Mohamed I. Hassan

Flow Structure Of A Fixed-frame Type Firewhirl

This paper reports the results of both experimental and numerical investigations on a laboratory-scale fixed-frame type fire whirl. We designed a fixed-frame type fire whirl generator consisting of two vertically oriented split PMMA cylinders which are placed in an off-center location to create a small compartment with a slit at each end. At the center of the compartment floor, a 5 cm-diameter 1-propanol pool fire generated upward buoyancy flow and fresh air entering the compartment through the slits, generating swirl motion in the compartment. This is a fixed-frame type fire whirl. We measured transient 2-D radial, tangential, and axial velocity profiles with 2-D particle image velocimetry (PIV). The radial and tangential velocity profiles were measured at four different heights (5, 10, 15, and 20 cm) along the axis of the fire whirl, while the axial velocity profiles were measured at 10 cm in the axial height. We also measured relative temperature distributions of the fire whirl with an infrared thermograph technique. These measurements show that both the tangential velocity and the absolute value of radial velocity increase with an increase in the radial distance, while they remain relatively constant along the axis. Our IR data also show that the relative temperature map stays unchanged along the axis. The radial locations where the maximum radial and tangential velocity were measured approximately coincide and are at about 3.5 cm on the radial coordinate, while the visible spinning flame location is at about 1.2 cm. This shows a difference in the velocity structure between open pool fires and fire whirls, because the location of the maximum flow velocity and visible flame approximately coincides for laminar open pool fires. A simple laminar 2-D axisymmetric CFD model was developed to simulate these measured flow and temperature structures created by the fire whirl, and reasonable agreement was obtained.

An experimental study of heat pipe performance using nanofluids

Heat pipe cooling is widely used in computer processors. Advances in microprocessor technology have resulted in reduced heat transfer surface area. Maintaining an efficient cooling process is therefore challenging. The main goal of this experimental study is to perform a parametric study on heat pipe performance using nanofluids. Nanofluids of 1 and 3 vol% of alumina nanoparticles of 20–50 nm diameters in deionized water versus deionized water as a base fluid were considered in the present study. The nanofluids are prepared in our laboratory using two-step method. The nanofluids thermal properties are measured to confirm the properties enhancement that could indicate a corresponding performance enhancement of the heat pipe. A 10 mm inner diameter, 200 mm long brass tube with 50 mm long evaporator, and 50 mm long water cooled condenser were used. Heat pipe wall temperature is reduced with nanofluids as is the temperature difference between the evaporator and condenser. The thermal diffusivity of the nanofluids is increased by 10%. The pipe pressure in case of deionized water was higher than the corresponding one for the nanofluids by 20–32%.

CFD Comparison of Immersed Heater and Open Fire Burner Designs for Casting Furnaces

In essence, only a small fraction of the heat supplied to the conventional aluminum casting (holding) furnaces is used up for its main purpose — alloying and maintaining the metal set point temperature. As the metal introduced to furnace is most often already in the molten phase, most of the energy supplied via open fire burners is usually lost through the furnace walls, door openings and the flue gas. In this theoretical study, fire-tubes are immersed in the metal as an alternative for the conventional open fire burners. Using the Finite Volume Method (FVM), Computational Fluid Dynamics (CFD) models, with heat transfer and combustion incorporated, are developed for both design options, using the commercial code StarCCM+. Thermodynamic analyses are adapted in making a comparison between both designs. In both options, the non-premixed flame (heat source) is simulated using the Eddy Break Up (EBU), 3-step reaction models. The participating media radiation models are adapted for a comprehensive estimation of the radiation heat transfer within the furnace. Turbulence within the flame is modeled using the standard K-epsilon model. Results show that the immersed fire tube improved the furnace’s thermal efficiency.

Mathematical Model of Cooling of a Stopped Pot and Its Validation

In aluminum reduction pot technology, the potshell is used for several generations. After each shut down the potshell is cooled by free convection and radiation. This cooling takes from five to nine days depending on the surrounding temperature. Cooling by spraying water on the potlining is used in some aluminum plants; this reduces the cooling time to less than one day but this method can be harmful for the potshell and for the environment.

On the Cast House Exergy Management

The energy efficiency of aluminum casting furnaces has been widely reported. However, the conventional energy efficiency analyses are based on the first law of thermodynamics which do not shed adequate light on the processes’ degradation of energy. This just gives a general idea of the furnace’s performance with no reference to possible improvement strategies. In this study, we apply exergy analyses on the aluminum holding and melting furnaces to identify the location and causes of energy degradation. The exergy analyses which are based on a real life furnace conditions highlight the possible locations for technology improvement in a typical cast house. With this established, methods of minimizing the cast house’s exergy losses are assessed.

Numerical Simulation of Degassing Phenomena in Direct Chilled Casting Process under External Static Magnetic Field on Flow Pattern in Slab Mold

For good quality billet, metal degasing is important consideration in billet casting. In-line degasser processes help to remove 61 to 66% of the dissolved gas. An improved billet quality can increase extrusion speed. A model of degassing delineates the most important key factors for optimization of product design for high quality, productivity and cost savings using computer simulations. The present work focuses on aluminum direct chilled casting process with gas injected in the mold through a submerged entry nozzle. The effects of gas into the melt and a direct casting magnetic field on the mold fluid flow are studied. Considering the effect of complex flow, injection and heat transfer on the gas bubble size the particles model reveals to be an efficient method to study the degassing phenomenon. However, the model treats the gaseous phase as bubbles with multiple sizes providing a new approach to simulate multiphase flow in continuous casting.

Thermo-Mechanical Properties of Wrought Aluminium Alloys Produced from Scrap Mixing

A significant demand in the use of aluminium alloys, most especially in the automobile industries, has been recorded over the past few decades. This is due to light-weight properties of aluminium alloys which when considered in many industries has a significant increase on the fuel efficiency economy of automobiles. The sustainable production of aluminium from recycling of scraps helps in better energy efficiency, cost effectiveness and reducing carbon footprints. Scraps for recycling can easily be obtained through the post-consumers and post-manufacturers. 100% compatibility of the feedstock from these scraps has been a major challenge in the automotive industry. It is very difficult to get alloys which have compatibility of 100% substitution rate. This study compares and predicts using JMatPro the thermo-physical and mechanical properties of these alloys after mixing and the aftermath effects on their service life

Furnace Modeling for Efficient Combustion Gas Circulation

In the conventional open flame aluminum casting furnace, a large proportion of the heat generated by the burners is wasted. Proper circulation of the flame’s combustion gases could increase the fraction of heat transferred to the molten metal. In this work, we develop models for the aluminum holding furnace with an aim of optimizing the exhaust gas dynamics, for a more efficient casting process. Using the Finite Volume Method (FVM), fully coupled combustion, heat transfer and fluids dynamics models of the furnace are developed, on the commercial code StarCCM+. The exhaust and burner locations of a typical furnace design are varied to examine the effect of combustion gasses recirculation on the furnace’s first law efficiency. In all models, the non-premixed flame (heat source) is simulated using the Eddy Break Up (EBU), 3-step reaction mechanism. The participating media radiation models are adapted for calculating the radiation heat transfer. Turbulence is modeled using the standard K-epsilon approach. Overall, our results highlight ventilation design considerations for the casting furnace.

Solar Energy Capture: Methods of Optimizing Nanofluid‐Based Volumetric Solar Flow Receivers

Appropriately selected and prepared nanofluids have promised improved volumetric absorption for solar energy harvesting. This study explored methods of optimizing a graphite-Therminol VP-1 nanofluid volumetric solar flow receiver. Previous studies provided a means of selecting the optimum physical parameters of a rectangular flow receiver via a 2D analytical model. This model has been extended to include a specular reflective base, which demonstrated improvements in the overall efficiency. The refractive index of the absorbing medium was included, causing a spectral shift of incoming radiation. Smaller nanoparticle volume fractions were therefore required to achieve the optimum efficiency, which was also determined using the extended analytical model. A more realistic numerical model, prepared using Ansys Fluent, indicated that receivers with partially diffuse reflecting bases exhibited higher temperatures near the base, thereby minimizing surface losses and increasing average temperatures. The magnitude of these increases, however, may not warrant the use of these types of reflectors.

An On-Demand Hydrogen Cell for Automobile Fuel Consumption Efficiency

The effect of a homemade complete hydroxyl system on automobiles’ performance under real operation conditions has been investigated on three gasoline-fueled four-stroke four-cylinder engine automobiles. All measured parameters were carried out by using the AVL DiTEST Abgas test and the Lancom 9 gas analyzer. The exhaust gases CO2, O2, CO, NOx, and CxHy, at the exhaust tail pipe and before the catalytic converter were measured. A significant reduction of 35–45% in the specific fuel consumption was observed. An in-cylinder chemical reaction model was developed to understand the impact of hydroxy gas on the combustion chemistry of engine. The in-cylinder pressure results showed about 3-bar increase in pressure peak at 1.2% H2 addition to the engine air/fuel mixture. Also, the mixture ignition temperature was reduced from 600 to 560 K. The exhaust gas species showed a 12% increase in H2O. Furthermore, the comparative t-test showed that the average CO volumetric concentration was reduced by 12%, while the average O2 was increased by 11%. On the other hand, hydrocarbon concentration was randomly varying with a maximum reduction of 35% at 2420 rpm. The origin of the observed significant influence of introducing H2 and O2 molecules on the combustion reaction mechanism and flame front stability has been explained.