Dm3 Min Research Articles

Assessing the addition of hydrogen and oxygen into the engine's intake air on selected vehicle features

Road transport has a significant effect on air pollution. Therefore, the article focuses on the impact of addition of “oxyhydrogen”, known as HHO, on selected vehicle features. These features, on which this study is focused, include the engine power and torque, composition of the exhaust gases and fuel consumption. There was also an impact of HHO on the value of pre-ignition as well as engine cleaning observed. HHO has been obtained from the generator designed and constructed for the purposes of this article. The measurements were performed under conditions of taking electric energy needed for HHO operation from the vehicle used in the measurements and also from the other source. The measurements were performed with vehicles of different kilometres driven, different technical conditions and different fuels and they were conducted under laboratory conditions to ensure a higher accuracy of the results. The results have shown a low impact of HHO addition of 2 dm3 min−1 on concentration of particular components of the exhaust gases. With HHO added, it was measured a mild decrease in the engine power and torque. Taking electric energy needed for HHO operation from the vehicle used in the measurement has evinced more considerably than addition of HHO into the engine.

Water and energy savings from greywater reuse: a modelling scheme using disaggregated consumption data

Municipal drinking water supplies are under great stress globally, and one way to mitigate the problems is the reutilization of wastewater in various settings. In this paper, a greywater reuse scheme and the impact of system design and configuration on water and energy savings are investigated. The objective of the paper was to investigate the impact of hydraulic design and performance of a greywater treatment and reuse system on water and energy savings. A simulation model was created based on real, disaggregated water consumption data that predicts the reuse potential. Three scenarios were investigated; (1) greywater collection from the bathroom and reuse for toilet flushing, (2) greywater collection from bathroom sinks and showers, and reuse as hot water for sinks and showers, and (3) a combination of (1) and (2) where greywater collection from bathroom sinks and showers is used for toilet flushing, sinks and shower. The results indicate hot water reductions between 55.6 and 58.2%, while cold water reductions ranged from 5.8 to 30.6%. Reductions in energy for producing hot water between 43.5 and 46.8% were observed. Recommendations per connected user for hydraulic design ranged from 0.033 to 0.1 dm3 min−1, 3 dm3, and 0.7–10 dm3 for treatment capacity, collection and holding tank volume.

Evaluation of a decaying swirling flow electrochemical reactor for the manufacture of colloidal sulphur by reduction of sulphur dioxide

The behaviour of an electrochemical reactor with decaying swirling flow is analysed for the production of colloidal sulphur using sulphur dioxide from synthetic effluents as raw material. The experiments were done under potentiostatic control with single- and two-phase flow. The best results were obtained at a cathodic potential of −0.7 V, against a saturated calomel electrode. Thus, in a single-phase experiment at a volumetric flow rate of 8 dm3 min−1 and 1 g dm−3 SO2 in 0.5 mol dm−3 H2SO4 as a supporting electrolyte, the current efficiency was 64% with a specific energy consumption of 22.7 kW h kg−1 and a space time yield of 5.6 kg m−3 h−1, achieving a total removal of sulphur dioxide after 15 min of operation. For sulphur dioxide concentrations lower than 2.5 g dm−3 the cathode surface remained free of a sulphur layer due to the impingement action of the swirling flow. Similar results were obtained under a two-phase flow of 5% SO2 in nitrogen. In this case, the sulphur particles presented mainly spheroidal shape with an average size of 2.8 μm being of high purity. The comparison with other types of electrochemical reactors concludes that the equipment with swirling flow represents the best option.

The characterization of a packed bed plasma reactor for ozone generation

A packed bed plasma reactor (PBPR) was designed, characterized and optimized for ozone generation from oxygen and air. The effects of reactor arrangement, feed gas flow rate, coolant temperature, input power and dielectric material on ozone generation were investigated. The highest ozone concentration of 152 g m−3 was obtained using 2.0 mm borosilicate glass beads and a 0.06 dm3 min−1 oxygen feed at 5 °C, whilst the highest ozone yield efficiency was 209 g kW−1 h−1 at an oxygen feed rate of 20 dm3 min−1. The highest ozone concentration produced from air was 15.6 g m−3 at a flow rate of 0.06 dm3 min−1 with 2.0 mm 3 A molecular sieves beads (MS) beads as the dielectric. It was found that the effect of the dielectric on ozone generation affected significantly by the feed gas composition and flow rate. In addition, ozone production affected significantly by the number of dielectric layers in contact with the HV electrodes, thickness of packing and reactor arrangement. Different NOx by-products were formed along with ozone when the PBPR was fed with air depending on the coolant temperature and feed gas flow rate.

Gas-lift circulation of a liquid between two inter-connected bubble columns

A pneumatically-mixed novel configuration of two inter-connected bubble column reactors is reported using air-water to demonstrate the device, enabling circulation of a liquid between the columns solely by a gas-lift mechanism. The new reactor may be used for circulating a high temperature/corrosive liquid between the columns, enabling the cyclical processing of a liquid medium with two different gaseous reactants. The effects of superficial gas velocity, unaerated liquid height in the columns and the diameter of aeration nozzles are discussed with reference to the gas holdup in, and rate of liquid circulation between, the two columns, together with the energetics of circulation. The height of the gas-free liquid in the reactor was found to influence the liquid circulation velocity positively, but the effect of aeration nozzles diameter was marginal. The lowest and highest measured flow rates of circulating water between the columns were 0.7 dm3 min−1 and 4.2 dm3 min−1, respectively.

Removal and recovery of a cationic surfactant from its aqueous solution by foam fractionation

Extensive use of the surfactants helps the development of many consumer products, but it contaminates water in many cases. Thus, the removal and recovery of these surfactants has become essential. In this study, a cationic surfactant (i.e., cetyltrimethylammonium bromide) was recovered from its aqueous solution by employing the foam fractionation method in batch mode in a cylindrical column. The surfactant concentration was five times its critical micellar concentration (i.e., 1822 mg dm–3). The effects of three salts (i.e., NaCl, CaCl2, and Na2SO4) and airflow rate on the surfactant recovery were studied. The salt concentration was varied from 10 to 100 mol m−3, and the airflow rate was varied from 0.4 to 1.6 dm3 min−1. About 60 % of the surfactant was recovered from the top of the column in the form of a semi-solid paste. The foam volume and surfactant recovery were reduced by the addition of salt. The stability of the foam played a very important role in surfactant recovery. The recovery of water was excellent.

NO2 and HONO concentrations measured with filter pack sampling and high HONO/NO2 ratio in Ho Chi Minh city, Vietnam

Nitrogen dioxide and nitrous acid (HONO) in the atmosphere were simultaneously measured with a filter pack (FP) method in Ho Chi Minh City, Vietnam (HCM), in 2017 and 2018. To collect NO2 effectively, the absorption performance of NO2 by the FP method with a triethanolamine (TEA)-impregnated filter was improved. After HNO3 and HONO in the sample air were collected by NaCl and Na2CO3 impregnated filters, respectively, at 2.0 or 4.0 dm3 min−1, NO2 was collected. The air flow was divided into two lines after the HNO3 and HONO filter pack, and one line was used for collecting NO2. With a 0.1 dm3 min−1 flow rate and 20 wt% TEA in the impregnating solution, the collection efficiency of NO2 was almost 100%. The present method was applied for the measurement of HONO and NO2 in HCM in August 2017 and 2018. The average concentrations (29–48 h average) of NO2 and HONO were 17.1 ± 5.7 ppb (average ± 1 standard deviation) and 2.2 ± 0.6 ppb, respectively. The average HONO/NO2 ratio of 13.4 ± 3.5% was significantly higher by a considerable margin than reported values in the literature.

Effects of thawed depth on the sediment transport capacity by melt water on partially thawed black soil slope

AbstractThis study proposed an apparatus for measuring the sediment transport capacity, which is an important parameter for rill erosion prediction and modeling. Laboratory experiments were conducted to measure the sediment transport capacity of partially thawed black soil slope under different hydraulic conditions and thawed depths (five slope gradients of 5°, 10°, 15°, 20°, and 25°; three flow discharges of 1, 2, and 4 dm3 min−1; and four thawed depths of 1, 2, 5, and 10 cm). The effect of thawed depth on sediment transport capacity was quantified with experimental data under different slope gradients and flow discharges. A quadratic model was used to relate sediment transport capacity to thawed depth, slope gradient, and flow discharge, and its key factors that influenced sediment transport capacity were determined by using stepwise regression. Results showed that sediment transport capacity decreased with the increase of thawed depth from 1 to 5 cm, but it tended to be steady when the thawed depth was greater than 5 cm. Model‐fitting results showed that sediment transport capacity was positively correlated with slope gradient and flow discharge but negatively correlated with thawed depth. The proposed method and experimental device solved the difficulties of insufficient sediment supply on the measurement of sediment transport capability, and it can be used to measure the sediment transport capacity of concentrated water flow under different conditions of slope gradient, thawed depth, and flow discharge. The method is helpful to the research of erosion process of partially thawed soil under concentrated water.

Optimization of the catalyst loading for the direct borohydride fuel cell

Direct borohydride fuel cells (DBFC) are considered as attractive energy suppliers because of their high electrochemical activity, open circuit potential, energy storage capacity, and power performance at ambient temperature. For the successful commercialization of the DBFCs, cost effective and high performance cells should be produced. In this study, the analysis and optimization of the DBFC operation conditions are carried out with Design Expert software central composite tool. Power density is chosen as a response (dependent) parameter and cell temperature, borohydride concentration, anode and cathode flow rates and catalyst loading are chosen as independent parameters. Based on ANOVA (analysis of variance) analyses, the maximum power density of 108.5 mW cm−2 is obtained at cell temperature of 79.8 °C, borohydride concentration of 1.5 M, anode flow rate of 5 cm3 min−1, cathode flow rate of 0.1 dm3 min−1and PtRu/C catalyst loading of 0.7 mg cm−2.

Development and application of a simultaneous measurement method for gaseous ammonia and particulate ammonium in ambient air

ABSTRACTAmmonia gas is one of the precursors contributing to the formation of secondary particulate ammonium via reactions with atmospheric acids, such as sulfuric and/or nitric acids, which are present in ambient air. In this study, a new instrument that is suitable for measuring ammonia gas and fine particulate ammonium (PM2.5 NH4+) concentrations simultaneously under ambient conditions was developed. A wetted frit sampler was connected in the back of a counter-current flow tube (CCFT) sampler, and the NH3 gas and PM2.5 NH4+ samples were collected by CCFT and wetted frit samplers, respectively. An air sample was drawn through the samplers at a flow rate of 1.0 dm3 min−1 and an absorption water flow rate of 120 mm3 min−1. Then, the ammonium that formed in the absorption solution was detected by the indophenol method using a continuous flow analysis system. The estimated detection limits were 43 and 49 ng m−3 for ammonia gas and PM2.5 NH4+, respectively. Notably, the ammonia gas was collected on the CCFT ...

The influence of different agitation techniques on the adsorption kinetics of 4-chlorophenol on granular activated carbon

The influence of different agitation techniques on the adsorption of organic compounds, represented by 4-chlorophenol, onto granular activated carbon was investigated. The effect of the flask type and the type of agitator, including a laboratory shaker, mechanical agitator, magnetic stirrer as well as mixing with gas bubbles, was studied. The results of adsorption kinetics demonstrate that the adsorption process of 4-chlorophenol on the activated carbon follows a pseudo-second order kinetic model closely. The adsorption equilibrium was reached faster in the Erlenmeyer flask than in the round-bottomed flask. At the same agitation speed (200 rpm), the better adsorption rate and adsorption efficiency were observed using the mechanical and magnetic stirrers than the laboratory shaker. At the gas flow rate of 1.5 dm3 min−1, the mixing with the air or nitrogen bubbles was comparable with the agitation when using mechanical and magnetic stirrers at 200 rpm. The effect of the agitation speed on the adsorption of the 4-chlorophenol by the activated carbon was also tested. The kinetic experiments were carried out at 100, 200, 300 and 500 rpm and it was found that the adsorption rate increases with the increase in the agitation speed. As the stirring rate increased from 100 to 500 rpm, the adsorption rate constants increased from 0.577 to 1.264 g mmol−1 h−1 (mechanical agitator) and from 0.560 to 1.231 g mmol−1 h−1 (magnetic stirrer), respectively. The experimental results demonstrate that the agitation affects the adsorption kinetics significantly as well as the adsorption equilibrium of the organic compounds on the activated carbon, and should be taken into account in such studies.

A Multi‐Function Compact Micro‐Channel Reactor Coated with Sulphur Tolerant Catalyst for LPG Steam Reforming

AbstractHydrogen fuelled polymer electrolyte fuel cells (PEFC) offer clear environmental benefits. Lack of viable hydrogen infrastructure in the near future means that a key issue is availability of hydrogen at the point of use. Liquefied petroleum gas (LPG) offers advantages as a fuel over other hydrocarbons because there is already an infrastructure in place for remote areas. Hydrogen supply via steam reforming of LPG is therefore a feasible avenue of achieving the environmental benefits. Commercial grade LPG unavoidably contain sulphur as an odorant, the sulphur needs to be removed from the fuel stream before it reaches the reformer catalyst and fuel cell. Utilizing sulphur tolerant catalysts in the reformer leads to a simpler fuel processor design. Thermal management and reforming efficiency has been a challenge for the sulphur tolerant catalysts. In this paper, a multi‐function compact micro‐channel reactor designed for hydrocarbon steam reforming was evaluated for use with LPG. A sulphur tolerant catalyst was wash‐coated on to the reforming layers. The reformer was tested over a wide range of reactor temperatures, steam to carbon ratios and fuel flow rates. Over 60% of H2 composition can be achieved at high reforming temperatures with a LPG supply rate of 0.75 dm3 min−1 (STP) and a S/C ratio of 4.

Investigation of Carbon Supported Nanostructured PtAu Alloy as Electrocatalyst for Direct Borohydride Fuel Cell

AbstractCarbon supported bimetallic PtAu electrocatalysts for sodium borohydride electrooxidation are prepared by a modified citrate stabilized NaBH4 reduction process at different pH and temperature values. The physical properties of the materials are characterized by X‐ray diffraction spectroscopy, energy dispersive spectrometry, X‐ray photoelectron spectroscopy and transmission electron microscopy. Nano sized electrocatalysts have narrow size distributions and are uniformly dispersed on the surface of carbon support. Electrochemical performances of catalysts for sodium borohydride electrooxidation are tested with 25 cm2 single fuel cell. The highest performance is obtained at a peak power density of 161 mW cm−2 with 20 wt. % PtAu/C catalyst of 7.03 nm. Impact of the fuel cell operation parameters including concentration of NaBH4, flow rates of oxidant and fuel, and fuel cell operation temperature are investigated. The best operation parameters are obtained at 1 M NaBH4 concentration, 3 cm3 min−1 NaBH4 flow rate, 0.2 dm3 min−1 oxygen flow rate and 65 °C fuel cell temperature.

Oxygen separating membrane manufactured from Ba0.5Sr0.5Co0.8Fe0.2O3−δ perovskite-like material

The dense thin membrane for oxygen separation was manufactured from Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF) mixed oxide with perovskite-like structure prepared by the solid-state method. Properties of both powder and granulate (chemical and phase compositions, the specific surface area and the porosity) as well as sintered material (the apparent density, the apparent porosity, the water absorbability, the chemical composition, the crystallographic structure and microstructure), that affect the process of ion oxygen permeation through membrane, were determined. Parameters influencing on usable properties of membranes viz., the bending strength and the coefficient of thermal expansion were assessed as well. Effect of the sintering temperature on membrane structure was evaluated. The elaborated fabrication procedure enables one to manufacture membrane, in which microstructure is characterized by the presence of big grains as well as decreased concentration of grain boundaries. Measurements of the oxygen permeation through BSCF membrane revealed that the highest oxygen flux reaching 2.6 cm3 O2/(cm2 min) was obtained at 950°C under air and helium flows equal to 1 dm3 min−1.

The effect of fuel type on the performance of a direct carbon fuel cell with molten alkaline electrolyte

In the paper the behavior of various carbon-rich materials used as fuels for the direct carbon fuel cell (DCFC) with molten hydroxide electrolyte is presented. For the current research various carbonaceous fuels (e.g., different biochars, hard coal, graphite, carbon black) were tested. The electrolyte was the binary eutectic mixture of sodium and lithium hydroxides (90 mol.% NaOH – 10 mol.% LiOH). The fuel cell was operated at 723 K and cathode air flow rate of 0.5 dm3 min−1. The maximum power densities were achieved for raw coal and commercial biochar and made up 38.6 mW cm−2 and 32.8 mW cm−2, respectively.

TiO2-assisted photocatalytic degradation of diclofenac, metoprolol, estrone and chloramphenicol as endocrine disruptors in water

The photocatalytic oxidation of diclofenac, metoprolol, estrone and chloramphenicol was tested in the tube reactor using different commercially available TiO2. The photocatalysts were characterized using BET, XRD and SEM. The studied photocatalysts differed in SBET, pore volume and rutile presence. It was observed that generally anatase TiO2 possessed the highest activity in the photocatalytic oxidation of diclofenac, chloramphenicol and estrone. The presence of rutile enhanced the photooxidation of metoprolol. In case of the other pollutants, however, rutile diminished the photooxidation efficiency. The most effective in the reduction of the COD parameter of treated water was anatase with 21 nm crystals. The photooxidation of all studied pollutants can be described by the pseudo-first order kinetics with the values ranging from 0.46 × 10−2 min−1 in case of estrone removal over Tytanpol (Z.A. Police, Poland) to 1.87 × 10−2 min−1 for the removal of chloramphenicol over TiO2 21 nm (Sigma-Aldrich). The highest initial reaction rates were obtained for metoprolol removal over TiO2 21 nm (Sigma-Aldrich) 1.9 × 10−6 mol dm3 min−1 being three times higher than that determined for estrone photocatalytic oxidation over TiO2 (Sigma-Aldrich).

Surface modified annular wet denuder for the collection of water-soluble trace gases

An annular wet denuder with both annular surfaces functioning as a sink for gaseous molecules is described. A gas absorbing solution was continuously flowed down the stainless-steel inner tube exterior and the outer tube interior gas collection surfaces of the denuder. In order to enhance the gas collection efficiency, the gas collection surfaces were modified with a Nylon monofilament and a perfluoroalkoxy alkane screen mesh cloth. The collection efficiency was increased by coiling the monofilament around the inner tube exterior, and by fixing the screen mesh cloth on the outer tube interior (e.g. 1.67 ± 0.06 and 1.77 ± 0.01 times at a gas absorbing solution flow rate of 0.30 cm3 min−1 tube−1, respectively). At a sampling flow rate of 1.0 dm3 min−1, 97.7 ± 0.53% of the trace gas was collected with the surface modified annular wet denuder. The response speeds of the analytical signal change (10% → 90% and 90% → 10%) were 5.0 ± 0.9 min and 4.4 ± 0.2 min, respectively. Quantitative collection of water-soluble trace gas and reasonably rapid response time were achieved with the developed device.

Electrochemical treatment of water containing chlorides under non-ideal flow conditions with BDD anodes

In this work a undivided parallel plate cell equipped with boron doped diamond (BDD) anode was tested as electrochemical reactor for disinfection of water. Two configurations were adopted: a single pass configuration (SPC) and a recirculated configuration (RC) in which also a reservoir was inserted in the hydraulic circuit. In both the experimental configurations the system worked in continuous mode with a flow rate ranging from 0.05 to 0.42 dm3 min−1; in the RC the recirculating flow rate ranged from 0.45 to 6 dm3 min−1. Thermostated (25 °C) galvanostatic electrolyses were carried out with aqueous solutions containing 100 mg dm−3 of chloride ions: values of current density from 2.5 to 5.0 mA cm−2 were used. Steady state data revealed that active chlorine and chlorate ions were the main oxidation products. Particular attention was paid to the hydrodynamics both for SPC and RC: pulse-response curves were experimentally obtained with an inert tracer, and the behaviour of the system was interpreted by models based on a combination of ideal flow reactors, bypass flow elements, and dead zones. The hydrodynamic models were utilized to predict the outlet concentration of the electrolysis products. A good agreement between model predicted and experimental data was obtained for a wide range of experimental conditions. Preliminary disinfection tests were then performed using Escherichia coli as model microorganism. Results were discussed in terms of both disinfection efficiency and by-products formation.

フッ素系樹脂薄膜の大気圧プラズマ処理と表面微細構造の形成メカニズム

This paper describes fabrication of a nano-textured surface on a fluorocarbon thin film using atmospheric-pressure microplasma (μ-AP; NU-Eco Engineering). Results show that a textured surface with vertical bumps of several tens of nanometers can be fabricated on a fluorocarbon 1.0-μm-thick thin film coated onto a steel substrate when argon gas is supplied with a 4.0 dm3 min−1 flow rate. The plasma-treated surface roughness decreased concomitantly with increased processing distance. Moreover, the horizontal intervals of the bumps are influenced by annealing treatment conditions.From measurement results obtained using atomic force microscopy (AFM), results show that non-uniformity of fluorocarbon polymer orientation, which is detectable as fluctuations in friction force, in the coating film before the plasma treatment is correlated with the number density of bumps fabricated by the plasma treatment, indicating that well-oriented fluorocarbon polymers are difficult to etch using plasma treatment. Furthermore, chemical bond components of C1s were analyzed using X-ray photoelectron spectroscopy (XPS) before and after treatment. Results show that C-H and C-C bonds are fewer after the plasma treatment, but C-O and C=O bonds are more numerous. The oil contact angles changed concomitantly with the change in surface morphology and chemical bond components according to the plasma treatment.

Removal of Ni(II) Using Cation Exchange Resins in Packed Bed Column: Prediction of Breakthrough Curves

AbstractSorptive removal of Ni(II) from electroplating rinse wastewaters by cation exchange resin Dueolite C 20 was investigated at the temperature of 30°C under dynamic conditions in a packed bed. The effects of sorbent bed length 0.1–0.2 m, fixed flow rate 6 dm3 min−1, and the initial rinse water concentration (C0) 53.1 mg L−1 on the sorption characteristics of Dueolite C 20 were investigated at an influent pH of 6.5. More than 94.5% of Ni(II) was removed in the column experiments. The column performance was improved with increasing bed height and decreasing the flow rate. The Thomas, Yoon–Nelson, Clark, and Wolborska models were applied to the experimental data to represent the breakthrough curves and determine the characteristic design parameters of the column. The sorption performance of the Ni(II) ions through columns could be well described by the Thomas, Yoon–Nelson, and Wolborska models at effluent‐to‐influent concentration ratios (C/C0) >0.03 and <0.99. Among the all models, the Clark model showed the least average percentage time deviation. The sorptive capacity of electroplating rinse water using Ni(II) was found to be 45.98 mg g−1.