Varying Bulk Densities Research Articles

Advanced fabrication of lignin-formaldehyde resin derived carbon microspheres via spray drying

Carbon hollow microspheres (CHM) have been heralded as a seminal material, manifesting a multifaceted utility in domains such as catalysis, adsorption, energy storage, and conversion. In this study, the present investigation delves into the fabrication of lignin-formaldehyde resin (LFR) carbon hollow microspheres (LFR-CHM) via the nuanced methodologies of spray drying and subsequent carbonization. The precursor for CHM, a thermosetting LFR, was crafted via polycondensation in an alkaline milieu. Precision-tuning of the spray drying parameters enabled the realization of LFR hollow microspheres, characterized by particle diameters spanning 3.37 μm–24.4 μm, and shell thickness between 0.25 μm and 4.0 μm. Adjusting the inlet temperature from 110 to 180 °C resulted in LFR hollow microspheres with varying bulk densities from 0.31 g/cm3 to 0.49 g/cm3. The microporous structure of the LFR-CHM shell exhibited a malleable specific area and pore dimensionality, intricately tethered to the carbonization thermal gradient. Furthermore, changes in crystallinity and chemical bonds of LFR-CHM were noted during carbonization process. Significantly, the residual weight of LFR-CHM reached 52 % after carbonization at 800 °C, underscoring the benefits of using thermosetting lignin-formaldehyde resin as a CHM precursor.

Effect of gravel content on soil water retention characteristics and thermal capacity of sandy and silty soils

Abstract The presence of gravel in soils modifies the porosity, pore connectivity and pore size distribution in the soil matrix as well as the soil matrix-gravel interfaces. The aim of the present study is to investigate the effect of relative volume of gravel in samples with gravel mass fractions of 5,10, 20 wt% and varying bulk densities (1.3, 1.45, 1.55, 1.60, 1.65 g cm–3) on (i) total porosity, field capacity, plant available water holding capacity, (ii) pore size distribution and (iii) thermal capacity of repacked sandy and silty soils. The focus of the study was to determine if laboratory measured soil water retention curves considering (i), (ii), and (iii) can be predicted by a gravel-based weighting factor, Rv, considering comprehensive significance tests. The sand-gravel mixtures show a decrease in the volume fractions of macropores and wide cores pores with an increase in the gravel contents, while the silt-gravel mixtures show an opposite trend. The root mean square errors (RMSE) between measured and fitted volumetric water contents, θ, between 0.006 and 0.0352 and between 0.002 and 0.004 for Rv-weighted volumetric water contents indicate that the van Genuchten-based Peters-Durner-Iden (PDI) model is appropriate for fitting. The soil water retention curves with mass gravel contents of up to 10 wt% for silt and 20 wt% for sand can be well predicted by weighting factors (relative volume of rock fragments) in the range between 0.045 and 0.058 for silt, and between 0.112 and 0.119 for sand. The results also indicate a decrease in the Rv-weighted saturated, cvsat, and dry, cvdry, thermal capacity with an increase in the gravel contents for both soils. Further investigations are needed to examine if and whether measured sand- and silt-gravel mixtures with mass gravel contents below 10 % or rather 20 % can be predicted with a weighting factor.

Thermal Diffusivity of Concrete Samples Assessment Using a Solar Simulator.

The thermal properties of pavement layers made of concrete with varying bulk densities are a particularly interesting topic in the context of development road technologies. If a hybrid layer system is used as a starting point, with thin asphalt layers (from 1 cm to 4 cm) laid on top of a foam concrete layer, thermal properties begin to play a crucial role. The main research problem was to create a test method enabling the assessment of the influence of solar heating on the thermal parameters of the building material, especially cement concrete. For this reason, this paper is concerned specifically with the assessment of a new methodology for testing and calculating the value of the thermal diffusivity coefficient of samples made of concrete varying bulk densities. In this case, using the proprietary concept the authors built a solar simulator using a multi-source lighting system. The analysis of the results of laboratory tests and numerical analyses allowed the authors to observe that there is a strong correlation between the bulk density of samples heated and the thermal diffusivity parameter, which appears in the unidirectional heat transfer equation. The strength of this relationship has been expressed with the coefficient of determination and amounts to 99%. The calculated values of the coefficient of thermal diffusivity for samples made of foam concrete range from 0.16×10-6m2s to 0.52×10-6m2s and are lower (from 2.5 to 8 times) than the value determined for samples made of typical cement concrete.

Measurement methods for quantifying powder flowability and velocity in cold spray systems

Four powders with varying bulk densities, Al, Al2O3, Sn, and Cu, were used to determine quantifiable relationships between powder flowability, mass flow rate, and powder velocity with particle morphology and particle distribution in a cold spray system. High particle density results in good powder flowability, specifically when the powders are spherical relative to irregular morphology. Particle velocity during cold spray, measured with a double disk rotary system, increases non-linearly with an increase of inlet pressure. The increase in mass flow rate from the hopper and the resulting mass output of the cold spray system shows a consequence of good powder flowability. Conversely, a high mass flow rate decreases the particle velocity during the cold spray process, with better flowability leading to decreases on the order of 10% in particle velocity in the cold spray system. The described methods, proposed tools, and findings can be easily made with cost-effective and on-the-spot measurements.

Effects of petroleum hydrocarbon concentration and bulk density on the hydraulic properties of lean oil sand overburden

In the Alberta oil sands, sand containing less than 8% petroleum hydrocarbon (PHC) is referred to as lean oil sand (LOS) and is used as subsoil in reclamation. The objective of this study was to determine how bulk density and PHC concentration affect the hydraulic properties of LOS. The LOS was packed in soil cores at varying bulk densities and PHC concentrations, representing the range in these parameters that occur in the reclamation setting. The cores were placed on a tension table and pressure plates to measure water retention. The constant head method was used to measure the saturated hydraulic conductivity (Ks) of the LOS. Results show that increasing PHC concentration reduced the water retention of LOS due to the presence of PHCs in soil micropores. PHC concentration also had a significant effect on the van Genuchten curve fitting parameters for the water retention curve, although the shape of the curves remained similar regardless of PHC content. Furthermore, there is a significant reduction in Ks at the high bulk density and high PHC concentrations (3.25%–7.48%), compared with low PHC concentrations (0%–1.63%). Due to the reduced Ks with increased PHCs and bulk density, LOS used as the base material in reclamation will reduce percolation and increase water storage in the reclamation soil cover.

Assessment of Low-Volatile Poor Caking Indian Coal for Coke Making

ABSTRACTCoal is the most abundant source of global energy. Due to limited reserves of coking coal, low-grade coals particularly low-volatile poor caking coals in India contributing significantly to the total reserves need to be utilized to meet the requirement of coking coal. But these coals have not yet fully secured their access in iron and steel industries. Studies were carried out on low-volatile poor-caking coal for evaluating its potential for coke making though washing and stamping at varying bulk densities in the presence of moisture as binder at lower temperature for a shorter duration. The coal had poor washability characteristics. Washed coal in stamp charging showed improvement in its coke characteristics mostly to the level of requirements for metallurgical coke of India and abroad. For plant-scale blast furnace coke making, blending the washed coal with appropriate proportion of high-volatile good coking coal may ensure its suitability.

Engineering and functional properties of biodegradable pellets developed from various agro-industrial wastes using extrusion technology.

Different agro-industrial wastes were mixed with different plasticizers and extruded to form the pellets to be used further for development of biodegradable molded pots. Bulk density and macro-porosity are the important engineering properties used to determine the functional characteristics of the biodegradable pellets viz., expansion volume, water solubility, product colour, flowability and compactness. Significant differences in the functional properties of pellets with varying bulk densities (loose and tapped) and macro-porosities (loose, tapped) were observed. The observed mean bulk density of biodegradable pellets made from different formulations ranged between 0.213 and 0.560g/ml for loose fill conditions and 0.248 to 0.604g/ml for tapped fill conditions. Biodegradable pellets bear a good compaction for both loose and tapped fill methods. The mean macro-porosity of biodegradable pellets ranged between 1.19 and 54.48% for loose fill condition and 0.29 to 53.35% for tapped fill condition. Hausner ratio (HR) for biodegradable pellets varied from 1.026 to 1.328, indicating a good flowability of biodegradable pellets. Pearson's correlation between engineering properties and functional properties of biodegradable pellets revealed that from engineering properties functional properties can be predicted.

Effects of bulk density of steam-flaked corn in diets containing wet corn gluten feed on feedlot cattle performance, carcass characteristics, apparent total tract digestibility, and ruminal fermentation1

The effects of varying bulk density of steam-flaked corn (SFC) in diets containing wet corn gluten feed (WCGF; Sweet Bran; Cargill Corn Milling, Blair, NE) have not been defined. In Exp. 1, yearling steers (n = 108; initial BW = 367 ± 1.18 kg) were housed in 27 pens (4 steers/pen) and received 1 of 3 different SFC bulk density treatments in a randomized complete block design. Bulk density treatments were 283, 335, or 386 g/L SFC in diets containing 25% WCGF (% of DM). Steers were fed once daily to provide ad libitum access to feed for an average of 163 d. For a 5-d period before d 70 of the experiment, DMI was measured, and fecal samples were collected from each pen for measurement of nutrient digestibility using dietary acid insoluble ash as a marker. Varying bulk densities of SFC did not affect (P ≥ 0.233) overall DMI, ADG, or G:F on a live- or carcass-adjusted basis. Dressing percent and LM area increased linearly (P ≤ 0.05) as bulk density increased, but other carcass traits were not affected by treatments. Intake of DM, OM, and CP during the 5-d digestion phase did not differ among bulk densities; however, starch intake increased linearly (P = 0.004) as bulk density of SFC increased. Digestibility of DM, OM, and CP tended (P ≤ 0.065) to decrease and starch digestibility decreased (P = 0.002) linearly as bulk density of SFC increased. In Exp. 2, a 3 × 3 Latin square design was used for collection of ruminal fluid from 3 ruminally cannulated Jersey steers adapted to the same diets used in Exp. 1. Bulk density did not affect NH3 concentrations, VFA molar proportions, ruminal fluid osmolality, and IVDMD of the diets. Total gas production increased linearly (P = 0.003) as bulk density of SFC increased from 283 to 335 g/L, but it decreased (P = 0.002) at 386 g/L. Present data suggest that bulk density can be increased up to 386 g/L in finishing diets containing 25% (DM basis) WCGF without affecting cattle performance and with limited effects on ruminal fermentation; however, digestibility of starch seemed to be affected negatively by increased bulk density in these diets.

Soil Moisture Sensing via Swept Frequency Based Microwave Sensors

There is a need for low-cost, high-accuracy measurement of water content in various materials. This study assesses the performance of a new microwave swept frequency domain instrument (SFI) that has promise to provide a low-cost, high-accuracy alternative to the traditional and more expensive time domain reflectometry (TDR). The technique obtains permittivity measurements of soils in the frequency domain utilizing a through transmission configuration, transmissometry, which provides a frequency domain transmissometry measurement (FDT). The measurement is comparable to time domain transmissometry (TDT) with the added advantage of also being able to separately quantify the real and imaginary portions of the complex permittivity so that the measured bulk permittivity is more accurate that the measurement TDR provides where the apparent permittivity is impacted by the signal loss, which can be significant in heavier soils. The experimental SFI was compared with a high-end 12 GHz TDR/TDT system across a range of soils at varying soil water contents and densities. As propagation delay is the fundamental measurement of interest to the well-established TDR or TDT technique; the first set of tests utilized precision propagation delay lines to test the accuracy of the SFI instrument’s ability to resolve propagation delays across the expected range of delays that a soil probe would present when subjected to the expected range of soil types and soil moisture typical to an agronomic cropping system. The results of the precision-delay line testing suggests the instrument is capable of predicting propagation delays with a RMSE of +/−105 ps across the range of delays ranging from 0 to 12,000 ps with a coefficient of determination of r2 = 0.998. The second phase of tests noted the rich history of TDR for prediction of soil moisture and leveraged this history by utilizing TDT measured with a high-end Hewlett Packard TDR/TDT instrument to directly benchmark the SFI instrument over a range of soil types, at varying levels of moisture. This testing protocol was developed to provide the best possible comparison between SFI to TDT than would otherwise be possible by using soil moisture as the bench mark, due to variations in soil density between soil water content levels which are known to impact the calibration between TDR’s estimate of soil water content from the measured propagation delay which is converted to an apparent permittivity measurement. This experimental decision, to compare propagation delay of TDT to FDT, effectively removes the errors due to variations in packing density from the evaluation and provides a direct comparison between the SFI instrument and the time domain technique of TDT. The tests utilized three soils (a sand, an Acuff loam and an Olton clay-loam) that were packed to varying bulk densities and prepared to provide a range of water contents and electrical conductivities by which to compare the performance of the SFI technology to TDT measurements of propagation delay. For each sample tested, the SFI instrument and the TDT both performed the measurements on the exact same probe, thereby both instruments were measuring the exact same soil/soil-probe response to ensure the most accurate means to compare the SFI instrument to a high-end TDT instrument. Test results provided an estimated instrumental accuracy for the SFI of +/−0.98% of full scale, RMSE basis, for the precision delay lines and +/−1.32% when the SFI was evaluated on loam and clay loam soils, in comparison to TDT as the bench-mark. Results from both experiments provide evidence that the low-cost SFI approach is a viable alternative to conventional TDR/TDT for high accuracy applications.

Volumetric hydrogen sorption capacity of monoliths prepared by mechanical densification of MOF-177

Bulk powdered MOF-177 is mechanically compressed to prepare monoliths with bulk densities more than three times its crystallographic density, and their excess and total gravimetric and volumetric hydrogen storage capacities are measured over a pressure range of 0–13 MPa at 77 K and room temperature. The maximum excess volumetric hydrogen storage capacity of these monoliths at ∼6 MPa and 77 K is 25.8 ± 1.2 g L−1, which is a 78% increase of that of powdered bulk MOF-177 and 80% of the theoretical maximum excess volumetric hydrogen storage capacity predicted on the basis of the material's crystallographic density. The monoliths show diminishing excess gravimetric capacity with increasing density which is attributed to their decreasing micropore volume, which in turn stems from the progressive collapse of MOF-177 crystals to an amorphous phase when they are subjected to densification. A modified Dubinin–Astakhov (DA) model is adapted to describe the excess gravimetric adsorption of samples with varying bulk densities. The total volumetric capacity of monoliths prepared from MOF-177 is 48.0 ± 2.1 g L−1 at 13 MPa and 77 K; if a complete storage system that does not reduce this capacity by more than 20% is designed, it can then meet the DOE 2015 volumetric system target at 77 K. Under the same conditions, it is easier to meet the DOE 2015 gravimetric system target of 5.5 wt% as the material's total gravimetric storage capacity is ∼10.3 ± 0.3 wt%.

Effects of varying bulk densities of steam-flaked corn and dietary roughage concentration on in vitro fermentation, performance, carcass quality, and acid-base balance measurements in finishing steers1

Effects of varying bulk densities of steam-flaked corn (SFC) and level of inclusion of roughage in feedlot diets were evaluated in 3 experiments. In Exp. 1, a total of 128 beef steers were used in a 2 x 2 factorial arrangement to evaluate the effects of bulk density of SFC (335 or 386 g/L) and roughage concentration (6 or 10% ground alfalfa hay, DM basis) on performance and carcass characteristics. No interactions were observed between bulk density and roughage concentration for performance data. From d 0 to the end, cattle fed the 335 g/L SFC had greater overall G:F (P = 0.04) than those fed the 386 g/L SFC, with tendencies (P < 0.10) for improved G:F with the lighter flake weight evident at all 35-d intervals throughout the feeding period. Dry matter intake was less for cattle fed 6 vs. 10% roughage from d 0 to 35 (P = 0.03) and d 0 to 70 (P = 0.05), but not for the overall feeding period. Feeding 6 vs. 10% ground alfalfa as the roughage source tended (P = 0.09) to improve overall G:F. Treatment effects on carcass measurements were generally not significant (P > 0.20). In Exp. 2, the effects of bulk density of SFC (283, 335, or 386 g/L) and 6 or 10% ground alfalfa hay on IVDMD and in vitro pH were evaluated at 6, 12, 18, and 24 h of incubation. With a reduced-strength buffer in vitro fermentation system, pH increased (P < 0.01) with increasing bulk density at 6 and 12 h, and IVDMD decreased (P < 0.03) as bulk density increased. In contrast, in a normal-strength buffer system, there were no treatment differences (P > 0.23) for IVDMD. In Exp. 3, two diets that varied in bulk density of SFC and roughage concentration (335 g/L SFC with 6% alfalfa hay vs. 386 g/L SFC with 10% alfalfa hay) were compared for their effects on the pattern of feed intake and the acid-base balance in Holstein steers (12/treatment). No differences (P > 0.10) between treatments were noted for blood gases or urine pH; however, day effects (P < 0.02) were detected for blood pH, partial pressure of CO(2), and urine pH, which generally decreased (P < 0.05) with an increasing time on feed. The 2 treatments had little effect on the pattern of feed intake within the sampling days, with the exception that the 386 g/L SFC with 10% alfalfa hay diet increased (P < 0.05) the percentage of total DMI consumed at 1 and 6 h after feeding on d 14. Within the ranges of bulk density and roughage level studied, 335 g/L SFC with 6% alfalfa hay yielded the optimal animal performance, with limited effects on in vitro fermentation and the acid-base balance.

Determination of thermal properties of composting bulking materials

Thermal properties of compost bulking materials affect temperature and biodegradation during the composting process. Well determined thermal properties of compost feedstocks will therefore contribute to practical thermodynamic approaches. Thermal conductivity, thermal diffusivity, and volumetric heat capacity of 12 compost bulking materials were determined in this study. Thermal properties were determined at varying bulk densities (1, 1.3, 1.7, 2.5, and 5 times uncompacted bulk density), particle sizes (ground and bulk), and water contents (0, 20, 50, 80% of water holding capacity and saturated condition). For the water content at 80% of water holding capacity, saw dust, soil compost blend, beef manure, and turkey litter showed the highest thermal conductivity ( K) and volumetric heat capacity ( C) ( K: 0.12–0.81 W/m °C and C: 1.36–4.08 MJ/m 3 °C). Silage showed medium values at the same water content ( K: 0.09–0.47 W/m °C and C: 0.93–3.09 MJ/m 3 °C). Wheat straw, oat straw, soybean straw, cornstalks, alfalfa hay, and wood shavings produced the lowest K and C values ( K: 0.03–0.30 W/m °C and C: 0.26–3.45 MJ/m 3 °C). Thermal conductivity and volumetric heat capacity showed a linear relationship with moisture content and bulk density, while thermal diffusivity showed a nonlinear relationship. Since the water, air, and solid materials have their own specific thermal property values, thermal properties of compost bulking materials vary with the rate of those three components by changing water content, bulk density, and particle size. The degree of saturation was used to represent the interaction between volumes of water, air, and solids under the various combinations of moisture content, bulk density, and particle size. The first order regression models developed in this paper represent the relationship between degree of saturation and volumetric heat capacity ( r = 0.95–0.99) and thermal conductivity ( r = 0.84–0.99) well. Improved knowledge of the thermal properties of compost bulking materials can contribute to improved thermodynamic modeling and heat management of composting processes.

Effects of compact layer on salt accumulation in plastic film house soils

A compact layer was detected below the plow layer of old plastic film house soils (Eutrudepts) cultivated for more than 10 y in Yousung and Yesan districts, in the central part of Korea. In addition, salts had accumulated in the surface layers of these soils. One representative site was irrigated continuously for 96 h and redistribution patterns of the salts and water were investigated. Initially, the salt concentration was highest in the uppermost soil layer and decreased with increasing depth, due to the high evaporation rates inside the plastic film house. Continuous irrigation moved the peak point of electrical conductivity (EC) and the wetting point to a 20-30 cm depth after 48 h. Additional irrigation (96 h) did not move significantly the EC peak point or change the water regime. In order to analyze the effects of the compact layer on the inhibition of water flow and salt movements in the soil profile, saturated hydraulic conductivity (K sat) and salt elution time were determined in soil columns with varying bulk densities. K sat significantly decreased with increasing soil bulk density up to 1.4 Mg m-3. Salt elution time was markedly delayed by about 100 h when the K sat rate at a 10 em depth of the soil profile in a 1.4 Mg m-3 soil column was compared with that in a 1.3 Mg m-3 soil column. The point of zero net charge (PZNC) was used to monitor the effects of soil charge characteristics on the retardation of salt elution. PZNC was observed at lower pH values than the intrinsic pH of the Ap and Bw horizons. It was expected that anions with non-specific adsorption properties would be scarcely adsorbed. In batch tests, the soil materials in the Ap and Bw horizons only slightly adsorbed 3 anions (NO3 -, CI-, and SO4 2-). As a result, the compact layer was the most important factor in accelerating salt accumulation in the surface soil of old plastic film houses. Chemical reactions had a limited or minor impact on the salt movement and salt infiltration in the soil profile. It is considered that it may be difficult to effectively improve old plastic film house soils with salt accumulation without reclaiming the compact layer.

Determining moisture content of wheat with an artificial neural network from microwave transmission measurements

An artificial neural network (ANN) was used to determine the moisture content of hard, red winter wheat. The ANN was trained to recognize moisture content in the range from 10.6% to 19.2% (wet basis) from transmission coefficient measurements on samples of wheat. The measurements were made at 8 microwave frequencies (10 GHz to 18 GHz) on wheat samples of varying bulk densities (0.72 g/cm/sup 3/ to 0.88 g/cm/sup 3/) at 24/spl deg/C. The trained network predicted moisture content (%) with a mean absolute error of 0.135 (compared with oven-dried measurements).

Does the uniform packing of sand in a cylinder provide a uniform penetration resistance

Sand packed to a constant dry bulk density, is frequently used as an artificial growth medium in which to simulate the effects of a constant mechanical impedance on root growth. This research aimed to determine whether conventional packing resulted in constant mechanical impedance and to test alternative packing regimes. Perspex cylinders 300 mm tall with a 49 mm internal diameter were packed with moist sand to uniform and varying bulk densities to examine which type of packing gave the greatest uniformity of penetration resistance (PR) with depth. The cylinders packed to a constant bulk density (1.48, 1.55, and 1.6 Mg m-3) all had measured PR profiles which increased markedly with depth by approximately 1, 1.5 and 3 MPa, respectively, within the top 100 mm. Between 100–300 mm depth, these same cylinders showed reductions in PR of up to 1, 2 and 2 MPa respectively. These results show that sand packed to a constant bulk density with depth would not provide a uniform mechanical impedance to plant roots.

Hydraulic Compaction Device for Making Soil Cores

AbstractIt is now well established that soil compaction of agricultural land used for crop production is a major problem. For basic laboratory investigations of soil compaction, it is important that multiple soil cores of varying bulk densities be reproduced within statistically acceptable ranges. A device was designed, constructed, and tested to consistently compact soil cores of varying dimensions and bulk densities. The device uses two opposing hydraulic cylinders to evenly compress soil samples. The compactor is designed to generate compacted cylinders varying from 50 to 100 mm in diameter and 25 to 150 mm in length. Bulk density values for 10 replications of a 150‐mm soil cylinder with a 50‐mm diameter did not vary significantly when compacted under a single pressure. Pressures of 0.35, 1.04, and 2.07 MPa produced cores having bulk densities of 1.66, 1.76, and 1.86 g cm−3, respectively. Approximately 10 cylinders per hour can be prepared with this device.