Experimental Studies Of Spray And Combustion Characteristics Of Biomass Derived Fuels In A Constant Volume Combustion Chamber

Concern with fossil fuel depletion and environmental degradation promotes the use of renewable energy sources in particular biomass derived fuel for automotive and power generation applications. In this study, spray characteristics of Refined Palm Oil (RPO) were studied in a Constant Volume Combustion Chamber (CVCC), and compared to conventional fuel such as gasoline and diesel. For gaseous fuel, Producer Gas (PG) derived from biomass gasification were studied as its usage in IC engines degrades the engine performance at about 30-35 %. An optical CVCC with spray measurement setup was used to measure spray tip penetration, spray cone angle and spray area of liquid fuel (gasoline, diesel and palm oil blends). Injection starting pressure was varied by increasing or decreasing the thickness of adjusting shims of the injector. The starting injection pressures were studied at 20, 30 and 34 MPa. For Compressed Producer Gas (CPG) combustion and optimization study, it was tested at different Mass Increase Factor (MIF) of 0, 25 and 50 % of the air and fuel mixture. The optimization was conducted using Design of Experiments (DOE) method

Effect of cylinder deactivation strategies on engine performances using one-dimensional simulation technique

In order to meet consumer and legislation requirements, big investments on key technology strategies have been made to ensure fuel consumption is reduced. Recent technologies for gasoline engines are lean combustion technologies (including direct injection and homogenous charged compression ignition), optimizing intake and exhaust valve timing with valve lift and also cylinder deactivation system (CDA) have been practised to improve the engine efficiency. The purpose of this study is to investigate the engine behavior when running at different cylinder deactivation (CDA) strategies. One-dimensional engine model software called GT-Power is used to predict the engine performances. Five strategies were considered namely normal mode, spark plug off mode, cylinder deactivation mode, intake normal with exhaust off mode, and intake off with exhaust normal mode. Engine performance outputs of each strategy are predicted and compared at BMEP of 3 bars with engine speed of 2500 rpm. Also, the effect of CDA strategies on in-cylinder pressure and pumping loss are performed. The study shows that all of these cylinder deactivation strategies are capable of reducing the pumping loss (PMEP) and fuel consumption, thus increasing the thermal efficiency of the engine. The results suggest that the most beneficial strategy for activating CDA is for the case whereby both the intake and exhaust valves are kept closed. This CDA mode capable of increasing brake thermal efficiency up to 22% at entire engine speeds operation. This strategy successfully reduced the BSFC. It was found that most of these cylinder deactivation strategies improve the engine performance during part load engine condition

Effects of Heat Generation/Absorption on a Stagnation Point Flow Past a Stretching Sheet Carbon Nanotube Water-Based Hybrid Nanofluid with Newtonian Heating

This study investigates the mathematical modelling of heat generation/absorption effect on the convective flow of single wall carbon nanotube-copper (SWCNT-Cu)/water hybrid nanofluid towards a stagnation point past a stretching sheet with Newtonian heating. The set of governing equations in the form of non-linear partial differential equations are first transform using the similarity transformation technique then solved numerically by the Runge-Kutta-Fehlberg (RKF45) method in Maple software. The numerical solutions were obtained for the surface temperature, the heat transfer coefficient and the skin friction coefficient as well as the velocity and the temperature profiles. The features of the flow and heat transfer characteristics for various values of the stretching parameter, the conjugate parameter, the nanoparticle volume fraction parameter and the heat source/sink parameter are analyzed and discussed. It is found that effects of hybrid nanoparticles are more significant for lower stretching parameter and for large conjugate parameter values, as well as the heat generation/absorption

The effect of torrefaction on oil palm empty fruit bunch properties using microwave irradiation

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Effect of torrefaction on oil palm empty fruit bunch pelletization

This paper focuses on the properties of raw and torrified pellet from EFB by varying different parameters including energy consumption, moisture adsorption, Meyer  hardness test and pellet density. To save storage space and transport costs, it can be compressed into fuel pellets of high physical and energetic density. The pelletizing  properties were determined using single pellet press and pellet stability was determined by compression testing. Pelletization of raw and torrified empty fruit bunch (EFB) from compression single pellet press (SPP) was investigated to quantify the energy consumption and pellet properties including moisture adsorption, pellet density and Meyer hardness. Energy consumption for torrified EFB pellet were significantly higher than those for raw EFB pellet, while the moisture adsorption rate of torrified EFB pellets increased with increasing the severity of torrefaction.Keywords: oil palm empty fruit bunch (EFB) torrefaction; pelletization

Free convection boundary layer flow from a vertical truncated cone in a hybrid nanofluid

The present study investigates the mathematical model of free convection boundary layer flow from a vertical truncated cone immersed in Cu/water nanofluid and Al2O3-Cu/water hybrid nanofluid. The governing non-linear equations are first transformed to a more convenient set of partial differential equations before being solved numerically using the Keller-box method. The numerical values for the reduced Nusselt number and the reduced skin friction coefficient are obtained and illustrated graphically as well as temperature profiles and velocity profiles. Effects of the alumina Al2O3 and copper Cu nanoparticle volume fraction for hybrid nanofluid are analyzed and discussed. It is found that the high-density and highly thermal conductivity nanoparticles like copper contributed more in skin friction and convective heat transfer capabilities. The appropriate nanoparticles combination in hybrid nanofluid may reduce the friction between fluid and surface but yet still gave the heat transfer capabilities comparable to metal nanofluid

Stagnation Bioconvection Flow of Titanium and Aluminium Alloy Nanofluid Containing Gyrotactic Microorganisms over an Exponentially Vertical Sheet

The pivotal aim of this research is to address a natural stagnation bioconvection flow of a hybrid nanofluid containing gyrotactic microorganisms over an exponentially stretching and shrinking vertical sheet. The mathematical formulation of simplified Navier-Stokes equations is made in the presence of a few parameters such as Prandtl number, concentration to thermal buoyancy ratio, microorganism to thermal buoyancy ratio, Lewis number, bioconvection Peclet number, bioconvection Lewis number, microorganisms concentration difference and buoyancy parameter. The two types of nanofluid containing titanium alloy (Ti6Al4V) and aluminium alloy (AA7075) immersed in water are considered for the investigation. In the analysis, the governing partial differential equations (PDEs) are transformed into a set of ordinary differential equations (ODEs) by a similarity transformation. The resulting equations are rewritten in MATLAB software through the Bvp4c method to obtain the solutions. The effects of hybrid nanofluid of titanium alloy (Ti6Al4V) and aluminium alloy (AA7075), microorganisms’ concentration difference parameter, and bioconvection Lewis Number are observed in this mathematical model in the presence of stretching and shrinking sheets. The numerical values are obtained for the skin friction coefficient, local Nusselt number, local Sherwood number, and local density of motile microorganisms for the reporting purpose. In addition, the profiles of the velocity, temperature, concentration, and microorganism are visualized as the main findings of this article

Boundary layer flow of williamson hybrid ferrofluid over a permeable stretching sheet with thermal radiation effects

This research investigated the convective boundary layer flow and heat transfer of Williamson hybrid ferrofluid over a permeable stretching sheet with thermal radiation effects. Human blood is employed as a based fluid while magnetite (Fe3O4) and copper (Cu) are taken as the hybrid ferroparticle. The study started with transforming the nonlinear partial differential equation system that governed the model to a more convenience non-linear dimensionless ordinary differential equations using the similarity transformation. The transformed equations obtained then are solved numerically using the Runge-Kutta-Fehlberg (RKF45) method in Maple software. The characteristics and effects of stretching parameter, permeability parameter, thermal radiation parameter as well as the ferroparticle volume fraction in the Williamson hybrid ferrofluid towards the temperature profiles, velocity profiles as well as the Nusselt number and the skin friction coefficient are analysed and discussed. The result of this research for various pertinent parameter varies differently. It can be concluded that the increase in magnetic parameter, the Williamson parameter, the stretching parameter, and the permeability rate parameter increase the skin friction and reduced the velocity profile. Furthermore, the increase in stretching parameter, thermal radiation parameter and the permeability rate results to the increase in the Nusselt number

Effects of Heat Generation/Absorption on a Stagnation Point Flow Past a Stretching Sheet Carbon Nanotube Water-Based Hybrid Nanofluid with Newtonian Heating

This study investigates the mathematical modelling of heat generation/absorption effect on the convective flow of single wall carbon nanotube-copper (SWCNT-Cu)/water hybrid nanofluid towards a stagnation point past a stretching sheet with Newtonian heating. The set of governing equations in the form of non-linear partial differential equations are first transform using the similarity transformation technique then solved numerically by the Runge-Kutta-Fehlberg (RKF45) method in Maple software. The numerical solutions were obtained for the surface temperature, the heat transfer coefficient and the skin friction coefficient as well as the velocity and the temperature profiles. The features of the flow and heat transfer characteristics for various values of the stretching parameter, the conjugate parameter, the nanoparticle volume fraction parameter and the heat source/sink parameter are analyzed and discussed. It is found that effects of hybrid nanoparticles are more significant for lower stretching parameter and for large conjugate parameter values, as well as the heat generation/absorption

MHD Natural Convection Flow of Casson Ferrofluid over a Vertical Truncated Cone

This study considers the mathematical model of MHD free or natural convection boundary layer flow of a Casson ferrofluid over a truncated cone. The set of non-linear partial differential equations that governed the model is first reduced to a simpler set of equations using the non-similar transformation. This set of equations then is solved numerically using the implicit finite difference method known as the Keller-box method. Blood and magnetite are taken as the based-fluid and the ferroparticles for the Casson ferrofluid, respectively. From the numerical study, it was found that the increase of ferroparticles volume fraction results in the increase in the skin friction coefficient and the Nusselt number while the magnetic parameter does the contrary. Further, both parameter shows diminishing effects, whereby if one of the parameter values is set to be increases, the friction between fluid and surface can be controlled by manipulating the other parameter values