• Energy Research
• Closed Access close
• Open Source close
• Embargo close
• other engineering and technologies close
• AU close

Short-term generation scheduling is an important function in daily operational planning of power systems. It is defined as optimal scheduling of power generators over a scheduling period while respecting various generator constraints and system constraints. Objective of the problem includes costs associated with energy production, start-up cost and shut-down cost along with profits. The resulting problem is a large scale nonlinear mixed-integer optimization problem for which there is no exact solution technique available. The solution to the problem can be obtained only by complete enumeration, often at the cost of a prohibitively computation time requirement for realistic power systems. This paper presents a hybrid algorithm which combines Lagrangian Relaxation (LR) together with Evolutionary Algorithm (EA) to solve the problem in cooperative and competitive energy environments. Simulation studies were carried out on different systems containing various numbers of units. The outcomes from different algorithms are compared with that from the proposed hybrid algorithm and the advantages of the proposed algorithm are briefly discussed.

Abstractπ‐Conjugated polyelectrolytes (CPEs) have been studied as interlayers on top of a separate hole transport layer (HTL) to improve the wetting, interfacial defect passivation, and crystal growth of perovskites. However, very few CPE‐based HTLs have been reported without rational molecular design as ideal HTLs for perovskite solar cells (PeSCs). In this study, the authors synthesize a triphenylamine‐based anionic CPE (TPAFS‐TMA) as an HTL for p‐i‐n‐type PeSCs. TPAFS‐TMA has appropriate frontier molecular orbital (FMO) levels similar to those of the commonly used poly(bis(4‐phenyl)‐2,4,6‐trimethylphenylamine) (PTAA) HTL. The ionic and semiconducting TPAFS‐TMA shows high compatibility, high transmittance, appropriate FMO energy levels for hole extraction and electron blocking, as well as defect passivating properties, which are confirmed using various optical and electrical analyses. Thus, the PeSC with the TPAFS‐TMA HTL exhibits the best power conversion efficiency (PCE) of 20.86%, which is better than that of the PTAA‐based device (PCE of 19.97%). In addition, it exhibits negligible device‐to‐device variations in its photovoltaic performance, contrary to the device with PTAA. Finally, a large‐area PeSC (1 cm2) and mini‐module (3 cm2), showing PCEs of 19.46% and 18.41%, respectively, are successfully fabricated. The newly synthesized TPAFS‐TMA may suggest its great potential as an HTL for large‐area PeSCs.

Abstract Background Parabolic Trough Solar Collector (PTSC) is one of the most popular and an effective device that converts solar radiation into a heat or useful energy. However, it suffers from high temperature gradient and low thermal efficiency. The solution for this problem is to use new advanced coolants (hybrid nanofluids) in order to enhance PTSC's thermal efficiency. Methods A numerical analysis on the thermo-hydraulic performance of a PTSC receiver's tube equipped with conical turbulators is presented. The Navier-Stokes equations are solved using Finite Volume Method (FVM) coupled with Monte Carlo Ray Tracing (MCRT) method. The flow and thermal characteristics as well as entropy generation of the PTSC's receiver tube are investigated for three hybrid nanofluids (Ag-SWCNT, Ag-MWCNT, and Ag-MgO) having a mixing ratio of (50:50) dispersed in Syltherm oil 800, Reynolds number (5000 to 100,000) and fluid inlet temperatures (400 to 650 K). Significant findings The conical turbulators effectively augmented the thermal performance by 233.4% utilising Ag-SWCNT/Syltherm oil instead of pure Syltherm oil. The performance evaluation criterion is found to be in the range of 0.9–1.82. The thermal and exergetic efficiencies increased by 11.5% and 18.2%, respectively. The maximum decrement in the entropy generation rate and entropy generation ratio are 42.7% and 33.7%.

Abstract A new conical-cylindrical top-discharge blow tank is designed, by introducing the pulsed gas to facilitate discharging, for stable transportation for kaolin powders. A series of experimental studies on pulsed gas characteristic parameters like pulsed gas flow rate Qpulsed (5 m3/h ≤ Qpulsed ≤ 25 m3/h), pulsed interval tpulsed (1 s ≤ tpulsed ≤ 5 s) and pulsed width τpulsed (50 ms ≤ τpulsed ≤ 250 ms) are conducted with the fluidized gas flow rate of 12 m3/h. The experiments mainly test the powder mass flow rate and solid-gas ratio in the conveying process. The results indicate that the mass flow rate and solid-gas ratio range 12.6–278.04 kg/h and 0.9–19.56 kg/m3, respectively. With the increase of the pulsed gas flow rate, the mass flow rate and solid gas ratio first increase and then decrease. When the ratio of fluidized gas flow rate to pulsed gas flow rate is within 0.8–1.2, its conveying capacity reaches the maximum. Meanwhile, the increase in the pulsed interval leads to the decrease of the mass flow rate and solid-gas ratio. Moreover, the increase in the pulsed width leads to the initial increase and then the stabilization of the mass flow rate and solid gas ratio. When the pulsed width is 50 ms, the improvement of discharge would small. Conversely, increasing the pulsed width can increase the discharge, and stabilize subsequently until over 200 ms. Besides, moisture content is one of the important factors affecting kaolin powders discharge. When the moisture content is 0.83%, the pulsed gas does not improve the discharge significantly. Meanwhile, pressure distribution at different locations in the tank is also measured. The results reveal that the introduction of pulsed gas changes the pressure distribution in the tank. A pressure zone is formed on the upper part of the tank, which promotes the powder discharge.

Abstract To achieve optimal generation from a number of mixed power plants by minimizing the operational cost while meeting the electricity demand is a challenging optimization problem. When the system involves uncertain renewable energy, the problem has become harder with its operated generators may suffer a technical problem of ramp-rate violations during the periodic implementation in subsequent days. In this paper, a scenario-based dynamic economic dispatch model is proposed for periodically implementing its resources on successive days with uncertain wind speed and load demand. A set of scenarios is generated based on realistic data to characterize the random nature of load demand and wind forecast errors. In order to solve the uncertain dispatch problems, a self-adaptive differential evolution and real-coded genetic algorithm with a new heuristic are proposed. The heuristic is used to enhance the convergence rate by ensuring feasible load allocations for a given hour under the uncertain behavior of wind speed and load demand. The proposed frameworks are successfully applied to two deterministic and uncertain DED benchmarks, and their simulation results are compared with each other and state-of-the-art algorithms which reveal that the proposed method has merit in terms of solution quality and reliability.

This paper investigates the intact and damage survivability of a floating–moored Oscillating Water Column (OWC) device using physical model experiments and Computational Fluid Dynamics (CFD) simulations. Different extreme wave conditions have been tested using irregular and regular wave conditions. The device was moored to the tank floor via four vertical taut lines and the effect of the mooring line pre–tension on the device response was studied. It was found that the instantaneous position of the floating device was a key factor in the survivability analysis such that a certain irregular wave train that might not include the largest wave could induce the maximum response. Reducing the pre–tension minimized the maximum surge, but significantly increased the maximum tension due to mooring slack events causing snatch loads. A design regular wave with a period equal to the peak period and a height of 1.9–2.0 times the significant wave height could reasonably predict the same maximum line tension as the irregular sea state, but a smaller wave height was required to achieve the maximum surge. A single failure in the mooring system increased the maximum tension by 1.55 times the intact tension. For a damaged mooring system, using the same design regular wave condition derived from the survivability analysis with an intact mooring system could result in overestimating the maximum tension by more than 20% in comparison to the tension from the irregular sea state, but a smaller regular wave height or a different regular wave condition representing another sea state could lead to the same maximum tension. This highlighted the importance of investigating survival conditions with a damaged mooring system instead of simply using the same conditions derived for the intact mooring system.

Abstract Mixing behavior of binary particles with different densities in a wet fluidized bed has been experimentally investigated in this work. Some important hydrodynamic characteristics during mixing, such as the minimum fluidization velocity, flow pattern, and flotsam particle distribution are measured. The differences between dry and wet particles are systematically compared. It is found that the minimum fluidization velocity Umf of wet particles is higher than that of dry particles due to the liquid bridge force between particles. Umf reaches its maximum when the liquid saturation S = 0.1, and then decreases, and does not change much when the liquid saturation in the region of S = 0.2–0.3. Liquid addition can bring two opposite effects on the mixing of a binary mixture of particles with different densities. First, the intensity of bubbling in the wet fluidized bed is lower than that in the dry fluidized bed at the same operation gas velocity Uf, which will weaken the mixing. Secondly, the liquid bridge forces between particles can restrain the density segregation, which is beneficial for mixing. A simple method is developed based on the analysis of forces on flotsam particles to evaluate the effect of liquid bridge force on mixing. A segregation index Se, defined as Se = Flift/Fresis, where Flift contains the drag force Fd and buoyancy force Fb, and Fresis contains the gravitation force Fg and liquid bridge force Flb, is used to indicate the segregation potential. The calculated results show that Se > 1 in the dry fluidized bed and Se

Abstract Comprehensive information about the concentrations, distribution, and modes of occurrence of elements in coal are important from the environmental and economic point of view. Although a great number of previous studies have investigated the geology of coalbed methane in the Qinshui Basin, only a few studies focused on the inorganic constituents in coal. More specifically, the mode of occurrences of valuable element Li in the No. 3 Coal is still unclear, although Li was found enriched. In this study, we present mineral characteristics, as well as multi-element data on the Permian No. 3 Coal from the Sucun and Gaohe Mines, Changzhi City, southern Qinshui Basin. The studied coals are characterized by low- to medium-ash yield (Ad = 5.72%- 28.18%, 12.34% on average), low volatile matter yield (Vdaf = 8.49–15.17%, 10.96% on average), suggesting a low volatile bituminous coal to semi-anthracite. NH4-illite and kaolinite are the main minerals in the coals detected by XRD, and trace amount of minerals calcite, dolomite, quartz, pyrite and diaspore can also be found. The major elements of the studied No. 3 coals are dominated by SiO2 and Al2O3, ranging 2.49–16.45 wt% and 2.13–12.9 wt% (on a whole-coal basis), respectively. Li is enriched in the No. 3 coals (5