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• The fuel cell/engine/battery hybrid power system with methanol is proposed. • The generation efficiency and fuel consumption peaked at 58.36 % and 283.19 g/kWh. • The carbon reduction of the system for a single voyage is 606.46 tons. • The effects of the main parameters on the system performance were evaluated. The adoption of alternative fuels and high-efficiency power systems has the potential to significantly reduce carbon emissions in maritime transportation. However, there is currently limited understanding of how new power forms affect the effective payload during actual ship operations. This study proposes a hybrid power system using methanol as fuel, integrating solid oxide fuel cells, an engine, and batteries. A mathematical model of the system was established using a modular modeling approach, and the system's performance was evaluated based on container ship scenarios. The results demonstrate that under no-refueling conditions, the hybrid power system achieves a high electrical efficiency of 58.36 %, a fuel consumption rate of 283.19 g/kWh, and carbon emissions of 389.39 g/kWh. Increasing the operating temperature and reducing the current density can enhance the thermodynamic performance of the solid oxide fuel cell and the system, with electrical efficiency exceeding 60 %. Solid oxide fuel cells exhibit poor load variation characteristics, taking approximately 200 s for their output voltage to decrease from 0.62 V to 0.57 V. In contrast, lithium batteries demonstrate rapid load response characteristics. For a single voyage, the ship requires 835.776 tons of fuel, resulting in an increase of 284.776 tons compared to diesel engines. However, carbon emissions are reduced by 606.46 tons. It is noteworthy that the weight and volume of the hybrid power system depend on the power distribution between the fuel cell and the engine. In summary, this innovative hybrid power system provides a potent means of significantly reducing carbon emissions in the shipping industry. [ABSTRACT FROM AUTHOR]

Highlights • A STEG system with spray cooling was established. • Compared with water cooling, the spray cooling can make better performance. • There exits optimal operating parameters which can max the generating efficiency. • The effects of structural and physical parameters were analyzed. Abstract Use of an efficient cooling system is critical from the performance viewpoint of solar thermoelectric generation (STEG) systems. This study proposes the use of spray cooling as an effective technique for use in applications involving STEG systems. A mathematical model has been established to analyze STEG systems from the perspective of net generating efficiency and output power. Results demonstrate that compared to water-cooling, use of the spray-cooling technique results in enhanced generating efficiency, especially under high concentration ratios, owing to inherent advantages, such as high heat transfer performance, low power consumption, and no contact resistance. At a concentration ratio of roughly 200, the net generating efficiency when using spray cooling was observed to be 31.3% higher compared to that achieved when using water cooling. Under conditions of fixed module parameters and structure, there exist optimum values of the spray flow rate and concentration ratio that result in maximization of the net generating efficiency of STEG systems. This maximum efficiency of 13.203% occurs at a concentration ratio of 165 and corresponding flow rate of 0.35 L·min−1, at ZT = 1. Additionally, the net generating efficiency can be further enhanced by reducing the temperature of cooling water. The structural parameter γ is proposed to characterize the geometry of the thermoelectric module. As observed, there exists an optimum value of γ as well that tends to maximize the net generating efficiency of the system. Moreover, this optimum value of γ gradually increases with increase in concentration ratio. Results also demonstrate that optimum values of the spray flow rate and concentration ratio follow an approximately linear increase with increase in the ZT value of STEG modules. [ABSTRACT FROM AUTHOR]

Multi-energy systems (MESs) integrate multiple energy vectors and contribute to energy efficient utilization, which have received considerable attention in the energy research field. However, regarding a MES with multi communities, the coordination among the communities has not been fully considered in its planning and configuration. Therefore, this paper proposes a coordinated configuration strategy for MES planning based on capacity-energy-information sharing. First, analysing the capacity, energy and information sharing mechanisms among communities, an improved energy hub (EH) model and hierarchical planning framework for MES is built. Moreover, a bilevel configuration model that coordinates the planning and operation stages is developed to design a MES, which is guided by the information sharing of communities. While the upper level model makes the optimal quantity and capacity configuration plan of communities with consideration of capacity sharing, the lower level model optimizes the best operation economy considering energy interactions in MES scheduling. Finally, a case study is carried out and simulation results show that, compared with the planning approaches in the reference cases, the proposed strategy contributes to a decrease in the MES planning costs and exhibits better performances in jointly considering the planning economy, robustness, carbon emissions and user benefits. • A MES sharing mechanism is proposed incorporating capacity, energy and information. • An improved energy hub model is developed to provide guidance for MESs planning. • A new bi-level configuration strategy is proposed based on multi-dimension sharing. • A decomposition method combined with SADMM is implemented for model solving. [ABSTRACT FROM AUTHOR]

Reverse solute flux (RSF) is a key issue for operating forward osmosis (FO) systems and can cause the loss of draw solute (DS) and salt accumulation in the feed. Herein, an electrolysis-assisted FO (e-FO) system was developed for simultaneous RSF reduction and recovery of the reverse-fluxed DS. Applying a voltage of 1.5 V led to RSF of 3.34 ± 0.01 mmol m−2 h−1 (0.47 g m−2 h−1) in the e-FO system, 67.5 ± 0.5% lower than that of the control system; in addition, the e-FO system recovered ~0.32 g L−1 of the reverse-fluxed DS and this could not be realized in the control. When the e-FO system was examined with three types of the mimicked fertilizer, RSF reduction and DS recovery were largely affected by the individual components of a fertilizer DS. The energy consumption of the e-FO system was reduced by ~90%, from 0.38 ± 0.01 to 0.04 ± 0.01 kWh m−3 when the recirculation rate decreased from 60 to 15 mL min−1. Those results have demonstrated the technical feasibility of an e-FO system that is capable of reducing RSF and recovering the lost DS and will encourage further investigation by addressing several identified challenges. [Display omitted] • Weak electrolysis can reduce reverse solute flux by 67% in electrolysis-assisted FO. • Ion exchange membrane allows 68% of reverse-fluxed draw solute to be recovered. • The e-FO system could effectively reduce RSF and recover the mimicked fertilizer DS. • Energy consumption of e-FO is decreased by 90% via reducing liquid recirculation. [ABSTRACT FROM AUTHOR]

Nowadays, the integrated energy system (IES) has become a hot topic in the field of energy research. In this paper, a bi-level optimal configuration strategy is proposed for a community integrated energy system (CIES), which is based on energy supply-demand responses and robustness adjustable scenarios. First, from the perspective of energy supply and demand, various energy equipment on the community side and aggregated energy loads on the user side are analysed and qualitatively modeled, and a multi energy supply-demand of CIES is established. Next, according to the robustness requirements of IES planning, the scenario sampling, sorting, screening and reduction are performed subsequently to obtain a typical set of robustness adjustable scenarios. On this basis, a bi-level optimal configuration model that coordinates the aggregated configuration and operation is developed to design the CIES. While the upper-level model takes the lowest total annual cost as the goal to configure the quantity and capacity of energy equipment, the lower-level model optimizes the scheduling scheme with the aim of the best operation economy under typical scenarios. Finally, case studies are carried out based on a practical town area, and simulation results show the effectiveness and advantage of the proposed strategy. • A new energy supply-demand response model is developed. • A typical set of robustness adjustable scenarios is obtained for configuration. • A new bi-level optimal configuration strategy is proposed with coordinated planning and operation. • The economy, robustness, environmental protection and user interests are jointly considered. [ABSTRACT FROM AUTHOR]

Organic photovoltaic cells (OPVs) have attracted more and more attention due to its highly potential application to solve the energy crisis considering its advantages, such as low cost and ease of large area production. The power conversion efficiency (PCE) of OPVs has undergone a more than nine-fold increase from ∼1.0% by Tang in 1986 to 9.2% in 2010 announced by Mitsubishi Chemical. The major challenges of obtaining high efficiency OPVs are the synthesis of new narrow band gap materials, controlling molecular arrangement, designing novel configuration cells for better photon harvesting in the active layer. In the article, we summarized the recent progress of novel narrow band gap photovoltaic materials and the effective methods to control the morphology of donor and acceptor in the blend films for high performance of OPVs. [ABSTRACT FROM AUTHOR]

Integrated energy system (IES) is considered an effective way to alleviate energy supply pressure and improve energy efficiency, which has attracted considerable attentions worldwide. However, in existing studies, the coordination of uncertainty addressing and demand responses over different scheduling stages have not been fully considered in IES operation. Based on these considerations, a two-stage optimal operation method considering multiple uncertainties and integrated demand response is proposed for a community integrated energy system (CIES). First, given the CIES structure, various energy equipment are modeled and analyzed from the perspective of energy conversion and storage. Moreover, a generic optimal operation framework and model that comprises day-ahead and intraday stages is developed for a two-stage CIES scheduling. While the day-ahead stage introduces the time-shifted demand response (DR) to establish a robust optimization operation model, the intraday stage performs a stochastic scheduling with the adoption of replaced DR. Finally, a case study is carried out to demonstrate the operation model, and simulation results show that the proposed method can give play to the complementary advantages of multi energy sources and effectively promote the energy supply and demand balance in the presence of multiple uncertainties and demand responses. • Coordinately considered multiple uncertainties and IDR measures in CIES operation. • Proposed a two-stage optimal operation method for day-ahead and intraday scheduling. • Performed a case study to verify the effectiveness and advantages of this method. [ABSTRACT FROM AUTHOR]

As a typical hard and brittle material, optical glass is an important part of various optical systems and is widely used in space probes, aerospace technology, and other fields. Due to the unique material properties, the optical glass is prone to form defects such as micro-cracks and sub-surface damage during processing, which adversely affect the surface quality and performance of the workpiece. Ultrasonic vibration-assisted polishing (UVAP) technology is one of the methods to achieve high-quality processing of hard and brittle materials such as optical glass. However, UVAP technology usually suffers from long processing cycles and high energy consumption, which is not consistent with the development concept of the low-carbon economy. In this study, a unified evaluating mechanism for the experimental results was established using the entropy weight method (EWM) from the perspective of green polishing. The UVAP process parameters were optimized for obtaining excellent polishing quality and satisfactory processing energy consumption. The experimental results showed that the maximum reduction rate of energy consumption was 80%. Meanwhile, the improvement rates of surface roughness S a and S q were more than 40%. • A process optimization method with low energy consumption was constructed based on the concept of green polishing. • Six processing factors were considered including machining energy consumption. • A unified evaluating system of experimental results was established by using entropy weight method. [ABSTRACT FROM AUTHOR]

• Energy supply and demand balance equation considering energy cascade utilization is established. • DRL – based strategy can cope with uncertainties of renewable energy and energy demand within DD-PIES. • SAC embedded with domain knowledge rules is introduced to speed up network convergence. In order to improve the energy efficiency of park integrated energy system, this work proposes a model-free optimal operation strategy of diversified demands-park integrated energy system considering energy cascade utilization. First, by considering diversified demands of various users for energy, an energy cascade utilization mode and its corresponding multi-dimensional energy supply and demand balance equation is developed. Moreover, in view of the above structure, a model-free DD-PIES optimal operation strategy is further proposed. Among them, the model-free approach is realized on the basis of the interaction between agent and environment, combined with sufficient exploration and consequences learning of its behavior through experience. Compared to the previous works, this proposed strategy has good self-learning ability for multiple uncertainties of renewable energy and energy demand, and cuts down on inefficient exploration during the training process, while guarantee the security during the execution of actions by the agent. Finally, the rationality and validity of the proposed strategy in reducing operating cost and improving energy efficiency of the system are verified by a case study. [ABSTRACT FROM AUTHOR]

Abstract: This paper reports condensation heat transfer in a horizontal tube with a 14.81 mm inside diameter and a 1200 mm heat transfer length, by using the phase separation concept. The hollow mesh cylinder was formed by packaging two layers of mesh screen surface. The outer layer had the pore size of 76 μm. This invention constructs a multiscale condenser tube. The modulation of stratified flow and annular flow was focused on. Liquid was held within the mesh cylinder to increase the vapor covered tube wall surface to enhance the heat transfer for stratified flows. For annular flows, liquid droplets in the vapor core were captured by the mesh screen surface to increase the vapor void fractions near the tube wall, enhancing the hat transfer. The measurements showed that the heat transfer coefficients could be more than two times of those in the bare tube. The total thermal resistance was decreased by 45.6%, maximally. The heat transfer enhancement ratios were increased with the vapor mass fluxes, Gx in, for the condensation flow along the whole tube length. A pressure analysis explained the increased heat transfer trend. The increment of heat transfer enhancement ratios was suppressed with a liquid flow part in the tube. [Copyright &y& Elsevier]

An intraday, multi-objective, hierarchical and coordinated operation scheduling method for a multi-energy system (MES), which uses 15-min and 5-min scheduling intervals for different energy subsystems, is proposed. According to the characteristics of MES and the response time of energy conversion equipment, energy subsystems are dispatched on different dispatch intervals instead of unified dispatch intervals to dispatch energy subsystems. In a case study, the prediction error rate for a load is 5% and 2% when the dispatch interval is 15 min and 5 min, respectively; the prediction error rates for wind and solar energy output are 10% and 5%, respectively. Dispatching different subsystems with different intervals according to their characteristics reduces the impact of source and load uncertainties, which improves energy management. Multi-energy power dispatch considers exergy efficiency and the operation cost to improve the utilization energy efficiency. The Tchebycheff method, which considers the fuzzy entropy weight, is employed to balance the objectives between highest exergy efficiency and lowest operation cost. Numerical studies demonstrate that the operation cost of a multi-objective system is ¥500.8877 higher than that of a system with the objective of lowest operation cost. The exergy efficiency is increased by 3.94%, and the operation cost, which is reduced by ¥1706.9606, is 2.13% lower than that for the objective of highest exergy efficiency. Thus, the proposed method can balance the objectives between highest exergy efficiency and lowest operation cost. These findings provide a multi-dimensional dispatch scheme for dispatchers and highlight the development potential of an MES. • An intraday two-stage multi-objective dispatch method for a MES is proposed. • The power are scheduled considering varied response times of MES. • Two objectives of highest exergy efficiency and lowest operation cost are considered. [ABSTRACT FROM AUTHOR]