Increase In Initial Moisture Content Research Articles

Self-heating and spontaneous ignition of biomass storage piles: Towards a reliable prediction tool

Large-scale biomass storage for modern bioenergy introduces potential safety concerns due to the intrinsic self-heating of biomass. Despite this, very limited research has been conducted in this area. This project fills a critical gap by developing a comprehensive modelling framework for self-heating in biomass piles and conducting a series of experimental studies to explore the intricate sub-processes within these piles. This paper presents only a small portion of the modelling and testing work. It successfully demonstrates the model's usefulness in predicting self-heating in coal piles, guiding safety measures for coal storage. Among various storage parameters, the pile height, particle size and ambient wind velocity have been identified as having substantial impacts on self-heating and self-ignition within the coal pile. This paper also illustrates the pronounced effects of initial biomass moisture content on microbial reactivity and oxygen consumption rate. An increase in initial moisture content significantly enhances the overall microbial reactivity and oxygen consumption rate. Wheat straw, compared to rice straw, is more prone to self-heating under identical storage conditions, as evidenced by higher heat generation, faster oxygen consumption, and a shorter time to peak temperature. Moreover, microbial activity is found to play a critical role in biomass self-heating, particularly in the temperature range of 0–75 °C, during the initial stages of heat accumulation. For the modelling discussed here, the flow within the porous pile must be considered laminar, despite the highly turbulent flow around the pile. This is based on the Reynolds number, calculated from the in-pile volume average of the velocity and the mean diameter of the fuel particles, which is significantly below the critical threshold (Recr=200). The insights and sub-models to be derived from the relevant sub-processes in biomass pile can be integrated into the model framework. This integration will create a more comprehensive and robust model for predicting self-heating and self-ignition in biomass storage piles, enhancing both theoretical and practical management of these phenomena.

Dynamic resilient modulus of heavy-haul subgrade silt subjected to freeze-thaw cycles: Experimental investigation and evolution analysis

To investigate dynamic resilient modulus (MR) of heavy-haul subgrade silt, especially in seasonal frozen regions, a series of dynamic triaxial tests were performed after various freeze-thaw (FT) cycles. The specifically designed loading sequence was proposed for determining MR, which reflected the stress characteristics of subgrade induced by heavy-haul traffic load. Furthermore, the effects of numbers of FT cycles, initial moisture content, freezing temperature, deviator stress and confining stress were comprehensively considered as state variables. The results revealed that MR showed a decreasing trend with increase of numbers of FT cycles, where the attenuation stages for dynamic resilient modulus were divided into three stages, namely, rapid attenuation, slow attenuation and gradual cessation of attenuation. Then, the increase of initial moisture content and decrease of freezing temperature led to a decrease in MR, where the higher initial moisture content was, the more obvious deterioration effect was. Meanwhile, when the freezing temperature decreased to −15 °C, the appearance of the freeze shrinkage effect inhibited the damage to the soil skeleton, and the attenuation trend of MR was alleviated. The ensuing discoveries were that confining stress and deviator stress had hardening and softening effects on the thawed silt, respectively, leading to the increase and decrease in MR. In particular, when the initial water content was higher, the softening effect caused by deviator stress was more significant. To enhance the practicability, the predicted model for determining MR was proposed that included the coupled effects of the above variables. Furthermore, the fatigue life of typical asphalt pavement structures was calculated considering the damaged dynamic resilient modulus of silt subgrade duo to the freeze-thaw cycles. The outcomes illustrated that fatigue life of pavement structures with semi-rigid and flexible base reduced by 17.5% and 22.5%, respectively, via adopting the dynamic resilient modulus values under maximum attenuation state. This study could supply meaningful reference for safe and sustainable design of heavy-haul subgrade and asphalt pavement in seasonal frozen regions.

Laboratory Study on Entire Range Suction Measurement and Microstructure Change of Granite Residual Soil

The shear strength of unsaturated granite residual soil (GRS) will decline rapidly when moisture content increases, because of loss of matric suction in the soil. This can lead to slope instability and embankment collapse during rainfall. Determining the matric suction of GRS accurately at different conditions can improve the accuracy of stability analysis. Generally, matric suction can be characterized as the soil–water characteristic curve (SWCC), and it is closely related to soil microstructure. In this study, the entire range of matric suction was measured using a combination of pressure plate method, filter paper method, and vapor equilibrium method. Microstructure change was investigated based on mercury intrusion porosimeter tests, in which the pore size distribution (PSD) curves of GRS samples with different initial densities and moisture content were measured. The PSDs of samples before and after wetting were also measured and compared to investigate the influence of water intrusion. Test results indicate that the combination of measurement methods can cover the entire matric suction range. The microstructure of GRS with different initial conditions presents a clear bimodal PSD. At the same density, the increase in initial moisture content can increase intra-aggregate pores and decrease inter-aggregate pores. When initial density increases, only the volume of inter-aggregate pores decreases. Wetting can decrease inter-aggregate pores and increase intra-aggregate pores. Finally, the Li model is applied in SWCC fitting for tested samples, the result of which performs well with a high correlation coefficient (R2 > 0.95) and is recommended for GRS analysis.

Drying Kinetics of a Single Biomass Particle Using Fick’s Second Law of Diffusion

Drying has been widely studied as a necessary process in biomass utilization. The steam diffusion law plays an important role in drying kinetics. The drying kinetics of a single biomass particle using Fick’s second law of diffusion was studied in this paper. A parabolic relationship appeared between the critical moisture content and temperature. The critical moisture content decreased with the increase in drying temperature and the initial moisture content. The drying temperature had a significant effect on the effective diffusivity and coefficient of mass transfer during the dramatically falling period of the biomass drying process. However, it was affected by the effective diffusivity and coefficient of mass transfer during the slowly falling period. The initial moisture caused the opposite effect during the different periods. The normalized biomass moisture content generally increased with the increase in drying temperature, and decreased with the increase in initial moisture content. The initial moisture content had an effect on the normalized biomass moisture during the slowly rising period. Meanwhile, the drying temperature had an effect on the normalized biomass moisture during the whole period. The critical moisture content and the normalized biomass moisture content had negative relevant relationship. This study provides some valuable conclusions regarding the biomass drying process.

Mineralogical and Microstructural Characterization of Cement-Stabilized Soft Soils Based on Quantitative Analyses

The effects of cement dosage (percentage by dry soil weight) and initial moisture content (wo) on cement stabilized soft estuarine clay were investigated by effective integration of multi-quantitative analyses, including quantitative X-ray diffraction (XRD), thermalgravimetric analysis (TGA), Brunauer-Emmett-Teller (BET) test and scanning electron microscopy (SEM) with image processing. These quantitative analyses are highly complementary, which greatly improved the scientificalness of this research. The results revealed that the strength development of cement stabilized soft estuarine clay with varying cement dosages, and initial moisture content was ascribed to the combined influence of both soil fabric improvement and cementation bonding enhancement. The increase of wo resulted in larger clay particle spaces, which can counteract the enhancement of soil structure due to the rising hydration products. The hydration degrees of samples with fixed cement dosage but different wo are quite similar, while clay particle spaces were enlarged with an increase of initial moisture content. Thus, the same quantity of hydration products may bind more soil particles when pores are small at lower wo, thus increasing unconfined compressive strength (UCS). Furthermore, BET and quantitative SEM results illustrate that hydration degree plays a dominant role in the development of intra-aggregate pores (<0.2 μm), while wo affects inter-aggregate pores (0.2 μm–2 μm) more.

Physicochemical and hygroscopic properties of charcoals produced from residues of two tropical woods from Cameroon

ABSTRACT The aim of this study was to determine the physicochemical and hygroscopic properties of charcoals from Doussie (Afzelia africana) and Okan (Cylicodiscuis gabunensis), produced from residues of two tropical woods from Cameroon. The properties determined for these charcoals included physical (moisture content, basic density, high heating value) chemical (proximate analysis, ultimate analysis, FT-IR analysis), and hygroscopic (absorption and sorption) properties. Our results show that these properties differ between the two woods. Higher values were obtained with Okan, except for the fixed carbon content. A higher diffusion coefficient on water uptake was also observed with charcoal from Okan (3.25 × 10−8 ± 0.22 m2/s) compared to charcoal from Doussie (2.42 × 10−8 ± 0.21 m2/s). The highest equilibrium moisture contents in sorption are obtained with charcoal from Okan. Our results also reveal a relationship between hygroscopic behavior and charcoals properties. It was found theoretically that an increase of initial moisture content of charcoals about 19% caused a decrease in their initial fixed carbon content about 2% and in their initial high heating value about 2.5%. The charcoals studied are of good quality and meet the recommended standards for domestic use even in humid areas.

Drying Characteristics and Physicochemical Properties of Semi-Dried Restructured Sausage Depend on Initial Moisture Content.

Semi-dried restructured sausages are restructured meat products with a high nutritional and economic value. However, excessively long drying times can have negative effects on the energy consumption, texture, and sensory properties of semi-dried restructured sausages. The objective of this study was to investigate the effects of different water contents on the drying and physicochemical characteristics of semi-dried restructured sausages. Sausages were prepared with different initial moisture contents (0%−50%) and drying time (0−580 min). The drying characteristics, including the drying rate, effective moisture diffusivity, and water activity of sausage were significantly improved as the initial moisture content was increased. When the initial moisture content of the sausage was 50%, physicochemical properties, such as color, porosity, shear force, and volatile basic nitrogen, were improved the most along with the decreased drying time. Scanning electron microscopy data showed greater porosity and pore size in sausages with the increase of initial moisture content. Collectively, our data suggest that an increase in the initial moisture content of semi-dried restructured sausages improves their drying characteristics and physicochemical properties.

Effects of freeze-thaw cycles on the mechanical properties of cement-fiber composite treated silty clay

A composite improvement method was proposed by adding cement and fiber into the silty clay in order to enhance the stability and durability of the subgrade structure in the seasonally frozen area. The frost resistance of the composite treated silty clay is studied. Results show that the resilient modulus and unconfined compressive strength of cement-fiber composite treated soil decreases with increase of initial moisture content and the freeze-thaw cycles; the mechanical properties change obviously under the first freeze-thaw process, and tends to be stable after six freeze-thaw cycles. For the composite treated soil with 6% cement content, the optimum dosage of basalt fiber and polypropylene fiber is 1.0% and 0.15%–0.25%, respectively. Under the same moisture content and freeze-thaw cycles, the unconfined compressive strength of 0.15% polypropylene fiber composite soil is higher than that of 1.0% basalt fiber. Besides, a good linear relationship was found between unconfined compressive strength and resilient modulus of composite treated soil.

The mechanical properties and thermal conductivity of bamboo with freeze\u2013thaw treatment

The aim of this research was to investigate the effect of freeze–thaw treatment on bamboo with different initial moisture content (water-saturated, air-dried and oven-dried). Bamboo (Phyllostachys pubescens) were treated with two freeze treatments and its microstructure, chemical composition, mechanical properties and thermal conductivity were characterized by field emission scanning electron microscopy (FE-SEM), Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), mechanical testing machine and thermal conductivity tester, respectively. The results showed that the freeze–thaw treatment had little influence on the microstructure of bamboo, the chemical composition content and the cellulose crystalline structure of bamboo were also not altered. The crystallinity index was found to increase with the increase of initial moisture content. The bending strength and elastic modulus of the treated bamboo increased, the extent of the increase was dependent on the initial moisture content and the freezing temperature. The thermal conductivity of the treated bamboo increased remarkably, which might be possibly determined by the cellulose crystallinity, moisture content, and density of bamboo.

Effect of Organic Matter and Initial Moisture Content on Water Transmission Characteristics of Alfisols of Assam

A study was conducted to study the effect of organic matter and initial moisture content on water transmission behaviour of three texturally different Alfisols. Saturated hydraulic conductivity showed a variable increase with increase in organic matter. Soil water diffusivity D (θ) showed an irregular trend with increasing levels of organic matter while sorptivity (s) increased with increasing levels of organic matter, penetrability (P) of wetting front decreased. Weighted mean diffusivity did not show any particular trend amongst the treatments, however, it was found to be higher in treated soils as compared to untreated control. Specific water capacity increased with increasing levels of organic matter, while capillary conductivity (k) did not show any definite trend. All the water transmission parameters except sorptivity were found to be increased with an increase in initial moisture content. Diffusivity was in general higher at lower initial moisture content indicating that soil water diffusivity was greatly influenced by initial moisture content. Prediction of D (θ) was, by and large, satisfactory in coarse textured soils and inconclusive in case of K (θ) relation in most of the soils.

Effects of ball milling on the structure of cotton cellulose

Cellulose is often described as a mixture of crystalline and amorphous material. A large part of the general understanding of the chemical, biochemical and physical properties of cellulosic materials is thought to depend on the consequences of the ratio of these components. For example, amorphous materials are said to be more reactive and have less tensile strength but comprehensive understanding and definitive analysis remain elusive. Ball milling has been used for decades to increase the ratio of amorphous material. The present work used 13 techniques to follow the changes in cotton fibers (nearly pure cellulose) after ball milling for 15, 45 and 120 min. X-ray diffraction results were analyzed with the Rietveld method; DNP (dynamic nuclear polarization) natural abundance 2D NMR studies in the next paper in this issue assisted with the interpretation of the 1D analyses in the present work. A conventional NMR model’s paracrystalline and inaccessible crystallite surfaces were not needed in the model used for the DNP studies. Sum frequency generation (SFG) spectroscopy also showed profound changes as the cellulose was decrystallized. Optical microscopy and field emission-scanning electron microscopy results showed the changes in particle size; molecular weight and carbonyl group analyses by gel permeation chromatography confirmed chemical changes. Specific surface areas and pore sizes increased. Fourier transform infrared (FTIR) and Raman spectroscopy also indicated progressive changes; some proposed indicators of crystallinity for FTIR were not in good agreement with our results. Thermogravimetric analysis results indicated progressive increase in initial moisture content and some loss in stability. Although understanding of structural changes as cellulose is amorphized by ball milling is increased by this work, continued effort is needed to improve agreement between the synchrotron and laboratory X-ray methods used herein and to provide physical interpretation of the SFG results.

Isothermal drying kinetics of paddy using thermogravimetric analysis

The isothermal drying kinetics of paddy with three initial dry basis moisture content of 17.18, 21.05 and 30.12% have been studied by thermogravimetric analyzer. The results indicated that the final moisture content of the three samples with initial moisture content of 17.18, 21.05 and 30.12% decreased to 4.61, 5.63 and 7.61%, respectively, under the drying temperature of 50 °C. Moreover, the peak drying rate of the three samples speeds up from 1.41% min−1 to 2.18% min−1 with the increase in initial moisture content. Subsequently, five types of drying models were compared to determine the goodness of fit of the different experimental data generated under the drying temperature of 50 °C for the three samples. It is showed that correlation coefficients (R2) determined by Midilli et al. model for the three samples were larger than that in other four models, indicating that the model could fit the experimental data perfectly. Different drying temperature of 40, 50, 60 and 70 °C was selected for the calculation of the effective moisture diffusivity ranging from 3.9747 × 10−10 to 5.2519 × 10−10 m2s−1, which was eventually used to determine the activation energy. The results show that the activation energy of the three samples is 3.92, 5.23 and 6.82 kJ mol−1, respectively.

Wettability of commercial starches and galactomannans

ABSTRACTThis paper describes the wettability of basic commercial polysaccharides: starches (potato PS, wheat WS, corn CS, tapioca TS, kuzu KS) and galactomannans (fenugreek gum FG, guar gum GG, tara gum TG, locust bean gum LBG). The study was conducted using the Washburn capillary rise method and thermal drying. This allowed one to determine the material constant C, contact angle θ, surface free energy of solid SFE, and initial moisture content M. The measured values of contact angle θ and surface free energy SFE indicated that potato starch (70.9°, 41.1 mN · m−1) and wheat starch (88.4°, 30.2 mN · m−1) were characterized by the highest and lowest wettability among the examined starches, respectively. In turn, the galactomannans were poorly wettable substances. Their contact angles θ were approximately equal to 90°, showing a slight increase with increasing substitution degree. The observed decrease in surface free energy SFE from 30 to 29.6 mN · m−1 indicated a very minor hydrophobization of their surfaces. Material constant C was practically independent of temperature, and an increase in initial moisture content M in the examined starches and galactomannans proceeded according to the following schemes: CS < PS < WS < TS < KS and LBG < TG < GG < FG, respectively.

Simplified calculation method and its validation of infiltration capacity for film hole irrigation.

In order to simplify the numerical calculation of cumulative infiltration capacity under film hole irrigation, the film hole cumulative infiltration was decomposed into vertical infiltration capacity and lateral infiltration capacity, and lateral infiltration capacity of unit film hole perimeter was introduced to calculate film hole lateral infiltration capacity. The soil vertical one-dimensional infiltration characteristics and film hole infiltration characteristics were simulated by using HYDRUS-1D/3D software. According to the simulation results, the influence of film hole diameter on lateral infiltration capacity of unit film hole perimeter was analyzed. It was found that the film hole diameter had little impact on lateral infiltration capacity of unit film hole perimeter, and its impact on lateral infiltration capacity of unit film hole perimeter could be ignored. At present, the influence factors of one dimensional infiltration and film hole diameter on lateral infiltration capacity of unit film hole perimeter was the soil texture, initial moisture content and irrigation water depth. Based on this, the vertical one-dimensional infiltration depth and lateral infiltration capacity of unit film hole perimeter were quantitatively analyzed by using Philip infiltration model, and the influence of soil texture, initial moisture content and irrigation water depth on lateral infiltration coefficient and vertical one-dimensional infiltration coefficient were studied. The results showed that the soil texture had large impact on both the relative sorptivity rate(the ratio of sorptivity rate of lateral infiltration capacity of unit film hole perimeter to sorptivity rate of vertical one dimensional infiltration) and the relative steady infiltration rate(the ratio of steady infiltration rate of lateral infiltration capacity of unit film hole perimeter to steady infiltration rate of vertical one dimensional infiltration), the relative sorptivity rate decreased slightly with the increase of initial moisture content, the decrease amplitude of the relative sorptivity rate was 5.49%-24.72%, and irrigation water depth had less influence on relative steady infiltration rate, the maximum amplitude of the relative steady infiltration rate change was 21.80%. With respect to the relative steady infiltration rate, the change of relative sorptivity rate had less impact on cumulative infiltration capacity under film hole irrigation, to simplify the calculation, the relative sorptivity rate was considered as a fixed value for the same soil texture. The relative steady infiltration rate increased with the increase of irrigation water depth, the increase amplitude of the relative steady infiltration rate was 2.55%-42.76%, and the initial moisture content had little influence on relative steady infiltration rate, and the maximum amplitude of the relative steady infiltration rate change was 2.94%. To simplify the calculation of cumulative infiltration under film hole irrigation, only irrigation water depth was considered for its effect on the relative steady infiltration rate. The relationship between vertical infiltration coefficient and lateral infiltration coefficient was established. The simplified calculating model for cumulative infiltration capacity of film hole irrigation was proposed, including the film hole diameter, irrigation water depth, sorptivity of vertical one-dimensional infiltration and soil saturated hydraulic conductivity. The film hole infiltration parameters could be determined by using one-dimensional vertical infiltration parameters. The model was verified by infiltration experiments of one-dimensional vertical infiltration, experiments of film hole infiltration and the other researcher's experiment results. The results showed that the calculated values of experimental equation were consistent with the measured values(R2≥0.995, P<0.001), and the average relative error was about 5%(4.84%~6.81%). The equation proposed here only have 2 undetermined coefficients: vertical one-dimensional infiltration characteristics and film hole infiltration characteristics. It was simple enough for accurately predicting film hole infiltration characteristics. © 2016, Editorial Department of the Transactions of the Chinese Society of Agricultural Engineering. All right reserved.

Microwave drying kinetics and quality characteristics of corn

In recent years, microwave (MW) drying has gained popularity as an alternative drying method for a wide variety of food and agricultural products because of increasing concerns over product quality and production costs. However, the determination of drying kinetics that accurately describes microwave drying characteristics is crucial for the optimization of operating parameters, performance improvement of the drying system and product quality. The objective of this study was to investigate the drying kinetics and the quality characteristics of corn kernels, especially the effects of different initial moisture contents (18.3%, 26.3%, 34.3% and 42.3% db), MW power levels (70, 175 and 245 W) and exposure time (80 s and 120 s) on the drying kinetics, drying rate and various key quality parameters. The results indicated that the increased drying rate at higher power levels (P3, 245 W) reduced the drying time considerably but increased stress crack index and reduced germination. In addition, it reduced bulk density, true density and thousand grain weight (TGW). The germination rate of corn was the highest at MW power level P1 (70 W), with the lowest drying rate and observed to decrease with increase in initial moisture content. The reduction in exposure time decreased stress crack index and increased germination rate, bulk density and true density. The correlation analysis among drying rate, germination, stress-crack index (SCI), bulk density, true density and TGW showed that increasing drying rate could lead to an increase in SCI and decrease in germination, bulk density and true density.

基于季节性河床砂样的垂向非饱和入渗试验研究

基于季节性河床砂样，开展了垂向非饱和入渗室内试验，研究了影响垂向入渗的主要因素。结果表明，非饱和入渗随时间的变化可分为3个阶段，第1个阶段为入渗率迅速下降期，第2个阶段为入渗率缓慢下降期，第3个阶段为入渗率渐近稳定期；砂样的初始含水率、砂样质地对入渗特性产生明显影响。垂向入渗速度随着初始含水率的增大而减小，随着砂样干容重的增大而减小；当初始含水率分别为1.02%和5.11%时，细砂的稳定入渗率约为0.027 mL/(s•cm2)和0.021 mL/(s•cm2)；当初始含水率分别为1.38%和3.51%时，中砂的稳定入渗率约为0.028 mL/(s•cm2)和0.026 mL/(s•cm2)；当初始含水率分别为1.83%和5.92%时，粗砂的稳定入渗率约为0.030 mL/(s•cm2)和0.029 mL/(s•cm2)。粗砂的稳定入渗率大于细砂。试验结果对于深入研究季节性河道渗漏规律提供了科学依据。 Based on the seasonal river sand, laboratory test was carried out by vertical unsaturated infiltration and it studied the main factors influencing the vertical infiltration. The results show that the unsaturated in-filtration can be divided into three stages changing with time. In the first stage, the infiltration rate drops rapidly. In the second stage, the infiltration rate declines slowly. And in the third stage, the infiltration rate is asymptotically stable. The initial moisture content of sample and sample texture obviously influ-ence on infiltration characteristics. Vertical infiltration velocity decreases with the increase of initial moisture content, as the sample decreases with the increase of dry density. When the initial moisture content was 1.02% and 5.11%, the stability infiltration rate of fine sand was about 0.027 mL/(s•cm2) and 0.021 mL/(s•cm2). When the initial water content rate was 1.38% and 3.51%, the stability infiltration rate of medium sand was about 0.028 mL/(s•cm2) and 0.026 mL/(s•cm2). The initial moisture content was about 1.83% and 5.92% when the stability infiltration rate of coarse sand was about 0.030 mL/ (s•cm2) and 0.029mL/(s•cm2). The stability infiltration rate of the coarse sand is greater than the fine sand. The test results provide a scientific basis for the further study of seasonal river seepage law.

Study of the Impact of Initial Moisture Content in Oil Impregnated Insulation Paper on Thermal Aging Rate of Condenser Bushing

This paper studied the impact of moisture on the correlated characteristics of the condenser bushings oil-paper insulation system. The oil-impregnated paper samples underwent accelerated thermal aging at 130 °C after preparation at different initial moisture contents (1%, 3%, 5% and 7%). All the samples were extracted periodically for the measurement of the moisture content, the degree of polymerization (DP) and frequency domain dielectric spectroscopy (FDS). Next, the measurement results of samples were compared to the related research results of transformer oil-paper insulation, offering a theoretical basis of the parameter analysis. The obtained results show that the moisture fluctuation amplitude can reflect the different initial moisture contents of insulating paper and the mass ratio of oil and paper has little impact on the moisture content fluctuation pattern in oil-paper but has a great impact on moisture fluctuation amplitude; reduction of DP presents an accelerating trend with the increase of initial moisture content, and the aging rate of test samples is higher under low moisture content but lower under high moisture content compared to the insulation paper in transformers. Two obvious “deceleration zones” appeared in the dielectric spectrum with the decrease of frequency, and not only does the integral value of dielectric dissipation factor (tan δ) reflect the aging degree, but it reflects the moisture content in solid insulation. These types of research in this paper can be applied to evaluate the condition of humidified insulation and the aging state of solid insulation for condenser bushings.

Effects of species and moisture content on penetration of liquid in laser incised lumber by the passive impregnation method

Penetration of liquid by passive impregnation method for Douglas-fir (Pseudotsuga menziesii Franco), sugi (Cryptomeria japonica D. Don) and Japanese larch (Larix leptolepis Gordon) was studied. Effects of initial moisture content of sugi (16, 43 and 70% moisture content) on liquid penetration were also studied. Dried Douglas-fir (mc=14%) and sugi (mc=16%), and green Japanese larch (mc=45%) and sugi (mc=70%) were treated by passive impregnation method for penetration analysis. It was observed that dried sugi had the highest level of liquid penetration both in length (170 mm) and width (8 mm) for all measured sections followed by green sugi, green Japanese larch and dried Douglas-fir. In case of different initial moisture content, the highest absorption (624 kg/m3) and penetration (maximum 87 and 96% at cross and longitudinal surfaces, respectively) was observed for sugi having the lowest initial moisture content under the same passive impregnation conditions. Absorption and penetration decreased with the increase of initial moisture content for sugi. These results could help in designing incising pattern and density, as well as solving the problems related to high initial moisture content of wood for passive impregnation.

Microwave vacuum drying characteristics of Pinus massoniana wood

Microwave-vacuum (MV) drying characteristics of plantation Masson pine (Pinus massoniana) were studied experimentally for various levels of microwave radiation time, initial moisture content (MC), vacuum level and wood thickness. The results show that the process of MV drying for wood can be significantly divided into a short accelerating rate drying period, a long constant rate drying period and falling rate drying period, and the second drying period can extend to levels of mean MC below the fiber saturation point. With the increase of initial MC and microwave radiation time, the drying rate of wood increases significantly. The vacuum level affects the drying rate in a slightly positive way. Within the range of 2 to 6 cm, the effects of sample thickness on the drying rate can be negligible.

Drying and Urease Inactivation Models of Soybean Using Two-dimensional Spouted Bed Technique

The most important factors for examining the quality of soybeans in the animal feed industry are moisture and urease inactivation. Mathematical models for soybean drying and urease inactivation using two-dimensional spouted bed are developed and validated with experimental data. The influences of initial moisture content, inlet air temperature, air recycle on the drying rate, urease inactivation, and energy consumption are also studied. The results revealed that the increase in initial moisture content slightly affected the drying rate and urease inactivation while the inlet air temperature caused a significant effect. To obtain a high drying rate and save energy consumption, the recycle air ratio should be kept in a range of 80–90%.