Designing a peltier cooling system

[vrasp]

Hi all,

First of all, I m not sure where this thread should go. My apologies if this is the wrong section.

I'm currently studying solvent crystallization in materials and would like to create a discrete cooling system that I can place under a microscope to observe crystallization. To be more specific, I need to create a temperature gradient with freezing temperatures (ideally down to -30°C) on one side and room temperature on the other. After some research in the literature, I found exactly what I need:

https://hal.archives-ouvertes.fr/hal-01902742/document

Now, what they built is rather complex. Fortunately, I don't need the whole thing. The very first step and most important one is to build a system with two peltiers that are temperature controlled, connected with a temperature sensor to place on the material to be cooled.

I know the very basics of electronics and enjoy tinkering with stuff. My hopes was that you guys could help me answer some questions and guide me through the process.

I m gonna get the same peltier modules they got. The peltier modules are 3.9 A and 15.7 Vdc. The temperature controller they use is $1000. It's a TEC-1122 Dual Thermo Electric Cooling Temperature Controller. I m not sure why they got such an expensive device. My guess is that this is for lab use and it's super accurate which usually equals super expensive. This is not a requirement in my case.

Can I use a more reasonably priced temperature controller that has an output around 15Vdc ? I was looking at the inkbird ITC-106RL which is around $25. I would need two of them to control the two peltier modules.

I have more questions but I think this is a good start.

Thank you!

Vrasp

[diif]

No and it's complex as it needs to be. The water cooled silicon carbide heatsink looks interesting.

[vrasp]

That's too bad. Could you tell me what cheaper controllers don't have that make them inadequate for this project? If I can understand what exactly is required, I could try to find something in between.

In their setup, the authors were able to go from -25°C to +90°C. Honestly, if I can get to -10°C and keep the second Peltier at room temp, that's a start. Let's just say the aim of this project is to first see if I can build something that can create a stable temperature gradient. If it works, I can easily get the budget to set up something more efficient with a bigger temp range.

Any guidance would be helpful. Thanks!

Vrasp

[diif]

The TEC-1122 will provide power constantly to give precise control. the inkbird just turns on or off.
A pair of 30v 5A power supplies will give you the control you want, i think you'll need some sort of water chiller though.

[vrasp]

We have water-baths in the lab that I can hook up to a heat sink. Are you saying I could just hook up adjustable power supplies and just figure out the amperage needed to get to the temperature I need? Assuming a constant room temp and minimal effect from the heat transfer with the sample.

[diif]

Yes, I'd use adjustable power supplies. Aren't water baths heated ? There's a reason they've picked a chiller that goes to -5c.

[vrasp]

These waterbaths can go to negative temps. I 've actually been using one that goes to -15°C for my current experiments.

[diif]

Nice, I'm guessing you have power supplies already so just the heatsink to sort.