IEA Solar Heating and Cooling Programm - NachhaltigWirtschaften.at

IEA SHC Task 38 Solar Air Conditioning and Refrigeration Subtask C2-A, November 9, 2009
( cm i,
j
Td
i,
j
− cm i−1,
j
Td
i−1,
j
) + ( ca i,
j
Ta i,
j
− ca i−1,
j
Ta i−1,
j
) + ma
' h
fg
( wa i,
j
− wa i−1,
j
)
+ ( c * T − c * T ) + m * h ( w − w )
a
= −M
i,
j
d
' h
a i,
j
fg
∆λ
k
a
i,
j−1
Heat transfer equation
( c T − c T )
m i,
j
= −M
d i,
j
d
' h
fg
a i,
j−1
( exp( −kW
) − exp( −kW
))
m i−1,
j
di−1,
j
i,
j
− h'
w
a i,
j
a
fg
− h *
i−1,
j
i,
j
T
a i,
j
a i,
j
a i,
j−1
+ h S'
T
c
d i,
j
(39)
∆λ (40)
( exp( −kWi,
j
) − exp( −kWi
−1,
j
)) − h'
weq i,
j
k
With the following coefficients [19]
M
d
π M
d
' =
τ
ro
S = S ∆θ
∆z
∆z
m
' h '= hm
S'
h
fg
π m
∆z
a
a
' =
m = m u ∆θ
τ
* a a
ro
= M
d
( c
pd
c
pv
Wi
j
)
c
a i, j
= ma
'( c
pa
+ c
pv
wa
i,
j
)
= m ( c c w )
h = h S'
c ( w − w ) h '
c
m i, j
' +
,
c
a
*
i, j a
*
pa
+
pv a i,
j
*
i , j m pv a i,
j eq i,
j
+
c
S
For the details of the boundary conditions of the model please check the French
version of [1].
Model performance
The above presented model of the desiccant was implemented in SPARK. The figure below
shows the evolution of the air and the desiccant properties inside the wheel for an inlet
temperature of 30°C, inlet humidity ratio of 12 g/k g, regeneration temperature of 60°C and
regeneration humidity ratio of 12 g/kg. The figures show the temperature and the humidity
ratio distribution as a function of the angular position (0 to 180°) and as function of the width
(0 to 0.2m) of the wheel for the process sector.
page 51