Sunday, 16 August 2015

PhD Studentship in Heat Transfer at Imperial College London

Applications are invited for a PhD studentship in the field of heat transfer and artificial intelligence funded by EPSRC and Arup.

2013 facade fire in Grozny. Photo from huffingtonpost
The research project, named INERSKIN, will develop a toolkit for fire safety optimisation of building façades. With a drive for thermally efficient buildings and sustainability, flammable insulation materials like polymers are more frequently introduced in the design of façades system. Because of the importance of façades and the increasing number of high rise buildings worldwide, it is critical that the interaction of materials and their performance in the event of a fire is understood, modelled and improved. INERSKIN will use artificial intelligence techniques and the state of the art of computational heat transfer to optimize their fire safety.

The student will join the Hazelab, the multidisciplinary research group led by Dr Guillermo Rein and part of the Thermofluids Division in the Department of Mechanical Engineering. The purpose of the group is to reduce the worldwide burden of accidental fires and protect people, their property, and the environment. To do so, Hazelab studies computationally and experimentally heat transfer processes, condensed-phase chemistry and thermodynamics of reactive solids.

You will be an enthusiastic and self-motivated person who meets the academic requirements for enrollment for the PhD degree at Imperial College London. You will have a degree in engineering or physics, and an inquiring and rigorous approach to research together with disciplined work habits. Interests in heat transfer and artificial intelligence are essential. Good team-working and communication skills are essential. Knowledge in fire science and building design are encouraged but not essential prior the project.

Candidates should fulfill the eligibility EPSRC criteria for stipend and fees (UK resident for at least 3 years). Please check your suitability at the following web site:

For further details of the post, contact Dr Guillermo Rein with up-to-date curriculum vitae.

Closing date: 30th September 2015.

Monday, 3 August 2015

Breakthrough in the understanding of flaming wildfires

I wrote a commentary article in the Proceedings of the US National Academy of Sciences (PNAS) about a recent stellar contribution to our understanding of how wildfires spread. In doing so, I have written in short the scientific context of wildland fires and also I put forward the possible impacts of the work on the field..
It can be read here ((10.1073/pnas.1512432112), and an except follows.

Breakthrough in the understanding of flaming wildfires

The rise of humanity was intimately bounded to fire. Humans first observed flames when fleeing wildland fires, the natural version of the phenomenon that would then become the most important technological achievement of the human race: the mastery of fire for cooking, lighting, settlement, hunting, and warfare (Bird 1995).
Wildfires are important to the natural sciences. Since deep time, the top surface of the Earth’s crust has been the interface where abundant plant organic matter meets an atmosphere rich in oxygen. This interface is flammable, especially in dry, windy and hot conditions, and leads to wildfire after an ignition event. Not only has fire contributed to shaping most ecosystems on Earth, but it plays essential roles supporting life through the regulation of atmospheric oxygen, the carbon cycle, and the climate (Bowmand et al. 2009, Watson et al. 1978).
As part of the current anthropogenic age, humans have also modified the fire regimes of many ecosystems, and have contributed for example to its cessation in certain regions (e.g., in the USA National Parks until 1960), or to increasing its frequency and severity through drainage (e.g., peatlands) and possibly through climate change (e.g., arctic fires). Of note, multiple US$ billions are spent annually across the world to fight wildfires for the protection of communities and valuable ecosystems.
Despite its central importance to the planet and to humanity, our understanding of fire remains very limited. For example, we currently cannot accurately forecast the location of a fire in 30 min time. To quote Hottel (1984): “A case can be made for fire being, next to the life processes, the most complex of phenomena to understand”. It comes as no surprise, then, that the discipline of fire science is less mature than other Earth science topics. For example, a quick look at the literature shows that there are three times more scientific studies published per year on volcanoes than on wildfires. Fire science requires more decades of fruitful research to mature and gain full understanding of this natural phenomenon.

Rate of Spread

The fate of a flaming wildfire starts with its genesis at ignition, by natural means like a lightning strike, or by anthropogenic means like slash-and-burn. Once ignited, part of the heat released by the flames will drive the spread over connected fuel beds of grass, shrubs, and trees. Another mechanism of propagation is by lofting burning embers that land farther away, but flame spread is more important. The dynamics of spread are such that wildfires accelerate with tail winds, dry weather, or up-slopes; and decelerate with head winds, rain or down-slopes.
The most lasting contribution to the science of wildland fires is the pioneering work of Rothermel in 1972 (Rothermel, 1972). He formulated an empirical model for predicting the spread rate of a wildfire. This formulation is ubiquitous and can be found at the core of most wildfire behaviour simulations. These simulations are currently in use by forestry agencies and firefighting command centres across the world. For example, Rothermel’s model is part of the US Wildland Fire Decision Support System, used in planning of every large and long duration federal wildland fire incident. However, Rothermel’s formulation is empirical: Whilst it can provide rough predictions of the rate of spread by calibration to previous laboratory data, it does not explain how fire spreads. Its empirical nature hinders scientific progress and does not allow for improvements to simulations. Until very recently, there was no valid scientific theory of wildfire spread that could complete Rothermel’s model.
Sketch of flame spread of a fire with tail wind over a fuel bed of fine particles. The paths for heat transfer by
radiation, convection, and flame contact are noted. According to Finney et al. (2015), the vortices are created by buoyant
instabilities and lead to ignition of the fuel by flame contact. Modified from Rothermel, 1972.

Finney et al. 2015

In this context, we see that the recent work of Finney et al. (2015) is a scientific breakthrough. Finney et al. have discovered the long-missing piece of the puzzle to understand wildfire dynamics. Their seminal work puts forward for the first time a fundamental, comprehensive and verifiable theory of flaming wildfire spread. Finney’s theory relates the rate of spread to basic fluid mechanics and heat transfer, and it is strongly supported by laboratory data and field observations across a wide range of scales from 10 cm to 15 m.

Let me put this in the framework of a simple theory. Fire dynamics dictate that spread can be seen as the succession of ignition events (Emmons 1963). This way, the rate of spread s of a fire is given in Eq. (1) by two terms, the length of fuel bed heated by the flames (expressed as δ) and the time that a fuel particle takes to ignite (expressed as tig) (Drysdale 2011).

 s=δ/tig   (Equation 1)

We know that mostly depends on flame inclination and the slope of the terrain, whereas depends mostly on fuel properties like particle size, moisture and plant composition. The scientific contributions of Finney et al. are cast around the novel identification of the two terms in Eq. 1 that govern wildfires.
First, by careful inspection of visual images of fire across scales, they show that vortex flows and peaks-and-troughs generated by the buoyancy of the flames are responsible for heating the fuel bed length δ. Then, temperature measurements then show that the intermittency of the peaks-and-troughs causes the flames to instantaneously touch the thin fuel particles, which in turn produces the contact ignition governing  tig. Figure 1 shows a sketch including these mechanisms.

Convection vs. Radiation

Their work feeds into a long-standing debate in the field on whether it is radiation or convection that controls the heat transfer to the fuel bed ahead (see Fig.1). The specific heat transfer mechanism affects the interpretation of experimental observations, and is critical in correctly formulating physically based models (Morvan 2011). Finney et al. settle the debate by identifying with strong evidence that heat transfer is controlled by flame contact, the phenomenon where both radiation and convection heat transfer are combined, but with the distinctiveness that the timing of flame contact is driven by convective flows.

Profound impact in fire science

Finney’s theory can have a profound impact in the field. The impact is four-fold regarding i) previous scientific studies, ii) wildfire simulations, iii) new technologies, and iv) multi-disciplinarity. These are explained in the following.
Previous scientific studies on wildfire spread should be revisited to help put Finney’s theory into a broader context. experimental and computational studies might need to be reinterpreted in the light of
the roles of flame intermittency and flame contact. The state of the art should naturally revisit and replace Rothermel’s model to give way to a new physically based Rothermel–Finney’s model.

Rothermel-Finney’s model would improve simulations of fire behaviour and help them gain in both accuracy and consistency. This in turn would allow the simulations to provide a more reliable layer of information during fire incidents.
The increased accuracy of simulations should eventually allow for high-fidelity forecasting technologies. A technology able to rapidly forecast the movement of a wildfire would lead to a paradigm shift in the response to emergencies, providing the Fire Service with essential information about the ongoing fire (Rios et al 2014).
The topic of wildfires is currently fragmented among the fields of biology, ecology, meteorology, chemistry, and combustion. These fields have a lot to offer one another, but better communication and cooperation are essential to move it forward. It is hoped that by strengthening the importance of fundamental knowledge and by settling long-standing debates, Finney et al. will serve as the basis for developing new multidisciplinary collaborations in the study of wildfires.

Finally, I foresee that after reading their work, many readers might start seeing the peaks-and-troughs reported by Finney et al. in every wildfire, as I already do now. As the English poet John Milton once said, “so easy it seem'd, once found, which yet unfound most would have thought impossible”.


  • MA Finney, JD Cohen, JM Forthofer, SS McAllister, MJ Gollner, DJ Gorham, K Saito, NK Akafuah, BA Adam, JD English (2015) The role of buoyant flame dynamics in wildfire spread. Proc. Natl. Acad. Sci. USA, 10.1073/pnas.1504498112.
  • MI Bird, Fire, prehistoric humanity, and the environment, Interdisciplinary Science Reviews 20(2), 141-154, 1995. DOI:10.1179/isr.1995.20.2.141A.
  • DMJS Bowman, JK Balch, P Artaxo, WJ Bond, JM Carlson, MA Cochrane, CM D’Antonio, RS DeFries, JC Doyle, SP Harrison, FH Johnston, JE Keeley, MA Krawchuk, CA Kull, JB Marston, MA Moritz, IC Prentice, CI Roos, AC Scott, TW Swetnam, GR van der Werf, SJ Pyne, Science 324 (5926), 481-484, 2009. DOI:10.1126/science.1163886. 
  • JE Watson, Lovelock, L Margulis, Methanogenesis, fires and the regulation of atmospheric oxygen, Biosystems 10 (4),pp 293-298,1978. 
  • HC Hottel, Stimulation of fire research in the United States after 1940, Combustion Science and Technology 39:1–10, 1984. doi:10.1080/00102208408923781.
  • RC Rothermel, A mathematical model for predicting fire spread in wildland fuels, USDA Forest Service, Intermountain Forest and Range Experiment Station, Ogden, Utah, Research Paper INT-115, 1972. 
  • HW Emmons, Fire in the forest, Fire Research Abstracts and Reviews 5, 163, 1963. 
  • D Drysdale, An introduction to fire dynamics, 3rd edition. John Wiley and Sons Ltd, Chichester, 2012. 
  • D Morvan, Physical Phenomena and Length Scales Governing the Behaviour of Wildfires: A Case for Physical Modelling, Fire Technology 47 (2), pp 437-460, 2011. doi:10.1007/s10694-010-0160-2. 
  • O Rios, W Jahn, G Rein, Forecasting wind-driven wildfires using an inverse modelling approach, Natural Hazards and Earth System Sciences 14, pp. 1491-1503, 2014. doi:10.5194/nhess-14-1491-2014

Monday, 27 July 2015

Improved travelling fires for structural design

The collapse of 1WTC, New York City, 10:28am Sept 11, 2001.
Photo by
9/11 Photos CC BY.
Our latest paper on travelling fires for structural design has been published in Structures (journal of IStrutE) with the title Improved formulation of travelling fires and application to concrete and steel structures.

Note: It is open access so you can read and share it without need for a subscription. We have posted in open access also our Matlab code to calculate the fire temperatures in zenodo.

Accidental fire can be disastrous, especially in buildings. The effect of fire on structural stability is critical in regard to safe evacuation and safe access for fire fighters, financial losses, and lost business. This is particularly the case in tall buildings where extended evacuation times are required due to phased evacuation practices. The World Trade Centre Tower fires in 2001 have highlighted the need of a more realistic design tools to represent fires in large compartments. 

Innovative architectural designs of modern buildings already provide a challenge to structural engineers. This is above all the case in structural fire engineering. However, most of the understanding and current design codes are based on the assumption of uniform fires in a compartment. In previous work, we have shown that fires in large, open-plan compartments, typical of modern architecture, travel from one part of it to another with non-uniform temperature distribution. These fires are referred to as travelling fires. And Travelling Fires Methodology (TFM) has been developed to account for the travelling nature of fires.

Illustration of a travelling fire and distribution of gas temperatures.
TFM was born in 2010 and offers a paradigm shift in the structural engineering of modern buildings. The concept has already been applied by engineering firms like Arup, BuroHappold or AECOM in the design of a dozen of iconic buildings in the UK (including the renovation of Battersea Power Station in London). TFM accounts for one of the fastest knowledge transfers from research to industry seen in fire protection engineering. TMF is now being studying in detailed in the USA for possible adoption as well.

The focus of this latest paper is on the improvement of the calculations of traveling fire (iTFM) to account for better fire dynamics, and the analysis of the effect on structural members. The proposed changes represent a simple yet powerful fire model. In particular, our paper shows that:
  • Using data from experiments and real fires, we limit the range of possible fire sizes thus reducing the time required for conduct TFM studies.
  • Analytical expressions are presented for generating time–temperature curves which are independent of grid size (previous versions of TFM) and can be easily calculated with any mathematical tool. 
  • Introduction of flapping term leads to reduced near-field temperatures for smaller fire sizes which cover a range between 800 and 1200 °C, as observed in real building fires. 
  • The location of the peak temperature in the compartment is found to occur at the end of the fire path (i.e. far half of the compartment from the ignition source).

Tuesday, 21 July 2015

Bosley explosions in wood mill

Last Friday evening, a crew of Sky News came home to interview me about the unfortunate explosions and fire in a wood mill in Bosley.You can watch the interview here.

Friday, 19 June 2015

Best Poster Award to reseach on the spread of peat fires

Congratulations to my PhD students from Imperial Hazelab Xinyan Huang and Francesco Restuccia for winning the Best Poster Award at the 2nd European Symposium on Fire Safety Science. Visiting student Michaela Gramola from University of Cambridge was also co-author. The work is an experimental study on how peat fires spread and lead to the largest fires on Earth.


Saturday, 30 May 2015

Research grant on travelling fires with Michigan

Egle Rackauskaite, PhD student
at the Imperial Hazelab.
I am delighted to announce that we have won a research grant from SFPE that will fund our summer collaboration with the group of Prof. Ann Jeffers at University of Michigan, Ann Arbor.

As we speak, my PhD student Egle Rackauskaite is at Ann Arbor working for the summer. She will use the SFPE Foundation Student Research Grant to continue the development of the pioneering design concept of 'travelling fires'.

Innovative architectural designs of new high rise structures already pose a challenge to engineers. This is above all the case in structural fire protection engineering. Understanding of fundamental mechanisms of whole building behaviour in fire has significantly increased in the last decades; however, most of this understanding is based on the assumption of uniform fires in a compartment. Recent work has shown that while the uniform fire assumption may be suitable for small enclosures, the large, open-plan compartments, typical of modern architecture, do not burn simultaneously throughout the whole enclosure. Instead, these fires tend to move across the floor plates as flames spread, burning over a limited area at any one time. These fires are referred to as travelling fires.

A travelling fire is a structural design concept that accounts for the spread of the flames along a large compartment. This creates two dynamic heating regimes to any structural element; the quick but intense heating by the direct impingement of the flames (near field), and the slow but limited heating by the smoke (far field).

Travelling fires challenge the design assumptions made in most design codes. Understanding the effects of travelling fires on structures is important for the development of modern cities with increased resilience to fire. Our work offers a paradigm shift in the structural engineering of modern buildings, and is directly impacting the way industry designs modern infrastructure and has already been applied to design a dozen iconic buildings in London, Manchester and Birmingham.

More information on travelling fires, see:

Thursday, 14 May 2015

Hazelab group photo

From left to right, in this group photo we have: Xinyan Huang (3rd year PhD student), Francesco Restuccia (1st year PhD student), Egle Rackauskaite (2nd year PhD student), Nicolas Ptak (intern), Virginia Alonso (postdoc) and Guillermo Rein (supervisor).
Unfortunately, two members were away from London on the day of the photo-shoot, Izabella Vermesi and Nils Roenner who were visiting their research sponsors in Boston and Ludwigshafen respectively.

Wednesday, 13 May 2015

Welcome Virginia to Imperial Hazelab

Dr Virginia Alonso has joined the Department of Mechanical Engineering at Imperial College London as postdoc in my research group, Imperial Hazelab.

Virginia is from Santander, beautiful city in the North of Spain. She graduated with an MSc in Physics and an PhD in Fire Evacuation Modelling at University of Cantabria, Spain, as member of the GIDAI group. She has also been a visiting scholar at the National Fire Protection Association (NFPA) and National Institute of Standard and Technology (NIST).

At Hazelab, she is involved in the project N-LAYERS to conduct a study and write a white paper where a holistic view of fire protection engineering is created, and the role of prevention is examined. Fire safety is made of a series of layers (e.g., prevention, fuel control, passive and active systems, evacuation, and structural response). All layers have a role in fire safety, but not all layers are equally important, effective or costly. In this project, Virginia aims to study in-depth the role of prevention in a systemic view of fire protection.

Tuesday, 21 April 2015

O-Revealer: Landmine clearance by the controlled use of fire

For the past few years, I have been developing a new method to clear landmine. Let me tell you a bit of the story.

More than 30 years after the 1982 Falkland War, only 5,000 landmines out of the original 25,000 anti-personal and anti-tank mines placed by the Argentine forces have been demined. Under the Ottawa Treaty on Anti-Personnel Mine Ban, the British government had the legal responsibility to remove them by 2009 but due the slow pace and expensive use of demining technologies, the government has asked for a 10-year extension. Because a large fraction of the documented 117 minefields in the Falklands are in peatlands, I have proposed a novel technology specific for locating landmines buried in peat using controlled combustion. I proposed this technology, which I have named O-Revealer, in a letter to the UK Ministry of Defense in 2007. They gently replied saying they was no interest from their part. But I endured nonetheless, and slowly continue working on the topic with the help of my engineering students.

Infrared image during our experiments
showing that O-Revealer exposes the whole body
of a non-metallic landmine (white dots added)
buried in peat at depth of 5 cm.

 Rationale of clearance by fire

O-Revealer has potential to be applied on hundreds of minefields across the world. In a preliminary search, far from being exhaustive, by crossing minefield maps and peat maps, we have found that peat and other histosols are known to host minefields not only in the Falklands but also in Vietnam, Burma, Laos, Uganda, Zimbabwe and the former Yugoslavia to name a few.

Peat is a soil with a large fraction of organic materials (also called histosol). This makes peat flammable.  When burning, peat fires are driven by smouldering combustion (not flaming combustion, which has a minor role). Smouldering is the slow, low-temperature, flameless burning of a porous fuel. Despite the existence of a body of literature on the ignition and spread of smouldering fires in peatlands, it has never been used before for demining. Smoldering fires can ignite and spread in soils up to a maximum moisture content (MC) around 150% (in dry base), and continuously burn for days, even weeks. Therefore, once smoldering fires are initiated in a minefield, especially during a dry season, it can consume the surface soil layer and expose mines which then can easy be identified and safely removed.

O-Revealer consists on a set of techniques to thoroughly control the fire by combining external means for ignition, ventilation, compartmentation and suppression. Not all histosol or weather conditions will be apt to this technology.  Local weather conditions are taken into account and adjusted for. By mastering the process, O-Revealer becomes an inexpensive and reliable technology, easy to deploy and that excels at the most important issues of humanitarian demining including detection of non-metallic mines, avoidance of false negatives, and  high demining rates.

We envision that O-Revealer will be applied in small plots of land, one at a time by each team, and following a strategy of combining it with other demining methods.

Proof of Concept

Exploded view of SB-33 dummy
landmine (diameter 85 mm)
We have conducted the very first laboratory experiments designed to study demining with fire on two different landmines, one plastic and one metalic. We selected 2 types of mines: the Italian SB-33 anti-personnel plastic landmine, and Serbian PROM-1 anti-personnel metal landmine. Their corresponding inert dummies were built with the same materials and at high-fidelity, and buried in peat with moisture contents ranging from very dry (MC of 5%) to normal conditions (MC of 130%). In all cases, the smouldering fire burn across the peat and left the dummy exposed to the open for easy identification and removal.

Two issues addressed

The spread rate of peat smoldering is on the order of 1 cm/h and the peak temperature is around 500 °C. This means that the soil, vegetation, landmines and other buried objects are exposed to a thermal pulse that sterilized the soil and may damage the mine (specially plastic ones) or even trigger a detonation of the secondary charge. So O-Revealer poses two additional issues that need addressing: the mitigation of the environmental impact on the soil ecosystem, and understanding when thermal triggering of the detonator might take place. From our experiments, we have learn that we can address these two issues at the same time by burning peat in a window of moisture content that allows for spread (MC<150 and="" but="" damage="" mine="" minimizes="" soil="" the="" to="">50%).

Sunday, 1 March 2015

Can poisonous Carbon Monoxide diffuse through building walls?

Fire Protection Research Foundation report: "Carbon Monoxide Diffusion through Porous Walls: A Critical Review of Literature and Incidents". Authors: Izabella Vermesi, Francesco Restuccia, Carlos Walker-Ravena and Guillermo Rein, Imperial College London
  It has been reported recently that in laboratory conditions carbon monoxide (CO) diffuses through gypsum board at a surprisingly high rate (Hampson, et al., JAMA 2013). Because CO is poisonous and a by-product of systems typically present in residential housing like boilers, generators, furnaces and automobile engines, this finding could have a significant impact on the life safety standards published by National Fire Protection Association (NFPA) and International Code Council (ICC), such as NFPA 101 Live Safety Code. For example, in USA, state legislation mandates the requirements for CO detection and warning equipment to be installed, but currently only enforces CO detection if there are communicating openings between the garage and occupied areas of a building.

Comparison between the experimental results for 0.5" gypsum wallboard
With the sponsorship of the Fire Protection Research Foundation, we have conducted a literature review on CO diffusion through walls that can be read here (open access). We have analyzed in detail the data from the recent experiments with a mass transfer model and confirm the validity of the findings for gypsum board. We have also found a number of actual incidents and laboratory experiments which confirmed the transport of CO through other types of porous walls. We also found studies on the transport of other hydrocarbon gases with larger molecules than CO that can also diffuse through porous walls.

Our analysis and review independently confirms that CO can diffuse through porous walls at a fast rate and that the phenomena may merit consideration in life safety standards.

Monday, 16 February 2015

Xinyan Huang wins Qatar Petroleum Medal for research on Clean Fossil Fuels

I am delighted t announce that my PhD student Xinyan Huang, working on peat fires, has been awarded the Qatar Petroleum Medal for PhD Research Excellence in Clean Fossil Fuels.
Xinyan (center) receives the QP Medal from Dr Naji Saad
during the award dinner at 170 Queens Gate.
Prof Blunt is to his left.

Xinyan wearing the QP Medal and the happy supervisor.

 The Press Release from Imperial reads:  

The Qatar Petroleum Medal and Prize for Research Excellence in Clean Fossil Fuels is awarded annually to a PhD student at Imperial College London who is in their third or fourth year of study. Sponsored by Qatar Petroleum, through the Qatar Carbonates and Carbon Storage Research Centre (QCCSRC), the award is to recognise their outstanding achievements in the field of Clean Fossil Fuels.

This year’s prize of £1000 and a commemorative medal has been awarded to Xinyan Huang from the Department of Mechanical Engineering. In a field of very strong candidates, it was his achievements in research and his publication record that impressed the judges. “Xinyan has been a fantastic student since he started here in 2012, it is a joy to work with someone like him who can seamlessly combine experiments and modelling to answer scientific questions” says Dr Guillermo Rein (that is me!), Xinyan’s PhD supervisor “I think this award recognises that he has been a valuable member of the engineering community both here at Imperial but also in the wider Clean Fossil Fuels field.” Xinyan’s thesis is a computational and experimental study of the chemical, heat and mass transfer mechanisms governing the smouldering combustion of peat. His research focuses on peat, which is essentially a young coal, and is providing a fundamental understanding of the accidental burning of this sub-fossil fuel. These are the largest fires on Earth with a massive carbon footprint. He has written numerous significant peer-reviewed papers and presented his work at conferences and seminars in the UK, Europe and further afield. 

“Xinyan’s work has brought new insight and quantitative modelling to an important, but to date under-studied, source of carbon emissions, peat combustion,” says Professor Geoff Maitland, Founding Director of QCCSRC “He joins a list of previous winners who have gone on to successful careers in industry and academia and we will wish Xinyan well in his future endeavours.” 

As well as conducting his research, Xinyan is a Teaching Assistant at Imperial and has been a Visiting Scholar at University of Science and Technology in China and at the National University of Singapore. The Qatar Petroleum Medal and Prize was awarded to Xinyan at the dinner during the QCCSRC Annual Review. QCCSRC is based within the Department of Chemical Engineering and the Department of Earth Science and Engineering.

Tuesday, 3 February 2015

Wildfires and the burnig of Pine needles

In our recent paper published in Fire and Materials, we use laboratory experiments to investigate the differences in fire dynamics between live and dead pine needles. This is important because limited research has been conducted on the burning characteristics of live fuels, which are commonly assumed to behave like moist dead fuels.

The high flammability of conifer forests in the Mediterranean and Boreal biomes is due mostly to the presence of needles in very large amounts. Needles are fine fuels that ignite and spread flames faster than coarse woody fuels and represent an important portion of the total fuel consumption in wildfires. Needles are found both in the tree canopies and on the ground. Live needles (green colour) are part of the foliage and typically burn in crown fires. Dead pine needles (red colour) are on the ground, accumulating gradually on the litter and humus layers, and burn both in surface and ground fires.

Samples of Pinus halepensis needles used in the experiments (from left to right): live, aged and dead.

Our fire calorimetry results show good repeatability and demonstrate that the difference in burning dynamics of live and dead pine needles is significant and can be quantified and understood. Using a series of 10 flammability parameters extracted from the experiments, we show that the most flammable samples are fresh dead needles, followed by dry dead and dry live needles. The least flammable is fresh live needles. Live needles ignite about four times slower, and burn with ~60% lower power and ~50% lower heat of combustion than dead needles. The results confirm the importance of moisture content in the burning behaviour of pine needles, but the differences between live and dead samples cannot be explained solely in terms of moisture but require consideration of plant chemistry and sample drying.

(Left) Time to ignition and (Right) flaming time.

The results show that there are fundamental differences in the physics and chemistry of the flames of these fuels and that fire dynamics does not follow a simple trend from live to aged and to dead fuels.

Our results also defy the common assumption that oven drying only affects the water content of samples, or that the drying conditions are not important. Data suggest that observed fire behavior is substantially affected by the drying process in the oven, which induces chemical and structural changes (eg, loss of volatile organic compounds inside the oven). The fact that oven drying is widely used in wildfire laboratory studies merits more research.

- F Jervis, G Rein, Experimental study on the burning behavior of Pinus halepensis needles using small-scale fire calorimetry of live, aged and dead samples, Fire and Materials (in press) 2015.  (open access)

Thursday, 22 January 2015

Doubt cast on global firestorm generated by dino-killing asteroid

Pioneering new research published in the Journal of the Geological Society.has debunked the theory that the asteroid that is thought to have led to the extinction of dinosaurs also caused vast global firestorms that ravaged planet Earth.

A team of researchers from the University of Exeter, Imperial College London, Planetary Science Institute and University of Vienna recreated the immense energy released from an extra-terrestrial collision with Earth that occurred around the time that dinosaurs became extinct. They found that the intense but short-lived heat near the impact site could not have ignited live plants, challenging the idea that the impact led to global firestorms.

These firestorms have previously been considered a major contender in the puzzle to find out what caused the mass extinction of life on Earth 65 million years ago.
The researchers found that close to the impact site, a 200 km wide crater in Mexico, the heat pulse - that would have lasted for less than a minute - was too short to ignite live plant material. However they discovered that the effects of the impact would have been felt as far away as New Zealand where the heat would have been less intense but longer lasting - heating the ground for about seven minutes - long enough to ignite live plant matter.

The experiments were carried out in the laboratory and showed that dry plant matter could ignite, but live plants including green pine branches, typically do not.

Dr Claire Belcher from the University of Exeter said: “By combining computer simulations of the impact with methods from engineering we have been able to recreate the enormous heat of the impact in the laboratory. This has shown us that the heat was more likely to severely affect ecosystems a long distance away, such that forests in New Zealand would have had more chance of suffering major wildfires than forests in North America that were close to the impact.  This flips our understanding of the effects of the impact on its head and means that palaeontologists may need to look for new clues from fossils found a long way from the impact to better understand the mass extinction event.”
Plants and animals are generally resistant to localised fire events - animals can hide or hibernate and plants can re-colonise from other areas, implying that wildfires are unlikely to be directly capable of leading to the extinctions. If however some animal communities, particularly large animals, were unable to shelter from the heat, they may have suffered serious losses. It is unclear whether these would have been sufficient to lead to the extinction of species.

Dr Rory Hadden, who was part of Dr Guillermo Rein's group in Imperial College by the time of the research and now is at the University of Edinburgh, said: “This is a truly exciting piece of inter-disciplinary research. By working together engineers and geoscientists have tackled a complex, long-standing problem in a novel way. This has allowed a step forward in the debate surrounding the end Cretaceous impact and will help geoscientists interpret the fossil record and evaluate potential future impacts. In addition, the methods we developed in the laboratory for this research have driven new developments in our current understanding of how materials behave in fires particularly at the wildland-urban-interface, meaning that we have been able to answer questions relating to both ancient mass extinctions at the same time as developing understanding of the impact of wildfires in urban areas today.”

The research was supported by a European Research Council Starter Grant, a Marie Curie Career Integration Grant, the Leverhulme Trust, the EPSRC and the Austrian Science Fund

Tuesday, 20 January 2015

Research Associate position on fire protection engineering in Imperial College London

Research Associate in the Thermofluids Division at the Department of Mechanical Engineering, Imperial College London.

Maximum salary on appointment will be £33,410 per annum*
*Candidates who have not yet been officially awarded their PhD will be appointed as Research Assistants within the salary range £29,350 - £32,520 per annum.

Fixed-term appointment available for up to 8 months in the first instance.

The Thermofluids Division wishes to appoint a Research Associate to conduct research into systemic fire protection engineering at Imperial College London.

The Hazelab is the multidisciplinary research group led by Dr Guillermo Rein and part of the Thermofluids Division in the Department of Mechanical Engineering. The purpose of the group is to reduce the worldwide burden of accidental fires and protect people, their property, and the environment. To do so, Hazelab studies computationally and experimentally heat transfer processes, condensed-phase chemistry and thermodynamics of reactive solids.

The Research Associate under the supervision of Dr Rein, will be involved in the project N-LAYERS to conduct a study and write a white paper where a holistic view of fire protection engineering is created and the role of prevention is examined. Fire safety is made of a series of layers (e.g., prevention, fuel control, passive and active systems, evacuation, and structural response). All layers have a role in fire safety, but not all layers are equally important, effective or costly. In this context, N-LAYERS wants study in-depth the role of prevention in a systemic view of fire protection.

The Associate would be in charge of conducting the multidisciplinary literature review on systemic thinking, resilience and layers of fire protection; construction of a novel framework for the white paper based systemic thinking; communicate with collaborators; and write the white paper.

A PhD (or equivalent experience and/or qualifications) or near completion of a PhD* in an area pertinent to the research subject e.g. Fire Protection Engineering, Mechanical Engineering or Chemical Engineering is essential.  In addition some background in fire dynamics and risk is also essential. High quality writing in technical English is desirable.

Informal e-mail enquiries may be made to Dr Guillermo Rein at or +44(0) 20 7594 7036.

Committed to equality and valuing diversity.  We are also an Athena SWAN Silver Award winner, a Stonewall Diversity Champion, a Two Ticks Employer and are working in partnership with GIRES to promote respect for trans people.
Closing Date:  20 February 2015 (midnight GMT)
How To Apply:                  
Our preferred method of application is online via our website.  Visit at or go to (Select “Job Search” then enter the job title or vacancy reference number into “Keywords”). Please complete and upload an application form as directed quoting reference number EN201500023SF, you must submit an application form for our posts along with a CV, if you do not fill in an application form, you will not be considered.

Alternatively, if you are unable to apply online, please email Ms Claire Soulal, Academic Administrator at: to request an application form.

Wednesday, 7 January 2015

Peat fires - a legacy of carbon up in smoke

Press Release:

It reads like a movie script – ash falling from the sky, thick smoke shutting down airports and businesses, road closures trapping remote northern villages. But this is not from a script; rather, it is a new study of what could happen through peat burning.

In an international paper released in the January edition of the journal Nature Geoscience, the researchers, led by University of Guelph professor Merritt Turetsky, focus on fires that burn through thick layers of peat (dead plant debris) that blanket the ground in ecosystems ranging from the tropics to the arctic.

Peat is a legacy of plant activity – plants acquiring carbon from the atmosphere to build their biomass. Those plants die and are incorporated into the soil. When those soils are too wet to support high levels of decomposition, those plant remains pile up over time.

"When people picture a forest fire, they probably think of flames licking up into tree tops, and animals trying to escape," said Turetsky. "But peat fires tend to be creeping ground fires. They can burn for days and weeks, even under relatively wet conditions. They lack the drama of flames, but they produce a lot of smoke." That smoke makes peat fires dangerous to human health. It can worsen air quality and even trigger asthma and other respiratory problems. "We know fires serve as a major source of human mortality globally," said Turetsky. "We are starting to understand that peat fires cause some of the most extreme air quality issues, but in general they are poorly understood." Turetsky and Brian Benscoter teamed up with fire scientists to summarize what is known about peat fires, from massive lightning-ignited fires that burn large areas of the boreal region to tropical fires often triggered by human activity.

"The tropical peatlands in Southeast Asia are a clear demonstration of how human activity can alter the natural relationships between ecosystems and fire," said Susan Page, a University of Leicester professor and co-author on this study. "Tropical peatlands are highly resistant to natural fires, but in recent decades, humans have drained peatlands for plantation agriculture. People cause the deep layers of peat to dry out, and also greatly increase the number of fire ignitions. It's a double threat." This causes a host of problems, including health issues, airport and school closures, and political tensions. The paper concludes that almost all peat-rich regions will become more susceptible to drying and burning with a changing climate.

“Thanks to satellite data, we are fully aware of the vast scale of burning in drained peatlands, mostly in Indonesia,” said co-author Guido van der Werf, a professor at Amsterdam’s VU University and and co-author on this study. “The scary thing is future climate change may actually do the same thing: dry out peatlands. If peatlands become more vulnerable to fire worldwide, this will exacerbate climate change in an unending loop." Peatlands store a large amount of carbon due to thousands of years of plant activity. When peat burns, carbon is released into the atmosphere.

 “Smouldering peat fires already are the largest fires on Earth in terms of their carbon footprint,” said Dr Guillermo Rein from Imperial College London, and and co-author on this study.

Peat fires and their effects will only increase as more towns are built and more resources developed near peat-rich regions, said Turetsky. “These types of fires have different impacts on ecosystems, and traditional fire management techniques will not be effective in combating peat fires. We need new tools to deal with these issues,” she said. The study is titled “Global vulnerability of peatlands to fire and carbon loss.”

Contacts: Guillermo Rein, Imperial College g.rein at

Friday, 26 December 2014

Peat fires and carbon loss

Together with co-authors in Canada, US, UK and Netherlands, we have just published a progress article in Nature Geoscience  (vol 8, 2014) on the carbon losses from peat fires: Global vulnerability of peatlands to fire and carbon loss.

Ssmouldering combustion of dry peat.Available at Imaggeo.
In the paper we review how fire is a threat to the naturally stored carbon in peatlands and has the potential to drastically disturb the carbon stocks. While dry peat is a very flammable substance because it is a porous and carbon-rich, the amount of carbon stored in peatlands exceeds that stored in vegetation globally. Peat fires are dominated by smouldering combustion, which is ignited more readily than flaming combustion but is more difficult to suppress. In fact smouldering fires can persist deeper and in much wetter conditions than flaming fires. In very wet or flooded peatlands, most of the carbon stock typically is protected from smouldering, and resistance to fire has led to a build-up of peat carbon storage in boreal and tropical regions over long timescales. But drying as a result of climate and human activity (eg, drainage) lowers the water table and increases the frequency, depth and extent of peat fires. The combustion of deep peat affects older soil carbon that has not been part of the carbon cycle for centuries to millennia, and thus dictates how fire emissions affect the carbon cycle and feedbacks to the climate.