🌡️ 2A — Heat, Temperature & Heat Release

What is heat?

Thermal kinetic energy that helps release the potential chemical energy stored in fuel.

Products of combustion

the process of fuel changing its chemical composition to produce new substances

what is incomplete combustion and what can be an example of incomplete combustion?

Smoke and ash; combustion is incomplete when any fuel is left after combustion has occurred

examples of carbon based fuels

Wood; cotton

examples of hydrocarbon fuels

Plastics, Synthetics fabrics, etc.

what is asphyxiation

the fatal level of oxygen deficiency in blood which can be caused by the concentrations of products of combustion and/or low oxygen.

carbon monoxide

colorless, odorless gas present at almost every fire. released when an organic material burns in an atmosphere with a limited supply of oxygen

what is hydrogen cyanide

a toxic and flammable substance Produced in the combustion of materials containing nitrogen

Materials that can produce HCN (Hydrogen Cyanide)

Fibers such as wool, cotton, and silk

Resins such as carbon fiber or fiberglass

Polymers such as nylon or polyester

Synthetic rubber such as neoprene, silicone, and latex.

Carbon Dioxide (CO2)

product of complete combustion of organic materials.

What is temperature?

A measurement of the average kinetic energy of particles in a sample of matter.

Is temperature an accurate measurement of heat transfer?

No. Temperature alone does not accurately indicate the rate of heat transfer.

Is temperature an accurate measurement of heat transfer?

No. Temperature alone does not accurately indicate the rate of heat transfer.

What is heat release rate (HRR)?

The amount of energy released per unit of time as a fuel burns.

What units are commonly used for heat release rate?

Kilowatts (kW) or megawatts (MW).

What is heat flux?

The flow of energy to a unit area, measured in kilowatts per square meter.

Why is heat flux important to firefighters?

It provides a better indication of how long PPE will protect a firefighter than temperature alone.

What are three common sources of thermal energy?

Chemical, electrical, and mechanical energy.

What is self-heating?

A form of oxidation in which a chemical reaction increases the temperature of material without an external heat source.

What is spontaneous ignition?

Ignition that occurs without the addition of external heat.