ESA Document - Emits - ESA

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4.5.5.3 Baseline thermal design
HMM
Assessment Study
Report: CDF-20(A)
February 2004
page 385 of 422
4.5.5.3.1 Ascent vehicle thermal control
With no direct expertise in Europe available for such vehicle, the design block proposed is based
partly on the exploitation of foreign existing heritage: Apollo LM, LOK (derived Soyuz). Space
station fluid loops technologies are applicable to a certain extent (shall work against gravity).
The thermal control philosophy adopted for such vehicle is standard and relies on the following
approach:
• simplification of the heat transfer with maximal use of thermal decoupling when
possible
• use of thermal-regulated bus to recuperate and transfer internal heat to heat sinks
• use of switch capability to modulate this transfer and balance the heat inputs from the
outputs, and thus maintain temperatures within a certain bandwidth
This is implemented using appropriate materials and technologies combining passive or active
means.
4.5.5.3.2 Thermal bus and radiator
• Docked and descent phases
Due to the staging with the SHM, a direct connection is designed with the SHM (quick
disconnect). As long as this coupling exist, the SH module thermal bus is used providing a
cooling capability when necessary.
• Landed phase
The cooling capability designed for the free flight phases is used in conjunction with the SHM
heat rejection system.
• Ascent, rendezvous and docking phases
Considering the requirement of 4 days, a complete and independent thermal control system has
to be designed. A Soyuz / LOK type thermal control is adopted:
• The secondary fluid loop is based on Polymethylsiloxane as working fluid, the
radiator located on the lateral sides of the main cylindrical body
• The primary loop is based on water as working fluid, both lines connected via a heat
exchanger
On the basis of 931W of rejected power and 330W metabolic heat, a radiator size of 8 m 2 is
needed. This is implemented in a cylindrical shape type (eight surfaces of 3.6 m x 0.71 m
length).