Selective Far Infrared Heating System—Design and Evaluation. I

Abstract

A novel far infrared (FIR) heating system was designed for selective heating of food powders such as soy protein and glucose. The FIR heating system consists of six ceramic lamps, a cone-shaped waveguide, and an optical band pass filter selected according to the spectral absorptivities of the chosen protein and glucose systems. A bandpass filter was used for differential heating of food components primarily due to their selective absorptivities. Selective heating of the two powders showed that protein, with an IR absorption range between 6 and 11 µm could be heated up to 6°C more in 5 min with the filter, compared to normal heating, when glucose temperature was higher than protein. Numerical analysis based on the different absorptivities of powders verified that the simulation results were very close to the experimental data with a maximum percentage error of 8.3%, confirming the feasibility of the heating system.