Dionysios I. Kolaitis

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• Ph.D. Mechanical Engineering
• Professor (Assistant) at National Technical University of Athens

The fire extinguishing performance, in a simulation with field experiment of wildland fire, of liquid BONPET and pure water was studied. The results show that 6% BONPET liquid has better performance than pure water. The fire extinguishing simulation shows that the extinguishing performance of liquid BONPET 6% reduces the temperature at the burning...

The residential sector is responsible for the largest share of global energy consumption, while the existing building stock in Europe is relatively old. This issue, in combination with the low rate of new constructions, highlights the necessity for deep renovation of existing buildings to reach NZEB standards. At the same time, in the last decades,...

Wildland fire rate of spread prediction models are important tools for the effective coordination of resident evacuation and fire suppression efforts. A comparative assessment of ten empirical and semi-empirical rate of spread prediction models is performed, using a selection of 203 laboratory experiments of surface spreading fires; special emphasi...

O período entre 2018 e 2022 mostrou-nos que o problema dos incêndios à escala global não está a diminuir, antes pelo contrário. Parece que as consequências das alterações climáticas já estão a afectar a ocorrência de incêndios florestais em várias partes do Mundo, de uma forma que só esperaríamos que acontecesse vários anos mais tarde. Em muitos pa...

O período entre 2018 e 2022 mostrou-nos que o problema dos incêndios à escala global não está a diminuir, antes pelo contrário. Parece que as consequências das alterações climáticas já estão a afectar a ocorrência de incêndios florestais em várias partes do Mundo, de uma forma que só esperaríamos que acontecesse vários anos mais tarde. Em muitos pa...

During a fire event, ventilated facade systems may contribute to external fire spreading to the upper floors of a building via the facade, thus representing a significant risk. In this frame, the performance of a typical ventilated façade system under fire conditions is experimentally investigated, using a full‐scale compartment‐facade test rig. Tw...

The effect of the vertical position of horizontal projections on the thermal and flow characteristics of Externally Venting Flames (EVF) was investigated by using a ¼ scale compartment-façade experimental setup to perform five fire tests. A constant 144 kW fire power level was set in all fire tests; the fire source was a methane-fed porous burner,...

Cross-laminated timber (CLT) is an innovative wood product that is increasingly used in both residential and non-residential construction projects, since it offers a range of advantages, such as light carbon footprint, quick erection time, good thermal and sound insulation characteristics. CLT members have the potential to provide excellent fire re...

Understanding of the physics and mechanisms of fire development and Externally Venting Flames (EVF) in corridor-like enclosures is fundamental to studying fire spread to adjacent floors in high-rise buildings. The main scope of this study is to investigate the burning behaviour of a liquid fuel pool fire in a corridorlike enclosure, to identify the...

This study investigates numerically the burning behaviour of a liquid pool fire in a medium-scale corridor-like enclosure in order to identify the key factors influencing External Venting Flames (EVF) characteristics as well as heat impact of the EVF on façades. Simulations were performed for four doorlike openings with the fire located either at t...

This study aims to numerically investigate the fundamental physical phenomena governing fire development and transition to Externally Venting Flames (EVF) of liquid pool fires in compartment façade configurations. Experiments previously performed using a ¼ scale ISO9705 room with an extended façade is simulated using Fire Dynamics Simulator (FDS)....

This work aims to investigate the fire development of a liquid pool in a corridor and externally venting flames (EVF) aiming to contribute to fundamental fire research towards ensuring fire safety of high-rise buildings. This study aims at experimentally and numerically investigate, with the use of FDS, EVF development in corridor-like geometries t...

Understanding of the physics and mechanisms of fire development and Externally Venting Flames (EVF) in corridor-like enclosures is fundamental to studying fire spread to adjacent floors in high-rise buildings. The main scope of this study is to investigate the burning behaviour of a liquid fuel pool fire in a corridor-like enclosure, to identify th...

Understanding of the physics and mechanisms of fire development and Externally Venting Flames (EVF) in corridor-like enclosures is fundamental to studying fire spread to adjacent floors in high-rise buildings. The main scope of this study is to investigate the burning behaviour of a liquid fuel pool fire in a corridorlike enclosure, to identify the...

Foreword This document is focused on problematic of firefighting in bio‐based buildings. It collects experience, information, knowledge and results from experiments which can be seen as helpful for firefighters to better understand structural fires with bio‐based materials and as well as for incident commanders with decision makings. As every fire...

In a building fire, the initial fire compartment is rarely airtight, since it is quite common for some opening (e.g. door, window) to be present, either by chance (e.g. a window left open) or due to the failure of the glazing in a high temperature environment. The opening provides essentially a physical connection of the fire compartment to either...

An accident in petrochemical industry can cause serious damages to human and animal health, property, environment and economy. That was proved by many accidents in the past. National laws, regulations, national, European or international standards or accepted protection principles define minimal requirements for safety and security protection of te...

To increase the gain from costly fire experiments and to facilitate engineering calculations of material performance in case of fire, there is an essential need for careful experimental design and proper characterization of material fire properties. In light of this necessity, the ASTM E1591 standard guide [1] provides a compilation of key material...

In the present study, a fully coupled thermo-mechanical simulation methodology is presented, capable of estimating the response of cold-formed steel drywall systems exposed to fire and evaluating whether or not compliance with the performance-based fire safety requirements is achieved, in terms of the load-bearing capacity (R), integrity (E) and in...

A number of recent high-profile fire incidents has clearly demonstrated that façade fires in high-rise buildings may have devastating effects, incurring significant life and property losses. The ever-stricter requirements for reducing building energy consumption have resulted in an increasing trend of installing combustible thermal insulation mater...

In a compartment fire, Externally Venting Flames (EVF) may significantly increase the risk of fire spreading to adjacent floors or buildings, especially when combustible insulation materials are installed on the building façade. An increasing number of recent reports suggest that existing fire engineering design methodologies cannot describe with s...

Gypsum “dehydration” phenomena, occurring when gypsum plasterboard wall assemblies are exposed to a high temperature environment, result in water vapour production and subsequent dispersion in the fire compartment; these phenomena are often neglected in relevant Computational Fluid Dynamics (CFD) simulations. Aiming to investigate the impact of gyp...

The current research activities of the Fire Engineering Unit (FEU) of the Heterogeneous Mixtures and Combustion Systems (HMCS) laboratory include the experimental and computational investigation of fire dynamics, fire spreading in buildings and façade systems, high-temperature behaviour of conventional and innovative building products and solid rea...

The Ventilated Façade (VF) system is a double-wall construction, comprising an external lightweight cladding panel and the building's façade, separated by an air gap; this system is used to increase the indoor comfort level (e.g. temperature, humidity) in buildings. Literature reports on VF systems focus mainly on investigating their behaviour in t...

In a fully developed under-ventilated compartment fire, flames may spill out of external openings (e.g. windows); Externally Venting Flames (EVF) pose a significant risk of fire spreading to adjacent floors or buildings. The main aim of this work is to comparatively assess a range of fire engineering design correlations used to describe the externa...

The ventilated façade (VF) system is a double-wall construction, comprising an external lightweight cladding panel and the building's existing façade, which is used to increase indoor comfort levels (e.g. temperature, humidity) in buildings. During a fire event, VF systems may contribute to fire spreading on the facade, representing a significant r...

The structural fire behavior of typical load-bearing drywall systems, consisting of light cold-formed steel (CFS) studs, sheathed with single or double layers of gypsum plasterboards and air cavity or mineral wool insulation, is investigated. For that purpose, an efficient numerical modeling approach with satisfying accuracy is developed and valida...

Externally venting flames (EVF) may emerge through openings in fully developed under-ventilated compartment fires, significantly increasing the risk of fire spreading to higher floors or adjacent buildings. Several fire engineering correlations have been developed, aiming to describe the main characteristics of EVF that affect the fire safety desig...

In a compartment fire, Externally Venting Flames (EVF) may significantly increase the risk of fire spreading to adjacent floors or buildings; EVF-induced risks are constantly growing due to the ever-increasing trend of using combustible materials in building facades. The main scope of this work is to investigate the fundamental physical phenomena a...

The ventilated façade (VF) system is a double-wall construction, comprising an external lightweight cladding panel and the building's façade, which is used to increase the indoor comfort level (e.g. temperature, humidity) in buildings. Literature reports on VF systems focus mainly on investigating their behavior in terms of energy consumption reduc...

The use of phase-change materials (PCM) to improve the performance of conventional solar walls (SWs) has been recently proposed. A holistic analysis of the thermal and energy performance of a PCM-enhanced SW is performed by employing numerical simulations on two different physical scales. Initially, a computational fluid dynamics tool is used to in...

The main scope of this work is to investigate the fundamental physical phenomena associated with Externally Venting Flames (EVF) and the factors influencing their development. In this context, a series of fire experiments is conducted in a medium-scale compartment-façade configuration; an n-hexane liquid pool fire is utilized, aiming to realistical...

The failure characteristics under fire conditions of a load bearing drywall system consisting of light cold-formed steel (CFS) studs, sheathed with a double layer of gypsum plasterboards and mineral wool insulation, are investigated. For that purpose, advanced numerical analyses of the wall assembly exposed to the standard ISO 834 fire curve are pe...

Motivated by the extensive use of the Molotov cocktail in recent urban riots in Greece, an experimental investigation of the fire behaviour of the Molotov cocktail and the effectiveness of relevant suppression techniques is performed. During the first testing phase, a series of glass bottle impact tests were performed, aiming to investigate the geo...

In a fully developed under-ventilated compartment fire, flames may spill out of external openings (e.g. windows); Externally Venting Flames (EVF) pose a significant risk of fire spreading to adjacent floors or buildings. The main scope of this work is to comparatively assess a range of fire engineering design correlations used to describe the exter...

Solar walls can be used to increase the overall energy efficiency of a building. Phase Change Materials (PCM) are capable of increasing the effective thermal mass of building elements, thus decreasing the overall energy consumption. Recently, the incorporation of PCM in a solar wall has been proposed, aiming to increase the total energy efficiency...

Solar walls can be used to increase the overall energy efficiency of a building. Phase Change Materials (PCM) are capable of increasing the effective thermal mass of building elements, thus decreasing the overall energy consumption. Recently, the incorporation of PCM in a solar wall has been proposed, aiming to increase the total energy efficiency...

Solar walls can be used to increase the overall energy efficiency of a building. Phase Change Materials (PCM) are capable of increasing the effective thermal mass of building elements, thus improving the overall energy consumption. Recently, the incorporation of PCM in a solar wall has been proposed, aiming to increase the total energy efficiency o...

Externally Venting Flames (EVF) may emerge in a fully developed under-ventilated compartment fire, thus significantly increasing the risk of fire spreading to adjacent floors or buildings. EVF related risks are constantly growing due to the ever-increasing trend of using combustible materials (e.g. insulation) in facades to enhance building energy...

New trends in building energy efficiency include thermal storage in building elements that can be achieved via the incorporation of Phase Change Materials (PCM). Gypsum plasterboards enhanced with micro-encapsulated paraffin-based PCM have recently become commercially available. This work aims to shed light on the fire safety aspects of using such...

In a compartment fire, Externally Venting Flames (EVF) may significantly increase the risk of fire spreading to adjacent floors or buildings, especially today that there is an ever-increasing trend of using combustible materials in building facades. The main scope of this study is to investigate the fundamental physical phenomena governing EVF deve...

Κατά την περίοδο της πλήρως ανεπτυγμένης φάσης μιας τυπικής φωτιάς σε κτίριο, οι φλόγες ενδέχεται να εξέλθουν από το χώρο της αρχικής έναυσης μέσω των ανοιγμάτων του (π.χ. παράθυρα, θύρες). Οι Φλόγες Εξερχόμενες από Κτίριο (ΦΕΚ) ενισχύουν σημαντικά τον κίνδυνο εξάπλωσης μιας φωτιάς σε παρακείμενους ορόφους ή κτίρια. Σήμερα, με στόχο τη βελτίωση της...

A full-scale compartment fire test was performed to assess gypsum plasterboards and wood based panels as cladding materials for the fire protection of light and massive timber elements. The test compartment was constructed using both the timber frame and the cross laminated timber techniques; a wood crib was used to achieve realistic fire condition...

Accurate modelling of preignition chemical phenomena requires a detailed description of the respective low-temperature oxidative reactions. Motivated by the need to simulate a diesel oil spray evaporation device operating in the "stabilized" cool flame regime, a "tabulated chemistry" tool is formulated and evaluated. The tool is constructed by perf...

The ability of currently available Computational Fluid Dynamics (CFD) tools to adequately describe Externally Venting Flames (EVF) is assessed, aiming to demonstrate compliance with performance-based fire safety regulations. The Fire Dynamics Simulator (FDS) CFD tool is used to simulate the EVF characteristics in a corridor-compartment-façade confi...

Phase Change Materials (PCM) can be used for thermal energy storage, aiming to enhance building energy efficiency. Recently, gypsum plasterboards with incorporated paraffin-based PCM blends have become commercially available. In the high temperature environment developed during a fire, the paraffins, which exhibit relatively low boiling points, may...

A comparative assessment of internal versus external thermal insulation systems for energy efficient retrofitting of residential buildings is performed by means of detailed numerical simulations. A 99.6 m2 one-storey apartment located at a mid-level of a multi-storey building is utilized as a “benchmark” case; the external walls of the building are...

Gypsum plasterboard wall assemblies are extensively used as cladding material for walls, floors and ceilings, as well as a means for passive fire protection of timber structures. The good fire resistance characteristics of gypsum plasterboards are mainly owed to the gypsum “dehydration” process, occurring between 80 °C and 250 °C, where large quant...

Carbon monoxide (CO), a highly toxic gas, is produced during the incomplete combustion of carbon-based fuels. In indoor environments, high CO concentrations constitute a serious occupational health hazard; this is especially true in the case of automotive repair shop (ARS) employees who are exposed on a daily basis to vehicle exhaust streams. The p...

Historic buildings can present significant thermal energy consumption variations and thus can have a considerable impact in the total energy demand of the building sector in the EU [1]. In order to characterize and assess the energy efficiency of a building, real-time monitoring of its thermal behaviour, via the collection of detailed information o...

Wood, used as a building construction material, offers a range of advantages in terms of cost, time for construction, energy efficiency and sustainability. Modern timber construction is able to exhibit high anti-seismic and fire-safety performance, which is at least on a par with more “conventional” construction techniques (e.g. concrete, steel). F...

Η ενσωμάτωση Υλικών Αλλαγής Φάσης (ΥΑΦ) στον όγκο ενός δομικού στοιχείου αποτελεί μια σύγχρονη τεχνική προκειμένου να αυξηθεί η θερμική του μάζα και συνεπώς να βελτιωθεί η θερμική συμπεριφορά και ενεργειακή απόδοση όλου του κτιρίου. Πρόσφατα έγιναν εμπορικά διαθέσιμες γυψοσανίδες (κύριοι αντιπρόσωποι των υλικών ξηράς δόμησης) με ενσωματομένα ΥΑΦ, π...

Gypsum "dehydration" phenomena, occurring when gypsum plasterboard wall assemblies are exposed to a high temperature environment, result in water vapour production and subsequent dispersion in the fire compartment; however, these phenomena are commonly neglected in relevant Computational Fluid Dynamics (CFD) simulations. In order to investigate the...

Phase Change Materials (PCM) can be used for thermal energy storage, aiming to enhance building energy efficiency. Recently, gypsum plasterboards with incorporated paraffin-based PCM blends have become commercially available. In the event of a fire, building elements are exposed to substantially high temperatures; in this case, paraffins, exhibitin...

The incorporation of Phase Change Materials (PCM) into building elements may affect favourably the overall building energy consumption. Common PCM added to gypsum plasterboards consist of paraffins. In the event of a fire, building elements may be exposed to substantially high temperatures; paraffins, exhibiting relatively low boiling points, may e...

A CFD simulation is performed in a two-storey residential building subjected to a typical domestic kitchen fire. The building is constructed using a structural steel frame configuration combined with dry-wall systems. The addition of Phase Changing Materials (PCM) into the gypsum plasterboard structure is known to improve the building's energy util...

The Fire Dynamics Simulator CFD code is used to study the thermal behaviour of a two-storey residential house subjected to a typical domestic fire scenario. The fire resistance behaviour of the building is evaluated considering two alternative building techniques; steel-skeleton combined with drywall systems and reinforced concrete with brick walls...

Diesel fuel is used in a variety of technological applications due to its high energy density and ease of distribution and storage. Motivated by the need to use novel fuel utilization techniques, such as porous burners and fuel cells, which have to be fed with a gaseous fuel, a Diesel fuel evaporation device, operating in the “Stabilized Cool Flame...

The sections in this article are Introduction Theory Phenomenology Negative Temperature Coefficient ( NTC ) Stabilized Cool Flames Chemical Kinetics Applications Liquid Fuel Evaporation for Premixed Combustion Liquid Fuel Reforming for Fuel Cell Applications Internal Combustion Engines Knocking Low‐Temperature Combustion and HCCI Engine...

A CFD tool is used to simulate a full-scale two-storey residential building subjected to a typical domestic fire. The detailed numerical simulation of the occurring physical and chemical phenomena allows the investigation of the developing flow-field, the fire spreading characteristics, as well as the thermal behaviour of the construction materials...

Fire protection systems in buildings are commonly regulated using prescriptive-based codes and standards, which exhibit small flexibility for innovative solutions and cost-effective designs. Performance-based fire safety design can alleviate such restrictions and several countries have started to adopt such methodologies in the recent years. In thi...

Seven n-heptane oxidation chemical kinetic mechanisms of varied complexity are compared aiming to assess their performance in simulating the cool flame oxidative behaviour of diesel oil, as well as to investigate the validity of the utilization of n-heptane as a “surrogate fuel” for diesel oil. Computed temperature and species concentrations are co...

Controlled liquid fuel droplet evaporation under "stabilized cool flame" (SCF) conditions can lead to a homogeneous, heated air-fuel vapour mixture that can be subsequently either burnt or utilized in fuel reforming of fuel cell applications. In this work, an "in-house" Computational Fluid Dynamics (CFD) code is used to simulate the turbulent, two-...

Carbon monoxide (CO) is a highly toxic gas, which is produced by the incomplete combustion of any carbon-based fuel. The level of CO concentration in indoor environments constitutes a serious health hazard for occupational safety, especially for car-repair shop employees who are exposed on a daily basis to vehicle exhaust fumes. However, the topic...

In a Diesel oil evaporation device operating in the “Stabilized Cool Flame” (SCF) regime, a thermo-chemically stable low-temperature oxidative environment is developed, thus preventing the mixture from being ignited. In this case, a well-mixed, heated air-fuel vapour gaseous mixture is produced, which can be subsequently fed either to premixed comb...

The major objective of this work is to numerically investigate the interacting physical and chemical phenomena that characterize the flow in a stabilized cool flame diesel fuel spray evaporation system. A two-phase RANS computational fluid dynamics code has been developed and used to predict the characteristics of the developing turbulent, multipha...

The interacting physical and chemical phenomena that characterize the flow in a Stabilized Cool Flame Diesel oil evaporation device are simulated by using a commercial CFD code to predict the developing turbulent, multiphase, multi-component and reactive flow-field. Modelling of the evaporating and reacting spray characteristics is realized using,...

A numerical investigation of the turbulent, multi-component and reactive flow-field that develops in a Stabilized Cool Flame Diesel fuel spray evaporation system, using a Computational Fluid Dynamics (CFD) code is presented. The physical and chemical phenomena are described by solving the respective mass, momentum, species, thermal and turbulent en...

A numerical code for the simulation of the one-dimensional heat transfer through a commercially available gypsum board exposed to fire is presented. A parametric study regarding the physical properties of the gypsum is carried out. The predictions obtained with the in-house developed code are in good agreement with experimental data, when temperatu...

The paper provides an overall assessment of the environmental effects of co-incineration of cutting oil emulsions in cement plants through the quantification of emissions of trace species, namely polychlorinated dioxins and furans and heavy metals. A detailed kinetic model for dioxin formation and destruction is developed and it is shown that under...

The major objective of this work is to numerically investigate the interacting physical and chemical phenomena that characterize the flow in a Stabilized Cool Flame Diesel fuel spray evaporation system. Toward this end, an in-house developed, two-phase RANS Computational Fluid Dynamics code has been used to predict the characteristics of the turbu...

The major objective of this work is to numerically investigate the interacting physical and chemical phenomena that characterize the flow in a Stabilized Cool Flame Diesel fuel spray evaporation system. Toward this end, an in-house developed, two-phase RANS Computational Fluid Dynamics code has been used to predict the characteristics of the turbul...

An “in-house” computational fluid dynamics code implementing a Euler-Lagrange approach is extended by incorporating the Euler-Euler (two-fluid model) approach, to improve prediction capabilities of flow and thermal characteristics of turbulent evaporating sprays. The performance of both approaches is assessed by comparing predictions with experimen...

The paper provides an overall assessment of the environmental effects of co-incineration of cutting oil emulsions in cement plants through the quantification of emissions of key pollutants, namely NOx, CO and VOC. Two realistic scenarios are considered. In the first, the cutting oil emulsion is injected directly into the rotary kiln while the secon...

The work comparatively assesses the performance of seven chemical kinetic mechanisms of variable complexity (ranging from 22 up to 645 species). The results are intended for implementation in the numerical investigation of the thermo-chemical behaviour of atmospheric pressure diesel oil “stabilized cool flame” reactors. N-heptane is used as a “surr...

A range of n-heptane oxidation kinetic mechanisms are comparatively assessed in the frame of understanding the physico-chemical characteristics of an atmospheric pressure, non-igniting, Diesel oil spray, “stabilized cool flame” reactor. A large variety of detailed and reduced chemical kinetic schemes are currently available in the open literature...

The scope of this work is to analyse the thermal field in a “stabilized cool – flame” (SCF) reactor, where a liquid-fuel (diesel) spray is first evaporated and then the fuel steam produced is only partially oxidized. This low temperature oxidation process is termed as the “cool flame phenomenon” and couples mass and heat transfer phenomena with “lo...

The paper comparatively assesses the computational performance of a selected number of theoretical and semi-empirical liquid droplet evaporation models that focus on thermodynamic non-equilibrium effects, physical property estimation methods and convective and blowing effect corrections for the calculation of the heat and mass transfer rates. Three...

The paper focuses on the numerical simulation of diesel oil droplet evaporation in a “stabilized cool flame” environment. For this purpose, a dedicated model is formulated, correlating cool flame induced heat release with local temperature and fuel concentration values. The developed model is capable of adequately describing the main physicochemica...

Droplet evaporation in a “stabilized cool flame” environment leads to a homogeneous, heated air–fuel vapor mixture that can be subsequently either burnt or utilized in fuel-reforming applications for fuel cell systems. The paper investigates the locally occurring physico-chemical phenomena in an atmospheric pressure, diesel spray, stabilized cool f...