Thermal Vacuum Chamber

1. SCOPE

A) Supply, Delivery, Installation, Commissioning, Training and After-sales support of Thermal Vacuum Chamber (TVC); 

B) Supply of Mechanical Compressor Cooling Systems and Liquid Nitrogen.

C) Liquid Nitrogen Exhaust & Vaporizer

2. TECHNICAL SPECIFICATIONS

 The TVC System will be used for thermal vacuum cycling to test if the satellite system can survive in the space environment. 

The schematic of the fully integrated TVC System. The “TVC System” or “System” means the Thermal Vacuum Chamber (TVC), Mechanical Compressor Cooling Systems,LN2 Tank and LN2 Exhaust & Vaporizer.

 2.1 Thermal Vacuum Chamber (TVC)

a) The TVC should be compatible with operation in a class 100k clean room environment. 

b) The Chamber body should be cylindrical in shape as shown as belows:

c) The thermal shroud internal dimensions, i.e. the working space of the TVC should be custom size based on your requirements.

d) The thermal shroud should house a base plate of size 800 mm (length) x 600 mm (breadth). The base plate should have an array of M6 X 1.0 mm mounting holes with a depth of at least 10 mm. The array shall have a pitch of 50 mm X 50 mm to mount the Device Under Test (DUT) onto the base plate. 

e) The base plate should be designed with rails which allows at least 50% of the base plate to slide out of the chamber once the chamber door is open. 

f) The chamber should be designed considering a DUT of mass 50 kg that has a maximum size of 350 mm (length) X 300 mm (breadth) X 300 mm (height) and a heat load of less than 200W 

g) The distance between the cleanroom floor and the top surface of base plate of TVC should be between 1000 to 1100 mm.

h) The angular displacement of door hinges should be more than 170 degrees. There should be a mechanical interlock to restrict the door from swinging back once the door is opened. 

g) The chamber body should be mounted horizontally on a supporting structure. 

h) The overall loading with any additional support structure for the TVC should not exceed 4 kN/m2 which is the limit for the designated area to house the TVC. 

i) The TVC should be able to be brought into the designated area through a door opening of size.Custom requirements will be negotiated

3. Illumination

 a) The chamber should be illuminated by lamp/LED with ON/OFF switch to observe the DUT through the view port.

4. Welding

 a) All welding processes and procedures involved in the System should be certified and compliant with ISO, GB, ASME or equivalent standards 

b) All joints (fixed and demountable) should be leak tested with HE-mass spectrometer. Leak rate must be less than 1 x 10-8 mbar litre/second. Test report should be provided.

5. Chamber Venting

 a) Under vacuum condition, venting should be achieved in less than 20 minutes by passing clean air through a 5-micron class filter. 

6. Control and Instrumentation System (CIS)

a) All the equipment such as vacuum pumps and drive motors should be controlled from CIS. 

b) Supplier should provide a suitable Personal Computer (PC) based Graphical User Interface (GUI) with all licenses in the name of National University of Singapore for the CIS. 

c) The GUI of the CIS should fulfill the following tasks: 

i. Display temperature of the DUT, shrouds and base plate

ii. Display pressure of the vacuum chamber

iii. Display functional status of all System components and safety interlocks

iv. Display the state of main process regulation loops such as shroud temperature control

v. Display temperature profiles of shroud and DUT with proper scaling as a function of time

vi. Custom program generation, storage and execution 

d) There should be a fully automated computer controlled start up and shut down of the System. 

e) The CIS should acquire data from the temperature sensors on the shrouds, base plate and DUT as well as the data from the pressure sensors of the chamber. 

f) Data logging should have a failsafe mechanism that prevents any loss of test data during power/System failure. 

g) Salient features of CIS Hardware/Software: 

i. Data acquisition period should be programmable through the GUI of the PC system

ii. Data should be recorded at a sampling time of at least 1 second

i. Acquisition and recording of data should last for a duration of at least 365 days

7.Thermal Control System (TCS)

a) The thermal control system (TCS) for the TVC should be capable of handling a DUT mentioned in 2.1f.

b) The TCS should consist of: 

i. One (1) cylindrical shroud

ii. One (1) front circular shroud

iii. One (1) back circular shroud

iv. One (1) baseplate

v. Embedded heaters on the shrouds and base plate, rated at 10.0 kW or more. An example of the distribution of heaters is as follows:

· 5 kW on the cylindrical shroud

· 2 kW on the front and back circular shroud

· 3 kW on the base plate 

c) The temperature of the shrouds and the base plate of the chamber should be controlled by embedded heaters for heating and with Liquid Nitrogen (LN2) for cooling.

d) The temperature of the shroud and the base plate should be controllable within the range of  -190 °C to +200 °C. 

e) Temperature ramp rate during heating should be +2 °C/min or faster. 

f) Temperature ramp rate during cooling should be -2 °C/min or faster. 

g) Outgassing requirement of the shroud and base plate for space environment application are given below as per ECSS-Q-70: 

i. Outgassing:· % Total Mass Loss (TML) : < 1· % Collected Volatile Condensable Material (CVCM) : <0.1 

h) TCS should have the following independent temperature control channels for heating and cooling. The distribution of these channels should be as per shown in Table 1.

Table 1: Number of channels for Thermal Control System 

i) TCS should have two (2) modes of thermal control:Automatic control mode and Manual control mode 

j) Under automatic control mode, the shroud temperature and base plate temperature are automatically controlled by the set point temperature defined on the DUT, cooling via LN2 and heating via embedded heaters. The injection of LN2 and heater power to control the shroud temperature should be automatically controlled through a computer with GUI program to the pre-defined set point temperature as per programmable thermal cycle profile. Each control loop should have its own programmable thermal cycle profile. 

k) Under manual control mode, the shroud temperature, base plate temperature, heater power and user added external heater power should be controlled by the user through a computer with GUI program following a programmable set heater power and temperature profile. 

l) There should be sufficient thermocouples  attached to the shroud and base plate to measure their temperature. Average reading of these thermocouples should be used for thermal control. The readings from these thermocouples should also be used to measure the uniformity condition.

m) User should be able to set the DUT set point temperature based off One (1) thermocouple or an average of at least Ten (10) thermocouples.

7. Temperature Sensors and Instrumentation

a) GRANDETOP®  should use IEC (International Electrotechnical Commission) standard to select temperature sensors. 

b) There should be at least twelve (12) class-1 T-type thermocouples or PT100 platinum resistance thermometers (PRTs) for temperature control (8 on the shroud and 4 on the baseplate). 

c) There should be at least twenty (20) class-1 T-type thermocouples or PT100 platinum resistance thermometers (PRTs) for temperature monitoring of the DUT. 

d) At least one (1) class-3 T type thermocouple or PT100 platinum resistance thermometer (PRT) must be installed on each inlet and outlet manifold of thermal circulation system for diagnostic purposes. 

e) Thermocouples connected to the CIS should pass through specialized thermocouple feedthroughs. (Note: Feedthroughs mentioned in section 2.1.1 are reserved for USER DUT and will not be used for temperature monitoring and connection to the CIS.)

8.Vacuum System

a) The vacuum system should have a pump down time of less than 600 minutes to reach a vacuum condition of 1 x 10-5 mbar or lesser from the ambient condition without a DUT. 

b) The vacuum system should have at least two (2) vacuum gauge/gauges installed at appropriate locations to accurately measure the vacuum level of the chamber.

c) The vacuum level of the chamber should be within the tolerance defined in Table 2.

Table 2: Maximum allowable tolerance of pressure in vacuum chamber

8.Vacuum Pump Exhaust

a) A vacuum pump exhaust without suction fan is provided.Customer should review the existing exhaust providedduring the site visit for compatibility

with their proposed System.

Please kindly feel free to contact us for more details.