Total Flow Rate Research Articles

PROSPECTS AND PROBLEMS OF USING LOCAL WATER RESOURCES FOR IRRIGATION IN THE BASINS OF SMALL RIVERS OF THE FOREST-STEPPE OF UKRAINE

On the example of a separate agricultural farm located in the basin of the small Manzhelia River within the Left Bank Forest Steppe, the approaches to the selection of potential sources of irrigation and the specifics of determining the volumes of local water resources intended to be used for irrigation, as well as the areas of possible irrigation in the absence of existing irrigation systems, are given. The results of the research indicate that the prospects for the development of land irrigation on farmland can be mainly provided subject to the combined use of surface runoff accumulated in ponds on the Manzhelia River and groundwater admissible for extraction, taking into account their quality. It was determined that influenced by a complex of anthropogenic factors, the river runoff sharply decreased compared to natural conditions, and the feeding of river course ponds during the entire low water period occurs only due to lateral inflow. Based on calculations it was determined that in average and low-water years, the volumes of surface and ground inflow to the cascade of ponds for the period from June to September are smaller than evaporation losses. Under such conditions, the use of the river runoff for irrigation is possible only due to the accumulation of flood and, partially, high water runoff. The calculations of flood runoff volume for March - April at the gate of the lower pond indicate the impossibility of using water from it for irrigation in very low-water years, as well as the dependence of runoff use for irrigation in low-water years on the pre-flood filling level of the ponds. It was determined that up to 0.8 million m3 of water can be used for irrigation in medium-water years, and up to 1.4 million m3 in high-water years, which will provide irrigation on an area of 400 and 700 hectares, respectively (having an irrigation rate of 2000 m3/ha). The possibility of installing at least 40 water intake wells within the territory of the farm with a total flow rate of 20-24 thousand m3/day and a total water intake during the irrigation period of about 1.5 million m3 has been substantiated. This will make it possible to irrigate 750 hectares of land having an irrigation rate of 2000 m3/ha, and at least 1000 hectares having an irrigation rate of 1500 m3/ha. It is focused on the mandatory preliminary investigation of water quality for irrigation, which for many small rivers and aquifers is a limiting factor when using local water resources for the construction of irrigation systems.

Effect of Biopipe Total Flowrate on Venturi Aerator Performance

There is a vacuum created when water goes past a pipe constriction. Air may be pulled into the main flow by drilling a hole in the pipe near where the vacuum happens. Venturi aerator is an example of the application in action. A vacuum is formed at the suction holes of the Venturi tube when there is a small difference in pressure between the input and output sides. To demonstrate the link between total flow rate and Venturi aerator performance, a Venturi aerator (model 1584) was introduced at a specific point in a Biopipe system. For this purpose, a physical model on a pilot scale was constructed and installed in an existing sewage treatment plant. Dissolved oxygen concentrations were measured at four locations along the Biopipe at different values of wastewater flowrates. The study results showed that raising the total flow rate increased the amount of air injected by the Venturi aerator. When the total flow rate was less than 4 m3/hour, the Venturi aerator stops sucking air and produces negative consequences.

Heat-transfer modeling of the gas gap under a wafer

The wafer temperature is a critical observable in semiconductor manufacturing. One of the various mechanisms determining this temperature is the heat transfer in a gas gap between the wafer and the electrostatic chuck (ESC). Various correlations for this heat transfer are available. However, to calculate more accurately the spatial distribution of this temperature, computing the flow in this gap is necessary. With this motivation in mind, this paper presents a computational fluid dynamics model (CFD) for the flow in the wafer-ESC gap that is designed to be easy to implement in industrial CFD codes. This model is tested in various channel-flow problems and then applied to a generic wafer-ESC configuration. For this configuration, CFD results show that varying the flow rate split between three zones, or the total flow rate, or the rugosity of the wafer affect the heat transfer coefficient and its spatial variation. This is important since controlling this variation would allow to maintain a uniform wafer temperature. The model could be used in more realistic wafer-ESC configurations to consider many other parameter variations, such as the size of injection holes, a radially varying gap distance, or the use of many injection zones. From a broader viewpoint, the model is applicable to vacuum problems other than the wafer-ESC configuration.

Consideration of fouling by scaling in the sizing of flat plate solar collector networks

In this work, the effects of fouling on the performance of flat plate solar collector networks that operate with water as the thermal fluid are studied, and design considerations are put forward to be used in the sizing of these systems from the thermal and hydraulic points of view. The quantification of the effects produced by scaling is carried out through a mathematical model that predicts the deposition on the walls of the tubes. The model considers that CaCO3 is the only compound present in the fouling layer. Results indicate that for a volumetric flow rate of 3.78 l/min and assuming a CaCO3 concentration of 250 ppm, in a period of six months, the maximum outlet temperature that can be obtained in a day falls 1.5 °C and the pressure drop increases four times. It is shown that it is advisable to design a network of solar collectors considering scaling. The case study indicates that to supply a total flow rate of 48 l/min at a temperature of 70 °C, the design considering scaling requires 220 collectors and a volumetric flow rate of 4.8 l/min per line with a total annualized operating cost of $343,300 Mx.

Microfluidic-Assisted ZIF-Silk-Polydopamine Nanoparticles as Promising Drug Carriers for Breast Cancer Therapy.

Metal-organic frameworks (MOFs) are heralded as potential nanoplatforms for biomedical applications. Zeolitic imidazolate framework-8 (ZIF-8), as one of the most well known MOFs, has been widely applied as a drug delivery carrier for cancer therapy. However, the application of ZIF-8 nanoparticles as a therapeutic agent has been hindered by the challenge of how to control the release behaviour of anti-cancer zinc ions to cancer cells. In this paper, we designed microfluidic-assisted core-shell ZIF-8 nanoparticles modified with silk fibroin (SF) and polydopamine (PDA) for sustained release of zinc ions and curcumin (CUR) and tested these in vitro in various human breast cancer cells. We report that microfluidic rapid mixing is an efficient method to precisely control the proportion of ZIF-8, SF, PDA, and CUR in the nanoparticles by simply adjusting total flow rates (from 1 to 50 mL/min) and flow rate ratios. Owing to sufficient and rapid mixing during microfluidic-assisted nanoprecipitation, our designer CUR@ZIF-SF-PDA nanoparticles had a desired particle size of 170 nm with a narrow size distribution (PDI: 0.08), which is much smaller than nanoparticles produced using traditional magnetic stirrer mixing method (over 1000 nm). Moreover, a properly coated SF layer successfully enhanced the capability of ZIF-8 as a reservoir of zinc ions. Meanwhile, the self-etching reaction between ZIF-8 and PDA naturally induced a pH-responsive release of zinc ions and CUR to a therapeutic level in the MDA-MB-231, SK-BR-3, and MCF-7 breast cancer cell lines, resulting in a high cellular uptake efficiency, cytotoxicity, and cell cycle arrest. More importantly, the high biocompatibility of designed CUR@ZIF-SF-PDA nanoparticles remained low in cytotoxicity on AD-293 non-cancer cells. We demonstrate the potential of prepared CUR@ZIF-SF-PDA nanoparticles as promising carriers for the controlled release of CUR and zinc ions in breast cancer therapy.

A nozzle simulation chip toward high-throughput formation of curcumin-loaded zein nanoparticles with tunable properties.

Size of nanoparticle (NP) is a crucial factor in determining its applicability to various fields. This study aimed to develop a nozzle chip for the scalable formation of self-assembled curcumin-loaded zein NPs with tunable properties. A four-factor (zein concentration in dispersed phase, ethanol concentration in continuous phase, flow rate ratio, and total flow rate), three-level Box-Behnken design on the measured responses (particle size and polydispersity index [PDI]) was established. The particle size and PDI, ranging from 194.43 to 420.51nm, and 0.089 to 0.219, respectively, were readily controlled by adjusting four factors. Under the optimal conditions of 6% zein, 0% EtOH, the flow rate ratio of 7, and a total flow rate of 8mL/min targeting higher production rate, the particle size of 306.02±1.52nm (mean±standard deviation) and the PDI of 0.135±0.001 were obtained. High throughput for zein NP production (86.4g/day) was reached, which was 200 and 960 times higher than using microfluidic and electrospraying techniques, respectively. Curcumin-loaded zein NPs under the abovementioned experimental conditions were successfully prepared via the nozzle chip with the encapsulation efficiency of 64.29%±0.29%, a loading capacity of 3.06%±0.01%, enhanced stability, and improved in vitro antioxidant properties. Curcumin was primarily released from zein NPs in the simulated intestinal phase. This study demonstrated that the property of self-assembled zein NPs can be tuned by altering the operating parameters using the nozzle simulation chip. The results suggest that this approach has potential for use in the food and pharmaceutical industries, particularly for curcumin encapsulation. PRACTICAL APPLICATION: The fabricated nozzle chip is a promising technology to obtain zein nanoparticles (NPs) with enhanced productivity and narrow particle size distribution. It can be easily adopted to spray drying process. Besides, the nozzle chip shows the potential for the large-scale production of bioactive loaded zein NPs in the food or pharmaceutical industries.

Controlling polymersome size through microfluidic-assisted self-assembly: Enabling ‘ready to use’ formulations for biological applications

The self-assembly of poly(ethylene glycol)-block-poly(trimethylene carbonate) PEG-b-PTMC copolymers into vesicles, also referred as polymersomes, was evaluated by solvent displacement using microfluidic systems. Two microfluidic chips with different flow regimes (micromixer and Herringbone) were used and the impact of process conditions on vesicle formation was evaluated. As polymersomes are sensitive to osmotic variations, their preparation under conditions allowing their direct use in biological medium is of major importance. We therefore developed a solvent exchange approach from DMSO (Dimethylsulfoxide) to aqueous media with an osmolarity of 300 mOsm L−1, allowing their direct use for biological evaluation. We evidenced that the organic/aqueous solvent ratio does not impact vesicle size, but the total flow rate and copolymer concentration have been observed to influence the size of polymersomes. Finally, nanoparticles with diameters ranging from 76 nm to 224 nm were confirmed to be vesicles through the use of multi-angle light scattering in combination with cryo-TEM (Cryo-Transmission Electron Microscopy) characterization.

3D MHD analysis of prototypical manifold for liquid metal blankets

The water-cooled lead lithium (WCLL) and the dual-cooled lead lithium (DCLL) are two of the breeding blanket (BB) concepts that the EUROfusion consortium is pursuing in the framework of the development of the fusion reactor industrial demonstrator DEMO. Both involve the use of a liquid metal (LM) as working fluid, the lead-lithium eutectic alloy (PbLi), due to its excellent thermal properties and the possibility to serve as both the blanket coolant and tritium breeder and carrier. Unfortunately, due to the high electrical conductivity of LMs, their motion is influenced by the magnetic field used in the reactor to confine the plasma, generating a complex phenomenology which is studied by magnetohydrodynamics (MHD). In this work, a representative prototypical manifold of a BB bottom feeder is investigated for different configurations with the custom phiFoam solver, capable of simulating unsteady, incompressible and isothermal MHD flow. The aim of this study is to investigate which configuration minimizes the flow imbalance in the manifold for the WCLL or in the poloidal breeding zone channels for the DCLL. The distribution of the flow rate among the channels is strongly influenced by the position of the feeding pipe (FP) and by the development of the MHD internal layer near the expansion, which generates important jets close to the lower plate and the upper one, where the channels are attached. The channel aligned with the FP is the one carrying most of the flow, from 55% to 82%, while in the more distant one the flow is almost stagnant, carrying from 17% to 6% of the total flow rate. The total pressure loss is also estimated and its functional dependence on the manifold configuration is discussed.

Heat dissipation performance research between drop contact and immersion contact of lithium-ion battery cooling

Direct drop contact and immersion contact liquid cooling technology have proven to be effective in heat transfer and temperature control for lithium-ion batteries. In this study, a novel drop contact cooling system with a multi-hole outlet pipe was proposed to enhance the uniformity of coolant outflow in the reservoir based on an analysis of the contact cooling system for lithium-ion battery modules. The heat dissipation performances between the drop contact cooling system (DCCS) and immersion contact cooling system (ICCS) were compared through numerical simulations and experiments. The numerical results demonstrate the DCCS can achieve lower maximum temperature and temperature differences in the lithium-ion battery module. The experiment tests were conducted at a total flow rate of 560 mL/min to compare the performance of the battery module between DCCS and ICCS. The results show that the maximum temperature of the battery module with DCCS was approximately 3.9 °C lower than that with ICCS with the temperature difference of 4 °C. It can be inferred that DCCS of lithium-ion battery modules under the same conditions can lead to superior heat dissipation effects compared with ICCS.

A new oxidation flow reactor for the measurements of secondary aerosol formation: Characterisation and a case study

Oxidation flow reactors (OFRs) have been extensively used to investigate secondary aerosol formation of the ambient air or emission sources such as biomass burning or vehicular emissions, and they can provide useful information on the mechanisms of secondary aerosol formation. Here we present the design and characteristics of a newly developed OFR, named the Rapid Aerosol Ageing Device (RAAD). The RAAD was specially designed to provide time-resolved and fast-response chemical evolution of aged aerosols and can be applied to investigate how oxidative stress levels change upon ageing. The characterisation experiments included optimisation of the flow rate, residence time distributions for gas and particles, transmission efficiencies of particles, OH exposures with varying O3 concentrations and relative humidity conditions. Results show that the RAAD has near-laminar flow conditions at a total flow rate of 45 slpm with a low surface-area-to-volume ratio of 26.52 m-1. Wall losses for particles with mobility diameters greater than 40 nm are negligible, and narrow residence time distributions of gas and particles were observed. These features allow a better response to the ageing of rapid-changing emission sources, and measurements can be taken directly for instruments demanding high flow rates without diluting the samples. Additionally, the performance of the RAAD was further evaluated by measuring the secondary aerosol formation of biomass burning emissions. The organic aerosol enhancement ratios were comparable with other ageing studies, with an average value of 1.31 ± 0.05. In addition, the absorption Ångström exponent (AAE) value decreased from 1.7 ± 0.05 (primary emissions) to 1.4 ± 0.06 upon ageing. Overall, the RAAD is suitable for studying the formation mechanisms of photochemically aged aerosols from emission sources, and future work will aim to provide more details on the secondary aerosol production from ambient air.

Performance improvement of photovoltaic/thermal systems by using twisted tapes in the coolant tubes with different cross-section patterns

A numerical technique is applied to study the efficacy of integrating twisted tapes to the collector of Photovoltaic/Thermal (PV/T) units on the system performance when the tubes with different cross-sections are used. Hence, computational fluid dynamics is employed to evaluate PV/T systems with and without twisted tapes when using cylindrical, rectangular, and triangular patterns for the tube cross-section. The effect of employing twisted tapes with various pitch-to-width ratios (YD) of 3, 4 and 5 is evaluated. The impact of the total inlet mass flow rate ranging from 25 to 150 Lhr is also studied. To analyze the system performance the evaluation of energy and exergy is performed. The results demonstrated that the triangular pattern is the optimum pattern for the tube cross-section without twisted tapes. However, inserting a twisted tape makes the cylindrical tube superior to other designs from electrical and thermal aspects. A collector employing a cylindrical tube with and without a twisted tape could increase the module's electrical efficiency by 7.2 and 9%, respectively. Also, it was observed that integrating twisted tape with the lowest value of pitch-to-width ratio could decrease the surface temperature by 3.2 and 17.55 K compared to the systems with cylindrical tubes and PV alone.

Microfluidic preparation and thermal properties of HMX@PDA@MO

Metal oxides can effectively promote the thermal decomposition of energetic materials. However, the traditional physical mixing process has potential safety hazards and cannot achieve uniform and stable coating. To address this issue, this study provides adhesion sites for metal oxides through the rough coating formed by polydopamine on the surface of HMX, which improves the coating stability. Taking advantage of the safety and efficient mixing of microfluidic technology, HMX@PDA@MO samples with good dispersion were prepared. The samples were characterized by SEM-EDS, XRD and DSC. The XRD results demonstrate the successful preparation of HMX@PDA@CuO and HMX@PDA@PbO samples. SEM-EDS images show that polydopamine forms a rough coating on the surface of HMX, and the increase in the total flow rate is beneficial to enhance the dispersion of metal oxides. The DSC data showed that the addition of 3% and 20% CuO advanced the thermal decomposition temperature and apparent activation energy of HMX@PDA by 0.3K, 40.13 kJ·mol−1 and 2K, 108.83 kJ·mol−1, respectively, PbO is 0.1K, 111.94 kJ·mol−1, and 4.5K, 205.02 kJ·mol−1. It shows that the increase of metal oxide content will promote thermal decomposition. For HMX, PbO has better catalytic activity than CuO. PbO has better catalytic activity than CuO for HMX.

Pore‐Scale Imaging of Multiphase Flow Fluctuations in Continuum‐Scale Samples

AbstractRepresentative elementary volumes (REVs) are an important concept in studying subsurface multiphase flow at the continuum scale. However, fluctuations in multiphase flow are currently not represented in continuum scale models, and their impact at the REV‐scale is unknown. Previous pore‐scale imaging studies on these fluctuations were limited to small samples with mm‐scale diameters and volumes on the order of ∼0.5 cm3. Here, we image steady‐state co‐injection experiments on a one‐inch diameter core plug sample, with nearly two orders of magnitude larger volume (21 cm3), while maintaining a pore‐scale resolution with X‐ray micro‐computed tomography. This was done for three total flow rates in a series of drainage fractional flow steps. Our observations differ markedly from those reported for mm‐scale samples in two ways: the macroscopic fluid distribution was less ramified at low capillary numbers (Ca) of 10−7; and the volume fraction of intermittency initially increased with increasing Ca (similar to mm‐scale observations), but then decreased at Ca of 10−7. Our results suggest that viscous forces may play a role in the cm‐scale fluid distribution, even at such low Ca, dampening intermittent pathway flow. A representative elementary volume study of the fluid saturation showed that this may be missed in smaller‐scale samples. Pressure drop measurements suggest that the observed pore‐scale fluctuations resulted in non‐Darcy like upscaled behavior. Overall, we show the usefulness of large field‐of‐view, high‐resolution imaging to bridge the gap between pore‐ and continuum‐scale multiphase flow studies.

Low-temperature fabrication of silicon nitride thin films from a SiH4+N2 gas mixture by controlling SiNx nanoparticle growth in multi-hollow remote plasma chemical vapor deposition

High-quality amorphous silicon nitride (SiNx) thin films were fabricated by the controlled growth of nanoparticles during SiH4+N2 multi-hollow remote plasma chemical vapor deposition (CVD) at low substrate temperature 100 °C. Measurements from quartz crystal microbalances showed that a higher amount of nanoparticle incorporation in the SiNx film corresponded to a higher ratio of N/Si in the film, implying that the nanoparticles were nitrided in the plasma phase. We controlled the size of the nanoparticles by tuning the gas flow ratio of N2/SiH4 and the total gas flow rate. Transmission electron microscopy and energy-dispersive X-ray spectroscopy showed that smaller nanoparticles in the plasma led to a higher ratio of N/Si in the film and a lower hydrogen content. We attribute these results to the low heat capacity and large specific surface area of the nanoparticles, which enabled active chemical reactions on their surface in the plasma.

Removal of NOx using ozone injection and subsequent absorption in water

In nuclear reprocessing plant reduction of the nitric acid from the high level radioactive liquid waste is accomplished by the addition of formaldehyde. A significant amount NOx is generated during this conventional acid killing process. In this case NO oxidation followed by NO2 absorption is considered as a suitable option for NOx eradication, which also produces reusable nitric acid. Hence, investigations to explore the NO oxidation in the presence of O3 have been carried out for a relatively large system where the total flow rate of gas stream was 800 SLPM (52.4 m3/ h at 25 °C) and the concentration of NO was 480 ppm. It was observed that the concentration of NO decreases with the increase in the concentration of O3 added. A mathematical model has also been developed to predict the concentration of the gaseous components at the exit of the ozonization chamber. Model calculation shows that the reaction between NO and O3 is completed within fraction of a second. Further investigation on the absorption of NO2 in water was carried out by passing the exhaust gas through a scrubber. The absorption of NO2 in water leads to the formation of NO. An attempt has been made to enhance the performance of the water scrubber by injecting ozone into the gas phase during NO2 absorption. The model prediction reveals that N2O5 is the ultimate fate of the NO2 in the presence of O3. The evolution of N2O5 can be considered as two-step process. Reaction between NO2 and O3 is slow and the rate controlling step. On the contrary NO3 reacts quite rapidly with remaining NO2 and produces N2O5.

Description and Analytical Modeling for a Solid Block Cross-flow High Temperature Heat Exchanger

In this report, the design specifics, and performance modeling results, for a simple, solid metal block, liquid–liquid cross-flow heat exchanger, intended for high temperature applications, are given. The design consists of a solid block of metal, with cylindrical channels providing the cross-flow passageways for two non-mixing liquids. In this design, all flow channels are separated by a certain minimum thickness of the host solid block material. This particular design is limited by the length of pores that can be machined from a solid block. In this study, a simple heat transfer model, appropriate for such an exchanger, was used to estimate what values of effectiveness might be obtainable while keeping the size of the exchanger as compact as possible. The effects of channel length and spacing, liquid specific heat and viscosity and block material conductivity on exchanger effectiveness are considered and results reported. The model predicts that for a cubic exchanger of side length 8.25 cm with 50 channels per side at a diameter of 3.0 mm each, for a particular high temperature situation using molten salts, with an inlet and outlet temperature difference of around 170 K, an effectiveness of 0.4 can be achieved with a total mass flow rate of 0.5 kg $$\cdot$$ s $$^{-1}$$ along with a Reynolds number of less than 2000.

CFD Prediction of a Double Impulse Burner for Glass Furnaces

Recently, growing environmental awareness has radically changed the way the problems and priorities of industry are dealt with. Energy issues have become an issue of primary importance, both in terms of consumption and polluting emissions. However, for the green transition to happen, the first step is to have a deeper knowledge of the phenomena involved in processes with a special focus on combustion. The glass industry is one of the most energy-intensive since a temperature of over 1400 °C is required to keep glass molten, with a large consumption of natural gas used for combustion. A fundamental element to control the process is the burner. In this study, the CFD (Computational Fluid Dynamics) prediction of the internal streams repartition and the velocity profile at the exit, at different geometrical setups and operating conditions, of an industrial burner for glass furnaces is presented, with the aim of developing a surrogate model to provide these two important quantities quickly. The study of the repartition of the mass flow inside a double impulse burner and the subsequential velocity profile outside the burner is a novelty in the glass industry. The CFD prediction of the operating conditions is a crucial aspect because it is an essential boundary condition for the simulation of the reactive process from the diffusive flame found in glass furnaces. Different operating and geometrical conditions of the burner have been tested using Ansys CFX code, and results (velocity profile and mass flow repartition) have been organized in surrogate models. Results showed that the repartition of the fuel streams is mainly influenced by the position of the barrel, while the total flow rate is strongly influenced by the total inlet pressure. The internal flow varies from 20% to 50% of the total mass flow inside the burner, while the velocity magnitude outside the burner varies from 80 to 300 m/s approximately. The reconstruction of velocity profiles at the exit of the burners with surrogate models showed an acceptable match with numerical simulations.

Preparation and properties of the biogas decarbonization byproduct of nano-CaCO3 in a microfluidic device and computational fluid dynamics simulation

Biogas decarbonization is a key step in increasing the calorific value of biogas to meet demand. However, the release of CO2 into the atmosphere from the biogas decarbonization process increases carbon emissions. The use of Ca(OH)2 slurry to absorb and remove CO2 can achieve a carbon-free biogas purification process, and it is also an effective method for preparing CaCO3. This study prepared biogenic nano-CaCO3 using CO2 from biogas decarbonization with a newly fabricated microfluidic device and novel microfluidic chips were also made. The reaction pH, microfluidic chips, and total flow rate were parameters varied and studied for optimization. In addition, computational fluid dynamics (CFD) simulated the flow mixing and mass transfer of Ca(OH)2 solution and CO2-rich water in the microfluidic chips. Results showed the weakly alkaline condition (pH = 7.5), microfluidic chips with < 10 μm gaps, and > 100 mL/min total flow rate enhance CO2 absorption. At those conditions, the microfluidic device prepared 30 nm-sized nano-CaCO3 abundantly. Further, the CFD simulation proved the necessity to select the appropriate ratio of Ca(OH)2 solution and CO2-rich water to obtain nano-CaCO3 with stable particle size. CFD also informed that increasing the length of the inlet and outlet of the reaction chamber and changing the chip shape can effectively improve CaCO3 production.

Harnessing dimethyl ether and methyl formate fuels for direct electrochemical energy conversion

In this work, the oxidation of a mixture of dimethyl ether (DME) and methyl formate (MF) was studied in both an aqueous electrochemical cell and a vapor-fed polymer electrolyte membrane fuel cell (PEMFC) utilizing a multi-metallic alloy catalyst, Pt3Pd3Sn2/C, discovered earlier by us. The current obtained during the bulk oxidation of a DME-saturated 1 M MF was higher than the summation of the currents provided by the two fuels separately, suggesting the cooperative effect of mixing these fuels. A significant increase in the anodic charge was realized during oxidative stripping of a pre-adsorbed DME + MF mixture as compared to DME or MF individually. This is ascribed to greater utilization of specific catalytic sites on account of the relatively lower adsorption energy of the dual- molecules than of the sum of the individual molecules as confirmed by the density functional theory (DFT) calculations. Fuel cell polarization was also conducted using a Pt3Pd3Sn2/C (anode) and Pt/C (cathode) catalysts-coated membrane (CCM). The enhanced surface coverage and active site utilization resulted in providing a higher peak power density by the DME + MF mixture-fed fuel cell (123 mW cm−2 at 0. 45 V) than with DME (84 mW cm−2 at 0.35 V) or MF (28 mW cm−2 at 0.2 V) at the same total anode hydrocarbon flow rate, temperature, and ambient pressure.

Estimating vehicular emission factors and vehicle-induced turbulence: Application of an air quality sensor array for continuous multipoint monitoring in a tunnel

In this study, air quality monitoring nodes (equipped with pollutants (NO, NO2, CO, and PM2.5), temperature, and humidity sensors) were deployed at seven locations inside a road tunnel for continuous multipoint monitoring of traffic emissions. At the same time, in-tunnel turbulence was measured with a 3D-sonic anemometer in the middle of the tunnel to estimate vehicle-induced turbulence (VIT). The emission factors (EFs) of all pollutants estimated from conventional two-point measurements varied significantly among arbitrarily chosen pairs of measurement locations (with a range of 53–193% compared to the mean value). These findings suggest the need for multipoint monitoring for more generalizable EF estimates. Our results indicate that installing a sensor array in a tunnel could enable long-term continuous multipoint monitoring of traffic-related pollutants with limited resources. The EF estimates obtained in this study were higher (∼7 times) than those calculated from an emission inventory based on actual traffic data, particularly for CO and wintertime NOX. One possible explanation for this inconsistency is an underestimation of high emitters in the emission inventory. We also estimated VIT as a function of the total traffic flow rate and the fraction of heavy-duty diesel vehicles in a fleet. We expect our results to be used as input data for local and regional air quality models, which can improve the model's performance. We also expect that long-term continuous monitoring of air pollutants in tunnels with multiple sensor nodes will aid evaluations of the effectiveness of air pollution reduction policies by tracking changes in traffic emissions.