EXPERIMENTAL APPROACH TO ASSESS EVAPORATIVE COOLING UNDER FORCED AIR FLOW

• Autor(a) principal: Rodrigues,L. G. G.
• Data de Publicação: 2017
• Outros Autores: Parisotto,E. I. B., Carciofi,B. A. M., Laurindo,J. B.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Brazilian Journal of Chemical Engineering
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322017000100171
• topic: Air blast chilling; Cold chamber; Convection; Heat and mass transfer; Effective heat transfer coefficient

Abstract Air blast is one of the most employed industrial chilling methods. It can be enhanced, i.e., increasing heat transfer and reducing cooling time, by superficial evaporative phenomena. This work reports a methodology, including experimental setup and mathematical modelling, to quantify the air chilling enhancement by wetting the surface of the object to be chilled. A spherical metal model was covered by a cotton tissue (wet or dry) and placed into a cold chamber. The effective heat transfer coefficient was determined at different temperature, air velocity, and relative humidity from time-temperature profiles into the sphere. Under the same air conditions, the effective coefficient between sphere and air was increased three-fold by moistening the cotton tissue on the sphere surface. Furthermore, comparing a dry and wet surface showed that evaporative cooling resulted in much shorter chilling times. The proposed approach was able to assess evaporative heat transfer by measuring only the time-temperature profile, and is suitable for industrial applications.