Search

: Microalgae (microscopic algae) have been the most promising renewable energy sources in freshwater and marine systems, due to the short growth cycles, high photosynthetic efficiency, environmental adaptability, and cellular lipid content. The cultivation cost of commercial microalgae is ever increasing in recent years. Particularly, chemical reagents are generally added to supply the nutrient sources for microalgae growth. Fortunately, human urine wastewater can be expected for microalgae cultivation, due to the abundant nitrogen, phosphorus, and trace elements for microalgae growth. Microalgae biomass can also be obtained to reduce the microalgae cultivation cost after purification, in order to realize the resource-based and high-value utilization of human urine wastewater. In the case of the microalgae growth temperature above 25.0 ℃, it is very important to explore the microalgae suitable for the low-temperature culture, in order to reduce the heating energy consumption of microalgae culture in winter in the north of China. In addition, human urine is also currently sterilized for microalgae cultivation, due to the high dilution times. More wastewater can be produced from a small amount of original human urine, leading to the high pretreatment cost of microalgae cultivation. In this study, a systematic investigation was carried out to clarify the effects of different temperatures (15.0, 17.5, 20.0, 22.5, and 25.0 ℃) on microalgae cultivation using human urine diluted by low times. The Chlorella pyrenoidosa and Chlorella sp were selected as the microalgae species. An artificial climate incubator was used under the human urine addition ratio of 40% and light intensity of 4000 lx for 14 days. The results showed that the two types of Chlorella grew better in the high concentration of human urine wastewater. The average removal ratios of the total nitrogen, ammonium nitrogen, total phosphorus, and chemical oxygen demand in the culture solution of Chlorella pyrenoidosa reached 78.02%, 79.59%, 79.31%, and 20.11%, respectively, where the maximum biomass dry weight reached 0.502 g/L. Comparatively, the average removal ratios of the total nitrogen, ammonium nitrogen, total phosphorus, and chemical oxygen demand in the culture solution of Chlorella sp. reached 87.90%, 89.55%, 89.29%, and 68.66%, respectively, where the maximum biomass dry weight reached 1.007g/L. There was an increase in biomass production and the total nitrogen, ammonium nitrogen, total phosphorus, and chemical oxygen demand removals of Chlorella pyrenoidosa and Chlorella sp., as the increase of temperature (P<0.05). The increasing rates were smaller under the temperature of higher than 20.0 ℃ than those lower than 20.0 ℃. Meanwhile, there was a strong influence of low temperature on the microalgae biomass, Chlorella protein, and chemical oxygen demand removal ratio than that on the contents of total nitrogen, ammonium nitrogen, and total phosphorus. Better adaptability of Chlorella sp. was also achieved in the human urine at low temperature than that of Chlorella pyrenoidosa, indicating more suitable for cultivation in the north of China. This finding can lay a theoretical foundation for the low-consumption and high-efficiency culture of microalgae in cold regions. [ABSTRACT FROM AUTHOR]

Water shortage and pollution are pushing to upgrade the conventional treatment of wastewater in the world. Microalgae-based Wastewater Treatment (WWT) has been widely expected to meet the new demand for the removal of nutrients and pathogens in recent years. However, a pretreatment process is normally required on the microalgae culture in wastewater from a cattle farm, such as settling, centrifugation, aeration, and dilution. It is a high demand for the potential microalgae culture substrates rich in nutrients, such as nitrogen and phosphorus, thereby reducing the cost of the pretreatment process for the better commercialization of the microalgae industry. Particularly, a large amount of breeding wastewater and manure have been rapidly produced in the livestock industry. In this study, the wastewater from a cattle farm was filtered by straw to cultivate the microalgae, in order to timely alleviate the loss of nutrients and environmental pollution. Kirchneriella obesa was selected as the experimental algae species. The mixture of straw-filtered wastewater and BG11 medium was also used as the microalgae culture medium. A systematic investigation was made on the effects of wastewater addition ratio, light intensity, photoperiod, and aeration on the dry weight of microalgae, as well as the ammonium (NH4 +-N), Total Phosphorus (TP), and Chemical Oxygen Demand (COD) removal rate. A Central Composite Design (CCD) with a single factor test was carried out to optimize the process parameters during cultivation. The results demonstrated promising potential of WWT in the nutrients removal from cattle farm wastewater. An optimal combination of process parameters for the cultivation was achieved as follows: 26 % of wastewater, light intensity of 9 028 lx, light time of 21.5 h, and the aeration intensity of 2.0 L/min. By the end of the 14-day culture period, the dry weight of Kirchneriella obesa reached 1.141 g/L under optimal conditions, where 99.65%, 99.15%, and 85.83% of NH4 +-N, TP, COD were removed, respectively. There were within 2% errors of the predicted and actual values for the response indexes. The dry weight of microalgae and COD removal rate were higher than predicted, indicating the credible optimization for the expected requirements. There was an outstanding interaction of wastewater addition ratio and light time on the dry weight of the algae. A strong correlation was also found between the wastewater addition ratio and aeration amount on the removal rate of NH4 +-N, TP, and COD in the culture solution of the algae. But the light intensity and light time had only interacted with the removal rate of TP. This finding can provide a theoretical reference to promote the industrial production of microalgae culture for the wastewater from a cattle farm. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Light interaction with plant tissue varies significantly in different components with the structural, chemical, and optical characteristics in most agro products at the microscale. In light-tissue interaction, the tissues can generally be treated as being primarily composed of absorption and scattering particles, and thus the light propagation through tissues can be simplified as mainly involving the process of photon interactions with the absorption and scattering particles. When entering the tissue, the light can be absorbed and/or scattered, represented by the absorption coefficient (μa) and reduced scattering coefficient (μ's), respectively. Quantification of optical properties (i.e., μa and μ's) can greatly contribute to clarifying the measured data, optimizing optical devices, and finally improving the quality and safety assessment of agro-products. Alternatively, spatial-frequency domain imaging (SFDI) has widely been used to measure the optical properties, and then to evaluate the quality/safety of agro products last decades, showing the wide-field and noncontact imaging, depth- and resolution-varying, as well as signal enhancement. SFDI can also be used to reconstruct the three-dimensional distribution of optical features related to tissue physicochemical properties in the field of nondestructive detection. This study first overviewed the origins and development of SFDI in the field of agricultural engineering, and then introduced the main working principles of SFDI, including system components, light propagation model, data measurement and processing, and inverse algorithms for optical property estimation. Specifically, the SFDI was first applied to the nondestructive detection of bruising on Golden Delicious apples in 2007, indicating a better performance to distinguish the bruised apple from the sound one. The SFDI system is mainly composed of a light source, a digital projector, a CCD camera, a wavelength selective device, and a sample stage, the former three of which are the core components to directly determine the quality of structured illumination and collected images, as well as the testing efficiency. Calibration is also required for the SFDI system with the standard samples before evaluation. The specific procedure is followed. The images of target samples are first captured by the SFDI system. The light uniformity correction, image demodulation, system response calibration, and surface profile correction are then conducted to obtain the diffuse reflectance images for the quality and safety evaluation directly, or for the optical property estimation coupled with inverse algorithms. After that, the application status of SFDI was summarized in the field of agricultural engineering, including the measurement of optical property and quality/safety assessment of several thin-skinned fruits, such as apple, pear, kiwifruit, cucumber, and peach. The challenges and future perspectives of the SFDI technique were also presented eventually. Nevertheless, the current SFDI technique is derived mostly from the diffusion approximation, thereby hindering the application easy to introduce large measurement errors. There are great challenges when measuring the optical property of two- and multi-layered agro products. It is also lacking a standardized optical system for accurate estimation of the optical property. The SFDI presents better performance in the depth-varying detection, but the penetration depth is a bit shallow limited to the millimeter level. Moreover, the demand for portable handheld devices of the SFDI technique is ever increasing in recent years. This review can provide a critical overview of the development of the SFDI technique for better understanding in the field of agricultural engineering. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to explore the suitable technology for the reclamation of erosion gullies in the black soil area of the Northeast China. In this paper, Xinhua farm is selected as the research area which is located in Hegang City, Heilongjiang Province, China. Aiming at the cause of erosion gullies, a new technology of filling and reclamation erosion gully with coal gangue was introduced and the post effect of the new technology was studied, including, the technological process of filling and reclamation, the influence of the thickness change of reclamation filling materials on the drainage characteristics of the gully, the fertility status and heavy metals pollution degree in the reclaimed soil. This paper aimed to explore the feasibility and breakthrough points of the technology of filling erosion gullies with coal gangue. The results showed that: 1) The increase in soil layer thickness could weaken the drainage capacity of the gully, while the increase of mixed size coal gangue thickness and large size coal gangue could increase the drainage capacity of the gully in different degrees. The interaction between the soil layer thickness and large size coal gangue layer thickness obviously influenced the drainage capacity of the gully. When the thickness of soil layer, mixed size coal gangue layer and large size coal gangue layer were 53.42, 38.51, 90 cm respectively, the shortest outflow time was 145.129 s, the drainage capacity of simulated 2 m deep gully was the strongest in this mode. 2) After 4 years of gully reclamation, the soil bulk increased, the soil acidity improved, the content of total potassium was the same as CK, but the total nitrogen, total phosphorus and organic matter content were lower than CK. And then the comprehensive fertility of soil was less than CK, which is 66.71%-80.81% of CK, and the average level only reach to 72.75%. But it was slightly higher than that of the second accumulated temperature zone in Heilongjiang Province. 3) The content of Pb was basically the same as CK and background value of local control soil; however, as for Cr and Cu, they were higher than CK and background value of local control soil in the reclaimed soil of monitoring gully. But the content of Cr, Pb, Cu are not higher than the second level standard value of national environmental quality of China. . There are slight pollution and slight enrichment of heavy metals Cr, Pb and Cu in monitored gully reclamation soil, so coal gangue can be used as a material for filling erosion gully for reclamation. However, in the long term, attention should be paid to the problem of soil heavy metal enrichment during reclamation. [ABSTRACT FROM AUTHOR]

Methanol and biodiesel are the oxygenated alternative fuels of diesel engine, which can effectively reduce particulate emissions of diesel engines. However, due to the low cetane number of methanol, it is difficult for methanol to ignite in diesel engine. The addition of cetane number improver is an effective method to improve the ignition performance of diesel engine fuels. In order to study the effects of different cetane number improvers on diesel engine emission pollutants, three kinds of cetane number improvers, such as alkyl nitrates, naphthyl nitrates and ethers were chosen and added to the methanol / biodiesel blend fuel with the mixing ratios of 0.3%, 0.3%, and 3%, respectively. The effects of the cetane number improvers on the physical and chemical properties of methanol/biodiesel blend were investigated. The engine bench test was carried out on the 186F diesel engine without adjusting the structure of the diesel engine during the test. The in-cylinder pressure and exhaust temperature of the diesel engine fueled with methanol/biodiesel blend was measured at 1 800, 3 000 r/min, 25%, and 100% load, then the ignition delay and combustion duration were calculated. The variation of pollutants such as HC, CO, NOX and smoke emitted from the diesel engine at 1 800 and 3 000 r/min, 10%, 25%, 50%, 75% and 100% loads were measured. The effects of cetane number improvers on diesel engine exhaust pollutants were investigated. The results showed that the addition of cetane number improvers had little effects on the density, viscosity and other physical and chemical properties of the methanol/biodiesel blend, but the cetane number of the blend was obviously increased. Because of the low decomposition activation energy of the cetane number improvers, the improvers can help the blend to shorten the chemical delay period. With the addition of cetane number improvers to the methanol/biodiesel blend, the in-cylinder pressure peak was increased, the ignition delay was shortened, and the combustion duration was prolonged. In addition, the corresponding crankshaft angle of in-cylinder pressure peak was advanced. When the amount of improvers was equal, the ignition delay period of alkyl nitrates mixture was the shortest among the three cetane number improvers. When the diesel engine changed from 25% load to 100% load, the exhaust temperature was increased by 194-235 K at the same speed. While the diesel engine speed had smaller effects on the exhaust temperature and the variation range was −3.24%-3.45%. With the addition of cetane number improvers, the HC and CO emission were increased, especially at higher engine load. However, the addition of cetane number improvers can reduce the NOX and the smoke. When the diesel engine was at 3 000 r/min, 100% load, NOX was reduced by 12.90%, 6.45%, 3.87% with the addition of alkyl nitrate, naphthenic nitrates and ethers respectively, and the smoke was reduced by 11.76%, 17.65%, 38.24%. The addition of cetane number improver in methanol/biodiesel blends not only can improve the ignition characteristics of the fuels, but also reduce NOx and particulate emissions. [ABSTRACT FROM AUTHOR]

In order to improve the catalytic activity, anti-carbon deposition and regeneration performance of dolomite catalyst which was easy to accumulate carbon and deactivate during biomass catalytic gasification, a fixed-bed suction gasifier test system was adopted in this study. Firstly, rod-shape particles were prepared from pine chips wastes using Fe-Dol-Ben (bentonite/limonite modified dolomite) as catalyst and fixed-bed downdraft gasifier as main body. An experimental system for biomass steam gasification was established. Then the high temperature steam catalytic gasification test was carried out with the above two raw materials. Finally, the effects of several factors on the catalytic gasification performance of pine wood and carbon deposition on the catalyst surface were studied. The factors affecting the catalytic gasification performance and carbon deposition on the catalyst surface were gasification temperature (temperature range is 700-1000 ℃), iron content (mass percentage range is 5%-20%) and the number of catalyst used (catalyst used number is 1-4). The results showed that the mass percentage of iron in FeDol-Ben catalyst was 15%, the gasification temperature was 900 ℃, and the volume fraction of hydrogen in gasification gas reaches the maximum of 58.38% under the condition that the mass ratio of steam to pine wood was 1. The results also showed that with the increasing of gasification temperature, the carbon deposition in FeDol-Ben catalyst decreased gradually, reaching the minimum value at 1 000 ℃, 80% lower than that at 700 ℃. In addition, the volume fraction of hydrogen in gasified gas increased first and then decreased with the increasing of iron content. At the same time, the carbon content decreased first and then increased, and the catalytic effect was better when the iron mass content was 15%. Under the same conditions as bentonite and pre-modified dolomite, the carbon deposition of Fe-Dol-Ben catalyst decreased by 80.6% and 53.6%, respectively. The experiment of catalyst regeneration and reuse showed that the crystal phase of the catalyst was basically the same as that of the pre-catalyst after the Fe-Dol-Ben catalyst regeneration at 700 ℃. The volume fraction of hydrogen in gasification gas decreased with the increasing of the number of times of regeneration, and the carbon deposition of the catalyst increased gradually. The results also showed that the volume fraction of hydrogen was still close to 50% after four times of catalytic gasification, which maintained the catalytic effect. In summary, considering the gasification effect, carbon deposition and economic factors, the optimization conditions were iron content of 15% and gasification temperature of 900 ℃. The study can provide reference for the development of bentonite/limonite modified dolomite catalyst and biomass high temperature steam catalytic gasification technology. [ABSTRACT FROM AUTHOR]

Abstract: Methanol and biodiesel are the oxygenated alternative fuels of diesel engine, which can effectively reduce particulate emissions of diesel engines. However, due to the low cetane number of methanol, it is difficult for methanol to ignite in diesel engine. The addition of cetane number improver is an effective method to improve the ignition performance of diesel engine fuels. In order to study the effects of different cetane number improvers on diesel engine emission pollutants, three kinds of cetane number improvers, such as alkyl nitrates, naphthyl nitrates and ethers were chosen and added to the methanol / biodiesel blend fuel with the mixing ratios of 0.3%, 0.3%, and 3%, respectively. The effects of the cetane number improvers on the physical and chemical properties of methanol/biodiesel blend were investigated. The engine bench test was carried out on the 186F diesel engine without adjusting the structure of the diesel engine during the test. The in-cylinder pressure and exhaust temperature of the diesel engine fueled with methanol/biodiesel blend was measured at 1 800, 3 000 r/min, 25%, and 100% load, then the ignition delay and combustion duration were calculated. The variation of pollutants such as HC, CO, NOX and smoke emitted from the diesel engine at 1 800 and 3 000 r/min, 10%, 25%, 50%, 75% and 100% loads were measured. The effects of cetane number improvers on diesel engine exhaust pollutants were investigated. The results showed that the addition of cetane number improvers had little effects on the density, viscosity and other physical and chemical properties of the methanol/biodiesel blend, but the cetane number of the blend was obviously increased. Because of the low decomposition activation energy of the cetane number improvers, the improvers can help the blend to shorten the chemical delay period. With the addition of cetane number improvers to the methanol/biodiesel blend, the in-cylinder pressure peak was increased, the ignition delay was shortened, and the combustion duration was prolonged. In addition, the corresponding crankshaft angle of in-cylinder pressure peak was advanced. When the amount of improvers was equal, the ignition delay period of alkyl nitrates mixture was the shortest among the three cetane number improvers. When the diesel engine changed from 25% load to 100% load, the exhaust temperature was increased by 194-235 K at the same speed. While the diesel engine speed had smaller effects on the exhaust temperature and the variation range was −3.24%-3.45%. With the addition of cetane number improvers, the HC and CO emission were increased, especially at higher engine load. However, the addition of cetane number improvers can reduce the NOX and the smoke. When the diesel engine was at 3 000 r/min, 100% load, NOX was reduced by 12.90%, 6.45%, 3.87% with the addition of alkyl nitrate, naphthenic nitrates and ethers respectively, and the smoke was reduced by 11.76%, 17.65%, 38.24%. The addition of cetane number improver in methanol/biodiesel blends not only can improve the ignition characteristics of the fuels, but also reduce NOx and particulate emissions. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The experimental Chlorella of Chlorella pyrenoidosa FACHB-5 and Chlorella vulgaris FACHB-8 was cultured in a 1 000 mL Erlenmeyer flask with 700 mL nutrient solution in an artificial climate incubator. The culture temperature, illuminance, airflow rate and continuous illumination time were (26±1)°C, 4 000 lx, 1.5 L/min and 24 h, respectively. The biogas slurry of chicken manure achieved after anaerobic digestion at medium temperature (35°C) and high temperature (55 °C) for 45 d was used as nutrient source for Chlorella culture. The main compositions and characteristics of biogas slurry digested at 35 and 55°C were 2 417.63 and 2 554.37 mg/L for total nitrogen, 2 218.27 and 2 376.24 mg/L for ammonium nitrogen, 16.91 and 13.44 mg/L for total phosphorus, 10 021.82 and 10 104.13 mg/L for chemical oxygen demand (COD), 8.25 and 8.18 for pH value, 698 and 653 NTU for turbidity, and 2.68 and 2.52 mPa·s for viscosity, respectively. The semi-continuous culture of Chlorella was realized by discharging nutrient solution of 10% and adding new nutrient solution of 10% at the same time daily. Furthermore, the addition ratios of unsterilized biogas slurry in daily new nutrient solution were 10%, 20% and 30%, respectively. Effects of 3 different addition ratios of unsterilized biogas slurry digested at 35 and 55°C on the semi-continuous culture of Chlorella were studied systematically based on the analysis of nutrient solution during Chlorella culture including OD680, total nitrogen, ammonium nitrogen, total phosphorus, and so on. The results showed that the Chlorella pyrenoidosa FACHB-5 and Chlorella vulgaris FACHB-8 could adapt the culture environment well and grow rapidly when the addition ratios of unsterilized biogas slurry in daily new nutrient solution were 10% and 20%. Furthermore, the OD680 values of 2 types of Chlorella were maintained at 2.40-2.69 at the end of Chlorella culture for 10 d. However, the growth of FACHB-5 and FACHB-8 in the later period of culture experiment was restrained significantly when the addition ratio of unsterilized biogas slurry in daily new nutrient solution was 30%. Furthermore, the growth rates and adaptive capacity of FACHB-5 in the nutrient solution containing more biogas slurry were better than that of FACHB-8. A similar fluctuation trend was achieved in OD680 of different comparative samples with biogas slurry addition. However, the OD680 values of comparative samples with 55 digestive biogas slurry were over 0.13 higher than that of comparative sam°C ples with 35°C digestive biogas slurry, especially for the comparative samples with biogas slurry of 10% and 20% addition ratios. Moreover, the OD680 values of FACHB-5 and FACHB-8 were maintained at 1.98-2.15 and 1.79-1.92 at the end of Chlorella culture for 10 d, respectively. Therefore, the effects of biogas slurry digested at 55°C on semi-continuous culture of Chlorella were superior than that of biogas slurry digested at 35°C. The results supply references for the theoretical research and subsequent large-scale application of Chlorella culture using biogas slurry digested at different temperatures. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Diesel exhaust particle matter is the main source of air pollutants PM2.5. It is limited not only on the quality but also on the number. Therefore, the widespread use of clean alternative fuel in diesel engine is one of the effective ways to reduce particulate emission. Previous study reported the effects of methanol/biodiesel blending fuel on the volatilization, oxidation process parameters and kinetic parameters of particle matter emitted from diesel engine. The volatilization, oxidation process parameters of particle matter varied with the methanol/biodiesel blending ratio (100%, 5%, 10%, 15%) were measured by the TGA/DSCI thermal analyzer, manufactured by Mettler, Switzrland. The mass change curves of the particles in the surroundings of N2 and O2 were obtained by thermo-gravimetric analyzer. Further, the volatilization and oxidation features of the particles were studied according to the pyrolysis curves (TG/DTG), the characteristic temperature and activation energy of pyrolysis of particles were calculated by tangent method and Flynn-Wall-Ozawa (FWO) pyrolysis kinetics. The results showed that when the content of H2O in particle matter was increased from 2.6% to 3.5%, the quality of soluble organic fraction (SOF) in particle matter could be increased from 26.1% to 32.5%, the peak of mass change rate and the temperature of the peak of SOF would be increased with the increasing of the methanol ratio. In O2 surroundings, the derivative thermal gravimetry curves of particle matter under 4 kind of blending fuels showed that the change way of SOF was consistent with that in N2 surroundings, but the peak value in O2 atmosphere was obviously greater. The soot mass showed a decreasing trend with the increase of ratio of methanol, which was decreased from 70.3% to 63.8%. In addition, the peak of mass change rate of soot was increased and the temperature of the peak was decreased, which indicated that the particles were more easily oxidized. The initial combustion temperature of soot was decreased from 488 °C to 458 °C. Meanwhile, the SOF initial combustion temperature and the burnout temperature were slightly lower, and the total time of pyrolysis reaction of particles was shortened. The activation energy of particle matter was reduced from 140.3 kJ/mol to 117.3 kJ/mol. In summary, the pyrolysis properties of the particles were enhanced and the thermo chemical reaction of particles was easily carried out. These results could provide a theoretical basis for the treatment of methanol/biodiesel combustion particulates, and it is helpful to the design and application of diesel particulate filter (DPF). [ABSTRACT FROM AUTHOR]

This study mainly focused on the following problems like the higher cost of adding nitrogen and phosphorus in chlorella culture; the delayed and ineffective use of biogas slurry containing rich nutrient elements just as nitrogen, phosphorus, and so on after anaerobic fermentation; the easily contaminated microalgae caused by undesired microbes in microalgae culture; the higher cost of microalgae culture due to the biogas slurry pretreatments like sterilization and so forth when biogas slurry was serving as the culture medium; etc. The culture medium was the mixture of BG11 medium and biogas slurry from straw by anaerobic fermentation for 30 days. The biogas slurry fermented from straw was non-sterilized and relatively simple in composition. The algae species FACHB-5 and FACHB-8 chlorella were used. An artificial climate incubator was also used, in which the temperature for microalgae culture was kept at (26±1)℃, the light intensity was 4 000 lx, the light time was 24 hours continuously, and the ventilation volume was 1.5 L/min. In the experiment, the total nitrogen at the beginning was 180, 215 and 297 mg/L respectively in the experimental medium groups. The addition content of biogas slurry was 20%, 30% and 40% separately; and the results showed that the total nitrogen content of culture liquid was reduced to 6, 8 and 12 mg/L with the different biogas slurry treatments (20%, 30% and 40%), respectively, and the removal rate of total nitrogen was more than 96%. The total phosphorus content at the beginning was 14, 19 and 24 mg/L respectively in the experimental medium groups with the addition of biogas slurry was 20%, 30% and 40%, separately; At the end of the experiment, they reduced to less than 2 mg/L, and the removal rate of total phosphorus was more than 92%. Chemical oxygen demand (COD) content at the beginning was 4 500, 6 993 and 9 366 mg/L respectively, in the experimental medium groups with the addition of biogas slurry was 20%, 30% and 40%, and at the end of the experiment they reduced to 160, 400 and 540 mg/L respectively, the removal rate of COD was more than 90%. The experimental results showed that both FACHB-5 and FACHB-8 algae species could well adapt to biogas slurry which was relatively high in COD content from straw by anaerobic fermentation, and could well make the use of and remove the organic pollutants from biogas slurry. Compared with FACHB-5 algae species, FACHB-8 algae species needed shorter time to adapt, and had stronger adaptability to biogas slurry. What's more, there was a strong correlation between the degradation of organic pollutants and the growth of chlorella in every experimental medium group. The study may lay a theoretical foundation for the application of biogas slurry which will be directly used in microalgae culture, and may have the magnificent significance for large-scale microalgae culture. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to reveal the dynamic essence of combustion cyclic fluctuations, gasoline, liquefied petroleum gas (LPG) and compressed natural gas (CNG) were burned in the ignition engine, and the cyclical fluctuations of combustion pressure were investigated using nonlinear dynamics method. The pressure data in 200 cycles were collected to discuss the regulation of in-cylinder pressure which varied with the time and to analyze cyclical fluctuation factors of the maximum break pressure. In addition, time sequences of pressure in cylinder were rebuilt three-dimensionally combined with differential coordinates, and the principles and distribution features of phase space structure changing during combustion period were studied. Phase space tracks were simplified and rebuilt by the Poincare section method to probe into the Poincare mapping points distribution of in-cylinder pressure in cross sections on whose the second derivative was zero (The second derivative of pressure was zero, Z=0) and the pressure rise rate was zero (The first derivative of pressure was zero, Y=0). The cyclical fluctuations of indicative mean effective pressures (IMEPs) were analyzed while burning 3 fuels separately. Results indicated that the cyclic fluctuation coefficient of in-cylinder pressure was 7.5% while the spark ignition engine burnt gasoline, and the coefficient increased to 7.8% and 13.8% respectively while burning LPG and CNG. The phase space track of in-cylinder pressure was a closed curve with chaos properties showing the intake and exhausting process in sharp curve and the combustion process in arc curve when the initial period structure of combustion was relatively compact and the diffusion was most obvious in the maximum of Y direction, and then it duplicated quickly after reaching the maximum at X axis direction(X axis represents pressure. Compact track distributions were observed while burning gasoline, however, there were partial combustion and lost fire cycles when LPG and CNG were employed in which the reconstructed phase space trajectory spread gradually, the degree of divergence maximized at the X axis maximum and the combustion stability declined. Poincare mapping decrease the complexity of the phase space structure effectively. Specifically, Poincare mapping points on Z=0 and Y=0 plane were distributed in the shape of ribbon. On the plane of Z=0, the slope of scatter distribution was 0.076 and the correlation between combustion parameters was strong. It showed that scatters were close together when gasoline was used, however, and mapping points diffused gradually with combustion parameters improved casually. Besides, cyclical fluctuation coefficient of the mean indicated pressure was 2.16%, cyclical fluctuations of IMEPs were slighter and the IMEPs before and after were dramatically relevant to each other, the working process was also stable when gasoline was used. On the other hand, cyclical fluctuations were increased gradually, when the slope was 0.089 and 0.085, the activation energy of the fuel was improved, the combustion speed was declined, the combustion cyclic fluctuations gradually increased to 11.1% and 15.1% respectively, the combustion stability decreased and the randomness of combustion enhanced and a certain chaotic characteristic was shown when LPG and CNG were burned. In summary, the combustion process of engine has chaotic characteristic, and the stability of combustion is declined when the engine is fueled with LPG and CNG. [ABSTRACT FROM AUTHOR]

Diesel particulate is one of the main sources of atmospheric particulate matter PM2.5, which seriously harms human health. With the emission regulations become increasingly stringent, higher requirements have been put forward, not only on the quality of particulate emissions but also on the particle number. The change trend of particle size distribution and oxidation characteristics of the diesel particulate are analyzed, in order to understand the change process of the diesel engine particles in the exhaust pipe. For further reduction of the diesel engine exhaust particulate, the post processing technologies have been widely used, such as diesel particulate filter(DPF). A lot of carbon dioxide(CO2), water vapor, hydrocarbon(HC) and particulate matter and other components are contained in the diesel engine exhaust, and the temperature, pressure and other parameters of the exhaust gas flow changed in the exhaust pipe of the diesel engine. The exhaust particulate matter was also accompanied by condensation and oxidation reduction and other physical and chemical processes, and as a result the physical and chemical characteristics of particles also changed. The particle size distribution and oxidation characteristics of the particles were important for the particle capture efficiency and regeneration. The particle size distribution along the direction of movement of the exhaust gas flow and different positions was measured by using the engine exhaust particle size spectrometer(EEPS). Along the direction of the exhaust gas particles at different sites during the pyrolysis process, pyrolysis kinetic parameters, ignition temperature and burnout characteristics index were studied, and particle pyrolysis reaction rate and degree of difficulty were analyzed by using the device of thermogravimetry/differential simultaneous thermal analyzer. According to the experiment data, along the direction of the exhaust gas flow, the number of nucleation particles decreased, the number of aggregated particles increased, and the particle size of aggregated particles became larger. It showed that in SOF(soluble organic fraction) evaporation stage and soot oxidation process, the particle weight loss rate increased, and the weight loss peak temperature decreased; along with the diesel engine exhaust gas flow direction, when reducing the temperature of the gas, the content of H2O in particles increased from 1.3% to 2.46%, the content of SOF increased from 38.21% to 42.05%, the soot percent content decreased from 57.84% to 52.24%, and the ash content increased from 3.01% to 3.25%; the pre-exponential factor of particle was reduced from 7.93×1012 to 4.67×1012 and the activation energy could be reduced from 157.3 to 127.9, the ignition temperature decreased from 546 to 501 ℃, which was reduced by about 8.2%, the combustion characteristic index increased from 8.16×10-9 to 1.62×10-8, and the burnout characteristics index was risen by 14.5%. Therefore, based on the study of the particle size distribution and oxidation characteristics which came from the small non-road diesel engine exhaust pipe of particles, it can be concluded that along the exhaust gas flow direction, with lower exhaust temperature, the burnout performance of the particle gets improved and effectively raises the regeneration of particle collector. [ABSTRACT FROM AUTHOR]

Pollutant emissions of diesel engine are mainly particulate matters, nitrogen oxide (NOx), hydrocarbon (HC), carbon moNOxide (CO), etc. The NOx, sulfide and particulate matters can form aerosol in the atmosphere, which is one of main causes leading to fog and haze. The concentration of small and medium scale particles such as PM2.5 and NOx is increasing with the wide application of diesel engine. The fog and haze weather occurs frequently, which has negative impacts on human health. It is quite necessary to carry out research on reducing particulate matters emitted from diesel engine. The diesel particulate matters and NOx emissions can be effectively controlled by adding the oxygen-containing fuel in the reaction process combined with the technology of the exhaust gas recirculation (EGR), which yet has multiple effects on the microstructure and oxidation behavior of the diesel engine particulate matters. In order to analyze and comprehend the effect of particle structure and fractal characteristics, a particulate matter sampling device was employed to collect the diesel engine particulate matters, which took oxygenated fuels combined with the technology of EGR into consideration. And the effects of different EGR rate (0%, 10% and 20%) on the particulate matters, which were produced in the combustion of N-butanol/diesel blended fuel with 10% N-butanol (N10), were studied with the thermal field emission scanning electron microscope (SEM) and high resolution electron microscopy (TEM), and the results were analyzed by the image technology. To be specific, the changing rule of physical structure parameter including the particulate matter microstructure, the average particle size of particulate matter group and the fractal dimension were analyzed, as well as the fringe separation distance and the fringe length distribution of basic carbon particles. It could be well observed that there was obvious clusters structure of particulate matters formed by combustion under 3 different conditions: N10EGR0, N10EGR10% and N10EGR20%. What was more, the range of particulate matter size was mainly concentrated between 30 and 70 nm which showed the normal single peak distribution. And the size of particulate matters demonstrated the pattern moving to larger figures gradually with the EGR rate increasing. Also the average size of particulate matter of N10EGR20% increased by 19% compared to N10EGR0. The gradual decreasing of box dimension indicated the fact that the intergranular degree of clusters gradually weakened. On the other hand, the basic carbon particles under different EGR conditions presented the similar structures, which looked like spherical carbon layer fingerprints. The basic carbon particulate matters were composed of 2 parts, the basic kernel layer and the shell. The basic kernel layer was the amorphous carbon structure, and the shell was the structure of graphite crystallite. Moreover, with the increasing of the EGR rate, the basic kernel layer was arranged more disorderly and the shell carbon particulate matters presented more irregular graphite crystal structure. To summarize, the average fringe separation distance of basic carbon particles was increased gradually as well as the average tortuosity distribution, and the average fringe length distribution was decreased with the increasing of EGR rate. The oxidation activity of particulate matters was improved with the adoption of EGR. This study can provide a theoretical reference for the formation mechanism of particulate matters and the measures to reduce the particulate matter emission of diesel engine by oxygenated fuel and the technology of EGR together. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Particulate matter emitted from diesel engine is a factor that makes PM2.5 (particulate matter with a diameter of lower than 2.5 μm) increase, which is related to several adverse health effects including respiratory tract inflammation and cancer. Particulate matter is classified to 3 size modes, i.e. the nucleation mode (<50 nm), the accumulation mode (100-1 000 nm) and the coarse mode (>1 000 nm). As is known to all, particulate matter with smaller size does more harm to human than particulate matter with larger size. It is very necessary to carry out research on reducing particulate matter emitted from diesel engine, especially particulate matter with smaller size. It has been demonstrated that there is graphene structure in particulate matter emitted from diesel engine and graphene structure is related to particulate matter removal. Micro-orifice uniform deposition impactor which was produced in MSP company in America was used to collect diesel particulate matter with 3 size ranges, which were 0.18-0.32 μm, >0.32-0.56 μm and >0.56-1 μm respectively. Raman spectroscopy, a fast and nondestructive method, was used to test crystal structure of carbon material. Near edge X-ray absorption spectra, a nondestructive method, was adopted to characterize molecular structure and valence state of carbon atom by using synchrotron radiation technique. DXR Raman spectrometer and soft X-ray microscopy beamline station were used to analyze the defect type of graphene structure, degree of graphitization, crystallite size of graphene, neighboring graphene spacing, molecular structure and valence state of carbon atom. The results showed that the ratio of D1 peak to D2 peak ranged from 3.34 to 4.01, which indicated that the defect type of graphene structure in diesel particulate matter mainly was graphene edge defect. With the size of particulate matter decreasing, the proportion of graphene edge defect increased. When the size of particulate matter increased, width at half maximum of D1 peak increased by 2.8 and 6.7 cm-1, indicating that the material type in particulate matter increased and the chemical heterogeneity of particulate matter was higher. The ratio of D1 peak to G peak decreased by 14.67% and 27.17% respectively with particulate matter changing from small size to the other 2 bigger sizes, which indicated that the proportion of order graphene in diesel particulate matter increased and led to higher graphitic-like structure and degree of graphitization. When the size of particulate matter increased, the relative intensity of D3 peak decreased by 13.73% and 39.22%, respectively. That was to say the proportion of amorphous carbon especially organic ingredients reduced. The length of C-C bond in graphene lattice had no relationship with the size of diesel particulate matter. The length of C-C bond in graphene lattice of diesel particulate matter with 3 size ranges was about 0.142 nm. When the size of particulate matter increased, the crystallite size of graphene increased and the neighboring graphene spacing decreased, which indicated the oxidative reactivity of particulate matter reduced and the energy in the process of oxidizing diesel particulate matter increased. The types of surface functional groups in particulate matter had no relationship with the size of diesel particulate matter. There were many types of surface functional groups which were “graphene” C=C, C=C, aliphatic C=C, phenolic C-OH, ketones C=O, aliphatic C-H and carboxy C=O respectively. With the size of particulate matter increasing, aliphatic C=C, aliphatic C-H, carboxy C=O in diesel particulate matter decreased and “graphite” C=C, phenolic C-OH, ketones C=O in diesel particulate matter increased. This study can provide reference for the perfection of the formation mechanism of diesel particulate matter with different size range and for the optimization of particulate matter removal device. [ABSTRACT FROM AUTHOR]