US Patent 7232255 System for measuring heat flow

The invention provides a system for determining the heat flow rate between a first and a second medium, the system including at least two sensor units having signal outputs disposed in a spaced-apart relationship, each of the units including a transducer having apertures allowing fluid to pass therethrough; the transducer of a first sensor unit is affixable to a first surface on the first medium, the heat flow of which is to be determined and a second surface of the first transducer is exposed to the second medium; a first surface of the transducer of a second sensor unit is affixable to a calibration plate, the calibration plate is affixable to the first medium, the heat flow of which is to be determined and the second surface of the transducer is exposed to the second medium; the signal outputs of the transducers are connectable to a processing unit for determining changes in the heat flow between the first and the second sensor units.