Experimental and Numerical Investigation of Fire Dynamics Inside the Closed Enclosure

Experimental and numerical studies have been conducted in an enclosure of size 4m x 4m x 4m to determine burning characteristics and the thermal environment inside the closed enclosure. The fire source is a 60 cm diameter isopropanol fuel placed in the center of the enclosed space. The thermal environment was measured along the enclosure's heights and at the longitudinal orientation of the ceiling. The highest temperatures recorded at roof locations C1, C6, C11, and C16 were 175 degrees C, 182 degrees C, 190 degrees C, and 177 degrees C, respectively. Initially, the mass loss rate increased with time, reaching a maximum value of 25.5 g/m2 2 s before decreasing with time. The rate of release of energy is a key parameter that needs to be known for the proper design of the fire protection system. In the present study, the enthalpy balance method was used to predict the rate of heat release. The maximum deviation of heat release rate between the experimental and predicted enthalpy balance was found to be about 20%. Energy transfer to the enclosure surfaces was found to occur at a rate of about 91.2% of the total energy released, whereas energy transfer to gases occurred at a rate of 9.8% of the total energy losses. Numerical studies were performed using the Fire Dynamic Simulator (FDS) to investigate the local characteristics of fires. Isopropanol's Limiting Oxygen Concentration (LOC) was found to be 11 vol.% under stoichiometric conditions. The self-extinction time was observed at 840 s from the ignition which is in good agreement with the semi-empirical equation proposed at different studies.