TABLE 24 - uploaded by Stefan Cenkowski
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The world produces annually about 2 billion tonnes (Gt) of grains and oilseeds [1] that are handled and stored on-and off-farm for periods of up to 3 years. Often the storage period may be longer than 3 years, for example, when the grain is stored for potential famine relief. To design handling, inspection, and storage systems for grains and oilsee...
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... mass of the grain in the container is meas- ured and the bulk density (kg/m 3 ) or the test weight (kg/hL) is calculated (Canadian Grain Commission [2]). The bulk density for common grains and oilseeds are summarized in Table 24.1 (ASAE [3]). ...
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... ACP measures the true volume of the solid par- ticles. The particle densities of some grains are given in Table 24.2 (ASAE [3]). ...
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... length obta ined by traci ng along the circum ferenc e of the project ed area is defi ned as the perimeter of a kernel. The projecte d area, lengt h, width, an d perim - eter of kernels can be measu red easily using a digit al image process ing system [5] and the values for many seed types are given in Table 24.3. ...
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... ly, the volume occupied by 10 00 ke rnels (random ly selec ted) is measur ed and the average equival ent volume and the diame ter are calculated and report ed (Table 24 .4). ...
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... angles are measured on both sides of the apex and averaged for individual replicates. Typical values of emptying and filling angles of repose of grains and oilseeds are given in Table 24.5. ...
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... measur e the fri ction coeffi- cients agains t vertical walls, a system de scribed by Irvine e t al. [11] can be used. The values of sliding frictio n agains t fou r struc tural mate rials for common grains and oils eeds are given in Table 24.6. ...
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... common method for de termining mois ture co ntent of grains an d oilseeds is to dry samples in triplic ate in a co nvection air oven at a specified tempe ratur e for a specified durati on (Table 24.7; ASAE [12]). Abou t 10-15 g samples a re weighed in covered aluminum dishes . ...
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... EMC-ERH data of grains and oilseeds are ana- lyzed by fitting various equations to the data using nonlinear regression. The commonly used equations are: the modified Henderson, Chung-Pfost, Halsey, Oswin, and Guggenheim-Anderdon-de Boer (G.A.B) (Table 24.8). The modified Henderson [15,16] and modified Chung-Pfost [17,18] equations have been adopted as standard equations by the American So- ciety of Agricultural Engineers for describing EMC- ERH data for cereals and oilseeds. ...
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... of differences in the chemical composition between crops and among cultivars of the same crop, empirical equations have been developed. Usu- ally, these equations describe the relationship between the specific heat and moisture contents of various crops [27,28,33,34,[43][44][45][46][47] (Table 24.11): ...
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... ients a and b for wheat , corn, and grain sor- ghum at various mois ture co ntents an d at 22 8 C have been given by Chang [58]. Also , the therm al con duct- ivity of many grains can be expressed as a linear functio n of mois ture con tent: Table 24.12 gives common relationshi ps for de - terminat ion of the therm al condu ctivity of selected major seed types. ...
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... coeffici ents a an d b for selected seeds have been determ ined and are given in Table 24.14 [66]. ...
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... determini ng the term inal velocity, the drag coeffici ent c an be calcul ated using Equat ion 24.38. The terminal velocity of selec ted seed grains is sum- marized in Table 24.15. The indica ted range reflect s the influence of the geomet ric ch aracteris tics of dif- ferent varietie s and the differen t-sized kernels wi thin the same varie ty. ...
Citations
... According to Fleurat-Lessard (2002), the heat of oxidation of the grain (Q r ) is equal to 15,778 ðJs À1 m À3 Þ. The grain specific heat (c g ) also affects the heat and mass transfer process during aeration (Navarro & Noyes, 2001), and as stated by Lopes et al. (2006), it represents the amount of thermal energy required to increase the temperature of 1 kg of a product by 1 C. Data from Jayas & Cenkowski (2006) was used to determine the grain specific heat ðc g ¼ 1637 Jkg À1 C À1 Þ. ...
The goal of this paper is to present an analytical solution, by means of the method of
manufactured solutions (MMS), for the mathematical model that describes the behaviour
of the grain mass aeration process, proposed by Thorpe. In contrast to related papers in the
literature, several numerical approximations to solve the mathematical model were used.
The finite difference method (FDM), employing the spatial approximations given by the
methods of Roberts and Weiss, Leith, upwind difference scheme (UDS), central difference
scheme (CDS) and UDS with deferred correction (UDS-C), combined with the explicit, implicit
and Crank-Nicolson temporal formulations was applied. The effective order of the
discretisation error achieved with the refinement of the mesh was verified by performing
an error analysis for all approximations used. In addition, the results obtained numerically
were compared to the analytical solution and the CPU (central processing unit) times at
different levels of refinement. The difference in the CPU time using the methods CDS -
Crank-Nicolson, Roberts and Weiss, and Leith, was very small compared to the method
widely used in literature, the UDS - Explicit. It was also verified that the errors obtained by
the proposed methods were considerably smaller than the error obtained by the UDS -
Explicit method. In light of the above, the Leith method is recommended to numerically
solve the grain mass aeration model proposed by Thorpe.
... In addition, the gravimetric properties are presented in Table 3. Due to the larger kernel dimensions, a larger unit mass m was observed compared to values reported by Gürsoy and Güzel [53] and Markowski,Żuk-Gołaszewska and Kwiatkowski [52]. The values of bulk density ρ b0 , solid density ρ s and pore volume ε 0 were found to be in decent agreement with values reported by Molenda and Horabik [48], Haque et al. [23], Jayas and Cenkowski [54], Muir and Sinha [55] and Kraszewski [56]. However, higher values of bulk density ρ b0 and pore volume ε 0 were observed compared to Markowski,Żuk-Gołaszewska and Kwiatkowski [52], which can be ascribed to the cultivar and/or kernel moisture content, as well as container volume, size, quantity of impurities, filling procedure and filling height and rate, which in turn affected the bulk packing in the container [57,58]. ...
Aeration is a key post-harvest grain processing operation that forces air through the pore volume of the grain bulk to establish favorable conditions to maintain grain quality and improve its storability. However, during storage, grain bulk experiences self-compaction due to its dead weight, which alters the bulk properties and impedes the uniform flow of air during aeration. Thus, this study focused on investigating the effect of self-compaction on the pressure drop ΔP of wheat bulk (Triticum aestivum L., cv. ‘Pionier’, X = 0.123 kg·kg−1 d.b.) accommodated in a laboratory-scale bin (Vb = 0.62 m3) at a coherent set of airflow velocities va. Pressure drop ΔP was measured at bulk depths Hb of 1.0, 2.0, 3.0 and 3.4 m and storage times t of 1, 65, 164 and 236 h. For the semi-empirical characterization of the relationship between ΔP and va, the model of Matthies and Petersen was used, which was proficient in describing the experimental data with decent accuracy (R2 = 0.990, RMSE = 68.67 Pa, MAPE = 12.50%). A tailored product factor k was employed for the specific grain bulk conditions. Results revealed a reduction of in-situ pore volume ε from 0.413 to 0.391 at bulk depths Hb of 1.0 to 3.4 m after 1 h storage time t and from 0.391 to 0.370 after 236 h storage time t, respectively. A disproportional increase of the pressure drop ΔP with bulk depth Hb and storage time t was observed, which was ascribed to the irreversible spatio-temporal behavior of self-compaction. The variation of pore volume ε was modeled and facilitated the development of a generalized model for predicting the relationship between ΔP and va. The relative importance of modeling parameters was evaluated by a sensitivity analysis. In conclusion, self-compaction has proven to have a significant effect on airflow resistance, therefore it should be considered in the analysis and modeling of cooling, aeration and low-temperature drying of in-store grain bulks.
... The length, width, and height of seeds were measured by screw gauge according to Digvir and Stefan (2006) whereas the bulk density was determined by the Balasubramanium (1985) followed by Narvani and Panwar (1993). ...
Phytate and tannin are more pronounced antinutrients limiting the nutritional quality of fenugreek. The impact of roasting (130±5°C for 7 minutes), soaking (12 hrs. at room temperature) and germination (72 hrs. at 25°C) on bioactive compounds (polyphenol and antioxidant activity), nutritional and anti-nutritional compounds (phytate and tannin) in Fenugreek were studied. Experimental data were analyzed using the software GenStat 12th Edition. Protein increased significantly (p<0.05) during roasting, soaking, and germination whereas fat decreased significantly. Iron and calcium increased during roasting whereas decreased during soaking and germination. Maximum reduction of phytate (54.55%) and tannin (66.73%) were found when fenugreek seeds were germinated (72 hours). The reduction percentage of antinutrients by soaking (12 hours) and roasting (130±5⁰C for 7 mins) was found to be a lesser effective method compared to germination. All the treatments had a significant (p<0.05) impact on their bioactive components. Phenolic content increased significantly (p<0.05) during roasting, soaking, and germination. Antioxidant activity (IC50=1.28mg dm/ml) was found to be high in the germinated samples as compared to raw, roasted, and soaked samples. Hence, Germination of fenugreek seeds for 72 hours is concluded as the most effective and promising method for the reduction of antinutrients and increasing the nutritional components, phytochemicals, and antioxidant properties.
... Total transmitted heat to the wheat were 1.17 kJ, 2.14 kJ and 3.24 kJ for 65, 90 and 115 � C treatments, respectively. Changes in specific heat of wheat due to different temperature were taken into account (Cao, Li, Zhang, Chen, Li, Zhang, 2010;Jayas & Cenkowski, 2006). ...
Deoxynivalenol (DON) is a mycotoxin produced mainly by Fusarium species and occurs predominantly in cereal grains such as wheat. Due to its toxic effects, in the European Union DON content in unprocessed cereals and processed cereal-based products for human consumption has been regulated, and recommended maximum limits have been established for animal feed. In this study, a method for degrading DON on wheat kernels, by exposition to ammonia (NH3) vapours, was optimized. Results have shown that with a simple treatment with ammonia vapours at 90 °C (for 2 h), degradations higher than 75% were achieved in kernels affected by a moderated contamination up to 2000 μg/kg DON. The study of the reaction between DON and NH3 allowed us to tentatively establish the structure of possible degradation products. In addition, in silico evaluation indicated, in general, lower toxicity and biological effects for the degradation products than for DON.
... where L is the characteristic length (= D p /6), k p is the thermal conductivity of the particle (=0.116 W/m·K for soybean 32 ), K is the apparent first-order rate constant for the pyrolysis reaction which was estimated as a function of temperature by the Arrhenius equation using the activation energy and preexponential factors given by Pyle and Zaror, 31 ρ p is the particle bulk density (=770 kg/m 3 for soybean 33 ), and c p,p is the particle specific heat capacity (=1444 J/kg·K for soybean 34 ). For the reactor temperatures used in this study, values of Bi were estimated to be between 0.5 and 0.7, indicating the presence of moderate internal temperature gradients. ...
In this study, flash pyrolysis was performed using milled soybean as a model substrate to assess the production of liquid fuels from oleaginous biomass feedstocks. A laboratory-scale fluidized-bed flash pyrolysis reactor that allowed rapid heat transfer to the biomass along with short vapor residence time, was designed and constructed. Pyrolysis was performed between 250-610 °C with a vapor residence time between 0.2-0.3 s. At 550 °C or higher, nearly 70 % of the initial feed mass as well as feed carbon was recovered in bio-oil. In addition, 90 % of the feedstock lipids were recovered in the bio-oil at these pyrolysis conditions. The high liquid products yields were attributed to (1) the low secondary degradation of bio-oils due to the short vapor residence time and (2) the high recovery of liquids in a novel dry ice packed-bed condenser that provided a high surface area for condensation/aggregation of dilute bio-oil vapors/aerosols that were entrained in the carrier gas. The bio-oil from this study had higher C- and H- content, higher calorific value and lower oxygen and water content than bio-oil from wood. These results show that high-quality bio-oil at high yield can be obtained from flash pyrolysis of oleaginous feedstock.
... m -3 (ASABE Standards, 2011). Two important parameters for airflow through the wheat media were the permeability and the porosity of the sample; known to be 2.55 × 10 -9 m 2 and 0.4, respectively (Montross and McNeill, 2005;Jayas and Cenkowski, 2006). The properties of air were obtained from the inbuilt material library of COMSOL Multiphysics (Burlington, Mass.). ...
A non-linear model that can explain the three-dimensional airflow pressure patterns in grains was developed and solved using the finite element method. The model can simulate airflow distribution in both flat-bottom and hopperbottom bins of different shapes such as square, rectangular, or cylindrical. Resistance to airflow through the grain bed was explained using a modified form of Darcy's equation. The airflow model was validated against experimental data obtained from studies conducted in a 4.72 m diameter hopper-bottom bin filled with wheat, aerated using a 1.82 m vertical rocket-type aerator. The relative error between the experimental and predicted static pressure values for the entire bin geometry was less than 3.2%, with higher values at regions near the aerator. The validated model can be used to predict the static pressure patterns and airflow distribution (because airflow lines are perpendicular to iso-pressure lines) in various grain beds and can handle variations in product type, moisture content, grain surface configurations, foreign material content, direction of airflow, and aeration duct designs. Using the validated model, airflow pressure patterns in a hopper-bottom cylindrical bin with 10 different duct configurations were predicted and results were discussed for their implications for aeration and near-ambient air drying. The airflow pressure patterns as affected by variations in airflow rate, grain surface configuration (peaked, levelled and conically cored), bin geometry, direction of airflow, and grain bed height (grain filled up to 40%, 60%, and 80% of the bin height) were also simulated and discussed. © 2015 American Society of Agricultural and Biological Engineers.
... The sample was poured onto a horizontal steel plate (30 cm × 35 cm) so that it formed a cone. Using an attached manually driven screw, the inclination of the platform was slowly increased until the sample began to roll down (Jayas and Cenkowski, 2007). The angle of inclination (θ) at this point was determined using the height of the platform from the base and the base length. ...
A discrete phase approach based on individual wheat kernel characteristics is needed to overcome the limitations of previous statistical models and accurately predict the milling behavior of wheat. As a first step to develop a discrete element method (DEM) model for the wheat milling process, this study determined the physical and mechanical properties of wheat mill streams (wheat kernels, break stream, and wheat flour) required as input parameters. The parameters measured were particle size and size distribution, bulk density, Young’s modulus, static and rolling coefficients of friction, and coefficient of restitution. The effect of moisture content (12% to 16% wet basis) on these properties was evaluated. The density, Young’s modulus, and coefficient of restitution tended to decrease while the coefficients of friction tended to increase with increasing moisture content of wheat kernels. The effect of moisture content on material properties was significant for break stream, but there was no significant (p > 0.05) material property change with moisture content for flour. It was concluded that moisture content had a greater significant effect on physical properties (bulk, true, and tapped densities and particle size) of the mill streams than it did on the mechanical properties (Young’s modulus, coefficients of static and rolling friction, and coefficient of restitution)
... The sample was poured onto a horizontal steel plate (30cm x 35cm) so that it formed a cone. Using an attached manually driven screw, the inclination of the platform was slowly increased until the sample began to roll down (Jayas and Cenkowski, 2007). ...
... The first five models are empirical and predict the equilibrium moisture content (M) as a function of temperature and relative humidity. The GAB equation, on the other hand, is a three parameter, semi-theoretical model that does not incorporate the effect of temperature in predicting M (Jayas and Cenkowski 2006). The Henderson and Chung-Pfost models have been used to predict the M of various grains and seeds (Stroshine 1998) and selected starches (Boki and Ono 1991) while the modified Oswin model adequately described the moisture sorption behavior of wheat (Sun and Woods 1994) and chickpea flour (Durakova et al. 2005). ...
The proximate composition and the effect of moisture content on particle size and particle distribution, bulk and particle densities, color, flow properties, compression characteristics, moisture sorption behavior, and frictional properties of plant-sourced wheat distillers dried grains with solubles (DDGS) were assessed. Proximate composition significantly differed between samples obtained from two production batches. Protein content of wheat DDGS was higher while its fat content was lower compared to published corn DDGS values. Most of the physical properties were significantly affected by moisture content. Under the Carr classification system, plant-sourced wheat DDGS was considered as fairly flowable and floodable and may require measures to assure flow and prevent flushing. The Kawakita-Ludde and Guggenheim, Anderson and De Boer (GAB) models adequately described its compression characteristics and moisture sorption behavior, respectively.
... The measurement methods of various quality degrading factors have been standardized and adopted by several countries (CGC, 1993;Jayas and Cenkowski, 2006). With the advancement in new technologies, researchers have been trying to use different equipment for effectively measuring the grain quality parameters. ...
In most years and in most countries grain is dried to safe storage moisture content using different drying systems, i.e. natural air drying, near-ambient (low temperature) drying, high temperature drying, and dryeration. During natural air and near ambient drying detrimental effects on grain quality can be avoided if drying can be completed within the allowable safe storage time which depends on the initial moisture content of grain and weather conditions. During high temperature drying detrimental effects on grain quality can be avoided if grain is not heated beyond critical temperature. If grain is heated beyond critical temperature due to dryer type or improper functioning of dryer then end use characteristics of grain can be severely affected. Dryeration combines high temperature drying with low temperature cooling and results in better quality grain than high temperature drying for the removal of the same amount of moisture. Further research is needed to develop effective control strategies to optimize dryers for grain quality, uniformity of drying, and energy efficiency. Research is also needed to develop dryers which operate quietly, discharge less pollutants, and are economic.
