A shock-tube facility consisting of two, single-pulse shock tubes for the study of fundamental processes related to gas-phase chemical kinetics and the formation and reaction of solid and liquid aerosols at elevated temperatures is described. Recent upgrades and additions include a new high-vacuum system, a new gas-handling system, a new control system and electronics, an optimized velocity-detection scheme, a computer-based data acquisition system, several optical diagnostics, and new techniques and procedures for handling experiments involving gas/powder mixtures. Test times on the order of 3 ms are possible with reflected-shock pressures up to 100 atm and temperatures greater than 4000 K. Applications for the shock-tube facility include the study of ignition delay times of fuel/oxidizer mixtures, the measurement of chemical kinetic reaction rates, the study of fundamental particle formation from the gas phase, and solid-particle vaporization, among others. The diagnostic techniques include standard differential laser absorption, FM laser absorption spectroscopy, laser extinction for particle volume fraction and size, temporally and spectrally resolved emission from gas-phase species, and a scanning mobility particle sizer for particle size distributions. Details on the set-up and operation of the shock tube and diagnostics are given, the results of a detailed uncertainty analysis on the accuracy of the test temperature inferred from the incident-shock velocity are provided, and some recent results are presented.

Microscale truss architectures provide high mechanical strength, light weight, and open porosity in polymer sheets. Liquid evaporation and transport of the resulting vapor through truss voids cool nearby surfaces. Thus, microtruss materials can simultaneously prevent mechanical and thermal damage. Assessment of promise requires quantitative understanding of vapor transport through microtruss pores for realistic heat loads and latent heat carriers. Pore size may complicate exegesis owing to vapor rarefaction or surface interactions. This paper quantifies the nonboiling evaporative cooling of a flat surface by water vapor transport through two different hydrophobic polymer membranes, 112–119μm (or 113–123μm) thick, with microtruss-like architectures, i.e., straight-through pores of average diameter of 1.0–1.4μm (or 12.6–14.2μm) and average overall porosity of 7.6% (or 9.9%). The surface, heated at 1350±20Wt∕m2 to mimic human thermal load in a desert (daytime solar plus metabolic), was the bottom of a 3.1cm inside diameter, 24.9cm3 cylindrical aluminum chamber capped by the membrane. Steady-state rates of water vapor transport through the membrane pores to ambient were measured by continuously weighing the evaporation chamber. The water vapor concentration at the membrane exit was maintained near zero by a cross flow of dry nitrogen (velocity=2.8m∕s). Each truss material enabled 13–14°C evaporative cooling of the surface, roughly 40% of the maximum evaporative cooling attainable, i.e., with an uncapped chamber. Intrinsic pore diffusion coefficients for dilute water vapor (<10.4mole%) in air (P total ∼112,000Pa) were deduced from the measured vapor fluxes by mathematically disaggregating the substantial mass transfer resistances of the boundary layers (∼50%) and correcting for radial variations in upstream water vapor concentration. The diffusion coefficients for the 1.0–1.4μm pores (Knudsen number ∼0.1) agree with literature for the water vapor-air mutual diffusion coefficient to within ±20%, but for the nominally 12.6–14.2μm pores (Kn ∼0.01), the diffusion coefficient values were smaller, possibly because considerable pore area resides in noncircular, i.e., narrow, wedge-shaped cross sections that impede diffusion owing to enhanced rarefaction. The present data, parameters, and mathematical models support the design and analysis of microtruss materials for thermal or simultaneous thermal-and-mechanical protection of microelectromechanical systems, nanoscale components, humans, and other macrosystems.

He received a Ph.D. in Mechanical Engineering from the Massachusetts Institute of Technology [2007] where he held a research assistantship at MIT's Institute for Soldier Nanotechnologies (ISN). At MIT he invented a new nano-enabled garment to provide simultaneous ballistic and thermal protection to infantry soldiers. Dr. Traum also earned his master's degree in Mechanical Engineeringwith a focus on Cryogenics from MIT in 2003 and two bachelor's degrees from the University of California, Irvine in 2001: one in mechanical engineering and the second in aerospace engineering. In addition, he attended the University of Bristol, UK as a non-matriculating visiting scholar where he completed an M.Eng thesis in the Department of Aerospace Engineering in 2000 on low-speed rotorcraft control. Prior to his appointment at MSOE, Dr. Traum was a founding faculty member of the Mechanical and Energy Engineering Department at the University of North Texas where he established an externally-funded researcher incubator that trained undergraduates how to perform experimental research and encouraged their matriculation to graduate school. Dr. Traum also serves as the founding Chief Technology Officer at EASENET, Inc., a start-up renewable energy company he co-founded with his former students to commercialize residential scale waste-to-energy biomass processor systems.

The analytical model of Carey is extended and clarified for modeling Tesla turbine performance. The extended model retains differentiability, making it useful for rapid evaluation of engineering design decisions. Several clarifications are provided including a quantitative limitation on the model’s Reynolds number range; a derivation for output shaft torque and power that shows a match to the axial Euler Turbine Equation; eliminating the possibility of tangential disk velocity exceeding inlet working fluid velocity; and introducing a geometric nozzle height parameter. While nozzle geometry is limited to a slot providing identical flow velocity to each channel, variable nozzle height enables this velocity to be controlled by the turbine designer as the flow need not be choked. To illustrate the utility of this improvement, a numerical study of turbine performance with respect to variable nozzle height is provided. Since the extended model is differentiable, power sensitivity to design parameters can be quickly evaluated—a feature important when the main design goal is maximizing measurement sensitivity. The derivatives indicate two important results. First, the derivative of power with respect to Reynolds number for a turbine in the practical design range remains nearly constant over the whole laminar operating range. So, for a given working fluid mass flow rate, Tesla turbine power output is equally sensitive to variation in working fluid physical properties. Second, turbine power sensitivity increases as wetted disk area decreases; there is a design trade-off here between maximizing power output and maximizing power sensitivity.

Design processes and analytical modeling are presented showing creation of a low-cost concentrating photovoltaic-thermoelectric (PV/TE) hybrid power system for research and laboratory teaching built using a small upcycled satellite dish. Today, concentrated solar hybrid PV/TE systems are drawing significant research attention and funding investment. However, the literature lacks examples of how this cutting-edge energy technology can be made accessible at low cost for STEAEM education at universities, vocational institutions, and high schools. By applying Energy Engineering Laboratory Module (EELM™) design principles and pedagogy, a process is presented to make this technology easily accessible at low cost. The concentrating solar hybrid PV/TE system presented here is divided into four subsystems: 1) a concentrator, 2) a PV/TE generator, 3) data acquisition, and 4) a cooling system. The key engineering decisions governing the design for each sub-system are described. In addition, a thermodynamic analysis is presented to predict the on-sun steady-state temperature profile of the PV/TE generator at the focus of the concentrator and to determine how much electrical power it will produce. The concentrator used is a salvaged miniature satellite dish, which is coated with mirrored tape to reflect sunlight upon a focal point. Scavenged at no cost, the satellite dish is a sectioned paraboloid of rotation offset from the vertex and the axis of symmetry. However, which paraboloid section the dish represents is unknown. A technique is presented to find the focal point and to use this information to correctly position a shadow-casting gnomon to ensure proper on-sun alignment. A method to experimentally confirm the focal location and size the PV is also provided. A key research question for solar concentrating hybrid PV/TE power systems at this size scale is whether it is better to actively cool the TE cold side via forced convection or simply allow cooling via natural convection. The thermodynamic heat balance analysis presented to address this question finds that while forced convection does better cool the PV module, increasing its efficiency and power output, the parasitic energy expenditure of the cooling fan far exceeds the additional power produced. It is therefore more beneficial to rely on natural convection on the TE cold side to maximize power production of the overall PV/TE module. Two experimental apparatuses were built consisting of a PV module backed by TE generators and instrumented with thermocouples to determine the internal temperature gradient while multi-meters read steady-state PV and TE power output. A halogen lamp placed at various distances from this array approximates concentrated sunlight, which is measured via pyranometer. These experiments validate conclusions drawn from the theoretical model.

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Texas (UNT) where he directs the research activities of the Thermal Fluid Sciences Group @ UNT . Dr. Traum earned his doctorate in mechanical engineering at the Massachusetts Institute of Technology (MIT) through MIT's Institute for Soldier Nanotechnologies where his research focused on nanotechnology systems integration with emphasis on thermal management for the dismounted soldier. Dr. Traum holds a master's degree in mechanical engineering from MIT and two bachelor's degrees from the University of California, Irvine: one in mechanical engineering and the second in aerospace engineering. He also attended the University of Bristol, UK as a non-matriculating visiting scholar where he completed an M.Eng thesis in the Department of Aerospace Engineering.

Laminar natural convection heat transfer from the vertical surface of a cylinder is a classical subject, which has been studied extensively. Furthermore, this subject has generated some recent interest in the literature. In the present investigation, numerical experiments were performed to determine average Nusselt numbers for isothermal vertical cylinders (103 < RaL < 109, 0.5 < L/D <10, and Pr = 0.7) situated on an adiabatic surface in a quiescent ambient environment which will allow for plume growth. Results will be compared with commonly used correlations and a new average Nusselt number correlation will be presented. Furthermore, the limit for which the heat transfer results for a vertical flat plate may be used as an approximation for the heat transfer from a vertical cylinder will be investigated.