Search

In this research, a mathematical model was built to analyze the energy recovery potential of a annular thermoelectric generator. For the study, the conditions of mass flow and exhaust gas temperature of an internal combustion engine, which was operated at five load percentages (20%, 40%, 60%, 80% and 100%), were used. The study involves an analysis of the power output, loss power and net power of the annular TEG. Additionally, the effect of geometrical changes such as the height of the thermoelectric modules, and variations in the length and width of the heat exchanger are evaluated. The analysis of the results shows that the change in the engine load causes an increase of 8.40% and 15.41% in the mass flow and exhaust gas temperature. These types of changes lead to a 31.90% and 19.11% increase in electrical power and efficiency of the annular TEG. Additionally, the increase in the length of the P-type and N-type semiconductors leads to a 5.41% and 2.42% increase in power output and efficiency. The variation in the geometrical parameters of the heat exchanger demonstrates the existence of an optimal geometry that maximizes the electric power of the annular TEG. Therefore, a complete parametric analysis is required to balance the heat transfer capacity and loss power due to the hydraulic resistance of the TEG in the engine exhaust system. [ABSTRACT FROM AUTHOR]

The present investigation analyzes the influence of water content in a biodiesel blend using palm oil mill effluent: POME (8%). Two water emulsion blends were tested: POME (8%) + H2O (5%) and POME (8%) + H2O (10%). The tests were performed on a stationary diesel engine operating at four load conditions (25%, 50%, 75% and 100%). From the results, it is shown that the blends POME (8%) + H2O (5%) and POME (8%) + H2O (10%) allow a decrease of 2.2% and 4.7% in NOx emissions. In this way, the NOx formation problems of biodiesel are minimized. The evaporation of the water microparticles in the blends POME (8%) + H2O (5%) and POME (8%) + H2O (10%) improves the homogeneity between the air and the fuel. This contributes to a 2.65% decrease in BSFC and a 1.65% increase in BTE compared to POME (8%). Additionally, water emulsions achieve a 14.6%, 7.3%, 13.4%, 1.8%, and 14.1% reduction in CO, CO2, HC, NOx, and smoke opacity emissions compared to conventional diesel. In general, the emulsified blends POME (8%) + H2O (5%) and POME (8%) + H2O (10%) contribute to a greater reduction in engine pollutant emissions, as well as an improvement in engine performance parameters when compared to POME (8%). [ABSTRACT FROM AUTHOR]

This research evaluates the recovery potential, performance parameters, energy distribution, and economic savings of a stationary diesel engine operating with the injection of hydrogen gas and installing a thermoelectric generator as an energy recovery system in the engine exhaust. Four operational conditions were considered for the research development: 25%, 50%, 75%, and 100%. The test engine operated with diesel and a mixture of diesel + hydrogen gas (H15%). The results show that the presence of hydrogen gas allows a 40.37% increase in the thermoelectric generator's net power, compensating for the TEG's low energy efficiency. Additionally, a reduction of 7.55% in the BSFC and 7.71% in the thermal efficiency is achieved. The addition of hydrogen in the engine allows the TEG to reach an electrical power generated of 74.27 W. The mixture of diesel fuel + H15%, and the integration of the TEG, allows for reaching a maximum thermal efficiency of 33.83%. The higher power recovered by the TEG due to the presence of hydrogen gas causes an increase of 28% in economic savings, which facilitates the economic viability of implementing this type of recovery technology. [ABSTRACT FROM AUTHOR]

The current research has evaluated the effects of cylinder injection signal override technology in internal combustion engines on cylinder liner conditions, friction forces, power losses, and fuel economy. For the development of the research, a mathematical model has been built to describe the tribological behavior between the cylinder liner and the compression ring. The results have showed that the cylinder injection signal override technology leads to a 14.3% increase in the maximum pressure in the cylinder chamber, a 9.2% increase in the cylinder liner temperature, and a 13.6% reduction in the lubrication thickness for the cylinders that remain active. Additionally, a 23.2% and 34.4% increase in power losses associated with friction force and exhaust leakage is evident. Despite the above, cylinder injection signal override allows a 16.9% decrease in engine fuel consumption, which reduces engine operating costs. In general, cylinder injection signal override technology presents a benefit for decreasing engine fuel consumption. However, it is necessary to consider the loss of power and additional wear caused by the engine components. [ABSTRACT FROM AUTHOR]

This research aims to evaluate the effect of surface texturing on the cylinder liner on tribological characteristics such as minimum oil film thickness, power losses, and dynamic forces (asperity contact force, hydrodynamic force, and total friction force). The research covers the study of two lubrication conditions: (a) starved and (b) fully flooded. The surface texturing on the cylinder liner was produced by dimpling. For the development of the study, a numerical model was used with MATLAB® software. The analysis of the dynamic forces demonstrated that dimples in the cylinder liner led to a 10.10% decrease in the asperity contact force between the piston ring and the cylinder liner. On the other hand, surface texturing allows a 4.32% increase in the minimum oil film thickness, which results in a 6.05% decrease in power loss. The surface texturing improves the engine's energy efficiency by 3.11%. The fully flooded lubrication condition leads to higher estimates of the frictional force present in the combustion chamber. In general, the mathematical model allows estimating the tribological behavior between the compression ring and the cylinder liner, which is a useful tool for evaluating strategies to minimize the power lost due to surface friction. [ABSTRACT FROM AUTHOR]

In this research, a methodology is proposed for the prediction of the electrical characteristics of thermoelectric modules in thermoelectric generation systems. The development of the research consists of the use of a multiphysics numerical simulation model, with the aim of evaluating in a coupled and simultaneous way the behavior of the fluid and the thermal and electrical characteristics present in the thermoelectric modules. For the study, the influence of boundary conditions, electric resistance, and the model's predictive capacity have been evaluated. In general, the use of the multiphysics model results in a higher estimate of the output voltage and power. Increases of 10% and 15% in the maximum values of electrical voltage and power compared to a model without thermoelectric effects have been demonstrated. Additionally, the prediction of the behavior of the thermoelectric module without thermoelectric phenomena such as the Joule effect and the Thomson effect produces a lower estimate of the electrical performance, especially in high-temperature conditions. In general, the development of the study has made it possible to demonstrate that multiphysics models are necessary for a real estimation of the electrical performance of thermoelectric modules, allowing them to reach a prediction error of 2.0% and 2.4% in the parameters of voltage and output power. [ABSTRACT FROM AUTHOR]

In the current investigation, the influence of hydrogen gas on the energy and exergetic distribution and the properties of the lubricating oil in gasoline engines were studied. For the development of the investigation, four loads (25%, 50%, 75%, and 100%) and three percentages of hydrogen gas injection (5%, 10%, and 15%) were defined. The mixture of gasoline and hydrogen gas leads to an improvement in the combustion process of the engine. It was found that the injection of 15% hydrogen in the gasoline engine causes an increase of 5.09% and 5.70% in energy and exergetic efficiency. Additionally, a reduction in brake specific fuel consumption was demonstrated by 0.43%, 0.86%, and 1.58% with mixtures G(100%) + H2(5%), G(100%) +H2(10%), and G(100%) + H2(15%) compared to pure gasoline. The mixture of gasoline and hydrogen gas allows to the improvement of the combustion characteristics of the engine. However, hydrogen injection produces negative effects on the lubricating oil system, such as the increased presence of wear metal debris and decreased lubricant viscosity. The foregoing implies a shortening in the useful life of the lubricating oil and an increased risk of wear on engine parts. [ABSTRACT FROM AUTHOR]

In this research, an experimental study of the influence of factors such as electrical characteristics, type and concentration of electrolyte substances, and operation time on the hydrogen gas production rate and efficiency in electrolyzer devices has been carried out. Additionally, the impact of the percentage of hydrogen gas on the performance parameters in a stationary diesel engine, such as fuel consumption, energy efficiency, and exergy efficiency, has been considered. The results have demonstrated an increase of 21.6% and 18.7% in the production rate due to the electrolyzer's current and voltage levels. However, excessive increases in these electrical parameters can lead to a 38% and 33% reduction in electrolyzer efficiency. The use of KOH electrolyte presents a higher hydrogen gas production capacity compared to NaOH. The results show a 3% increase in hydrogen gas production in the KOH electrolyte concerning NaOH. The presence of hydrogen allows a 3% decrease in the BSFC and a 1.3% and 2.4% increase in the energy and exergy efficiency of the engine. [ABSTRACT FROM AUTHOR]

The working fluid normally used in Organic Rankine Cycle (ORC) systems is R245fa. However, due to stricter regulations for emission control, this type of fluid will be phased out. Due to the above, in this research, the performance parameters of ORC systems operating at low temperatures with different working fluids are analyzed. The research was carried out by numerical simulation using MATLAB® software and the CoolProp® database. The working fluids investigated were R245fa, R1233zd(E), and R1336mzz(Z), respectively. The analysis of the performance parameters involves the net power, thermal efficiency, and exergetic efficiency of the ORC system. From the results obtained, it was shown that the net power obtained with the working fluid R1233zd(E) and R1336mzz(Z) are 3.5% and 6% lower compared to R245fa. However, the higher evaporation temperature of R1233zd (E) allows achieving a higher thermal and exergetic efficiency of the thermal cycle. R1233zd(E) enables a 3.8% and 4.8% improvement in thermal and exergetic efficiency compared to R245fa working fluid. R1336mzz(Z) working fluid is not recommended as a replacement for R245fa. In general, R1233zd(E) has the potential to replace R245fa, which is one of the main working fluids used despite its high level of CO² emissions. [ABSTRACT FROM AUTHOR]

Thermoelectric generators are a potential alternative to improve the performance of internal combustion engines. In this research, an analysis of the energy recovery capacity, fuelsaving, emission reduction, and economic analysis of a thermoelectric generator located in the exhaust system of a stationary diesel engine has been carried out. For the experimental tests, three types of fuels (D100%, BP5%, and BP10%) have been used, as well as changes in the conditions of torque (3 - 6 Nm) and rotational speed (3000 - 3800 rpm) of the engine. The results show a recovery capacity of 55.5 W, 66.5 W, and 70.6 W for fuels D100%, BP5%, and BP10%, representing recovered energy of 2.33%, 2.78%, and 2.96% compared to the output power of the engine. The use of the thermoelectric generator has allowed achieving fuel savings of 2.9%. The implementation of the TEG implies a reduction in emissions (CO², HC, and NOx) of 1.61%, 1.82%, and 2.07% for D100%, BP5%, and BP10% fuels. Economic savings of 528 USD/kWh (36 months) have been achieved, showing the technology's potential, especially in high-power engines or regions with high fuel costs. Future studies will focus on improving the thermoelectric generator's recovery capacity. [ABSTRACT FROM AUTHOR]

Currently, an improvement in the energy performance of energy equipment and processes is required due to the high global energy consumption and polluting emissions. Centrifugal pumps have been extensively implemented in several processes for fluid transportation. Due to the above, in this research, a methodology is proposed. A backpropagation neural network and a theoretical model are used together to predict energy performance parameters such as real head, power consumption, and efficiency. The neural network is built based on different geometric and operational parameters. The results obtained show that the proposed neural network allows predicting the real head, the power consumption, and the efficiency parameters with a maximum error of 0.26%, 2.27%, and 0.15%, which is a precision similar to the one obtained in methodologies such as computational fluid mechanics. The inclusion of the theoretical model in the neuronal network makes it possible to reduce the error within the energy performance prediction of the turbomachinery. In general, an increase in the maximum error of 34.61%, 61.67%, and 126.67% has been observed for the real head, the power consumption, and the efficiency when the theoretical model is not considered. In general, the use of the proposed neural network allows predicting with high precision and rapidly energy performance parameters such as real head, power consumption, and efficiency, which results in a methodology with the potential to be used in optimization processes in centrifugal pumps. [ABSTRACT FROM AUTHOR]

In this investigation, a study of the tribological and dynamic characteristics present in the compression ring is executed for different engine conditions. A series of numerical simulations has been carried out using the OpenFOAM software for the study. The simulation conditions have been based on the parameters measured on a diesel engine test bench. Different ranges of rotation speed, load, and lubrication oil temperature have been established for the analysis. The results show that the parameters of rotation speed and engine load significantly influence the tribological and dynamic conditions of the piston compression ring. An increase of 425 rpm and 136 Nm in the rotational speed and load of the engine causes an increase of 13% and 34% in the power loss due to friction. The Top Dead Center and the Bottom Dead Center are the locations most prone to experience critical wear and tear. Increasing the lubricating oil temperature increases the maximum friction force by 9%. In general, the proposed methodology allows for establishing a direct relationship between the operating conditions and the tribological characteristics in the compression ring that directly affect the efficiency and useful life of the engine. [ABSTRACT FROM AUTHOR]

This research has developed a methodology to estimate energy losses associated with auxiliary systems and mechanisms subject to friction in a stationary diesel engine. The study methodology is based on mathematical models used to calculate engine friction forces and power losses. The analysis involves the cooling, the lubrication, the fuel injection system, and the engine's valve train, bearings, and piston mechanism. A stationary diesel engine with four load conditions and three rotational speed conditions has been taken as a reference for the study. The analysis of the results has showed that fuel injection is the auxiliary system with the highest energy consumption. In general, the cooling system, the lubrication, and the injection represent loss energy equivalent to 0.3%, 0.5%, and 0.9% of the chemical energy of the fuel. The interaction between the cylinder liner and the piston skirt is the main source of energy loss associated with friction processes. For valve train mechanisms, bearings and pistons it has been evidenced that these represent 1.25%, 1.91%, and 5.26% of the chemical energy of the fuel. In general, the methodology proposed in this research is a tool that allows diagnosing energy losses in auxiliary systems and engine mechanisms, which is useful for evaluating future strategies focused on energy improvement. [ABSTRACT FROM AUTHOR]

This investigation experimentally examines the influence of hydroxy gas fumigation in a diesel engine fueled with a biodiesel blend derived from waste palm cooking oil (B10). For the experimental tests, a fixed rotation speed of 2000 rpm and a load condition of 50%, 75%, and 100% have been established. Hydroxy gas (HHO) has been added through the engine's air intake system at a flow of 0.5 lpm, 0.75 lpm, and 1 lpm. Results have demonstrated the positive effect of HHO fumigation on the combustion performance of the B10 blend. Moreover, a reduction of 4.3% in the BSFC and a 2.64% increase in peak pressure in B10 due to the presence of HHO have been observed. On the other hand, a decrease of 8.7%, 9.9%, and 22.8% in CO2, HC, and smoke opacity emissions has been evidenced with the addition of HHO in B10. B10 implementation has promoted NOx emission escalation. However, this increase has been only 1.23% compared to pure diesel. In conclusion, HHO enrichment favors combustion performance and emissions minimization, which represents a significant opportunity to mitigate the negative effect of the lower calorific power of these types of fuels. [ABSTRACT FROM AUTHOR]

The current research analyzes the effect of fuel preheating on performance parameters and emission characteristics in a stationary diesel engine fuelled with palm oil mill effluent biodiesel blends. The investigation has been carried out on an experimental test bench under four-engine load conditions. The fuel injection temperature range is set between 35-75 °C. From the results obtained, it has been possible to demonstrate that the preheating process allows the reduction of fuel consumption and an increase in the efficiency of the engine powered with POME 5 and POME 10 blends. The preheating process has the potential to reduce by 14 % BSFC and increase by 17% the BTE of the engine. Additionally, the results have showed a reduction potential of 17.2%, 16.5%, and 15.6% in CO2, HC, and smoke opacity emissions when preheating processes are used in POME biodiesel blends. In general, this type of strategy is a promising solution to incentivize the use of biodiesel blends from palm oil mill effluent. [ABSTRACT FROM AUTHOR]

The energy transition from fossil fuels to renewable fuels is constantly developing and implementing. It is the subject of worldwide research, seeking to curb climate change and the negative effects of pollution. An economic sector worldwide that generates a large amount of pollutants is the transport sector, which only uses fossil fuels. Accordingly, it is necessary to test renewable alternatives that reduce the pollution caused by the sector, trying to use the current automotive fleet. The purpose of this paper is to show the effects of the direct injection of hydrogen gas obtained using an alkaline electrolysis system in a single-cylinder internal combustion engine operated with Diesel fuel, managing to study the effects of hydrogen injection on the different engine parameters such as fuel consumption, rpm, torque, temperature, and exhaust gas analysis, performing a statistical analysis that allows determining the input variables that most influence the decrease in polluting gases CO and CO2 and the variation in fuel consumption in addition to engine performance. [ABSTRACT FROM AUTHOR]

In the current investigation, an analysis of the performance parameters and emissions has been carried out in a stationary diesel engine fed with an alternative fuel blend from industrial palm oil waste (Palm Oil Mill Effluent, POME). Additionally, the influence of hydroxy gas injection in the combustion chamber has been evaluated. A test engine, which has operated at four torque levels and at a constant speed of 3600 rpm, has been used for the study. The fuel blend tested has been POME10%, and the volumetric flow of the hydroxy gas has been 0.075 and 1 LPM. From the results, it has been possible to demonstrate that POME10% biodiesel causes inefficiency in fuel use due to less homogeneity and greater fuel injection than standard diesel. In general, it has been evidenced that POME10% causes a decrease of 3.3% and 3.8% in fuel pressure and in maximum engine efficiency. However, the presence of hydroxy gas makes it possible to offset these negative effects. Additionally, the combined use of POME10% and hydroxy gas allows a decrease of 8.0%, 9.2%, and 10.1% in CO2, HC, and smoke opacity emissions compared to the engine running only with the engine POME10%. In general, hydroxy gas is a promising alternative to offset the negative effects caused by the use of biodiesel from waste materials such as palm oil mill effluent. [ABSTRACT FROM AUTHOR]

In recent years, the high emission standards have grown the development of different strategies focused on the reduction of pollutants produced by combustion processes in energy transfer systems. For that reason, different studies have been developed to minimize fuel consumption and elevate internal combustion performance under different operating modes. Internal combustion engines are widely studied currently by means of advanced theories of thermal and fluid mechanics sciences with the aim to improve the energy transfer processes needed to transform the chemical energy generated in work during the complex fuel combustion process into the combustion chamber. Inexpensive methods have been developed to improve the internal combustion engine performance based on the understanding of chemical reactions and physical processes of mass and energy transfer. Mathematical and experimental models are employed to approximate the real working conditions, the physical phenomenon of the fuel flow injected into the combustion chamber of the internal combustion engine. Therefore, this paper proposes a predictive model that relates the fuel injection system with the combustion process and the heat transfer into the walls of the combustion chamber. External forces are considered during the internal combustion engine operation under real working conditions taking into account the dependent variables of the partial differential equations system that describes the internal combustion engine performance. A good agreement was reached between the experimental and predictive approaches. The results showed an error rate of less than 3 percent, considering a multiple linear regression model adjusted to the characterized internal combustion engine. [ABSTRACT FROM AUTHOR]

Engine system design is focused on steady and transient studies of the thermodynamic cycle based on the crankshaft angle and the heat release curve. Therefore, internal combustion engines have been studied in recent years for thermodynamic applications in order to increase their energy efficiency, durability, quieter, and vibration-free through predictive models based on their mechanical behavior considering different conditions with computational tools. Predictive models are considered as the diagnostic assessment of internal combustion engines due to the methodology employed in the acquisition of the experimental data based on the engine characterization of 4JJ1 Isuzu Diesel engines applied in the combustion chamber. In this paper, a thermodynamic predictive study is developed, taking into account the pressure signal and heat rejected range with the aim to predict the internal engine flow, mixture formation, coolant temperatures, and the combustion processes focused on the chemical and kinetic energy transfer into the combustion chamber. A maximum error rate of 7 percent between the experimental and modeled results, which allows high predictability in the proposed model, has been obtained. Nearby to the Top Dead Center has managed to follow the trend of the experimental behavior, despite being a critical area of modeling due to high temperatures, pressures, and combustion kinetics. [ABSTRACT FROM AUTHOR]

The qualitative and the quantitative analysis used to describe the energy transfer processes, which define the turbulent flow transport into the mechanical devices and thermal effects generated during the energy production processes, have been evolved in recent years with the application of the numerical method and computational tools used to generate an inexpensive analysis of the performance of the mechanical components and their influence in the energy production of the main thermodynamic cycles studied in science and engineering. The increase in energy production, conversion, and consumption has been influenced by the economic growth, which probably has caused the main effects of the current environmental pollution. Therefore, non-conventional energy resources have been applied in order to minimize conventional energy consumption and improve the energy transfer processes, which describe the application of the thermodynamic cycle. In this sense, a novel supercritical carbon dioxide (S - CO2) Brayton cycle has been computed in a virtual environment with MATLAB software in order to analyze the physical values that describe the thermodynamic behavior of the carbon dioxide flow into the two main variants: Recompression Cycle (RC), and Recompression with Main Compression Intercooling (MCIC). The first and the second laws of thermodynamics have been applied in a computational code in order to generate an inexpensive thermal efficiency prediction under real working conditions and verify the exergy destruction of the mechanical components, which conform to the thermodynamic cycles studied in this research. A good agreement has been determined during the comparison of the numerical data against the results of the previous research, with a low error rate of less than 2 percent. [ABSTRACT FROM AUTHOR]