Fluid handling – Processes – Involving pressure control
Reexamination Certificate
2001-10-19
2004-01-20
Chambers, A. Michael (Department: 3753)
Fluid handling
Processes
Involving pressure control
C137S56100R, C429S006000
Reexamination Certificate
active
06679280
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to fluid flow in a manifold, and more particularly, to the conversion of single channel multiphase fluid flow into multi-channel multiphase flows having uniform flow properties.
RELATED ART
Fluid manifolds have a variety of useful industrial applications, some of the more common being fuel supply and exhaust systems for internal combustion engines. These are typical examples of systems using manifolds to channel single phase fluids, such as liquid fuel or gaseous exhaust. Manifolds are also used for communicating multiphase fluids, which consist of two or more components having different phases, e.g. a mixture of liquid and solid particles. One application for multiphase manifolds is in metal-based fuel cells, where fuel in the form of metal particles is entrained in a flow of electrolyte solution, and delivered via a channel to a cell or combination of cells from which electricity is derived by means of oxidation reduction.
A manifold for dividing a single fluid flow into two flow paths can be defined in simplistic form by a single tubular pipe connected to a T coupling. Provided that there are no variations in pipe diameter or other obstructions, fluid flow directed through the tubular pipe splits into two essentially equal parts at the T intersection. The point of abrupt obstruction where the fluid impacts the wall of the T coupling creates a stagnation point where the fluid velocity is zero. The geometry of the T coupling directs the fluid flow radially outward from stagnation point at right angles from the direction of incident flow.
By using a combination of T couplings, a single input flow can be split in successive stages to create any number of multiple output flows. However, one skilled in the art will readily recognize the geometric complexity that this technique introduces into the system after the second stage. Such complexity is not practical for use in a metal/air fuel cell, which requires a more compact arrangement of parallel flow paths in order to integrate the manifold within a portable stacked cell design. More conventional fluid manifolds, such as those used in fuel supply systems of internal combustion engines, are designed for communication of single phase fluids. The geometries of these manifolds are typically customized to interface with their particular engine systems, and as a result, may include branch lines that assume various asymmetrical or complex shapes. Multiphase fluid flow through such a manifold will typically produce undesirable variations in the fluid concentration and/or flow rate of the dispersed phase of the multiphase fluid. Due to differences in the length, there can be differences in the pressure drops at the individual branches. The differences in pressure drops can cause differences in flow rates (e.g., velocities), and thus can result in differences in the flow rates of the dispersed phase. Further, these differences in flow rates can result in different drag forces, and thus can result in different concentrations of the dispersed phase.
Thus, there is presently a need for an improved manifold that can provide uniform flow properties for multiphase fluid flow through a plurality of parallel outlet channels. Moreover, the manifold should be sufficiently compact in design to facilitate integration within a stacked fuel cell.
SUMMARY
In one aspect, the present invention is directed to a novel method for converting a single channel fluid flow into multiple channels of fluid flow having substantially uniform flow properties. The invention is particularly directed for use in multiphase fluid systems that require preservation of dispersed phase concentration and or flow rate.
In one aspect, the invention pertains to methods of converting a single flow of a multiphase fluid into a plurality of separate channeled flows each having substantially the same pressure at the inlet of its channel. Typically, such methods comprise impacting the single flow against a surface to form a stagnation point and a plurality of intermediate flows radiating outward from the stagnation point, and directing at least a portion of this plurality of intermediate flows across a predetermined distance from the stagnation point to form the first plurality of separate channeled flows. Generally, this predetermined distance is selected from a range of distances that produce substantially identical pressures at each of the channel inlets.
In another aspect, the invention pertains to methods of forming a plurality of separate flows of a multiphase fluid each having substantially the same flow rate. Typically, such methods comprise impacting a single flow of the multiphase fluid against a surface so as to form a stagnation point and the plurality of separate flows radiating outward from the stagnation point. Consistent with this impact, the separate flows generally each have substantially the same flow rate.
In a further aspect, the invention pertains to methods of forming a plurality of separate channeled flows of a multiphase fluid from a plurality of intermediate flows, each separate channeled flow having substantially the same pressure at the inlet of its channel. Typically, such methods comprise directing at least a portion of the plurality of intermediate flows across a predetermined distance from a stagnation point to a plurality of channels to form the first plurality of separate channeled flows. Generally, this predetermined distance is selected from the range of distances that produce substantially identical pressures at each of the channel inlets.
In an additional aspect, the invention pertains to apparatus comprising a means for converting a single flow of a multiphase fluid into a plurality of separate channeled flows of the multiphase fluid. Typically, such apparatus comprise means for converting the single flow into the plurality of separate channeled flows such that one or more of the following conditions are met: (i) each of the separate channeled flows has substantially the same pressure at the inlet of its channel, (ii) each of the separate channeled flows is formed from at least a portion of a plurality of intermediate flows directed in a direction substantially perpendicular to the direction of the single flow, and (iii) each of the separate channeled flows is formed from at least a portion of the plurality of intermediate flows formed by impacting the single flow onto a surface of the apparatus to form a stagnation point.
All of the aspects presented above may be suitable for many applications, including without limitation incorporation in a manifold for operation in a fuel cell subsystem and/or a fuel cell and/or an internal combustion engine.
In another aspect, the invention pertains to novel manifolds. In one embodiment, such manifolds comprise an enclosure comprising a surface, a multiphase fluid inlet, and a plurality of multiphase fluid outlets. Generally, the surface of the manifold is characterized in that it is capable of impacting a single flow of the multiphase fluid directed from the multiphase fluid inlet to the surface in a flow direction substantially perpendicular to the surface, wherein said impacting forms a stagnation point from which radiate outward a plurality of flows of multiphase fluid, and directing at least a portion of the resulting plurality of flows to the plurality of multiphase fluid outlets. Usually, the manifold is further characterized in that the average distance between the stagnation point and the plurality of multiphase fluid outlets is a predetermined distance selected from the range of distances that provide that each of the plurality of flows has substantially the same pressure at the beginning of its associated multiphase fluid outlet.
In another embodiment, such manifolds comprise apparatus comprising a means for converting a single flow of a multiphase fluid into a plurality of separate channeled flows of the multiphase fluid, in accordance with the invention.
In a further aspect, the invention pertains to novel fuel cell subsystems. Typically, the
Chambers A. Michael
Howrey Simon Arnold & White , LLP
Metallic Power, Inc.
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