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The problem of climate change and the reduction of fossil fuels has motivated the development of research focused on improving the efficiency of internal combustion engines. This research proposes a methodology based on mathematical models to determine the energy losses caused by auxiliary systems and friction processes in the engine. Therefore, models are proposed for calculating the energy losses in fuel injection, lubrication, and cooling system. In the same way, models are proposed for the energy losses due to friction in the piston, valve train, and bearings. Experimental tests are carried out on a single-cylinder diesel engine under different operating conditions to validate the proposed models. The results showed that the energy losses of the fuel injection, lubrication, and coolant system are equal to 0.61%, 0.30%, and 0.31% of the chemical energy of the injected fuel. In the case of the energy losses by friction processes, the piston, valve train, and bearings represent 5.47%, 1.34%, and 1.85% of the fuel energy, respectively. Additionally, the proposed model allows estimating the minimum lubrication film present in the piston, valve train, and bearings, which in the particular case of the present study were 0.63 µm, 0.10 µm, and 0.57 µm, respectively. In general, the methodology developed in the present work stands as a robust tool to evaluate the modifications and/or designs of auxiliary systems and friction processes to reduce the energy losses and protect the system from wear caused by lubrication problems. Additionally, the methodology allows evaluating the effect of different types of fuels on the lubrication conditions of the piston and the crankshaft bearings.

The contact between the piston rings and the cylinder liner is an interface with a strong influence on the tribological behavior and, therefore, directly affects the useful life of the engine components and fuel consumption. Due to this importance, the present investigation carried out an analysis of the effects of dimples and the honing groove in the cylinder liner on the tribological characteristics. A tribological model was developed to study the friction forces, minimum film thickness, and friction coefficient for the present investigation. Similarly, a computational fluid dynamics model was built to determine the dynamic movement of the piston. The validation of the numerical model showed a close similarity with the real behavior of the engine, obtaining an average relative error of 14%. The analysis of the results showed that a 3% increase in dimples’ density leads to a 3.79% increase in the minimum lubricant film and a 2.76% decrease in friction force. Additionally, it was shown that doubling the radius and depth of the dimple produces an increase of 3.86% and 1.91% in the thickness of the lubrication film. The most suitable distribution of the dimples on the surface of the cylinder liner corresponds to a square array. In general, the application of dimples and honing grooves in the cylinder liner are promising alternatives to reduce energy losses and minimize wear of engine components.

The objective of the present investigation is to analyze the tribological performance between the union of the cylinder liner and the compression ring under the influence of surface texturing and different lubrication boundary conditions. The analysis is carried out by developing a numerical model, which involves hydrodynamic pressure, lubrication film thickness, textured surface, dynamic forces, and lubrication boundary conditions (starved lubrication and fully flooded lubrication). MATLAB® software (The MathWorks Inc., Natick, MA, USA) is used to solve the equations developed. The results show that the application of a textured surface on the cylinder liner allows obtaining a reduction of 20% and 5% in the asperity contact force and in the total friction force. Additionally, the textured surface allows for a 4% increase in MOFT. In this way, it is possible to reduce the power loss. The implementation of a boundary condition of fully flooded lubrication produces an overestimation in the total friction force due to the greater prominence of the lubrication film. Implementing a textured surface in the ring profile is an alternative way to reduce power loss. The results show that this alternative allows an 8% reduction in power loss.

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In the present work, a numerical model is developed to investigate the influence of wear and misalignment on the bearings of a stationary diesel engine. The model implemented considers the effects of surface wear on the bearing, cavitation effects, and surface roughness. For the numerical analysis, changes in the surface roughness of , , and are defined, and changes in the bearing load of 50%, 75%, and 100%. The results demonstrated that increasing the surface roughness intensifies the bearing wear, which represents 18% and 140% of the bearing clearance for the roughness of and , respectively. Additionally, the surface roughness causes a considerable increase in the bearing wear rate. The results described a maximum wear rate of . In general, increasing the bearing load by 25% doubles the hydrodynamic pressure conditions increases friction force by 33%, and reduces lubrication film thickness by 12%. The analysis of the angle of deflection, and , shows that the moment and the degree of misalignment tend to increase significantly with the increase in the magnitude of the angle . Negative angles of deflection, , produce a greater increase in the degree of misalignment and the moment. This implies a greater chance of contact with the bearing surface. In conclusion, the proposed methodology serves as a reliable tool to simultaneously evaluate key parameters on the tribological behavior of bearings that further extend their endurance and minimize wear damage.

One of the biggest problems in energy management is the impact on the environment. For this, it is necessary to propose new techniques and strategies which reduce pollution. Examples such as carbon dioxide and other greenhouse gas emissions promote an increase in the carbon footprint. This carries the search for resources from renewable sources as sunlight, wind, rain, waves, etc. From these sources, solar energy could be used in Colombia, especially the Atlantic Coast, due to high solar radiation in this region. This study is going to collect information about the advantages and disadvantages of using photovoltaic systems (PV systems) for solar energy management with a good cost-efficiency ratio. On the other hand, the development of solar energy will be studied and compared with other energy sources. In Colombia, there is a set of energy and regulatory policies around small self-generators with renewable energy sources, which can be natural or legal persons, that is, self-generators could be civilians, merchants, or small industries. Finally, it will be discussed about the energy plans as a proposal for improved energy management in the future.

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