ABSTRACT
Convective heat transfer can also take place as a result of fluid motion due to the density differences upon heating or cooling and is then called natural convective heat transfer. Analysis of natural convective heat transfer. similar to forced convective heat transfer, showed that the Nusselt number is a function of Grashof (Gr) and Prandtl (Pr) numbers (k is the thermal conductivity of the fluid),
where Gr is
Gr, = x3 gf3(Tw2 - T 00 ) y
(11.301)
(11.302)
xis the characteristic distance, g is the gravitational acceleration, f3 [= (1/V)(av;aT)p] is the thermal expansion coefficient, Tw is the surface temperature of the object, T 00 is the ambient fluid temperature, and y is the kinematic viscosity of the fluid.
