Timewise temperature control with heat metering using a thermoelectric module

A thermoelectric module was adapted to (1) control the face temperature of an aluminium sample as a function of time, and (2) measure the associated instantaneous rate of heat transfer into the sample. Proportional (P) or Proportional-Integral-Derivative (PID) controls were applied. With respect to time, constant temperature, sinusoidal and triangular temperature variations were tested. These temperatures were well within 0.1 K of the set point (one standard error). Tests on square wave temperature variation indicated the limitations of the module heating and cooling power. For the range of temperatures explored, the thermoelectric properties of the module were found by fitting predicted temperatures to experimental measurements (the module electrical resistance was taken from the manufacturer's data). Associated uncertainty, typically ±10% of total heat flow at 12 W, was far bigger than the ±2% for heat flow meters assessed against National Institute of Standards and Technology (NIST) calibrations; nonetheless the temporal resolution (3 readings per second) offers some useful insight into thermal processes.