Calculation of Heat Pumped by Peltier

Peltier units are simply heat pumping devices and have really low COP compared to conventional vapor compression cycle based units. To estimate, how much amount of heat is pumped, I did a simple experiment. I bought a simple Peltier unit from Adafruit and glued it to a heat sink with thermal tape.

I put the heat sink in the measured amount of water (160 gm) and recorded temperature with TMP 35 sensor. Initial temperature of water was 31 deg C and final temperature after 300 seconds was 44 deg C.

Resistance of the Peltier was around 3.1 ohm from the current (2.6 A) and voltage (9.6 V) measurement.

  1. Amount of total energy energy dissipated (Qd) in water is 8706 J from m*Cp*(Tf-Ti)
  2. Energy supplied (E) over the 300 seconds was found to be 7488 J from V*I*t
  3. Heat generated to resistance (Qr) is small 21.9 J from I^2*R loss.
  4. Amount of heat removed from cold side = Qd – Qe – Qr = 1197 J or about 4 W
  5. This comes to COP = 4 W/(2.6 A*9.6 V) = 0.16

This calculation is rough estimate of the COP as thermocouple was +/- 2 deg C accuracy. Also this test does not indicate the performance of peltier in other operating conditions. It was done just to know how good is the peltier performance.

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