Hi all. I am currently working on a senior design project involving the use of Peltiers. The goal is to use them to cool the ambient air so that the cooler air can be inhaled in an attempt to lower the body's core temperature. We realize that the body stores heat well so if there is any temperature difference at all, it will be small. Our professor just wants to see if it will work.
The main thing I need is assistance with suggestions on powering it. The system will include four 30mm x 30mm x 3.8mm TECs with a max current of 6.0A, Vmax of 8.6V, and Ron of 55 mOhms (28.7 W). The TECs will be mounted to one side of a rectangular copper pipe that the air will pass thru. They will be placed side by side in one column. The system will have an intake fan at one end of the housing to move the air through the copper pipe. We are using an Arduino Uno and a simple LCD to display the temperature of both the ambient air and the cooled air.
We plan to power the TECs and intake fan with a 12V DC battery (design criteria was portability). However, I recognize the Arduino needs a 5V input. For now, I have a separate 5V, 1A rechargeable battery for it. Anyways the goal is to be able to adjust the power delivered to the system in order to adjust the temperature of the air. I have read that a MOSFET with appropriate resistors and PWM would be the simplest solution. However, another option that seemed to be a possibility is an ESC (brushed or brushless). I am not sure, our BME professor hasn't been much help on the electrical side of things. Any suggestions would be greatly appreciated.
Also I can include links to sketches/drawings and any of the components we have already selected. Many thanks for reading this far.
If I read Your qeustion properly the number of sensors and output is rather okey. Any Arduino would handle it.
For output currents higher than 20 mA, use logic N-channel MOSFETs. Yes, a 100 or 1000 Ohm resistor is recommended between the Arduino and the MOSFET.
What's "ESC"? Usual motors are handled like any heavy load. Using PWM is possible if not a simple turn on/turn off control will do the job.
You have to transfer the heat from the hot Peltier side to another place, else the ambient air only becomes hotter by the power flowing into the Peltier element (6A*8.6V > 50W).
If you try to cool that in the air you're going to burn our hands on a hot pipe. Forget the electronics and power issues, you need to first work on a way to dump all the heat your going to generate. Think water jacket..
From the specs it looks like you are talking about the TEC-30-36-71. Is that something you can change? The datasheet says "Do not exceed Imax or Vmax when operating module". I think that means a 12V battery would be a bad choice for an 8.6V device. I guess you could use two in series to make a 17.2V device but maybe one of the 15.4V models would be a better choice.
How long do you want this thing to run on battery power?
You don't need a motor controller (H-bridge or Brushed DC ESC) if you are only cooling air. An N-Channel MOSFET between the negative side and Ground will be sufficient to PWM the cooling.
Have you determined how many watts of power you have to remove from the incoming air? I would worry that it would require cooling the air to sub-freezing temperatures and that might be bad for the lungs.