Eventos Anais de eventos
ENCIT 2020
18th Brazilian Congress of Thermal Sciences and Engineering
A Second Law Approach for a Pure Ethanol Droplet Injection and Evaporation In a Variable Temperature Environment - Effects of Different Evaporation Models
Submission Author:
Alessandro José Truta Beserra de Lima , SP , Brazil
Co-Authors:
Alessandro José Truta Beserra de Lima, Caio Rufino, Felipe Augusto Ferreira Gomes, Waldyr Gallo
Presenter: Alessandro José Truta Beserra de Lima
doi://10.26678/ABCM.ENCIT2020.CIT20-0128
Abstract
Droplet evaporation modeling is essential to predict how fuel evaporates before the beginning of the combustion process in internal combustion engines. Evaporation time and evaporation rate are some of the variables related to this model, which allows the calculation of the droplet heat-up process through time. The application of the second law of thermodynamics highlights main sources of irreversibilities in specific processes. The purpose of this work is to show the main differences among some evaporation models known in the literature for a pure ethanol droplet injection and subsequently evaporation surrounded by typical in-cylinder gases during compression phase of a spark-ignition engine. This study is developed under the view of the second law of thermodynamics, specifically through the calculation of entropy generation. Initially, the differences between droplet evaporation models are presented, with focus on the heat-up process. Later, the differences among these models are highlighted for different air-fuel ratio conditions in terms of evaporation time, droplet penetration inside the cylinder gas, entropy generation and evaporative cooling effect, indicating details related to different injection moments during a spark-ignition engine cycle.
Keywords
Second Law of Thermodynamics, Droplet evaporation, ethanol, Direct injection
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