transfer from vertical heaters to impinging circular submerged jets in the range of Reynolds number between 1.17 × 10² and 3.69 × 10⁴ with the emphasis placed on the examination of Prandtl number dependence. Heat transfer coefficients at the stagnation point were collected and correlated with the plate held within and beyond the potential core. Radial distribution of the local heat transfer coefficient was measured with five test liquids. Based on the measured profiles of the local heat transfer, a correlation was developed to cover the entire range of the radial distance. Besides the present data, the correlations developed in this work were also compared with a large quantity of available data of circular air jets. General agreement was observed between the air data and the correlations.