Choosing the Heating and Cooling Element
Now that our setup for recording current temperature and accepting user input for set temperature along with displaying these both on the LCD was complete, it was time to decide what component we will use for heating and cooling.
Initially we had planned about using a Nichrome wire for heating application, but some research for a cooling element shifted our focus on a Peltier Element which was capable of offering both cooling and heating!
About Peltier Element:
Peltier Element also known as a Thermo Electric Cooler is a semiconductor technology that concentrates the heat on one of its face making the other one cooler. Therefore one of the sides being extremely warm and the other one being extremely cold.
The polarity of the supply decides which face is warm or cool. Reversing the polarity makes the warmer side cool and vice versa.
The peltier works on a 12 V DC supply but draws a large current. The peltier we’ll be using (TEC 12706) in our project has a capacity to draw 4 A Current for maximum Heating/Cooling. The amount of current it draws decides the magnitude of Heating/Cooling it can provide. Thus the amount of temperature change that we want can be controlled by controlling the amount of current supplied to it.
Heat Sinks :
The efficiency of how cold a side of the peltier gets depends upon how efficiently the other side of the device dissipates the heat. Thus there is a requirement of a heat sink and a fan to dissipate/spread the heat on one of the faces.