Quantitative IR Thermography for continuous flow microwave heating

The work here presented proposes an enhanced procedure to describe bulk temperature profiles in pipe flow subjected to microwaves, by means of on-line infrared temperature readouts. Such procedure is intended to overcome the well-known difficulties connected with temperature readings while microwave heating takes place. In facts, temperatures are usually measured onto few points by means of fiberoptic probes, which are often not reasonable for properly controlling the process at hand, as the electromagnetic distribution inside the cavity yields highly uneven spatial distribution of the temperature field. This study proves that looking inside the microwave oven through a metallic grid can be successfully realized, provided proper preliminary calibration procedures are in place. In order to assess whether the resulting temperature readouts are reasonable, experimental bulk temperature related to two temperature levels and two flow rates, are compared with numerical results obtained by running a 3D FEM model, developed by the authors. Experimental and numerical results were found in quite satisfying agreement.