I'm currently researching if the project in my head could actually work. The project is as follows:
One side of a Peltier device on a aluminium block,
Other side of the Peltier device on a CPU fan,
Using a NTC thermistor to read the temperature value of the aluminium block,
Using a Arduino uno and its PWM signal to power the Peltier device,
Using a (MOSFET) H-bridge to change the current going through the Peltier device so instead of heating the aluminium block its gets cooled,
Using a program on the pc to bring the aluminium block to given temperature value's for different time period's.
So the program should be able to measure the temperature of the aluminium block and heat or cool to block automatically to the given values in the program itself.
Do you think that this is possible? Do i have to make the H-bridge myself or are their already manufactured ones?
I have to say that i don't have any experience with this kind of stuff.
Calypso:
Do i have to make the H-bridge myself or are their already manufactured ones?
There are lots of h-bridge drivers, and quite a few that are designed specifically for use with an Arduino. To choose a compatible driver you would need to know the voltage and current that you need to control.
There are several other posts on this forum describing similar projects. It is straightforward, but not a beginner's project.
Peltier devices usually run on 12V and consume up to 5-10 amperes of current, so you need a power source and H-bridge driver that can easily handle that current. Pololu has several brushed motor drivers that will work, like this one: http://www.pololu.com/product/1451
Finally, for reasonable efficiency you need aluminum fins on the side of the Peltier that the fan will heat or cool. A CPU cooler salvaged from an old computer will usually work.
The Peltier modules that I've worked with are symmetrical with respect to voltage polarity and heat transfer, so they work equivalently in either direction. I don't know of any that are not symmetrical.
jremington:
There are several other posts on this forum describing similar projects. It is straightforward, but not a beginner's project.
Peltier devices usually run on 12V and consume up to 5-10 amperes of current, so you need a power source and H-bridge driver that can easily handle that current. Pololu has several brushed motor drivers that will work, like this one: Pololu - VNH5019 Motor Driver Carrier
Finally, for reasonable efficiency you need aluminum fins on the side of the Peltier that the fan will heat or cool. A CPU cooler salvaged from an old computer will usually work.
The brushed motor driver from Pololu you suggested is compatible with Arduino?
Max current: 6A @ 12V
Suggested Voltage range: 12V to 15.5V
Maximum temperature differential (Tmax @ Qc = 0): 66°C
Maximum cooling power (Qcmax) @ 15.3V: 97W
127 Peltier elements
DC Resistance: 2.5 ohms
Silicone seal
Dimensions: 40mm / 1.57" x 40mm / 1.57" x 3.5mm / 0.13"
Wire Length: 339.72mm / 13.32"
Weight: 20.68g
Temperature cycles will be: start -> 94 - 98 degrees Celsius for x seconds -> 50 - 65 degrees Celsius for x seconds -> 75-80 degrees Celsius for x seconds -> Repeat from start +/- 30 times
Too strong for what? You control the rate of heat transfer by controlling the current flow through the Peltier, which is what the motor driver is for.
What i mean is that the heatsink assembly will get to -3,6 degrees Celsius or more and the temperature values of the aluminium block will be around 50 - 98 degrees Celsius, depending on program, so that is a bigger temperature differential of 66 degrees Celsius between the cold side of the Peltier and the hot side. Then the Peltier would work as great because its starting to warm its cooler side. So maybe i should look for a heatsink assembly that works around room temperature.
How are you deciding on those temperatures? At a given current flow, the Peltier module will sustain a maximum temperature difference between cold and hot, period.
If you cool down the hot side with a finned heat sink & fan, then the cold side can get colder, or vice versa.
