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Experimental investigation and feasibility analysis of a thermophotovoltaic cogeneration system in high-temperature production processes
Jianxiang WANG, Hong YE, Xi WU, Hujun WANG, Xiaojie XU
Front Energ. 2013, 7 (2): 146-154.
https://doi.org/10.1007/s11708-013-0253-y
The experimental I-V characteristics of a Si cell module in a thermophotovoltaic (TPV) system were investigated using SiC or Yb2O3 radiator. The results demonstrate that the short-circuit current increases while the open-circuit voltage, along with the fill factor, decreases with the cell temperature when the radiator temperature increases from 1273 to 1573 K, leading to a suppressed increase of the output power of the system. The maximum output power density of the cell module is 0.05 W/cm2 when the temperature of the SiC radiator is 1573 K, while the electrical efficiency of the system is only 0.22%. The efficiency is 1.3% with a Yb2O3 radiator at the same temperature, however, the maximum output power density drops to 0.03 W/cm2. The values of the open-circuit voltage and the maximum output power obtained from the theoretical model conform to the experimental ones. But the theoretical short-circuit current is higher because of the existence of the contact resistance inside the cell module. In addition, the performance and cost of TPV cogeneration systems with the SiC or Yb2O3 radiator using industrial high-temperature waste heat were analyzed. The system electrical efficiency could reach 3.1% with a Yb2O3 radiator at 1573 K. The system cost and investment recovery period are 6732 EUR/kWel and 14 years, respectively.
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A review of recent experimental investigations and theoretical analyses for pulsating heat pipes
Xin TANG, Lili SHA, Hua ZHANG, Yonglin JU
Front Energ. 2013, 7 (2): 161-173.
https://doi.org/10.1007/s11708-013-0250-1
Pulsating heat pipe (PHP), or oscillating heat pipe (OHP), a novel type of highly efficient heat transfer component, has been widely applied in many fields, such as in space-borne two-phase thermal control systems, in the cooling of electronic devices and in energy-saving technology, etc. In the present paper, the characteristics and working principles of the PHPs are introduced and the current researches in the field are described from the viewpoint of experimental tests, theoretical analyses as well as practical applications. Besides, it is found that the state-of-the-art experimental investigations on the PHPs are mainly focused on the flow visualization and the applications of nanofluids and other functional fluids, aiming at enhancing the heat transfer performance of the PHPs. In addition, it is also pointed out that the present theoretical analyses of the PHP are restricted by further development of two-phase flow theories, and are concentrated in the non-linear analyses. Numerical simulations are expected to be another research focus, in particular of the combination of the nanofluids and functional fluids.
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Constriction factor based particle swarm optimization for analyzing tuned reactive power dispatch
Syamasree BISWAS(RAHA), Kamal Krishna MANDAL, Niladri CHAKRABORTY
Front Energ. 2013, 7 (2): 174-181.
https://doi.org/10.1007/s11708-013-0246-x
The reactive power dispatch (RPD) problem is a very critical optimization problem of power system which minimizes the real power loss of the transmission system. While solving the said problem, generator bus voltages and transformer tap settings are kept within a stable operating limit. In connection with the RPD problem, solving reactive power is compensated by incorporating shunt capacitors. The particle swarm optimization (PSO) technique is a swarm intelligence based fast working optimization method which is chosen in this paper as an optimization tool. Additionally, the constriction factor is included with the conventional PSO technique to accelerate the convergence property of the applied optimization tool. In this paper, the RPD problem is solved in the case of the two higher bus systems, i.e., the IEEE 57-bus system and the IEEE 118-bus system. Furthermore, the result of the present paper is compared with a few optimization technique based results to substantiate the effectiveness of the proposed study.
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Comparison of optimal capacitor placement methods in radial distribution system with load growth and ZIP load model
Veera Venkata Satya Naryana MURTY, Ashwani KUMAR
Front Energ. 2013, 7 (2): 197-213.
https://doi.org/10.1007/s11708-013-0249-7
In this paper, a combined power loss sensitivity (PLS) index-based approach is proposed to determine the optimal location of the capacitors in the radial distribution system (RDS) based on the real and reactive combined loss sensitivity index, as capacitor placement not only reduces real power loss with voltage profile improvement but also reduces reactive power loss due to the reactive power compensation in the network. The results have been obtained with the existing methods of power loss index (PLI) and index vector (IV) method for comparison. Besides, the optimal placement has been obtained with the proposed method as well as existing methods and the total kVar support has been obtained. In addition, the results of net cost savings for the 10-, 34-, and 69-bus systems are obtained for comparison. Moreover, the results have been obtained for a large system of 85 buses to validate the results with combined sensitivity based approach. Furthermore, the load growth factor has been considered in the study which is essential for the planning and expansion of the existing systems, whereas the impact of the realistic load model as ZIP load model has been considered for the study of all the systems.
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Correlations for estimating solar radiation using sunshine hours and temperature measurement in Osogbo, Osun State, Nigeria
O. S. OHUNAKIN, M. S. ADARAMOLA, O. M. OYEWOLA, R. O. FAGBENLE
Front Energ. 2013, 7 (2): 214-222.
https://doi.org/10.1007/s11708-013-0241-2
In this study, the global solar radiation on horizontal surface in Osogbo, Osun state, Nigeria was analyzed using 11-year data (1997–2007). Correlations using linear and quadratic expressions were developed to relate the global solar radiation on horizontal surface based on relative sunshine hours and temperature measurements for evaluating the monthly average daily global solar radiation. The calculated monthly clearness index values indicate that the prevailing weather condition in Osogbo is heavily overcast. All the developed quadratic correlations gave better correlation coefficients (0.834, 0.872 and 0.823 respectively) than the linear models. However, the Hargreaves and Samani related based quadratic model gave the best among the three developed quadratic expressions and is therefore suggested for estimating the monthly global radiation in this site and its surroundings.
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A solution to the unit commitment problem—a review
B. SARAVANAN, Siddharth DAS, Surbhi SIKRI, D. P. KOTHARI
Front Energ. 2013, 7 (2): 223-236.
https://doi.org/10.1007/s11708-013-0240-3
Unit commitment (UC) is an optimization problem used to determine the operation schedule of the generating units at every hour interval with varying loads under different constraints and environments. Many algorithms have been invented in the past five decades for optimization of the UC problem, but still researchers are working in this field to find new hybrid algorithms to make the problem more realistic. The importance of UC is increasing with the constantly varying demands. Therefore, there is an urgent need in the power sector to keep track of the latest methodologies to further optimize the working criterions of the generating units. This paper focuses on providing a clear review of the latest techniques employed in optimizing UC problems for both stochastic and deterministic loads, which has been acquired from many peer reviewed published papers. It has been divided into many sections which include various constraints based on profit, security, emission and time. It emphasizes not only on deregulated and regulated environments but also on renewable energy and distributed generating systems. In terms of contributions, the detailed analysis of all the UC algorithms has been discussed for the benefit of new researchers interested in working in this field.
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Transient emission simulation and optimization of turbocharged diesel engine
Lingge SUI, Zhongchang LIU, Yongqiang HAN, Jing TIAN
Front Energ. 2013, 7 (2): 237-244.
https://doi.org/10.1007/s11708-013-0251-0
In order to alleviate the pressure of experimental research of turbocharged diesel engine under transient operations, a whole process simulation platform for turbocharged diesel engine under transient operations was established based on the multi-software coupling technologies of Matlab/Simulink, GT-Power, STAR-CD and artificial neural network. Aimed at the contradiction of NOx and soot emission control with exhaust gas recirculation (EGR) of turbocharged diesel engine under transient operations, on this simulation platform, a transient EGR valve control strategy was proposed, which adjusted the EGR valve in adjacent level based on the feedback of its opening according soot control limit under transient operations. Simulation and experimental results prove that the transient emission optimization effect of this control strategy is obvious. On the one hand, compared with the previous control strategy, which closed the EGR valve during the whole transient operations, soot emission is slightly increased by 9.5%, but it is still 9% lower than the control limit. On the other hand, compared with the previous control strategy, NOx transient emission is reduced by 44%.
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Load frequency control in deregulated power system with wind integrated system using fuzzy controller
Yajvender Pal VERMA, Ashwani KUMAR
Front Energ. 2013, 7 (2): 245-254.
https://doi.org/10.1007/s11708-012-0218-6
This paper presents the analysis of load frequency control (LFC) of a deregulated two-area hydro-thermal power system using fuzzy logic controller, with doubly fed induction generators (DFIGs) integrated into both the control areas. The deregulation of power sector has led to the formation of new companies for generation, transmission and distribution of power. The conventional two-area power system is modified to study the effects of the bilateral contracts of companies on the system dynamics. Deregulation creates highly competitive and distributed control environment, and the LFC becomes even more challenging when wind generators are also integrated into the system. The overall inertia of the system reduces, as the wind unit does not provide inertia and isolates from the grid during disturbances. The DFIGs integrated provide inertial support to the system through modified inertial control scheme, and arrests the initial fall in frequency after disturbance. The inertial control responds to frequency deviations, which takes out the kinetic energy of the wind turbine for improving the frequency response of the system. To enhance the participation of the doubly fed induction generator (DFIG) in the frequency control, optimal values of the speed control parameters of the DFIG-based wind turbine have been obtained using integral square error (ISE) technique. The dynamics of the system have been obtained for a small load perturbation, and for contract violation using fuzzy controller.
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Numerical simulation of combustion characteristics at different coal concentrations in bituminous coal ignition in a tiny-oil ignition burner
Chunlong LIU, Qunyi ZHU, Zhengqi LI, Qiudong ZONG, Yiquan XIE, Lingyan ZENG
Front Energ. 2013, 7 (2): 255-262.
https://doi.org/10.1007/s11708-013-0255-9
With the objective of producing a full-scale tiny-oil ignition burner, identical to the burner used in an 800 MWe utility boiler, numerical simulations were performed using Fluent 6.3.26 to study the progress of ignition for four coal concentration settings covering sub-operation conditions prevailing during the experiments performed with the burner. The numerical simulations conformed to the experimental results, demonstrating the suitability of the model used in the calculations. Simulations for a coal concentration of 0.40 kg/kg corresponding to a single burner operating at its rated output were also conducted, which indicated that gas temperatures along the burner centerline were high. As gas flowed to the burner nozzle, the high-temperature region expanded, ensuring a successful pulverized-coal ignition. With increasing coal concentration (0.08–0.40 kg/kg), the gas temperature along the burner centerline and at the first and second combustion chamber exits decreased at the equivalent radial points. At the center of the second combustion chamber exit, the O2 concentrations were almost depleted for the five coal concentrations, while the CO concentrations peaked.
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