Search Results (25)

Diesel engines are known for their excellent efficiency and are therefore used in a variety of applications. However, they are also one of the main sources of hazardous emissions such as nitrogen oxides (NO_x) and smoke. Water-in-Diesel Emulsion (WiDE) is an alternative fuel that can possibly reduce some of the pollutant emissions without compromising engine performance. The surfactant formulation for WiDE usually follows the one used in water-in-oil (w/o) emulsions, where low hydrophilic–lipophilic balance (HLB) emulsifiers are preferred for better solubility in the diesel phase and stabilization at storage temperatures. However, by using a hydrophilic blend with a non-ionic surfactant, it is possible to develop an optimized formulation at higher fuel temperatures, which occur during an engine’s operating condition, achieving possibly higher benefits. Across the different speeds, the results for the emulsion show 7.57% mean improvement in specific fuel consumption (SFC), 19.14% mean improvement in thermal efficiency (TE), 5.54% mean reduction in carbon dioxide (CO₂), 20.50% mean reduction in nitric oxide (NO) and 75.19% mean reduction in smoke levels. However, carbon monoxide (CO) and hydrocarbons (HC) emissions were higher, with a mean increase of 81.09% and 93.83%, respectively. Full article

Biosurfactants are surface-active molecules, produced by several microorganisms, that possess unique properties such as low toxicity and biodegradability. Their application in various industries depends on their purity and their specific properties, such as emulsification and stability. Therefore, this study focuses on the production of biosurfactant from Bacillus atrophaeus in an air-lift bioreactor. It analyzes the effects of agitation rate and temperature on biosurfactant production, as well as the concurrent separation process using a foam fractionation column. Moreover, the ability of the produced biosurfactant to form emulsions in water with several substrates (vegetables oils, hydrocarbons, and fossil fuels) was determined, and the stability of the soybean oil–water emulsion (used as an example) at different temperatures and pH values was verified. The biosurfactant produced, tentatively identified as iturin, was only detected in the coalescent liquid after passing through the foam fractionation column, demonstrating the complete separation of the biosurfactant. The best operational conditions for production and separation were an air flow of 1.00 vvm and a temperature of 34 °C (emulsifier index (EI₂₄₎ = 66.9%, and productivity (Pp) = 967.5% mL h⁻¹). Vegetable oils, hydrocarbons, and fossil fuels were emulsified in water, highlighting the soybean oil, whose emulsion oil–water had the highest ES (3333.3 min) at a temperature of 50 °C and a pH value of 9.0. Full article

Emulsions that mix two or more immiscible phases are broadly applied in pharmaceutics, chemistry, and industries. The phase inversion temperature (PIT) method is an emulsifying approach to preparing an emulsion with low energy consumption and cheap equipment. The effects of surfactant characteristics and processes of cooling or heating on the fuel properties of emulsions composed of silicone oil by the emulsifying method, such as mean droplet sizes of the de-ionized water phase, were considered herein. The application of the silicone oil emulsion as engine fuel was first evaluated. The results show that the emulsions added with the polyol surfactant mixture appeared to have a larger mean water-droplet size, a larger number of dispersed water droplets, a wider range of dispersed-water sizes, and lower kinematic viscosity than those with Brij 30 surfactant. Increasing the surfactant concentration of either Tween 20 mixed with Span 80 or Brij 30 surfactant increased kinematic viscosity and the number of dispersed droplets while decreasing mean droplet sizes. After being subjected to fast heating and then fast cooling, the silicone oil emulsion appeared to form many smaller dispersed droplets than those being proceeded with slow cooling. The emulsion of silicone oil was found to have adequate engine fuel properties. Full article

The effects of emulsification variables, such as surfactant type and heating/cooling emulsion processes, on the emulsification characteristics of silicone oil’s emulsions prepared by the phase inversion temperature method were investigated in this study. The water-in-oil (W/O) emulsions have been widely applied to enhance burning efficiency and reduce both pollutant emissions and fuel consumption. The silicone oil was emulsified with de-ionized water with the assistance of nonionic surfactants to form oil-in-water (O/W) emulsions. The hydrophilic–lipophilic balance (HLB) value of the Span 80 and Tween 20 surfactant mixture was set equal to 10 based on their weight proportions and the respective HLB values of the two surfactants. The experimental results show that the emulsions with the Span 80/Tween 20 surfactant mixture appeared to have a higher phase inversion temperature and a larger electrical conductance. On the other hand, it has a lower emulsification stability and a narrower range of phase inversion temperature than the emulsions prepared with a Brij 30 surfactant (polyoxyethylene (4) lauryl ether). The increase in surfactant concentration from 1 wt.% to 10 wt.% decreased the electrical conductance and phase inversion temperature while increasing the suspensibility and absorbance value for the emulsions prepared with either Span 80/Tween 20 mixture or Brij 30. Full article

In this work, membranes were synthesized by depositing fluoropolymer coatings onto metal meshes using the hot wire chemical vapor deposition (HW CVD) method. By changing the deposition parameters, membranes with different wetting angles were obtained, with water contact angles for different membranes over a range from 130° ± 5° to 170° ± 2° and a constant oil contact angle of about 80° ± 2°. These membranes were used for the separation of an oil–water emulsion in a simple filtration test. The main parameters affecting the separation efficiency and the optimal separation mode were determined. The results reveal the effectiveness of the use of the membranes for the separation of emulsions of water and commercial crude oil, with separation efficiency values that can reach over 99%. The membranes are most efficient when separating emulsions with a water concentration of less than 5%. The pore size of the membrane significantly affects the rate and efficiency of separation. Pore sizes in the range from 40 to 200 µm are investigated. The smaller the pore size of the membranes, the higher the separation efficiency. The work is of great economic and practical importance for improving the efficiency of the membrane separation of oil–water emulsions. It lays the foundation for future research on the use of hydrophobic membranes for the separation of various emulsions of water and oil products (diesel fuel, gasoline, kerosene, etc.). Full article

This paper presents findings from an experimental study investigating the secondary atomization of liquid fuel droplets widely used in the heat and power industry exemplified by fuel oil and environmentally promising fuel oil/water emulsion. The scientific novelty comes from the comparative analysis of the critical conditions and integral characteristics of the secondary atomization of the liquid and composite fuels with the greatest potential for power plants. Here, we used two fuel atomization schemes: droplet–droplet collisions in a gas and droplets impinging on a heated solid wall. The temperature of the liquids under study was 80 °C. The velocities before collision ranged from 0.1 m/s to 7 m/s, while the initial droplet sizes varied from 0.3 mm to 2.7 mm. A copper substrate served as a solid wall; its temperature was varied from 20 °C to 300 °C. The main characteristics of droplet interaction were recorded by a high-speed camera. Regime maps were constructed using the experimental findings. It was established that the critical Weber number was several times lower when water and fuel oil droplets collided than during the collision of fuel oil droplets with 10 vol% of water. The secondary atomization of fuel oil/water emulsion droplets by their impingement on a heated solid wall was found to reduce the typical sizes of liquid fragments by a factor of 40–50. As shown in the paper, even highly viscous fuels can be effectively sprayed using primary and secondary droplet atomization schemes. It was established that the optimal temperature of the fuel oil to be supplied to the droplet collision zone is 80 °C, while the optimal substrate temperature for the atomization of fuel oil/water emulsion droplets approximates 300 °C. Full article

The main characteristics of ignition and combustion of fuel droplets (organic coal-water fuel, oil emulsion, and oil in the usual state) placed on the heated surfaces of structural steel (DIN standard grade X16CrNi25-20) were experimentally determined under conditions corresponding to the start-up and nominal operation of power-generating equipment. It was shown that due to the application of texture on the steel surfaces, it is possible to change the ignition and combustion characteristics of fuel droplets. A graphic-analytical method was developed to predict the dimensions of textures in the form of microchannels using laser technology for processing metal surfaces. It was found that the texture configuration in the form of microchannels formed by nanosecond laser radiation on steel surfaces makes it possible to significantly increase the surface resistance to adhesion of combustion products of liquid and slurry fuels. Full article

Phase-change materials (PCMs) attract much attention with regard to their capability of mitigating fossil fuel-based heating in in-building applications, due to the responsive accumulation and release of thermal energy as a latent heat of reversible phase transitions. Organic PCMs possess high latent heat storage capacity and thermal reliability. However, bare PCMs suffer from leakages in the liquid form. Here, we demonstrate a reliable approach to improve the shape stability of organic PCM n-octadecane by encapsulation via interfacial polymerization at an oil/water interface of Pickering emulsion. Cellulose nanocrystals are employed as emulsion stabilizers and branched oligo-polyol with high functionality to crosslink the polyurethane shell in reaction with polyisocyanate dissolved in the oil core. This gives rise to a rigid polyurethane structure with a high density of urethane groups. The formation of a polyurethane shell and successful encapsulation of n-octadecane is confirmed by FTIR spectroscopy, XRD analysis, and fluorescent confocal microscopy. Electron microscopy reveals the formation of non-aggregated capsules with an average size of 18.6 µm and a smooth uniform shell with the thickness of 450 nm. The capsules demonstrate a latent heat storage capacity of 79 J/g, while the encapsulation of n-octadecane greatly improves its shape and thermal stability compared with bulk paraffin. Full article

This paper presents experimental findings on heat and mass transfer, phase transitions, and chemical reactions during the interaction of CO₂ hydrate in powder granules and tablets with burning liquid fuels and oil. The experiments involved CO₂ hydrate tablets and spheres made of pressed granules. The fire containment and suppression times were established experimentally. Using the gas analysis data, we studied the effects of the mitigation of anthropogenic emissions from the combustion of liquids and their suppression by gas hydrates. We also compared the performance of water aerosol, foaming agent emulsion, snow, ice, and CO₂ hydrate samples as laboratory-scale fire suppressants. The paper further describes the numerical modeling of the CO₂ hydrate dissociation during liquid fuel combustion. The rapid carbon dioxide release is shown to prevent the oxidizer from the combustion zone. The suppression of a flame using powder with a granule size of 3 mm requires 20-times less carbon dioxide hydrate than in the case of pressed tablets. Effective conditions are identified for using CO₂ hydrates to extinguish fires involving flammable liquids and most common fuels. Full article

Alternative marine fuels are needed to help reduce the exhaust emissions of ships. In this study, we performed an analysis to verify the potential applicability of a fuel based on Bunker-C oil, a low-grade marine heavy oil, as a novel alternative marine fuel. Bunker-C oil and water were mixed in the presence of a 0.8–1.2% emulsifier in four steps from 0% to 25% to produce a special type of emulsified fuel oil. Confocal microscopy images of samples after stabilization for approximately three days at room temperature showed no variation in the pattern at the 0% condition with no water, but a relatively homogenous mixed state of water droplets was found across all domains at the 5–25% conditions. The open-source software Image-J indicated the extraction of 166, 3438, and 5636 water droplets with mean diameters of 1.57, 1.79, and 2.08 μm, as well as maximum diameters of 7.31, 21.41, and 25.91 μm, at the 5%, 15%, and 25% conditions, respectively. For all three conditions, the mean particle diameter was approximately 2 μm, below the 20 μm reported in previous studies, with uniform distributions. This suggests that the mixed state was adequately homogenous. Full article

The aim of this work is the combustion of emulsions in two internal combustion diesel engines, instead of residual fuel oil, to reduce pollutant emissions into the atmosphere and fuel consumption for a cleaner energy transition. A methodology was designed that include the planification and implementation of several experiments in a thermoelectric power plant in Madeira Island, that is part of an isolated electricity production system. In the first place, the planification of experiences was developed and the reference points were created. In this case study, three different operating regimes at the nominal speed of 500 rpm were studied: 7.5 MW, 8.5 MW and 9.5 MW, with a gradual increase of the incorporation of water into the emulsions. A comparative analysis of the potential emulsions in diesel engines, instead of fuel oil, were carried out and two process solutions were created in the 8.5 MW regime with 15% v/v of water and 18% v/v of water. The impact on process parameters and the savings obtained were measured. The best result obtained was the reduction of 56.5% of CO, 96.7% of NO₂ and 4.2% of NOx emissions. The specific fuel consumption savings obtained were 2.7%. In conclusion, the experiments and research developed contributed to a more in-depth knowledge about the potential of emulsions in combustion systems; pollutant emissions were reduced; and we designed a new operation regime for the internal combustion engine that are part of an isolated electricity production system. Full article

To implement a circular economy policy, methods of using waste products as a starting point for other technologies are constantly researched. One of the waste products that should be disposed of after use is waste engine oil (WEO). Despite the permanent introduction of the electrification of cars, the number of combustion vehicles (and, thus, the production of WEO) is constantly increasing. For these reasons, the reuse of WEOs is extremely important; e.g., to use these oils for energy purposes. One of the potential uses of this type of oil is as fuel for fuel cells (for direct electricity production). To lower the production costs of electrodes for fuel cells, catalysts that do not contain precious metals are being constantly sought. This work shows the research of WEO electrooxidation feasibility with Ni-Co and Cu-B catalysts. The results showed the feasibility of the electrooxidation of WEO emulsion on Ni-Co and Cu-B electrodes in an electrolyte (a water solution of sulfuric acid). Moreover, it was shown that the electrooxidation of the WEO emulsion occurred for all concentrations of WEO in the emulsion for all measurement temperatures (20–80 °C). The highest current density obtained in the measurements was 11 mA cm⁻² (at 60 °C) for the Ni-Co electrode. Full article

The application of water-fuel emulsion (WFE) in internal combustion engines enables to reduce the consumption of sulfurous fuel oils, thereby protecting the environment from emissions of sulfur and nitrogen oxides, as well revealing a great potential for the heat utilization of exhaust gases. The efficiency of utilization of exhaust gas heat in exhaust boilers (EGB) depends on their temperature at the outlet of EGB, id est. the depth of heat utilization. Exhaust gas temperature is limited by the rate of low-temperature corrosion (LTC), which reaches a level of 1.2 mm/year at the wall temperature of about 110 °C for the condensing heat exchange surfaces (HES) and reduces the reliability of the HES operation. Therefore, decreasing the corrosion rate of condensing HES at wall temperature below 110 °C to an acceptable level (about 0.2 mm/year) when undergoing WFE combustion will make it possible to reduce the exhaust gas temperature and, consequently, increase the efficiency of EGB and fuel saving during the operation of the ship power plant. The aim of the research is to assess improvements to the reliability, durability and efficient operation of condensing HES in marine EGB undergoing WFE combustion in a diesel engine based on experimental studies of the LTC process. A special experimental setup was developed for investigation. The use of WFE with a decreased wall temperature of HES below 80 to 70 °C would improve the reliability of the EGB along the accepted service life, increase the lifetime of the HES metal by almost six times as well as the overhaul period, and reduce the cost of repairing condensing HES. Furthermore, due to the reducing corrosion rate under WFE combustion, the application of low-temperature condensing HES makes it possible to enhance the efficiency of deeper exhaust gas heat utilization and provide sustainable efficient operation of a diesel engine plant on the whole at a safe thermal and environmentally friendly level. Full article

Liquid fuel can be an alternative to solid fuel in non-gasified locations. The mazout for municipal-energy boiler plants is much cheaper than fuel oil. However, this relates to the problem of wastewater disposal from such a boiler plant. A proprietary system for the disposal of bottom water and other sewage-containing mazout has been developed. The solution depends on the proper preparation and burning of a water–mazout emulsion (WME). The emulsion is prepared in a specially designed and developed dosing ejector. By burning the emulsion using the developed system, an efficiency increase of 2–3% was achieved for boilers operating on the mazout fuel. Such a result was achieved due to a reduction in the excess air factor. Moreover, emissions of nitrogen oxides and carbon monoxide were reduced by 30–35% and 70–80%, respectively. In addition due to cleaning the heat-exchange surfaces obtained when working on the WME, the amount of time for productive and more efficient use of the equipment has increased. Full article

The fuel efficiency of marine diesel engine as any combustion engine falls with raising the temperature of air at the suction of its turbocharger. Therefore, cooling the engine turbocharger intake air by recovering exhaust gas heat to refrigeration capacity is a very perspective trend in enhancing the fuel efficiency of marine diesel engines. The application of water-fuel emulsion (WFE) combustion enables the reduction of a low-temperature corrosion, and, as a result, provides deeper exhaust gas heat utilization in the exhaust gas boiler (EGB) to the much lower temperature of 90–110 °C during WFE instead of 150–170 °C when combusting conventional fuel oil. This leads to the increment of the heat extracted from exhaust gas that is converted to refrigeration capacity by exhaust heat recovery chiller for cooling engine turbocharger sucked air accordingly. We experimentally investigated the corrosion processes on the condensation surfaces of EGB during WFE combustion to approve their intensity suppression and the possibility of deeper exhaust gas heat utilization. The fuel efficiency of cooling intake air at the suction of engine turbocharger with WFE combustion by exhaust heat recovery chiller was estimated along the voyage line Mariupol–Amsterdam–Mariupol. The values of available refrigeration capacity of exhaust heat recovery chiller, engine turbocharger sacked air temperature drop, and corresponding reduction in specific fuel consumption of the main low-speed diesel engine at varying actual climatic conditions on the voyage line were evaluated. Full article