Smoke Detection Using rGO-Coated eFBG Sensor for Early Warning of Coal Fire in Mines

This experimental work demonstrates the process of smoke detection in coal mines using reduced graphene oxide (rGO) coated on etched fiber Bragg grating (eFBG)-based sensors. The lab experiments were conducted using the test fire of combustible coals collected from the different geographic regions of coal mines in Jharkhand and West Bengal in India. The experimental results showed that the coal samples higher in carbon elements interacted with rGO on fiber more strongly. Obtained results show that the increment in the shift of reflected Bragg wavelength with respect to air was observed by exposing the sensor head to the smoke particles inside the smoke chamber. The percent enhancement in the Bragg wavelength shifts are found to be 18.82%, 30%, and 34.74% in Ramnagar, Jharia, and Bokaro, and the sensitivity has been achieved by bare eFBG is ~104.32 pm/sample and by the rGO-coated eFBG sensor is ~134.33 pm/sample. Other parameters like gross calorific values (GCVs) of different coals are also measured using proximate analysis and also directly through a bomb calorimeter. The reported sensor can be installed in coal mines for early fire warning detection.