Peltier module, TEC1-12706
A thermoelectric cooler: current pumps heat from one ceramic face to the other, so one face cools and the other heats up.
Aliases: TEC1-12706, Peltier element, thermoelectric module, TEC. It is the part in mini fridges, cup coolers and cloud chambers. It has no moving parts and no polarity marks except the leads: red to +, and the face with the part number printed on it goes cold.
Pins
| Pin | What it does |
|---|---|
+ (red) |
Current in here cools the printed face. |
- (black) |
The return. Swap the two and the printed face heats instead. |
The datasheet
The HB Corporation sheet, with the hot side at 25 °C: 50 W of heat pumped at most (with no temperature difference), 66 K of temperature difference at most (with no heat pumped), 6.4 A and 14.4 V at most, and 1.98 Ω. The highest operating temperature is 138 °C.
At 12 V it draws about 6 A from a cold start, falling to about 4.5 A as the faces pull apart, so it hangs off a logic-level MOSFET (an IRLZ44N or a D4184 module), a relay or a solid-state relay, and the supply has to give 6 A. A board pin cannot run it.
The heat sink is the whole design
Every watt it pumps, plus the 55 W or so it burns at 12 V, comes out of the
hot face. With a good cooler (the default heatsink of 0.5 K/W, a CPU cooler
with its fan running) and nothing on the cold face, it settles in a few
minutes with the hot face near 54 °C and the cold face near -9 °C in a 25 °C
room. With a poor one the hot face climbs, the cold
face follows it up, and past 138 °C the module is ruined: the simulator
reports it overheated and it goes open. That is what a real one does when it
is run without a heat sink, in well under a minute.
Properties
| Property | What it sets |
|---|---|
ambient |
The room, 25 °C by default. |
heatsink |
The hot face's heat sink to the room, K/W: 0.5 by default. A bare aluminum plate is 2 to 5. |
hot_mass |
The heat sink's heat capacity, J/K: 150 by default. |
cold_mass |
What the cold face is cooling, J/K: 40 by default, about a 45 g aluminum block. |
insulation |
The cold side's leak to the room, K/W: 10 by default. |
The probe and the readout are the cold face's temperature.
How it is modeled
The standard one-stage module model, its three constants from the 25 °C
column: a Seebeck coefficient of 14.4 / 298 = 0.048 V/K, the sheet's 1.98 Ω,
and a thermal conductance of 0.54 W/K. The heat pumped out of the cold face
is S I Tc - I² R / 2 - K ΔT, the heat into the hot face is
S I Th + I² R / 2 - K ΔT, and the terminal voltage is I R + S ΔT, so a
module working against a large temperature difference draws less current
from the same supply, as a real one does. The textbook model gives 51.5 W and
61 K against the sheet's 50 W and 66 K.
What it cannot do here
No other part feels these temperatures. A DS18B20, an NTC or a TMP36 on the bench reads its own slider, not the cold plate, so a thermostat sketch can switch the module but cannot read it. The hot face's temperature is not shown either, only its overheating. The constants are the 25 °C ones throughout (a real module's resistance rises to 2.30 Ω at 50 °C), and condensation and ice on the cold face are not modeled.