Use of Peltier coolers as soil heat flux transducers

Peltier coolers were modified and calibrated to serve as soil heat flux transducers. The modification was to fill their interiors with epoxy. The average calibration constant on 21 units was 13.6 ± 0.8 kW m⁻² V⁻¹ at 20°C. This sensitivity is about eight times that of the two thermopile transducers with which comparisons were made. The temperature coefficients of the Peltier cooler transducers avg −0.034 kW m⁻² V⁻¹ °C⁻¹, whereas those of the two thermopile transducers were only 25% as large, relative to their calibration constants. The thermal conductivity of the Peltier cooler transducers was 0.4 W m⁻¹ °C⁻¹, which is comparable to that of dry soil. The cost of an unmodified Peltier cooler is around 20 dollars.