Effect of Heat Flux Ratio on Two-Dimensional Horizontal Channel Flow

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76088/1/AIAA-9125-292.pd

Effect of Heat Flux Ratio from both Side-walls on Thermal-fluid Flow in Channel

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76163/1/AIAA-2002-2873-281.pd

Enhancement of Methane Concentration by Removing Contaminants from Biogas Mixtures Using Combined Method of Absorption and Adsorption

We report a laboratory scale combined absorption and adsorption chemical process to remove contaminants from anaerobically produced biogas using cafeteria (food), vegetable, fruit, and cattle manure wastes. Iron oxide (Fe2O3), zero valent iron (Feo), and iron chloride (FeCl2) react with hydrogen sulfide (H2S) to deposit colloidal sulfur. Silica gel, sodium sulfate (Na2SO4), and calcium oxide (CaO) reduce the water vapour (H2O) and carbon dioxide (CO2). It is possible to upgrade methane (CH4) above 95% in biogas using chemical or physical absorption or adsorption process. The removal efficiency of CO2, H2S, and H2O depends on the mass of removing agent and system pH. The results showed that Ca(OH)2 solutions are capable of reducing CO2 below 6%. The H2S concentration was reduced to 89%, 90%, 86%, 85%, and 96% for treating with 10 g of FeCl2, Feo (with pH), Fe2O3, Feo, and activated carbon, respectively. The H2O concentration was reduced to 0.2%, 0.7%, 0.2%, 0.2%, and 0.3% for treating raw biogas with 10 g of silica gel and Na2SO4 for runs R1, R2, R3, R4, and R5, respectively. Thus, given the successful contaminant elimination, the combined absorption and adsorption process is a feasible system for biogas purification

Thermal-Fluid Flow Transport Phenomenon over Slot-Perforated Flat Surface in Narrow Channel

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76171/1/AIAA-2006-3596-641.pd

Thermal-fluid transport phenomena in an axially rotating flow passage with twin concentric orifices of different radii

This paper investigates the thermal fluid-flow transport phenomena in an axially rotating passage in which twin concentric orifices of different radii are installed. Emphasis is placed on the effects of pipe rotation and orifice configuration on the flow and thermal fields, i.e. both the formation of vena contracta and the heat-transfer performance behind each orifice. The governing equations are discretized by means of a finite-difference technique and numerically solved for the distributions of velocity vector and fluid temperature subject to constant wall temperature and uniform inlet velocity and fluid temperature. It is found that: (i) for a laminar flow through twin concentric orifices in a pipe, axial pipe rotation causes the vena contracta in the orifice to stretch, resulting in an amplification of heat-transfer performance in the downstream region behind the rear orifice, (ii) simultaneously the heat transfer rate in the area between twin orifice is intensified by pipe rotation, (iii) the amplification of heat transfer performance is affected by the front and rear orifice heights. Results may find applications in automotive and rotating hydraulic transmission lines and in aircraft gas turbine engines. Copyright © 2005 John Wiley & Sons, Ltd.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34229/1/1181_ftp.pd

Thermal-Fluid Flow Transport Phenomenon over Slot-Perforated Flat Plates Placed in Narrow Channel

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76151/1/AIAA-25872-119.pd

FLUID FLOW CHARACTERISTICS AROUND A PAIR OF DIAMOND-SHAPED CYLINDERS IN SIDE-BY-SIDE AND TANDEM ARRANGEMENTS

ABSTRACT The present study deals with unsteady laminar fluid flow phenomena around a pair of diamond-shaped cylinders in free stream. Emphasis is placed on the effects of the Reynolds number, Re, and the ratio of cylinder separation distance to length of diamond-shaped cylinder, s/d, on the flow patterns in side-by-side and tandem arrangements. The Navier-Stokes equations are discretized using finite difference method to determine the time history of velocity vector in the flow field. The Reynolds numbers, Re, is ranged from 30 to 300 and gap spacing, s/d, is varied from 0.0 to 2.5 for side-by-side and 0.0 to 5.0 for tandem, respectively. The results are compared with the experimental results with the aid of flow visualization method. The study discloses that (i) the generations of Karman vortex streets behind the diamond-shaped cylinders are intensified with an increase in the Reynolds number, (ii) the categorized flow patterns in the wake region of the diamondshaped islands are affected by s/d, and (iii) the vortex shedding frequency in the wake of diamond-shaped cylinders depends on both the gap spacing and the formation of the vortices

Stacked Packaging Laminar-Convection-Cooled Printed Circuit Using the Entropy Generation Minimization Method

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76567/1/AIAA-30451-562.pd

Synchrotron-radiation-stimulated etching of polydimethylsiloxane using XeF2 as a reaction gas

Synchrotron-radiation-stimulated etching of silicon elastomer polydimethylsiloxane using XeF2 as an etching gas is demonstrated

Detection of Pulsed X-ray Emission from The Fastest Millisecond Pulsar PSR B1937+21 with ASCA

We have detected pulsed X-ray emission from the fastest millisecond pulsar known, PSR B1937+21 (P=1.558 msec), with ASCA. The pulsar is detected as a point source above $\sim 1.7$ keV, with no indication of nebulosity. The source flux in the 2--10 keV band is found to be $f = (3.7\pm 0.6) \times 10^{-13}$ erg s$^{-1}$ cm$^{-2}$, which implies an isotropic luminosity of $L_{\rm x} = 4 \pi D^2 f \sim (5.7\pm 1.0) \times 10^{32} ~(D/3.6 {\rm kpc})^2$ erg s$^{-1}$, where D is the distance, and an X-ray efficiency of $\sim 5 \times 10^{-4}$ relative to the spin-down power of the pulsar. The pulsation is found at the period predicted by the radio ephemeris with a very narrow primary peak, the width of which is about 1/16 phase ($\sim 100 \mu$s), near the time resolution limit ($61 \mu$s) of the observation. The instantaneous flux in the primary peak (1/16 phase interval) is found to be ($4.0\pm 0.8) \times 10^{-12}$ erg s$^{-1}$ cm$^{-2}$. Although there is an indication for the secondary peak, we consider its statistical significance too low to claim a definite detection. The narrow pulse profile and the detection in the 2--10 keV band imply that the X-ray emission is caused by the magnetospheric particle acceleration. Comparison of X-ray and radio arrival times of pulses indicates, within the timing errors, that the X-ray pulse is coincident with the radio interpulse.Comment: 14 pages with 5 figures. Ap. J. in pres