International Journal of Energy Research

In this paper, a new simultaneous framework of distribution network operation is proposed based on the scheduling of photovoltaic/wind/battery multi-microgrids with network reconfiguration considering self-healing. The objective function is considered to minimize the energy losses, and multi-microgrids cost and improve the reliability indices including minimization of energy not-supplied (ENS) and minimizing system average interruption duration (SAIDI) and system average interruption frequency (SAIFI) indices. The optimization variables are defined as the situation of the distribution network switches to find the network’s optimal configuration with the installation location and size of renewable resources and battery energy storage during 24 hours. An improved beluga whale optimization (IBWO) based on a nonlinearly diminishing inertia weight (NDIW) approach is used to find the optimal variable set of the problem. The recommended methodology is implemented on 33-bus and real 59-bus distribution networks. The results demonstrated that by obtaining an optimal state of the network switches in the event of a fault, as well as the optimal scheduling of the two microgrids, the energy losses have decreased and the reliability indices have improved. The outcomes of the proposed methodology based on the hybrid multi-microgrid allocation and network reconfiguration are stated that the losses, ENS, SAIDI, and SAIFI are reduced by 66.39%, 54.00%, 50.24%, and 33.61%, respectively, for 33-bus network and are declined by 65.29%, 57.44%, 48.63%, and 62.33%, respectively, for the real 59-bus Ahvaz network in comparison with the base network. The obtained results illustrated that in the condition of the network line outage, by simultaneously implementing the reconfiguration with the change of network switches and the optimal allocation and scheduling of HMGs in the network, self-healing is provided to prevent a significant weakening of the network performance so that the resilience is improved in addition to minimizing the energy losses and the cost of HMG energy injection compared to the base network. The findings revealed that the objectives including losses, ENS, SAIFI, and SAIDI are increased by 78.29%, 33.00%, 83.33%, and 35.11%, respectively, due to outage of line 22 of the 33-bus network and these objectives are increased by 52.32%, 10.30%, 32.29%, and 79.66%, respectively, due to outage of line 12 of the 59-bus network compared with not considering the line outage. Moreover, the superior capability of the recommended NDIW-based IBWO has been confirmed in comparison with the well-known particle swarm optimizer (PSO) and ant lion optimizer (ALO) in solving the problem to achieve better objective value.

We conducted an experimental study on the condensation heat transfer and droplet dynamics on multiple horizontal copper tubes with superhydrophobic characteristics. Condensation heat transfer has various industrial applications such as power plants and air-conditioning systems. Because condensers are typically designed in multiple-tube configurations, studying the phenomenon of multiple tubes is important. We investigated the effect of a superhydrophobic surface modification, which induces dropwise condensation, on the heat transfer performance of multiple-tube condensers. The purpose of this research is to evaluate the extent to which heat transfer performance is improved by comparing superhydrophobic tubes with bare tubes and to analyze the impact of droplet dynamics on heat transfer performance. The results show that the heat transfer coefficient of the superhydrophobic tubes is improved by approximately 9.5%–44.9% compared to that of bare tubes. Droplet dynamic analysis revealed differences in droplet behavior between the superhydrophobic tubes and bare tubes, including the formation of droplets by condensation, the process of droplets falling on the tube surface, and the impact of droplets falling on other tubes in a multiple-tube configuration. Based on these results and observations, it can be concluded that the heat transfer performance of the superhydrophobic tube is superior to that of the bare tube. The droplet dynamic analysis demonstrated that the droplets formed on the superhydrophobic surface could be easily removed by the flow, leading to more efficient heat transfer. These findings highlight the potential for more efficient heat transfer in multiple tubes through superhydrophobic modifications.

In this study, a new and facile process was developed for the preparation of composite catalysts based on tungsten oxide (WO₃) by batch reactor routes. The structures, morphologies, compositions, and characteristics of synthesized materials were investigated and confirmed. Using batch reactor processes, WO₃ nanorods (WO₃ NR), heterostructures of WS₂/WO₃ nanobricks (WS₂/WO₃ NB), and WS₂/WO₃ nanorods (WS₂/WO₃ NR) were successfully prepared. The prepared materials were then employed for hydrogen evolution reaction (HER) to investigate their catalytic performance. The results indicated that the electrocatalytic activities of WS₂/WO₃ NR are significantly improved compared to those of WO₃ NR and WS₂/WO₃ NB. This improvement could be attributed to the formation of heterostructure between WS₂ and WO₃ elements in highly uniform materials, which could create the synergistic effect and further improve the catalytic activities of the catalyst. The data shows that the Tafel slope of WS₂/WO₃ NR (82.7 mV dec⁻¹) is significantly lower than that of WO₃ NR (112.5 mV dec⁻¹) and WS₂/WO₃ NB (195.5 mV dec⁻¹). Furthermore, the resistance of WS₂/WO₃ NR (397.7 Ω) is markedly decreased compared to those of WO₃ NR (1816 Ω) and WS₂/WO₃ NB (3597 Ω). The results indicate that WS₂/WO₃ NR could be a great catalyst for electrochemical applications.

Transition metal oxides are considered alternative electrocatalysts for ZAB owing to their multiple oxidation states. However, they have limitations such as low electrical conductivity and the deficiency of reactive sites. In this study, to overcome these shortcomings and improve electrocatalytic activity, oxygen vacancies and porous architectures were introduced through a partial reduction process and a porous carbon framework. Open porous carbon microspheres with uniformly loaded NiCo₂O₄ nanosheets and oxygen vacancies (V-NCO/OPC) displayed enhanced electrocatalytic performance with a low Tafel slope (68 mV dec^-1) in the oxygen reduction reaction (ORR) and a low overpotential (402 mV) at 10 mA cm^–2 in the oxygen evolution reaction (OER). The combined effect of the oxygen vacancies and porous architecture can offer sufficient active sites, modify the electronic structure of the metal oxide surface, and facilitate mass transport, enhancing the electrocatalytic properties of V-NCO/OPC. Furthermore, when applied for ZAB, V-NCO/OPC demonstrated better electrochemical performance including discharge power density (154.9 mW cm^-2) at the current density of 175.9 mA cm^-2, low voltage gap (0.85 V) at the initial cycle, and long-term (250 h) cycle stability at the current density of 10 mA cm⁻² than those of noble-metal electrocatalysts.

Optimal sizing and management of hybrid wind turbine-diesel-battery system for reverse osmosis seawater desalination in NEOM city is the objective of the paper. Therefore, the paper explored the different factors to optimize and introduce a technoeconomic evaluation and energy management of a stand-alone wind turbine (WT) system, diesel generator (DG), and battery storage (BS). The suggested WT/DG/BS system is implemented to feed seawater reverse osmosis (SWRO) unit in NEOM. The necessitated desalinated water per day is 100 m³. To determine the optimal size of WT/DG/BS corresponding to the minimum cost of energy (COE) and net present cost, two different ratings of the SWRO units (SWRO-100 and SWRO-150), three control dispatch strategies (load following, cycle charging, and combined dispatch), and five types of batteries are considered. HOMER software is performed to simulate and optimize the WT/DG/BS. The optimization results indicated that the best battery storage is the Trojan SAGM battery. In this case, the COE ranged between $0.337/kWh and $0.564/kWh. The lowest COE of $0.377/kWh is obtained when using a combined control strategy and SWRO-100 unit, whereas the worst COE of $0.564/kWh is obtained when using load following control strategy and SWRO-150 unit. The best option of the WT/DG/BS system to supply the SWRO unit is option number 26. This system includes one wind turbine of 90 kW, DG of 25 kW, 47 Trojan SAGM batteries, a 23.8 kW converter, a SWRO-100 unit, and a combined control strategy. The net present cost and the initial cost are $950,725 and $221,495, respectively. The annual operating cost and annual consumed fuel are $56,409 and 36,396 L, respectively. Compared with using only a 25 kW diesel generator, the COE reduced from $0.373/kWh (using only DG/BS) to $0.337/kWh (using the best option) by around 9.65%. Under this condition, the values for the internal rate of return, return on investment, and simple payback are 11%, 7.8%, and 8.3 years, respectively.

Triboelectric nanogenerators (TENGs) are promising energy-harvesting devices that generate electricity from mechanical energy. However, the electrical outputs of typical TENGs are limited because of the fundamental mechanism by which TENGs require a certain amount of space for contact-separation motion. Therefore, we developed an origami-based vertical/fluttering hybrid TENG (OVFH-TENG), which is the innovative structure that can generate electricity from both vertical movement and wind flow which is generated by vertical movement. It consists of a vertical TENG and a fluttering TENG where vertical TENGs can generate electricity and wind flow from mechanical input and the fluttering TENGs can generate electricity from the wind flow which is generated by its own operation process. Thus, OVFH-TENG can effectively harvest energy from vertical contact and fluttering motions with a single input. The optimized OVFH-TENG generated a 34.7% higher output than the general contact-separation TENG. Finally, the OVFH-TENG was able to light 180 LEDs, which was not possible with a general contact-separation TENG.