AMS Tracker Thermal Control System TTCS Progress

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AMS Tracker Thermal Control System TTCS
Progress Design Issues TIM Meeting Houston,
18-23 October, 2004 NLR-team J. van Es,
M.P.A.M. Brouwer, B. Verlaat (NIKHEF), A. Pauw,
G. van DonkSun Yat-Sen University team Prof. Z.
He, Prof. K. Guo, Prof.J.Q. Ni INFN-AMS-team
Prof. R. Batiston, M. Menichelli
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Content

• System Design Issues
• TTCS Loop lay-out update (no volume enclosure
  possible)
• TTCS-USS interface temperatures (impact on
  start-up)
• Condenser design progress
• Radiator survival heater set-up, lay-out, number
  Pt1000s (TBD)
• health Control Loops (draft document available)
• Open safety issues (to be discussed/not presented
  here)
• TTCS filling procedure (impact on AMS
  Integration)
• No enclosures possible by the current loop
  lay-out (valves)

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System Design Issues Loop lay-out update primary
loop
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Primary Loop

• Number and location of control sensor locations
  fixed
• Implementation of a start-up heater to
• Account for start-up after power down without
  loosing the redundancy

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System Design Issues Loop lay-out update
secondary loop
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Secondary Loop

• Number and location of control sensor locations
  fixed
• Implementation of a start-up heater to
• Account for start-up after power down without
  loosing the redundancy
• Redundancy of the primary and secondary loop is
  made similar (except valves and LFM).

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System Design Issues TTCS-USS interface
temperatures (impact on start-up)

• USS Worst case hot temperatures impact the TTCS
  start-up flexibility
• Old values (BOL USS optical properties)
• TTCS-P TUSSnearBox 23.6 C
• TTCS-S TUSSnearBox 42.7 C
• New values (EOL USS optical properties)
• TTCS-P TUSSnearBox 59.4 C
• TTCS-S TUSSnearBox 50.3 C
• TTCS can start-up with Tbox,max20 C (accumulator
  at 25 C) (even TBC little margin in the box)
• During operation TTCS cools itself by the loop.
• TTCS start-up is therefore with current USS
  temperatures not possible in most orbits at EOL.
• MLI on the USS is proposed (CGS) to solve the
  problem (smaller a solar heat input)

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Condenser Design Progress

• Agreed with NASA/LM is high pressure tolerant
  condenser design allowing thawing (up to 3000 bar
  TBC)
• Derived thermal requirement for the radiator and
  liquid line temperatures. T(enclosed liquid CO2)
  lt 5 ºC This means by analysis Tradiator and
  Tliqlines lt 5 º C

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Condenser New Design

• Situate the connection between the parallel
  condenser tubing outside the freezing area
  (halfway the path to the TTCS-boxes)
• To cope with high forces/pressures that occur
  during thawing (after freezing) a condenser
  consisting of capillary tubing out of INCONEL 718
  is proposed.
• Number of parallel tubes will be optimised for
  weight, pressure drop and heat transfer.

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Mechanical New Condenser Design (schematic)

• Here 7x7 49 tubes are drawn.
• Preliminary thermal model calculations show this
  might be reduced to 7x3 or 7x2 tubes.

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Mechanical New Condenser Design
Material Inconel 718 capillary piping Interface
material cho-term
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Mechanical New Condenser Design
Flat interface plate
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Mechanical New Condenser Design
Ribbed interface plate
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Condenser Design Progress Overall (1/3)

• Strength-Stress calculations Inconell 718 tubing
• Pressures up to 3000 bar are feasible with
  acceptable thickness
• Calculation of optimum number of parallel tubing
• Required condensing area (Length, diameter,
  passages)
• Condenser Pressure drop contribution
• Calculations in progress (will be finalised when
  length is frozen) (see condenser_properties_design
  _20041015.pdf)

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Condenser Design Progress Pressure drop as
function of number of capillary tubes

• Pipe ID1mm, L10m
• Pressure drop decrease
• With the increasing of
• Pipe numbers.
• Increasing the length
• and the number of tubes
• will increase the whole
• condenser mass.
• The pressure drop mainly
• depends on the inlet
• condenser length.
• From system pressure
• drop, Npar should be
• larger than 28 when
• L10m, which is too long.

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Condenser Design Progress Overall (2/3)

• Condenser modelling and attached to detailed
  radiator model (model ready, implementation
  pending)
• Radiator temperatures will be calculated to check
  5 C maximum temperature during thawing (all
  orbits including transport to ISS)
• Investigate maximum position freezing front
• (calculate the radiator survival heater
  positions, thermostats, etc)

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Condenser Design Progress Overall (3/3)

• Update mechanical interface Condenser-Tracker
  radiator with 7 HPs (see Condenser update OHB)
• Investigation on manufacturing options connection
  tube-interface plate
• Possible options (stainless steel, Inconell 718,
  aluminium (preferred))
• Possible options are explosion welding between
  Inconell 718 and interface material (tubes are
  then connected to Inconell 718)

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Condenser design details Location of condenser
connection

• Location is defined by the maximum position of
  freezing front in the condenser tubing
• Approach
• Definition of number parallel tubes for heat
  transfer
• Modelling of the condenser tubing and incorporate
  in current TTCS Sinda model.
• Assumptions
• a. Tubes wrapped in MLI
• b. Free convection in tubing is neglected
• c. Detailed radiator model is used and
  incorporated in the TTCS-model
• Freezing front is defined in worst case cold
• Assumption
• A worst case estimate of the background
  temperature viewed by the MLI around the tubing
  is taken
• Check if the freezing front is at an acceptable
  location.
• If acceptable to NASA the location of the
  condenser connection can be frozen.
• If not a VF calculation between the MLI around
  the tubing and the AMS ISS surroundings is
  required.(will be a combined CGS-NLR analysis)

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Condenser Design Details Thermal calculations
for max Trad

• Approach
• Define the maximum temperature above freezing
  enclosed in the freezing parts of the condenser
  and frozen part of the condenser lines
• Gather information on maximum radiator
  temperature in power-down (already available at
  CGS) including
• transfer shuttle to final destination on truss
• on truss
• Make a worst case assumption of local solar input
  on the liquid lines (wrapped in MLI) and show
  TltTradmax
• Prove by analysis Tradmax --gt PltPmax
• Prove condenser and liquid line design is Pmax
  resistant
• mechanical analysis
• test
• focus on condenser exit

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• Radiator survival heater set-up, lay-out
• See Loop Lay-out for electrical (parallel)
  connection
• See ComponentsList21_09_04_V11.xls
• Due to HP-freezing (radiator temps lt 78 C)
  heaters should must cover (almost) complete
  HP-length
• Discussion with OHB of acceptable open areas
  between heaters on pipes.

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Survival heater details Pt1000s at radiator

• Needed for TTCS Electronics design
• Define the final number and location of Pt1000s
  on radiator (OHB)
• Pt1000s are required as Dallas sensors are out
  of temperature range on the radiator
• TTCS Electronics team proposes to read them by a
  the microprocessor, not to overload the FPGA

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Survival heater details Liquid line heaters

• Sizing approach (similar to freezing front
  calculation)
• Modelling of the condenser tubing and incorporate
  in current TTCS Sinda model.
• Assumptions
• a. Tubes wrapped in MLI
• b. Free convection in tubing is neglected
• c. Detailed radiator model is used and
  incorporated in the TTCS-model
• Heater power to heat up is defined in worst case
  cold
• Assumptions
• A worst case estimate of the background
  temperature viewed by the MLI around the tubing
  is taken
• Heating should be faster than radiator/condenser
  heating
• Heater is wrapped around the parallel tubing
  liquid lines (less dense at condenser connection)
• Heater power small (low heat capactity) and no
  heat loss to surroundings

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Health Monitoring Control Loops (proposed set-up)

• General
• On-board health controls will be limited to
  detection unsafe situations
• On-board will not comprise failure detection
  (will be performed on-ground)
• health controls may require action from
• TTCE (Thermal Tracker Control Electronics)
• JMDC
• PDS (via JMDC)
• Implementation of the health controls in TTCE or
  JMDC
• Implementation in TTCE is preferred as
• Fast response is required (limited thermal
  capacity in Tracker)
• health control must protect TTCS during short
  periods of unattended operation during JMDC-TTCE
  communication failures

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health Control Loops (proposed set-up)

• General
• Health Monitoring
• TTCE
• A health-flag (8-16 bit word) is proposed as a
  Health monitor.
• OK/Not_OK for the several Health limits
• Health algorithms have an update freq. 1 Hz
• JMDC
• JMDC will process health flag and take (to be
  defined) action(s)

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Health Control Loops (proposed set-up)

• Overview of Control Loops
• Overall Tracker electronics temperature Health
  control
• JMDC-TTCE communication Health control (in JMDC)
• Subcooling margin Health control
• Hot_Cold temperature difference Health control
• High temperature at pump inlet Health control
• Accumulator temperature Health controls
• Pre-heaters temperatures too high Health control
• Tracker too low temperature Health control
• Condensers temperatures out of limits Health
  control

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Health Control Loops (proposed set-up)

• Overall Tracker electronics temperature Health
  control
• Objective
• Protect Tracker electronics for too high
  temperatures (25 C)
• Rule
• If TTracker gt 25 C
• Action
• JMDC will switch-off Tracker electronics

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Health Control Loops (proposed set-up)

• JMDC-TTCE communication Health control (in JMDC)
• Objective
• Protect of Tracker against incorrect functioning
  of the TTCS, by switching off Tracker electronics
  after TTCE-JMDC communication outage
• Rule
• If TTCS_JMDC_Com_out_duration gt 10 (TBC) samples
• Action
• JMDC will switch-off Tracker electronics

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Health Control Loops (proposed set-up)

• Subcooling margin Health control (1/2)
• Objective
• Increase TTCE accumulator set-point to avoid
  vapour at pump inlet
• Rule
• If DT_subcool (T_acc-T_pump_inlet) lt Health
  margin 5 C (TBC)
• Action
• TTCE increases Taccu_setpointTaccu_setpoint
  TBD C

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Health Control Loops (proposed set-up)

• Subcooling margin Health control (2/2)
• Objective
• Switch-off pump in case of T_pump inlet
  temperature reaches T_accu
• Rule
• If DT_subcool (T_acc-T_pump_inlet) lt Health
  margin 2.5 C (TBC)
• Action
• Set pump to 0 RPM

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Health Control Loops (proposed set-up)

• Hot_Cold temperature difference Health control
• Objective
• Protect pump for cavitation in case of
  unacceptable low accumulator volume
• Rule
• If T_accu-T_meanloop gt 45 C (TBC)
• Action
• TTCE will set pump to 0 RPM

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Health Control Loops (proposed set-up)

• High temperature at pump inlet Health control
• Objective
• Protect pump for fluid flow close to critical
  point CO2 (avoid cavitation)
• Rule
• If T_pump_inlet gt 25 C
• Action
• TTCE will set pump to 0 RPM

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Health Control Loops (proposed set-up)

• Accumulator temperature Health control (1/2)
• Objective
• Protect Tracker Electronics from overheating
• Rule
• If T_accu_upper_operating_range gt 22 C
• Action
• JMDC switch-off electronics

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Health Control Loops (proposed set-up)

• Accumulator temperature Health control (2/2)
• Objective
• Prevent Accumulator to heat above Health limit
  (80 C)
• Rule
• If T_accu_temperature gt 79 C
• Action
• JMDC switch-off electronics
• Remark Obsolete as Health analyses will assure
  80 C is not reachable

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Health Control Loops (proposed set-up)

• Pre-heaters temperatures too high Health control
• Objective
• Prevent too high temperature at pre-heater
  location (in case pump is off)
• Rule
• If T_pre_heater gt 40 C
• Action
• TTCE switch off pre-heater power

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Health Control Loops (proposed set-up)

• Tracker too low temperature Health control
• Objective
• Prevent pumping too cold liquid in Tracker. Add
  additional power to stay within survival
  temperature window (-20 C)
• Rule
• If T_Tracker lt -16 C
• Action
• JMDC switch-on start-up heaters (on/off
  controlled)

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Health Control Loops (proposed set-up)

• Condensers temperatures out of limits Health
  control
• Objective
• Prevent freezing of condensers when PDS has
  powered off Health heaters. Alert JMDC command to
  command PDS to power-on survival heaters
• Rule
• If T_radiators lt -40 C (TBC)
• Action
• Alert JMDC to power on PDS survival heaters