Hajrudin Pasic

Use of membrane collectors in electrostatic precipitators.

ABSTRACT Membrane collection surfaces, developed and patented by researchers at Ohio University, were used to replace steel plates in a dry electrostatic precipitator (ESP). Such replacement facilitates tension-based rapping, which shears the adhered particle layer from the collector surface more effectively than hammer-based rapping. Tests were performed to measure the collection efficiency of the membranes and to quantify the potential improvements of this novel cleaning technique with respect to re-entrainment. Results indicate that even semiconductor materials (e.g., carbon fibers) collect ash nearly as efficiently as steel plates, potentially indicating that collection surface resistivity is primarily dictated by the accumulated ash layer and not by the underlying plate conductivity. In addition, virtually all sheared particles separated from the collecting membranes fell within the boundary layer of the membrane, indicating extremely low potential for re-entrainment.

MWESP: Membrane tubular wet electrostatic precipitators

After extensively testing MWESP units, researchers have found that they have many important advantages over conventional plate-based or tubular wet electrostatic precipitators (WESP); they are more efficient, light weight, easy to maintain, and are of significantly lower cost.

Membrane based electrostatic precipitation

Legislation from the US EPA aimed at governing the release of particles smaller than 2.5 mm into the atmosphere will have a major impact on coal-fired power plants across the USA. Researchers lead by Professor Hajrudin Pasic at Ohio University have come up with a unique design for wet and dry electrostatic precipitators (ESP) that relies on membrane technology to efficiently capture small particles. In this article, some recent results related to particle collection and removal efficiencies, selection of membrane materials and other relevant issues, as well as comparisons with existing ESP technologies are presented.

Experimental study of cross-flow wet electrostatic precipitator

ABSTRACT This paper reports development and testing of a novel cross-flow wet electrostatic precipitator (WESP), recently patented at Ohio University, that utilizes vertical columns of permeable material in the form of polypropylene ropes placed in a cross-flow configuration within a flue gas stream. The cross-flow design has large surface area, which provides scrubbing action; therefore, it has the potential for removing multiple pollutants, including particulates, gases, vapors, and mists. In this new method, the ropes are kept wet by the liquid (water) introduced from the top of the cells running downward on the ropes by capillary action, making the permeable materials act as the ground electrode for capturing particles from the flue gas. Preliminary testing has shown an efficiency of well above 80% using two cells and three sets of discharge electrodes. Since the material of construction is primarily corrosion-resistant polymeric material, both weight and cost reductions are expected from this new design. Implications: The newly invented cross-flow WESP exhibit particulate collection efficiency of well above 80% when introduced in particulate-laden exhaust flow. This value was obtained using a two cells and three discharge electrodes configuration. The electric field strength has a substantial effect on the collection efficiency. Also, the pressure drop test results indicate that there is a potential to increase the collection area, which, in turn, will increase the collection efficiency further.

Dynamics of a Cantilever Electrode Beam on a Vibrating Base

Vibration of a simple uniform Bernoulli-Euler cantilever beam attached to a rigid base vibrating in a direction perpendicular to the beam is studied both analytically and experimentally. The objective is to study electrode deflection in electrostatic precipitators, with emphasis on the interaction of the vibrating electrode with the ambient fluid. The analytical solution can be used to find reliable estimates of the maximum vibration amplitude of the electrodes, which is a primary cause of detrimental sparking of the electrodes. An experimental system was built to validate the analytical results and to investigate the importance of the beam interaction with the ambient air/fluid medium — which is often overlooked in most of the existing analytical models. The results demonstrate that the drag effect of the ambient air can change the characteristics of the vibration significantly, thereby limiting the applicability of the analytical or numerical results.Copyright

A numerical algorithm for solving manipulator forward dynamics

Abstract A new algorithm is presented for iterative solution of systems of nonlinear ordinary differential equations (ODEs) with any order for multibody dynamics and control problems. The collocation technique (based on the explicit fixed-point iteration scheme) may be used for solving both initial value problems (IVPs) and boundary value problems (BVPs). The BVP is solved by first transforming it into the IVP. If the Lipschitz constant is large and the algorithm diverges in a single (‘long’) domain, the domain is partitioned into a number of subdomains and the local solutions of the corresponding BVPs are matched either locally (in parallel) or globally. The technique is general and may be applied to general systems of ODEs in any field. As an illustration, the forward dynamics problem of a manipulator is solved as an IVP and then as a BVP.