A. James Clark School of Engineering

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Author: search.filters.author.Kommer, Eric

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    Forced Convective Boiling via Infrared Thermography
    (2012) Kommer, Eric; Kim, Jungho; Mechanical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Multiphase heat transfer is an important mechanism across wide variety of engineering disciplines. The prediction of the heat transfer rate as a function of flow conditions and temperature has been based almost exclusively on experimentally derived correlations. The quality of these correlations depends on the accuracy and resolution of the measurement technique. In addition to the complexities of flow boiling phenomenon in earth gravity, engineering design of space systems requires knowledge of any gravity dependence for heat transfer characteristics. Current research has shown significant variation in the heat transfer characteristics during pool boiling as a function of gravity magnitude. Research into flow boiling in variable gravity environments is extremely limited at this time, but necessary before multiphase systems can be designed for space. The objective of this study is to develop, validate, and use a unique infrared thermometry method to quantify the heat transfer characteristics of flow boiling in earth gravity, prior to use of the apparatus in variable gravity environments. This new method allows high spatial and temporal resolution measurements, while simultaneously visualizing the flow phenomenon. Validation of this technique will be demonstrated by comparison to accepted correlations for single and multiphase heat transfer in earth gravity environments.
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    VARIATIONS OF ENGINE PARTICULATE MATTER IN A MINIATURE DILUTION TUNNEL
    (2003-12-12) Kommer, Eric; Buckley, Steven G; Mechanical Engineering
    Measurement of diesel and spark ignition engine particulate emissions is of wide interest due to current research demonstrating that inhalation of nanoparticles may cause serious health problems. Both experimental and computational methods were used to investigate fluid and particle flows through a miniature dilution tunnel similar to those commonly used to sample particulate emissions from engines to help explain observed varabilities and bias, and to improve the repeatability of results. Laser Doppler Velocimetry, flow visualization, and a commercial CFD code were used to measure the flow field inside the apparatus. Slugs of NOx calibration gas and a high speed NOx concentration meter were used to measure mean velocities through the apparatus. An artificial aerosol generator was used in conjunction with a Scanning Mobility Particle Sizer (SMPS) to determine how tunnel geometry affects particle size distributions. These results were compared to a Monte Carlo type numerical simulation, accounting for Brownian motion and fluctuating turbulent velocities.