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1.
《International Journal of Hydrogen Energy》2022,47(5):3248-3265
A novel solid oxide fuel cell (SOFC) multigeneration system fueled by biogas derived from agricultural waste (maize silage) is designed and analyzed from the view point of energy and exergy analysis. The system is proposed in order to limit the greenhouse gas emissions as it uses a renewable energy source as a fuel. Electricity, domestic hot water, hydrogen and cooling load are produced simultaneously by the system. The system includes a solid oxide fuel cell; which is the primary mover, a biogas digester subsystem, a cascaded closed loop organic Rankine cycle, a single effect LiBr-water absorption refrigeration cycle, and a proton exchange membrane electrolyzer subsystem. The proposed cascaded closed-loop ORC cycle is considered as one of the advanced heat recovery technologies that significantly improve thermal efficiency of integrated systems. The thermal performance of the proposed system is observed to be higher in comparison to the simple ORC and the recuperated ORC cycles. The integration of a splitter to govern the flue gas separation ratio is also introduced in this study to cater for particular needs/demands. The separation ratio can be used to vary the cooling load or the additional power supplied by the ORC to the system. It is deduced that net electrical power, cooling load, heating capacity of the domestic hot water and total energy and exergy efficiency are 789.7 kW, 317.3 kW, 65.75 kW, 69.86% and 47.4% respectively under integral design conditions. Using a parametric approach, the effects of main parameters on the output of the device are analyzed. Current density is an important parameter for system performance. Increasing the current density leads to increased power produced by the system, decreased exergy efficiency in the system and increased energy efficiency. After-burner, air and fuel heat exchangers are observed to have the highest exergy destruction rates. Lower current density values are desirable for better exergy-based sustainability from the exergetic environmental impact assessment. Higher current density values have negative effect on the environment. 相似文献
2.
《Journal of dairy science》2022,105(2):1768-1787
Newborn calves rely on lipids in colostrum for energy and immune function. The lipid concentration in colostrum, however, is highly variable, and little is known about its composition and maternal factors that influence its composition. The first objective was to measure plasma lipid composition of multiparous cows at 35 d before calving (BC; 35 ± 3 d; ± standard deviation) and 7 d BC (7 ± 2 d), their colostrum, and serum lipid composition of calves (24 h after birth) using multiple reaction monitoring profiling, which is an exploratory and highly sensitive lipidomic analysis method that screens lipids based on chemical functionality. Second, data were analyzed to determine if there were relationships between circulating lipids in the cow, colostrum lipids, and calf serum lipids. Third, relationships between markers of metabolic status of the cows and circulating and colostrum lipids were analyzed with correlation analysis. Blood was sampled and plasma prepared from multiparous cows (n = 16) at 35 and 7 d BC. Within 3 h of parturition, colostrum was collected from cows and fed to her calf. Calves received another feeding of colostrum within 12 h after birth and a serum sample was collected from each calf 24 h after the first feeding of colostrum. The metabolic status of cows was evaluated using insulin, glucose, and nonesterified fatty acid area under the curve in response to an intravenous glucose tolerance test performed at 3 wk BC. Lipids were extracted from plasma, colostrum, and calf serum and were analyzed using multiple reaction monitoring profiling. Concentration of lipids were calculated using spiked in standards and expressed as percent of lipids identified. Data were uploaded into MetaboAnalyst 5.0 for multivariate and univariate analysis. Principal component analysis indicated that circulating lipids in the cow and calf were distinct from lipids in colostrum. Phosphatidylglycerol (PG) concentration was greater in colostrum and calf serum than in cow plasma, with 23 of the 24 PG found in colostrum also found in calf serum. In response to intravenous glucose tolerance test in late gestation, nonesterified fatty acid area under the curve was positively related to total triacylglycerols lipids in 7 d BC plasma (r = 0.63) but negatively related to total membrane lipids in colostrum (r = ?0.55). Thus, the metabolic status of the dam influences circulating lipids and colostrum lipid content. Moreover, the circulating lipidome of the cow and calf are similar to one another and distinct from the colostrum lipidome, except for PG, where it appears that colostrum serves as the source for PG in the calf's circulation. 相似文献
3.
In the electro-deoxidation process, carbon parasitic reaction (CO32- + 4e-=C + 3O2-) usually occurs when using carbon materials as the anode, which leads to increase of the carbon content in the final metal and decrease of the current efficiency of the process. The aim of this work is to reduce the negative effect of carbon parasitic reaction on the electrolysis process by adjusting anode current density. The results indicate that lower graphite anode area can achieve higher current density, which is helpful to increase the nucleation site of CO2 bubbles. Most of CO2 would be released from the anode instead of dissolution in the molten CaCl2 and reacting with O2- to form CO32-, thus decreasing the carbon parasitic reaction of the process. Furthermore, the results of the compared experiments show that when the anode area decreases from 172.78 to 4.99 cm2, CO2 concentration in the released gases increases significantly, the carbon mass content in the final metal product decreased from 1.09% to 0.13%, and the current efficiency increased from 6.65% to 36.50%. This study determined a suitable anode current density range for reducing carbon parasitic reaction and provides a valuable reference for the selection of the anode in the electrolysis process. 相似文献
4.
能源计量与节能监测、能源审计、能源统计、能源利用状况分析是用能单位能源管理和节能工作的基础。通过对本市部分火力发电企业的现场调研,针对性地提出改进建议,以期帮助用能单位增强能源计量在节能减排工作中的有效性。 相似文献
5.
以2018年58家氯碱企业供电、整流技术与设备现状调查数据为依据,阐述了国内氯碱企业中快速熔断器的运行状况。调查数据中包括50家氯碱企业的快速熔断器的基本运行数据、投运时间及设备来源等。汇总了各企业在氯碱生产中使用快速熔断器时遇到的问题、发生的故障甚至酿成的生产事故及对氯碱生产造成的影响。并分析了事故发生的原因,提出了预防及解决措施,总结了事故处理经验,旨为氯碱生产提供参考依据。 相似文献
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燃料电池车以其能量转化效率高、绿色环保、噪音低等优点,被认为是替代传统化石能源汽车最有前景的新能源汽车。目前车用燃料电池的工作温度一般都低于80℃,低温的工作环境使其面临着诸多问题,如复杂的水管理和CO中毒等。通过提高质子交换膜燃料电池(PEMFC)的工作温度可以缓解这些问题,提高燃料电池的性能。然而,高温的工作环境也会对燃料电池带来诸多挑战,如膜脱水、催化剂团聚、冷启动速度缓慢等。要促进高温(90~120℃)车用燃料电池的快速发展,需要对其问题及解决方法进行分析。本文从电堆比功率、膜电极、双极板、进气方式、加湿方式等方面,介绍燃料电池的发展现状及存在的问题,包括Nafion膜和催化剂的热稳定问题、双极板的耐腐蚀问题、流道的气体分配问题、进气方式和加湿方式的优化以及冷启动问题。指出通过掺杂亲水性氧化物改善Nafion膜的高温性能;将Pt合金化及采用介孔炭提高催化剂的稳定性和电化学活性;镀层不锈钢金属双极板可以增强耐腐蚀性;3D流场等新型流场结构及提高进气温度、速度可以提高气体的均匀性;采用自增湿方式可以简化电堆结构等解决方法,以期对燃料电池车的进一步发展起到引导作用。 相似文献
8.
肉桂是我国特色经济林树种,我国肉桂种植面积和年产量均居世界首位。我国肉桂主要分布在两广地区,其中广西为14.9万hm2,广东为8.9万hm2,两地面积占全国肉桂分布总面积的95%以上。肉桂既是著名的香料又是传统的名贵中药,具有极高的经济价值,发展肉桂产业对于促进农民增收、维护健康中国有着重要的意义。本研究综述了肉桂资源量、分布情况及主要利用部位,介绍肉桂主要产品(如桂皮,桂枝,肉桂粉及肉桂油)及加工技术现状、产品质量控制及其分析检测方法,分析了产业未来的发展趋势,并提出了产业发展的对策和措施:加强肉桂标准化示范基地建设,提高优质资源供给能力;提高肉桂加工利用技术水平,延长产业链;培育肉桂龙头企业,提高产品市场竞争力。为我国肉桂特色资源加工利用产业的可持续发展提供一定的思路。 相似文献
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