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Yao S.,South China University of Technology | Yao S.,Guangdong Province Key Laboratory of Efficient and Clean Energy Utilization | Shen Y.,Guangdong Electric Power Research Institute | Yin K.,South China University of Technology | And 4 more authors.
Energy and Fuels | Year: 2015

In coal-fired plants, the balance between unburned carbon and NOx emissions stresses the need for rapid and accurate methods for the measurement of unburned carbon. In this paper, molecular CN was adopted to rapidly measure unburned carbon in fly ashes by laser-induced breakdown spectroscopy technique for the first time. The use of molecular CN overcame the interference between the Fe 247.98 and C 247.86 nm lines and the strong diminishing of the C 193.09 nm line intensity in air. Especially, the multivariate regression method combined with the correction of plasma temperature and self-absorption was used to construct calibration model. The performance of the calibration model was evaluated by the quantitative analysis of unkown fly ashes from different types of coal. The results show that the averaged relative error of prediction and the limit of detection are 0.26% and 0.16 wt %, respectively, while the averaged relative standard deviation is less than 5%. The performance of the quantitative analysis of unburned carbon meets the requirement of PRC power industry standard and the most of commercial instruments for online or rapidly analysis of unburned carbon. © 2015 American Chemical Society.


Cao L.,South China University of Technology | Liu J.,South China University of Technology | Liu J.,Guangdong Province Key Laboratory of Efficient and Clean Energy Utilization | Xu X.,South China University of Technology | And 2 more authors.
Huagong Xuebao/CIESC Journal | Year: 2016

Plate-fin heat exchangers (PFHEs) are mostly employed in medium-and small-sized LNG plants. However, works about the heat transfer characteristic optimization of mixed refrigerant in PFHE under low quality have been barely carried out nowadays. Thus, a Linde-Hampson cycle using single stage compressors and recuperative heat exchanger was established and mixed refrigerant (N2-CH4-C2H4-C3H8-iC4H10) was used to obtain the refrigeration temperature of -160℃. Meanwhile, the overall heat transfer coefficient and the correlational influence factor were mainly analysed. The experimental results showed that the overall heat transfer coefficient of the PFHE was about 2.6-22.7 W·m-2·K-1 while the refrigeration temperature and the circulated composition had week influence on the overall heat transfer coefficient. Meanwhile, the existing correlations cannot accurately predict the heat transfer coefficient of the mixed refrigerant under low quality and low flow velocity. However, the correlation of Cavallini and modified Granryd can used to predict the HTC of mixed refrigerant under low quality and low flow velocity after modification in this work. Additionally, some suggestion have been proposed in the design and optimization of PFHEs considering the refrigerate flowrate and pressure drop. © All Right Reserved.


Shi Y.,South China Agricultural University | Gan Y.,South China University of Technology | Gan Y.,Guangdong Province Key Laboratory of Efficient and Clean Energy Utilization
Huagong Xuebao/CIESC Journal | Year: 2016

Charged particles in the flame produced by combustion of hydrocarbon fuels provided an alternative control option via external electric fields. The liquid ethanol was used as fuel. A stainless steel tube with an inner diameter of 0.9 mm was used as the nozzle and an external direct-current electric field was applied. The voltage-current characteristics of a small scale diffusion flames under the electric field were identified. The combustion system can be assumed as an equivalent circuit model. According to the theory of circuit, the change rules of flame equivalent resistance were obtained. The ion production was used as a sensor and a classical simple PID closed control method was used to adjust the flame. The simulation results showed that the system designed in present paper had well anti-jamming capability. The present study can supply some certain guidelines for the control and stable operation of microscale combustor. © All Right Reserved.


Pang W.,South China University of Technology | Liu J.,South China University of Technology | Liu J.,Guangdong Province Key Laboratory of Efficient and Clean Energy Utilization | Xu X.,South China University of Technology
International Journal of Refrigeration | Year: 2016

The performance of the mixed refrigerant (MR) Joule–Thomson cooler is mainly dependent on the MR circulation composition for a given hardware. However, it is difficult to charge the MR to the desired circulation composition, due to the composition shift. In the present study, a novel strategy was proposed to solve this problem. In this strategy, the MR Joule–Thomson cooler is first charged with the initial charge amount, which is obtained by estimating the MR inventory in the cooler using the homogeneous model. Afterwards, the cooler is started and the MR circulation composition is adjusted to the corresponding optimal composition by adding the MR charge amount stepwise. Additionally, this strategy was verified by an experiment with a ternary mixture of methane, ethane and i-butane. The experimental results indicated that the MR circulation composition was able to be adjusted to the corresponding optimal circulation composition approximately within the relative deviation of ±5%. © 2016 Elsevier Ltd and IIR


Gan Y.,South China University of Technology | Gan Y.,Guangdong Province Key Laboratory of Efficient and Clean Energy Utilization | Zhang X.,South China University of Technology | Zhang X.,Guangdong Province Key Laboratory of Efficient and Clean Energy Utilization | And 2 more authors.
Gaodianya Jishu/High Voltage Engineering | Year: 2015

In order to choose the structural design and working parameters of electrostatic spraying combustor reasonably, some experiments of ethanol spraying were carried out and a stable cone-jet mode was obtained based on the new double electrode combustor mainly consisting of a capillary, a ring electrode, and a stainless steel grid. Moreover, the electric field intensity distribution produced by the new double electrode was calculated theoretically. The coupled field of the flow field and electric field was calculated using numerical analysis method. The ethanol-air two-phase flow level set method was used to simulate the flow of ethanol. The stable cone-jet, the electric field intensity distribution near the capillary, and the velocity field of two-phase flow were obtained with the flow rate of 1 mL/h, the capillary voltage of 4.19 kV, and the ring electrode of 1 kV. The minimum flow rate which could form a cone-jet was calculated theoretically. The results show that axial and radial electric field intensity will increase gradually in the internal of the cone-jet, reach the maximum at the interface, and then gradually decrease in the region near to the capillary. The circulation of the velocity vector is found outside the jet-flow, and the flow moves along the tangential direction, which promotes the formation of cone jet. At a certain ring electrode voltage, a stable cone-jet mode will appear when the flow rate of ethanol reaches a minimum value and a suitable voltage is put on the capillary. © 2015, High Voltage Engineering Editorial Department of CEPI. All right reserved.


Gan Y.,South China University of Technology | Gan Y.,Guangdong Province Key Laboratory of Efficient and Clean Energy Utilization | Tong Y.,South China University of Technology | Tong Y.,Guangdong Province Key Laboratory of Efficient and Clean Energy Utilization | And 2 more authors.
TMS Annual Meeting | Year: 2016

Experimental studies of electro-spraying were carried out using ethanol as fuel in a micro-combustor under combined electric field. And the effects of different electro-spraying modes on the combustion efficiency were analyzed. Results showed that when ring electrode potential was invariant, there were four different electro-spraying modes with the variations of nozzle potentials, which were varying with the flow of ethanol. The cone-jet mode was the stablest one during the whole experimental process. The atomized ethanol was ignited and combusted stably near the steel mesh, the combustion efficiency increased firstly and then decreased along with the increasing of the equivalent ratios, reached the maximum values when the equivalent ratio equal to 1.0. And the maximum values were the highest at the cone-jet mode, and the lowest at the pulsed-jet mode.


Fan Y.,Guangdong Province Key Laboratory of Efficient and Clean Energy Utilization | Yu Z.,South China University of Technology | Fang S.,Guangdong Province Key Laboratory of Efficient and Clean Energy Utilization | Lin Y.,Guangdong Province Key Laboratory of Efficient and Clean Energy Utilization | And 2 more authors.
Energy Conversion and Management | Year: 2016

The aim of this study is trying to reveal the thermal characteristics and kinetics of oil shale, municipal solid waste and their blends in the combustion process which are needed for efficient utilization. The combustion experiment is carried out in a thermogravimetric simultaneous thermal analyzer, where the temperature ranged from 110 °C to 900 °C at three different heating rates as 10 °C/min, 20 °C/min and 30 °C/min. Their kinetics were studied by Ozawa-Flynn-Wall and Friedmen methods. According to the data analysis, combustion characteristic index increased progressively with the increase of the proportion of municipal solid waste. And it's suggested that there was certain interaction in the combustion process of oil shale and municipal solid waste. The average activation energy of the blends reached the minimum value, 177.7927 kJ/mol by Ozawa-Flynn-Wall method and 167.4234 kJ/mol by Friedmen method, when the proportion of MSW was 70%. © 2016 Elsevier Ltd. All rights reserved.


Fang S.,Guangdong Province Key Laboratory of Efficient and Clean Energy Utilization | Yu Z.,South China University of Technology | Lin Y.,Guangdong Province Key Laboratory of Efficient and Clean Energy Utilization | Hu S.,Guangdong Province Key Laboratory of Efficient and Clean Energy Utilization | And 2 more authors.
Energy Conversion and Management | Year: 2015

The pyrolysis characteristics of municipal solid waste (MSW), paper sludge (PS) and their blends were studied through a thermogravimetric simultaneous thermal analyzer from room temperature to 1000 °C. Meanwhile their kinetics were studied by Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) methods. The mass proportions of PS in the blends were 10%, 30%, 50%, 70%, 90%, respectively and the experiments were carried out at different heating rates (30, 40 and 50 °C/min). The initial temperature of MSW was lower than that of PS and the terminated temperature was higher than PS. The comprehensive characteristic index decreased progressively along with the decrease of the MSW proportion. The values of average activation energies calculated by FWO and KAS methods were highly consistent. The average activation energy reached the minimum number, 96.7 kJ/mol by KAS and 11.56 kJ/mol by FWO, with the proportion of PS was 50%. © 2015 Elsevier Ltd. All rights reserved.


Cai Z.,South China University of Technology | Ma X.,South China University of Technology | Fang S.,Guangdong Province Key Laboratory of Efficient and Clean Energy Utilization | Yu Z.,South China University of Technology | Lin Y.,Guangdong Province Key Laboratory of Efficient and Clean Energy Utilization
Applied Thermal Engineering | Year: 2016

The thermal behavior of eucalyptus residues (ER), paper mill sludge (PMS) and their blends during combustion processes was investigated in this study. Blending ranging from 10 wt% to 90 wt% on dosage ratio were prepared to study their co-combustion behaviors and kinetics. The experiments were conducted in a differential thermogravimetric analyzer at different heating rates (10, 20 and 40 °C/min), at temperature ranging from 120 °C to 950 °C and in 80% nitrogen/20% oxygen atmosphere. The comprehensive characteristic index decreased with the increase of the PMS ratio. Adding ER to PMS may improve the combustion characteristics of PMS. The value of average activation energy obtained by Kissinger-Akahira-Sunose (KAS) and Starink methods did not gradually decline with the increasing proportion of PMS in the blends. The average activation energy reached the minimum number when the percentage of PMS was 10%, which was 159.30 kJ/mol by KAS and 160.36 kJ/mol by Starink, respectively. © 2016 Elsevier Ltd All rights reserved.


Xu X.,South China University of Technology | Xu X.,Guangdong Province Key Laboratory of Efficient and Clean Energy Utilization | Liu J.,South China University of Technology | Cao L.,South China University of Technology
Chinese Journal of Chemical Engineering | Year: 2015

Auto cascade refrigeration (ACR) cyclewith phase separators iswidely used in the cryogenic system. The composition of mixed refrigerant has a great effect on the performance of the system. Based on the assumption of infinite volume of phase separator, ACR systemwith one phase separator is simulated in this paper. The variation of refrigerant composition under different valves opening is obtained. A related experimental systemis set up to verify the variation. The result shows that when the valve opening connected to the evaporator increases or the valve opening under the phase separator decreases, the low-boiling component concentration of the working mixture passing through the compressor and condenser increases, while the high-boiling component concentration decreases. Furthermore, the variations of condensation pressure and evaporation pressure under different valves opening are also observed. This paper is helpful to deepen the understanding of ACR system. © 2014 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. All rights reserved.

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