Publications

Shadow is an important hurdle to the power generation efficiency of solar photovoltaic (PV) modules. So far, most previous studies on this aspect have focused on simulation, lacking full-scale experimental study, not to mention the relevant quantitative experimental analysis. Therefore, this study conducted a full-scale outdoor experimental and empirical study on the PV modules under different shadow conditions. Experimental results revealed that the power generation capacity of a single-string PV module decreases by approximately 90 % when a specific solar cell is entirely obstructed. When a cell is shadowed, the short-circuit current drops by 20–25 %. The open-circuit voltage (V oc ) drops by 25–30 % when 2/3 of the PV modules are shadowed. The short-circuit current (I sc ) has a linear relationship with a smaller shadow less than a solar cell, and the V oc has a linear relationship with a shadow larger than a solar cell. However, the power generation efficiency exhibits a nonlinear relationship with the shadow ratio of the cells when they are subjected to shading. Based on the full-scale experimental tests, this study developed an empirical model, for the first time, to address the relationship between shadow ratio and power generation efficiency, where the power generation efficiency is negatively related to the 3/2 power of the shadow area. The obtained research outcome, together with the empirical model, can pave the way for future large-scale (e.g., global scale) study on addressing the impact of shadow conditions (e.g., bird droppings, dark clouds, gravel, and dust) on the power generation of solar PV systems.

No abstract is provided for this article.

The ethylene and vinyl acetate (VA) mixture must be compressed to a high pressure of over 100 MPa in a hyper-compressor system to initiate the polymerization. This paper presents a numerical and experimental investigation into the effects of VA concentration on the performance of a hyper-compressor. To this end, an equation of state in the form of Helmholtz free energy was developed to calculate the real thermodynamic properties of VA–ethylene mixture. The average absolute deviations of density and compressibility factor for VA-ethylene compared with experimental values were 1.82% and 1.46%, respectively. Additionally, a three-dimensional (3D) computational fluid dynamics (CFD) model was constructed considering real-fluid thermodynamics, incorporating the motion of the central valve and upstream and downstream pressure pulsations. The predicted [Formula: see text] diagram and pressure pulsation were compared with experimental data to validate the accuracy of the 3D-CFD model. The results demonstrated that a higher VA weight fraction results in a shorter expansion and compression phase; higher indicated power, suction, and discharge losses; and greater pressure fluctuation. The increment of power loss during the discharge process accounted for 73.27% of the indicated power growth 35.96 kW as the VA weight fraction increased from 0% to 40%. The increment of pressure pulsation in the suction and discharge pipe were mainly attributed to high-frequency pulsations above 10 orders and low-frequency pulsations below 10 orders, respectively.

An analytical model was developed in this study to predict the heat transfer and ignition time of solids subjected to time-dependent thermal radiation (HF=at b ). Both surface and in-depth absorptions, corresponding to opaque and translucent materials, were considered in the model and critical temperature was employed. The predictions of the new model fit well with the experimental and numerical results. The results show that for surface absorption the ignition time to the power of −(b+0.5) is proportional to a, and the reciprocal of square root of ignition time is linearly correlated with ignition HF. Furthermore, a critical ignition HF was found to represent the lower limit of ignition HF range, which is different with the critical HF at constant HF. While for in-depth absorption, the ignition time to the power of −(b+1) and −1 were linearly proportional to a/(b+1) and ignition HF, respectively. For translucent solids, the analytical model cannot be applied to constant HF but can provide relatively high accuracy in predicting ignition time under variable HF. Also, the effect of in-depth absorption coefficient on ignition time were addressed, and it was found that this important parameter exerts its influence on ignition process following the similar mechanism with that of constant HF.

Na-ion batteries (NIBs) have attracted increasing attention given the fact that sodium is relatively more plentiful and affordable than lithium for sustainable and large-scale energy storage systems. However, the shortage of electrode materials with outstanding comprehensive properties has limited the practical implementations of NIBs. Among all the discovered anode materials, transition-metal sulfide has been proven as one of the most competitive and promising ones due to its excellent redox reversibility and relatively high theoretical capacity. In this study, double-morphology N-doped CoS2/multichannel carbon nanofibers composites (CoS2/MCNFs) are precisely designed, which overcome common issues such as the poor cycling life and inferior rate performance of CoS2 electrodes. The conductive 3D interconnected multichannel nanostructure of CoS2/MCNFs provides efficient buffer zones for the release of mechanical stresses from Na+ ions intercalation/deintercalation. The synergy of the diverse structural features enables a robust frame and a rapid electrochemical reaction in CoS2/MCNFs anode, resulting in an impressive long-term cycling life of 900 cycles with a capacity of 620 mAh g–1 at 1 A g–1 (86.4% theoretical capacity) and a surprisingly high-power output. The proposed design in this study provides a rational and novel thought for fabricating electrode materials.

As global warming worsens, countries around the world have developed policies to reduce carbon emissions and accelerate the transition to renewable energy. Recently, cement-based supercapacitors have attracted significant attention due to their low energy consumption and multifunctionality, offering a promising solution for large-scale energy storage in renewable energy systems. This review provides an overview of the advancements, mechanism and characterization of cement-based supercapacitors, followed by an analysis of performance studies on mechanical and electrochemical properties based on cement types, water to cement (W/C) ratio, curing age, additives, and various electrodes of contemporary interest. The progress in overcoming issues related to the energy storage capacity and mechanical properties of polymer modified cement-based electrolytes is analyzed. In addition, high-performance and long-lifespan electrodes modified by nanomaterials and metal oxides are essential for establishing highly efficient cement-based supercapacitors. The multifunctionality of these materials is further discussed, emphasizing mitigating intrinsic contradictions is key to large-scale production and commercialization. Finally, perspectives are provided on the future development requirements of advanced cement-based supercapacitors, focusing on sustainability, economic promotion, social impact, and industrial stability. This review not only provides direction for researchers in renewable energy storage but also offers valuable insights for achieving energy savings and carbon neutrality.

Solar chimney under heating modes is much more complicated than those under cooling mode as its performance should consider both airflow rate and temperature rise. Its heating performance and optimization designs are still unclear under various heating modes. This study then addressed the impacts of typical design factors on its heating performance numerically and empirically under three heating modes, including two fresh-air heating modes (i.e., through inlet and window) and a sealed heating mode. Similar to the cooling mode, the impacts of the analyzed design factors on the temperature rise and airflow rate can be expressed by the exponential function. Differently, the cavity gap under the three heating modes shows negative exponentials (-0.18 ∼ -0.088), while the cooling model is between 0.652 ∼ 0.756. Solar radiation shows positive exponential under both heating and cooling modes, and its impacts on airflow rate are relatively higher under cooling mode. Also, the temperature rises inside both the chimney cavity and the attached room along the height show natural exponential functions. A lower window (or even closing it and replacing it with a bottom vent near the floor for fresh air supply) is suggested for the two heating modes with fresh air supply to avoid vertical temperature differences inside the room. Compared to the fresh-air through inlet, sealed heating offers a 292.8% higher air temperature rise and 3.9% lower airflow rate; and fresh-air through window offers a 19.3% higher airflow rate and 44.5% higher air temperature rise. Therefore, the modes of fresh-air through inlet and window can be applied to those locations under cool and cold climates, respectively; and sealed heating is only applicable to those scenarios without or with limited occupants (i.e., storage) as no fresh air is supplied.

The structure analysis of extremely thin thermally grown SiO2 (< 25 Aå) indicates that most silicon atoms share two of the four tetrahedrally-coordinated oxygen atoms with the adjacent silicon atoms. Molecular mechanics simulation of the single chain of SiO2 tetrahedrons is presented. The extremely thin oxide film is composed of the close-packed short chains of the tetrahedrons perpendicular to Si substrate. Diffusion experiment of an acid vapor through non-oxide polyhydroxystyrene films de-convolutes four prototropic states of fluoresceinamine monolayer to resemble the change of the intermediate states of Si atoms during the thermal oxygen diffusion processes at Si/SiO2 interface.

With the rapid development of the electric vehicle industry, the issue of recycling retired power batteries is becoming increasingly prominent. Considering the adoption of blockchain technology to enhance information traceability for retired power batteries, we construct three closed-loop supply chain decision-making models: a supply chain that does not adopt blockchain technology, a manufacturing enterprise that independently bears the input cost of blockchain technology, and a scenario which both manufacturing and selling enterprises jointly bear the blockchain technology input costs. Through the comparative analysis of the equilibrium solutions of these models, including the profits of each supply chain member, consumer surplus, environmental impact, and social welfare, it is concluded that the level of information traceability increases with the increase of the blockchain technology input cost-sharing ratio λ by the selling enterprise. However, there is a threshold for λ and λ cannot be infinitely increased. The profits of both manufacturing and selling enterprises increase with the adoption of blockchain technology, yet the ladder-utilizing enterprise achieves the highest profits when not adopting blockchain technology. Furthermore, the adoption of blockchain technology can increase consumer surplus and social welfare while reducing the impact on the environment. These studies provide theoretical guidance on both economic and social environment for the operation decision of each member in the closed-loop supply chain of power batteries.

The shockwave and high-temperature flame of dust explosion in the dust collector are often transmitted through the dust removal pipeline, and then cause secondary harm. In this study, the dust explosion propagation in a typical dry dust collector connected with dust removal pipelines was studied by CFD. The impacts of static activation pressure of the pressure relief panels on the explosion propagation were also addressed. The dust explosion propagation in the dust removal pipeline showed multiple accelerated combustion processes and severe pressure shocks. The explosion pressure and temperature first increase and then decrease along with the pipeline. Under a higher static activation pressure, the maximum explosion pressure along with the pipeline increases by 144%, where the average velocity of the dust propagation, dust consumption, pressure shock wave, and flame propagation increase by 82.2%, 32.1%, 25.3%, and 70.1%, respectively. When the static activation pressure increases from 0.01 MPa by more than 25%, the changes of the dust explosion pressure and flame propagation in the pipeline are observed limited. The explosion-proof valve should be set between 5 m and 10 m in the dust removal pipeline. And the lower the static activation pressure, the closer the explosion-proof valve. This research provides a scientific basis for the effective control of dust explosion disasters in dust removal systems.

This paper presents a low-cost Built-In Self-Test (BIST) scheme, which is based on the principle of parity check code. The proposed circuit is consisted of a XOR network, a frequency decrease module, a BIST controller and a fault detector module. Different from the previous methods of PLL BIST, digital signals from the divide-by-N are grouped as transmission codes, and parity check codes are produced synchronously by the BIST controller. Then the results of parity checking are imported to the fault detector and final test results are generated. Purely digital design flow is adopted and hybrid faults models are used to evaluate the efficiency of the circuit. Experimental results indicates that the proposed method can provide the highest test coverage and lower area overhead, which are 98.3% and 4.2%, respectively.

Polyhedral carbon-coated structural N-CoS₂@C nanoparticles are synthesized by a facile one-pot solvothermal technique and exhibit excellent sodium ion storage performance.