CH 8: Ignition

Question 1

What is ignition temperature?

Answer 1

Minimum temperature required for ignition of fuel gases under specific test conditions

Question 2

What is the piloted ignition temperature?

Answer 2

Temperature required to produce the lower flammable limit and can be ignited in the presence of a piloted ignition source

Question 3

What is the autoignition temperature, (autogenous ignition temperature)?

Answer 3

Temperature at which oxidation reactions will initiate within fuel/air mixtures without an outside pilot source

Question 4

A view factor method:

Answer 4

approximates the flame as a geometric shape and uses an average emissive power of the geometric object to estimate the heat flux to a target.

Question 5

Which of the following is NOT a material property that influences both ignition and flame spread?

Answer 5

Moisture

Question 6

Which of the following thermophysical properties are termed thermal inertia?

Answer 6

Density, specific heat, and thermal conductivity

Question 7

In geometry of fuels, which shape of fuel surface will reflect the LEAST imposed heat flux?

Answer 7

Convex

Question 8

In the orientation of solid fuels, which will typically have slower flame spread under identical conditions?

Answer 8

Horizontal

Question 9

The flow of the heated gases, and thus the convective heat transfer, aiding in the flame spread is known as:

Answer 9

concurrent flow flame spread.

Question 10

The flow of air entraining into a combustion reaction that is going against the spreading flame is known as:

Answer 10

counterflow flame spread.

Question 11

What is the term for the inability to absorb heat energy very well, resulting in quickly transferring heat from one side to the opposite side of the material?

Answer 11

Thermally thin

Question 12

What is the term for solids that absorb heat energy more readily and do not transfer it as quickly through the material to the opposite side?

Answer 12

Thermally Thick

Question 13

A temperature increase in a thermally thin item, that begins to occur based on the severity of the heat exposure and the duration of this exposure and the fuel’s material properties, can be calculated by which of the following formulas?

Answer 13

T = T infinite + q(t)/pcl

Question 14

In response to a temperature increase in a thermally thin item, by which of the following formulas it is possible to calculate the time it takes for ignition based on the imposed heat flux and the material properties?

Answer 14

T=t infinite + q(t)/pcl

Question 15

In response to a temperature increase in a thermally thick item, by which of the following formulas it is possible to calculate the time it takes for ignition?

Answer 15

T=T infinite + q(t)/pcl