Computational model of new clean-up technology

We have just published a paper in the journal Environmental Modelling & Software reporting our computational model of the combustion technology that cleans soils (EMS 2011, in press). Based on the physics of the problem, the model simulates the destruction of industrial chemicals found extensively polluting the subsurface and aquifers.

This very promising remediation technology is called STAR (Self-sustaining Treatment for Active Remediation) and was developed and patented at the University of Edinburgh. The BBC described it as "It burns away pollutants such as oil and petrochemicals from the ground, but leaves the original clean soil behind" [New clean-up technology trialled, 2010]. It consists on boring the site at a few strategic locations, and inserting at some depth a source of heat (igniter) and a source of oxidizer (air injector). The smouldering combustion front is initiated by the igniter, and the rate and location of the front is controlled by the injectors. Even compounds that are resistant to biodegradation are effectively destroyed by STAR. The latest pilot test was conducted at a former cresol manufacturing facility in New Jersey. It demonstrated the rapid rate of contaminant destruction and the high remediation efficiency (95 to 99.99%), with an measured sustained destruction rate up to 800 kg/day.

STAR relies on the principles of smouldering combustion of liquid fluids impregnated in porous media. Schematic from Siremlab.

The model is two dimensional (subsurface slices, vertical and horizontal) and combines a simulator of  airflow through the soil with calculations of the propagation of the smouldering combustion front. The propagation component  is based on a fire growth simulation, the same principle used in some wildland fire models like FARSITE. The model handles well the most challenging physical scenarios of heterogeneous soil composition and multiple contaminated spots (see second figure below). The results show that air permeability, which affects the movement of the injected air, is a dominant factor for the spread rate and shape of the combustion front.

Simulation with low permeability regions: (a) model domain set-up, (b) distribution of air (vector size range: 0.00–0.430 m/s) and position of the smoldering front 625 s (10.4 min) following ignition, (c) contour plot depicting the position of the smoldering front at 125 s (2.1 min) intervals from t = 0 s to 1500 s (25.0 min). (Figure 15 of the paper).

The model can now be used to optimize STAR and its deployment for specific contaminated sites. For example, to help finding the best location for injectors and igniters, or the most convenient distribution of multiple bore holes (eg, vertical, horizontal, staggered). 

Moreover, because the physical principles in the model are fundamental, it can be used to study other large-scale smouldering phenomena of importance like subsurface peat and coal fires.

STAR and smouldering combustion as a remediation concept are pending patent approval (UK Application 0525193.9 and PCT Application PCT/GB2006/004591, priority date December 2005). The full reference of the paper is:

S MacPhee, G Rein, J Gerhard, A Novel method for simulating smouldering propagation and its application to STAR (Self-sustaining Treatment for Active Remediation), Environmental Modelling & Software (in press), 2011. doi:10.1016/j.envsoft.2011.11.004 

Travelling fires paper wins Lloyd's Science of Risk Prize

Feb 2013 update: Read more about this work and how it ended up in a real building in this post.

We have won the 2011 Lloyd’s Science of Risk Prize in the Technology category for the paper "The Influence of Travelling Fires on a Concrete Frame" (published in Engineering Structures 33).

Winners of the 2011 Lloyd’s Science of Risk Prize. Dr Law is is second from the right.

The work argues that the trend towards open plan offices has changed the types of fire likely to occur in modern buildings. His paper uses science to look at ways to improve engineering guidelines and building design, reduce the risk of travelling fires, and help insurers better quantify and model fire risk. The work was founded by BRE Trust and Arup.

 Progression of the 2.5% and the 25% travelling fires across the floor plate (Fig 4 in the paper)

Temperature profiles for the average rebar in the final bay (Fig. 8. in the paper)

The Science of Risk Prize was launched by Lloyd’s in 2010 to stimulate cutting edge research into the latest emerging risks facing businesses.

For more details on the work, see here the paper (open access), a poster and related presentation.


NOTE: My team also won the 2010 Lloyd’s Science of Risk Prize in the same category with a paper on the modelling of tunnel fires. Two in a row :)

Smouldering mega-fires in the Earth system

I just gave the presentation "Smouldering mega-fires in the Earth system" at the conference Exploring the Mega-fire Reality, Florida State University. It went well very,  good questions (~8) from audience and great feedback. The abstract is below.

Smouldering mega-fires in the Earth system

Abstract
Smouldering fires, the slow, low-temperature, flameless burning of organic matter release anually at a global scale the equivalent to ~15% of man-made carbon emissions. It accounts for the accidental burning of fossil fuels, including natural as well as antropogenic causes. Very large fires of organic matter (mostly in peatlands) have burnt since past millennia for long periods of time (months, years, decades; the longest continuously fires on Earth). Flaming forest fires have been the central focus of most research, but smouldering mega-fires are paramount to the Earth System and have received very little attention. Smouldering is the most persistent type of combustion phenomena; the easiest to ignite, and the most difficult to suppress. Peat fires propagate slowly (~1 mm/min) through organic layers of the ground and can reach depth >5 m when large cracks or a natural piping system exists. It is a 3-dimensional phenomena, spreading deep into the soil and over extensive areas of land. The depth of burn is given by the location of the inert layer, very moist layer (>125%MC) or firefighting attempts. Observed depths of burn reported in the literature range from 0.1 to 5 m, with the average around 0.5 m (=75 kg/m2 of fuel consumption). This is 40 to 90 times larger than flaming fires. In terms of fuel consumption, these are mega-fires. This is of great concern given that world peatlands contain more terrestrial carbon than the forests or the atmosphere. Compared to the natural carbon flux to the atmospherefrom from peatland degradation, smouldering fires is 3,000 times faster. These wildfires burn fossil fuels and thus are a carbon-positive fire phenomenon via soil moisture deficit and self-heating. Warmer temperatures at high latitudes are resulting in more frequent Artic fires and unprecedented permafrost thaw.

Smouldering and self-sustaining reactions in solids: an experimental approach

I am delighted to announce that the PhD thesis of my student Rory is now online:

Smouldering and self-sustaining reactions in solids: an experimental approach (clik on title for pdf)
by Rory Hadden, PhD, University of Edinburgh, 2011 

The Ostedijk on 21st February (the 5th day) after
the hold was opened and before specialized firefighting activities had
commenced. Derived from photograph courtesy of Agencia EFE.

Abstract: Smouldering combustion governs the burning of many materials in the built and natural environments. Smouldering is flameless, heterogeneous combustion which occurs when oxygen reacts with the surface of a solid fuel. Understanding the conditions which will result in the ignition and smouldering of a porous fuel is important and the phenomena involved are complex and coupled, involving heat and mass transfer, and chemical kinetics. This thesis reports experimental studies of the ignition, spread, suppression and emissions from reactions in porous media. Similar experimental techniques are shown in this thesis to be applicable when studying a wide range of solids which undergo self-sustaining reactions. This thesis is presented in a manuscript style. Each chapter takes the form of an independent paper which has been prepared for journal publication and as such, each chapter can stand on its own as a piece of research. A final chapter summarizes the findings and conclusions and suggests further areas of research.

The evolution of char and peat fractions throughout the
experiment and the mass loss rate. The fraction of peat decreases and
the fraction of char increases from the beginning of the experiment until
around 20 min. During this period, the pyrolysis front is propagating
through the sample, resulting in the formation of char from the thermal
decomposition of peat. After 20 min, the pyrolysis front has propagated
through the sample and the resulting char is undergoing oxidation to
form ash and gaseous products. Error bars represent the average error
from three repeats.

Chapter 1 presents a study of self-sustaining decomposition (SSD) of NPK ammonium-nitrate-containing inorganic fertilizer. Findings were applied to the events that occurred aboard the Ostedijk in 2007.

Chapter 2 is a study of smoulder in polyurethane foam to study the relationship between sample size, critical heat flux and spread rate. This is important becuase smouldering fires are the leading cause of residential fire deaths in developed countries and polyurethane foam is ubiquitous in the modern world.

Chapter 3 presents an experimental investigation into the ignition of porous fuels by hot particles. This is related to the problem of spotting ember ignition in wildland fires which is a major, but poorly understood, spread mechanism. The process of spotting occurs in wildland fires when fire-lofted embers or hot particles land downwind, leading to ignition of new, discrete fires.

Chapter 4 is an investigation into the suppression of smouldering coal. Subsurface coal fires are a significant global problem with fires in China alone estimated to consume up to 200 million tons of coal per year. As global demand for coal increases, accidental fires are a waste of a useful energy resource as well as a source of pollution and greenhouse gases. The results are the first attempt reported in the literature to study the suppression of these fires under controlled laboratory conditions.

The mass flux of CO (red) and CO2 (blue) for experiments
in which flaming was ignited using a pilot flame (solid) and where
only smoulder was observed (dashed). The shaded region represents
the duration of the flaming. The inset details differences in emissions
during the period of flaming.

Chapter 5 presents an experimental investigation of the smouldering behaviour of peat. This is of particular interest in understanding the impact of smouldering fires on the earth system. The longer burn durations and different combustion dynamics of smouldering compared to flaming means that they have been shown to consume large amounts of biomass in, and contribute significantly to the emissions from, natural fires occurring in peatlands. The dynamics of smouldering peat in shallow, strong fronts was studied in the Fire Propagation Apparatus and a smoulder reaction framework with two burning regimes is presented.

Chapter 6 complements Chapter 5 with an analysis of the CO and CO2 emissions for smouldering and flaming peat. This data can be used with large-scale measurement techniques to improve emission estimates. The emissions are found to be dependent of the burning regime and the type of combustion with flaming resulting in higher fluxes of CO2 and lower fluxes of CO compared to peat smouldering. The large majority of emissions (85% of CO2 and 97% of CO) are released during the smoulder phase of the reaction. This highlights the differences in the chemical processes occurring under these two modes of combustion.

Chapter 7 summarizes the research undertaken in this thesis and presents possible further work.

Accidental combustion of a coal waste heap in Scotland burning since 2009

Researchers at the Universities of Edinburgh and Strathclyde have studied a burning Bing. A 30 m high waste heap at Bogside, North Lanarkshire, Scotland, started to smoulder (flameless combustion) in 2009, approximately 80 years after the closure of the pit.

 The work was presented at the Geological Society of America Annual Meeting in Minneapolis, USA. Presentation reference: Investigation of self-sustained combustion of a coal waste heap in Scotland. And it has featured in the The Scotsmant, Edinburgh website, Strathclyde website, and Vision Systems (on our use of thermal imaging).

Photo composition, clik to enlarge.

Coal mining was widespread in the central belt of Scotland from 1830 until the 1970’s and created a legacy of waste heaps or ‘bings’ that still dot the landscape. High content of coal fines and carbonaceous shales, make bings very prone to self-heating and smoldering combustion.

Chemical, geotechnical and physical parameters of the Bogside Bing have been studied. A combustion front is moving from west to east along the axis of the bing at an approximate rate of 1m/month. Three well-defined zones were identified and mapped using thermal imagery and temperature probes: the undisturbed zone, the preheating plus drying zone and the combustion zone. The subsurface fire results in a detrimental effect to the vegetation and structural integrity of the heap.

Spread of the combustion is accompanied by the development of vents ahead of the front, fissures that run parallel to the direction of heating and smaller landslips along the flanks. Changes to the heap's soil mechanics induced by the smouldering front create a network of fissures, some running deep, that supply the front with enough air to sustain the process.

Analysis of gas from the vents, show elevated CO2, CO, CH4 and SO2, and partially depleted in oxygen. All these are indicative of smouldering activity within the bing. The primary environmental concerns are likely to be from SO2 release and metals leaching from waste material (i.e. Pb, Se, Cr). The stability of the structure may be compromised as smouldering progresses. Bogside Bing continues to release products of combustion and represents an accidental source of fossil fuel burning.

Dr G Rein next to a water vapour vent on top of the Bogside Bing

Full reference of the presentation:
K Torrance, C Switzer, G Rein, R Hadden, C Belcher, R Carvel, Investigation of self-sustained combustion of a coal waste heap in Scotland, Paper No. 282-8, 2011 GSA Annual Meeting, Minneapolis 9–12 Oct. 2011.

Abysmal technical gaps in Scientific American

I recently sent a Letter to the Editor of Scientific American calling her attention to the abysmal technical gaps in the September issue article "Castles in the Air" by Mark Lamster where the failed prophecy that the attacks of 9/11 were to end the age of the skyscraper is discussed. The letter can be read here and is reproduced below. 


UPDATE Sept 2011: This letter was followed by two more from Dr Bisby and Hilditch
UPDATE Dec 2011: The letter of Dr Bisby has been published in the December 2011 issue of Scientific American. 


--

(email sent on Thur 15 Sep 2011 to editors@sciam.com) 

Dear Editor of Scientific American,

Your September issue included the piece "Castles in the Air" by Mark Lamster where the failed prophecy that the attacks of 9/11 were to end the age of the skyscraper is discussed.  The article highlights that 2011 will be the single greatest year for the construction of tall buildings in history. That China is leading the skyscraper boom, yet their engineering design is dominated by American firms.

The article discusses design issues on evacuation. But the World Trade Center was designed to evacuate rapidly, and so both towers WTC1 and 2 did below the impact floors on 9/11. WTC7 was also evacuated in time.

The article also discusses design issues on aircraft impact. But the World Trade Center was designed to withstand the impact of a large aircraft, and so both towers WTC1 and 2 did on 9/11. They collapsed because of fire. WTC7 was not hit by an aircraft, but collapsed due to fire as well.

The article goes to imply that the design of tall buildings for protection against terrorist attacks is mostly about aircraft impact and evacuation. It does not discuses fire. But WTC 1, 2 and 7 collapsed because of fire.

So they only issue that is not addressed in the article is the one that brought World Trade Center down, and the one where design advances over the past decade have been most marginal. This is a thin favour to fire engineering and to the safety of tall buildings.

Dr Guillermo Rein
Senior Lecturer in Mechanical Engineering
University of Edinburgh
http://www.eng.ed.ac.uk/~grein
"so easy it seemed, Once found, which yet unfounded most would have thought, Impossible!" J Milton 

Disasters of divine origin and Engineering

Yesterday, on the train from King's Cross to Waverly, I read in History Today an interesting article about the other Great Fire of Rome (AD 192), second after that with Nero's infamous role in AD 64:

Galen and the Great Fire of Rome

A newly rediscovered ancient letter by the great physician Galen offers a prime example of how fire was seen as a act of god against which humans could do little. These two excerpts serve as example:

"There was no massing of dark clouds, but a preliminary earth tremor was felt. There was no thunderstorm present when either a bolt of lightning struck, or a fire broke out as a result of the tremor. The entire Temple of Peace, the largest and most beautiful of all the buildings in the city, was burnt to the ground"

 "[Sudden weather changed to heavy rain] For this reason it was known that the disaster was indeed of divine origin. For people now believed that the fire was started, and stopped, by the will and power of the gods"

Unfortunately, this tradition permeated with time so deep into human culture that it is still possible to recognize it in many reactions to the fire problem. For example, see the recent reaction of the Governor of Texas who asked for praying to solve the extreme drought that now has led to extreme fire behaviour (Texan megafires). NOTE: I have nothing against praying. I pray some times, but not in profesional activities.

We teach better at engineering schools. The incoming generations of engineers are taught to solve the problems faced by society using the best tools available (eg, analitical skills, design, science, technology and creativity), and not to rely on divine intervention. In particular for fire safety engineers, they are taught to design to protect life and property against the detrimental effects of heat and smoke produced by accidental fires.

Accidental Burning of Fossil Fuels

(aka, Accidental Emissions from Fossil Fuels)
Next week, I will present at the Royal Academy of Engineering a brief poster summarizing the work that I have developed with the generous funding of the RAEng/Leverhulme Fellowship. The poster is here (pdf). A related seminar I gave at UC Berkeley in July can be watched in youtube here (and see at the end of this post). The following reproduces the content of the poster:

World energy use and climate change science have led to concerns on sustainability, man-made burning of fossil fuels, and carbon emissions. Most attention is paid to energy efficiency, clean technologies and new resources. But unintentional and non-anthropogenic sources contributing to the problem have been ignored. Smouldering megafires, the largest and the longest-burning fires on Earth (>6,000 years), take place in all continents except Antarctica, and burn fossil fuels accidentally.

Smouldering of carbonaceous media (flameless combustion) is the most persistent fire phenomenon on Earth. Photo by Jens Buurgaard Nielsen (wikipedia).

Very large smouldering fires of carbonaceous natural media (coal seams and peatlands) have burnt since past millennia for long periods of time (months, years, decades). Peat fires burn during the warm/dry season in Indonesia, Canada, Russia, and USA. Hundreds of coal fires continuously burn in USA, China and India. Globally, the problem has grown to a current carbon release equivalent to 10-30% of man-made emissions, and a coal consumption rate five times faster than that of Germany.

Oct 1997: aerosol imaging by NASA TOMS shows the vast smoke haze released by smouldering peat fires in Indonesia. Photo by NASA.

Smouldering phenomena involve the burning of fossil fuels and are carbon-positive. This creates a positive feedback mechanism in the climate system: Moisture deficit and self-heating of carbonaceous media are enhanced under warmer climates and lead to more frequent smouldering fires. Warmer temperatures at high latitudes are already resulting in large smouldering fires in the Arctic (e.g., Alaska 2010).

Positive feedback by smouldering fires in the climate system (topics I study are represented by red arrows)

Stopping these fires is an engineering task at the Earth-scale. RAEng states that “geoengineering provides options in which the Earth’s climate is deliberately manipulated to offset the effects of global warming due to increasing levels of greenhouse gases”. I am contributing to this through the study of the ignition, spread, emissions, and suppression of smouldering phenomena. I aim to develop both fundamental understanding and technological solutions to this problem.


Accidental Burning of Fossil Fuels (RAEng 2011)

Smouldering wildfire burning in New Orleans

The organic soil of Loiusiana marshes near New Orleans is smouldering in at least two separated locations. The fire continues to slowly spread after several days, and the smoke is now affecting town up to 160 km away. The Louisiana National Guard has been called in to help in the suppresion.

Smouldering fires of organic soils like peat burn underground and are the most difficult fire pheonmena on Earth to extingish. The top firefighter in Loiusiana said it better: "Once it’s underground, it’s next to impossible to fight. You can’t bring enough water to wet down that soil".

And note that the same article where the coment was made, report that the smouldering peat fires are still smouldering in the Great Dismal Swamp even after the arrival of hurricane Irene!

Cut or not cut peat? but never let it burn accidentally

Prof Ian Rotherham, ecologist and landscape historian at Sheffield Hallam University, has written a letter to The Telegraph "Peat cutting must be regulated, not banned". He argues for "enlightened management of peat resouces". The process of peatlands restoration must continue. But he notes that this could be combined with traditional uses as domestic fuel; "we can allow the traditional peat fire to glow gently in the cottage hearth as it has done for centuries".

The debate of protecting human heritage vs. protecting precious ecosytems is a valid one. And it must continue. But often, in fact by far most of the time, more attention is given to the delirebate burning of small quantities of peat for domestic use than to the accidental and unintended burning of peatlands. This are the largest and the longest burning fires on Earth. Some are biogenic. Examples are abundant (for example in UK, Russia, USA and Indonesia). These fires have been burning since past millennia for long periods of time (weeks or months), and consume large amounts of biomass. Smouldering fires consume 50 to 100 times more biomass per unit area than flaming wildfires. The global problem has grown to a current carbon release equivalent to 10-40% of man-made emissions.

Cut or not cut peat, I do not know, but never let it burn accidentally.

Quenching the Reactive Earth - talk given at UC Berkeley

Quenching the Reactive Earth - Accidental Burning of Fossil-Fuels and Geoengineering

I recently gave a research seminar at the Department of Mechanical Engineering at the University of California where I presented some of my research ideas. I start by summarizing my academic career to date and then proceed to talk about smouldering mega fires of natural coal and peat deposits. I have termed these "accidental burning of fossil-fuels".

Modelling of transient flows in tunnel fires

Our most recent paper on tunnel fires has just been published in the journal Computers and Fluids. The title is:

Multiscale Modelling of the Transient Flows from Fire and Ventilation in Long Tunnels

The paper applies a transient multiscale approach to model ventilation flows and fires in a long tunnel. It couples dynamically a Computational Fluid Dynamics solver with a simple 1D model, allowing for a more rational use of the computational resources without loss of accuracy.

Schematic of the multiscale model of the1.2 km tunnel from portal to portal and including 10 jet fans pairs. The CFD domain of the fire region contains temperature contours showing the fire plume.

After all the fundamentals of the coupling are discussed, the methodology is applied to study the unsteady flow interaction between a growing fire and a ramping-up ventilation system in a modern tunnel (7 m diameter, 1.2 km long). To the best of our knowledge, this is the first time than a growing fire and a growing ventilation are studied together. The results allow for simultaneous optimization of the ventilation and detection systems, and allows engineering answers to questions that could not be posed before by tunnel designers.

Longitudinal velocity field computed 180 s after fire ignition (60 s after ventilation activation) for three ventilation scenarios (3, 5 or 10 jet fan pairs respectively). Velocity values are expressed in m/s.

The work is a continuation of the collaboration between Politecnico di Torino and University of Edinburgh led by Dr Francesco Colella (the work is based on this 2010 thesis "Multiscale modelling of tunnel ventilation flows and fires").

NOTE: An earlier paper related to this received the 2010 Lloyd's Science of Risk Prize.

Despite the laws of thermodynamics that govern wildfires: NYT article

The NYT published last month a very interesting article on the use of computer modelling of wildfires to aid fire fighting decisions during the recent extreme fire behaviour suffered in Arizona, USA.

The full article is Fighting Wildfires With Computers and Intuition. Some excerpts that I found interesting are:
...

Fire behaviorists work alongside meteorologists, given that the weather, especially wind patterns, plays a pivotal role in how a wildfire grows. The topography is also important because fires burn differently depending on whether they are going up a steep slope, across a valley or through a developed area. Then there are what firefighters call the fuels, which are the vegetation and other materials that give fires energy as they move along.

...

The fires that Arizona has experienced, some surging forward faster than expected, are testing the mathematical models that behavior specialists use. Tom Zimmerman, a fire behavior expert at the National Interagency Fire Center for the United Forest Service in Boise, Idaho, said that the Wallow Fire had on occasion advanced more quickly than the models predicted. “We use each fire to verify the models and make them more accurate,” he said.

...

Despite learning the laws of thermodynamics that govern fires, behavior specialists say there is still plenty of unpredictability to each blaze, which requires them to draw on their long experience. Fires can produce their own weather patterns, for instance, which can then end up altering the course of the fires.

...

Smouldering mega fires are back in Russia: burning peat

Remember the Russian wildfires last summer that choked the city of Moscow and other regions? These were smouldering mega fires burning for several weeks and caused by the slow burning of dry peatlands. See here for an introduction to smouldering combustion.

Unfortunately, they are back this summer. Last week, they were several flaming fires burning in the region of Moscow. After flames were extinguished, the peat was seen to smoulder. Given the pollution, environmental and climate disaster that the smouldering mega fires brought last summer, the worry is that they might burn for months in 2011 as well. Given the extreme difficulty of suppressing smouldering fires when these have already grown out of proportions, the Fire Service is afraid that the fate might be in the hand of the rain.

In the meantime, Greenpeace reported about 20 peat fires in Russia.

PD: There are currently smouldering mega fire burning in North Carolina, Georgia and Indonesia.

Call for papers: Fire Technology special issue on WTC Collapse

Fire Technology, the journal of the National Fire Protection Association published by Springer, is preparing an issue on the 2001 fire and collapse of World Trade Center.

The purpose is to collect research, forensic and engineering output of the highest scholarly standards synthesized in the 10 years passed since the event.

Multidisciplinary and international contributions are especially encouraged. Topics of interests include: WTC 1, 2, 5 and 7, the crash, fires, structural response, collapse, forensic conclusions, experiments, modelling, Fire and Rescue intervention, human behaviour, building design, post-collapse fires and recovery, previous attacks on WTC and related subjects.

Submissions will be accepted until 11th Nov 2011 at: http://fire.edmgr.com (choose article type "World Trace Center") .

The call for papers flyer can do downloaded here. Please spread the word, we are looking for a wide range of high quality submissions.

For further information, contact the Associate Editor of this special issue: Dr Guillermo Rein, The University of Edinburgh.

A New York City fireman calls for 10 more rescue workers to make their way into the rubble of the World Trade Center. Photo form Wikipedia, United States Navy ID 010914-N-3995K-01

Smouldering mega fire in North Carolina Wildlife Refuge

A peat fire has been burning in North Carolina since May 4 inside the Alligator River National Wildlife Refuge. It is only 75% contain so far, and the higher summer temperatures are arriving fast. It could burn for several more months.

It is believed to had started with a lightning strike [ref]. A recent local article reports "crews pump millions of gallons of water on stubborn ground fire that is part of the larger Pains Bay fire"

This brings reminisces of the 2008 Evans Road fire in the Pocosin Lakes National Wildlife Refuge (NC, not far from Alligator River National Wildlife Refuge). The initial flaming fronts were controlled within days, but the smouldering fire burned for 6 more months and consumed the organic soil down to 1 m deep (see hanging tree in the 2008 photo). 16000 ha were destroyed (2 times the year average for North Carolina). More than 400 firefighters stopped this smouldering mega fire by flooding and excavating the peat. Estimated costs in suppression alone are near $20 million. It was also believed to had started with a lightning strike.

Note that as opposed to flaming fires of forest land that can regrow in 50 to 100 years, peat is a pre-fossil fuel (or ancient carbon as Andy Revkin labelled in his twit), it takes >10,000 year to form. Thus peat fires are a net source of carbon emissions and provide a positive feedback to climate change. This accidental fossil-fuel burning taking place now releases carbon that will not be recaptured by new peat until the year 12011. By then, the Earth climate system had plenty of time to response and lead to a possible global change. I discussed this a recent talk I gave at the last European Geoscience Union, see previous blog entry here and insert below. The title was "Climate Feedbacks on Smouldering Earth".

Climate Feedbacks on Smouldering Earth (talk at EGU Vienna 2011)

Bifurcations and Forecasting Scenarios - in CO2 emissions

I was quickly reading over a new paper on renewable energy policy [Krey and Clarke 2011], and realized that there is a visual link between global CO2 emission predictions and a bifurcation diagram.

The bigger plot below shows "Historic and projected global fossil and industrial CO2 emissions across all scenarios between 1900 and 2100",  Figure 1 in Krey and Clarke 2011. The red-frame insert is the bifurcation diagram of the the logistic equation taken from here.

 

From Wikipedia: bifurcation diagram shows the possible long-term values (equilibria/fixed points or periodic orbits) of a system as a function of a bifurcation parameter in the system. It is usual to represent stable solutions with a solid line and unstable solutions with a dotted line.

Granted that the link is more visual than fundamental, and requires an artistic licence of some degree. Note that the first bifurcation starts at the point separating historical values from projected (aka predicted) values. Thus, history is the stable solution, and forecasts are unstable solutions, the source of the uncertainty. This could hint towards a new topic for the application of NKS (New Kind of Science) approach and his reliance on cellular automata similar to the logistic equation to explain complex systems.

Inaugural Lecture on Multiscale Modelling of Tunnel Fires

Last Wednesday 1 June, I gave this Inaugural Lecture on Multiscale Modelling of Tunnel Fires at the I Fire Engineering Conference at Universidad Politecnica de Valencia.

The lecture is based on the PhD thesis of Francesco Colella (2010), my second PhD student.

Multiscale Modelling of Tunnel Fires

Abstract

Tunnels represent a key part of the world infrastructure with a role both in people and freight transport. Past events show that fire poses the most severe threat to safety in tunnels. Indeed in the past decades over four hundred people worldwide have died as a result of fires in road, rail and metro tunnels. In Europe alone, fires in tunnels have brought vital parts of the road network to a standstill and have cost the European economy billions of euros. Within this safety strategy, the ventilation system plays a crucial role because it takes charge of maintaining tenable conditions to allow safe evacuation and rescue procedures as well as fire fighting. Throughout most of a tunnel network the ventilation behaviour may be approximated with a simple 1D flow model. However, there are some important - but relatively small - regions of the tunnel that require CFD analysis. The multi-scale model is the ideal tool for such tunnel studies as it allows accurate flow field predictions in some locations, yet allows simplifications where highly detailed data are not required. It is shown that the accuracy of the multi-scale model is as high as the full CFD approach. The 100 times lower computational time is of great advantage because many ventilation scenarios can be explored and extensive sensitive parametric studies can be conducted.

Forecasting Fire Dynamics - IOP talk

Yesterday 23 May, I gave this invited talk on Forecasting Fire Dynamics at the Institute of Physics Combustion Group meeting on Combustion Modelling for Challenging Applications, University of Southampton.

It is based on the PhD thesis of Wolfram Jahn (2010), my very first PhD student.

Forecasting Fire Dynamics IOP May 2011

Abstract
The concept of fire forecast could lead to a paradigm shift in the response to fire emergencies, providing the Fire Service with essential information borne from the combination of sensor observations and computer modelling. Ideas are being borrowed from weather forecast and high performance computing so the technology is currently being developed. Many questions remain to be answered in the next decade but preliminary working models (zone model and CFD) based on an inverse problem approach are already proving predictions with positive lead times. This talk presents the problem framework and explores concepts and results developed to date.

Fundamentals of Combustion Processes, Springer 2011

Spinger has published a new book on combustion. It is based on the long-running undergraduate course at UC Berkeley ME140 Combustion Processes taught originally by Prof Carlos Fernandez-Pello (my former PhD supervisor):

Fundamentals of Combustion Processes 2011, Springer (Amazon $79.11)

The book is very accessible to engineering students interested in combustion but not advanced in their thermal science studies yet. There are few, or none, books for this introductory level. The accompanying dozen videos of laboratory demonstration act as a great illustration of each chapter content.
I am very familiar with the course and the labs, and I highly recommend the textbook for an introductory course. I was Teaching Assistant of this course for four semesters from 2002 to 2005. Such good memories, I loved it.

The park that came back from the dead

I was quoted in the article that The Independent published last Saturday on Spain's wetlands National Park Las Tablas de Daimiel:


The park that came back from the dead

The article quotes some of my comments published in the 2010 interview for El Pais. They said Guillermo Reim, but sure the meant Rein :).

The article summarizes the recent story of the park, from being completely dry due to 5-year drought, to the initiation of smouldering peat fires in summer of 2009, and then to sudden massive rain floods that arrived in early 2010. Now the Park is beautiful. See above a photo-comparison that I made; Nov 2009 vs. Aug 2010. But for how long will the park be flooded as is its natural state? No one knows for certain, and most politicians are not interested in the issue.

Wildfires UK and interviews in the BBC and LBC Radio

The unusual warn and sunny weather spell that we have been enjoying recently over most of the UK has unfortunately led to an intensification of wildfires.

Because of the sudden media attention on the topic, on 4 May I was interview by BBC Radio Wales about wildfire dynamics. You can listen to the audio here. Minutes after, I was interviewed by Nick Ferrari in LBC Radio (97.3).

The worst is about to come if the dry weather continues and the peat dries. Dry peat can ignite easily. Smouldering peat fires are the most devastating fires in the Earth system, and can be linked to climate change.

NOTE: This was the second time I talked to Nick Ferrari in LBC Radio. I talked to him on 19 April about the possible ignition sources of the scrapyard fire in London that led to closure of the M1 road.

Laser guns and Ignition times - research paper

We have published recently a paper in Combustion and Flame titled "Numerical Investigation of the Ignition Delay Time of a Translucent Solid at High Radiant Heat Fluxes"

This investigation revisits the theory explaining the ignition of a solid surface via a radiation external source. It led to a discovery affecting our understanding of how fires start and spread. The paper explains the failure of the classical ignition theory in polymers by using all the experimental data available to date and using a computer model to identify the missing mechanism causing the classical theory of ignition to fail when heat flux level are high. This mechanism is in-depth radiation, aka, the fact that many polymer materials are translucent to radiation.


This finding could help the US Navy fine tune their latest gadget. The BBC reports that they have fired a laser gun from one of its ships for the first time. They used a high-energy laser to carefully deliver a high flux of energy to the polymer surface covering the boat engines. This created a hot spot that reached ignition after some time, setting the engines on fire and disabling a boat. The ignition time can range from a few seconds to minutes, depending on the power of the laser. See the figure below extracted from the paper.

Time to ignition of black PMMA samples for a wide range of experimental conditions in the literature.

Our paper, and the model used in it, allows to calculate with higher precision the time required to reach ignition depending on the power of the laser and the material being heated. Higher precision calculating  the ignition time avoids failed attempts and reduces expensive laser time. It would lead to a more reliable and less costly weapon. The better tuned damage caused would be useful in non-lethal applications as well.

More at: N Bal and G Rein, Numerical Investigation of the Ignition Delay Time of a Translucent Solid at High Radiant Heat Fluxes, Combustion and Flame 158, pp. 1109–1116, 2011 http://dx.doi.org/10.1016/j.combustflame.2010.10.014

Oral presentation at EGU: Climate Feedbacks on Smouldering Earth

Yesterday 6 April, I gave this talk on Climate Feedbacks on Smouldering Earth at the 2011 European Geosciences Union, Vienna:

Climate Feedbacks on Smouldering Earth (talk at EGU Vienna 2011)

Abstract:

Climate Feedbacks on Smouldering Earth: Enhancement of Moisture deficit and self-heating of fossil and pre-fossil soils
 
Guillermo Rein
University of Edinburgh, School of Engineering, United Kingdom (G.Rein@ed.ac.uk)

Global smouldering phenomena, the slow, low-temperature, flameless burning of organic soils, is the most persistent type of combustion phenomena and the longest continuously fires on Earth (>6,000 years). It take place since deep times and in many ecosystems, special boreal and tropical ones. These are accidental sources of carbon emissions that during millennia have been slowly burning fuels with zero energy efficiency, consuming large amounts of fossil energy resources (coal seams), destroying natural ecosystems (peatlands) and emitting greenhouse gases and pollutants. The global problem has grown in the last decades to an estimated release varying between 10 to 40% of the man-made carbon emissions, and a coal consumption rate at least 5 times that of Germany. Because it involves the burning of fossil and pre-fossil fuels, this is a carbon-positive wildfire phenomena. This creates feedbacks in the climate system because moisture deficit and self-heating of organic soils
are enchanted under warmer climate scenarios and would lead to more frequent smouldering fires. Warmer temperatures at high latitudes are resulting already in more Artic fires and unprecedented permafrost thaw exposing large soil carbon pools to smouldering for the fist time since millennia.
While flaming fires have been a central focus in fire research, smouldering fires are as important in terms
of ecosystem damage, atmospheric emissions and socioeconomic threats but have received little attention. Moreover, these fires are difficult or impossible to detect with current remote sensing methods because the chemistry is significantly different, their thermal signature is much smaller, and the plume is much less buoyant.

Invited Talk in Madrid: Travelling Fires in Building Structural Design

Last Thursday 24th Feb, I gave this invited talk on Travelling Fires at the 6th International Congress on Performance-Based Design for Fire, Madrid:

G Rein, Travelling Fires in Building Structural Design, Madrid 2011

A related paper has just been accepted for publication:
A Law, M Gillie, J Stern-Gottfried, G Rein, JL Torero, The Influence of Travelling Fires on a Concrete Frame, Engineering Structures, (in press) 2011. doi:10.1016/j.engstruct.2011.01.034

Tunel Fire Modelling paper wins Lloyd's Science of Risk Prize

"A Novel Multiscale Methodology for Simulating Tunnel Ventilation Flows During Fires"

 published in Fire Technology 47 (1), pp. 221-253, 2011.

NOTE: See news article in physorg.com.


One of our papers won this year’s Lloyd’s Science of Risk Prize (Technology Category). The paper proposes a novel multiscale modelling approach generated by coupling a sophisticated three-dimensional computer model with a simple one-dimensional model. This allows for a more rational use of the computational resources. The methodology has been applied to a modern tunnel of 7 m diameter section and 1.2 km in length (similar layout to the Dartford Tunnels in London). More details here.

The prize is awarded to academics and "aims to keep the world’s leading specialist insurance market abreast of the latest academic knowledge and cutting-edge thinking".

NOTE: Our papers also were short-listed in Technology Risk and Climate Change Risk categories; "Forecasting Fire Growth using an Inverse Zone Modelling Approach" and "Increased fire activity at the Triassic/Jurassic boundary in Greenland due to climate-driven floral change" respectively.

Challenges in Computer Forecasting and Media- according to Dilbert