Upload
paul-bryan-ocampo
View
184
Download
13
Tags:
Embed Size (px)
DESCRIPTION
lecture about convective heat transfer
Citation preview
Heat Transfer By Convection
Engr. Aki EspaldonDepartment of Chemical EngineeringRuano Drive, Faculty of EngineeringUniversity of Santo Tomas
Heat Transfer via ConvectionEnergy transfer by random molecular motion (as in conduction) plus bulk (macroscopic) motion of the fluid.
Convection: transport by random motion of molecules and by bulk motion of fluid.Advection: transport due solely to bulk fluid motion.
Forced convection: Caused by external means, (fans and blowers)
Natural (free) convection: flow induced by buoyancy forces, arising from density differences arising from temperature variations in the fluid
The above cases involve sensible heat (internal energy) of the fluid
Latent heat exchange is associated with phase changes boiling and condensation.
Dimensionless numbers in Heat TransferReynolds NumberNusselt Number
Dimensionless numbers in Heat TransferPrandtlNumber
Dimensionless numbers in Heat TransferGrashofNumber
Dimensionless numbers in Heat TransferRayleigh Number
Natural Convection
Natural Convection
Forced Convection, Heat Transfer Inside Pipes
Forced Convection, Heat Transfer Inside Pipes
Forced Convection, Heat Transfer Inside Pipes
Forced Convection, Heat Transfer Inside Pipes
Double-Pipe Heat Exchanger
Log-Mean Temperature DifferenceUtility Fluid (i.e.cooling water or steam)- AnnulusProcess fluid(i.e. Steam or product such as milk)The temperature difference between the bulk fluid and the surface of the steel pipe or insulation varies
Double Pipe Heat Exchanger
Log-Mean Temperature Difference
References Transport Phenomena, Bird, Lightfoot, StewartTransport Processes and Separation Processes Principles, Christie GeankoplisUnit Operations in Chemical Engineering, McCabe, Smith, HarriotSome slides from Prof. Morrison, Michigan Tech UniversitySome compiled slides/ notes from Engr. Andrew Tengkiat Some compiled slides/ notes from Engr. AndrewAlberto Laurito