Title

Steam-Assisted Catalysis of n-Dodecane as a Jet Fuel Analogue in a Flow Reactor System for Hypersonic Thermal Management

Date of Award

1-1-2019

Degree Name

Ph.D. in Mechanical Engineering

Department

Department of Mechanical and Aerospace Engineering and Renewable and Clean Energy

Advisor/Chair

Advisor: Jamie Ervin

Abstract

Heat removal capacity of catalytically cracked jet fuel using supercritical n- dodecane as a jet fuel analogue in a cylindrical packed bed reactor is examined. The cracking reactions are endothermic, and can be used in the design of a potential hypersonic vehicle fuel reactor. Fuel endotherm and product distribution were examined using three catalysts: a commercially available platinum catalyst on a ceramic support matrix, cerium applied to the platinum catalyst, and cerium applied to a ceramic support. Where much previous research has used catalyst coated tubes, this study made use of a solid catalyst structure in a packed bed to distribute the catalyst throughout the fuel flow in order to provide more surface catalyst sites. The packed bed was assumed to be an ideal plug flow reactor, with catalytic reactions that are radially uniform across the reactor diameter. For some experiments, water was added to the fuel mixture prior to heating for steam assistance to the n-dodecane pyrolysis reaction in order to examine the steam effect on carbon production and endotherm. Where previous research has used either used a catalyst to aid in endothermic thermal management or has focused on water addition to pyrolysis reactors in order to reduce coke formation, this study combines these approaches. A catalyst is used to initiate endothermic reactions at lower temperatures than would be achieved by thermal cracking alone, in conjunction with steam addition to reduce coking. The packed bed catalyst configuration provides continued catalytic action even as cracking temperatures increase and thermal cracking becomes dominant, thereby enhancing chemical heat sink. The cerium catalysts out-performed the platinum catalyst both in terms of increased endotherm and decreased carbon deposition. Steam assistance proved beneficial in decreasing carbon deposition, although at the cost of decreased dodecane conversion, hence endotherm. No appreciable product selectivity was observed for steam assistance with either catalyst. Finally, the reaction constant for each catalyst-steam addition case was compared to the dodecane conversion in order to determine a relationship that can potentially be applied in designing a reactor for use in a thermal management system.

Keywords

Mechanical Engineering, Engineering, dodecanese, hypersonic, cracking, catalysis, pyrolysis, thermal management, endothermic, platinum catalyst, cerium catalyst, catalytic cracking, coking mitigation, steam assistance, fuel endotherm, chemical heat sink

Rights Statement

Copyright 2019, author

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