Drying Temperature Effect on Kernel Damage and Viability of Maize Dried in a Solar Biomass Hybrid Dryer

Though several maize varieties have been developed and introduced over the years in Ghana, farmers still face challenges of access to quality seed maize. Among the major constraint is lack of proper drying systems to guarantee quality of seed produced. As in most parts of Africa, drying of maize in the open, on bare ground along shoulders of roads is still a common practice in Ghana. In this study, a 5-tonne capacity hybrid solar biomass dryer was developed for drying maize for seed and food/feed in Ghana. Effect of air temperature in the dryer on the physiological quality and germination of maize kernels was investigated. Maize grains were dried in the open sun simulating farmers practice and using the dryer at 4 varying levels (L1, L2, L3 and L4) with corresponding heights (0.6 m, 1.2 m, 1.8 m and 2.4 m, respectively) from the ground. Harvested maize at 22.8% moisture content was dried at the varying levels until reaching the final desired moisture content of 12.8% ± 0.2% (wb). Results showed that, air temperatures in the dryer increased in accordance with height with lowest mean temperature of 44.4&degC ± 4.6&degC recorded at L1 and mean maximum of 52.8&degC ± 5.4&degC at L4. Drying temperatures recorded at L1 - L3 and ambient had no significant effect (p < 0.05) on kernel damage and viability. Drying conditions at L1-L3 were considered optimum (<50&degC) for kernel drying compared to the topmost tray, L4. Kernel stress crack index (multiple and checked) was therefore reduced on average by 14% while kernel germination increased by 33%. This satisfies the dryer’s potential to be used for commercial drying of maize grains for seed production for smallholder farmers in Ghana.

Experimental Study and Modeling of a Convective Dryer for Fruits and Vegetables

The present work deals with the study of the thermal performances of a convective dryer for fruits and vegetables. This dryer, operating with energy generated from the combustion of biomass in a boiler connected to a water/air heat exchanger could be a solution to the problematic of energy related to drying. An experimental and theoretical study is carried out on the temperature profile inside the dryer. For this purpose, 10.3 kg of tomatoes were dried on the experimental setup. The operation lasted about 16 hours and reduced the moisture content from 93.8% to 12% in wet basis. The overall thermal efficiency of the convective dryer during the trial is 10.76%. For the theoretical study, the dryer components (boiler, water/air exchanger and drying chamber) are first modeled individually;the different sub-programs are then coupled to form the convective dryer program. The method of global heat balances combined with the one called “ε-NUT” is used. The set of equations is discretized using the implicit method of finite differences, then solved with the Gauss algorithm in Fortran 90. The theoretical results obtained are in good agreement with those measured.

Stem and Total Above-Ground Biomass Models for the Tree Species of Freshwater Wetlands Forest, Coastal Areas and Dry Areas of Bangladesh: Using a Non-Destructive Approach

Biomass and carbon stock in a forested areas are now prime important indicators of forest management and climate change mitigation measures. But the accurate estimation of biomass and carbon in trees of forests is now a challenging issue. In most cases, pantropical and regional biomass models are used frequently to estimate biomass and carbon stock in trees, but these estimations have some uncertainty compared to the species-specific allometric biomass model. Acacia nilotica, Casuarina equisetifolia and Melia azedarach have been planted in different areas of Bangladesh considering the species-specific site requirements. While Barringtonia acutangula and Pongamia pinnata are the dominant tree species of the freshwater swamp forest of Bangladesh. This study was aimed to develop species-specific allometric biomass models for estimating stem and above ground biomass (TAGB) of these species using the non-destructive method and to compare the efficiency of the derived biomass models with the frequently used regional and pantropical biomass models. Four Ln-based models with diameter at breast height (DBH) and total height (H) were tested to derive the best fit allometric model. Among the tested models, Ln (biomass) = a + b Ln (D) + c Ln (H) was the best-fit model for A. nilotica, M. azedarach, B. acutangula and P. pinnata and Ln (biomass) = a + b Ln (D2H) was best-fit for C. equisetifolia. Finally, the derived best-fit species-specific TAGB models have shown superiority over the other frequently used pantropical and regional biomass models in relation to model efficiency and model prediction error.

废弃秸秆等生物质低能耗非相变秒级干燥

自主研发并设计搭建了生物质非相变旋流干燥的小试和中试实验装置。小试实验结果表明,在最佳干燥条件下秸秆含水率可从68%降至15%左右,脱水效率可达70%以上,放大规模的实验在中试装置上进行了验证。仿真模拟研究揭示了旋流场内切向、径向和轴向速度对固液分离的影响。理论计算结果表明干燥过程脱除的水分中有64.81%以非相变液滴形式脱离,说明非相变在干燥过程中占主要地位。机理研究表明水分可从生物质孔道中分离,这是由于生物质在旋流场中发生自公转耦合运动,导致其表面形成孔道,使水分以微液滴形式脱除。此外还对玉米胚芽、酒糟、木屑等生物质进行了实验,均达到接近70%的脱水效率,证明了该技术对生物质种类的普适性。

城市污泥干燥动力学特性及其与生物质共气化热电联产系统模拟

对城市污泥进行高效干燥预处理及气化资源化利用是实现城市绿色可持续发展的重要途径之一。首先,利用热重反应器研究了污泥的干燥动力学特性;其次,基于Fluent数值模拟软件明晰了高温低速烟气和低温高速烟气对污泥干燥过程的影响;最后通过Aspen Plus构建了新型的污泥与生物质共气化热电联产系统,并讨论了系统的热力性能。结果表明:污泥在热重反应器中的干燥过程分为升速阶段、第一降速阶段和第二降速阶段,以降速阶段为主;SW-60、SW-80的水分扩散系数范围分别为6.34×10^(-6)~3.72×10^(-5)m^(2)/s和3.69×10^(-5)~2.60×10^(-4)m^(2)/s;初始含水率的提高会增加污泥干燥活化能,SW-60、SW-80的干燥活化能分别为9.55 kJ/mol和28.25 kJ/mol;干燥床中高温低速烟气的干燥效率大约为低温高速烟气的2.67倍;在热电联产系统中,随着生物质掺混比例的增加,输入热量、空气流量、合成气低位热值、合成气产率和热电联产潜力均随之增加,然而电效率、热效率和系统效率会缓慢下降;当生物质掺混质量比为20%时,每千克30%含水率干污泥与生物质的共混物可以产生电能与热能潜力分别为0.61 k W·h和4.212 MJ。

基于生物混凝剂的太湖蓝藻生物质气浮收获与微波干燥中试系统研究

文章提出一种基于生物混凝剂的蓝藻生物质混凝-气浮收获与微波干燥工艺,开发了处理量为20 m^(3)/h的中试系统。在太湖的连续运行结果表明:该系统对蓝藻生物质的收获效率高达95%,脱水后生物质的含水率可降低到85%以下;经微波连续干燥10 min后,生物质含水率可以降低到10%以内,且微波干燥对生物质中的蛋白质和糖类等主要营养物质的含量没有影响。经济性分析和成本敏感性分析结果表明,蓝藻生物质的收获与干燥总成本为4134.1元/t,其中生物混凝剂成本占50%以上,蓝藻生物质处理成本与生物混凝剂用量和成本以及微波干燥量密切相关。

辽宁地区清洁能源技术在粮食干燥中的应用研究

为了研究生物质成型燃料、新型环保乳化燃油和电热储能3种清洁能源在辽宁省粮食干燥应用情况。通过测试不同清洁能源在粮食干燥系统中应用的各项参数,计算了实际生产中的系统性能,分析了不同清洁能源在粮食干燥应用的经济效益。结果表明,3种清洁能源均能够满足粮食干燥的需求,且技术可靠、干燥成本低。生物质热风炉平均热效率为73.8%,乳化燃油热风炉平均热效率为84.3%,电热储能热风炉热效率为85.4%。

生物质颗粒生产线烘干设备设计

生物质能源是一种可再生能源,也是一种清洁能源,开发和利用生物质能源产品能够实现资源的循环利用,减少环境污染和资源浪费,有助于实现可持续发展。在生物质颗粒生产线中,烘干设备用于去除生物质颗粒原料中的水分。如果原料水分含量过高,会导致生物质颗粒在运输和储存时发生潮解和变质。烘干机的选型、结构设计和操作参数会影响烘干效率,进而影响生物质颗粒的质量。对不同类型的烘干机进行分析,选择滚筒式烘干机作为生物质颗粒生产线的理想烘干设备,然后重点对滚筒式烘干机进行结构设计。

Above-ground Biomass Allocation in a Planted Forest in a Semi-arid Region of Northern Mongolia

Investigation of the above-ground biomass allocation patterns on Scots pine plantations is critical for quantifying the productivity and carbon cycle of forest ecosystems. We estimated above-ground biomass and net primary production of a 25-year-old Pinus sylvestris L. （Scots pine） plantation, in a semi-arid region of Mongolia. The above-ground biomass of sample trees was divided into stem wood, stem bark, live branches, dead branches and needles. Total biomass for the stand was only 18.03 Mg ha1, of which 47.6% was found in stem wood, 25.8% in live branches and 14.8% in needles. The growth rate of the Scots pine plantation in the study region was relatively low compared with other regions. In the study area, it was observed that the rate of biomass accumulation in the plantation was very slow; this can be explained by very limited growing conditions and intensive crown closure. The results from this study indicate that it may be necessary to carry out thinning to increase biomass production by reducing competition between trees in the Scotch pine plantation.

大豆玉米复合种植模式中2种作物的互作关系

定量化探索中国北方在平水年下,不同大豆玉米复合种植模式的种间竞争与种间互惠关系,以期为旱作条件下选择合理的牧草种植模式提供理论依据。试验选用我国中南部春播区推荐的作物品种大豆铁丰31和玉米强盛199,在旱作区域开展不同大豆玉米带状复合种植模式的大田栽培试验,采用完全随机区组设计4种大豆玉米带状复合种植模式,同时以大豆与玉米清种作为对照,测定不同种植模式下的生物量、邻体效应指数(RII),比较不同种植模式下大豆和玉米的互作关系。结果显示,大豆RII为-0.28~0.13,玉米RII为-0.28~0.12。在6行大豆3行玉米(S6M3)复合种植模式下,大豆和玉米的生物量较清种对照分别增加了28.95%和27.79%,且高于其他复合种植模式下作物生物量;大豆和玉米的RII分别为0.13和0.12,二者存在正相互作用。综上,在与试验区年降雨量相差不明显的旱作区域,选择S6M3复合种植模式有望提高青贮饲料产量。

Estimation of biomass in wheat using random forest regression algorithm and remote sensing data

Wheat biomass can be estimated using appropriate spectral vegetation indices.However,the accuracy of estimation should be further improved for on-farm crop management.Previous studies focused on developing vegetation indices,however limited research exists on modeling algorithms.The emerging Random Forest(RF) machine-learning algorithm is regarded as one of the most precise prediction methods for regression modeling.The objectives of this study were to(1) investigate the applicability of the RF regression algorithm for remotely estimating wheat biomass,(2) test the performance of the RF regression model,and(3) compare the performance of the RF algorithm with support vector regression(SVR) and artificial neural network(ANN) machine-learning algorithms for wheat biomass estimation.Single HJ-CCD images of wheat from test sites in Jiangsu province were obtained during the jointing,booting,and anthesis stages of growth.Fifteen vegetation indices were calculated based on these images.In-situ wheat above-ground dry biomass was measured during the HJ-CCD data acquisition.The results showed that the RF model produced more accurate estimates of wheat biomass than the SVR and ANN models at each stage,and its robustness is as good as SVR but better than ANN.The RF algorithm provides a useful exploratory and predictive tool for estimating wheat biomass on a large scale in Southern China.

Stand-level biomass models for predicting C stock for the main Spanish pine species

Background:National and international institutions periodically demand information on forest indicators that are used for global reporting.Among other aspects,the carbon accumulated in the biomass of forest species must be reported.For this purpose,one of the main sources of data is the National Forest Inventory(NFI),which together with statistical empirical approaches and updating procedures can even allow annual estimates of the requested indicators.Methods:Stand level biomass models,relating the dry weight of the biomass with the stand volume were developed for the five main pine species in the Iberian Peninsula(Pinus sylvestris,Pinus pinea,Pinus halepensis,Pinus nigra and Pinus pinaster).The dependence of the model on aridity and/or mean tree size was explored,as well as the importance of including the stand form factor to correct model bias.Furthermore,the capability of the models to estimate forest carbon stocks,updated for a given year,was also analysed.Results:The strong relationship between stand dry weight biomass and stand volume was modulated by the mean tree size,although the effect varied among the five pine species.Site humidity,measured using the Martonne aridity index,increased the biomass for a given volume in the cases of Pinus sylvestris,Pinus halepensis and Pinus nigra.Models that consider both mean tree size and stand form factor were more accurate and less biased than those that do not.The models developed allow carbon stocks in the main Iberian Peninsula pine forests to be estimated at stand level with biases of less than 0.2 Mg·ha^(-1).Conclusions:The results of this study reveal the importance of considering variables related with environmental conditions and stand structure when developing stand dry weight biomass models.The described methodology together with the models developed provide a precise tool that can be used for quantifying biomass and carbon stored in the Spanish pine forests in specific years when no field data are available.

Responses of Dry Bean to 2,4-D Ester Applied Preplant and Preemergence

Six field studies were completed in Ontario (during 2016 to 2018) to assess the tolerance of adzuki, kidney, small red and navy bean to 2,4-D ester at 528 or 1056 g&middot;ai&middot;ha-1 applied 14, 7 and 1 day before seeding (PP) and 3 days after seeding (PRE). 2,4-D applied PP or PRE caused as much as 4%, 6%, 7% and 8% injury in adzuki, kidney, small red and navy (white) bean, respectively. There was an increase in bean injury as the preplant interval decreased. At 1 WAE, 2,4-D applied at 1056 g&middot;ai&middot;ha-1 14, 7 and 1 day PP and 3 days after seeding caused up to 6%, 10%, 18% and 5% visible bean injury, respectively. The level of injury decreased over time with minimal bean injury (0 to 3%) at 8 WAE. Bean stand counts were similar to the non-treated control with 2,4-D applied at various timings except at 1 day PP when 2,4-D at the 2X rate decreased bean stand 13%. There was up to 23% and 43% decrease in bean dry weight with 2,4-D applied PP at 528 and 1056 g&middot;ai&middot;ha-1 7 and 1 day PP, respectively. Bean height (6 WAE) was not affected by 2,4-D applied at various timings except at 1 day PP when 2,4-D (1056 g&middot;ai&middot;ha-1) decreased bean height 10%. Additionally, there was no effect of 2,4-D treatments on bean maturity or yield. Based on these results, the safest times to apply 2,4-D are 14 days before seeding or PRE. Injury was higher when 2,4-D was applied 7 and 1 day PP. Injury was lower in adzuki bean compared to kidney, small red or navy bean.

Fluidized Bed Superheated Steam Dryer for Bagasse: Effects of Particle Size Distribution

Fluidized bed superheated steam drying is one of the technologies successfully applied to drying pulp in the sugar beet industry. It has the technological advantages of energy efficiency and safety (inert environment) required for use in drying bagasse. A comparison of the particle size distribution of bagasse and beet pulp was evaluated in terms of fluidization. The size distribution of bagasse particles is from 2 to 10 times broader than the equivalent distribution of beet pulp particles. The mean particle size of the bagasse is 1/3 of the mean size of the beet pulp. Fluidization tests proved that bagasse fluidization is possible. It was found that beet pulp and bagasse particles clearly differ on shape and size distribution which in turn will affect the design of the ancillary equipment and the fluidization systems if sugarcane bagasse is to be dried using superheated steam technology.

Effect of Lime and Phosphorus on Yield and Yield Components of Groundnut Varieties [Arachis hypogaea L.] on Acidic Soil in Nedjo District, Western Ethiopia

Groundnut (Arachis hypogaea L.) is an important cash crop for smallholder farmers in western Ethiopia. However, the yield of the crop is very low mainly because of strong soil acidity and poor soil fertility management. A study conducted to evaluate the effect of lime and mineral phosphorus fertilizer on yield components and yield of groundnut. The treatments consisted of three phosphorus rates (0, 46 and 92 kg P2O5·ha-1), three lime rates (0, 6, and 11 ton lime·ha-1), and three groundnut varieties (local cultivar, Werer-961, and Werer-963) was laid-out as a randomized complete design in a factorial arrangement with three replications. The corresponding rates of phosphorus applied per pot of soil (7 kg) amounted to 0, 107 and 215 mg kg·soil-1 and those of lime amounted to 0, 14, and 26 g kg·soil-1. The analysis of variance showed that phenological characters, yield, and yield components significantly affected by interaction of variety, phosphorus, and lime. The highest dry pod yield produced by Werer-963 (2 kg dry pod yield·pot-1) in response to the application 11 t·ha-1 lime and 46 kg P2O5·ha-1. However, Werer-961 produced medium (1.5 kg dry pod yield·pot-1) at 11 t·ha-1 lime and 92 kg P2O5·ha-1 and the local cultivar produced minimum (1 kg dry pod yield·pot-1) at the application of 11 t·ha-1 lime and 92 kg P2O5·ha-1. In terms of phosphorus yield efficiency index, Werer-963 was highly efficient (index of 1.71), and Werer-961 was moderately efficient (index of 0.6). However, the local cultivar was inefficient (index of 0.04). It is at, in acidic soil of the study area Werer-963 is the best to be cultivated with application of lime 11 t·ha-1 and 46 kg P2O5·ha-1 fertilizer, followed by Werer-961. The results of this pot experiment have revealed that farmers in the study area need to switch to cultivating the improved varieties of groundnut rather than local variety with the application of high rates of lime and moderate amounts of phosphorus.

短期氮添加对高寒草地植物高度和生产力的影响

研究不同氮添加梯度和频次下草地生产力、植物高度、水分含量和干鲜比的变化趋势,利用样方调查法调查巴音布鲁克草原代表性物种,分析高寒草地常见植物高度、生产力和干鲜比比值.结果表明:该地区整体植物群落高度变化不显著,蔷薇科(Rosaceae)植物高度受氮添加梯度和频次的影响较大,禾本科(Poaceae)植物高度在两种氮添加频次下影响显著.莓叶委陵菜(Potentilla fragarioides)、冰草(Agropyron cristatum)、羊茅(Festuca ovina)植物高度在两种氮添加频次下差异显著.不同氮添加梯度和频次对植物地上生产力影响显著,随氮添加梯度的提升植物地上生产力呈现出增加趋势,禾本科植物生产力受氮添加因素的影响显著,蔷薇科和豆科(Fabaceae)植物生产力变化不大.巴音布鲁克草地植物的含水量介于35.10%~45.87%,干鲜比介于54.13%~64.90%.

臭氧污染对亚热带森林生产力和生物量的影响——以鼎湖山为例

全球气候变化背景下,我国近地面臭氧浓度不断增加,已严重威胁到森林生态系统。但是,目前臭氧污染影响我国亚热带森林生物量的研究仍然具有较高的不确定性。本研究比较了不同模型和不同参数化方案评估的鼎湖山森林和林下草地生物量损失率的差别,比较了鼎湖山阔叶林和针叶林以及林下草地的生物量损失率与总初级生产力(GPP)损失率的一致性。2015—2016年臭氧污染造成的鼎湖山阔叶林生物量损失率为11.3%—11.69%,针叶林生物量损失率为3.97%—3.68%,草地生物量损失11.2%—14.6%;不同参数化方案估计的鼎湖山阔叶林的生物量损失率在9%—13%之间,针叶林的生物量损失率在3.68%—4.4%之间变化,草地在11.2%—14.6%之间。基于臭氧剂量响应关系模型估算的阔叶林GPP损失率为10%—12.6%,针叶林GPP损失率为1.81%—2.6%,草地GPP损失率为3.2%—3.3%。总的来看,鼎湖山阔叶林和针叶林的生物量和GPP损失具有较高的一致性,阔叶林生物量和GPP的损失率明显高于针叶林生物量和GPP的损失率。

生物质储藏技术研究进展

在全面响应“碳达峰”“碳中和”的背景下,需对典型可再生资源——生物质的利用与储藏进行研究。现有关于生物质直接储藏的研究大多借鉴的是堆肥、食品贮藏、秸秆青贮等技术的研究方法,对生物质在储藏阶段的温室气体排放不够重视。生物质储藏能够弥补原料采收、供应和需求之间的差异,是生物质供应链的核心环节。回顾了生物质储藏的概念、自发热与干物质损失机理,对比了生物质储藏技术与堆肥、厌氧消化、成型燃料储藏等传统技术。在此基础之上阐述了生物质储藏过程中产生温室气体的机理,并提出了减少干物质损失的新方法。在已有研究成果的基础上加大对储藏技术的研发投入,提高生物质储藏效率,可为生物质原料的绿色高效储藏提供依据。

不同土壤和微量元素对车桑子幼苗生长的影响

为了解微量元素对车桑子(Dodonaea viscosa)生长的作用,研究添加微量元素(硼B、铁Fe、锰Mn、锌Zn)对车桑子生长和叶绿素荧光特性的影响。结果表明,除Mn外,B、Zn和Fe均对车桑子的生长和叶绿素荧光参数有显著促进作用(P<0.05);且添加B的车桑子具有更高的生物量积累,比对照显著提高了133.61%。微量元素与土壤类型对叶片磷(P)含量和叶片氮磷比(N/P)具有显著的交互作用(P<0.05),紫色土添加Zn、黄棕壤添加Fe均显著降低了叶片N/P。燥红土和黄棕壤上车桑子的株高、叶面积和生物量积累均高于紫色土,但紫色土和黄棕壤上车桑子的根冠比和叶片N/P显著高于燥红土(P<0.001)。这表明微量元素对干热河谷车桑子生长具有重要作用,在植被恢复过程中可通过添加B、Fe、Zn尤其是B来促进植物生长。

Development and Evaluation of an All Weather-Type Solar Drying House to Make for Wood Pellet Material

To suppress the global environment pollutions, we tried to develop a new-type solar drying house by improving a typical agricultural green-house, so that an all weather-type solar drying house was invented ultimately. This house is capable to dry raw wood materials (Ogako) into suitable moisture content (Mc) to make a wood pellet. The all weather-type solar Ogako drying house is covered with a triple transparent film, and an open/close free-type shield sheet is spread along with house’s inner surface with a small space, which is opened when solar radiation is incident on the house in daytime and closed to prevent heat loss from the house while out of sun shining in night. Inside of the all weather-type solar Ogako drying house, there are four belt-conveyors over which four top radiation panels are hanged, and on which four Ogako agitators are touched, a turn-table, two hoppers, four small fans, and besides, a floor heating is molded in concrete floor. Also on the north wall outside the house, two insulated cylinders (chimney) are stood up vertically to exhaust inside moist air passively. Then, to make clearly the operation performance of the house, the drying tests for the proof examination were conducted nineteen times at first test site in Ashoro where is located east-central part of Hokkaido, Japan. As a result of the drying test for the proof examination, it was made clear that the all weather-type solar Ogako drying house is practically useful as a supplementary apparatus to produce the dried Ogako, and consequently to suppress CO2 exhaustion.