Steam ejector is widely used in the chemical industry, electric power, refrigeration and other fields. However, the ejector performance is usually poor, and the deviation far from the design performance limits its application range. During the actual installation and operation process, the primary nozzle of the ejector will deviate from the axis due to assembly error and vibration, which will affect the ejector performance. In this research, the ejector with a deviation of the primary nozzle is numerically simulated, and the variation law of ejector performance under different displacement and the inclination angle is obtained. It is found that the deviation of the primary nozzle will deteriorate the ejector performance. At the critical mode, large displacement will significantly reduce the entrainment ratio. When the displacement is 26.32%, the entrainment ratio will decrease by 18.0%. However, small displacement has no effect on the entrainment ratio. At the sub-critical mode, the deterioration impact of the primary nozzle inclination on the ejector performance is higher than that of the primary nozzle displacement. At the same time, the deviation of the primary nozzle reduces the critical back pressure, and the small displacement and inclination angle reduces the critical back pressure by up to 8.9% and 20.0%.
High-content atomically distributed W(V,VI) coordinated with O atoms as WO2 moieties anchored on the FeCo layered double hydroxide (FeCo LDH) nanosheets in the structure of SAC W-FeCo LDH is obtained...
PM2.5 is a bad output of China’s improved industrialization and rapid economic development, which seriously threatens people’s health and greatly hinders the sustainable economic development. Studying the socio-economic driving factors of PM2.5 emissions is of great significance for reducing air pollution and realizing green development. Therefore, based on the simultaneous consideration of space technology differences and time technology progress, this paper constructs an index decomposition analysis-production-theoretical decomposition analysis decomposition model under the global meta-frontier-production theory. Then, we decompose the PM2.5 emission concentration of 30 provinces in China from 2005 to 2018 into nine driving factors and discuss the impact of different factors from the national, regional, and provincial levels. The results reveal that economic activity is still the main factor to promote the increase of PM2.5 emission, but its effect decreases, while the inhibitory effect of catch-up effect on PM2.5 concentration increases gradually. In addition, economic activities have the greatest impact on the East China, while the time catch-up effect has a more significant impact on the Central and Western China. Moreover, the influence of energy intensity effect, space technology catch-up effect, and time technology catch-up effect is gradually increasing, which have become important factors to inhibit the PM2.5 emission. Based on the above results, we put forward relevant policy suggestions.
One-pot catalytic conversion of raw woody biomass into valuable chemicals and fuels is a promising strategy for relieving energy depletion. Here, we proposed an efficient catalyst combining highly dispersed and ultrafine platinum nanoparticles on ceria doped with Cr, enabling nearly complete conversion, and obtaining value-added chemicals and bio-fuel with high energy density. The key part of our approach lies on the flexible utilization of a synergetic catalysis system consisting of a redox potential CeCrO2-x, balanced acid-base properties and strong metal-support interaction. Abundant oxygen vacancies and enhanced wettability have been achieved by properly doping of Cr. Under nitrogen atmosphere, the catalyst still shows excellent conversion performance, not only can hydrogen transfer be achieved by using the “borrowed” hydrogen, but also the Guerbet reaction can suppress the formation of intractable chars. Moreover, alcoholophilicity facilitates the dispersion of the catalyst particles in ethanol, leading to higher mass transfer efficiency. The catalyst can be separated facilely and reused three times without obvious deactivation.
In view of the fact that current wind farms are mostly multi-wind turbines and it is difficult to accurately control a single wind turbine because of its high dimension in the optimization solution process, the article proposes a reactive power and voltage coordinated control strategy suitable for doubly-fed wind farms. The strategy is mainly divided into three layers. The first is the group layer, which can obtain the reactive power compensation task of the entire group according to the current voltage and voltage indicators of the group collection station. The second is the field layer, in which according to the reactive power compensation tasks issued by the group layer, the reactive power tasks are allocated to each field area based on the tabu search algorithm or the equal margin method. The third is the equipment layer, which allocates equal margins in the area according to the reactive power compensation tasks assigned by the field layer. At the field layer, this article divides 66 wind turbines into five different field areas to solve the reactive power compensation distribution task according to the voltage sensitivity characteristics of the wind turbines on different feeders.
Floating offshore wind turbines (FOWTs) work in a complex natural environment. Under the coupling effect of wind and waves, the platform experiences a six-degree-of-freedom motion, which affects the performance of the wind turbine. In this paper, a computational fluid dynamic method is used to investigate the effect of platform pitch and surge motion coupled at the same frequency as well as at different frequencies with an initial phase difference on the aerodynamic characteristics of FOWTs. The results demonstrate that the platform pitch and surge motion coupling makes the wind turbine operation more unstable. The power and thrust fluctuations are the largest when the two motions are coupled in the same phase, which leads to a dramatic change in the aerodynamic performance of the wind turbine during operation, and can easily cause hazards such as blade fatigue damage. When the initial phase difference does not affect the coupling motion frequency, the effect on the instantaneous power is more significant than that on the instantaneous thrust. However, the effect on the average power and thrust values is weaker. When the initial phase difference leads to reverse coupling of the platform pitch and surge motions, the fluctuation of power and thrust is reduced, and the wind turbine operation is more stable and safer.
Recent progress in submerged liquid hydrogen (LH2) cryopump technology development offers improved hydrogen fueling performance at a reduced cost in medium- and heavy-duty (MDV and HDV) fuel cell vehicle refueling applications at 35 MPa pressure, compared to fueling via gas compression. In this paper, we evaluate the fueling cost associated with cryopump-based refueling stations for different MDV and HDV hydrogen demand profiles. We adapt the Heavy Duty Refueling Station Analysis Model (HDRSAM) tool to analyze the submerged cryopump case, and compare the estimated fuel dispensing costs of stations supplied with LH2 for fueling Class 4 delivery van (MDV), public transit bus (HDV), and Class 8 truck (HDV) fleets using cryopumps relative to station designs. A sensitivity analysis around upstream costs illustrates the trade-offs associated with H2 production from onsite electrolysis versus central LH2 production and delivery. Our results indicate that LH2 cryopump-based stations become more economically attractive as the total station capacity (kg dispensed per day) and hourly demand (vehicles per hour) increase. Depending on the use case, savings relative to next best options range from about 5% up to 44% in dispensed costs, with more favorable economics at larger stations with high utilization.
Reuse of the solid residue from coal fly ash alumina extraction (FAAE) by acid leaching is problematic. Conversion of this solid residue into aluminum-rich zeolite (13X) and silicon-rich zeolite (ZSM-5) was investigated in this research. The FAAE residue was activated by alkali roasting with Na2CO3 powder (110% mass fraction) at 890 °C for 60 min. Silicon and aluminum were mainly present as two mineral phases, Na2SiO3 and NaAlSiO4, respectively, in the product obtained after roasting. The roasted product was dissolved in water (liquid/solid ratio of 2) after 20 min at 100 °C. The water-leaching liquor was investigated for total conversion to aluminosilicate zeolites without external aluminum or silicon addition. Hydrothermal synthesis of aluminum-rich zeolite 13X was successful after fine tuning of the conditions, although the filtrate had an unusually high SiO2/Al2O3 molar ratio. Production of 13X consumed a large amount of aluminum, which increased the Si/Al ratio to a level suitable for synthesis of ZSM-5. The synthesis of ZSM-5 from the mother liquor of 13X was proved feasible. The FAAE residue was transformed into high-value zeolite products by nearly 100%. Additionally, the tail liquid of this process, mainly containing Na2CO3, was completely recycled. This process could be used to realize high-efficiency and high-value utilization of similar aluminosilicate solid wastes.
Aeolian sandy soil in mining areas exhibits intense evaporation and poor water retention capacity. This study was designed to find a suitable biochar application method to improve soil water infiltration and minimize soil water evaporation for aeolian sand soil. Using the indoor soil column method, we studied the effects of three application patterns (A (0–20 cm was a mixed sample of mixed-based biochar and soil), B (0–10 cm was a mixed sample of mixed-based biochar and soil and 10–20 cm was soil), and C (0–10 cm was soil and 10–20 cm was a mixed sample of mixed-based biochar and soil)), four application amounts (0% (control, CK), 1%, 2%, and 4% of mixed-based biochar in dry soil), and two particle sizes (0.05–0.25 mm (S1) and <0.05 mm (S2)) of mixed-based biochar on water infiltration and evaporation of aeolian sandy soil. We separately used five infiltration models (the Philip, Kostiakov, Horton, USDA-NRCS (United States Department of Agriculture-Natural Resources Conservation Service), and Kostiakov-Lewis models) to fit cumulative infiltration and time. Compared with CK, the application of mixed-based biochar significantly reduced cumulative soil water infiltration. Under application patterns A, B, and C, the higher the application amount and the finer the particle size were, the lower the migration speed of the wetting front. With the same application amount, cumulative soil water infiltration under application pattern A was the lowest. Taking infiltration for 10 min as an example, the reductions of cumulative soil water infiltration under the treatments of A2%(S2), A4%(S1), A4%(S2), A1%(S1), C2%(S1), and B1%(S1) were higher than 30%, which met the requirements of loess soil hydraulic parameters suitable for plant growth. The five infiltration models well fitted the effects of the treatments of application pattern C and S1 particle size (R2>0.980), but the R2 values of the Horton model exceeded 0.990 for all treatments (except for the treatment B2%(S2)). Compared with CK, all other treatments reduced cumulative soil water infiltration, except for B4%(S2). With the same application amount, cumulative soil water evaporation difference between application patterns A and B was small. Treatments of application pattern C and S1 particle size caused a larger reduction in cumulative soil water evaporation. The reductions in cumulative soil water evaporation under the treatments of C4%(S1), C4%(S2), C2%(S1), and C2%(S2) were over 15.00%. Therefore, applying 2% of mixed-based biochar with S1 particle size to the underlying layer (10–20 cm) could improve soil water infiltration while minimizing soil water evaporation. Moreover, application pattern was the main factor affecting soil water infiltration and evaporation. Further, there were interactions among the three influencing factors in the infiltration process (application amount×particle size with the most important interaction), while there were no interactions among them in the evaporation process. The results of this study could contribute to the rational application of mixed-based biochar in aeolian sandy soil and the resource utilization of urban and agricultural wastes in mining areas.
Growing interest in the development of a hydrogen economy means that CO oxidation is increasingly important for upgrading H2-rich fuel gas streams for fuel cells. CeO2-supported catalysts are the most promising candidates for the catalytic oxidation of CO because of their high activity. In the present work, DFT+U calculations were performed to investigate the stability and CO oxidation reactivity of Ptn (n = 1−4) clusters supported on CeO2(111) (Pt/CeO2) and Pt-doped CeO2(111) (Pt/(Pt−Ce)O2) surfaces. The Pt clusters showed similar nucleation behavior on both CeO2 and (Pt−Ce)O2 surfaces. Further, the formation of oxygen vacancies (Ov) was facilitated because of surface charge depletion caused by the dopant Pt. Our DFT results suggest that the interfacial OV plays an important role in the CO oxidation reaction cycle, and the calculated energy barrier for the CO oxidation reaction on the Pt/(Pt−Ce)O2 surface is approximately 0.43 eV lower than that on the surface of the undoped catalyst, suggesting enhanced CO oxidation reactivity. Therefore, the chemical modification of the CeO2 support via doping is an effective strategy for improving the catalytic performance of Pt/CeO2.
With the process of China’s economic transformation and structural adjustment, the trend of thermal power industry transfer is more and more obvious. Under the background of industrial transfer, the research of the influence of environmental regulation on technological innovation has become a vital issue that needs to be discussed urgently for the current high-quality economic development. Based on the thermal power industry data in 30 provinces of China from 2008 to 2017, this paper constructs a mediating effect model to examine the relationship among environmental regulation, industrial transfer, and technological innovation. The results reveal that: (1) there is a U-shaped relationship between environmental regulation and technological innovation; (2) the increase of environmental regulation intensity promotes the thermal power industry to move to areas with loose environmental regulation; (3) industrial transfers play a mediating role in the process of environmental regulation influencing technological innovation. Therefore, the government should formulate scientifically effective environmental regulation policies so that the thermal power industry can realize orderly transfer and realize technological innovation.
The characteristics of arsenic emission and distribution of a typical Chinese coal-fired power plant renovated with ultra-low emission technique have been studied. The results showed that arsenic concentration in coal was 5.72 mg/kg, and the arsenic emissions in fly ash, bottom ash, gypsum, flue gas, and wastewater were 489.12 g/h, 5.15 g/h, 1.14 g/h, 0.46 g/h, and 0.03 g/h, respectively, corresponding to the proportion of arsenic in fly ash, bottom ash, gypsum, flue gas, and wastewater of 98.63%, 1.04%, 0.23%, 0.09%, and 0.01%, respectively. About 87.61% of the gaseous arsenic was absorbed by catalysts used for selective catalytic reduction (SCR). Low-low temperature electrostatic precipitator (LLT-ESP) plays a key role in decreasing particulate arsenic. Wet flue gas desulfurization (WFGD) has positive effects on absorbing both gaseous and particulate arsenic. The removal efficiencies across the air pollution control devices follow the order of LLT-ESP > WFGD > SCR. The LLT-ESP can achieve a significant arsenic removal efficiency of 99.94%, resulting in quite low arsenic emission to the atmosphere. According to the calculated arsenic emission factor, the total emission amount of arsenic to the atmosphere from all Chinese coal-fired stations with ultra-low emission control technique in 2020 is estimated to be about 9.67–11.59 tons/year.
High temperature is a growing threat and impacts public health through different exposure mechanisms. Our study constructs a comprehensive exposure measurement based on temperature variability, duration, and effective influence range. We investigate human responses to high temperatures through self-rated health scores based on individual-level data from China Labor-force Dynamic Survey (CLDS). Results show that higher temperature and temperature variability significantly decrease self-rated health scores. Subjective health risk is most significantly related to the cumulative temperature in the previous two weeks. We also find that the exposure effects at night and on weekdays are more severe. Workers who experience greater exposure from commuting and work environments are negatively impacted by high temperatures. In addition, men, the elderly, middle and low education groups, rural residents are more likely to be impacted by high temperatures.
In continuation of our two-step process development for the conversion of ethane to aromatics, this work focuses on catalyst performance improvement for ethylene aromatization. The approach is to apply steaming dealumination method to tailor ZSM-5 acidity to optimize its catalytic performance. Our results indicate that applying steaming treatment for the base Ga-ZSM-5 catalyst at specified conditions could reduce the total acid amount from 0.46 to 0.15–0.25 mmol/g, with 46–67% acidity loss, accompanied with the decrease of the acid strength for the strong acid sites. As a result, the catalyst prepared in this way exhibited a step-change performance enhancement in terms of cycle lifetime, target product yield/capacity, byproduct, coke formation and so on. Through examining the reaction mechanism and acid strength requirements for individual steps involved in ethylene aromatization, we conclude that steps that require strong acid strength – such as cracking and aromatics alkylation (both leading to catalyst deactivation) are effectively suppressed due to the lower acid amount/strength obtained after steaming treatment. The findings and this zeolite acidity tailoring technique will provide insights and solutions for zeolite-based acidic catalyst design.
At present, insufficient works have provided insights into the application of adsorption to remove CO2 in flue gas below room temperatures under ambient pressure. In this work, the effects of temperature, CO2 partial pressure and moisture on dynamic adsorption characteristics for CO2 are conducted for various adsorbents. Based on our findings, lower the adsorbing temperature can drastically enhance the adsorption of carbon dioxide over molecular sieves and activated carbon. Among various adsorbents, 13X molecular sieve shows highest adsorption capacity. With a concentration of 10% CO2 in flue gas, the specific adsorption capacity of CO2 over 13X molecular sieve is 0.11, 2.54 and 5.38 mmol/g at 80 °C, 0 °C and − 80 °C, respectively. In addition, the partial pressure of CO2 also has a significant impact on the adsorption capacity. With the increment of the concentration of CO2 from 1% to 10% under 0 °C, the specific capacity of 13X molecular sieve increases from 1.212 mmol/g to 2.538 mmol/g. Water vapor in flue gas can not only reduce the specific adsorption capacity of CO2 due to competing adsorption, but also increase the heat penalty of molecular sieve regeneration due to the water adsorption. An overall analysis is conducted on the energy penalty of capture 1 ton CO2 at various adsorption temperatures between − 80 °C and 80 °C, considering both the heat penalty of molecular sieve regeneration as well as the energy penalty for cooling the adsorber. It is found that the lowest energy penalty is about 2.01 GJ/ton CO2 when the adsorption is conducted at 0 °C.
Carbon emission allowance (CEA) has become a scarce resource against global climate change. Hence, the CEA allocation scheme is critical to improving its utilization efficiency and balancing regional development. However, most of the existing literature mainly focused on the formulation of allocation schemes but ignored the examination of CEA misallocation, which may damage productivity and regional development. This study intends to conduct a comparative analysis of Chinese provincial CEA allocation schemes by 2030 from a perspective of resource misallocation. For this purpose, 15 provincial CEA allocation schemes by 2030 based on the indicator method are developed first. Then a CEA misallocation index deriving from the extended Gini coefficient is proposed to examine the CEA misallocation of proposed schemes. Finally, an empirical analysis of China's provincial CEA allocation by 2030 is conducted. The results indicate that provincial CEA misallocation indeed occurs under the proposed allocation schemes with the CEA misallocation index ranging from 0.209 to 0.311, and the scheme based upon the efficiency principle has a relatively minimum misallocation index at 0.209. Furthermore, CEA misallocation is related to the carbon intensity reduction rate, and the scheme based on the efficiency principle could further achieve optimal CEA allocation when the carbon intensity reduction rate decreases. We suggest relevant decision-makers focus on the efficiency principle when developing a provincial CEA allocation scheme as it has strength in avoiding CEA misallocation.
Long-haul heavy-duty freight sector has always been relying on diesel fuel and hard to decarbonize. Hydrogen fuel-cell trucks (HFCTs) can play a critical role in substituting the diesel trucks and achieving carbon neutrality in freight sector. However, the extremely high cost has impeded their penetration. This paper proposed that government could harness freight platform to promote HFCTs by issuing the platform licenses with strings attached that priority dispatch and commission discount have to be provided to HFCT drivers. To simulate the effects of the proposed policy instruments, an optimization model was developed and applied. The results validated the ability of both priority dispatch and commission discount to promote HFCTs’ penetration. And combining the two mechanisms together can at most decrease the need for subsidy by 79%. Then the environmental effects were evaluated and the obtained emissions abatement cost ranges from 584 to 3712 RMB/t, which significantly exceeds the current carbon price in China. Besides, sensitivity analyses of key parameters have been conducted. It is found that the effects on promoting HFCT penetration of increasing subsidy is marginal diminishing. Business model innovation as well as further cost reduction of trucks and hydrogen fuels through technology progress are still in need.
Institution pages aggregate content on ResearchGate related to an institution. The members listed on this page have self-identified as being affiliated with this institution. Publications listed on this page were identified by our algorithms as relating to this institution. This page was not created or approved by the institution. If you represent an institution and have questions about these pages or wish to report inaccurate content, you can contact us here.