User Tools

Site Tools


thermal_vac_chamber

Project Description

In order to simulate the conditions of high altitude flight we must either buy or build our own thermal-vac chamber. Since commercial ones cost more than $10k, we will be designing, and building our own low cost thermal-vac chamber.

Design

Concept Overview


Step 1 concept_1.jpg

  • Place electronic parts into the chamber, minimize thermal conduction (possibly hang parts with fishing strings)
  • Close the chamber
  • Purge the chamber with dry nitrogen, allow air inside to exit
  • Allow the chamber to consist of mostly dry nitrogen

Step 2 concept_2.jpg

  • Close off all values to the chamber
  • Place dry ice around the chamber to cool the dry nitrogen and electronic parts through thermal convection
  • Measure temperature inside the chamber and the temperature of the electronic parts
  • Allow it to achieve -60C

Step 3 concept_3.jpg

  • Open the value leading to the refrigerator pump
  • Pump the -60C dry nitrogen until the pressure is at 1010 Pa (pascals) or 0.01atm (1% of pressure at sea level) (estimate pressure at 100,000ft)
  • The chamber is now simulating the environment of 100,000 ft (-60C and 1010 Pa)

Mechanical Overview


The Thermal Vacuum Chamber concept consists of single 1/4“ thick aluminum tube with a 7.5” ID and 8.0“ OD. We then place a 1/4” aluminum plate on one end and 1/2“ acrylic on the other end. We will also add a hole on the bottom aluminum plate to allow wires to pass. All joints are sealed with low temperature liquid gasket.

Tubes available here: https://www.speedymetals.com/pc-4661-8371-8-od-x-250-wall-tube-6061-t6-aluminum.aspx

Conceptual drawings of the environmental test chamber:

Mechanical Stress Analysis


The following is a stress analysis of one of the walls. It's fixed by the corners and a 14psi pressure load is applied to the wall (at room temperature). Results conclude that deflection is minimal, however more materials should be looked into.

Full analysis report: Cylinder: cylinder-simulationxpress_study-1.docx

Bottom Plate: bottom-simulationxpress_study-1.docx

Electronics

  • 6 Low Temperature Thermocouples
  • Pump Controller
  • Pressure Sensor

Software

  • None
thermal_vac_chamber.txt · Last modified: 2013/08/13 12:13 (external edit)