IEA Solar Heating and Cooling Programm - NachhaltigWirtschaften.at

IEA SHC Task 38 Solar Air Conditioning and Refrigeration Subtask C2-A, November 9, 2009
A basic element in the angular and width direction of the desiccant wheel is considered and
can be presented as follows:
dθ
R
dz
Air
Figure 19: Basic element of the desiccant wheel
Fundamental equations of heat and mass transfer for the basic element
Mass conservation equation
∂W
⎛ ∂wa
∂wa
⎞
M
d
+ ma
⎜ + u ⎟ = 0
(27)
∂t
⎝ ∂t
∂z
⎠
Mass transfer equation
M
d
∂W
∂t
= h
m
S
( w − w )
a
eq
Heat conservation equation
∂H
⎛ ∂ha
∂ha
⎞
M
d
+ ma
⎜ + u ⎟ = 0
(29)
∂t
⎝ ∂t
∂z
⎠
Heat transfer equation
M
d
∂H
∂t
= h
m
S
( w − w )( h + c T ) + h S( T − T )
a
eq
fg
pv
a
t
a
d
(28)
(30)
Variable change
The time t is related to the angular position θ with the following equation
t
τ
ro
=
θ
π
so
τ ro
t = θ ,
π
Where τ ro is the rotation period of the process or regeneration and N is the angular speed of
the wheel.
page 47