ESA Document - Emits - ESA

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cryocooler heat lift [W]
cryocooler heat lift [W]
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
Hydrogen (22.9K, 0.2MPa, sink 300K)
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
tank diameter [m]
1 tank 2 tanks 3 tanks 4 tanks 6 tanks
8 tanks 11 tanks 16 tanks BO=0
Hydrogen (22.9K, 0.2MPa, sink 250K)
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
tank diameter [m]
1 tank 2 tanks 3 tanks 4 tanks 6 tanks
8 tanks 11 tanks 16 tanks BO=0
Figure 4-43: Cryocooler heat lift for the hydrogen storage
cryocooler heat lift [W]
cryocooler heat lift [W]
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
Hydrogen (31.4K, 1MPa, sink 300K)
HMM
Assessment Study
Report: CDF-20(A)
February 2004
page 291 of 422
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
tank diameter [m]
1 tank 2 tanks 3 tanks 4 tanks 6 tanks
8 tanks 11 tanks 16 tanks BO=0
Hydrogen (31.4K, 1MPa, sink 250K)
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
tank diameter [m]
1 tank 2 tanks 3 tanks 4 tanks 6 tanks
8 tanks 11 tanks 16 tanks BO=0
In the figure top right and bottom right, the pressure is increased to 1 MPa to reach a boiling
temperature of 31.4K, while in figure left and right bottom the sink temperature is lowered to
250K. Since the density of the fluid decreases with an increase of temperature, more tanks (and
more mass) are required to accommodate the same volume of liquid. Significant advantage is
found however on the efficiency of the cooler that doubles (less input power) and on the BO rate
(lower heat of evaporation). The number of MLI layers is traded off in the left figure in Figure
4-44, and shows that doubling this number decrease the required heat lift of a factor 2. In the
same way, in the right figure in Figure 4-44, is shown that decreasing the sink temperature from
300K to 250K (still in the operative range for the electronics) allows the heat lift to drop by a
factor of 2.