燃用掺混小比例生物柴油对船舶柴油机性能的影响

为探究生物柴油在船舶柴油机上的适用性,基于六缸中速柴油机试验台架,在不同负荷推进特性工况下,对燃用0#柴油、B10生物柴油柴油机的动力性能、经济性能、振动特性和缸内燃烧特性进行对比分析。结果发现：与0#柴油相比,燃用B10生物柴油柴油机的输出功率和耗油量基本不变,耗油率有所升高,但随着负荷的升高有所改善,燃用B10生物柴油使得在25%负荷工况下的柴油机缸盖振动烈度下降,50%、75%、90%、100%负荷工况下的柴油机缸盖振动烈度稍有上升,不同负荷工况下的机体振动烈度均下降;从振动功率谱密度可以看出,两种燃油在不同负荷下低频段的振动响应相似,但高频段处振动响应存在差异;对两种燃油的缸内压力和压力升高率曲线的分析可知,燃用B10生物柴油可以使缸内压力峰值和最大压力升高率升高,燃烧反应速度加快。综上,B10生物柴油在不同负荷工况下动力性能、经济性能、振动特性和缸内燃烧特性方面均表现良好,在船舶柴油机上具有较好的应用前景。     

生物柴油掺氨对均质压燃发动机燃烧及排放性能的影响

为提升燃料的综合燃烧品质和性能,进一步降低有害物质排放和缓解温室效应,以燃烧动力学和化学反应机制作为理论基础,采用Chemkin软件将生物柴油替代物和氨气充分融合,模拟并计算氨气掺混比例分别为0、5%、10%、15%、20%的5组燃料在均质压燃发动机模式下燃烧和排放指标的数值,对比分析得到不同掺混比例对发动机燃烧和排放的影响和变化规律。结果表明：随着氨气掺混比例增加,燃料的点火滞燃期有所缩短,缸内燃烧最高温度升高,排温降低;排放方面,NO_x的排放升高,CO₂、CO和总碳氢化合物(THC)的排放均明显降低;生物柴油掺混氨气的最佳比例为20%,此时发动机功率下降12百分点,NO的单位功率排放升高了0.003 kW^-1,而CO₂和THC的单位功率排放分别降低了0.01 kW^-1和0.001 3 kW^-1。综上,生物柴油掺混氨气后改善了燃烧性能,降低了排放量,具有良好的应用前景。     

餐厨废弃油脂生物柴油对船舶柴油机性能、排放特性以及燃烧特性的影响北大核心CSCD

为探讨生物柴油应用于船舶柴油机的可行性,将餐厨废弃油脂生物柴油与柴油混合,在船舶柴油机上进行试验,测试其对船舶柴油机性能、排放特性和燃烧特性的影响。结果表明:生物柴油混合物的高黏度以及低热值会降低有效热效率,并导致燃油消耗率略有升高;由于生物柴油的高含氧量促进完全燃烧,相比于柴油,燃烧生物柴油混合物后,一氧化碳排放量最高下降17%,二氧化碳排放量最高下降5.1%,二氧化硫排放量最高下降41%,碳烟排放量最高下降36%;生物柴油过快的燃烧速率提高了气缸内的燃烧温度,以及高含氧量促进了氮氧化物的排放;生物柴油混合物燃烧时的缸内压力与柴油非常接近。餐厨废弃油脂生物柴油对船舶柴油机的性能、燃烧特性和排放特性均具有较好的表现,可以作为柴油的替代燃料用于船舶柴油机。     

生物柴油的燃烧及排放特性研究

在一台四冲程直喷式柴油机上对比研究不同喷油策略对鱼油乙酯生物柴油混合燃料燃烧和排放特性的影响。发动机转速固定在1 500 r/min,喷油正时分别在21、24、27°CA BTDC的不同负荷下,使用的6种燃料为柴油及B20、B40、B60、B80、B100的鱼油乙酯生物柴油混合燃料。结果表明:在不同喷油正时、不同负荷下,生物柴油与柴油相比,发动机的氮氧化物和碳烟排放最大降幅为17.9%和55.38%;鱼油制取的生物柴油导致气缸压力峰值、放热率和最大压力升高率均低于柴油,碳氢化合物、一氧化碳排放降低。     

混合燃料中生物柴油掺混比例对发动机性能影响的研究

为了研究高原环境下生物柴油-乙醇-柴油混合燃料中生物柴油对柴油发动机性能的影响,选用纯柴油、B15E3(生物柴油体积分数为15%,乙醇体积分数为3%和柴油体积分数为82%)和B25E3(生物柴油体积分数为25%,乙醇体积分数为3%和柴油体积分数为72%)在柴油发动机YN30CR上进行试燃,在最大扭矩转速工况下比较3种燃料的燃烧性、经济性和排放性差异。结果表明:燃烧混合燃料的发动机动力性下降,B25E3下降明显,缸内压力峰值下降1 MPa,压力升高率峰值下降0.14 MPa/°CA;燃烧B15E3和B25E3的瞬时放热率峰值较纯柴油低4.8%、5.6%;当量燃油消耗量低于纯柴油,燃油经济性有一定改善;中低负荷下,纯柴油当量燃油消耗量最高,B25E3的当量燃油消耗量低于B15E3,高负荷下,燃烧B25E3的当量燃油消耗量稍高于B15E3;燃用B15E3和B25E3后,碳烟排放低于燃烧纯柴油,B25E3改善幅度大于B15E3,随着负荷的增加,碳烟排放性的改善较为明显。     

EGR对天然气HCCI发动机排放的影响

本文基于CHEMKIN程序,对天然气燃烧的详细化学反应机理通过敏感性分析及反应速率分析的方法,构建了甲炕燃烧的简化化学反应机理。将该简化模型与计算流体动力学软件（FLUENT）耦合进行模拟计算,分析不同EGR率对天然气HCCI发动机燃烧和排放的影响,计算结果表明：随着EGR率的增加,燃烧着火始点有所推迟,最高燃烧压力下降,缸内最高温度降低,NO排放量明显减少,CO和甲醛（CH20）排放量有所增加。     

EGR对天然气HCCI发动机排放的影响

本文基于CHEMKIN程序,对天然气燃烧的详细化学反应机理通过敏感性分析及反应速率分析的方法,构建了甲烷燃烧的简化化学反应机理。将该简化模型与计算流体动力学软件(FLUENT)耦合进行模拟计算,分析不同EGR率对天然气HCCI发动机燃烧和排放的影响,计算结果表明:随着EGR率的增加,燃烧着火始点有所推迟,最高燃烧压力下降,缸内最高温度降低,NO排放量明显减少,CO和甲醛(CH2O)排放量有所增加。     

橡胶籽生物柴油在柴油发动机上的应用研究

以0#轻柴油、-10#军用柴油为对比燃油,对调和生物柴油B5、B20(橡胶籽生物柴油含量分别为5%、20%,常规柴油含量分别为95%、80%)在WD61550柴油发动机上进行适应性研究,考察了柴油机燃用不同燃油时的外特性、负荷特性,测定了功率、扭矩、油耗等性能指标。研究结果表明,发动机使用调和生物柴油的外特性、负荷特性参数变化趋势与所用对比燃油一致;使用调和生物柴油B5时,发动机动力性、经济性与0#轻柴油几乎无区别,与-10#军用柴油相比略有下降;使用B20时,发动机动力性与0#轻柴油、-10#军用柴油相比稍有下降,油耗略有增加。总体来看,在不改变发动机结构情况下,调和橡胶籽生物柴油B5、B20可以替代0#轻柴油。     

降低燃用生物柴油NOx排放量的分析

在YL4102型柴油机上分别燃用生物柴油、石化柴油、生物柴油和石化柴油的混合物测定NOx的排放情况,并对降低NOx排放量的措施进行了研究。结果表明,适当推迟喷油提前角会降低NOx的排放,在满负荷范围时,当喷油提前角为10°CA左右时NOx排放降低30％左右。燃用乳化生物柴油可降低NOx的排放,随着乳化生物柴油中水的增加,NOx的排放迅速下降,当水的体积分数为30％时,NOx排放降低40％左右。     

二叔丁基过氧化物对生物柴油热解特性的影响

应用热重分析方法,研究二叔丁基过氧化物(DTBP)对地沟油生物柴油热解特性的影响。选取N2和O2作为反应气,温度从50℃升高至400℃,升温速率为20℃/min,绘制生物柴油样品的失重曲线和微商热重曲线,分析不同DTBP添加量的生物柴油热解过程的挥发特性和燃烧特性。结果表明:添加DTBP对生物柴油的挥发性影响较小;添加DTBP的生物柴油燃烧指数有所增加;DTBP能够有效促进燃料燃烧,使生物柴油具有更好的可燃性。     

Reliable identification of grapevine rootstock varieties using RAPD PCR on woody samples

Since grapevine ( Vitis spp .) rootstock material is being traded increasingly as disbudded woody material a lack of distinctive morphological features on such material necessitates an alternative and reliable means of identification. Methods described here were developed for rapid and efficient extraction of DNA from woody samples rich in phenolic compounds and polysaccharides, and for subsequent identification of varieties by RAPD PCR. Using these methods, and with the application of only one selected RAPD primer, we were able to differentiate sixteen rootstock varieties, including the seven varieties most commonly used in Germany. Problems commonly encountered with reproducibility of RAPD patterns were avoided by choosing primers with a dinucleotide sequence and a high G/C content that allowed a rather high annealing temperature of 45°C. Methods described here should also be useful for other horticultural crops, especially those with woody tissues rich in phenolic compounds and polysaccharides.     

An internet compendium of analytical methods and spectroscopic information for monomers and additives used in food packaging plastics

An internet website (http://cpf.jrc.it/smt/) has been produced as a means of dissemination of methods of analysis and supporting spectroscopic information on monomers and additives used for food contact materials (principally packaging). The site which is aimed primarily at assisting food control laboratories in the European Union contains analytical information on monomers, starting substances and additives used in the manufacture of plastics materials. A searchable index is provided giving PM and CAS numbers for each of 255 substances. For each substance a data sheet gives regulatory information, chemical structures, physico-chemical information and background information on the use of the substance in particular plastics, and the food packaging applications. For monomers and starting substances (155 compounds) the infra-red and mass spectra are provided, and for additives (100 compounds); additionally proton NMR are available for about 50% of the entries. Where analytical methods have been developed for determining these substances as residual amounts in plastics or as trace amounts in food simulants these methods are also on the website. All information is provided in portable document file (PDF) format which means that high quality copies can be readily printed, using freely available Adobe Acrobat Reader software. The website will in future be maintained and up-dated by the European Commission's Joint Research Centre (JRC) as new substances are authorized for use by the European Commission (DG-ENTR formerly DGIII). Where analytical laboratories (food control or other) require reference substances these can be obtained free-ofcharge from a reference collection housed at the JRC and maintained in conjunction with this website compendium.     

Aroma characterization of various apricot varieties using headspace–solid phase microextraction combined with gas chromatography–mass spectrometry and gas chromatography–olfactometry

The characterization of the aromatic profile of several apricot cultivars with molecular tracers in order to obtain objective data concerning the aromatic quality of this fruit was undertaken using headspace–solid phase microextraction (HS–SPME). Six apricot cultivars were selected according to their organoleptic characteristics: Iranien, Orangered, Goldrich, Hargrand, Rouge du Roussillon and A4025. The aromatic intensity of these varieties measured by HS–SPME–Olfactometry were defined and classified according to the presence and the intensity of grassy, fruity and apricot like notes. In the six varieties, 23 common volatile compounds were identified by HS–SPME–GC–MS. Finally, 10 compounds, ethyl acetate, hexyl acetate, limonene, β-cyclocitral, γ-decalactone, 6-methyl-5-hepten-2-one, linalool, β-ionone, menthone and (E)-hexen-2-al were recognized by HS–SPME–GC–O as responsible of the aromatic notes involved in apricot aroma and considered as molecular tracers of apricot aromatic quality which could be utilized to discriminate apricot varieties.     

Tests of potential functional barriers for laminated multilayer food packages. Part I: Low molecular weight permeants

The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 μm-thick oriented PP) into the food simulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.     

Analysis of benzo[a]pyrene in spiked fatty foods by second derivative synchronous spectrofluorimetry after microwave-assisted treatment of samples

A simple, rapid and inexpensive method has been developed for the determination of benzo[a     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.     

Detection of adulteration of locust bean gum with guar gum by capillary electrophoresis and polarized light microscopy

Capillary electrophoresis (CE) and polarized light microscopy (PLM) were utilized in the detection of the adulteration of locust bean gum with guar gum. For CE analyses, standards of locust bean and guar gums were extracted with 30% CH₃CN, removing the residual proteins from the gum matrix. A 8.75 mM NaH₂PO₄-20.6 mM Na₂B₄O₇ buffer, pH 9, was used to separate these proteins and to identify marker proteins that were present in the guar gum. These markers did not co-migrate with components in the extracts of mechanically processed locust bean gum, and are used as indicators of adulteration. Using PLM with toluidine blue and iodine staining techniques, unadulterated locust bean gum samples were distinguished from mixed samples through the differential staining of components in locust bean versus guar and tara gums. These experiments in the use of CE and PLM provide orthogonal and complementary methods for the verification of 'true' positives and the elimination of 'false' positives.     

Announcing a new international peer-reviewed journal:Food Science and Human Wellness now accepting manuscript submission in English

<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of the     

Chinese CTP Market

According to Printing and Printing Equipment Industries Association of China（PEIAC）＇s statistics to the plate manufucturer in China, in 2013, the actual offset plate production has reached 346 million square meters in China. Among them, the CTP production volume was 245 million square meters, up by 11% than that of last year; the total sales of the CTP plate was 239 million square meters, up by 13%.