Energy transition to renewable sources and more efficient technologies is needed for sustainable development. Although this transition is expected to take a longer time in developing countries, strategies that have been widely explored by the international academic community, such as advanced combustion modes and microgeneration, could be implemented more easily. However, the implementation of these well-known strategies in developing countries requires in-depth research because of the specific technical, environmental, social, and economic conditions. The present research relies on the use of biogas-fueled HCCI engines for power generation under sub-atmospheric conditions provided by high altitudes above sea level in Colombia. A small air-cooled commercial Diesel engine was modified to run in HCCI combustion mode by controlling the air–biogas mixture temperature using an electric heater at a high speed of 1800 revolutions per minute. An experimental setup was implemented to measure and control the most important experimental variables, such as engine speed, biogas flow rate, intake temperature, crank angle degree, intake pressure, NOx emissions, and in-cylinder pressure. High intake temperature requirements of around 320 ${}^{\circ }$C were needed to achieve stable HCCI combustion; the maximum net indicated mean effective pressure (IMEPn) was around 1.5 bar, and the highest net indicated efficiency was close to $32\%$. Higher intake pressures and the addition of ozone to the intake mixture were numerically studied as ways to reduce the intake temperature requirements for stable HCCI combustion and improve engine performance. These strategies were studied using a one-zone model along with detailed chemical kinetics, and the model was adjusted using the experimental results. The simulation results showed that the addition of 500 ppm of ozone could reduce the intake temperature requirements by around 50 ${}^{\circ }$C. The experimental and numerical results achieved in this research are important for the design and implementation of HCCI engines running biogas for microgeneration systems in developing countries which exhibit more difficult conditions for HCCI combustion implementation.

One of the key factors of the current energy transition is the use of hydrogen (H₂) as fuel in energy transformation technologies. This fuel has the advantage of being produced from the most primary forms of energy and has the potential to reduce carbon dioxide (CO₂) emissions. In recent years, hydrogen or hydrogen-rich mixtures in internal combustion engines (ICEs) have gained popularity, with numerous reports documenting their use in spark ignition (SI) and compression ignition (CI) engines. Homogeneous charge compression ignition (HCCI) engines have the potential for substantial reductions in nitrogen oxides (NOx) and particulate matter (PM) emissions, and the use of hydrogen along with this kind of combustion could substantially reduce CO₂ emissions. However, there have been few reports using hydrogen in HCCI engines, with most studies limited to evaluating technical feasibility, combustion characteristics, engine performance, and emissions in laboratory settings at sea level. This paper presents a study of HCCI combustion using hydrogen in a stationary air-cooled Lombardini 25 LD 425-2 modified diesel engine located at 1495 m above sea level. An experimental phase was conducted to determine the intake temperature requirements and equivalence ratios for stable HCCI combustion. These results were compared with previous research carried out at sea level. To the best knowledge of the authors, this is the first report on the combustion and operational limits for an HCCI engine fueled with hydrogen under the mentioned specific conditions. Equivalence ratios between 0.21 and 0.28 and intake temperatures between 188 °C and 235 °C effectively achieved the HCCI combustion. These temperature values were, on average, 100 °C higher than those reported in previous studies. The maximum value for the indicated mean effective pressure (IMEPn) was 1.75 bar, and the maximum thermal efficiency (ITEn) was 34.5%. The achieved results are important for the design and implementation of HCCI engines running solely on hydrogen in developing countries located at high altitudes above sea level.

This study presents the implementation of a micro-generation system and its operation procedure, based on a dual fuel diesel engine using natural gas as the primary fuel and conventional diesel as the pilot fuel. On the other hand, the evaluation and validation results by experimental testing of a model according to International Energy Agency—IEA—Annex 42, applied to dual fuel diesel micro-cogeneration system, are also presented. The control procedure for experimental operation depends of both inputs’ electric power generation demand and desired substitution level due a given natural gas availability. The heat recovery system of the micro-generation system uses a gas–liquid compact heat exchanger that was selected and implemented, where wasted heat from exhaust gases was transferred to liquid water as a cool fluid. Effective operation engine performance was determined by measurement of masses’ flow rate such as inlet air, diesel and natural gas, and also operation parameters such as electric power generation and recovered thermal power were measured. Electric power was generated by using an electric generator and then dissipated as heat by using an electric resistors bank with a dissipation capacity of $18\mathrm{kW}$. Natural gas fuel was supplied and measured by using a sonic nozzle flowmeter; in addition, natural gas composition was close to $84.7\%$ ${\mathrm{CH}}_4$, $0.74\%$ ${\mathrm{CO}}_2$ and $1.58\%$ ${\mathrm{N}}_2$, with the rest of them as higher hydrocarbons. The highest overall efficiency (electric efficiency plus heat recovery efficiency) was $52.3\%$ at $14.4$ kW of electric power generation and $0\%$ of substitution level. Several substitution levels were tested at each engine electric power generation, obtaining the maximum substitution level of $61\%$ at $17.7$ kW of electric power generation. Finally, model prediction results were closed to experimental results, both stationary and transient. The maximum error presented was close to $20\%$ associated to thermal efficiency. However, errors for all other variables were lower than $10\%$ for most of micro-cogeneration system operation points.

The growth of the automotive fleet in cities and the imminent depletion of traditional hydrocarbon deposits mean that research in the field of internal combustion engines focuses on generating strategies and developing technologies that allow a reduction in fuel consumption and pollutants emissions. The use of numerical models for simulation is an important tool for both researchers and designers as they allow to approach the performance of the engines under certain operating conditions without incurring in the expense involved in experimental studies and allow analyzing multiple phenomena that occur during combustion that are not easily evaluable from experimental measurements. In this study, a zero-dimensional two zones model which separates the combustion chamber into burned and unburned gases was developed seeking to study the combustion process in ignition engines using gaseous renewable fuel (biogas), using the Law of Wiebe and the chemical equilibrium to simulate the combustion process and the Woschni's semi-empirical correlation for heat transfer. The model is calibrated with information obtained from a high compression ratio (15.5: 1) engine of the combustion and thermal machines laboratory of the University of Antioquia. The main variables of combustion and engine performance (heat release rate, maximum pressure, indicated work, among others) were compared with the results of the model, as well as the emissions generated from CO and NO. There are low errors between the experimental values predicted by the model, with errors less than 10% for the main variables, except for the indicated work, with errors of 27%, and errors between 18% and 49% for the generated emissions, obtaining the highest errors as the degree of load of the motor increases.

Este artículo presenta los resultados de la evaluación de estrategias de análisis desarrolladas para los motores de combustión convencionales aplicadas al estudio de un motor de encendido provocado de alta relación de compresión. El motor objeto de análisis ha sido obtenido a partir de la transformación a modo encendido provocado de un motor Diesel estacionario. Se ha analizado la precisión del cálculo del dosado relativo a partir de la composición de los gases de escape, el criterio para establecer el inicio de la combustión usando la fracción de calor liberado y el efecto del cálculo de la masa residual en el balance de energía al interior del cilindro. Los resultados sugieren que las estrategias de análisis utilizadas son aplicables a este tipo de motores, pese a tener diferencias de diseño y operacionales respecto a las tecnologías convencionales.