FEDSM2006-98420 TWO-DIMENSIONAL IMAGING OF SOOT VOLUME FRACTION IN PULSED DIFFUSION FLAMES BY LASER-INDUCED INCANDESCENCE

ABSTRACT Laser-Induced Incandescence (LII) is used in this study to measure soot volume fractions in steady and flickering ethylene diffusion flames burning at atmospheric pressure. Better understanding of flickering flame behavior also promises to improve understanding of turbulent combustion systems. A very-high-speed solenoid valve is used to force the fuel flow rate with frequencies between 10 Hz and 200 Hz with the same mean fuel flow rate of steady flame. Periodic flame flickers are captured by two-dimensional phase-locked emission and LII images for eight phases (0° -360°) covering each period. LII spectra scan for minimizing C 2 swan band emission and broadband molecular florescence, a calibration procedure using extinction measurements, and corrections for laser extinction and LII signal trapping are carried out towards developing reliable LII for quantitative applications. A comparison between the steady and pulsed flames results and the effect of the oscillation frequency on soot volume fraction for the pulsed flames are presented

Comparison of energy storage options and detrmination of suitable technique for solar power systems

Paper presented to the 3rd Southern African Solar Energy Conference, South Africa, 11-13 May, 2015.The efficiency and cost of renewable solar and wind power systems using intermittent resources could significantly be improved by developing low cost, high efficiency and more sustainable energy storage systems. A comparison study between energy storage options is presented in this paper. The energy storage options include: (1) electro chemical storage: lead acid, Li-ions, Nickel-Cadmium, Nickel metal hydride, Sodium Sulfur, and vanadium flow batteries; (2) electro-magnetic energy storage: super capacitors and super conducting magnetic energy storage; (3) hydrogen storage: onboard systems and utility scale; (4) mechanical storage: compressed air, flywheel, pumped hydro, spring (composite and metal), and (5) thermal energy storage. The resource intensities and operational parameters of the energy storage options are compared in this study. The main objective is to review the various types of storage techniques and their characteristics and to determine the most appropriate technique for solar and wind energy applications: energy storage system with suitable discharge time, lowest resource intensities, best operation performance and lowest cost. Based on the results obtained in this study, super capacitors, super conducting magnetic, and flywheel energy storage systems could be a good option for solar and wind applications: they offer fast discharging/charging times, greater performance (high specific power, high cycle efficiency, high cycle life and they) and are very attractive with respect to the operating costs.dc201

New correlations for the average Nusselt number in squealer turbine blade tip

Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.Numerical simulations of the flow field and heat transfer of squealer blade tip are performed in this study. The effects of the Reynolds number, the clearance gap to width ratios (C/W = 5% -15%) and the cavity depth to width ratios (D/W = 10%-50%) on fluid flow and heat transfer characteristics are obtained. The temperature and velocity distributions inside the cavity, the local heat transfer coefficients, and the average Nusselt numbers for the pressure and suction sides of the turbine blade tip are determined. This paper presents the results of the effects of Reynolds number, clearance gap and width ratios on the Nusslet number for the pressure and suction sides of squealer turbine blade tip. The results show a good agreement with the experimental data obtained by Metzger and Bunker. New correlations for the average Nusselt numbers for turbine blade tip pressure and suction sides are presented.cf201

Numerical simulation of internal channel cooling via jet impingement in fluent and its sensitivity study

Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.Impinging jets against surface provide effective heat transfer in various industrial applications. It includes vast applications such as gas turbine cooling, rocket launcher cooling, heat treatment, cooling of electronic components, heating of optical surfaces for defogging, cooling of turbine components, cooling of critical machinery structures, and many other industrial processes. In this work, the numerical analysis of various heat transfer configurations of jet impingement on a semi-circular surface was studied. These heat transfer configurations were compared on the basis of effective heat transfer by achieving higher Nusselt number as convection is becoming the dominant phenomenon. The internal channel, on which analysis is performed, is a curved surface with a uniform heat flux. The numerical result obtained is favorably comparable with the experiment results. Furthermore, sensitivity study for various materials, configuration (geometry) and conditions was carried out to gain more insight on the underlining physics of the flow. Finally, the favorable application of inner cooling to turbine blade is numerically demonstrated.dc201

Assessment of glycerol gasification: devolatilization kinetics and parametric analysis

The forecasted need for diesel fuel continues to rise, and likewise the competitive biodiesel demand in the middle to long term future remains promising. Unfortunately, biodiesel production generates a significant amount of crude glycerol with the byproduct typically exceeding 10% of the biodiesel produced. The current glycerol market cannot accommodate the use of waste crude glycerol; therefore, an alternative solution is needed for the utilization of the crude glycerol and gasification is a potential pathway. In this work, the technical feasibility of gasification of crude glycerol is assessed at two levels, equilibrium modeling which was conducted under ideal conditions, and high-fidelity reactive flow modeling in a tubular reactor. Results revealed that elevated steam ratios are required for the gasification of glycerol to reach high conversion rates of 99% and an acceptable cold gasification efficiency of 40%. Although this value is far off from the conventional coal gasification that hovers around 60%, the anlysis suggests that gasification of crude glycerol can be accepted as an intermediate solution to the expected flood of glycerol generated by the biodiesel transesterification industry before becoming a waste burden

IMECE2004-61743 EFFECT OF BOUNDARY CONDITIONS AND INITIAL CONCENTARTIONS ON THE SOLIDFICATION OF BINARY MIXTURE IN TRAPEZOIDAL CAVITY

ABSTRACT The solidification of binary mixture (NH 4 Cl-H 2 O) inside a trapezoidal cavity is investigated experimentally in this study. The experiments are carried out in a trapezoidal cavity measuring 65 mm x 130 mm x 150 mm with inclined angle of 69 0 . Solidification of ammonium chloride occurs on the left inclined copper wall held under constant heat rate condition while the other walls are maintained at adiabatic conditions. Particle image velocimetry was used in this study for visualization of the dynamic field during the solidification process. The temperatures of the solution inside the cavity and the boundary walls were measured by 32 thermocouples during the solidification process. Convective flow field, temperature distribution and frozen layer thickness were obtained for different initial concentrations of ammonium chloride varying from 0 to 19.8 % (sub-eutectic and near-eutectic growth) and various boundary conditions (T cold = -30 0 C to 0 0 C). The results obtained in the course of study reveal that (1) the solidification rate is higher during initial stages of the solidification process, (2) the process of solidification is slower with increase in the initial concentration levels of the ammonium chloride and (3) the initial concentration play a significant role in the evolution of convection flow patterns

Heat integration modeling of hydrogen production from date seeds via steam gasification

The purpose of the current study is to identify the potential of energy-efficient hydrogen (H2) production from date seeds as biomass via steam gasification process along with heat integration in Gulf countries. A reaction kinetics model has been established for steam gasification with in-situ carbon dioxide (CO2) capture of date seeds using MATLAB software. The kinetics of reactions involved in the gasification process was calculated using the optimization parameters fitting approach. The heat integration model has been developed via mixed integer nonlinear programming (MINLP) in MATLAB. In the parametric study, temperature and steam/biomass ratio considered their impact on syngas composition and energy recovery. Results showed that both variables have a strong positive effect on H2 production and depicted maximum production of 68 mol% at a temperature of 750 °C with steam/biomass ratio of 1.2. Methane (CH4) and CO2 production were low in the product gas, which showed the activity of water gas shift reaction, methanation reaction, and carbonation reaction. Utilization of waste heat via process heat integration within the system reduced system's external heat load. More than 70% of energy recovered, which could be utilized for gasification and steam production. Energy analysis and process heat integration proved a prospective approach for energy-efficient and sustainable hydrogen production from date seeds