Non-dimensional Heat Release Rate Research Articles

Correlation of rate of gas temperature rise with mass loss rate in a ceiling vented compartment

n-heptane pool fire and industrial alcohol pool fire in a ceiling vented compartment were studied experimentally. The parameters including mass loss rate and rate of gas temperature rise were investigated. The results suggest that the rate of gas temperature rise, whose variations were highly coincident with those of the mass loss rate, minimized at the moment of extinction. The correlation of the rate of average nondimensional temperature rise with mass loss rate was established. It was found that the rate of average nondimensional temperature rise may be correlated with mass loss rate via the gas heat absorption coefficient which was found to be a quadratic function of the nondimensional heat release rate for the ceiling vented compartment under study. The present study may be of practical use for estimation of the time-dependent changes in mass loss rate from the gas temperature curves.

Flame Height of a Turbulent Diffusion Jet Flame with a Comparatively High Initial Discharging Velocity

A series of experiments was carried out in order to investigate the visible flame height of a jet flame with a high initial discharging velocity where the fuel-release time and mass flow rate of fuel were varied. The values of non-dimensional heat release rate (Q*) in present experiment were in the range of 107 Q* 8. Even if the value of Q* was larger than 106, when the non-dimensional number (RM) employed by Heskestad which implies the ratio of gas release momentum to the momentum made by a purely buoyant diffusion flame was less than 0.1, the flame height with a comparatively high initial discharging velocity increased with the heat release rate. In other words, whether flame height depends on the Q*2/5 or not can be decided by the range of momentum ratio (RM) regardless of the range of non-dimensional heat release rate (Q*). This can be also decided by the fire Froude number employed by Delichatsios.

An experimental study on the effect of ventilation velocity on burning rate in tunnel fires—heptane pool fire case

The 1/20 reduced-scale experiments using Froude scaling are conducted to investigate the effect of longitudinal ventilation velocity on the burning rate in tunnel fires. The n-heptane pool fires with heat release rate ranging from 3.71 to 15.6 kW are used in this study. A load cell is used to measure the mass loss rate of burning fuel and the temperature distributions are measured by K-type thermocouples in order to investigate smoke movement. The ventilation velocity in the reduced-scale tunnel is controlled by the wind tunnel through an inverter. The increases in ventilation velocity lead to enhance burning rate of n-heptane fuel. The reason is that the oxygen supply effect prevails rather than the cooling effect as the ventilation velocity increases. As a result, the heat release rates in experiment are larger than constant heat release rates by 4.45–11.3 times in the n-heptane pool fires. Also, it is found that non-dimensional critical ventilation velocity is proportional to one-third power of non-dimensional heat release rate.

An Evaluation of the Global Equivalence Ratio Concept for Compartment Fires: Data Analysis Methods

An experimental effort at Virginia Tech was initiated with the aim to evaluate the applicability of the Global Equivalence Ratio (GER) concept to compartment fires with prototypical building features. The present paper contains an in depth review of previous studies, which are contrasted with a new data set. The data are presented as integrate average mole fractions exiting the compartment correlated versus a new nondimensional heat release rate. In addition to presenting good correlations for depleted oxygen, carbon dioxide, carbon monoxide, and unburned hydrocarbons, the new parameter provides an indication of the degree of burning occurring up to the compartment exit plane.