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Heat transfer under multiple slot jets impinging on a permeable moving surface
Author(s) -
Polat S.,
Douglas W. J. M.
Publication year - 1990
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690360910
Subject(s) - throughflow , nusselt number , mechanics , jet (fluid) , heat transfer , thermodynamics , nozzle , flow (mathematics) , heat flux , thermal , chemistry , materials science , turbulence , physics , reynolds number
Local and average heat transfer were measured for a system of multiple jets impinging on a moving permeable surface at which there may be throughflow. Multiple jets were confined by a hood, as is required industrially for thermal efficiency. Exhaust ports located symmetrically between the jet nozzles eliminated crossflow, otherwise a strongly detrimental effect. Impingement surface motion decreases average heat transfer, by 17% at industrially relevant values of the surface motion parameter, M vs . Enhancement of impingement heat flux by throughflow is linearly additive. Expressed as Δ St , this enhancement depends only on the throughflow parameter, M us , with Δ St / M us = 0.17. For typical operating conditions, withdrawal as throughflow of only 10% of the jet flow increases mean Nusselt number by over 50%. Industrial design modeling for the potential process of combined impingement and throughflow drying of wet webs such as paper is demonstrated.