Robert Jennings Heinsohn

The effects of an electric field on an opposed-jet diffusion flame

The extinction of opposed-jet diffusion flames is studied under an applied electric field of varying intensity and polarity. Experiment reveals that at any particular flame composition, an electric field enables one to support flames with greater apparent flame strengths than without a field. The overall order of reaction varies with both intensity and polarity of the electric field. It is suggested that, below discharge intensity, an electric field may affect combustion kinetics by altering gas concentration gradients, or by contributing new electron molecule reactions.

A mathematical model of the opposed-jet diffusion flame: Effect of an electric field on concentration and temperature profiles

Abstract A computer simulation of an opposed-jet methane/oxygen/nitrogen diffusion flame is presented which includes a realistic set of chemical reactions and realistic transport properties. The overall continuity equation and momentum balance are modeled in an approximate manner. The predicted concentration and temperature profiles agree satisfactorily with the available experimental information. It is shown that replacing the differential equations by their finite difference forms is a convenient way to handle this kind of two point boundary condition problem. An electric field is imposed on the flame by introducing a simplified model of the “ionic wind” which neglects any effects of electrons. Under these circumstances the concentration and temperature profiles are predicted to shift toward the cathode, but most do not change appreciably in magnitude. Flames at two temperatures are studied, with concentrations of NO predicted to be much higher in the higher temperature flame. Several reactions involving NO 2 did not affect the concentration of NO calculated using only the Zeldovich mechanism.

Effect of electric fields on ducted diffusion flames

The behavior of ducted laminar and turbulent diffusion flames is influenced by de electric fields. The geometry, luminosity, velocity field, and heat transfer are examined.

Predicting solvent concentrations from coating the inside of bulk storage tanks

A technique is presented to assess health risks associated with coating the inside surface of a bulk storage tank. The technique uses a sequential box model to predict the time-varying solvent concentrations at arbitrary points inside the vessel during an ongoing coating process. Input parameters include volumetric flow rates of exhaust and makeup air, solvent threshold limit values and evaporation rates, and a set of exchange coefficients that characterize air circulation inside the vessel. This technique enables engineers to rate quantitatively the anticipated health risks of applying a combination of coatings. The technique also provides engineering managers a predictive tool to organize work schedules so that health and safety can become input parameters to an engineering enterprise.

Nonequilibrium bipolar charging of aerosol particles: Theory and experiment

Abstract A theoretical and experimental study of particle charge acquisition in a region containing unequal current densities of ions of opposite polarity (a nonequilibrium bipolar region) is presented. A continuum model of ion transport is combined with charging expressions to describe the nonequilibrium bipolar charging of aerosol particles. Experiments employing an 11-MCi 90Sr-90Y β source and electric and magnetic fields are performed to verify the calculational method. Trajectories of 50–100-μm-diameter glass beads falling through the experimental apparatus are recorded on film by a photographic technique utilizing an open aperture camera and stroboscopic light source. Predicted increases in the particle charging rate upon application of a magnetic field strength of approximately 1000 G are clearly demonstrated by experiments. Measured charging rates are in fair agreement with theory, especially in the presence of the magnetic field. This research provides a quantitative basis upon which particle charging and motion in bipolar ionic regions may be calculated.

Grinding booth for large castings

The design of a grinding booth suitable for large castings and portable hand-held grinders is recommended. Systematically studied were the air velocities within the booth as functions of the geometry of the suction ports, recirculation jets, ventilation flow rate and recirculation flow rate. The rate at which grinding particles are injected into the air from the surface of the grinding wheel was studied and described in terms of a distribution function G(θ) and the metal removal rate.

Radiation charging: a novel way to charge fine particles electrically

The purpose of this paper is to describe a scheme to electrically charge fine particles using electric and magnetic fields in conjunction with ionizing radiation. Once charged, particulate matter can be removed from the air stream by directly applying a transverse electric field. In addition, since electrostatic forces can assist filtration and wet collection systems, it may be possible to design new and improved filtration and wet scrubber systems using radiation charging. The objectives of this paper are: (1) to present expressions that predict the charge acquired by particles and (2) to present the results of preliminary experiments.

Individual accuracy in estimating plume opacity

The accuracy of individuals to estimate the opacity of black and white plumes in Visible Emission Training Programs is analyzed. The analysis includes new students and individuals returning for recertification. Following a set of drills, students generally have accuracy only slightly lower than those achieving certification. The accuracy of individuals during their initial recertification attempt is virtually the same as the accuracy six months earlier when they passed the certification test. The most important skill to reading opacity is an unshakable mental impression of plumes having 25, 50 and 75 percent opacity.

CONTROL OF FUGITIVE DUST BY WINDBREAKS

ABSTRACT Fugitive dust generated by industrial haul roads can be reduced by windbreaks placed upwind or downwind of the road. For an elementary wind profile downwind of a windbreak, the fractional efficiency has been predicted as a function of downwind distance, wind speed and windbreak height and porosity. An analytical model and computer algorithm are proposed to enable engineers to predict the fractional efficiency for any source and wind profile of their choosing.

Electrical Charging of Macroscopic Particles Using a Beta Source and Electric and Magnetic Fields

A theoretical and experimental study of an aerosol particle charging apparatus that utilizes a 407-MBq (11-mCi) /sup 90/Sr--/sup 90/Y beta source and electric and magnetic fields has been performed. Fluid models of electron trajectories in the presence of the magnetic field, ion generation due to electron energy deposition, and particle charge acquisition due to ion transport are developed and applied to the experimental apparatus. Calculated average axial ion generation rates on the order of 10/sup 14//m/sup 3/ s are confirmed by experimental measurements, and calculated radial profiles are in good agreement with experiments. Calculated and experimental charging rates agree within 30% for 50- to 100-..mu..m-dia glass spheres in an electric field of 100 kV/m and a magnetic field of 0.141 T. It is found that both the magnitude and spatial distribution of the ion generation rate play important roles in determining the rate of charge acquisition by an aerosol particle in a partially ionized gas subjected to an external electric field.