environmental chamber project

[derZockerMP]

Hello, this post is a follow up of this thread:  https://www.eevblog.com/forum/projects/environmental-chamber-build-idea
I'm building my own environmental chamber.



The project approach was to sweep the temperature from 10°C to 40°C with a 20W max thermal load inside. The chamber itself uses an old styrofoam box with inner dimensions of 40 x 30 x 25 mm to easily fit a Keithley or other instrumentation inside.



The Peltiers are four cheap Chinese ones connected 2 in series and 2 in parallel to get the drive voltage to 24V. The cold side heatsink is embedded in the styrofoam top part and isolated with foam around it. Air circulation is managed with a 120x120 mm fan to keep everything at the same temperature. There is a connector at the top for the PT100 temperature sensor.
To cool the hot side, a big heatsink handles nearly 200W, assisted by four fans.



For the PID control side, a TCB-NE-AH is used, capable of delivering 18A at 24V. The power comes from a MeanWell 400W power supply with active cooling at the back. Another 12V power supply is for the fans. You can control the speed with two potentiometers and switch the fans and controller on and off with a switch. Three status LEDs indicate on state, operation state, or if an error has occurred. The TEC is controlled by a serial port on the back via nice software called TCB-View or a self-made Python script.




The settling time of the whole regulation path is around 20 minutes to stabilize to ±0.05°C. The oscillation is rather short, with around two cycles around the set point. Some graphs are coming soon. If you are building your own, make sure not to make the same mistake and choose the PT100 version. Due to long wires and connector resistance, the error is around 7°C off the actual temperature. Self-heating is also a problem. Thankfully, the offset can be canceled out by software. So, please use PT1000 instead.

Feel free to ask if you have any questions about the project.

Thanks,
Stefan

[Overspeed]

Hello

Nice project , you perhaps need to make a TUS ( temperature Uniformity Survey )  by using 5 sensors ( Pt100 or Thermocouple T ) sensors are fixed on a light cube frame ( no thermal inertia ) one on each corner and one in the center , this type of measurement is in use on AMS 2750 , that allow to check if your internal volume is uniform in temperature as your heating /cooling is on the box lead .

Regards
OS