This work is an experimental study for the measurement of ignition delay characteristics of burning fuel sprays in cylindrical combustion chambers. It is carried out on hot air and high pressure. The objective of the study is to investigation the effect of hot air temperature and a well as high pressure on ignition delay of diesel fuel sprays.
The effect of blending of n-Pentane with pure diesel was investigated. An experimental set up was design for this purpose with the emphasis on optical method for measurement of ignition delay at various pressures. The results presented here show that ignition delay of diesel fuel spray decreases with increase in the temperature and pressure of hot air. Results also show the effect of methyl group being more dominant at low ignition temperatures and that of alkyl group being more dominant at higher temperature.
Blending of n-pentane with diesel fuel, increase its ignition delay at low ignition temperatures. However, as the concentration of blending fuel was increased beyond 30%, the ignition temperature increase. Ignition temperature for 40% pentane blends is much higher that the pure diesel.
Table of Contents
INTRODUCTION
1.1 Diesel Combustion
1.2 Ignition Delay
1.2.1 Factors Affecting Ignition Delay:
1.2.2 Chemical Factors
1.3 Diesel Fuel Chemistry
1.3.1 Different properties of Diesel fuel are discussed below
1.5 Test Procedure
RESULTS AND DISCUSSION
CONCLUSION AND FUTURE INVESTIGATIONS
REFERENCES
Research Objectives and Key Topics
The primary objective of this study is to experimentally investigate the ignition delay characteristics of diesel fuel sprays under varying high-pressure and high-temperature conditions in a cylindrical combustion chamber. Furthermore, the research examines the impact of blending diesel with n-pentane on these ignition characteristics, utilizing an optical measurement method to gain deeper insights into combustion performance.
- Analysis of ignition delay in direct injection diesel engines.
- Evaluation of the effects of hot air temperature and high pressure on fuel spray combustion.
- Investigation into the impact of n-pentane blending ratios on ignition behavior.
- Comparative study between measured data and traditional analytical models (Wolfer and Stringer).
Excerpt from the Book
1.1 Diesel Combustion
The combustion process is neither completely non-premixed (diffusion) nor premixed. On the contrary the initial portion of the fuel being injected is vaporized and forms a premixed mixture, in a period known as ignition delay.
Premixed burning takes place with the instantaneous rise in the flame temperature and consequently, the maximum rate of heat release. It is burning phase during which although only 20% of total fuel injected is burnt but nearly 50% of NOx are formed tie to the high temperature during this phase. This premixed burning at the end of ignition delay is followed by homogeneous diffusion burning at different location of combustion chamber.
This burning phase is followed by heterogeneous diffusion burning during which individual droplets continue to burn and eventually end the combustion process well advance in the exhaust stroke.
Summary of Chapters
INTRODUCTION: Provides an overview of diesel engine efficiency and the challenges posed by modern emission regulations, emphasizing the importance of understanding combustion processes.
1.1 Diesel Combustion: Explains the hybrid nature of the combustion process, detailing the stages from ignition delay to premixed and diffusion burning.
1.2 Ignition Delay: Defines ignition delay as the time lag between injection and ignition, categorizing it into physical and chemical components.
1.2.1 Factors Affecting Ignition Delay:: Tabulates various engine variables such as injection pressure, timing, and temperature, and their specific impacts on the delay period.
1.2.2 Chemical Factors: Discusses fuel ignition quality, focusing on Cetane number, Cetane index, and the role of hydrocarbon composition.
1.3 Diesel Fuel Chemistry: Details the complex mixture of hydrocarbons in diesel and how molecular structure influences properties like boiling point, density, and viscosity.
1.3.1 Different properties of Diesel fuel are discussed below: Outlines specific physical characteristics of diesel components, including heating value and cetane number variations.
1.5 Test Procedure: Describes the experimental setup and the optical measurement process used to determine ignition delay in the combustion chamber.
RESULTS AND DISCUSSION: Compares experimental findings with theoretical models and analyzes the impact of n-pentane blending on ignition performance.
CONCLUSION AND FUTURE INVESTIGATIONS: Summarizes the key findings regarding the influence of pressure, temperature, and blending ratios on ignition delay.
REFERENCES: Lists the academic literature and technical papers cited throughout the study.
Keywords
Ignition delay, Diesel engine, Combustion chamber, n-Pentane blending, High pressure, Hot air temperature, Optical method, Cetane number, Hydrocarbon, Fuel injection, Arrhenius equation, Premixed burning, Diffusion burning, Emission regulation, Combustion analysis
Frequently Asked Questions
What is the core focus of this research?
The research investigates the ignition delay characteristics of diesel fuel sprays when subjected to high pressures and temperatures, specifically in a cylindrical combustion chamber.
What are the central thematic fields addressed in the paper?
The study focuses on diesel engine combustion, fuel chemistry, the physics of ignition delay, and the effects of alternative fuel blending on combustion quality.
What is the primary goal or research question?
The goal is to determine how hot air temperature, high pressure, and the addition of n-pentane influence the ignition delay of diesel fuel, using an optical measurement technique.
Which scientific methods were applied in this study?
The study uses an experimental approach involving a cylindrical combustion chamber, air compressors, and optical sensors to measure ignition delay, followed by comparative analysis against known formulas like Wolfer and Stringer.
What topics are covered in the main section?
The main sections cover diesel combustion mechanics, the factors influencing ignition delay (physical and chemical), diesel fuel chemistry, and the experimental results of blending diesel with n-pentane.
Which keywords best characterize this work?
Keywords include Ignition delay, Diesel engine, n-Pentane, High pressure, Combustion analysis, Cetane number, and Fuel injection.
Why does the ignition delay decrease as the temperature and pressure of the hot air increase?
Higher temperatures and pressures accelerate the physical and chemical processes, such as fuel vaporization and chemical reaction rates, which lead to earlier ignition.
How does the addition of n-pentane affect the ignition delay of diesel at different temperatures?
At lower temperatures, n-pentane blending increases the ignition delay, while at higher temperatures, it may result in shorter delay times compared to pure diesel.
- Citar trabajo
- Ritu Gaur (Autor), 2019, Ignition Delay at Various High Pressures. An Experimental Study, Múnich, GRIN Verlag, https://www.grin.com/document/504907
