Image Number 3 for United States Patent #6264362.
Apparatus for and methods of meauring heat flux comprises first and second sensors arranged to pass through an oven in line astern. Each sensor measures the temperature difference across a thermally insulating layer by having one surface of each sensor being exposed to the heat flux, each sensor including thermocouple measuring junctions for measuring the temperature of the exposed surface. The first sensor is radiation-absorbing and the second sensor is reflecting. The apparatus includes additional thermocouple junctions for measuring the gas temperature and a device for recording data from the sensors and from additional thermocouple junctions. The signals from one of the sensors at one instant are correlated with the corresponding signals from the other sensor at a later instant, the time difference being the time taken for one sensor to reach a position formerly occupied by the other sensor.