How a divided bar works

A divided bar applies a known temperature differential across a rock sample in series with a material of known thermal properties. A conventional divided bar maintains the temperature differential using thermostatically controlled water baths. These baths are bulky and (usually) require a source of running water to cool the pump motors. In contrast, the PEDB maintains the temperature differential at ± 0.01°C with high stability using electronic Peltier devices, which heat or cool in rapid response to an applied electric current. The PEDB requires no external cooling.

The thermal conductivity of a rock sample is measured using any divided bar by determining the ratio between the thermal gradient across the rock and that across the known material under steady-state conditions.  The PEDB can also be used in a ‘transient’ mode to measure volumetric heat capacity by determining the amount of heat absorbed by the rock sample as it warms (or cools) from one steady-state temperature to another.