ESA Document - Emits - ESA

s
sun flux (W/m2)
450
400
350
300
250
200
150
100
50
0
radiator area [m2]
Sun flux on the SHM (Ls 180, lat. 0)
0 4 8 12
time (hrs)
16 20 24
top sunrise direction sunrise dir. + 90 deg.
sunrise dir. + 180 deg. sunrise dir. + 270 deg.
Figure 4-33: Local sun flux on SHM (equinox, lat. 0)
WP radiator (eff. 0.8), mean fluid at -5C, P=2.4kW
-120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0
rad. sink temp. [K]
Figure 4-32: Bottom radiator facing ground sink
Radiator area [m2]
30
28
26
24
22
20
18
16
14
12
10
cylind WP radiato r, me an fluid tmp -5C , v ie w fa ct. t o gro und 0.5
HMM
Assessment Study
Report: CDF-20(A)
February 2004
page 285 of 422
-120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10 20
rad. sink [K]
0 W/m2 50 100 150 200
Figure 4-34: Sensitivity rad. versus sink and sun flux (equinox,
lat. 0)
The proposed configuration is therefore a conical compartment upon which a body-mounted
radiator is designed. Impingement from braking plumes is minimised with proper orientation and
location of the thrusters. The duration of thrust is assumed short so cumulated heat and
contamination of the radiator should be low. However if not sufficient, protective foil (titanium)
can be installed locally. The total radiative surface allowed with this configuration (sized for a
max sink of –10C) is 17.7 m 2 (total surface of the compartment zone) + 4.5 m 2 (upper cylinder
3.6 x 0.39 m length).
Flexibility exists in the fluid loop system and shall be included in the heat management to
optimise the thermal design and its related budget. For example, heat rejection around noon can
be delayed a few hours (permitting a certain temperature increase of the working fluid) until the
sink reaches an admissible level, this to avoid an excessive radiator sizing.
70
65
60
55
50
45
40
35
30
25
20
15
10