硫与间氯苯腙对海水绿藻Platymonas subcordiformis光照产氢特性的影响

对数生长后期海水绿藻Platymonas subcordiformis具有较高氢酶活性,分别采用培养基中无硫和添加解偶联剂CCCP的方法研究其光照产氢特征.结果表明:无硫连续光照期间,PSⅡ保持较高放氧活性,不能诱导氢酶表达进行光照产氢;厌氧暗诱导32h后,加入5、10、15和20μmol/L的解偶联剂CCCP后光照,PSⅡ光化学活性和光合放氧能力明显被抑制,藻液体系保持厌氧状态,能够持续光照产氢12h以上,光照产氢量分别为21.8、23.0、22.5和16.0μmol/mg Chl;合适浓度的CCCP能够促进绿藻直接光照产氢,但光照产氢量和产氢速率较低.     

培养基对海水绿藻Platymonas subcordiformis生长和无硫光照产氢的影响

研究了基于淡水绿藻Chlamydomona reinhardtii培养基TAP的优化培养基(OM)和传统康维方培养基(TM)对海水绿藻Platymonas subcordiformis培养和无硫光照产氢的影响.研究结果表明OM培养6～8d就能达到对数生长后期,藻密度为(1.80～2.00)×10~6 cells·mL~(-1),而TM需要18～20d;OM培养藻细胞对数生长后期叶绿素、淀粉和蛋白含量分别为10.74、149.50和213.00μg·mL~(-1),均高于TM培养的藻细胞.OM培养藻细胞的呼吸耗氧速率明显高于TM培养的藻细胞.悬浮在OM-S中藻细胞的PSⅡ光化学活性被明显抑制,能够产生2.01μmol H_2·mg~(-1)Chl;而悬浮在TM-S中藻细胞PSⅡ光化学活性保持在0.19以上,不能诱导氢酶表达产生氢气.     

链霉素对蛋白核小球藻Chlorella pyrenoidosa产氢及其生长的影响

以蛋白核小球藻Chlorella pyrenoidosa为材料,研究不同链霉素浓度对其生长及其产氢过程的影响。结果表明,添加600 mg/L的链霉素对蛋白核小球藻的产氢具有最大促进作用,产氢时间可持续8 d,比对照组延长近6 d,总产氢量为354.54μL/mg,分别是对照组、200 mg/L和1 000 mg/L试验组的18.44,5.85和1.35倍;通过比较不同条件下蛋白核小球藻的光合及生长状况,证实链霉素明显抑制了蛋白核小球藻的光合放氧,对藻细胞产氢后期的生长也有一定抑制作用。     

研究光合生物氢代谢的高灵敏度气相色谱法

本文报道了一种高灵敏度的测氢气相色谱法和几种不同类型光合生物放氢和吸氢活性的初步测定结果。 采用新型碳多孔微球TDX-02作为分离柱固定相,选用ST-04型色谱仪,并用高纯氮作载气,当进样1毫升气体样品时,可检测到0.2ppm(V/V)(相当于1×10~(-11)克分子)的氢气。 测定满江红-鱼腥藻共生体的放氢活性,需在Ar-C_2H_2-CO气相中静止光保温。不同种的满江红在不同气相中放氢活性有差别。兰藻在氩气中振荡光保温时,显示的放氢活性最高。绿藻、红藻和褐藻在厌氧暗适应后,有甲基紫精和连二亚硫酸钠存在下暗保温,能检测到其中氢化酶催化的放氢活性。吸氢活性的检测,需有适量氧和氢的存在。     

光合细菌小分子酸醇产氢试验研究

以光合产氢混合菌群为研究对象,研究了光合细菌在乙酸、乙醇、乳酸、丁酸几种小分子脂肪酸条件下菌体的生长和产氢特性,详细考察了乙酸和丁酸对光合产氢细菌生长和产氢的影响.研究发现,乙酸、丁酸既是光合细菌良好的生长碳源,也是高效氢供体,光合细菌在乙酸和丁酸条件下产氢率分别达到2.05和2.81molH2/mol.光合细菌以乙酸和丁酸产氢时,乙酸和丁酸的最佳添加浓度均为40mmol/L;光合细菌在乳酸条件下有较高的生长活性,但乳酸并不是光合细菌高效氢供体,光合细菌在乳酸条件下产氢活性较低;乙醇既不是光合细菌良好生长碳源,也不是高效氢供体,乙醇对光合细菌的生长和产氢均有较强的抑制作用.     

光照波长对HAU-M1光合菌群产氢影响的研究

以菌体干重、比产氢速率、pH值和葡萄糖浓度等为主要实验指标,研究不同波长光源对HAU-M1光合菌群生长及光发酵产氢的影响,并用产氢动力学对光合菌群产氢进行分析。结果表明:相同光照强度下,相对于连续全光谱,492～622 nm波长光照能促进光合菌群生长及产氢;492～577 nm波长下菌群生长及产氢效果最佳,菌体干重达到0.72 g/L,比产氢速率达到11.16 mL/(g DCW·h),相比对照组提高25%。     

莱茵衣藻和根瘤菌共培养提高产氢条件的优化

将莱茵衣藻(Chlamydomonas reinhardtii)以不同比例与日本慢生大豆根瘤菌(Bradyrhizobium japonicum)混合,在不同光照条件下进行产氢培养,以确定产氢的最优条件和探索产氢提高的机理。结果表明:藻菌共培养的最优产氢条件为25℃、光照200μE/(m~2·s)、生长至饱和期的菌和藻体积比为1∶80,产氢量最大,约为272μmol/(mg Chl),是对照组的17.0倍。藻菌共培养提高产氢量的主要原因是体系中O_2浓度的降低使氢化酶活性提高以及衣藻生物量的增加。     

固定化光合细菌利用低分子有机酸的产氢特性

通过固定化光合细菌对低分子有机酸进行了光合产氢的批式试验研究.利用修正的Gompertz方程进行产氢动力学分析,并且对产氢过程中pH变化、有机酸的氢转化率以及有机酸初始浓度对产氢的影响等进行了分析.结果表明固定化能提高产氢率,以海藻酸钠为固定化载体的产氢效果最佳.同时发现有机酸产氢存在最佳初始浓度,其中乳酸产氢的最佳初始浓度为0.049mol/L,对于乙酸、丙酸和丁酸这3种小分子羧酸,其最佳初始浓度的大小随着有机酸碳原子数的增加而减小,即乙酸(0.043mol/L)丙酸(0.029mol/L)丁酸(0.022mol/L).乙酸的最大氢转化率最高,达到65.3%.浓度对氢气含量没有影响,而对于乙酸、丙酸和丁酸,氢气含量随着有机酸碳原子数的增加而增大.     

混合菌种利用淀粉在光照及黑暗条件下的产氢

进行了混合菌种利用淀粉进行光反应和暗反应的产氢对比试验.结果发现光合反应的产氢率以及产氢速率均高于暗反应,但产氢时间滞后于暗反应.对反应的菌液进行了DNA提取、纯化以及PCR扩增,通过对DGGE图谱分析,发现光反应和暗反应的样品条带在数量和亮度上都存在一定差异,暗反应条件下产氢的优势菌群要略多于光合反应的菌群.随着淀粉浓度的增加,光合反应和暗反应的产氢总量均增大,但产氢率降低,其中光合反应的降低尤为明显,从2g/L淀粉浓度时的9.8mmol H2/g淀粉降低到40g/L淀粉浓度时的3.3mmol H2/g淀粉,产氢率降低了66%,而暗反应产氢率降低了43%.光合反应的尾液中,丁酸含量最高,而暗反应的尾液中,乙酸含量最高.     

超微玉米秸秆光合产氢响应面法优化研究

为了优化超微生物质秸秆产氢工艺,提高产氢能力,对影响超微生物质秸秆光合产氢的主要因素进行正交试验研究,获得温度、光照、底物浓度、接种量四因素与产氢量的数学模型,并进行两因素的交互效应分析,发现各因素的边际产量均减小,温度对边际产量的影响最大,温度越大,边际产量越低;在交互作用中,温度、光照的交互作用最大,其次是温度和底物浓度;采用Matlab软件编程计算得出产氢量最高时各因素最优组合为温度33℃,光照强度3500lx,接种量25%,底物浓度55g/L。     

Metabolomics of photobiological hydrogen production induced by CCCP in Chlamydomonas reinhardtii

The green alga Chlamydomonas reinhardtii can produce hydrogen gas (H₂) in the presence of the proton uncoupler carbonyl cyanide m-chlorophenyl hydrazone (CCCP). The addition of 15 μM CCCP to the algal cultures led to 13-fold increase in H₂ photoproduction compared to the control cultures without CCCP treatment. CCCP completely inhibited the photochemical activity of photosystem (PS) II under illumination. In order to better understand metabolic conditions necessary for sustained H₂ production, we have used gas chromatography coupled to time-of-flight mass spectrometry (GC-TOF) for metabolomics analysis that is independent of nutritional stress, specifically, sulfur deprivation, which had been used previously to induce H₂ photoproduction. Even 10 min after addition of CCCP, metabolites from many metabolic modules were found drastically decreased, including levels of free amino acids, unsaturated free fatty acids and nucleotides. During prolonged CCCP exposure H₂ production was found to be stable for at least 12 h with a continued increase in levels of free fatty acids. These results indicate that CCCP might become a useful treatment for production of biohydrogen in reactors. The increase in fatty acid production might then be a useful addition for production of carbon-derived biofuels.     

Characterization of hydrogen production by Platymonas Subcordiformis in torus photobioreactor

Platymonas subcordiformis, a marine green alga, was demonstrated to photo-biologically produce hydrogen when regulated by a kind of proton uncoupler CCCP (Carbonyl Cyanide m-Chlorophenylhydrazone). In this paper, hydrogen production experiments by P. subcordiformis were carried out in a torus photobioreactor equipped with a mass spectrometer and other necessary sensors so that instantaneous gas components could be measured and other successive physiological states could be well recorded.     

Ash-forming elements in four Scandinavian wood species. Part 1: Summer harvest

Woody biomass in Finland and Sweden comprises mainly four wood species: spruce, pine, birch and aspen. To study the ash, which may cause problems for the combustion device, one tree of each species were cut down and prepared for comparisons with fuel samples. Well-defined samples of wood, bark and foliage were analyzed on 11 ash-forming elements: Si, Al, Fe, Ca, Mg, Mn, Na, K, P, S and Cl. The ash content in the wood tissues (0.2–0.7%) was low compared to the ash content in the bark tissues (1.9–6.4%) and the foliage (2.4–7.7%). The woods’ content of ash-forming elements was consequently low; the highest contents were of Ca (410–1340 ppm) and K (200–1310), followed by Mg (70–290), Mn (15–240) and P (0–350). Present in the wood was also Si (50–190), S (50–200) and Cl (30–110). The bark tissues showed much higher element contents; Ca (4800–19,100 ppm) and K (1600–6400) were the dominating elements, followed by Mg (210–2400), P (210–1200), Mn (110–1100) and S (310–750), but the Cl contents (40–330) were only moderately higher in the bark than in the wood. The young foliage (shoots and deciduous leaves) had the highest K (7100–25,000 ppm), P (1600–5300) and S (1100–2600) contents of all tissues, while the shoots of spruce had the highest Cl contents (820–1360) and its needles the highest Si content (5000–11,300). This paper presented a new approach in fuel characterization: the method excludes the presence of impurities, and focus on different categories of plant tissues. This made it possible to discuss the contents of ash element in a wide spectrum of fuel-types, which are of large importance for the energy production in Finland and Sweden.     

Contents in Volume 23,2014

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Performance assessment of some ice TES systems

In this paper, a performance assessment of four main types of ice storage techniques for space cooling purposes, namely ice slurry systems, ice-on-coil systems (both internal and external melt), and encapsulated ice systems is conducted. A detailed analysis, coupled with a case study based on the literature data, follows. The ice making techniques are compared on the basis of energy and exergy performance criteria including charging, discharging and storage efficiencies, which make up the ice storage and retrieval process. Losses due to heat leakage and irreversibilities from entropy generation are included. A vapor-compression refrigeration cycle with R134a as the working fluid provides the cooling load, while the analysis is performed in both a full storage and partial storage process, with comparisons between these two. In the case of full storage, the energy efficiencies associated with the charging and discharging processes are well over 98% in all cases, while the exergy efficiencies ranged from 46% to 76% for the charging cycle and 18% to 24% for the discharging cycle. For the partial storage systems, all energy and exergy efficiencies were slightly less than that for full storage, due to the increasing effect wall heat leakage has on the decreased storage volume and load. The results show that energy analyses alone do not provide much useful insight into system behavior, since the vast majority of losses in all processes are a result of entropy generation which results from system irreversibilities.     

NEXT GENERATION ENGINEERED MATERIALS FOR ULTRA SUPERCRITICAL STEAM TURBINES

正1 ABSTRACT To reduce the effect of global warming on our climate,the levels of CO2emissions should be reduced.One way to do this is to increase the efficiency of electricity production from fossil fuels.This will in turn reduce the amount of CO2emissions for a given power output.Using US practice for efficiency calculations,then a move from a typical US plant running at 37%efficiency to a 760℃/38.5 MPa(1 400/5 580 psi)plant running at 48%efficiency would reduce CO2emissions by 170kg/MW.hr or 25%.     

Effect of co-cultivation of Chlamydomonas reinhardtii with Azotobacter chroococcum on hydrogen production

Chlamydomonas reinhardtii cc124 and Azotobacter chroococcum bacteria were co-cultured with a series of volume ratios and under a variety of light densities to determine the optimal culture conditions and to investigate the mechanism by which co-cultivation improves H₂ yield. The results demonstrated that the optimal culture conditions for the highest H₂ production of the combined system were a 1:40 vol ratio of bacterial cultures to algal cultures under 200 μE m^?2 s^?1. Under these conditions, the maximal H₂ yield was 255 μmol mg^?1 Chl, which was approximately 15.9-fold of the control. The reasons for the improvement in H₂ yield included decreased O₂ content, enhanced algal growth, and increased H₂ase activity and starch content of the combined system.     

Aerodynamic performance effects of leading-edge geometry in gas-turbine blades

The purpose of this paper is to illustrate the advantages of the direct surface-curvature distribution blade-design method, originally proposed by Korakianitis, for the leading-edge design of turbine blades, and by extension for other types of airfoil shapes. The leading edge shape is critical in the blade design process, and it is quite difficult to completely control with inverse, semi-inverse or other direct-design methods. The blade-design method is briefly reviewed, and then the effort is concentrated on smoothly blending the leading edge shape (circle or ellipse, etc.) with the main part of the blade surface, in a manner that avoids leading-edge flow-disturbance and flow-separation regions. Specifically in the leading edge region we return to the second-order (parabolic) construction line coupled with a revised smoothing equation between the leading-edge shape and the main part of the blade. The Hodson–Dominy blade has been used as an example to show the ability of this blade-design method to remove leading-edge separation bubbles in gas turbine blades and other airfoil shapes that have very sharp changes in curvature near the leading edge. An additional gas turbine blade example has been used to illustrate the ability of this method to design leading edge shapes that avoid leading-edge separation bubbles at off-design conditions. This gas turbine blade example has inlet flow angle 0°, outlet flow angle −64.3°, and tangential lift coefficient 1.045, in a region of parameters where the leading edge shape is critical for the overall blade performance. Computed results at incidences of −10°,   −5°,   +5°,   +10° are used to illustrate the complete removal of leading edge flow-disturbance regions, thus minimizing the possibility of leading-edge separation bubbles, while concurrently minimizing the stagnation pressure drop from inlet to outlet. These results using two difficult example cases of leading edge geometries illustrate the superiority and utility of this blade-design method when compared with other direct or inverse blade-design methods.     

Natural-gas fueled spark-ignition (SI) and compression-ignition (CI) engine performance and emissions

Natural gas is a fossil fuel that has been used and investigated extensively for use in spark-ignition (SI) and compression-ignition (CI) engines. Compared with conventional gasoline engines, SI engines using natural gas can run at higher compression ratios, thus producing higher thermal efficiencies but also increased nitrogen oxide (NO_x) emissions, while producing lower emissions of carbon dioxide (CO₂), unburned hydrocarbons (HC) and carbon monoxide (CO). These engines also produce relatively less power than gasoline-fueled engines because of the convergence of one or more of three factors: a reduction in volumetric efficiency due to natural-gas injection in the intake manifold; the lower stoichiometric fuel/air ratio of natural gas compared to gasoline; and the lower equivalence ratio at which these engines may be run in order to reduce NO_x emissions. High NO_x emissions, especially at high loads, reduce with exhaust gas recirculation (EGR). However, EGR rates above a maximum value result in misfire and erratic engine operation. Hydrogen gas addition increases this EGR threshold significantly. In addition, hydrogen increases the flame speed of the natural gas-hydrogen mixture. Power levels can be increased with supercharging or turbocharging and intercooling. Natural gas is used to power CI engines via the dual-fuel mode, where a high-cetane fuel is injected along with the natural gas in order to provide a source of ignition for the charge. Thermal efficiency levels compared with normal diesel-fueled CI-engine operation are generally maintained with dual-fuel operation, and smoke levels are reduced significantly. At the same time, lower NO_x and CO₂ emissions, as well as higher HC and CO emissions compared with normal CI-engine operation at low and intermediate loads are recorded. These trends are caused by the low charge temperature and increased ignition delay, resulting in low combustion temperatures. Another factor is insufficient penetration and distribution of the pilot fuel in the charge, resulting in a lack of ignition centers. EGR admission at low and intermediate loads increases combustion temperatures, lowering unburned HC and CO emissions. Larger pilot fuel quantities at these load levels and hydrogen gas addition can also help increase combustion efficiency. Power output is lower at certain conditions than diesel-fueled engines, for reasons similar to those affecting power output of SI engines. In both cases the power output can be maintained with direct injection. Overall, natural gas can be used in both engine types; however further refinement and optimization of engines and fuel-injection systems is needed.