Interfacial bond properties of six different epoxy resins used to coat submerged concrete structures were investigated. Test variables included coating type, coating equipment, and underwater curing ...time. Coating thickness and pull-off bond strength were measured using commercially available test equipment. Coating thickness and bond strength varied greatly depending on the manufacturer. The standard (control) coating equipment positively influenced the bond strength compared to other equipment. The effect of curing time on the bond properties was not significant within the range of 24 to 72 h. Lastly, some important considerations for the underwater coating of actual marine and coastal concrete structures were discussed, and suggestions for future research are presented.
British Standard 8110, Canadian Standards Association A23.3-04, and American Concrete Institute 318-11 suggest the equation to estimate the shear strength of reinforced lightweight concrete beam ...based on the 28-days compressive strength. However, the compressive strength of LWC can be variable depend on the type of lightweight aggregate selected and this can cause problems in the accurate prediction of shear strength. LWC generally showed the lower strength compared to that of conventional concrete due to the high internal porosity of lightweight aggregate. Understanding the effect of different aggregate type on the shear capacity of reinforced LWC beams is important to improve existing standards and better application of LWC in actual structures. Experimental studies were conducted to investigate the effect of aggregate type on the shear capacity of reinforced all lightweight concrete beams.
Total 12 RC beams with three different coarse aggregates were prepared and comparisons were made with existing design guidelines. In sum, some important suggestions were made for the better use of LWC in actual concrete structures. KCI Citation Count: 0
This study comprehensively investigates hydrogen production from green ammonia reforming, including synthesis of catalysts, reactor development, process integration, and techno-economic analysis. ...In-house developed Ru/La–Al2O3 pellet catalyst having perovskite structure showed high catalytic activity of 2827 h−1 at 450 °C and stability over 6700 h at 550 °C, exceeding the performance of the majority of powder catalysts reported in the literature. A scalable 12-faceted reactor adopting the as-produced catalyst was designed to enhance heat transfer, producing over 66 L min−1 of hydrogen with state-of-the-art ammonia reforming efficiency of 83.6 %. Near-zero CO2 emission of hydrogen extraction from green ammonia was demonstrated by-product gas recirculation as a combustion heat source. A techno-economic assessment was conducted for system scales from 10 kW to 10 MW, demonstrating the effect of reduced minimum hydrogen selling prices from 7.03 USD kg−1 at small modular scales to 3.98 USD kg−1 at larger industrial scales. Sensitivity analyses indicate that hydrogen selling prices may reduce even further (up to 50 %). The suggested hydrogen production route from green NH3 demonstrates superior CO2 reduction ranging from 78 % to 95 % in kg CO2 (kg H2)−1 compared to biomass gasification and steam methane reforming. These findings can be used as a basis for following economic and policy studies to further validate the effectiveness of the suggested system and process for H2 production from NH3.
•Experimental and techno-economic analyses of H2 from green NH3 are conducted.•As-developed Ru pellet catalysts showed high activity of 2827 h−1 at 450 °C.•Reforming efficiency of 83.6 % was achieved at 5 kWe scale with a COX free operation.•Minimum H2 selling price of 4 USD kg−1 is expected at industrial scales >10 MW.•CO2 emission can be reduced up to 95 %, compared to the conventional processes.
The purpose of this meta-analysis study is to examine the correlations between the Dimensions of Learning Organization Questionnaire (DLOQ) and frequently examined outcomes including organizational ...performance and employee attitudes. Positive relationships were found between the DLOQ and organizational performance (e.g., financial, knowledge, and innovative performance) and employee attitudes (e.g., organizational commitment and job satisfaction) and the sub-dimensions (e.g., affective, continuance, and normative commitment), with a notable exception of a negative relationship between the DLOQ and turnover. Because the DLOQ has been used in many countries over the years, this study also examined the influence of national culture on the outcomes. Power distance moderated the relationship between the learning organization and overall organizational performance. Our meta-analytic review makes substantive contributions to the literature on the learning organization concept and the study of national culture as a significant moderator. Implications of these findings and suggestions for future research are discussed.
The ultimate goal of this work is technical and economic feasibility analysis of a methane dry reforming (MDR) using a coke oven gas (COG) for a H2 production capability of 700 m3 h−1 because this ...technology is the promising alternative approach to H2 production as well as CO2 utilization. From process simulation works, process flow diagram is created for MDR using COG and validated by performance results from the previously reported literature. With a process flow diagram to be confirmed via model validation, the best reaction temperature of 1073 K is observed in terms of methane conversion. Based on process simulation results, economic analysis is performed. Furthermore, case studies focusing on an operating expense are conducted to consider various aspects of a CO2 price and confirm the effect of CO2 price on unit H2 production cost. Respective H2 production costs of 3.27, 2.71, and 2.38 $ kgH2−1 for a case 1 (reference), a case 2 (case 1 + CO2 absorption), and a case 3 (case 2 + CO2 from a blast furnace) are obtained. In addition, uncertainty analysis is performed to suggest the possible H2 production cost range for each case by considering the uncertainty of CO2 price fluctuation. Consequently, it is expected that a MDR using a COG is feasible for a H2 production as well as CO2 utilization technology compared to the current by-product H2 cost if carbon cap-and-trade system is activated.
•Techno-economic analysis of dry reforming using coke oven gas was conducted.•Case study with various CO2 utilization methods was performed.•Uncertainty analysis using a Monte-Carlo simulation method was carried out.•Technical and economic insights for dry reforming can be provided.
•A biorefining process is developed to produce butene oligomers from biomass.•1,5-pentanediol and high-purity lignin are coproduced to improve process economics.•Heat integration is performed to ...reduce energy requirements by 86.7%.•The minimum selling price of butene oligomers is calculated as $4.21/GGE.•Major cost drivers of the process are derived via sensitivity analysis.
In conventional biomass-to-biofuel production processes, cellulose and hemicellulose are converted only to biofuels. However, to improve the economics of the process, it is desirable that some fractions of biomass be produced as fuels and other fractions as chemicals. This coproduction of fuels and chemicals also enables a flexible response to the market conditions of bioproducts, rather than producing only biofuels or biochemicals. Moreover, the use of all fractions, not only cellulose and hemicellulose but also lignin, improves the economics of the process. We propose a biorefinery strategy for the coproduction of liquid hydrocarbon fuels and chemicals from lignocellulosic biomass. In this study, all three primary components of biomass were converted into high-value products that can be commercialized: (1) cellulose, which is converted into butene oligomers (BO) for transportation fuels, (2) hemicellulose, which is converted into 1,5-pentanediol (1,5-PDO) that can be used as polyester and polyurethane components, and (3) lignin, which is converted into carbon products, such as carbon fibers or battery anodes. By maximizing the biomass utilization up to 47.8% from biomass to valuable products, the economic viability of the proposed process can be increased. Technoeconomic analysis shows that the minimum selling price of BO is $4.21 per gallon of gasoline equivalent in the integrated strategy, indicating that it is a promising alternative to current biofuel production approaches.
Hydrogen has been considered as a clean energy carrier by generating electricity via fuel cells without carbon dioxide emissions; however, in the current stage, most hydrogen is produced by a steam ...methane reforming, emitting carbon dioxide as a byproduct, together. In this context, a green hydrogen production system, which is consisted of water electrolysis and a renewable energy plant, should be expanded to prepare for the upcoming hydrogen society in the future. A techno-economic analysis is carried out for green hydrogen production based on seasonal solar radiation data in the case of the single and the hybrid system, which is designed as only alkaline water electrolyzer and a combination of alkaline water electrolyzer and energy storage system. In addition, a carbon footprint analysis is performed to quantify the carbon dioxide emissions for the proposed systems. And the optimal scale of alkaline water electrolyzer and energy storage system is figured out via a genetic algorithm considering a carbon tax on emitted carbon dioxide. Based on itemized cost estimation results, 6.55 and 6.88 USD kgH2−1 of unit hydrogen production costs were obtained for the case of a hybrid and a single system, respectively. Further, the results present that the hybrid system is preferred when Li-ion battery costs decrease to under 79.67 USD kWh−1. In addition, the capital cost is a crucial factor to figure out the optimized alkaline water electrolyzer scale and energy storage system capacity that set the optimized size is important to minimize the unit hydrogen production cost. Finally, the effort to reduce the capital cost to produce the green hydrogen is necessary when increasing trend of carbon dioxide tax is considered.
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•Industrial-scale of single and hybrid system for green H2 production are proposed.•Techno-economic analysis is performed based on seasonal solar radiation data.•Optimized size of AWE and ESS is suggested for a green H2 production.•Outlook of a green H2 production cost is presented considering CO2 tax.
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