Publication Date

5-2010

Type of Culminating Activity

Thesis

Degree Title

Master of Science in Mechanical Engineering

Department

Mechanical and Biomechanical Engineering

Major Advisor

Donald G. Plumlee, Ph.D.

Abstract

This thesis details the design and construction of a Low Temperature Co-Fired Ceramic (LTCC) micro combustion system. The design of the combustor requires a detailed analysis of the flame’s operational properties and stability. To this end, an analytic model was created to address these concerns. These results were used in conjunction with a detailed numerical analysis to determine the stable operating range of the combustors. The combustion of gaseous fuels requires a device with a lower bound on the channel feature size. This lower limit for combustion corresponds to the minimum quenching distance of the specific fuel being used and usually corresponds to the upper end of silicon MEMs processing techniques and the lower end of meso-scale production processes. This millimeter size range represents the normal feature size range for the LTCC tape system. A potential material imposed restriction to using LTCC is the relatively low temperature operating range when compared to the adiabatic flame temperatures encountered in the combustion of gaseous fuels.

To address this concern an analytic model of the heat transfer from a simple straight channel device is presented. This model allows for the analysis of the thermal loads in the substrate as well as provides insight into the effects of the channel geometry on the stability of the flame. Several experimental devices were designed and tested in accordance with the predictions of the analytic model. These devices have similar geometric configurations with different characteristic lengths to explore the feasible operating regimes of the LTCC micro combustor. This allows for the validation of the flame stability margins and heat transfer properties predicted by the analytic model.

Infrared imaging allows for the mapping of the device surface temperature and provides a correlation mechanism to the analytic model. The results of the experimental testing show the same trending characteristics predicted by the analytic analysis. However, a detailed numerical analysis is needed to fully capture the quantitive power production capabilities of the device.

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