How do you calculate minimum ignition energy?

How do you calculate minimum ignition energy?

(1) E min = 1 6 πd 3 ρ b C av (T b −T u ) Here, ρb is the molar density of the burnt gas at temperature Tb (the flame temperature), and Tu the unburnt gas temperature (room temperature).

What does minimum ignition energy depend on?

Our results show that minimum ignition energy is strongly dependent on the ignition parameters, and a minimum value of 0.005 mJ is found for an ignition kernel radius of 0.0635 mm and an ignition time of 27.5 μs.

What is the minimum ignition energy of methane?

The minimum ignition energies of the methane/air mixture (all with 8.5% methane) decrease from 6.8 mJ to 0.4 mJ as the spark durations increase from 0.657 μs to 4.31 μs. The explosion pressure reaches the highest value when the spark duration is 2.627 μs and the minimum ignition energy is 1.3 mJ.

What is Mie value?

The Minimum Ignition Energy (MIE) value is used to assess the likelihood of ignition during processing and handling. It helps to define explosion prevention methods. MIE < 100 mJ indicates a potential for ignition from static discharges from personnel.

What is minimum explosive concentration?

The lowest concentration of a combustible dust in air, expressed in grams per cubic meter that will propagate a flame.

How much energy is in a spark?

According to the interwebs, the energy expended by the spark of a spark plug in an engine is 30 to 70 millijoules. If that spark is about 1 millimeter, then at the same current level and 10 times the voltage would be 300–700 millijoules, but a spark-plug size spark seems like more than you need to make a visible spark.

Which fuel has lowest ignition temperature?

Kerosene ignition temperature: 220oC.

Which of the following gas Vapour requires minimum energy for ignition?

The Minimum Ignition Energy (MIE) is the lowest energy required to ignite the flammable material in air or oxygen. The lowest value of the Minimum Ignition Energy is found at a certain optimum mixture….What are the values of MIE creating significant dust explosion risk?

Substance MIE (mJ)
butane 0.25

What is KSt and Pmax?

Kst value and Pmax are explosive properties measured in the laboratory to quantify the severity of a dust explosion.

What is MEC dust?

Minimum explosive concentration (MEC) is defined in NFPA 652 as the minimum concentration of a combustible dust suspended in air, measured in mass per unit volume (for example, grams per cubic meter), that will support a deflagration, such as an explosion or flash fire.

What is minimum ignition energy (Mie)?

Minimum Ignition Energy (MIE) ASTM E2019 Predicts the ease and likelihood of ignition of a dispersed dust cloud MIE of a flammable dust is the minimum spark energy needed to ignite an ideal concentration under lab conditions

What is the minimum electric spark ignition energy for iron dust?

For no propane in the air MEC for the iron dust was 200 g/m 3, whereas for 1 vol% propane it was 100 g/m 3. The influence of small fractions of methane in the air on the minimum electric spark ignition energy (MIE) for coal dust clouds was investigated systematically by Franke (1978).

What is the typical level of energy required to ignite mixtures?

In other words, much more energy is required when uℓ is low. The typical level of energy required to ignite the mixture in a spark-ignition engine is around 30 mJ.

What is the minimum electric spark energy of a dust cloud?

Minimum electric spark energies (MIE) for ignition of dust clouds vary, as already mentioned, with dust type, particle size, and other factors. In the past it was thought that the absolute lower limit for MIEs of dust clouds in air was of the order of 10 mJ, i.e. nearly two orders of magnitude above typical MIEs of IIA gases (see Chapter 2 ).