Abstract
The objective of this study was to compare the injection and spray characteristics of water with n-heptane using a port fuel injection (PFI) system. In this study, the injection pressure was changed to 0.3–0.9 Mpa and the energizing duration was changed to 0.5–4 ms. To investigate spray characteristics, the injection quantities of n-heptane and water were measured. Macroscopic spray characteristics were determined through spray visualization. The Sauter mean diameter (SMD) and velocity of spray droplets were measured with a phase Doppler anemometry (PDA) experiment. Spray tip penetration, spray angle, SMD of droplets, and spray droplet velocity were compared. As the injection pressure increased, the injection quantity and the droplets velocity increased. However, the spray tip penetration, SMD of the droplet, and the spray angle decreased. The increase in energizing duration led to an increase in the injection quantity without affecting other spray characteristics. The higher density of water also increased injection quantity, resulting in a decrease in spray tip penetration and increases of SMD and velocity of spray droplets due to high viscosity and surface tension of water.
Highlights
Declining oil reserves and increasingly stringent emissions regulations call for new solutions for internal combustion engine manufacturers
Researchers have tried to solve the problem using a variety of methods, including cooling exhaust gas recirculation (EGR), rich mixture, and fuel with a high octane number [1,2,3,4,5]
When the injection pressure was increased from 0.3 MPa to 0.9 MPa, the injection quantity of water and n-heptane increased to 75.3% and 73.2%, respectively, regardless
Summary
Declining oil reserves and increasingly stringent emissions regulations call for new solutions for internal combustion engine manufacturers. Manufacturers have produced engines by adopting alternative fuel applications, miniaturization, direct injection, and overcharging for conventional engines. The compacting and overcharging of the engine are expected to improve the overall engine efficiency by about 16%, with effects such as pumping loss, weight loss, and reduced friction loss [1]. Overcharging is caused by the problem of increasing pressure and temperature in the cylinder due to abnormal combustion and ignition instability, called knocking. To solve this problem, the spark timing can be adjusted to lower the peak pressure and temperature. Excessive use of this method is limited because it leads to a significant reduction in combustion stability and fuel economy, which adversely affects engine efficiency and power. Researchers have tried to solve the problem using a variety of methods, including cooling exhaust gas recirculation (EGR), rich mixture, and fuel with a high octane number [1,2,3,4,5]
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