Exergy and exergo-environmental analysis of a 660 MW supercritical coal-fired power plant

Journal of Thermal Analysis and Calorimetry - This paper presents the exergy and exergo-environmental analysis of the 660 MW supercritical coal-fired unit situated in western India. The...     

Exergy analysis on eco-industrial systems

1 Introduction Ecological industry is to realize the harmony de- velopment between economy and environment by planning industrial systems according to material cy- cle in the natural ecological system. It got grown rap- idly both in theories and practices since the 1990s[1,2]. Many countries including China have applied indus- trial ecology to industrial practices. It is deeply recog- nized that developing ecological industry and advanc- ing on a new industrialization mode is an important way…     

Energy,Exergy analysis and performance evaluation of a vacuum evaporator for solar thermal power plant Zero Liquid Discharge Systems

Journal of Thermal Analysis and Calorimetry - Water scarcity and environmental impacts of blowdown within steam power plants are among the important growing concerns. In order to solve these...     

Exergy analysis and experimental study of a vapor compression refrigeration cycle

This article presents a detailed experimental analysis of 2TR (ton of refrigeration) vapor compression refrigeration cycle for different percentage of refrigerant charge using exergy analysis. An experimental setup has been developed and evaluated on different operating conditions using a test rig having R22 as working fluid. The coefficient of performance, exergy destruction, and exergetic efficiency for variable quantity of refrigerant has been calculated. The present investigation has been done by using 2TR window air conditioner and the results indicate that the losses in the compressor are more pronounced, while the losses in the condenser are less pronounced as compared to other components, i.e., evaporator and expansion device. The total exergy destruction is highest when the system is 100% charged, whereas it is found to be least when the system is 25% charged.     

Thermodynamic and thermoeconomic analyses and energetic and exergetic optimization of a turbojet engine

Journal of Thermal Analysis and Calorimetry - In this study, a thermal model for a turbojet engine is proposed. Besides the engine’s performance, the cost flow rate of each component is...     

防晒霜紫外线透光率测定及防晒效果探析

建立了防晒类化妆品中常用15种防晒剂的高效液相色谱/三重四极杆质谱联用分析方法和样品前处理方法. 样品中加入1 mL无水乙醇,用乙腈︰水（体积比4∶1）定容,超声提取后,QuEChERS柱净化,0 ℃下10000 r/min离心10 min,以含0.1%甲酸的乙腈溶液-含0.1%甲酸的2 mmol/L乙酸铵溶液为流动相,梯度洗脱,C18（2.1 mm×50 mm, 1.8 μm）色谱柱分离,多反应监测（MRM）正离子模式扫描,外标法定量. 结果显示：15种防晒剂在一定浓度范围内呈良好线性关系,相关系数均大于0.99,方法检出限为10~50 μg/kg. 方法平均回收率为68.4%~84.2%. 相对标准偏差（RSD）为1.7%~9.0%. 方法可用于防晒剂的检测,灵敏度高,重现性好,具有良好适应性.     

Exergy analysis of a plate heat exchanger with a new geometric design

Journal of Thermal Analysis and Calorimetry - In the current study, a plate heat exchanger with a novel geometry is investigated in which the cross section is not uniform as in conventional ones....     

Microchip analysis of plant glucosinolates

We describe a new and selective analytical method for the separation and quantitation of plant glucosinolates. The new method, which utilizes microchip CE (micro-CE) with fluorescence detection, circumvents the multistep procedures characteristic of conventional methods. Glucosinolates form charge transfer complexes with the xanthene dyes phloxine-B and eosin-B. The glucosinolates-phloxine-B complex cannot be excited at 470 nm. Thus, the decrease in peak intensity of phloxine-B after complex formation is used to quantitatively measure total glucosinolates in Arabidopsis thaliana seeds. For qualitative analysis, complex formation with eosin-B is used. The sensitivity of eosin-B detection at excitation/emission 470 nm/540 nm was low. However, sensitivity increased following complex formation with sinigrin (> or =3 microg/mL). A batch-learning, self-organizing map was applied to visualize and organize analytical data into 2-D matrix with similar and related data clustered together or near each other. This organized matrix was used to optimize electrophoretic conditions for the analysis. This study suggests potential applications of micro-CE in plant metabolomics analyses without use of labeling fluorophores.     

Thermogravimetric analysis of Mediterranean plant species

Twelve dominant Mediterranean plant species were subjected to thermogravimetric analysis (TGA) in air medium, in order to study their thermal degradation process and assess their potential combustibility as natural fuels. Statistically significant differences were observed among the values of the pyrolytic parameters of the species analyzed. The mean volatilization rate values resulted in meaningful ranking of the species into vegetation types of similar combustibility, as verified by observations during actual wildfires. The use of TGA as a method for assessing the combustibility of individual plant species seems justified.     

Comparative analysis of plant lycopene cyclases

Carotenoids are essential isoprenoid pigments produced by plants, algae, fungi and bacteria. Lycopene cyclase (LYC) commonly cyclize carotenoids, which is an important branching step in the carotenogenesis, at one or both end of the backbone. Plants have two types of LYC (β-LCY and ϵ-LCY). In this study, plant LYCs were analyzed. Based on domain analysis, all LYCs accommodate lycopene cyclase domain (Pf05834). Furthermore, motif analysis indicated that motifs were conserved among the plants. On the basis of phylogenetic analysis, β-LCYs and ϵ-LCYs were classified in β and ϵ groups. Monocot and dicot plants separated from each other in the phylogenetic tree. Subsequently, Oryza sativa Japonica Group and Zea mays of LYCs as monocot plants and Vitis vinifera and Solanum lycopersicum of LYCs as dicot plants were analyzed. According to nucleotide diversity analysis of β-LCY and ϵ-LCY genes, nucleotide diversities were found to be π: 0.30 and π: 0.25, respectively. The result highlighted β-LCY genes showed higher nucleotide diversity than ϵ-LCY genes. LYCs interacting genes and their co-expression partners were also predicted using String server. The obtained data suggested the importance of LYCs in carotenoid metabolism. 3D modeling revealed that depicted structures were similar in O. sativa, Z mays, S. lycopersicum, and V. vinifera β-LCYs and ϵ-LCYs. Likewise, the predicted binding sites were highly similar between O. sativa, Z mays, S. lycopersicum, and V. vinifera LCYs. Most importantly, analysis elucidated the V/IXGXGXXGXXXA motif for both type of LYC (β-LCY and ϵ-LCY). This motif related to Rossmann fold domain and probably provides a flat platform for binding of FAD in O. sativa, Z mays, S. lycopersicum, and V. vinifera β-LCYs and ϵ-LCYs with conserved structure. In addition to lycopene cyclase domain, the V/IXGXGXXGXXXA motif can be used for exploring LYCs proteins and to annotate the function of unknown proteins containing lycopene cyclase domain. Overall results indicated that a high degree of conserved signature were observed in plant LYCs.     

Evaluation of the Chemical Exergy of Fuels and Petroleum Fractions

A correlation formula to estimate chemical exergies of oil fractions and fuel mixtures from enthalpy of combustion and atomic composition is developed. Heat capacity ofa mixture of 10 hydrocarbons was measured in the range 5–290 K. It was shown that contribution of entropy of mixing to exergy of typical oil fractions is about –0.11% in the approximation of ideal solution, and about –0.18% for a real solution. This revised version was published online in July 2006 with corrections to the Cover Date.     

Exergy analysis of a pervaporation system and its combination with a distillation column based on an energy utilization diagram

Based on an energy utilization diagram, energy and exergy analysis of a pervaporation system is performed by taking three subsystems into account, supply of heat, pervaporation, and suction. By this single diagram, the energy balance, the exergy loss in each subsystem, and the strength of forces driving processes can be disclosed. Energy transformation in the pervaporation system and the effects of manipulating variables are clarified by comparison with a distillation system. The energy utilization diagram is also applied to examine a system in which a pervaporator and a distillation column are combined. It is shown that separation by pervaporation is quite effective from the viewpoint of exergy, especially when the pervaporation system can proceed by the difference between the temperature of the feed liquid and that of the cooling water only. This is because in this case low-grade energy is utilized completely.     

全二维气相色谱-质谱法检测天然奶油和人造奶油中的脂肪酸

建立了天然奶油和人造奶油中37种脂肪酸的全二维气相色谱-质谱检测方法。样品经甲苯提取、乙酰氯-甲醇（1∶9,v/v）溶液甲酯化衍生后,以DB-5柱（30 m×0.25 mm×0.25 μm）为一维柱、BPX-50柱（2.5 m×0.1 mm×0.25 μm）为二维柱进行分离。升温程序为50℃保持2 min,以20℃/min升温至180℃,以2.5℃/min升温至250℃,以3℃/min升温至300℃,保持5 min。在调制周期为5 s、扫描范围为m/z 40~385的条件下,奶油中37种脂肪酸得到了有效分离和准确测定。将该方法应用于实际样品的分析,检测结果比传统的气相色谱法更灵敏,脂肪酸组成也更丰富,可有效鉴别不同种类奶油的差异成分。该方法不仅为奶油中脂肪酸成分分析提供了新的技术手段,同时在保障奶油的质量安全、鉴别掺假伪劣等过程中发挥重要作用。     

Qualitative and quantitative chromatographic analysis of plant leaf waxes

Summary Plant leaf waxes can be characterised by HPLC eitherin toto or after separation into acidic and neutral fractions using DEAE Sephadex A-25. Group separation of acidic fraction components is easy using reversed phase systems; this method is also applicable but not recommended for the characterisation of unfractionated wax samples. Separation and quantitation of wax neutral fractions is easier by adsorption HPLC systems but solvent composition is critical and normally involves use of tetrahydrofuran. The replacement of a sample loop of the injector by a short column permits injection of larger volumes as well as separate elution of the most polar components. Examples are presented using mass and UV detectors as well as gravimetric analysis of wax from several plant species.Presented at the 14th International Symposium on Chromatography London, September, 1982     

TG and NMR analysis of commercial plant oil seeds

Experiments were performed to obtain rapid quantitative information on the water and oil content, and on the ash residue of some plant oil seeds, all of considerable commercial interest.

TG, DTG and low-resolution NMR were used as the analytical techniques.     

Exergy analysis of vapor compression refrigeration system using R450A as a replacement of R134a

This paper experimentally investigated exergetic performance analysis of vapor compression refrigeration system using R450a as a replacement for R134a at different evaporator and condenser temperatures within controlled environmental conditions. The exergetic performance analysis of the vapor compression refrigeration system with test parameters including efficiency defects in the components, total irreversibility, and exergy efficiency of the refrigeration system was performed. Findings showed that the total irreversibility and exergy efficiency of the vapor compression refrigeration system using R450A refrigerant were lower and higher than R134a by about 15.25–27.32% and 10.07–130.93%, respectively. However, the efficiency defect in the condenser, compressor, and evaporator of the R450A refrigeration system was lower than R134a by about 16.99–26.08%, 5.03–20.11%, and 1.85–15.85%, respectively. Conversely, efficiency defect in the capillary tube of the R450A refrigeration system was higher than R134a by about 14.66–78.97% under similar operating conditions. Overall, it was found that the most efficient component was the evaporator, and the least efficient component was the compressor for both refrigerants.

     

Neutron activation analysis of medicinal plant extracts

Instrumental neutron activation analysis was applied to the determination of the elements Br, Ca, Cl, Cs, Fe, K, La, Mg, Mn, Na, Rb and Zn in medicinal extracts obtained fromCentella asiatica, Citrus aurantium L., Achyrolcline satureoides DC, Casearia sylvestris, Solano lycocarpum, Zingiber officinale Roscoe, Solidago microglossa andStryphnondedron barbatiman plants. The elements Hg and Se were determined using radiochemical separation by means of retention of Se in HMD inorganic exchanger and solvent extraction of Hg by bismuth diethyldithiocarbamate solution. Precision and accuracy of the results were evaluated by analyzing biological reference materials. The therapeutic action of some elements found in plant extracts analyzed is briefly discussed.     

Preprocessing and exploratory analysis of chromatographic profiles of plant extracts

The characterization of herbal extracts to compare samples from different origin is important for robust production and quality control strategies. This characterization is now mainly performed by analysis of selected marker compounds. Metabolic fingerprinting of full metabolite profiles of plant extracts aims at a more rapid and thorough screening or classification of plant material. We will show that HPLC is an appropriate technique for metabolic fingerprinting of secondary metabolites, given that adequate preprocessing of raw profiles is performed. Additional variation, which results from sample preparation and changing measurement conditions, usually obscures the information of interest in these raw profiles. This paper illustrates the importance of preprocessing of chromatographic fingerprinting data. Different alignment methods are discussed as well as the influence of normalization. Weighted principal component analysis is introduced as a valuable alternative to autoscaling of data. LC-UV data on Willow (Salix sp.) extracts is used to evaluate these preprocessing methods and their influence on exploratory data analysis.     

毛细管电泳法同时分析水、乳、膏类化妆品中5种有机酸

建立了毛细管电泳同时分析5种有机酸的间接紫外检测法。优化了背景电解质溶液中表面活性剂十四烷基三甲基溴化铵（TTAB）的浓度和溶液pH。优化后的电泳分析条件如下：含0.4 mmol/L TTAB的15 mmol/L邻苯二甲酸氢钾溶液为背景电解质（pH 5.6）；分离电压-15 kV；检测波长254 nm；分离温度25℃；进样压力5 kPa；进样时间5 s。在此条件下，可在6 min内完成5种有机酸的同时分离检测，线性范围为甲酸15~600 mg/L、苹果酸30~800 mg/L、柠檬酸20~700 mg/L、乙醇酸40~500 mg/L和乳酸30~5000 mg/L，线性相关系数为0.9983~0.9998；检出限为0.1~2.0 μg/g。该方法可用于检测水状、乳状、膏状3类化妆品中的5种有机酸。在3个加标水平下，有机酸分析的回收率为95.0%~101.6%，RSD在2.0%以内。该方法操作简单，分析快速，安全环保，灵敏度高，重现性好，有望用于化妆品生产和保存过程中有机酸的监测。