Heat Release Rate (HRR)
Definition - What does Heat Release Rate (HRR) mean?
Heat release rate (HRR) is the rate of heat generation by fire. It is typically measured in Joules per second or Watts, since the output of a fire can generate more than a watt. For easier quantification, megawatts or kilowatts are used.
HRR is the heat that is available in every square foot of surface absorbing heat within a particular surface.
Corrosionpedia explains Heat Release Rate (HRR)
The calculation of heat release rate is highly beneficial in various industries, especially in commercial aircraft. It was in the 1970s that the first method to measure HRR was discovered. This was followed by various testing methods and devices until the cone calorimeter was invented in 1982. This remains the standard device for measuring HRR.
There are several ways to calculate the heat release rate of a material. A good approximation can be determined by the formula:
qHc = ΔHc x mfuel
qHc = the heat release rate (kJ/s)
ΔHc = the heat of combustion (MJ.kg-1)
mfuel = the mass flow rate of the fuel (g/s)
The HRR is not simply a variable used to characterize fire. In fact, it is the solely significant variable in defining phenomena such as a fire hazard. Heat release rate is the driving force in terms of fire. Hence, the production of undesirable effects of fire and its products also elevates with increased HRR. This means that toxic gases, smoke and other types of fire hazards increase in parallel with the heat release rate.
By cautiously monitoring HRR, threats to life and property can be prevented. Thus, strict monitoring should be implemented by industrial operators to prevent fire hazards.