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In order to improve the efficiency of the Savonius type vertical axis wind turbine, the present work analyzes an improvement based on an innovative rotor geometry. The rotor blades are inspired on an organic shape mathematically analyzed, the Fibonacci’s spiral, presented in many nature systems as well as in art. This rotor was analyzed in a wind tunnel and through a CFD model. The power coefficients at different tip speed ratios (TSR) were characterized and compared for the Savonius turbine and two versions using the Fibonacci’s spiral. One of the proposed geometries improves the performance of the Savonius type. Particularly, the optimal configuration lead to an improvement in maximum power coefficient of 14.5% in the numerical model respect to a conventional Savonius turbine and 17.6% in the experimental model.
Javier Blanco; Juan Rodriguez; Antonio Couce; Maria Lamas. Proposal of a Nature-Inspired Shape for a Vertical Axis Wind Turbine and Comparison of Its Performance with a Semicircular Blade Profile. Applied Sciences 2021, 11, 6198 .
AMA StyleJavier Blanco, Juan Rodriguez, Antonio Couce, Maria Lamas. Proposal of a Nature-Inspired Shape for a Vertical Axis Wind Turbine and Comparison of Its Performance with a Semicircular Blade Profile. Applied Sciences. 2021; 11 (13):6198.
Chicago/Turabian StyleJavier Blanco; Juan Rodriguez; Antonio Couce; Maria Lamas. 2021. "Proposal of a Nature-Inspired Shape for a Vertical Axis Wind Turbine and Comparison of Its Performance with a Semicircular Blade Profile." Applied Sciences 11, no. 13: 6198.
CO2 is the main anthropogenic greenhouse gas and its reduction plays a decisive role in reducing global climate change. As a CO2 elimination method, the present work is based on chemical absorption using aqueous ammonia as solvent. A CFD (computational fluid dynamics) model was developed to study CO2 capture in a single droplet. The objective was to identify the main mechanisms responsible for CO2 absorption, such as diffusion, solubility, convection, chemical dissociation, and evaporation. The proposed CFD model takes into consideration the fluid motion inside and outside the droplet. It was found that diffusion prevails over convection, especially for small droplets. Chemical reactions increase the absorption by up to 472.7% in comparison with physical absorption alone, and evaporation reduces the absorption up to 41.9% for the parameters studied in the present work.
M. Lamas Galdo; J. Rodriguez García; J. Rebollido Lorenzo. Numerical Model to Analyze the Physicochemical Mechanisms Involved in CO2 Absorption by an Aqueous Ammonia Droplet. International Journal of Environmental Research and Public Health 2021, 18, 4119 .
AMA StyleM. Lamas Galdo, J. Rodriguez García, J. Rebollido Lorenzo. Numerical Model to Analyze the Physicochemical Mechanisms Involved in CO2 Absorption by an Aqueous Ammonia Droplet. International Journal of Environmental Research and Public Health. 2021; 18 (8):4119.
Chicago/Turabian StyleM. Lamas Galdo; J. Rodriguez García; J. Rebollido Lorenzo. 2021. "Numerical Model to Analyze the Physicochemical Mechanisms Involved in CO2 Absorption by an Aqueous Ammonia Droplet." International Journal of Environmental Research and Public Health 18, no. 8: 4119.
Marine engines are key components in most ships
María Galdo. Marine Engines Performance and Emissions. Journal of Marine Science and Engineering 2021, 9, 280 .
AMA StyleMaría Galdo. Marine Engines Performance and Emissions. Journal of Marine Science and Engineering. 2021; 9 (3):280.
Chicago/Turabian StyleMaría Galdo. 2021. "Marine Engines Performance and Emissions." Journal of Marine Science and Engineering 9, no. 3: 280.
Wind energy resources are subject to changes in climate, so the use of wind energy density projections in the near future is essential to determine the viability and profitability of wind farms at particular locations. Thus, a step forward in determining the economic assessment of floating offshore wind farms was taken by considering current and near-future wind energy resources in assessing the main parameters that determine the economic viability (net present value, internal rate of return, and levelized cost of energy) of wind farms. This study was carried out along the Atlantic coast from Brest to Cape St. Vincent. Results show that the future reduction in wind energy density (2%–6%) mainly affects the net present value (NPV) of the farm and has little influence on the levelized cost of energy (LCOE). This study provides a good estimate of the economic viability of OWFs (Offshore Wind Farms) by taking into account how wind resources can vary due to climate change over the lifetime of the farm.
Laura Castro-Santos; Maite Decastro; Xurxo Costoya; Almudena Filgueira-Vizoso; Isabel Lamas-Galdo; Americo Ribeiro; João Dias; Moncho Gómez-Gesteira. Economic Feasibility of Floating Offshore Wind Farms Considering Near Future Wind Resources: Case Study of Iberian Coast and Bay of Biscay. International Journal of Environmental Research and Public Health 2021, 18, 2553 .
AMA StyleLaura Castro-Santos, Maite Decastro, Xurxo Costoya, Almudena Filgueira-Vizoso, Isabel Lamas-Galdo, Americo Ribeiro, João Dias, Moncho Gómez-Gesteira. Economic Feasibility of Floating Offshore Wind Farms Considering Near Future Wind Resources: Case Study of Iberian Coast and Bay of Biscay. International Journal of Environmental Research and Public Health. 2021; 18 (5):2553.
Chicago/Turabian StyleLaura Castro-Santos; Maite Decastro; Xurxo Costoya; Almudena Filgueira-Vizoso; Isabel Lamas-Galdo; Americo Ribeiro; João Dias; Moncho Gómez-Gesteira. 2021. "Economic Feasibility of Floating Offshore Wind Farms Considering Near Future Wind Resources: Case Study of Iberian Coast and Bay of Biscay." International Journal of Environmental Research and Public Health 18, no. 5: 2553.
To exploit marine resources in a sustainable way, efficient management systems must be used such as green artificial reefs (GARs). These reefs are mostly made up of renewable and organic materials. When adopting the circular economy (CE) model, industrial processes must be reconsidered. By adapting how conventional artificial reefs (CARs) are engineered and produced to embrace the principles of the CE, certain materials can be used. Renewable resources are designed to be reintroduced into the biosphere without producing harmful organic residues or nutrients. Within a framework that covers economic, environmental and social considerations, this study offers four new proposals related to substituting the materials destined for the components in an artificial reef. For the first time, two different methodologies were applied to determine the best alternative in terms of its contribution to both sustainability and CE. From the results obtained, the best solutions are in line with substituting a certain amount of the cement and sand with mussel shells. The importance of the results lies in the fact that the canning industry in Galicia (northwest Spain) generates shell residues which promote grave environmental consequences.
Luis Carral; Carolina Camba Fabal; Mª Isabel Lamas Galdo; Mª Jesús Rodríguez-Guerreiro; Juan José Cartelle Barros. Assessment of the Materials Employed in Green Artificial Reefs for the Galician Estuaries in Terms of Circular Economy. International Journal of Environmental Research and Public Health 2020, 17, 8850 .
AMA StyleLuis Carral, Carolina Camba Fabal, Mª Isabel Lamas Galdo, Mª Jesús Rodríguez-Guerreiro, Juan José Cartelle Barros. Assessment of the Materials Employed in Green Artificial Reefs for the Galician Estuaries in Terms of Circular Economy. International Journal of Environmental Research and Public Health. 2020; 17 (23):8850.
Chicago/Turabian StyleLuis Carral; Carolina Camba Fabal; Mª Isabel Lamas Galdo; Mª Jesús Rodríguez-Guerreiro; Juan José Cartelle Barros. 2020. "Assessment of the Materials Employed in Green Artificial Reefs for the Galician Estuaries in Terms of Circular Economy." International Journal of Environmental Research and Public Health 17, no. 23: 8850.
In this work, a numerical model was developed to analyze the performance and emissions of a marine diesel engine, the Wärtsilä 6L 46. This model was validated using experimental measurements and was employed to analyze several pre-injection parameters such as pre-injection rate, duration, and starting instant. The modification of these parameters may lead to opposite effects on consumption and/or emissions of nitrogen oxides (NOx), carbon monoxide (CO), and hydrocarbons (HC). According to this, the main goal of the present work is to employ a multiple-criteria decision-making (MCDM) approach to characterize the most appropriate injection pattern. Since determining the criteria weights significantly influences the overall result of a MCDM problem, a subjective weighting method was compared with four objective weighting methods: entropy, CRITIC (CRiteria Importance Through Intercriteria Correlation), variance, and standard deviation. The results showed the importance of subjectivism over objectivism in MCDM analyses. The CRITIC, variance, and standard deviation methods assigned more importance to NOx emissions and provided similar results. Nevertheless, the entropy method assigned more importance to consumption and provided a different injection pattern.
Maria Isabel Lamas; Laura Castro-Santos; Christina Rodriguez. Optimization of a Multiple Injection System in a Marine Diesel Engine through a Multiple-Criteria Decision-Making Approach. Journal of Marine Science and Engineering 2020, 8, 946 .
AMA StyleMaria Isabel Lamas, Laura Castro-Santos, Christina Rodriguez. Optimization of a Multiple Injection System in a Marine Diesel Engine through a Multiple-Criteria Decision-Making Approach. Journal of Marine Science and Engineering. 2020; 8 (11):946.
Chicago/Turabian StyleMaria Isabel Lamas; Laura Castro-Santos; Christina Rodriguez. 2020. "Optimization of a Multiple Injection System in a Marine Diesel Engine through a Multiple-Criteria Decision-Making Approach." Journal of Marine Science and Engineering 8, no. 11: 946.
The aim of the present paper is to provide the state of the works in the field of hydrodynamics and computational simulations to analyze biomimetic marine propulsors. Over the last years, many researchers postulated that some fish movements are more efficient and maneuverable than traditional rotary propellers, and the most relevant marine propulsors which mimic fishes are shown in the present work. Taking into account the complexity and cost of some experimental setups, numerical models offer an efficient, cheap, and fast alternative tool to analyze biomimetic marine propulsors. Besides, numerical models provide information that cannot be obtained using experimental techniques. Since the literature about trends in computational simulations is still scarce, this paper also recalls the hydrodynamics of the swimming modes occurring in fish and summarizes the more relevant lines of investigation of computational models.
M. I. Lamas; C. G. Rodriguez. Hydrodynamics of Biomimetic Marine Propulsion and Trends in Computational Simulations. Journal of Marine Science and Engineering 2020, 8, 479 .
AMA StyleM. I. Lamas, C. G. Rodriguez. Hydrodynamics of Biomimetic Marine Propulsion and Trends in Computational Simulations. Journal of Marine Science and Engineering. 2020; 8 (7):479.
Chicago/Turabian StyleM. I. Lamas; C. G. Rodriguez. 2020. "Hydrodynamics of Biomimetic Marine Propulsion and Trends in Computational Simulations." Journal of Marine Science and Engineering 8, no. 7: 479.
The goal of this work is to carry out an economic analysis of a novel floating offshore wind structure, of which the main material is concrete: the SATH® platform. It takes a step forward in floating marine wind energy research, in which traditional platforms are mainly composed of steel. The technique to calculate the costs of the platform and the economic parameters to decide if the farm is economically feasible are explained in the paper. This case study analyzes a possible farm of 500 MW located in Portugal and several scenarios considering different electric tariffs and capital costs (Scenario 1: electric tariff of 50 €/MWh and 6% of capital cost; Scenario 2: electric tariff of 50 €/MWh and 8% of capital cost; Scenario 3: electric tariff of 150 €/MWh and 6% of capital cost; Scenario 4: electric tariff of 150 €/MWh and 8% of capital cost). Results show the economic feasibility of a farm with the characteristics of Scenarios 3 and 4. This work is significant in order to provide a new approach to analyzing traditional floating offshore wind structures, which can represent a path towards the future of floating offshore renewable energy technologies.
Eugenio Baita-Saavedra; David Cordal-Iglesias; Almudena Filgueira-Vizoso; Àlex Morató; Isabel Lamas-Galdo; Carlos Álvarez-Feal; Luis Carral; Laura Castro-Santos. An Economic Analysis of An Innovative Floating Offshore Wind Platform Built with Concrete: The SATH® Platform. Applied Sciences 2020, 10, 3678 .
AMA StyleEugenio Baita-Saavedra, David Cordal-Iglesias, Almudena Filgueira-Vizoso, Àlex Morató, Isabel Lamas-Galdo, Carlos Álvarez-Feal, Luis Carral, Laura Castro-Santos. An Economic Analysis of An Innovative Floating Offshore Wind Platform Built with Concrete: The SATH® Platform. Applied Sciences. 2020; 10 (11):3678.
Chicago/Turabian StyleEugenio Baita-Saavedra; David Cordal-Iglesias; Almudena Filgueira-Vizoso; Àlex Morató; Isabel Lamas-Galdo; Carlos Álvarez-Feal; Luis Carral; Laura Castro-Santos. 2020. "An Economic Analysis of An Innovative Floating Offshore Wind Platform Built with Concrete: The SATH® Platform." Applied Sciences 10, no. 11: 3678.
In the present work, a numerical model was developed to analyze a commercial diesel engine. The adequacy of this model was validated using experimental results. This model was employed to study several pre-injection strategies. Particularly, the pre-injection rate, duration and starting instant were analyzed in the ranges 5% to 25%, 1° to 5° and −22° to −18°, respectively. The effect on consumption and emissions of NOx, CO, and HC wereas evaluated. Since some of these configurations have opposite effects on consumption and/or emissions, it is necessary to develop a formal tool to characterize the most appropriate injection pattern. To this end, a multiple-criteria decision making approach was employed. It was found that the injection duration must remain as low as possible due to significant reductions in NOx. The most appropriate injection pattern resulted 1° pre-injection duration, 20% pre-injection rate, and −19° pre-injection starting instant. This configuration leads to increments of 6.7% in consumption, 3.47% in CO, and 3.83% in HC but reduces NOx by 34.67% in comparison with the case without pre-injection.
María Isabel Lamas Galdo; Laura Castro-Santos; Carlos G. Rodríguez Vidal. Selection of an Appropriate Pre-Injection Pattern in a Marine Diesel Engine Through a Multiple-Criteria Decision Making Approach. Applied Sciences 2020, 10, 2482 .
AMA StyleMaría Isabel Lamas Galdo, Laura Castro-Santos, Carlos G. Rodríguez Vidal. Selection of an Appropriate Pre-Injection Pattern in a Marine Diesel Engine Through a Multiple-Criteria Decision Making Approach. Applied Sciences. 2020; 10 (7):2482.
Chicago/Turabian StyleMaría Isabel Lamas Galdo; Laura Castro-Santos; Carlos G. Rodríguez Vidal. 2020. "Selection of an Appropriate Pre-Injection Pattern in a Marine Diesel Engine Through a Multiple-Criteria Decision Making Approach." Applied Sciences 10, no. 7: 2482.
Many seas in the world are productive but limited to a few pelagic species, highly influenced by environmental conditions. This dependency makes necessary to develop solutions in order to promote wealth and biodiversity in productive regions. One of the recommended solutions to enrich the seas is the implantation of artificial reefs. These reefs mimic the environment and do not alter the preexistent equilibrium. Current studies about artificial reefs have focused on experimental observations. An alternative to these experimental analyses is CFD (Computational Fluid Dynamics). The main advantage of numerical simulations is that these provide much more information at a lower cost and less time. In this regard, this paper presents a numerical simulation of an artificial reef in order to analyze the most relevant hydrodynamic characteristics.
Maria Isabel Lamas Galdo; Patrick Roger Townsend Valencia; Maria Jesus Rodriguez Guerreiro; Laura Castro Santos; Luis Manuel Carral Couce. Numerical Model to Analyze an Artificial Reef. Proceeding of the VI International Ship Design & Naval Engineering Congress (CIDIN) and XXVI Pan-American Congress of Naval Engineering, Maritime Transportation and Port Engineering (COPINAVAL) 2020, 357 -364.
AMA StyleMaria Isabel Lamas Galdo, Patrick Roger Townsend Valencia, Maria Jesus Rodriguez Guerreiro, Laura Castro Santos, Luis Manuel Carral Couce. Numerical Model to Analyze an Artificial Reef. Proceeding of the VI International Ship Design & Naval Engineering Congress (CIDIN) and XXVI Pan-American Congress of Naval Engineering, Maritime Transportation and Port Engineering (COPINAVAL). 2020; ():357-364.
Chicago/Turabian StyleMaria Isabel Lamas Galdo; Patrick Roger Townsend Valencia; Maria Jesus Rodriguez Guerreiro; Laura Castro Santos; Luis Manuel Carral Couce. 2020. "Numerical Model to Analyze an Artificial Reef." Proceeding of the VI International Ship Design & Naval Engineering Congress (CIDIN) and XXVI Pan-American Congress of Naval Engineering, Maritime Transportation and Port Engineering (COPINAVAL) , no. : 357-364.
This work analyzes NOx reduction in a marine diesel engine using ammonia injection directly into the cylinder and compares this procedure with water injection. A numerical model based on the so-called inert species method was applied. It was verified that ammonia injection can provide almost 80% NOx reduction for the conditions analyzed. Furthermore, it was found that the effectiveness of the chemical effect using ammonia is extremely dependent on the injection timing. The optimum NOx reduction was obtained when ammonia is injected during the expansion stroke, while the optimum injection timing using water is near top dead center. Chemical, thermal, and dilution effects of both ammonia and water injection were compared. The chemical effect was dominant in the case of ammonia injection. On the other hand, water injection reduces NOx through dilution and, more significantly, through a thermal effect.
María Isabel Lamas Galdo; Laura Castro-Santos; Carlos G. Rodriguez Vidal. Numerical Analysis of NOx Reduction Using Ammonia Injection and Comparison with Water Injection. Journal of Marine Science and Engineering 2020, 8, 109 .
AMA StyleMaría Isabel Lamas Galdo, Laura Castro-Santos, Carlos G. Rodriguez Vidal. Numerical Analysis of NOx Reduction Using Ammonia Injection and Comparison with Water Injection. Journal of Marine Science and Engineering. 2020; 8 (2):109.
Chicago/Turabian StyleMaría Isabel Lamas Galdo; Laura Castro-Santos; Carlos G. Rodriguez Vidal. 2020. "Numerical Analysis of NOx Reduction Using Ammonia Injection and Comparison with Water Injection." Journal of Marine Science and Engineering 8, no. 2: 109.
In order to reduce NOx emissions in internal combustion engines, the present work analyzes a measurement which consists of injecting ammonia directly into the combustion chamber. A commercial compression ignition engine fueled with a hydrogen-diesel blend was studied numerically. It was verified that the flow rate shape in which the ammonia was injected, particularly rectangular, triangular, or parabolic, as well as the injection duration had an important influence on NOx reduction. A 11.4% improvement in NOx reduction, corresponding to an overall reduction of 78.2% in NOx, was found for parabolic injection shape and 1º injection duration. The effect on carbon dioxide, carbon monoxide, and hydrocarbon emissions, as well as brake-specific consumption, was negligible.
M. I. Lamas; C. G. Rodriguez. NOx Reduction in Diesel-Hydrogen Engines Using Different Strategies of Ammonia Injection. Energies 2019, 12, 1255 .
AMA StyleM. I. Lamas, C. G. Rodriguez. NOx Reduction in Diesel-Hydrogen Engines Using Different Strategies of Ammonia Injection. Energies. 2019; 12 (7):1255.
Chicago/Turabian StyleM. I. Lamas; C. G. Rodriguez. 2019. "NOx Reduction in Diesel-Hydrogen Engines Using Different Strategies of Ammonia Injection." Energies 12, no. 7: 1255.
The present paper proposes a Computational Fluid Dynamics model to analyze the operation cycle and exhaust gas composition in a four-stroke marine diesel engine, the Wärtsilä 6L 46. Once validated, the numerical model was employed to study the influence of several pre-injection parameters such as pre-injection rate, duration, starting instant and number of pre-injections. The purpose is to reduce consumption and emissions, especially nitrogen oxides, due to the current increasingly restrictive legislation. It was found that the fuel injection is a critical factor influencing combustion and emission characteristics. Important nitrogen oxides emission reductions were obtained for the parameters analyzed. Particularly, a 31.9% nitrogen oxides reduction was obtained using 20% pilot injection, 65.7% advancing 4º the pre-injection start angle, 20.1% shorting 4º the pre-injection duration and 36.7% using 4 pre-injections. A slight increment of hydrocarbons, carbon monoxide and consumption was obtained, lower than 5% for almost all the cases analyzed, and a negligible effect on carbon dioxide emissions.
Maria Isabel Lamas; Juan De Dios Rodríguez; Laura Castro-Santos; Luis Manuel Carral. Effect of multiple injection strategies on emissions and performance in the Wärtsilä 6L 46 marine engine. A numerical approach. Journal of Cleaner Production 2018, 206, 1 -10.
AMA StyleMaria Isabel Lamas, Juan De Dios Rodríguez, Laura Castro-Santos, Luis Manuel Carral. Effect of multiple injection strategies on emissions and performance in the Wärtsilä 6L 46 marine engine. A numerical approach. Journal of Cleaner Production. 2018; 206 ():1-10.
Chicago/Turabian StyleMaria Isabel Lamas; Juan De Dios Rodríguez; Laura Castro-Santos; Luis Manuel Carral. 2018. "Effect of multiple injection strategies on emissions and performance in the Wärtsilä 6L 46 marine engine. A numerical approach." Journal of Cleaner Production 206, no. : 1-10.
M.I. Lamas; C.G. Rodriguez. Numerical model to analyze Nox reduction by ammonia injection in diesel-hydrogen engines. International Journal of Hydrogen Energy 2017, 42, 26132 -26141.
AMA StyleM.I. Lamas, C.G. Rodriguez. Numerical model to analyze Nox reduction by ammonia injection in diesel-hydrogen engines. International Journal of Hydrogen Energy. 2017; 42 (41):26132-26141.
Chicago/Turabian StyleM.I. Lamas; C.G. Rodriguez. 2017. "Numerical model to analyze Nox reduction by ammonia injection in diesel-hydrogen engines." International Journal of Hydrogen Energy 42, no. 41: 26132-26141.
The present paper proposes a CFD model to study sulphur dioxide (SO2) absorption in seawater. The focus is on the treatment of marine diesel engine exhaust gas. Both seawater and distilled water were compared to analyze the effect of seawater alkalinity. The results indicate that seawater is more appropriate than distilled water due to its alkalinity, obtaining almost 100% cleaning efficiency for the conditions analyzed. This SO2 reduction meets the limits of SOx emission control areas (SECA) when operating on heavy fuel oil. These numerical simulations were satisfactory validated with experimental tests. Such data are essential in designing seawater scrubbers and judging the operating cost of seawater scrubbing compared to alternative fuels.
M. I. Lamas; C. G. Rodríguez; J. D. Rodríguez; J. Telmo. Numerical Model of SO2 Scrubbing with Seawater Applied to Marine Engines. Polish Maritime Research 2016, 23, 42 -47.
AMA StyleM. I. Lamas, C. G. Rodríguez, J. D. Rodríguez, J. Telmo. Numerical Model of SO2 Scrubbing with Seawater Applied to Marine Engines. Polish Maritime Research. 2016; 23 (2):42-47.
Chicago/Turabian StyleM. I. Lamas; C. G. Rodríguez; J. D. Rodríguez; J. Telmo. 2016. "Numerical Model of SO2 Scrubbing with Seawater Applied to Marine Engines." Polish Maritime Research 23, no. 2: 42-47.
Nowadays, it is well known that offshore is a promising alternative for energy production. Many researchers have built different kinds of machines. The main problem is that it is very important to fully understand the hydrodynamics of wind turbines to design an optimal mechanism. For this reason, CFD (Computational Fluid Dynamics) has become a very powerful technique because it solves the governing equations of conservation of mass and momentum so as to obtain the fluid flow characteristics. CFD analyses provide details of the velocity and pressure fields, as well as the hydrodynamic forces, cruising velocity, power and efficiency. This is very useful to identify the advantages and disadvantages of new designs of wind turbines. In this regard, this chapter illustrates how to realize a 3D CFD model of a wind turbine, from the initial stage of CAD designing and meshing to the final stage of analysis of the results.
M. I. Lamas; C. G. Rodríguez. CFD Applied to Floating Offshore Wind Energy. Smart and Sustainable Planning for Cities and Regions 2016, 77 -87.
AMA StyleM. I. Lamas, C. G. Rodríguez. CFD Applied to Floating Offshore Wind Energy. Smart and Sustainable Planning for Cities and Regions. 2016; ():77-87.
Chicago/Turabian StyleM. I. Lamas; C. G. Rodríguez. 2016. "CFD Applied to Floating Offshore Wind Energy." Smart and Sustainable Planning for Cities and Regions , no. : 77-87.
The current restrictions on emissions from marine engines, particularly sulphur oxides (SOx ), nitrogen oxides (NOx ) and carbon dioxide (CO2 ), are compelling the shipping industry to a change of tendency. In the recent years, many primary and secondary reduction techniques have been proposed and employed in marine engines. Nevertheless, the increasingly restrictive legislation makes it very difficult to continue developing efficient reduction procedures at competitive prices. According to this, the paper presents the possibility to employ alternative fuels. A numerical model was developed to analyze the combustion process and emissions using oil fuel, natural gas and hydrogen. A commercial marine engine was studied, the Wärtsilä 6L 46. It was found, that hydrogen is the cleanest fuel regarding CO2 , hydrocarbons (HC) and carbon monoxide (CO). Nevertheless, it is very expensive for marine applications. Natural gas is cheaper and cleaner than fuel oil regarding CO2 and CO emissions. Still, natural gas emits more NOx and HC than oil fuel. SOx depends basically on the sulphur content of each particular fuel.
Lamas M.I.; Rodríguez C.G.; Telmo J.; Rodríguez J.D.. Numerical Analysis of Emissions from Marine Engines Using Alternative Fuels. Polish Maritime Research 2015, 22, 48 -52.
AMA StyleLamas M.I., Rodríguez C.G., Telmo J., Rodríguez J.D.. Numerical Analysis of Emissions from Marine Engines Using Alternative Fuels. Polish Maritime Research. 2015; 22 (4):48-52.
Chicago/Turabian StyleLamas M.I.; Rodríguez C.G.; Telmo J.; Rodríguez J.D.. 2015. "Numerical Analysis of Emissions from Marine Engines Using Alternative Fuels." Polish Maritime Research 22, no. 4: 48-52.
The present paper reports a numerical analysis to study the heat transfer mechanisms in nucleate boiling. Three fluids have been analyzed, water, ammonia and R134a and several heat transfer mechanisms such as thermocapillarity, evaporation of the superheated liquid surrounding the bubble, three-phase contact line evaporation, conduction and convection. The individual contribution of each mechanism to the global wall heat transfer has been evaluated. It has been determined that convection is the dominant mechanism for the three fluids analyzed. Concerning the remaining mechanisms, the evaporation of superheated liquid surrounding the bubble and three-phase contact line evaporation do not contribute more than one-third of the overall heat transfer. Contact line evaporation represents between 9 and 26.5 % of the evaporation heat transfer. Both thermocapillarity and transient conduction slightly contribute to the overall heat transfer.
M. I. Lamas; P. Fariñas; A. Arce; M. L. Sánchez. A numerical evaluation of the contribution of different heat transfer mechanisms in nucleate boiling. Journal of the Brazilian Society of Mechanical Sciences and Engineering 2015, 37, 1543 -1553.
AMA StyleM. I. Lamas, P. Fariñas, A. Arce, M. L. Sánchez. A numerical evaluation of the contribution of different heat transfer mechanisms in nucleate boiling. Journal of the Brazilian Society of Mechanical Sciences and Engineering. 2015; 37 (5):1543-1553.
Chicago/Turabian StyleM. I. Lamas; P. Fariñas; A. Arce; M. L. Sánchez. 2015. "A numerical evaluation of the contribution of different heat transfer mechanisms in nucleate boiling." Journal of the Brazilian Society of Mechanical Sciences and Engineering 37, no. 5: 1543-1553.
Taking into account the increasingly stringent legislation on emissions from marine engines, this work aims to analyze several internal engine modifications to reduce NOx (nitrogen oxides) and other pollutants. To this end, a numerical model was employed to simulate the operation cycle and characterize the exhaust gas composition. After a preliminary validation process was carried out using experimental data from a four-stroke, medium-speed marine engine, the numerical model was employed to study the influence of several internal modifications, such as water addition from 0 to 100% water to fuel ratios, exhaust gas recirculation from 0 to 100% EGR rates, modification of the overlap timing from 60 to 120°, modification of the intake valve closing from 510 to 570°, and modification of the cooling water temperature from 70 to 90 °C. NOx was reduced by nearly 100%. As expected, it was found that, by lowering the combustion temperature, there is a notable reduction in NOx, but an increase in CO (carbon monoxide), HC (hydrocarbons) and consumption
M.I. Lamas; C.G. Rodríguez; J.D. Rodríguez; J. Telmo. Internal modifications to reduce pollutant emissions from marine engines. A numerical approach. International Journal of Naval Architecture and Ocean Engineering 2013, 5, 493 -501.
AMA StyleM.I. Lamas, C.G. Rodríguez, J.D. Rodríguez, J. Telmo. Internal modifications to reduce pollutant emissions from marine engines. A numerical approach. International Journal of Naval Architecture and Ocean Engineering. 2013; 5 (4):493-501.
Chicago/Turabian StyleM.I. Lamas; C.G. Rodríguez; J.D. Rodríguez; J. Telmo. 2013. "Internal modifications to reduce pollutant emissions from marine engines. A numerical approach." International Journal of Naval Architecture and Ocean Engineering 5, no. 4: 493-501.
The present paper reports a study of transient thermocapillary flows around non-condensable gas bubbles on heated stripes and wires through a tri-dimensional numerical model. In order to validate the numerical model, the obtained results have been satisfactory compared with experimental data obtained elsewhere. Present results coincide with previously obtained ones in confirming that thermocapillary convection is the dominant mechanism responsible for the observed jets streaming out from bubbles on heated surfaces. Temperature and flow fields have been obtained for water and isobutyl alcohol and several bubble-heated surface configurations. It has been determined that gravity tends to deviate upwards the jets streaming out from the bubbles in vertical wires and its effects are significant in the range of high Rayleigh numbers (higher than 1000), though in the neighborhood of the bubbles, thermocapillary convection is more significant. In addition, the heat transfer enhancement by thermocapillary flows is restricted to a region encompassing 2–4 bubble radii.
M. I. Lamas; J. M. Saiz Jabardo; Alberto Arce. Thermocapillary and not thermocapillary convection around non-condensable gas bubbles. Journal of the Brazilian Society of Mechanical Sciences and Engineering 2013, 35, 493 -503.
AMA StyleM. I. Lamas, J. M. Saiz Jabardo, Alberto Arce. Thermocapillary and not thermocapillary convection around non-condensable gas bubbles. Journal of the Brazilian Society of Mechanical Sciences and Engineering. 2013; 35 (4):493-503.
Chicago/Turabian StyleM. I. Lamas; J. M. Saiz Jabardo; Alberto Arce. 2013. "Thermocapillary and not thermocapillary convection around non-condensable gas bubbles." Journal of the Brazilian Society of Mechanical Sciences and Engineering 35, no. 4: 493-503.