45
vapor phases from a region of differing temperature less the latent
energy required for evaporation of water. Examining this for the jth
node in the discretized domain, the above equation can be expressed in
terms of heat flux transferred (q) into node j from the surrounding
nodes as.
dx-dydwj)qsj = dx-dy (qcj+l,n + qcj-l,n + qLj+l,n
+ qLj-l,n + qvj+l,n + qvj-l,n)
(dx-dy-dwj)qej,n
(2-55)
The subscripts
s :
c :
e
L :
v
j :
j+l
j-1
n
in the above representation denote
change in sensible heat
heat conduction
latent heat
heat transfer due to diffusion of water (liquid)
heat transfer due to diffusion of water vapor
the current node
the node immediately following node j, and
the node immediately preceding node j.
the current time step
and
dx-dy :
dx-dyddwj :
dwj :
The change in
to n+1 is
cross-section area normal to z axis
volume of the node j
height of the cell for node j
sensible heat per unit volume of node j from time step n
Tj,rn+ Tj,
qsj = Cs dt
(2-56)
The heat flux conducted from nodes j+1 and j-1 to node j at a given
time step, n, is described by Fourier's law of heat conduction and is
expressed as follows