Battery Electric Vehicles (BEV) fire simulation

[Adrian Halim]

Hi,

Is it correct that at the moment there are no ventilation simulation software that are capable to simulate Battery Electric Vehicle fires due to the lack of input data? I know that NIOSH is currently doing a research on mine vehicles' Li-ion battery fire, but to my knowledge research on full scale BEV fire (similar to the one done by Rickard Hansen and Haukur Ingason on UG mine diesel vehicles) is yet to be proposed.

 

[Kingsley Hortin]

Hi Adrian,

Whilst not an answer to your query, the below link is applicable to the potential for such incidents.

https://www.northernontariobusiness.com/industry-news/mining/underground-electric-vehicle-fire-provides-teaching-moment-for-sudbury-miner-3282728

[Craig Stewart]

The following advice is a preliminary research paper investigation.  Users considering lithium battery fires should undertake their own review.

BEV fires are exothermic chemical fires that can be described in terms of heat release rates (HRR) like any other type of fire.  They also release asphyxiant gases such as carbon monoxide like hydrocarbon fires although other gases may be more toxic.  As such, there is no reason that they cannot be modelled in fire simulation providing an estimate of the HRR can be made, however some considerations are needed, and more industry test work and validation would be welcome.  Also, remember a lithium battery fire can still spread to other more conventional fire fuel sources on the BEV such as tires, hydraulic hoses and oil etc which are still likely to be a greater hazard (by mass and heat) than the lithium battery itself.

If you are using VentFIRE in Ventsim, the HRR is sourced from the heat of combustion (per kg) and the gases are sourced from the yield rates of the combustible material.  For a lithium fire, the electrolyte chemistry and associated reactions are the main source of energy (which will change depending on the state of charge SOC), so a determination of the mass of the battery would have to be made by examining the likely HRR release rate versus the battery size.  Lithium batteries typically only have around 10%-15% of the runaway heat compared to diesel fuel by mass, hence the heat of combustion is much smaller, however the batteries carried by most BEV's tend to be much heavier than an equivalent fuel machine.

The heat release rate curve HRR is not dissimilar to a hydrocarbon fire - check literature and examples on the web for this.  While not a lot of test work has been done on underground machines it should provide some insight into how long a fire could burn for.  https://www.nature.com/articles/s41598-017-09784-z

The release of gases;  whilst CO gases are an asphyxiant , it is more likely that the fluoride gases released from battery fires will be more dangerous.  Studies indicate HF (hydrogen fluoride) could be emitted at a yield of up to 1kg per 30kg of lithium battery mass (for a fully charge battery - less otherwise).  Also important is that lithium battery fires don't consume large amounts of oxygen and may not be significantly impacted by low or no airflow, so set the oxygen yield consumption rate low in VentFIRE.   While Ventsim VentFIRE does not currently have a specific fire gas for HF, one of the other unused fire gases (such as NH3 or CH4) could be used to supplant and simulate this at a substitute yield rate. 

Exposure of humans to HF gas is poorly researched, however the CDC states exposure to 50ppm for 30-60 minutes may be fatal.  Short term (1 hour) exposure limits are recommended <8ppm

[Leo.Fan]

You get a nice question.

I think you can find the answer on battery-test-chamber