Thirdly, although hydrogen has
flammability limits of 4-75%, its explosive limits are different at 17-56%, and its very low vapour density means it will tend to dissipate harmlessly into the atmosphere (look at hydrogen vehicle fires online and see how well they compare to petrol!).
Caption: FIGURE 3 Classes of refrigerant flammability comparing the lower
flammability limits (LFLs) and burning velocity (BV) for various refrigerants.
The combustion characteristics were represented through the flame visualization,
flammability limits, and flame temperature.
Figure 2 shows a comparison between flame propagation limits measured with the 40 mm (1.6 in.) diameter vertical tube and
flammability limits measured with a 12 L (0.42 [ft.sup.3]) flask as specified in ASHRAE Standard 34 (2010).
The minimum ignition energies (MIE) are generally higher, the lower
flammability limits (LFL) are generally higher and the heats of combustion (HOC) are generally lower.
Another important parameter is the ratio of
flammability limits. In the combustor, the fuel and air must be continually burned to keep the engine running.
This time duration has been proved to be the most appropriate for
flammability limits measurements (Kondo et al.