Mechanical Engineering ETDs

Publication Date

Spring 4-29-2020

Abstract

Combustion is one of the most difficult processes to model. Luminous flames are characteristically sooty, which creates a problem when modeling and calculating the combustion and heat transfer of the process; both of which are highly dependent on temperature and emissivity. Soot particle emissivity as well as gas contributions affect the heat transfer calculation and must be accounted for.

Thermographic phosphors (TP) are ceramic based phosphorescent materials that have a temperature dependent emission that can be exploited to obtain surface and gas temperature measurements, as well as 2D temperature maps. Emissivity knowledge is not needed to obtain temperature and is not affected by the flame radiation emissions. However, since the TP is attached to the sample and it can also float into the gas/flame, the emissivity is still needed for heat transfer and energy balance calculations.

The focus of this work is to study and measure the thermal radiation emissivity of Dysprosium doped Yttrium Aluminum Garnate (YAG:Dy) and Manganese doped Magnesium Fluorogermanate (MFG:Mn). Tests were conducted on both an Aerosol Deposited or AD (room temperature coating method that plastically deforms and bonds the particles onto the surface) and a “painted-on” (powder mixed with alcohol and brushed on the substrate) stainless steel sample.

A Sandia LED driver, with a UV LED (365nm), was used as the light source to illuminate the samples inside a Watlow heater. These samples were submitted to a temperature range of 50-550ᵒC at approximately 50ᵒC steps; the data was collected utilizing a FLIR A655 camera. The YAG:Dy temperature vs. emissivity curve is fairly stable. On the other hand, for the MFG:Mn, the emissivity decreases with temperature. For both AD samples, compared to the “painted-on” samples, a decrease in emissivity is shown which is still being investigated.

Keywords

Emissivity, Thermographic Phosphors, Aerosol Deposition, Spectral Response, Heat Transfer

Degree Name

Mechanical Engineering

Level of Degree

Masters

Department Name

Mechanical Engineering

First Committee Member (Chair)

Peter Vorobieff

Second Committee Member

Humberto Silva

Third Committee Member

Daniel Banuti

Document Type

Thesis

Language

English

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