Temperature sensing in microwave heating of concrete using fibre Bragg grating sensors

Abstract

Temperature is an important process control, but is a difficult parameter to measure in the microwave processing of concrete. Owing to their metallic nature, conventional thermocouples are not suitable for temperature measurement in microwave fields. Some of the most popular sensors known to be immune to electromagnetic interference are based on optical fibres. This paper presents the results of an experimental study conducted to investigate the capability of fibre Bragg grating (FBG) sensors to monitor the surface temperatures of concrete specimens during microwave heating. A thermo-tracer camera was used to verify the accuracy of the FBG measurements. Moreover, the FBG measurements were compared with the results of numerical modelling and measurements taken using conventional thermocouples. The results show that the bare FBGs deployed in this study can be used to accurately measure concrete temperature in a microwave field.