Abstract: A heat flow measurement device is disclosed with an outflow conduit having an outflow fluid space and an outflow heat transfer surface and also with an inflow conduit having an inflow fluid space and an inflow heat transfer surface. The inflow heat transfer surface is thermally coupled to the inflow conduit and the outflow heat transfer surface is thermally coupled to the outflow conduit. A thermoelectric material is located between the inflow heat transfer surface and the outflow heat transfer surface and generates a signal that is proportional to the heat flux between the inflow conduit and the outflow conduit.