Mixed convection in a narrow rectangular cavity with bottom inlet and outlet

✍ Scribed by Gary Rosengarten; Graham L. Morrison; Masud Behnia

• Book ID: 104289318
• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 754 KB
• Volume: 22
• Category: Article
• ISSN: 0142-727X
• DOI: 10.1016/s0142-727x(00)00087-4

✦ Synopsis

A model describing the heat transfer in horizontal mantle heat exchangers used in solar water heaters has been developed by approximating a narrow horizontal annulus to an equivalent rectangular cavity. Particle tracking velocimetry (PTV) and computational ¯uid dynamics (CFD) simulations were used to determine the ¯ow ®eld. The ¯ow is in the mixed-convection regime, where buoyancy locally aects the ¯ow ®eld and heat ¯ux. The eect of the heat-transfer wall temperature distribution on the net heattransfer rate has been quanti®ed by the introduction of a strati®cation correction parameter. A mean Nusselt number, de®ned by using the dierence between the inlet temperature and mean heat-transfer wall temperature, is shown to be independent of buoyancy forces when the strati®cation correction parameter is taken into account. A correlation has been developed for the mean Nusselt number for a range of geometries and boundary conditions. This correlation predicts the net heat-transfer rate to within 10%.