Abstract-Mass losses of Phoenix dactylifera date palm seeds (DPSs) were measured using a thermo-gravimetric analyzer (TGA). Six-milligram-sample of six varieties of DPSs were pyrolyzed in an inert condition (argon atmosphere) with a constant flow rate of 100 ml/min for the entire range of experiments. The experiments were conducted under non-isothermal conditions and at a heating rate of 20°C/min until the furnace wall temperature reached 900°C. The moisture (M), ash (ASH), volatile matter (VM) and fixed carbon (FC) of the selected date seeds were determined by means of proximate analysis. The weight percentages of carbon (C), hydrogen (H), oxygen (O), nitrogen (N), sulfur (S) and atomic ratios (H/C and O/C) were determined through the ultimate analysis. The heating value, bulk and particle density of DPSs were also measured using a bomb calorimeter and ultra-pycnometer, respectively. The yield of the liquids was obtained by subtracting the total gaseous mass from the DTG data. The experiments demonstrated that there were significant differences in physiochemical properties of selected DPSs. The findings also revealed that DPSs contain much volatile compounds. DPSs energy densities were found to be among the high-quality biological feedstocks.Index Terms-Date palm seeds, pyrolysis, TGA, thermal characteristic.
Proper orthogonal decomposition (POD) is a coherent structure identification technique based on either measured or computed data sets. Recently, POD has been adopted for the analysis of the in-cylinder flows inside internal combustion engines. In this study, stereoscopic particle image velocimetry (Stereo-PIV) measurements were carried out at the central vertical tumble plane inside an engine cylinder to acquire the velocity vector fields for the in-cylinder flow under different experimental conditions. Afterwards, the POD analysis were performed firstly on synthetic velocity vector fields with known characteristics in order to extract some fundamental properties of the POD technique. These data were used to reveal how the physical properties of coherent structures were captured and distributed among the POD modes, in addition to illustrate the difference between subtracting and non-subtracting the ensemble average prior to conducting POD on datasets. Moreover, two case studies for the in-cylinder flow at different valve lifts and different pressure differences across the air intake valves were presented and discussed as the effect of both valve lifts and pressure difference have not been investigated before using phase-invariant POD analysis. The results demonstrated that for repeatable flow pattern, only the first mode was sufficient to reconstruct the physical properties of the flow. Furthermore, POD analysis confirmed the negligible effect of pressure difference and subsequently the effect of engine speed on flow structures.
Abstract. The pyrolytic behavior of evolved gases from date palm seeds (DPSs) were measured to gain insight into the mechanism of DPSs pyrolysis. Six different cultivars were used in this study, namely Deglet nour, Piarom, Suffry, Safawi, Mabroom and Aliya. A thermo-gravimetric analyzer (TGA) and a real-time gas analyzer (GA) were used to calculate the mass losses and the mole fraction of evolved gases, respectively. DPSs samples were pyrolyzed in an inert atmosphere condition using argon with a purge rate of 100 mL/minute. The samples were subjected to non-isothermal operation. An independent single model and parallel reaction model were adopted to interpret the empirical data collected from TGA and GA, respectively. The results reveled that there are three types of pyrolysis zones depending on the main constituents of every cultivars. Moreover, the potentialty of the zones in controlling the pyrolysis behavior was noticeable. The dominant hydrocarbon species in DPSs were CO and CH4 (40 to 50% higher than the rest of species). The mole fraction of CO was 2 to 4 times higher than the mole fraction of CO2. The activation energy and frequency factor of DPSs evolved species showed that Mabroom has the highest activation energy regarding H2 (63.21kJ/mol) and CO (74.32 kJ/mol).
To predict the performance of a fluidized bed gasifier (FBG) using date palm seeds (DPSs) as feedstock, a two-phase model was developed. The model simulates the hydrodynamic, kinetic reaction and steady state operations using the Aspen plus software. Experimental works were performed to study the effect of bed temperature, steam to biomass ratio, gas yield and carbon conversion efficiency. Six varieties of date palm seeds were studied: Deglet Nour (DN), Piarom (PI), Safawi (SA), Mabroom (MA), Suffry (SU), and Aliya (AL). The experimental data was used to validate the prediction model. Materials, process energy balances along with the minimization of free energy method were considered to measure the gas mole fraction. Different reactors of Aspen simulator, namely RYield, RGibbs and RCSTR plus MATLAB models were used to investigate the behaviour of DPSs in the FBG. The results confirmed that there were significant differences between all DPS varieties and treatments. The simulated results showed a good agreement with the experimental data. The gas yield (13.4% increase), lower heating value (11.9% increase), carbon conversion efficiency (9.7% increase and steam decomposition (17% increase) improved considerably with the rise of temperature from 730°C to 800°C. Higher temperatures under steam gasification boosted the overall efficiency of the gasification process. H2 and CO production increased by as much as 35% and 29% (by volume) respectively at 800°C. CH4 contributed to the total yield of gas by a maximum of 13% and 15% for experimental and simulation works, respectively. CO2, on the other hand, showed a tendency to react positively (more than 50% of the total gas yield) at higher temperatures in both experimental and simulation studies.
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