DOI

10.17077/etd.umadx8wr

Document Type

Thesis

Date of Degree

Fall 2016

Degree Name

MS (Master of Science)

Degree In

Mechanical Engineering

First Advisor

Albert Ratner

First Committee Member

James Buchholz

Second Committee Member

Shaoping Xiao

Abstract

Thermal management is a major concern of jet engine development. During flight, engine components reach extreme temperatures as a result of frictional heating due to elevated airflow velocities. Jet fuel is used as a coolant to dissipate heat throughout the engine. This cooling process induces temperature and pressure increases within the fuel. At temperatures above 325°F, hydrocarbon fuels start to become thermally unstable, leading to the formation of solid deposits, known as coke. This paper outlines an experimental study that was conducted to further examine the coking mechanism. Specifically, a complete experimental setup and procedure was designed to simulate coke deposit formation in a controlled laboratory environment. Fuel was thermally stressed up to 330°C at 10 Bar for approximately 6 hours. Tests were conducted using plain Jet-A fuel and Jet-A fuel with 0.1% carbon nanoparticle and nanotube additives. Deposit formation on stainless steel samples were analyzed using Scanning Electron Microscopy imaging. Results showed that the introduction of nano-additives into the fuel yielded less deposit formation and build up on stainless steel surfaces. Both nanoparticles (100 nm diameter) and nanotubes (8 – 15 nm diameter, 0.5 – 2 μm length) were found to be effective at suppressing coke deposits above 300°C.

Public Abstract

Thermal management is a major concern of jet engine development. During flight, engine components reach extreme temperatures as a result of frictional heating due to elevated airflow velocities. In order prevent overheating, jet fuel is used as a coolant to dissipate, or absorb the heat from the engine. As the fuel absorbs the waste heat, the temperature and pressure increases. At temperatures above 325°F, hydrocarbon fuels start to become thermally unstable. Thermal stability is characterized as a fuel’s tendency to form solid deposits on fuel lines, nozzles, intake valves, and other engine components. This process is also referred to as coking, and is driven by complex chemical mechanisms that are triggered by increased temperatures.

This paper outlines an experimental study that was conducted to further examine the coking mechanism. Specifically, a complete experimental setup and procedure was designed to simulate coke deposit formation in a controlled laboratory environment. Fuel was thermally stressed up to 330°C at 10 Bar for approximately 6 hours. Tests were conducted using plain Jet-A fuel and Jet-A fuel with 0.1% carbon nanoparticle and nanotube additives. Results showed that the introduction of nano-additives into the fuel yielded less deposit formation and build up on stainless steel surfaces. A reduction in deposit formation would lead to reduced maintenance costs and improved operation for military and commercial jet engines.

Pages

x, 60 pages

Bibliography

Includes bibliographical references (pages 59-60).

Copyright

Copyright © 2016 Matthew James Panzer

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