Low Pollutant Emissions Research Articles

Review of materials, functional components, fabrication technologies and assembling characteristics for polymer electrolyte membrane fuel cells (PEMFCs) – An update

Fuel cells use electrochemical processes to transform the chemical energy of a fuel into electrical energy, which is a key enabler for the shift to an H2-based economy. Because of their high energy conversion efficiency and low pollution emissions, fuel cells with polymer electrolyte membranes (PEMFCs) are regarded as being in frontline of commercialization for the transportation and automotive industries. However, there are two major hurdles to their future commercialization: cost and durability, which promote basic study and development of their components. In this article, we reviewed the materials, functional components, fabrication technologies and assembling characteristics related to PEMFCs. Platinum's significance as a catalyst in PEMFC applications stems from the fact that it beats all other catalysts in three critical parts: stability, selectivity, and activity. In order to create Pt rich surfaces of NPs, Pt metal is alloyed with d-block metals like Cu, Ni, Fe, and Co. PEMFC development is inextricably tied to the benefits and drawbacks of the Nafion membrane under various operating circumstances. Nafion membrane has some drawbacks, including poor performance at high temperatures (over 90℃), low conductivity under low humidification, and high cost. As a result, a variety of nanoscale additives are frequently added to Nafion nanocomposites to enhance the material's properties under fuel cell working conditions. Fiber composite based bipolar plates can deliver best performance. The assembly of PEMFC based on strap approach is being explored. The applications of PEMFC are also projected.

An Improved Data-Driven Integral Sliding-Mode Control and Its Automation Application

Circulating fluidized bed (CFB) boilers are widely used in industrial production due to their high combustion efficiency, low pollutant emissions and wide load-adjustment range. However, the water-level-control system of a CFB boiler exhibits time-varying behavior and nonlinearity, which affect the control performance of the industrial system. This paper proposes a novel data-driven adaptive integral sliding-mode control (ISMC) method for the CFB control system with external disturbances. Firstly, the scheme designs a discrete ISMC law based on the full-format dynamic linearization (FFDL) data model, which is equivalent to a nonlinear system. Furthermore, a new reaching law is proposed to quickly drive the system state onto the sliding-mode surface. The improved ISMC control scheme only utilizes the input–output data during the design process and does not require model information. After theoretically verifying the stability of the method proposed in this paper, it is further applied in MIMO systems. Finally, the control and practical effects of this method are evaluated by using the DHX25-1.25 CFB boiler installed in the special-equipment testing center. The experimental results show that, compared with the traditional sliding-mode control (SMC) and model-free adaptive-control (MFAC) methods, the improved control method can quickly track the given signal and exhibit resistance to noise interference. Furthermore, it can rapidly respond to changes in the working conditions of the CFB system.

Operational condition and furnace geometry for premixed C3H8/Air MILD combustion of high thermal-intensity and low emissions

MILD combustion is usually operated at relatively low thermal intensity to achieve uniform temperature field and low pollutant emissions, further understanding of its emission characteristics at high thermal intensity condition is required to widen its application. In the present numerical study of premixed C3H8/air MILD combustion, different operational conditions (equivalence ratio Φ and thermal input Pinput) and furnace geometries (side wall angle α and aspect ratio AR) are considered to reveal their correlations with pollutant emissions including CO, NOx and unburned hydrocarbon (UHC) at thermal intensities up to 1.06 MW/m3. By adopting reactor network calculation with detailed combustion chemistry, it is found that AR plays a notable role in controlling CO, NOx and UHC emissions, while NOx emission is insensitive to the variation of side wall angle. Both the CO and UHC emissions are related to the location of the internal recirculating vortex. Moreover, following the parametric study and NOx formation analysis, the optimized furnace geometry and operating condition of AR = 5, α = 0° and Φ = 0.6 are obtained to significantly reduce the pollutant emissions by 90 % for both C3H8 and CH4 fuels. The present investigation offers valuable insights into the high thermal intensity MILD combustion.

Effects of dimethyl ether blending on H2-fueled combustion characteristics and thermal improvement in fuel-lean condition

Micro-combustors play a pivotal role in micro powering system due to the potential for high energy density. However, addressing challenges such as incomplete combustion and high heat dissipation losses are essential for optimizing the working performance. So, the blended DME is proposed to micro-combustion, which acts as a promising oxygenated fuel with significant attention due to its higher reactivity, lower pollutant emissions, and carbon–neutral properties. However, the lack of dynamic models applicable to H2/DME fueled combustion in micro condition, so an optimized mechanism for blended H2/DME combustion is developed and validated. The results demonstrate that a reduced mechanism comprising 29 species and 106 reactions (M29-106*) can be commendably employed in micro H2/DME/air combustion simulation, according to the sensitivity analysis and reaction modification. Besides, investigation is conducted to explore micro-combustion characteristics of H2/DME/Air. The result shows that burning process and heat transfer are notably influenced by DME addition, leading to shifts in flame positions and adjustments in combustion reaction rates. So, DME addition enhances energy efficiency and modifies flame location through fluid field optimization and reduced heat loss. The thermal performance of the combustor is significantly improved with DME blending, resulting in higher radiative power and radiation efficiency. However, the choice of DME blending ratio must be carefully considered, as high blending ratios may compromise flame stability and lead to increased exhaust heat losses under fuel-lean conditions. Specifically, burning with 30 % DME addition achieves a radiative power of 20.24 W and a radiative efficiency of 40.57 % at the same chemical energy Ec = 49.9 W, which is 5.57 W and 11.17 % higher than that of pure H2-fueled combustion, respectively. These findings offer valuable insights for the design and optimization of micro-combustors, where compact and efficient power sources are required.

A Review on Compression-Ignition Engine Performance And Emissions With Hydrogen-Diesel Mixtures: Effect Of Operational Parameters

The combustion of conventional fuel in Compression-Ignition (CI) engines is generally understood as a primary cause of hydrocarbon exhaust emissions. Alternative fuels and hydrocarbon fuels can be mixed to lower pollution emissions while enhancing engine efficiency. Here, the various variables which impact emissions and engine efficiency are fully illustrated. Numerical work on the engine was done to examine the working and outflow patterns of a dual-fuel CI engine at various fuel combination ratios. In the test setup, diesel is used as main fuel and hydrogen and air as the controlling fuel. In order to formulate this special CI engine numerically, three-dimensional computer based analytical tools were used. For this method, n-heptane was chosen as reaction fuel and a reduced-reaction mechanism was taken into account. To investigate the soot formation rate inside the cylinder, the model by Hiroyasu-Nagel was developed. Here, a study looks into the performance effects on the variations of secondary fuel and its emissions. Presence of good amount of hydrogen during combustion results in better thermal efficiency and better performance. As the hydrogen rate increased, ignition timing was delayed as a result of a time lag in the OH component’s evolution. Meanwhile, Exhaust Gas Recirculation (EGR) and timing of the diesel incorporation strategies are also taken as important performance parameter.

Multi-Objective Experimental Combustor Development Using Surrogate Model-Based Optimization

Abstract The majority of premixed industrial gas turbine combustion systems feature two or more separately controlled fuel lines. Every additional fuel line improves the operational flexibility but increases the complexity of the system. When designing such a system, the goals are low emissions of various pollutants and avoiding lean blowout or extinction. Typically, these limitations become critical under different load conditions of the machines. Therefore, it is particularly challenging to develop combustors for stable and clean combustion over a wide operating range. In this study, we apply the Gaussian process regression machine learning method for application to burner development, with the aim of improving the process, which is often driven by a trial-and-error approach. To do so, a special pilot unit is installed into a full-scale industrial swirl combustor. The pilot features 61 positions of fuel injection, each of which is equipped with an individual valve, allowing to modify the fuel–air mixture close to the flame root in various degrees. In fully automatized atmospheric tests, we use the pilot system to train two surrogate models for different design objectives of the combustor, relevant for full load and part load operation, respectively. Once trained, the models allow for prediction for any possible injection scheme. In combination, they can be used to identify pilot injector configurations with an improved operation range in terms of low NOx emissions and part load stability. The adopted multimodel approach enables combustor design specifically for high operational flexibility of gas turbines, but can also be extended to other similar industrial development processes.

Integrated experimental and computational analysis of porous media combustion by combining gas-phase synchrotron [formula omitted]CT, IR-imaging, and pore-resolved simulations

Porous media combustion is a promising combustion technology that enables operation over an extended range of conditions, with a variety of fuels and low pollutant emissions. However, the lack of understanding of the interstitial combustion processes remains a major obstacle towards the application of this technology and the development of predictive models. To understand these processes, this study presents an integrated experimental and computational effort to examine porous media combustion. Specifically, a new experimental diagnostic method is employed that simultaneously combines synchrotron X-ray micro-computed tomography (μCT) and short-wavelength infrared thermometry. With this approach, the surface temperature and the 3D gas-phase temperature field are simultaneously measured inside a porous burner with micrometer spatial resolution. These measurements are then integrated into 3D pore-resolved simulations. This integrated approach enables a direct evaluation of current modeling capabilities, and a unique analysis of interstitial combustion in porous foams under realistic heating conditions. In light of these results, we discover that about 80% of the fuel consumption inside the matrix pores occurs far enough from the porous surface to be characteristic of a decoupled regime of preheated, but adiabatic flamelets. The remaining fuel consumption near the pore surface occurs in a non-adiabatic combustion mode. This insight and the proposed approach contribute to our fundamental understanding of porous media combustion, and suggest that multi-regime models could more accurately describe porous burners.

Повышение эффективности использования твердого топлива на промышленных ТЭЦ

Currently, in this country solid fuel at industrial thermal power plants, as a rule, is burned by a layer or flaring method in boilers with generation of steam which is directed to a steam turbine. This technology of generating thermal and electrical energy is characterized by relatively low efficiency and significant emissions of pollutants into the atmosphere. At the same time, the use of solid fuel in industrial energy with its preliminary gasification can significantly increase the efficiency of electricity generation and at the same time reduce the negative impact on the environment. The results of an analytical comparison of two schemes to use solid fuel in industrial energy are used as the material of the research. These two schemes are a traditional scheme and an alternative one based on its preliminary gasification. In this paper, to assess the effectiveness of the schemes under consideration, the scientific methodology of system analysis is applied. It allows us to consider any energy object as a unified system consisting of interrelated elements. The system analysis is carried out based on mathematical modeling of the technological process to obtain thermal and electrical energy. A complex balance mathematical model of an industrial thermal power plant with preliminary coal gasification is developed. The results of calculation using a mathematical model have shown that the construction of industrial combined‒cycle thermal power plants with preliminary coal gasification instead of traditional steam turbine ones will increase the key indicator of the energy efficiency of thermal power plants, coefficient of fuel utilization from 60 to 74 %. Based on the methodology of system analysis, an optimal thermal scheme of an industrial combined-cycle thermal power plant with preliminary coal gasification has been developed. Numerical values of the basic operating conditions of the thermal power plants and energy efficiency indicators have been determined using a mathematical model. The use of solid fuel at industrial thermal power plants with its preliminary gasification is a very promising direction to develop industrial energy in Russia since this method to extract the bound chemical energy of solid fuel can significantly increase the fuel utilization coefficient and the production of electrical energy and at the same time reduce emissions of contamination material into the atmosphere

Predicting the Choice of Online or Offline Shopping Trips Using a Deep Neural Network Model and Time Series Data: A Case Study of Tehran, Iran

This study examines the determinants of online and offline shopping trip choices and their implications for urban transportation, the environment, and the economy in Tehran, Iran. A questionnaire survey was conducted to collect data from 1000 active e-commerce users who successfully placed orders through both online and offline services in districts 2 and 5 of Tehran during the last 20 days of 2021. A deep neural network model was applied to predict the type of shopping trips based on 10 variables including age, gender, car ownership, delivery cost, and product price. The model’s performance was evaluated against four other algorithms: MLP, decision tree, LSTM, and KNN. The results demonstrated that the deep neural network model achieved the highest accuracy, with a rate of 95.73%. The most important factors affecting the choice of shopping trips were delivery cost, delivery time, and product price. This study offers valuable insights for transportation planners, e-commerce managers, and policymakers. It aims to help them design effective strategies to reduce transportation costs, lower pollutant emissions, alleviate urban traffic congestion, and enhance user satisfaction all while promoting sustainable development.

China's Energy Structure Problems and Optimization Suggestions from the Perspective of Low-carbon Economy

Energy consumption, technological level, and sustainable industrial system are crucial for developing a low-carbon economy. China's excessive reliance on coal has led to low energy utilization efficiency, which has become an important factor affecting the optimization of China's energy structure and further constraining the sustainable development of the economy. In this regard, this article attempts to explore the issues of China's energy structure from the perspective of a low-carbon economy, and proposes strategies for optimizing China's energy structure from the perspective of a low-carbon economy. In the context of developing a low-carbon economy, starting from China's specific national conditions, the government should play a guiding role, optimize China's energy structure step by step, and promote the development of new energy projects. Based on China's actual technological situation, technological upgrading and industrial structure transformation, we will focus on developing low-carbon related industries and strategic emerging industries. Only by continuously innovating and applying new energy can we achieve the transformation of energy application structure in the production and living fields, gradually shifting from high pollution and high emissions to low pollution and low emissions.

Dynamic Changes of Composition of Particulate Matter Emissions during Residential Biomass Combustion.

Residential biomass combustion in developing countries produces significant primary particulate matter (PM) emissions. Highly time-resolved aerosol mass spectrometry and aethalometer measurements were used to investigate the dynamic changes of emitted PM chemical composition from a typical improved stove burning with wood and crop straw in China. Combustion temperature and organic aerosol (OA) concentration increased quickly during the ignition stage. The flaming stage was characterized by high combustion temperature and high pollutant [including OA, black carbon (BC), inorganic salts, and polycyclic aromatic hydrocarbons (PAHs)] emissions, while the burnout stage is characterized by low combustion temperature and lower pollutant emissions. OA was the primary emitted species; emission factors of OA in the flaming stage were generally higher (24.5-792%) than those in the burnout stage. Mass spectral signatures of OA were obtained. The ratio of Cl-/OA for wood combustion (0.05 ± 0.01) is much lower than that from burning crop straw (0.32 ± 0.19). Hydrocarbon OA emissions dominated during the ignition and flaming stages. A high percentage of oxidized OA was emitted during the burnout stage. The relationship between PAHs and BC/OA emissions under different burning conditions was investigated, and PAHs may act as intermediate products in the conversion of OA to BC.

Experimental Evaluation of SOFC System Exposed to Marine Inclination Conditions

To comply with future emission regulations, the marine industry needs to reduce emissions. Marine actors are showing an increased interest in the application of Solid Oxide Fuel Cells (SOFCs) for ocean going ships, because of their high conversion efficiency, low pollutant emissions, and fuel flexibility. However, operation in ships is fundamentally different from stationary applications, since the installation rooms accelerate and incline due to wave-induced ship motions. This could lead to pressure variations in the fuel streams or detrimental mechanical stresses. So far it has not been extensively investigated what the consequences of inclinations and motions are on the operation of SOFCs. The goal of this research is to evaluate the influence of marine conditions in terms of static and dynamic inclinations on the operation, safety, and lifetime of SOFC systems. Ship motions are simulated with a one-axial oscillation platform. The inclination conditions the SOFC system is exposed to are derived from ship motion studies and marine regulations. The test campaign consists of two phases. In this paper, the results of the first test phase will be explained in detail. Moreover, the learned lessons and their implementation into the plan of the second test phase will also be shared.In the first phase of the test campaign, a 1.5kW SOFC system is inclined around two horizontal axes of rotation while producing power at nominal conditions. During the static experiments, the SOFC system is operated at fixed inclinations from -30 degrees to 30 degrees with steps of 5 degrees. In the dynamic experiment, the system is oscillated up to an angle of 30 degrees with frequencies of 0.025, 0.033, 0.05, and 0.1 Hz. The experiment showed no gas leakages or other significant safety risks during the experiment. However, for slow oscillations, relatively large deviations in several system parameters (e.g., fuel flow, stack voltage, and fuel utilisation) were found compared with the non-inclined operation. This indicates the natural frequency behaviour of particular components in the system. Although the deviations were much larger than in regular operation, the early stage indication was that these deviations do not result in safety issues or decreased system lifetime.The second phase of the test campaign was focused on including a larger range of possible ship motions and increasing test durations. An additional aim was to find the physical cause of the deviations in system parameters during oscillations. Additionally, a 100h test on one oscillation condition is included to evaluate whether the ship motions could cause increased cell degradation. Furthermore, several part-load conditions are included in the experiment.The results of the experiments are used to propose design improvements for SOFC systems that require to be inclined or accelerated. These proposals contribute to the marinization of SOFC systems. Furthermore, the results will be used to help class societies defining proper regulations for SOFC implementation in seagoing vessels. Figure 1

Enhancing the Cathodic Performance of LSM Via Nanostructured Surface Decoration with Infiltrated Sm0.5Sr0.5CoO3-Δ

The Solid Oxide Fuel Cell (SOFC) is getting attention from next-generation electrochemical energy conversion devices with high efficiency and low pollutant emission. But the high operating temperature in SOFC can lead to problems like high cost, difficult sealing, and fast degradation. To alleviate this problem, Intermediate temperature SOFC (IT-SOFC) has become an adequate alternative. But, as the operating temperature decreased, the Oxygen reduction reaction (ORR) also decreased, contributing to performance degradation and efficiency loss. The infiltration method, effectively improving the performance of the SOFC electrode, is one of the most effective ways. However, this method has been limited due to the multi-step process and instability of long-term operation. In this study, we suggest a new process that combines the infiltration and spray method with co-sintering to diminish the multi-step. We fabricated a cathode in which the LSM and Sm0.5Sr0.5CoO3-δ infiltration solvent coated simultaneously by the spray process and co-sintered. And we measured the cell performance and stability. Consequently, when applied as electrolyte-supported cells at 1073K, performance is measured by exhibiting a maximum power density of 0.986W cm-2 in fuel cell mode and electrolysis performance of 0.878A cm-2 at 1.3V. The result of this study was 0.724W higher than that of the bare LSM electrode. Figure 1

A physically based air proportioning methodology for optimized combustion in gas-fired boilers considering both heat release and NOx emissions

Ensuring the reliable operation of industrial boilers with high production efficiency and low pollutant emissions remains a significant challenge due to the complex chemical and physical reactions that occur within the boiler system. To address this issue, the present research introduces a novel air proportioning methodology for optimized combustion in gas-fired boilers, incorporating real-world data, numerical-computational technologies, and a normalization method. Initially, an average discrepancy of 11.32% is observed between the airflow recorded by the sensors and the actual airflow in the gas-fired boiler. The optimum oxygen levels in the flue gas are determined by striking a trade-off between heat release and pollutant emissions. At loads of 35%, 55%, 75%, and 95%, the recommended oxygen levels under equal-weighted conditions are 3.62%, 3.75%, 3.82%, and 3.91%, respectively. Furthermore, this research also considers the oxygen levels when there are non-equal weightings between heat release and nitrogen oxide (NOx) emissions. At 55% load, the weighting between heat release and pollutant emissions shifts from 1:1 to 1:2, necessitating an increase in the oxygen concentration from 3.75% to 4.30%. The air proportioning methodology proposed in this study offers an efficient framework for optimizing combustion in gas-fired boilers.

Research and Development of an Industrial Denitration-Used Burner with Multiple Ejectors via Computational Fluid Dynamics Analysis

Nowadays, since the air pollution problem is becoming global and denitrification is efficient to control nitrogen oxides, research and development of burners with low pollutant emissions in industries are urgent and necessary due to the increasingly severe environmental requirements. Based on the advanced CFD (computational fluid dynamics) numerical analysis technique, this work focuses on developing an industrial denitration-used burner, aiming to decrease the emission of nitrogen oxides. A burner with multiple ejectors is proposed, and the gas premixing and combustion process in the burner are systematically studied. Firstly, for the ejector, the well-known orthogonal experiment method is adopted to reveal the premixing performance under different structural parameters. Results show that the angle and number of swirl blades have significant effects on the CO mixing uniformity. The CO mixing uniformity first decreases and then increases with thr rising swirl blade angle, and it enhances with more swirl blades. Through comparison, a preferred ejector is determined with optimal structure parameters including the nozzle diameter of 75 mm, the ejector suction chamber diameter of 290 mm, the blade swirl angle of 45∘, and the swirl blade number 16. And then, the burners installed with the confirmed ejector and two types of flues, i.e., a cylindrical and a rectangular one, are simulated and compared. The effects of ejector arrangements on the temperature distributions at the burner outlet are analyzed qualitatively and quantitatively. It is found that the temperature variances at the outlets of R2 and C1 are the smallest, respectively, 13.12 and 23.69, representing the optimal temperature uniformity under each type. Finally, the burner of the R2 arrangement is verified with a satisfied premixing performance and combustion temperature uniformity, meeting the denitration demands in the industry.

The effect of 1-octanol blending on the multi-stage autoignition of conventional diesel and HVO fuels

Alternative fuels can reduce the carbon intensity of diesel engine use, and a detailed understanding of the combustion process for these fuels can minimize resulting fuel consumption and emissions. 1-Octanol has been considered as an alternative diesel fuel, but little work evaluating its combustion process in detail exists. In this work, ignition of 1-octanol, both pure and in blends with conventional and renewable diesel base fuels, is analyzed in a constant volume combustion chamber and a modified Cooperative Fuels Research Octane Rating engine operating in homogeneous charge compression ignition combustion mode. 1-Octanol blending reduced the derived cetane number of either base fuel, but modest increases in chamber temperature at injection could compensate for even dramatic reductions in derived cetane number. It was further found that greater amounts of low-temperature heat release were required to reach main ignition as the 1-octanol blending volume fraction was increased in the constant volume combustion chamber. This finding is attributed to the changing local equivalence ratio, as the reacting spray diffuses further into the chamber and approaches the (lean) global equivalence ratio as the ignition delay grows. Finally, it was found that, despite lowering the derived cetane number, 1-octanol blending enhanced the reactivity of the conventional diesel fuel observed in the variable compression ratio engine. This finding is attributed to the higher rates of hydrogen abstraction from the weaker average C–H bonds in 1-octanol, as hydrogen abstraction governs intermediate temperature heat release. These findings clarify the effect of 1-octanol on physical processes and the various chemical regimes of heat release in compression ignition. The dependence of the effects of 1-octanol blending on the base fuel are emphasized, as these can inform the deployment of 1-octanol as a diesel blendstock. Application of these results can support the optimization of conventional combustion strategies for use with 1-octanol, as well as the development of 1-octanol-fueled low-temperature combustion strategies with the associated promise of very low criteria pollutant emissions.

Asymmetric effect of renewable and non-renewable energy consumptions on corporate cash holdings: new panel data evidence from BRICS economies

PurposeIn the recent wake of environmental sustainability, more attention has been paid to the consumption of specific energy types. However, how the consumption of such energy alternatives influences multiple corporate-level decisions has not yet been well explored in the literature. The current analysis bridges this deficiency in literature by exploring the empirical relationship between energy alternatives and cash holdings.Design/methodology/approachFor empirical analysis, the authors sample the non-financial sector enterprises founded in five BRICS economies and employ the system GMM and fully modified ordinary least square techniques to establish the regression. The selection of econometric techniques is subject to the existence of endogeneity and cointegration.FindingsThe estimated coefficients reveal a significant negative effect of renewable energy (REC) while a significant positive impact of non-renewable energy consumption (FFE) on cash holdings. Referring to low pollution emissions, less operational risk and a cheap source of energy, the more consumption of renewable energy reduces the motives of cash holdings. Primarily, the current analysis advocates an important policy regarding the utilization of renewable energy as industrial fuel inputs because it has a material impact on cash holdings and also ensures environmental sustainability.Practical implicationsThis study has equal policy outputs for industry officials, policy regulators and environmental economists. Corporate managers should do more focus on transforming the energy needs from non-renewable to renewable as such transformation can benefit in terms of both, i.e. environmental sustainability and low cash holdings.Originality/valueContemporary literature mainly highlights the determinants of energy consumption. However, it is less known how the consumption of specific energy sources affects the firm's cash-holding decisions. Thus, this study enriches both energy economics and financial economics literature by offering cutting-edge evidence on the sustainable role of REC in declining cash holdings.

Review of CO2 Adsorption Materials and Utilization Technology

This article introduces the recent research status of CO2 adsorption materials and effective ways of CO2 resource utilization. Molecular sieves have the advantages of a large specific surface area, a wide pore size range, recyclability, and good chemical and thermal stability. Metal–organic frameworks have diverse structures and broad application prospects. The captured CO2 is converted into valuable chemicals such as acids, alcohols, hydrocarbons, and esters as raw materials. The rapid development of biomass energy utilization of CO2, with strong biological adaptability, high yield, low production cost, and low pollutant emissions, is a feasible method to reduce CO2 emissions. This article analyzes the current research status of CO2 capture, conversion into chemicals, biomass energy, and industrial utilization from the perspective of catalytic conversion.

The Effects of a Cross-Border Freight Railway Project on Chinese Cities’ Green Innovation Intensity: A Quasi-Natural Experiment Based on the Expansion of the China Railway Express

This paper intends to clarify whether launching a cross-border freight railway project will cause adverse impacts on cities’ green innovation intensity. Based on the construction and operation of the China Railway Express, the impact mechanism of this cross-border freight railway project on cities’ green innovation is theoretically analyzed. Through using the data of 284 prefecture-level cities in China from 2017 to 2019, the effects of the China Railway Express on green innovation intensity are empirically tested by adopting the differences-in-differences method. The results show the following: 1. launching the China Railway Express project has a direct negative impact on cities’ green innovation intensity; 2. the China Railway Express has indirect positive impacts on green innovation intensity through increasing the foreign trade volume of cities as well as reducing the level of industrial specialization, and has an indirect negative impact on green innovation intensity through reducing the strictness of environmental regulations; 3. the radius of the impact coverage of the China Railway Express is 150 km, and its impact on surrounding cities is funnel-shaped; 4. the China Railway Express will cause a negative impact on green innovation intensity in large cities, cities with lower pollution emissions, and cities of Eastern China and Western China. Taking these findings into account, some policy implications are proposed.

Exploring the Benefits of Karanja-Oil-Derived Biodiesel-Water Emulsion as a Potential Fuel for Diesel Engines Operated with High-Pressure Fuel Injection Systems

<div>Biodiesel is a suitable alternative to diesel because of its carbon neutrality, renewability, lubricity, and lower pollutant emissions. However, extensive research indicates higher oxides of nitrogen (NO<sub>x</sub>) emissions with biodiesel. A practical method to combat this problem is utilizing water and biodiesel as emulsions. The effect of biodiesel-water emulsion in high-pressure fuel injection systems is not fully explored in the existing literature. The present study addresses this research gap by utilizing biodiesel-water emulsions in a modified light-duty diesel engine. The governor-controlled injection system was adapted to a fully flexible electronic system capable of high-pressure injection. Unlike other literature studies, the fuel injection timings were optimized with biodiesel-water emulsions to maximize brake thermal efficiency (bte) at every load condition. In a novel attempt, the biodiesel source, i.e., raw Karanja oil (RKO), a triglyceride, was utilized as the surfactant to stabilize the biodiesel-water emulsions containing 6%, 12%, and 18% water. The emulsions reduced the ignition delay and cylinder pressures, with less-intense premixed combustion and a more significant diffusion phase combustion than biodiesel. The emulsions also present a delayed combustion phasing following the injection timing trends. Among the tested emulsions, at 5.08 bar brake mean effective pressure (BMEP), 18% biodiesel-water emulsion resulted in an 18% reduced brake specific fuel consumption (bsfc), 5% increase in bte, 30% and 7% mitigation in NO<sub>x</sub> and smoke levels, with an increase of 10% and 28% for unburned hydrocarbon (HC) and carbon monoxide (CO) emissions.</div>