Energy Utilization Rate Research Articles

Thermodynamic analysis of a CCHP system with hydrogen production process by methane reforming enhanced by solar-assisted chemical looping adsorption

Combined cooling, heating and power (CCHP) systems integrated with renewable energy can greatly alleviate the fossil energy crisis and greenhouse effect. This work proposes a novel CCHP system, which consists of a solar-assisted sorption enhanced chemical looping steam methane reforming (SE-CL-SMR) hydrogen generation subsystem, a solid oxide fuel cell-gas turbine (SOFC-GT) subsystem, a dual-effect Li-Br absorption chiller/heat pump (DAC/H) subsystem, and a domestic hot water (DHW) subsystem. The impacts of the reformer temperature, pressure, the ratios of steam to carbon, calcium oxide to carbon, and nickel oxide to calcium oxide on the system’s methane conversion rate, hydrogen yield, hydrogen purity, and CO2 capture efficiency are also explored. While ensuring the hydrogen production effect and considering the lowest energy consumption, the optimal reforming temperature, reforming pressure, ratios of S/C, CaO/CH4 and NiO/CaO of the CCHP system are 560 °C, 1 atm, 3, 1 and 0.5, respectively. The system’s energy and exergy analysis is performed under the optimized operating condition. In comparison with the data of reference, the findings demonstrate that the system’s overall power generation efficiency is 53.23 %, the total energy utilization rate is 74.32 %, and the exergy efficiency is 52.87 %.

Capacity optimization allocation method for off-grid RES-H2 microgrid system considering the load-follow-source mechanism

Based on the uncertainty of the output of renewable energy such as wind and photovoltaic (PV), a capacity optimization allocation method considering the load-follow-source mechanism is proposed to solve the shortages of traditional methods, which is low in utilization rate of energy and low in economy. Firstly, considering the fluctuations of renewable energy sources (RES) and the operating characteristics of the electrolyzer, this paper proposes a capacity optimization method for off-grid hydrogen(H2) production system of renewable energy sources considering the load-follow-source operation mechanism. Then, combined with this mechanism, a capacity optimization allocation model is established, the objectives contain minimizing the levelized cost of hydrogen (LCOH), minimizing the capacity of energy storage, and optimizing the efficiency of power supply. Finally, an adaptive non-dominated sorting differential evolution algorithm (ANSDE) with external archiving is proposed to solve the established model. The calculation results show that the load-follow-source mechanism is effective for improving the economy of the system, and the proposed algorithm is high in efficiency and good in convergence comparing with traditional algorithms.

Preparation and characteristic of palmitic acid/flower-shaped CuS composite phase change material for effective heat storage and photothermal conversion

Designing and synthesizing the excellent heat storage and photothermal integrated composite phase change materials (PCMs) is an effective strategy for solar energy utilization. This work focuses on two kinds of CuS (cuboidal and 3D flower-shaped) with different morphology were designed as substrates and photothermal materials, and PA/F–CuS and PA/C–CuS composite PCMs have been prepared by melt-blending and vacuum impregnation method. Through SEM and pore structure characterization as well as leakage testing, it is proved that 3D layered flower-shaped CuS not only exposes the large specific surface area and rich adsorption sites, but also 2D thin layers can perform multiple reflections to improve the utilization rate of solar energy. The flower-shaped CuS is more suitable for the supporting material. Noteworthy, the latent heat of PA/F–CuS can reach 226.3 J/g, and the thermal conductivity is 0.3447 W/(m·K). Furthermore, compared with pure PA, the photothermal property of PA/F–CuS increased by 49.22–84.59%, and the photothermal conversion efficiency can reach 70.3%. This work provides an innovative idea for the design and manufacture of composite PCMs related to medium and low temperature solar energy storage, and has broad application potential in the field of thermal energy storage such as solar energy utilization and building insulation materials.

Evaluation Model of Distributed Photovoltaic Utilization in Urban Built-Up Area

Photovoltaic (PV) power generation is emerging as a key aspect of the global shift towards a more sustainable energy mix. Nevertheless, existing assessment models predominantly concentrate on predicting the overall capacity of PV power generation, often neglecting temporal dynamics. Drawing upon the urban energy substitution rate, utilization rate, and power supply stability, this study has devised a comprehensive evaluation model for the utilization of distributed photovoltaic systems (SUS). This model integrates the quantification of spatio-temporal features inherent in urban settings and buildings. Using Hohhot city as a case study, this study conducted simulations to analyze how the installation of PV systems affects the electricity consumption patterns across different land plots within the urban core. The study additionally examines how urban planning influences the adoption of PV power, taking into account both the timing of PV power usage and the stage of PV technology development. The evaluation model surpasses the constraints of current urban PV assessments, which primarily emphasize enhancing power generation potential without adequately quantifying supply–demand dynamics or spatial and temporal variations. This breakthrough significantly improves the precision and reliability of assessing the efficiency of distributed PV systems. Its implications extend widely to subsequent comprehensive evaluations of urban PV applications.

Broadband and strong visible-light driven photocatalytic enhancement utilizing two-dimensional plasmonics of Au/Cu-modified SrTiO3 perovskite nanostructures

Addressing limited access to clean drinking water demands innovative solutions to energy and environmental crises. Photocatalysis offers promise without eliciting secondary pollution, yet traditional metal oxide semiconductor photocatalysts encounter impediments in solar energy utilization and charge carrier recombination rates. To overcome these limitations, we present for the first time, a novel design, fabrication, and characterization of two-dimensional plasmonic noble metal/perovskite nanostructure hybrids for photocatalysis, combining Au as the plasmonic material with Cu-modified SrTiO3 as the semiconductor, fabricated on elastomeric polydimethylsiloxane substrates. Integrating localized surface plasmon resonance and Schottky junction-related band-bending significantly extends optical absorption into the ultraviolet-visible-infrared bands and enhances the effective carrier lifetimes, ensuring state-of-the-art photocatalytic efficiency. Exceptional photocatalytic performance in a 5-ppm aqueous methylene blue solution can be attained with 72.69-wt% Cu incorporation in the perovskite oxide, reaching a visible light-mediated photodegradation efficiency of 26% - an astounding 62.5-% efficiency increase compared to previous experiments without Cu modification. This advancement underscores the synergistic potential of noble metals and photocatalytic semiconductors in managing water purification challenges.

Technoeconomic analysis of rooftop PV system in elevated metro station for cost-effective operation and clean electrification

Metro system constitutes an essential component of urban transportation infrastructure, simultaneously serving as a significant energy consumer and carbon emitter. Integration of rooftop PV systems in elevated stations can effectively mitigate carbon emissions and enhance the utilization rate of clean energy. Nevertheless, current research rarely explores the application and feasibility analysis of rooftop PV systems in elevated metro stations. To address this research gap, the study investigates potential of rooftop PV systems applied in the elevated stations, and optimizes the PV scale and battery capacity for achieving the maximum net present value. The results show that the optimized photovoltaic-battery (PVB) system can bring about a PV self-sufficiency (SS) of 0.54, in the baseline scenario. For the entire line, SS can achieve 0.26–0.59 with the integration of PVB systems. Furthermore, the impact of skylights on energy consumption for illumination and PV power generation is discussed, and the PV potential of skylights is investigated. The results show that PV skylights lead to an increase a rise in the SS of 8.6%–15.3%. This study contributes reference for the potential of PV systems on elevated stations and for cost-effective operation and clean electrification of the urban rail transit sector.

Evaluation of active leeward side air-blowing layout on the lateral aerodynamic performance of high-speed trains in crosswinds environment: Sustainable and safe operation strategy

The lateral aerodynamic forces experienced by high-speed trains operating in crosswind environments affect trains' operating safety significantly. This paper used the Improved Detached Eddy Simulation (IDDES) method based on the Shear Stress Transport (SST) k-ω turbulence model to explore the mitigating effect of air-blowing at the leeward side of the train on the train's lateral aerodynamic forces. Different air-blowing positions and speeds were considered. The results indicate that the best mitigating effect can be achieved when simultaneously blowing air at the head, middle, and tail cars; in addition, when blowing air at the speed of 0.3 times of the resultant velocity, the rolling moment of the three cars reduced by 7.71%, 7.25%, and 25.46% respectively. Finally, the assessment of the mitigation efficiency was displayed to discuss the trade-off of rolling moment reduction and energy utilization rate for air-blowing. The research gives an insight into increasing the stability and safety of trains in crosswind based on active control, which can improve the safe operation threshold of trains.

Process Engineering Analysis of Transport Options for Green Hydrogen and Green Hydrogen Derivatives

The transition of the German economy and energy system toward CO2 neutrality requires large quantities of climate‐friendly chemical energy carriers, such as green hydrogen, to be imported. The decision on the most favorable import routes must consider its energy efficiency To respect the remaining CO2 budget to achieve the 1.5° climate target, the implementation time and therefore additional evaluation criteria must be taken into account. In this article, as a first step, the energy utilization rate () for different hydrogen import options is evaluated. Starting off from hydrogen at 25 °C and 25 bar produced in the exporting country, liquid hydrogen, ammonia, liquid methane (Green LNG), methanol, and liquid organic hydrogen carrier are considered as chemical energy carries. Liquid hydrogen is in future the most efficient import option ( = 7%) when gaseous hydrogen is supplied in the importing country. When direct utilization of the H2 derivatives is considered, the ammonia import route has the highest energy utilization rate with 77%. If point sources for CO2 are considered, direct utilization of methanol ( = 83%) and Green LNG ( = 76%) are energetically favorable import options. Additional significant criteria for a technological assessment are maturity of technologies, available capacities, infrastructures, and production processes.

Optimal Configuration of Multi-Energy Storage in an Electric–Thermal–Hydrogen Integrated Energy System Considering Extreme Disaster Scenarios

Extreme disasters have become increasingly common in recent years and pose significant dangers to the integrated energy system’s secure and dependable energy supply. As a vital part of an integrated energy system, the energy storage system can help with emergency rescue and recovery during major disasters. In addition, it can improve energy utilization rates and regulate fluctuations in renewable energy under normal conditions. In this study, the sizing scheme of multi-energy storage equipment in the electric–thermal–hydrogen integrated energy system is optimized; economic optimization in the regular operating scenario and resilience enhancement in extreme disaster scenarios are also considered. A refined model of multi-energy storage is constructed, and a two-layer capacity configuration optimization model is proposed. This model is further enhanced by the integration of a Markov two-state fault transmission model, which simulates equipment defects and improves system resilience. The optimization process is solved using the tabu chaotic quantum particle swarm optimization (TCQPSO) algorithm to provide reliable and accurate optimization results. The results indicate that addressing severe disaster situations in a capacity configuration fully leverages the reserve energy function of energy storage and enhances system resilience while maintaining economic efficiency; furthermore, adjusting the load loss penalty coefficients offers a more targeted approach to the balancing of the system economy and resilience. Thus, new algorithmic choices and planning strategies for future research on enhancing the resilience of integrated energy systems under extreme disaster scenarios are provided.

Exploration and optimization on thermoelectric conversion of waste heat of blast furnace slag

The iron and steel industry involves processes that generate abundant waste heat resources. The energy utilization rate can be improved by using thermoelectric conversion technology to directly convert waste heat into electric energy through the Seebeck effect. In this study, a special waste heat recovery device, designed according to the production environment characteristics of blast furnace (BF) slag, is proposed. The heat transfer process between the BF slag and thermoelectric generator (TEG) is analyzed, and the heat source temperature field model is constructed. Based on the temperature distribution, the size of the TEG is determined. The heat transfer behavior of the thermoelectric module (TEM) is optimized using a non-contact heat collection mode and a water-cooling device, which improves the temperature gradient. A thermal conductive silicone grease is introduced as the thermal conductive layer to achieve uniform distribution of the hot end temperature and improve the heat transfer capacity of the collector plate. After design optimization, the temperature gradient of the TEM increased by 15.3 °C and 38 % on average. The experimental results show that a single TEM can generate about 3.084 J of electric energy. Using 70 kg of BF slag with an initial temperature of 600 °C, the TEG per unit installed area can generate about 1.23 kJ of electric energy in 1 h. This study provides an important foundation for research in thermoelectric conversion, utilization of BF slag waste heat and sustainable development of the iron and steel industry.

Experimental analysis of slewing energy recovery potential of large hydraulic excavator

Large hydraulic excavators, characterized by large inertia of slewing movement, frequent accelerating and braking, have ideal working conditions for energy recovery and reuse. This paper investigates the slewing energy-saving potential of large hydraulic excavators via experiments conducted under different working conditions. Firstly, the working principle and energy flow of the slewing system of the hydraulic excavator are analyzed, and the evaluation indexes for energy-saving potential are proposed. Additionally, a 50 ton slewing experimental prototype is established, and comparative experiments are conducted. The energy flow analysis demonstrates that the energy loss due to slewing overflow is the primary factor for the low energy utilization rate of the slewing system. Finally, the influence of engine speed, slewing angle, and load on the potential of slewing energy recovery are analyzed. The experiential results reveal that the energy-saving contribution rates of accelerating and braking range from 42% to 45.36% while the energy regeneration rate is 56% under the single-action condition. And the comprehensive contribution rate of accelerating and braking energy is about 9.2% under the compound-action working condition, which has a significant energy-saving potential.

Electromagnetic forming of AA1060 sheet based on mixed forces generated by a three-coil dual-power system

The electromagnetic force used in electromagnetic forming is mainly divided into attraction and repulsion. Dual-coil attractive electromagnetic forming can be used in the field of sheet pit repair. However, the magnetic field and eddy current generated by the two coils compete with each other, and the energy utilization rate is low. Therefore, a compensation coil is introduced, and an electromagnetic forming scheme of a three-coil dual-power sheet based on mixed force is proposed and verified by simulation. It is found that the three-coil mixed force can effectively improve the competition between the magnetic field and eddy current. The loading of the mixing force is not a simple superposition of attraction and repulsion, but the mutual promotion of the two. The forming displacement of the three-coil mixed force forming scheme is 582% higher than that of the dual-coil attraction forming scheme, and 89% higher than that of the attract first and then repel forming scheme. The forming effect of the three-coil mixing force is related to the number of turns of the compensation coil. The research results can improve the energy utilization rate of electromagnetic forming and provide a new idea for the loading scheme of electromagnetic forming force field.

An auxiliary optimization method for electric heating renovation based on using a clustering algorithm

The large amount of pollutants emitted by coal heating in winter is one of the main causes of haze, which brings great trouble to people’s lives. To reduce air pollution caused by coal burning and improve air quality, the state advocates the transformation of traditional electric heating methods to accelerate the transformation of China’s energy system to a clean and low-carbon model and improve the utilization rate of renewable energy in China. Therefore, this article through the calculation of the residual capacity of the retrofit and the calculation of the air conditioning load to assist the electric heating transformation. Firstly, the average power of the transformer during a high power period is calculated instead of taking the maximum power directly, which solves the problem of small residual capacity caused by a large maximum load rate and maximizes the transformable capacity. Secondly, the cluster analysis of air conditioning heating as one of the typical electric heating methods is carried out by the K-means clustering method, and the air conditioning load is obtained as the data reference during the electric heating transformation to assist the optimization transformation of electric heating. The two methods are further studied and verified by two examples, and the theory guides the practice to assist the electric heating transformation and achieve the goal of energy saving and emission reduction.

Research on the optimization of the temperature field distribution of a multi-source microwave agent system based on event-triggered

Aiming at the problem of optimizing temperature distribution and heating efficiency in a multi-source microwave agent system, a collaborative tracking strategy using an event-triggering approach is explored. Firstly, setting the control object as a switch to optimize the system control process, a new cooperative switching strategy of event-triggered is designed to intensify the process of energy distribution by changing the time–frequency distribution of power. Secondly, exploring multi-agent architecture with an event-triggered multi-microwave source system to minimize communication frequency and energy consumption for faster agreement. Then, The material grouping strategy divides all materials into four categories based on their characteristics. Two materials, potato (group (a)) and SiC (group (c)) are selected for experimentation. Finally, a simple and easy-to-implement multi-source microwave numerical heating model was constructed using finite element analysis. The heating law described in this article was tested through experiments. The results showed that using this method increased the utilization rate of microwave energy in SiC by a maximum of 9.67% compared to traditional heating methods. Furthermore, it improved the temperature uniformity while maintaining excellent quality. Additionally, the energy utilization efficiency of potatoes was maximized by 8.76%, and the temperature uniformity was improved mostly by 12.04%.

Active power smoothing control strategy of offshore wind power system based on reduced matrix converter

On account of the fluctuation and randomness of wind speed, the output power of wind turbines fluctuates greatly, which may cause the frequency change of the power grid and increase the difficulty of power system dispatching. To solve this problem, an active power smoothing control (APSC) strategy based on RMC for offshore wind power systems is proposed in this paper. Compared with existing wind power converter systems, RMC adopted in this paper has the advantages of compact structure, small volume and high conversion efficiency. Based on the analysis of the exponential moving average (EMA) algorithm, a method for determining active power based on the fuzzy EMA algorithm is proposed. The method adjusts the cycle number N in real-time according to the wind speed, taking into account both the wind energy utilization rate and the smoothing performance of active power. The control principle of offshore wind power generation system (WPGS) based on RMC is analyzed in detail and the coordinated control strategy of RMC and inverter is proposed. Simulation results demonstrate the validity of the proposed method and control strategy.

Size effect of femtosecond laser helical drilling on nickel-based single crystal superalloy

Femtosecond laser has gradually become a reliable tool for processing high-quality film cooling holes (FCHs) of turbine blades in recent years. However, in the case of turbine blades with a variety of aperture drilling requirements, the influence of aperture on drilling quality and its internal causes are ignored. In this paper, the “size effect” of different aperture holes prepared by femtosecond laser helical drilling method was analyzed and compared in terms of geometric features, machining efficiency, hole wall ablation and drilling evolution process, and the formation mechanism of the “size effect” were revealed from the aspects of removal efficiency, laser spot overlap rate, energy shielding effect and residues discharge capacity. The results show that with the increase of laser scanning diameter D, the taper of the hole increases, the drilling efficiency increases first and then decreases, and the surface of hole wall is transformed from microvoids, microcracks and adhesive oxide residues into a regular nanostripes. The increase of D makes the radial spot overlap rate Pr decrease significantly, and Pr seriously affects the removal efficiency and thermal effect on the hole wall, which should be adjusted according to different apertures. Thermal accumulation and laser energy utilization rate attenuation caused by the energy shielding effect are the most important factors that deteriorate the processing quality and reduce the processing efficiency during femtosecond helical drilling. Therefore, for smaller aperture drilling, the strategy of process adjustment is to increase residues discharge capacity.

Optimizing air conditioning loads scheduling: A bi‐objective dynamic optimization algorithm considering life loss impact

AbstractAir conditioning loads (ACLs) can actively contribute to optimizing energy usage and increasing renewable energy utilization rate through scheduling. Existing studies on the participation of ACLs in DR have mainly focused on developing ON/OFF strategies, little consideration has been given to the impact of DR on the life loss of ACLs. In light of this, the present study first introduces an equation for quantifying the life loss of ACLs. Building upon this, an optimizing ACLs scheduling model is established considering life loss impact. As the relationship between life loss and refrigeration power is a complex non‐linear high‐order fractional function, it cannot be solved by conventional commercial solvers. Therefore, a bi‐objective dynamic optimization algorithm is proposed based on non‐linear fractional programming (NFP) to address this problem. To assess the effectiveness of our algorithm, it is used in a microgrid case with three schemes. Scheme 3 is aquatinted to consider the economic cost and the life loss of ACLs simultaneously, aiming to maximize the comprehensive benefit of the scheduling scheme. The results confirm the efficiency and superiority of the proposed algorithm.

Dynamic Brazilian tests of yellow sandstone under coupled static and dynamic loads

Through a series of static mechanical tests and (SHPB) dynamic impact tests, the static and dynamic mechanical parameters of rock as represented by yellow sandstone are determined, and the Holmquist-Johnson-Cook model parameters of the rock are calibrated using the test data and theoretical calculations. The feasibility of a numerical model is verified, and numerical analysis of the SHPB impact process under different radial pressure pre-loading is carried out on the basis of good verification. The results show that with increasing impact load, the degree of rock breakage increases, as does the dynamic tensile strength. With the application of increasing pre-static pressure, the dynamic tensile strength of the rock decreases gradually, and the maximum radial cumulative strain increases continuously under a given impact pressure, indicating that micro-cracks in the rock develop initially and then expand under the influence of pre-static pressure; the rock is more easily broken, and its weakening degree increases. Under coupled dynamic and static loading, the energy utilization rate of rock in the Brazilian splitting process is jointly affected by axial compression ratio and impact load. Too large a pressure ratio will reduce the strain-rate sensitivity of rock, resulting in low energy utilization rate, while too low an axial compression ratio will make the dynamic tensile strength of rock relatively high, which is not conducive to tensile failure. Therefore, on the premise of clear fracture form requirements, a suitable combination of axial compression ratio and impact velocity can improve the rock crushing effect and energy utilization rate.

Oxidation behavior and resultant deposition efficiency and material properties of laser aided additively manufactured stainless steel 316 L

Oxidation is a common issue in directed energy deposition (DED) based additive manufacturing (AM) processes. Severe oxidation is usually considered to be detrimental, which should be avoided. However, it is found that the surface oxidation of the deposited materials can also lower the laser reflectance, thereby increasing the utilization rate of laser energy and improving deposition efficiency. In this study, stainless steel 316 L (SS 316 L) was deposited using laser aided additive manufacturing (LAAM) process in the localized argon gas shielding environment and controlled argon environment, respectively, to investigate the evolution of oxidation on the surface and in the deposited material, as well as the effect of oxidation on the deposition efficiency and material properties. Results showed that severe surface oxidation of the materials deposited in the localized argon gas shielding environment effectively lowered the laser reflectance (14.5 %), which is much lower than that deposited in argon environment (71 %). Subsequently, with the same process parameters, the deposition efficiency in the localized argon gas shielding environment can be 1.57 times of that obtained in the controlled argon environment. Meanwhile, compared with the tensile properties of SS 316 L deposited in the controlled argon environment (YS 560 MPa, UTS 717 MPa, elongation 64 %), the tensile properties of SS 316 L deposited in the localized argon gas shielding environment (YS 456 MPa, UTS 631 MPa and elongation 57 %) are lower，whereas still show a good combination of strength and ductility.

Stability analysis of pumped storage hydropower plant in abandoned open-pit mine affected by dynamic surface subsidence of combined mining.

The construction of a pumped storage hydropower plant (PSHP) in an abandoned open-pit mine is a potential alternative to green mining and energy storage, which can increase the utilization rate of renewable energy and develop residual resources of abandoned mines. Dynamic surface subsidence affected by combined underground and open-pit mining (CUOPM) seriously affects the construction and operation of the PSHP and is one of the critical scientific issues that needs to be solved immediately. The stability of the PSHP was analyzed and treatment scheme of the goafs was proposed based on on-site measurement, theoretical analysis, and numerical simulation. First, the distribution of goafs in the Haizhou open-pit mining area was investigated and surface subsidence value was obtained using InSAR technology and ground monitoring. Secondly, the surface subsidence mechanism affected by CUOPM is analyzed and indicates the subsidence maximum values and scope of influence are greater than those of single underground mining. A dynamic surface subsidence prediction model for combined mining is established based on the Knothe time function model. Thirdly, based on the CVISC model, the numerical calculation models were established by using FLAC3D, and the characteristics and laws of surface subsidence in different periods of CUOPM were studied. The comparative analysis of the observation results shows that the proposed model and numerical simulation calculation method have excellent applicability and accuracy. Finally, a stability evaluation method of PSHP was established, and the results of the evaluation show that the affected areas are the semi-ground powerhouse (SGPH) and the west side of the lower reservoir. The method of grouting filling was used to treat the goafs, and the results showed that it effectively alleviates the dynamic surface subsidence affected by CUOPM, and provides a safety guarantee for PSHP.