Aluminum because of its high
enthalpy of combustion has been added to
energetic materials. Seve... more Aluminum because of its high
enthalpy of combustion has been added to
energetic materials. Several research efforts have
been directed to understand the mechanism and
model the oxidation of aluminum particles. In
this work, a two dimensions and time dependent
thermal model is developed and assessed to
describe the interrelated processes of Aluminum
particle oxidation. The thermal model consists of
thermal radiation, forced convection and thermal
conduction and oxygen diffusion and surface
reactions. It is assumed the aluminum particle is
coated with Aluminum oxide layer.
Olefins are crucial building blocks for petrochemical industry, serving as raw materials for the ... more Olefins are crucial building blocks for petrochemical industry, serving as raw materials for the production of various products such as plastics, synthetic fibers, detergents, solvents, and other chemicals. In FCC, heavy petroleum feedstocks are injected into a catalytic cracking unit, where they are mixed with a catalyst. The catalyst aids in breaking down the large hydrocarbon molecules into smaller fragments, including olefins like Propylene and Ethylene. These polymerization reactions occur at high temperatures. They demand that heat removal occurs as quickly as possible in order to control the reactor temperature and to avoid “hot spots” in the Regenerator or localized oxidation reactions (and to avoid creep rupture of the regenerator steel cladding). The cooling of the regenerator cladding surface can be achieved by impinging water droplets (spray), ejected from a spray nozzle. Spray cooling can provide uniform cooling and handle high heat fluxes in both a single phase and two...
Hydrogen sulfide (H2S) is considered a toxic and corrosive gas, commonly found in natural gas, cr... more Hydrogen sulfide (H2S) is considered a toxic and corrosive gas, commonly found in natural gas, crude oil, and other fossil fuels. This corrosive gas may lead to stress corrosion cracking (SCC). This phenomenon is caused by the combined influence of tensile stress and a corrosive environment. This may lead to the sudden failure of normally ductile metal alloys, especially at an elevated temperature. Desulfurization is the process of removing H2S from these fuels to reduce their harmful environmental and health impacts. Ionic liquids (ILs) have shown great potential for application as liquid absorbents for H2S extraction because of their advantages such as non-volatility, functionality, high carbon solubility and low energy requirements for regeneration. The proposed hydrogen sulfide extraction system consists of a tube, membrane and shell. 1-ethyl-3-methylimidazolium (emim)-based ionic liquids with bis-(trifluoromethyl) sulfonylimide (NTf2) anion has been selected due to its high H2S...
Inhalational anesthesia is supplied through an assisted ventilation system. It is mostly composed... more Inhalational anesthesia is supplied through an assisted ventilation system. It is mostly composed of xenon or nitrous oxide, halogenated hydrocarbons (HHCs), and oxygen. In order to reduce costs of the anesthesia compounds, the remaining anesthetics present in exhalation are recycled and reused, in order to minimize the amount of fresh anesthesia. An alkali hydroxide mixture (called soda lime) is employed in order to remove CO2 from the exhalation. However toxic compounds may be formed during the reaction of soda lime with halogenated hydrocarbons. Ionic liquids (ILs) have several advantages such as non-volatility, functionality, high carbon solubility, and low energy requirements for regeneration. In the framework of this research, carbon dioxide removal with ionic liquids has been numerically studied. COMSOL multi-physics finite element software has been applied. It solves the continuity, fluid flow, and diffusion equations. A new algorithm has been developed for calculating the i...
Large Eddy Simulation (LES) and Thermodynamic study have been performed on Organic Rankine Cycle ... more Large Eddy Simulation (LES) and Thermodynamic study have been performed on Organic Rankine Cycle (ORC) components (boiler, evaporator, turbine, pump, and condenser). The petroleum Coke burner provided the heat flux needed for the butane evaporator. High boiling point fluid (called phenyl-naphthalene) has been applied in the ORC. The high boiling liquid is safer (steam explosion hazard may be prevented) for heating the butane stream. It has best exergy efficiency. It is non-corrosive, highly stable, and flammable. Fire Dynamics Simulator software (FDS) has been applied in order to simulate the pet-coke combustion and calculate the Heat Release Rate (HRR). The maximal temperature of the 2-Phenylnaphthalene flowing in the boiler is much less than its boiling temperature (600 K). Enthalpy, entropy and specific volume required for evaluating the heat rates and the power have been computed by employing the THERMOPTIM thermodynamic code. The proposed design ORC is safer. This is because th...
An advanced algorithm has been developed in order to analyze the performance of reboiling process... more An advanced algorithm has been developed in order to analyze the performance of reboiling process of crude oil flowing inside reboilers tubes. The proposed model is composed from Heptane fire heater and a tube array. The heat flux produced from burner is transferred to the crude oil flowing inside the tube. The computational model is composed of two phases—Simulation of fire by using Fire Dynamics Simulator software (FDS) version 5.0 and then a nucleate boiling computation of the crude oil. FDS code is formulated based on CFD (Computational Fluid Dynamics) of fire heater. The thermo-physical properties (such as: thermal conductivity, heat capacity, surface tension, viscosity) of the crude oil were estimated by using empirical correlations. The thermal heat transfer to evaporating two-phase crude oil mixture occur by bubble generation at the wall (nucleate boiling) has been calculated by using Chen correlation. It has been assumed that the overall convective heat transfer coefficient...
Thermodynamic analysis of Organic Rankine Cycle (ORC) was performed in this work. The Petroleum C... more Thermodynamic analysis of Organic Rankine Cycle (ORC) was performed in this work. The Petroleum Coke burner provided the required heat flux for the Butane Boiler. The simulation of pet-coke combustion was carried out by using Fire Dynamics Simulator software (FDS) version 5.0. Validation of the FDS calculation results was carried out by comparing the temperature of the gaseous mixture and CO2 mole fractions to the literature. It was discovered that they are similar to those reported in the literature. An Artificial Intelligence (AI) time forecasting analysis was performed on this work. The AI algorithm was applied to the temperature and soot sensor readings. Two Python libraries were applied in order to forecast the time behaviour of the thermocouple readings: Statistical model—ARIMA (Auto-Regressive Integrated Moving Average) and KERAS—deep learning library. ARIMA is a class of model that captures a suite of different standard temporal structures in time series data. Keras is a pyt...
FAME (biodiesel) is an alternative fuel that can be produced from vegetable oils. There is growin... more FAME (biodiesel) is an alternative fuel that can be produced from vegetable oils. There is growing interest in the research and development of renewable energy sources. A possible solution is a biofuel usable in compression-ignition engines (diesel engines) produced from biomass rich in fats and oils. This paper contains a new and safer design of an esterification reactor for producing FAME (biodiesel) by utilizing high boiling point fluid (called phenyl-naphthalene). CFD simulation of biodiesel production by using methyl imidazolium hydrogen sulfate ionic liquid has been carried out. Ionic liquids (ILs) are composed of anions and cations that exist as liquids at relatively low temperatures. They have many advantages, such as chemical and thermal stability, low flammability, and low vapor pressures. In this work, the ionic liquids have been applied in organic reactions as solvents and catalysts of the esterification reaction. The great qualities of high boiling temperature fluids, a...
CFD Simulation and Time Forecasting Modeling Behavior of Heptane Spray Burner by applying Artificial Intelligence (AI) Algorithms CFD Simulation and Time Forecasting Modeling Behavior of Heptane Spray Burner by applying Artificial Intelligence (AI) Algorithms
Recent fire disasters in European road tunnels have shown that fires in a tunnel represent high r... more Recent fire disasters in European road tunnels have shown that fires in a tunnel represent high risks. The users and the rescue services are endangered by heat and smoke while the tunnel is often damaged considerably. In the event of fire the temperature in tunnel rises extremely rapidly within a short amount of time. Large scale fire tests that maximum of 1200oC or even above could occur. The result is an increased risk of concrete spalling of the tunnel lining. Depending on depth and quantity of these spalling, the structure could be damaged seriously. A fire proof concrete is one relatively new and promising measure to avoid spalling of the tunnel lining during fire. The fire resistance of concrete can be improved by coating it with composite material. In this work CFD calculations have been carried out in order to study the tunnel fire growth on composite wall lining materials by using Fire Dynamic Simulation software (FDS). It has been applied in order to solve the turbulent fl...
The Potential of the Remote Sensing Method for Vehicle Inspection Programs
Results are presented of an assessment of the potential of the remote sensing technology to suppl... more Results are presented of an assessment of the potential of the remote sensing technology to supplement current inspection procedures regarding emissions from motor vehicles and to improve the process of identifying big polluters. About 20,000 vehicles were tested for CO, HC, CO2 and NOx emissions, using the remote sensing system manufactured by the MD Lasertech Co. More than 200 vehicles were tested also at idle in accordance with the current European inspection procedure. Methods of dirty and clean screening were checked and errors of commission as well as errors of omission were evaluated for various CO cut-points. Improvement of the inspection results was estimated, when compared with the data of two series of random roadside tests without remote sensing, which were carried out in 1997 and 2001. For the covering abstract see ITRD E122175.
A large amount of research has been performed to characterize the combustion properties and reduc... more A large amount of research has been performed to characterize the combustion properties and reduce the flammability of composite materials, although less is known about the structural behavior of composites in fire. Several studies have examined the effect of high temperature or fire on the load-bearing properties of polymer laminates and sandwich composites. This paper presents thermomechanical models for predicting the strength of polymer laminates loaded in tension or compression exposed to one-sided radiant heating by fire. The models predict the temperature rise and through-thickness temperature profile in a hot decomposing laminate exposed to fire. The models assume that one side of a laminate beam is evenly heated at a constant radiant heat flux. Calculation of the fire resistance demands determination of temperature distribution in the cross-section (heat-exposure model) and analysis of mechanical responses of the structure exposed to increased temperature (structural respon...
Unexpected releases of combustible vapors/gases can lead to explosions, which threaten the integr... more Unexpected releases of combustible vapors/gases can lead to explosions, which threaten the integrity of equipment and structures. Multiple explosions can destroy plants, jeopardize lives, and inflict large economic losses; outdated parts of the pipe system can leak flammable gas in air and pose the danger of explosion. Therefore, it is important to be able to predict explosion properties and to design pipes and storage tanks that can withstand such catastrophic events. Such efforts enable plant engineers to evaluate risks associated with their designs subject to various possible explosions. Pressure rises almost instantaneously because of the overpressure from an explosion causing structural damage or deformation of pipes and storage tanks. Explosive pressure and structural damage can be estimated with analytical and numerical tools. By using these computational tools, safe distances between equipment and structures can be assigned. In this work an algorithm has been developed in or...
Hydrogen could be a promising source fuel, and is often considered as a clean energy carrier as i... more Hydrogen could be a promising source fuel, and is often considered as a clean energy carrier as it can be produced by ethanol. The use of ethanol presents several advantages, because it is a renewable feedstock, easy to transport, biodegradable, has low toxicity, contains high hydrogen content, and easy to store and handle. Reforming ethanol steam occurs at relatively lower temperatures, compared with other hydrocarbon fuels, and has been widely studied due to the high yield provided for the formation of hydrogen. A new computational fluid dynamics (CFD) simulation model of the ethanol steam reforming (ESR) has been developed in this work. The reforming system model is composed from an ethanol burner and a catalytic bed reactor. The liquid ethanol is burned inside the firebox, then the radiative heat flux from burner is transferred to the catalytic bed reactor for transforming the ethanol steam mixture to hydrogen and carbon dioxide. The proposed computational model is composed of t...
An advanced algorithm has been developed in order to analyze the performance of re-boiling proces... more An advanced algorithm has been developed in order to analyze the performance of re-boiling process of crude oil flowing inside reboilers tubes. The proposed model is composed from Heptane fire heater and a tube array. The heat flux produced from burner is transferred to the crude oil flowing inside the tube. The computational model is composed of two phases—Simulation of fire by using Fire Dynamics Simulator software (FDS) version 5.0 and then a nucleate boiling computation of the crude oil. FDS code is formulated based on CFD (Computational Fluid Dynamics) of fire heater. The thermo-physical properties (such as: thermal conductivity, heat capacity, surface tension, viscosity) of the crude oil were estimated by using empirical correlations. The thermal heat transfer to evaporating two-phase crude oil mixture occur by bubble generation at the wall (nucleate boiling) has been calculated by using Chen correlation. It has been assumed that the overall convective heat transfer coefficien...
Levulinic acid (LA) has been ranked as one of the “Top 10” building blocks for future bio-refiner... more Levulinic acid (LA) has been ranked as one of the “Top 10” building blocks for future bio-refineries as proposed by the US Department of Energy. It is considered one of the most important platform molecules for the production of fine chemicals and fuels based on its compatibility with existing processes, market economics, and industrial ability to serve as a platform for the synthesis of important derivatives. Hydrogenation of LA to produce γ-valerolactone (GVL) is an active area of research due to the potential of GVL to be used as a biofuel in its own right and for its subsequent transformation into hydrocarbon fuels. This paper contains a new design for a simple, cost effective, and safe hydrogenation reactor for the transformation of levulinic acid to γ-valerolactone (GVL) by utilizing high boiling point organic fluid. The hydrogenation reactor is composed of a heating source—organic fluid (called “DOWTHERM A” or “thermex”) and the catalytic reactor. The advantages of high boili...
Different kinds of explosions are driven by the internal energy accumulated in compressed gas or ... more Different kinds of explosions are driven by the internal energy accumulated in compressed gas or superheated liquid. A well-known example of such an explosion is the burst of a vessel with pressure-liquefied substance, known as Boiling Liquid Expanding Vapor Explosion (BLEVE). Hot BLEVE accident is caused mainly by direct heating (pool fire or jet fire) of the steel casing at the vapor side of the tank to temperatures in excess of 400 °C. Thermal insulation around the tank can significantly reduce and retard the excessive heating of the tank casings in a fire. This will allow fire fighters enough time to reach the accident location and to cool the LPG (Liquid Petroleum Gas) tank to avoid the BLEVE, to extinguish the fire or to evacuate the people in the vicinity of the accident. The proposed algorithm addresses several aspects of the BLEVE accident and its mitigation: Computational Fluid Dynamic (CFD) Simulation of jet fire by using fire dynamics simulator (FDS) software by using la...
The demands for high power and low emissions put focus on energy efficiency when developing new e... more The demands for high power and low emissions put focus on energy efficiency when developing new engines. An important part is the UAV engine cooling system, which cools the engine structure below damaging temperatures. For high temperatures in the cooling system there is a risk that boiling occurs and while the initial nucleate boiling enhances the cooling effect, the subsequent Film boiling decreases the heat transfer drastically. It is important to understand the benefits and limitations of various fluids when designing a two-phase cooling system. This paper proposes an alternative organic coolant. Its normal application range is 15°C to 400°C, and its pressure range is from atmospheric to 10.6 bar. DOWTHERM A fluid possesses unsurpassed thermal stability at temperatures of 400°C. This fluid, in both the liquid and vapor form, is noncorrosive toward common metals and alloys. Even at the high temperatures involved, the equipment usually exhibits excellent service life. ...
IOSR Journal of Mechanical and Civil Engineering, 2017
In this work a new algorithm has been developed in order to calculate the soot particles absorpti... more In this work a new algorithm has been developed in order to calculate the soot particles absorption coefficient during Heptane pool tunnel fire. It is based on the Fire Dynamics Simulator (FDS) results. In the FDS model, the combustion is represented by means of the mixture fraction with a single step chemical reaction model. Large Eddy Simulation (LES) is used to model the dissipative processes. HITRAN database was applied in order to calculate the refractive indices of soot particles (n, k). CFD results show that the soot absorption coefficient is strongly influenced by the concentration and the temperature fields. It was found out that soot particle tends to concentrate near the tunnel ceiling. This phenomenon occurs due to thermal buoyancy forces. The thermal gradient causes the flow to flow towards the ceiling. This proposed algorithm can be implemented in smoke detection systems and in fire simulation codes.
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Papers by Alon Davidy
enthalpy of combustion has been added to
energetic materials. Several research efforts have
been directed to understand the mechanism and
model the oxidation of aluminum particles. In
this work, a two dimensions and time dependent
thermal model is developed and assessed to
describe the interrelated processes of Aluminum
particle oxidation. The thermal model consists of
thermal radiation, forced convection and thermal
conduction and oxygen diffusion and surface
reactions. It is assumed the aluminum particle is
coated with Aluminum oxide layer.