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Chris Hayman - One of the best experts on this subject based on the ideXlab platform.
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Thermal Conversion of elephant grass pennisetum purpureum schum to bio gas bio oil and charcoal
Bioresource Technology, 2008Co-Authors: Vladimir Strezov, Tim Evans, Chris HaymanAbstract:Abstract Elephant grass is an abundant, fast growing plant with significant potential as a renewable energy source and for Conversion to higher calorific value fuels. This work investigates Thermal Conversion of elephant grass to bio-gas, bio-oil and charcoal under two heating rates of 10 and 50 °C/min. The energy required to pyrolyse elephant grass was evaluated using computer aided Thermal analysis technique, while composition of the resultant bio-gas and bio-oil products were monitored with gas chromatographic and mass spectroscopic techniques. At 500 °C, the bio-gas compounds consisted primarily of CO 2 and CO with small amounts of methane and higher hydrocarbon compounds. The heat of combustion of the bio-gas compounds was estimated to be 3.7–7.4 times higher than the heat required to pyrolyse elephant grass under both heating rates, which confirms that the pyrolysis process can be self-maintained. Faster heating rate was found to increase the amount of liquid products by 10%, while charcoal yields remained almost the same at 30%. The bio-oil mainly consisted of organic acids, phthalate esters, benzene compounds and amides. The amount of organic acids and benzene compounds were significantly reduced at 50 °C/min, while the yields of phthalate esters and naphthalene compounds increased. The difference in bio-oil composition with increased heating rate is believed to be associated with the reduction of the secondary reactions of pyrolysis, which are more pronounced under lower heating rate.
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Thermal Conversion of elephant grass pennisetum purpureum schum to bio gas bio oil and charcoal
Bioresource Technology, 2008Co-Authors: Vladimir Strezov, Tim Evans, Chris HaymanAbstract:Elephant grass is an abundant, fast growing plant with significant potential as a renewable energy source and for Conversion to higher calorific value fuels. This work investigates Thermal Conversion of elephant grass to bio-gas, bio-oil and charcoal under two heating rates of 10 and 50 degrees C/min. The energy required to pyrolyse elephant grass was evaluated using computer aided Thermal analysis technique, while composition of the resultant bio-gas and bio-oil products were monitored with gas chromatographic and mass spectroscopic techniques. At 500 degrees C, the bio-gas compounds consisted primarily of CO2 and CO with small amounts of methane and higher hydrocarbon compounds. The heat of combustion of the bio-gas compounds was estimated to be 3.7-7.4 times higher than the heat required to pyrolyse elephant grass under both heating rates, which confirms that the pyrolysis process can be self-maintained. Faster heating rate was found to increase the amount of liquid products by 10%, while charcoal yields remained almost the same at 30%. The bio-oil mainly consisted of organic acids, phthalate esters, benzene compounds and amides. The amount of organic acids and benzene compounds were significantly reduced at 50 degrees C/min, while the yields of phthalate esters and naphthalene compounds increased. The difference in bio-oil composition with increased heating rate is believed to be associated with the reduction of the secondary reactions of pyrolysis, which are more pronounced under lower heating rate.
Qian Wang - One of the best experts on this subject based on the ideXlab platform.
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photo Thermal Conversion properties of hybrid cuo mwcnt h2o nanofluids for direct solar Thermal energy harvest
Applied Thermal Engineering, 2019Co-Authors: Ruomei Zhang, Zhihao Wang, Qian WangAbstract:Abstract Water-based hybrid nanofluids with CuO and multi-walled carbon nanotube (MWCNT) were prepared and well dispersed. The optical absorption properties and photo-Thermal Conversion performance of hybrid CuO-MWCNT/H2O nanofluids at different concentration mixing ratios (CMRs) were experimentally tested and compared to evaluate the solar Thermal energy harvest capability. The mixture of CuO-MWCNT nanofluids significantly enhanced solar energy spectral absorption as compared with individual CuO or MWCNT nanofluids, and the extinction coefficients of hybrid nanofluids were mostly equal to the sum of individual components. At appropriate CuO/MWCNT CMRs, the solar weighted absorption fractions of hybrid nanofluids are almost 100% at an optical penetration distance of 1 cm. Besides, the photo-Thermal Conversion performance of hybrid nanofluids was largely superior to individual nanofluids but highly dependent on the CMR, and an excessive addition of individual component could lower the performance. At a CuO/MWCNT CMR of 0.15 wt%/0.005 wt%, a maximum terminal temperature rise of 14.1 °C was achieved with respect to DI water after a light irradiation time duration of 45 min. The coexistence and interaction of CuO nanoparticles and MWCNT fibers in the aqueous suspension at evaluated temperatures were took into account to explain the optical absorption behavior and then the photo-Thermal Conversion properties. This study suggests that hybrid CuO-MWCNT/H2O nanofluids at appropriate CMRs provide a potential alternative in direct solar Thermal energy harvest.
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photo Thermal Conversion characteristics of mwcnt h2o nanofluids for direct solar Thermal energy absorption applications
Applied Thermal Engineering, 2017Co-Authors: Min Tian, Ruomei Zhang, Xinyue Han, Qian WangAbstract:Abstract Stable water-based multi-walled carbon nanotube (MWCNT) nanofluids with mass fractions ranging from 0.0015% to 0.1% were prepared. To investigate the photo-absorption properties and photo-Thermal Conversion performance of MWCNT-H2O nanofluids, heating and light-irradiation cycling tests were experimentally performed at temperatures below 90 °C. Heat treatment is beneficial to improve the optical absorption capability of MWCNT-H2O nanofluids, and there existed an optimal concentration of about 0.01 wt% with respect to the spectral transmittance and extinction coefficient. Extinction coefficients of MWCNT-H2O nanofluids increased linearly with the MWCNT concentration in a range of 0–0.01 wt% at wavelengths of 500–900 nm. Compared to DI water, the temperature of MWCNT-H2O nanofluid at the optimal mass fraction of 0.01% was increased by about 14.8 °C (or 22.7%) after a light irradiation time of 45 min. The photo-Thermal Conversion performance was enhanced with increasing the light irradiation cycle at appropriate concentrations of nanofluid, and the probable mechanism caused by the CNT-fiber agglomeration was qualitatively analyzed. The receiver efficiency decreased with increasing the light irradiation time, and the highest value was up to 96.4% at 0.01% mass fraction. The prospects for possible applications of MWCNT-H2O nanofluids in low-temperature direct solar Thermal energy absorption were presented.
Vladimir Strezov - One of the best experts on this subject based on the ideXlab platform.
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Thermal Conversion of elephant grass pennisetum purpureum schum to bio gas bio oil and charcoal
Bioresource Technology, 2008Co-Authors: Vladimir Strezov, Tim Evans, Chris HaymanAbstract:Abstract Elephant grass is an abundant, fast growing plant with significant potential as a renewable energy source and for Conversion to higher calorific value fuels. This work investigates Thermal Conversion of elephant grass to bio-gas, bio-oil and charcoal under two heating rates of 10 and 50 °C/min. The energy required to pyrolyse elephant grass was evaluated using computer aided Thermal analysis technique, while composition of the resultant bio-gas and bio-oil products were monitored with gas chromatographic and mass spectroscopic techniques. At 500 °C, the bio-gas compounds consisted primarily of CO 2 and CO with small amounts of methane and higher hydrocarbon compounds. The heat of combustion of the bio-gas compounds was estimated to be 3.7–7.4 times higher than the heat required to pyrolyse elephant grass under both heating rates, which confirms that the pyrolysis process can be self-maintained. Faster heating rate was found to increase the amount of liquid products by 10%, while charcoal yields remained almost the same at 30%. The bio-oil mainly consisted of organic acids, phthalate esters, benzene compounds and amides. The amount of organic acids and benzene compounds were significantly reduced at 50 °C/min, while the yields of phthalate esters and naphthalene compounds increased. The difference in bio-oil composition with increased heating rate is believed to be associated with the reduction of the secondary reactions of pyrolysis, which are more pronounced under lower heating rate.
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Thermal Conversion of elephant grass pennisetum purpureum schum to bio gas bio oil and charcoal
Bioresource Technology, 2008Co-Authors: Vladimir Strezov, Tim Evans, Chris HaymanAbstract:Elephant grass is an abundant, fast growing plant with significant potential as a renewable energy source and for Conversion to higher calorific value fuels. This work investigates Thermal Conversion of elephant grass to bio-gas, bio-oil and charcoal under two heating rates of 10 and 50 degrees C/min. The energy required to pyrolyse elephant grass was evaluated using computer aided Thermal analysis technique, while composition of the resultant bio-gas and bio-oil products were monitored with gas chromatographic and mass spectroscopic techniques. At 500 degrees C, the bio-gas compounds consisted primarily of CO2 and CO with small amounts of methane and higher hydrocarbon compounds. The heat of combustion of the bio-gas compounds was estimated to be 3.7-7.4 times higher than the heat required to pyrolyse elephant grass under both heating rates, which confirms that the pyrolysis process can be self-maintained. Faster heating rate was found to increase the amount of liquid products by 10%, while charcoal yields remained almost the same at 30%. The bio-oil mainly consisted of organic acids, phthalate esters, benzene compounds and amides. The amount of organic acids and benzene compounds were significantly reduced at 50 degrees C/min, while the yields of phthalate esters and naphthalene compounds increased. The difference in bio-oil composition with increased heating rate is believed to be associated with the reduction of the secondary reactions of pyrolysis, which are more pronounced under lower heating rate.
Zhengguo Zhang - One of the best experts on this subject based on the ideXlab platform.
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improving the heat storage release rate and photo Thermal Conversion performance of an organic pcm expanded graphite composite block
Solar Energy Materials and Solar Cells, 2019Co-Authors: Min Xie, Xiaoming Fang, Jiangchang Huang, Ziye Ling, Zhengguo ZhangAbstract:Abstract A phase change material (PCM) with both high Thermal storage/release rate and good photo-Thermal Conversion performance not only is a good working medium for Thermal energy storage system but also show potential use in solar Thermal utilization. Herein, a strategy of further improving Thermal characteristics of an organic PCM/expanded graphite (EG) composite was explored. In this work, PA is selected as PCM. Specifically, the PA/EG composite was pressed into round blocks with different EG packing densities, and it is shown that the block that has the EG packing density of 320 Kg/m3 exhibits both large enthalpy and high Thermal conductivity. Then, two carbon materials, carbon fiber (CF) and graphite sheet (GS), were introduced into the optimal EG-based binary block to prepare two series of ternary blocks with different mass ratios of CF (GS) to EG, respectively. It is found that the ternary blocks containing GS always exhibit larger enthalpy and higher Thermal conductivity than the ones containing CF at every identical mass ratio. The suitable mass ratio of GS to EG has been selected as 0.5, at which the obtained ternary block possesses a Thermal conductivity of 16.5 W/mK, showing an increase by ca. 24%, while its enthalpy just decreases very slightly, as compared with the binary one. Moreover, it is revealed that the introduction of GS makes the ternary block exhibit accelerated heat storage and release rates and enhanced photo-Thermal Conversion performance. These good characteristics along with excellent Thermal reliability endow the PA/GS/EG block with potential applications.
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preparation and photo Thermal Conversion performance of modified graphene ionic liquid nanofluids with excellent dispersion stability
Solar Energy Materials and Solar Cells, 2017Co-Authors: Jian Liu, Leilei Chen, Xiaoming Fang, Zhengguo ZhangAbstract:Abstract Dispersion stability has been long considered as a critical issue for applying nanofluids in various fields, especially for the applications at elevated temperatures. Herein a novel route is explored to improve the dispersion stability of graphene (GE)/ionic liquid (IL) nanofluids for use as working fluids in medium- and high-temperature direct absorption solar collectors (DASCs), which involves modifying GE according to the molecular structure of the IL. Specifically, GE was modified using the reagents and process for synthesizing [HMIM]BF 4 , followed by dispersing the modified GE (MGE) into [HMIM]BF 4. It is verified that the molecular chains similar to [HMIM]BF 4 have been grafted on the nanosheets of GE, and the MGE/[HMIM]BF 4 nanofluids exhibit much better dispersion stability than the one containing the unmodified GE, even at elevated temperatures. Moreover, the temperature profiles of the nanofluids containing MGE and GE were obtained both from the experimental measurement and the theoretical prediction using a one-dimensional transient heat transfer model. It is shown that the experimental data are in good agreement with the numerical ones for the MGE nanofluids, while a large deviation between them is found for the one containing the unmodified GE. And the MGE nanofluid shows enhanced receiver efficiency as compared to the GE one due to its much improved dispersion stability. Further, the transient model was used to predict the performance of the MGE nanofluid based DASCs under high solar concentrations. And by integrating the MGE concentration and the receiver height into a parameter, namely optical thickness, the optimization of the MGE nanofluid based DASC was carried out varying solar concentration, MGE concentration, nanofluid height and exposure time. It is revealed that the photo-Thermal Conversion performance of nanofluids greatly depends on its dispersion stability at elevated temperatures, and the MGE/[HMIM]BF 4 nanofluids possess excellent dispersion stability and show great potentials for use as the working fluids in DASCs. This work sheds light on effective routes for improving dispersion stability of nanofluids as well as numerical investigations on nanofluid based DASCs.
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optical absorption property and photo Thermal Conversion performance of graphene oxide water nanofluids with excellent dispersion stability
Solar Energy, 2017Co-Authors: Leilei Chen, Chao Xu, Xiaoming Fang, Zhengguo ZhangAbstract:Abstract Graphene oxide (GO) dispersed nanofluids were first explored to be used as working fluids for direct absorption solar collectors. The stability, optical absorption property, Thermal-physical property and photo-Thermal Conversion performance of the GO/water nanofluids with different mass fractions of GO were symmetrically investigated. The sedimentation experiment and Zeta potential (ζ) analysis showed that the GO/water nanofluids not only possess excellent long-term stability but also keep stable at elevated temperatures. A remarkable enhancement in optical absorption property was observed for the GO/water nanofluids due to the dispersion of GO into water. The GO/water nanofluids exhibited an obvious improvement in Thermal conductivity as compared with water. The photo-Thermal Conversion performance of the GO/water nanofluids were higher than that of water, and the highest efficiency was achieved by the one containing 0.02% of GO, which was 97.45% at 30 °C and 48.92% at 80 °C. The GO/water nanofluids with excellent dispersion stability, good optical absorption property and photo-Thermal performance show great promise for use as the working fluids in low temperature direct absorption solar collectors.
Yanqin Huang - One of the best experts on this subject based on the ideXlab platform.
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release and transformation pathways of various k species during Thermal Conversion of agricultural straw part 1 devolatilization stage
Energy & Fuels, 2018Co-Authors: Yanqin Huang, Huacai Liu, Hongyou Yuan, Xiuzheng Zhuang, Song Yuan, Xiuli YinAbstract:The serious K-induced ash problems during biomass Thermal Conversion are closely related to release and transformation behaviors of K. The aim of this work is to explore the contribution of differe...
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release and transformation pathways of various k species during Thermal Conversion of agricultural straw part 1 devolatilization stage
Energy & Fuels, 2018Co-Authors: Yanqin Huang, Hongyou Yuan, Xiuzheng Zhuang, Song Yuan, Chuangzhi WuAbstract:The serious K-induced ash problems during biomass Thermal Conversion are closely related to release and transformation behaviors of K. The aim of this work is to explore the contribution of different occurrence forms of K on K release and transformation pathways among various K species during devolatilization of agricultural straw. Devolatilization experiments under different heat treatment conditions (i.e., temperature, heating rate, and atmosphere) were carried out using a fixed-bed apparatus, and occurrence forms of K in the virgin sample and residual chars were quantitatively determined by sequential chemical fraction analysis combined with inductively coupled plasma optical emission spectrometry. Unstable water-soluble K and ion-exchangeable K in wheat straw accounted for about 89.3% of total K and were mainly responsible for the K release. Part of unstable K was directly decomposed into atomic K or sublimated, and a large fraction was first bound to the char matrix to form char–K and then transforme...
