ESA Document - Emits - ESA

s
HMM
Assessment Study
Report: CDF-20(A)
February 2004
page 172 of 422
• both selections depend on the required performance and the allocated budget from the
system (mass, power, environment)
Table 3-23 shows the characteristics of the fluid loop selection:
Type Advantage Disadvantage
Single phase fluid loop Predictable, testable
No limitation of heat removal (depends on the
pump capability)
Heritage: all vehicles and stations (Soyuz,
Apollo, MIR, ISS)
Two phase mechanical
pump loops
Capillary Pump Loop
(CPL)
Lower fluid flow rate for the same quantity of
heat transported for a single phase loop (due to
heat of evaporation) => lower electrical
consumption from the pump, lower mass for
the system (lower diameter of the transport
lines, lower mass of the pump)
Allow a accurate temperature control (better
than 1C), this relatively independently of the
power transferred.
No heritage known with a complete system. A
loop should have been installed on ISS under
Russian responsibility but its development has
been interrupted.
No mechanical pump (work is provided per
capillarity) => higher reliability in the long
term
Heritage: Granat, Mars 96, Stentor
Loop Heat Pipe Similar to CPL but with a reservoir
More tolerant to NCG (unlike heat pipes)
Hybrid systems (CPL + Overcome critical phases such as start-up,
mechanical pump)
peak power loads
Table 3-23: Fluid loop systems
Table 3-24 shows the characteristics of working fluid selection:
Relative high mass and power consumption
Temperature of the fluid can only increase
while collecting heat through the acquisition
system.
Reliability of the system is mainly related to
the reliability of the pump
Sizing is more complex than single-phase
systems
Two-phase mixture difficult to predict and
test, possible instability
Physics of heat transfer sensitive to
acceleration
Reliability of the system is mainly related to
the reliability of the pump
Reliability of start up: medium to low
Pumping capability of the wicks (per
capillarity) is limited (