• Energy Research
• Closed Access close
• Open Source close
• CN close
• CA close
• BE close
• UA close

Abstract The variation of properties with temperature have many practical applications in the area of chemical engineering and metallurgy, in the process of extrusion, the materials moving between a feed roll and on carrier belt. Here our intention is to explore the consequences of temperature dependent viscosity and variable thermal conductivity on flow of nanoliquid in a rotating system. Fluid between parallel plates is taken. Energy expression incorporates the exponential heat source. This analysis also explores the attributes of modified Arrhenius energy function with chemical reaction. Boundary layer problems have been computed via NDSolve approach. The obtained solutions are sketched for various estimations of embedded variables of interest. Results pointed out that both axial and transverse velocities show decaying behavior for higher rotation parameter. Thermal field boosts up with an enhancement of thermophoretic and space dependent heat source variables. Moreover the rate of mass transport decays through dimensionless activation energy.

Abstract The Liquefied natural gas (LNG) cryogenic submerged pump, the core power equipment for the transportation of liquefied natural gas, is prone to cavitation. However, based on the traditional analysis of the pressure drop, the irreversible loss after cavitation can barely be displayed quantitatively. To solve this problem, an entropy production diagnostic model (EPDM) by the contribution of viscous entropy production (VEP), turbulent entropy production (TEP) and wall entropy production (WEP) for the cavitation flow was established to calculate the energy loss. The cryogenic cavitation model and proposed EPDM were proved to be reliable after comparing results with Hord’s experiment in an ogive and cavitation experiment in a centrifugal pump. Then, by studying the total entropy production, it was found that the EPDM could well predict the occurrence of the critical cavitation and the deterioration of cavitation. When compared with TEP and WEP, the effect of VEP is negligible. As the cavitation area expands from the suction surface of inducer (id) to the first-stage impeller (impA), the cavitation process can be divided into three stages and the total energy loss increases significantly from the first stage to the third one. Through the global distribution of energy loss, it was found that the faster growth of the loss in the second-stage impeller (impB) and the second-stage guide vane (gvB), not in id and impA, contributes more to the energy loss after cavitation. Finally, from the variation of ratio of TEP to WEP, it reveals that cavitation has a greater effect on the WEP rate for the impB, but the turbulent viscous dissipation is still dominant, while the eddy dissipation and resistance loss in gvB with the evolution of cavitation are both crucial.

Abstract With the ever-growing need for lithium-ion batteries, particularly from the electric transportation industry, a large amount of lithium-ion batteries is bound to retire in the near future, thereby leading to serious disposal problems and detrimental impacts on environment and energy conservation. Currently, commercial lithium-ion batteries are composed of transition metal oxides or phosphates, aluminum, copper, graphite, organic electrolytes with harmful lithium salts, polymer separators, and plastic or metallic cases. The lack of proper disposal of spent lithium-ion batteries probably results in grave consequences, such as environmental pollution and waste of resources. Thus, recycling of spent lithium-ion batteries starts to receive attentions in recent years. However, owing to the pursuit of lithium-ion batteries with higher energy density, higher safety and more affordable price, the materials used in lithium-ion batteries are of a wide diversity and ever-evolving, consequently bringing difficulties to the recycling of spent lithium-ion batteries. To address this issue, both technological innovations and the participation of governments are required. This article provides a review of recent advances in recycling technologies of spent lithium-ion batteries, including the development of recycling processes, the products obtained from recycling, and the effects of recycling on environmental burdens. In addition, the remaining challenges and future perspectives are also highlighted.

AbstractAu@Pd core–shell nanobricks (CNBs) with concave surfaces and Pd shells with a thickness of approximately 5 nm were synthesized by co‐reduction of HAuCl4 and H2PdCl4 in the presence of Au seeds and Ag ions. These as‐synthesized concave CNBs exhibit significantly enhanced catalytic activity for the electrooxidation of ethanol in alkaline media compared to the commercially‐used Pd black. The improved performance of the Au@Pd CNBs can be attributed to the exposed stepped surfaces, high‐index facets, and the synergistic effects of the core and shell metals.

Abstract In view of the current energy demand for miniaturized equipment in extreme environmental fields, such as in deep space exploration. A new fan-shaped radioisotope thermoelectric generator is innovatively presented and designed. Thin-film thermoelectric materials used for miniaturized radioisotope thermoelectric generators are first prepared by electrochemical methods. The prepared fan-shaped radioisotope thermoelectric generator has a volume of 5.75 cm3 and consists of 8 thermoelectric modules and 32 thermoelectric legs. The study finds that when a 1.5 W heat source is loaded, the temperature difference of the device is 54.8 K, the output voltage and the maximum output power is 174.88 mV and 333.20 nW, respectively. On this basis, the number and size of the modules are optimized by the finite element method. When the thermoelectric leg size is optimized to 9 × 2 mm2 and the number of modules is 8, the maximum output power can be up to 369.02 nW. The corresponding experimental verification work is further developed and discussed. This work provides a novel solution for the energy supply problem of small-volume devices in extreme space environments.

Abstract Domestic wind turbine manufacturing sector in China has experienced development stages starting from scratch to mass production. During the 11th FYP period (2006–2010), the main goal of wind power policy in China is to promote the commercialization of wind power by large-scale deployment of wind farms. This goal has been realized to a great extent and now the cost of wind power generation is nearly comparable to coal-fired power generation in China. The industry policy, which devotes to mass production of domestic wind turbines, is also largely successful. The purpose of the paper is to provide an overview on wind turbine manufacturing sector in China. The policy evolution in different stages, achievements and challenges pertinent to the sector are addressed in the paper. Key findings are that the misleading industry policy, which provides strong incentive to blind entrance and “competition for scale and price” and restrains innovation as well, is the key obstacle for the sustainable development of the sector. Deficient technology standard and qualification system and the misplaced franchise bidding system also indulge vicious competition and oversupply. Creating a level playground for all turbine supplies, providing strong incentive to innovative manufacturers, establishing thorough and practicable standard and qualification system, and fine-tuning the directive of the franchise bidding system towards technology and service are the primary policy implications proposed by our study.

Abstract The promise of redox flow batteries (RFBs) utilizing soluble redox couples, such as all vanadium ions as well as iron and chromium ions, is becoming increasingly recognized for large-scale energy storage of renewables such as wind and solar, owing to their unique advantages including scalability, intrinsic safety, and long cycle life. An ongoing question associated with these two RFBs is determining whether the vanadium redox flow battery (VRFB) or iron-chromium redox flow battery (ICRFB) is more suitable and competitive for large-scale energy storage. To address this concern, a comparative study has been conducted for the two types of battery based on their charge–discharge performance, cycle performance, and capital cost. It is found that: i) the two batteries have similar energy efficiencies at high current densities; ii) the ICRFB exhibits a higher capacity decay rate than does the VRFB; and iii) the ICRFB is much less expensive in capital costs when operated at high power densities or at large capacities.

AbstractTo determine the effect of different agents on the dynamic characteristics of floc structures, ferric chloride (FC) and anionic polyacrylamide (APAM) were dosed as coagulant and flocculant, respectively, to flocculate the coal slime water. Particle vision and measurement (PVM) was employed to monitor the flocculation process in situ. The results showed that the floc could grow to a size of approximately 1 mm only under conditions of 100 mg/L FC and 50 mg/L APAM. The coagulant dosage influenced either the aggregation of the slime particles or the conformation of the flocculant. If the coagulants were insufficient or excessive, the flocculant conformations were stretch chains and resembled unable to bridging the slime particles as shown in the captured images. The variation of the relative backscatter index (RBI) during the process indicated that the required residence time for flocculation was proportional to the ratio of particle size at the end of flocculation to that at the beginning of the process. It can be concluded that PVM is an effective instrument that can obtain useful dynamic information of the flocculation process by combining real‐time images and the RBI.Practitioner Points The coagulant concentration affects the conformation of the flocculant. The required retention time is depended on the max size that flocs can reach. PVM is a powerful instrument for studying dynamic flocculation process in situ.

Abstract Residues from the liquefaction of Black Thunder subbituminous and Illinois No. 6 bituminous coals in an autoclave and a bench unit were examined petrographically. Optical microscopy proved valuable for ranking the samples on the basis of overall coal conversion and presence of vitroplast, granular residue and inertinite. It was observed that in the autoclave that runs on Black Thunder coal, K 2 CO 3 was a superior water gas shift reaction catalyst to NaAlO 2 , or a combination of CS 2 and Fe or Mo catalysts. The amount of vitroplast showing vacuoles and cenospheric morphology in the residues was inversely related to the CO conversion, indicating that the mechanism of vitroplast dissolution is linked to the availability of active CO intermediates (e.g. formate ion, HCOO − ). A CO-steam mixture was more effective than syngas or pure H 2 and N 2 in increasing Black Thunder coal conversion, and resulted in greater morphological changes to the coal particles. In contrast, for Illinois No. 6 coal pure H 2 had a greater effect on coal solubilization and overall conversion than pure CO at the same temperature; this was attributed to the absence of carboxylates to react with the formate ions. Higher mesophase and coke contents were detected in some bench unit runs on Black Thunder coal that were operated in counterflow mode. Higher severity, poorer mixing, longer residence time and a reduction in pressure by almost 3.5 MPa are believed to be responsible for the retrogressive reactions forming mesospheres in these cases.