Session: 16-01-01: Government Agency Student Poster Competition

Paper Number: 149816

149816 - Single Droplet Combustion 

Due to growing environmental concerns caused by increasing emissions output and the gradual decline of fossil fuels, alternative fuels have been an attractive topic of study. Biofuels are often derived from plants, algae material, or animal waste. The characteristics of biofuel are dependent on the composition of the feedstock. The varying compositions of algae oil and vegetable oil can have different effects when used to produce biofuel. Using alternative fuels as additives has also been a topic of study. Research has focused on the use of jet fuel, diesel, and ethanol with various blends of alternative fuels. Understanding the combustion behavior of alternative fuels is vital for combustion system optimization and application.

Single droplet combustion experiments are a beneficial and cost-effective way to evaluate combustion characteristics. Atomization is a vital step of the fuel in the combustion process in many applications. Single droplet combustion experiments aid in a better understanding of this step as well. Various methods have been employed in previous studies for single droplet combustion experiments such as spark ignition, drop method, and suspended method. For most experiments, the D^2 law of combustion is employed to describe the behavior of the combusting droplets. The law states that droplets are spherically symmetric and that the droplet diameter decreases with time.  

This study implements the suspended droplet method to study the single droplet combustion characteristics of various fuel types. A droplet was dispensed from a micro syringe onto the intersection of 16um silicon carbide fibers. The low thermal conductivity of the fibers ensures that they do not interfere with the burning process. The droplet was ignited using two 36-guage kanthal hotwire loops that were placed on both sides of the suspended droplet. The hotwire loops are heated using a DC power supply and are attached to linear actuators. The linear actuators serve as the retraction system to ensure that hot wire loops are moved away from the droplet after ignition occurs. The sequence of events was controlled using an Arduino UNO microcontroller. The images were imported into Spotlight image processing software for analysis.

Results obtained from this experiment include the initial diameter, burn time, burning rate, and overall combustion behavior of the droplet. These findings aid in optimizing combustion systems and understanding the combustion characteristics of the fuels being tested. The results obtained from single droplet combustion experiments are beneficial in that the same results cannot be obtained from a full-scale combustion system.

Presenting Author: Karah Powell University of Tennessee at Chattanooga

Presenting Author Biography: Karah Powell is a graduate student at the University of Tennessee at Chattanooga. She received her BS in Mechanical Engineering with departmental honors from UTC in 2021. She is currently pursuing her MS in Mechanical Engineering. She works under Dr. Yunye Shi as part of a NSF-funded project to study the single droplet combustion of alternative fuels.

Authors:

Karah Powell University of Tennessee at Chattanooga
Yunye Shi University of Tennessee at Chattanooga