Sebastián Heredia Quintana

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.

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.