Week 2 Forum – Heat Release Rate
The heat release rate is the single most important variable in a fire. Generally, the heat release rate provides fire service professionals a way to quantify and intelligently discuss the complexity of fires, including their size, potential impact, and correlation with other variables.
Once you complete the Week 2 readings, write a post to achieve the following:
1. Define heat release rate.
2. Discuss the importance for the fire service professional to understand and recognize heat release rates and its measurement.
3. Discuss two ways heat release rate is measured.
4. What did you find from your research and the readings to be the most interesting aspect of the heat release rate?
In this weeks forum we were asked to define heat release rate. Heat Release Rate is best defined as the rate at which fire releases energy (NIST, 2010). Heat Release Rate is also known as power (NIST, 2010). It is imperative for firefighter to understand and be able to recognize heat release rate. The heat release rate as we learned in our reading this week causes power. The heat release rate when recognized properly can help responding firefighters to determine the size of the fire, the complexity of the fire and the potential safety impacts from the fire. Obviously if the heat release rate is lower there is less of a risk for firefighters and quickly extinguishing the fire utilizing proper fire ground tactics is a safe technique for all involved in the firefighting efforts. As we discussed in the week one forum being able to understand and recognize the heat release rate can determine how the fire is going to be suppressed wither utilizing and aggressive attack, a transitional attack or a defensive attack. I discovered in the week two lesson that there are two methods of measuring heat release rate. One way is to estimate the heat release rate by calculations. The second way to determine heat release rate is to test fuel items and measure the heat release rates. As we can see via videos in or week two lesson as well as numerous videos on line differently constructed materials release different heat release rates. I believe what I found most interesting item from this weeks lesson and the information provided in reference to heat release rate are the math calculations needed to measure different heat release rates. I have often found math to be confusing and this weeks reading proved no different. I believe that I would prefer utilizing testing methods and video reviews to determine the release rates before having to depend on math calculations.
Jiahao Liu, & Mingyi Chen. (2018). A Simplified Method to Predict the Heat Release Rate of Industrial Nitrocellulose Materials. Applied Sciences, 8(6). https://doi.org/10.3390/app8060910
Zou, G., Huo, Y., Chow, W., & Chow, C. (2018). Modelling of heat release rate in upholstered furniture fire. Fire and Materials, 42(4), 374–385. https://doi.org/10.1002/fam.2502
This week we are asked to define heat release rate, discuss the importance for the fire service professional to understand and recognize heat release rates and its measurement, discuss two ways heat release rate is measured, and to expand on what we found interesting about heat release rate in this weeks reading.
Heat release rate is defined as “…a critical parameter for the evaluation of compartment fire growth that is incorporated to a wide range of fire assessment tools, ranging from simple hazard indexes to complex computational fluid dynamics modeling. Analytical formulations, empirical correlations, Zone and Computational Fluid Dynamics (CFD) models use the HRR as an input parameter to determine almost every other quantifiable variable with respect to the fire.” (1166) According to the Calculation Methods for the Heat Release Rate of Materials of Unknown Composition from this weeks assigned readings.
It is exceedingly important for the firefighter to understand HRR because it will shape the way we attack the fire. Additionally, it is important to understand that depending on the progression and location of the fire it might be hard to tell what types of materials are involved. That is why I found the article Calculation Methods for the Heat Release Rate of Materials of Unknown Composition so interesting, this article states there are two main ways HRR is calculated, “The most widespread techniques are based on mass balance. If the heat of combustion of the fuel is known, the measure of the mass loss allows its evaluation. If the burning material can not be identified, calorimetric principles can be used. They rely on oxygen consumption (OC) or carbon dioxide and carbon monoxide generation (CDG) measurements.” (1165)
I really found that the detail and complexity of HRR very interesting this week. There certainly is a lot of math involved in determining the exact HHR, even more so when the material is unknown. I think this is a very important principal to understand when attacking a fire!
BITEAU, H. U. B. E. R. T., STEINHAUS, T. H. O. M. A. S., SCHEMEL, C. H. R. I. S. T. O. P. H. E. R., SIMEONI, A. L. B. E. R. T., MARLAIR, G. U. Y., BAL, N. I. C. O. L. A. S., & TORERO, J. O. S. E. L. (n.d.). Calculation Methods for the Heat Release Rate of Materials of Unknown Composition. Retrieved from https://apus.intelluslearning.com/lti/#/document/285759961/1/ce666714f46d62207473a19aad51c9c4/21dd175d7cb5163d0d42725461c4d649/browse_published_content/17930/98660/143365/5/lesson/lesson?hideClose=false&tagId=185491&external_course_id=402978&external_course_name=FSMT311 I001 Fall 19