Title: AMS Tracker Thermal Control System TTCS Progress
1 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
2Content
- 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)
3System Design Issues Loop lay-out update primary
loop
4Primary 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
5System Design Issues Loop lay-out update
secondary loop
6Secondary 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).
7System 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)
8Condenser 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
9(No Transcript)
10Condenser 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.
11Mechanical New Condenser Design (schematic)
- Here 7x7 49 tubes are drawn.
- Preliminary thermal model calculations show this
might be reduced to 7x3 or 7x2 tubes.
12Mechanical New Condenser Design
Material Inconel 718 capillary piping Interface
material cho-term
13Mechanical New Condenser Design
Flat interface plate
14Mechanical New Condenser Design
Ribbed interface plate
15Condenser 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)
16Condenser 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.
17Condenser 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)
18Condenser 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)
19Condenser 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)
20Condenser 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
21- 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.
22Survival 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
23Survival 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
24Health 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
25health 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)
26Health 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
27Health 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
28Health 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
29Health 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
30Health 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
31Health 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
32Health 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
33Health 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
34Health 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
35Health 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
36Health 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)
37Health 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