Patent Description:
Hydrodynamic separators are used in a variety of industries for concentration and/or separation of particles in fluid streams such as hydrocarbon liquids, beverages, aqueous solutions, and the like. Particles suspended in the fluid may cause problems in system processes (such as, for example, in fuel or hydraulic systems), may generally be undesirable to consumers (for example, pulp in orange juice or impurities in beer or wine), or may be subject to different processing steps than the fluid (such as in sewage treatment). It can be desirable to design such hydrodynamic separators to achieve proper particle separation with minimal pressure drop to improve particle separation and efficiency in terms of both energy expenditure and time. <CIT> discloses an example of a hydrodynamic separator for separating diseased cells, which utilizes linear or spiral channels to separate cells based on their reduced deformability or size differences. Further examples of devices for separating particles dispersed in fluids are also disclosed in <CIT> and <CIT>.

A hydrodynamic separator is disclosed in any one of claims <NUM>-<NUM>.

In various embodiments, such a system is configured to have a Dean Number (De) between <NUM> and <NUM>. Additionally or alternatively, the particle diameter (a) is greater than <NUM>% of the hydraulic diameter (DH). Additionally or alternatively, the liquid channel length (LD) is no greater than <NUM>% more than the linear focusing length (Lf). Additionally or alternatively, the liquid channel length (LD) is no greater than <NUM>% more than the linear focusing length (Lf). Additionally or alternatively, the particles are up to three times as dense as the liquid. Additionally or alternatively, the outlet comprises a first outlet and a second outlet. Additionally or alternatively, the liquid channel is one of a plurality of identical liquid channels. Additionally or alternatively, the liquid channel has a first region having a first channel width and a second region having a second channel width, and a tapered region extending from the first channel width to the second channel width.

Some embodiments disclosed herein relate to a hydrodynamic separator configured to separate a liquid having dispersed particles. The hydrodynamic separator has a substrate and a liquid channel defined by the substrate, where the liquid channel has an inlet and an outlet. The liquid channel is configured to receive a liquid having a Reynolds number (Re) within the channel. The liquid channel is curved to define an inner radius (Rc) and has a liquid channel length (LD) along the curve. The liquid channel has a rectangular cross-section along the length of the curve, where the rectangular cross-section has a height, a width (w), and a hydraulic diameter (DH). The liquid channel length (LD) is greater than or equal to a linear focusing length (Lf), where <MAT>.

Some embodiments relate to a hydrodynamic separator configured to separate a liquid having dispersed particles having a diameter (a). The hydrodynamic separator has a substrate and a liquid channel defined by the substrate, where the liquid channel is configured to receive a liquid having a Reynolds number (Re) within the channel. The liquid channel has an inlet and an outlet, and the liquid channel is curved to define an inner radius (Rc) and has a liquid channel length (LD) along the curve. The liquid channel has a rectangular cross-section along the length of the curve. The rectangular cross-section has a height, a width (w), and a hydraulic diameter (DH). The liquid channel length (LD) is greater than or equal to a linear focusing length (Lf), and <MAT>.

Some embodiments relate to a hydrodynamic separator configured to separate a liquid having dispersed particles having a particle diameter (a). The hydrodynamic separator has a substrate and a liquid channel defined by the substrate. The liquid channel is configured to receive a liquid having a Reynolds number (Re) within the channel and the liquid channel has an inlet and an outlet. The liquid channel is curved to define an inner radius (Rc) and has a liquid channel length (LD) along the curve about a central axis. The liquid channel has a rectangular cross-section along the length of the curve, where the rectangular cross-section has a height, a width (w), and a hydraulic diameter (DH). The liquid channel has a focusing angle (α) about the central axis, where <MAT>. The liquid channel extends circumferentially about the central axis to an arc measure greater than or equal to the focusing angle α.

In various embodiments, such a system is configured to have a Dean Number (De) between <NUM> and <NUM>. Additionally or alternatively, the particle diameter (a) is greater than <NUM>% of the hydraulic diameter (DH). Additionally or alternatively, the arc measure is no greater than <NUM>% more than the focusing angle. Additionally or alternatively, the arc measure is greater than <NUM> degrees, and the liquid channel defines a helix. Additionally or alternatively, the arc measure is less than <NUM> degrees. Additionally or alternatively, the particles are up to three times as dense as the liquid. Additionally or alternatively, the outlet comprises a first outlet and a second outlet. Additionally or alternatively, the liquid channel is one of a plurality of identical liquid channels. Additionally or alternatively, the liquid channel has a first region having a first channel width and a second region having a second channel width, and a tapered region extending from the first channel width to the second channel width.

Some embodiments relate to a hydrodynamic separator configured to separate a liquid having dispersed particles having a diameter (a). The separator has a substrate and a liquid channel defined by the substrate. The liquid channel is configured to receive a liquid having a Reynolds number (Re) within the channel. The liquid channel has an inlet and an outlet. The liquid channel has a curved inner wall defining an inner radius (Rc) and a curved outer wall defining an outer radius. The liquid channel has a liquid channel length (LD) along the curved inner wall. The liquid channel has a rectangular cross-section along the liquid channel length. The rectangular cross-section has a channel width (w) between the inner wall and outer wall, where the channel has a tapered region where the channel width tapers between the inlet and the outlet.

In some such embodiments, the channel width increases towards the outlet. Additionally or alternatively, the channel width increases at a constant rate between the inlet and the outlet. Additionally or alternatively, the channel width decreases towards the outlet. Additionally or alternatively, the inner radius is constant from the inlet to the outlet. Additionally or alternatively, the outer radius tapers outward between the inlet and the outlet.

The present technology may be more completely understood and appreciated in consideration of the following detailed description of various embodiments in connection with the accompanying drawings.

The figures are rendered primarily for clarity and, as a result, are not necessarily drawn to scale. Moreover, various structure/components, including but not limited to fasteners, electrical components (wiring, cables, etc.), and the like, may be shown diagrammatically or removed from some or all of the views to better illustrate aspects of the depicted embodiments, or where inclusion of such structure/components is not necessary to an understanding of the various exemplary embodiments described herein. The lack of illustration/description of such structure/components in a particular figure is, however, not to be interpreted as limiting the scope of the various embodiments in any way.

Hydrodynamic separators are microfluidic devices capable of focusing particles within a fluid stream relying only on the forces due to internal fluid flow. The particles can be separated from a portion of the fluid steam and/or separated from particles of other sizes within the fluid stream. The hydrodynamic separator generally defines a fluid channel having an inlet and an outlet having at least two flow branches. Particles within a particular size range may be focused, or concentrated, into one of the two flow branches. For example, particles exceeding a threshold size range are focused into one of the two flow branches. The concentrated portion of the fluid flow may be removed from the system or retained for further processing. Any remaining particles may flow through the at least two flow branches.

<FIG> is a schematic representation of an example system <NUM> consistent with some implementations of the technology disclosed herein. The system <NUM> is a hydrodynamic separator system that is configured to focus particles that are suspended in a fluid stream. The system <NUM> has a hydrodynamic separator <NUM> having an inlet <NUM> and an outlet <NUM>. A fluid pump <NUM> creates fluid communication between a fluid source <NUM> and the hydrodynamic separator <NUM>. In particular, the fluid pump <NUM> is configured to pump fluid from the fluid source <NUM> through an inlet flow channel <NUM> to the inlet <NUM> of the hydrodynamic separator <NUM>. The fluid is configured to flow through a liquid channel <NUM> of the hydrodynamic separator <NUM> to the outlet <NUM>. A first outlet branch <NUM> and a second outlet branch <NUM> can lead from the outlet <NUM> to other systems or other system components. In some embodiments, fluid flowing through the first outlet branch <NUM> is configured to have a higher concentration of particles within a particular size range compared to fluid flowing through the second outlet branch <NUM>.

The hydrodynamic separator consistent with the technology disclosed herein are generally constructed of a substrate <NUM>. The substrate <NUM> defines the liquid channel <NUM> therein. The substrate can be constructed of a variety of different materials and combinations of materials. The substrate can be polymeric, in some embodiments. In some examples the substrate is polydimethylsiloxane (PDMS). In some embodiments the substrate can include glass. In some embodiments the substrate can include a non-reactive metal. In some embodiments the substrate can include one or more adhesive layers, such as a pressure-sensitive adhesive. In some embodiments the substrate may be two or more materials, such that the walls of the channels may be two or more materials.

The liquid channel <NUM> is generally configured to accommodate liquid flow. The liquid channel <NUM> defines the inlet <NUM> and the outlet <NUM>. The liquid channel <NUM> defines a channel length LD from the inlet <NUM> to the outlet <NUM>. The liquid channel <NUM> is generally curved to define an inner radius RC about a central axis x. As such, the liquid channel <NUM> extends circumferentially about the central axis x to define a channel arc measure. In the current example, the liquid channel <NUM> extends about <NUM>° about the central axis x. In the current example, the inner radius RC is substantially constant along the length of the channel, but in some other examples, the inner radius RC can vary.

The liquid channel <NUM> generally has a rectangular cross-section along the channel length, which is visible in <FIG>. The cross-section of the liquid channel <NUM> is generally perpendicular to the direction of fluid flow through the channel <NUM>. The channel <NUM> has a height (h) that is visible in <FIG>, and a width (w) that is visible in both <FIG>. The channel <NUM> also has a hydraulic diameter (DH). The following equation is used to calculate the hydraulic diameter of a microfluidic channel having a rectangular cross-section: <MAT>.

The liquid channel <NUM> can be formed in the substrate <NUM> through molding operations, photolithography, and 3D printing, as examples. In some examples, the liquid channel <NUM> is formed in the substrate <NUM> through injection molding or embossing of plastics. Other approaches can also be used to form the liquid channel <NUM>. In various embodiments, the hydrodynamic separator <NUM> defines a plurality of liquid channels <NUM> that are configured to operate in parallel. In various embodiments, the hydrodynamic separator <NUM> has at least <NUM> liquid channels. In various embodiments, the hydrodynamic separator <NUM> has at least <NUM> liquid channels or at least <NUM> liquid channels.

In some embodiments where the hydrodynamic separator <NUM> has a plurality of liquid channels, one liquid channel <NUM> can be defined within a single a substrate layer. In some such embodiments, multiple substrate layers can be layered in a stacked configuration such that each of the plurality of liquid channels <NUM> defined by each substrate layer are also in a stacked configuration. The stacked layers of substrate and the liquid channels <NUM> to form the hydrodynamic separator <NUM>. The hydrodynamic separator <NUM> can define the inlet flow channel <NUM> upstream of and in direct fluid communication with each of the microfluidic channel inlets (such as inlet <NUM>). The inlet flow channel <NUM> will generally have a hydraulic diameter that is larger than the hydraulic diameter of each of the liquid channels <NUM>. The hydrodynamic separator <NUM> can define the first outlet branch <NUM> and the second outlet branch <NUM> that are both positioned downstream of, and in direct fluid communication with, each the outlet <NUM>. Each of the first outlet branch <NUM> and the second outlet branch <NUM> will generally have a diameter that is larger than the hydraulic diameter of each of the liquid channels. Such a configuration may advantageously equalize flow through the channels.

The liquid channel <NUM> is configured to receive a liquid having a Reynolds number (Re) within the liquid channel. The fluid flow within a curving channel is described by two non-dimensional numbers, the Reynolds number and the Dean Number. The Reynolds number describes the ratio of inertial forces to viscous forces, and is defined as: <MAT> where ρ is the fluid density, U is the average fluid velocity, and µ is the dynamic viscosity of the fluid. In hydrodynamic separators the Reynolds number is typically small (<<NUM>), which means that the flow profile is laminar. In various embodiments, the system is configured to have a Dean Number (De) between <NUM> and <NUM>. In various embodiments, the system is configured to have a Dean Number between <NUM> and <NUM>. The Dean number describes fluid behavior in a curved pipe and accounts for inertial forces, centripetal forces, and viscous forces acting on the fluid. The Dean number is defined as: <MAT>.

The hydrodynamic system <NUM> is generally configured to focus particles in the liquid channel <NUM>. As used herein, the term "particle" refers to a discrete amount of material, which is dispersed in a fluid. Non-limiting examples of material that may be formed particles include dirt, metal, cells, air bubbles, fat, water droplets. In one particular example, water droplets may be dispersed in a hydrocarbon fluid, such as gasoline or diesel fuel, to form an emulsion. In another example, air bubbles may be dispersed in a hydraulic fluid. In another example, cells may be dispersed in an aqueous fluid. In yet other examples, particles may be pulp in orange juice, fat in milk, and impurities in beer or wine.

In various implementations, hydrodynamic separator <NUM> is configured to focus particles having a diameter of greater than <NUM>% of the hydraulic diameter of the liquid channel <NUM>. Particles whose diameter are greater than <NUM>% of the channel hydraulic diameter are generally focused towards the inner wall when the Dean number ranges from <NUM> to <NUM>. The hydrodynamic separator is generally configured to focus particles having a diameter that is less than or equal to <NUM>% of the channel height. In various examples, for purposes of calculations provided herein, the particles have a sphericity of greater than <NUM>. For non-spherical particles, for purposes of calculations provided herein, the particle diameter is considered to be the equivalent spherical diameter. In various embodiments, hydrodynamic separators consistent with the technology disclosed herein are configured to focus particles having a density up to three times as dense as the liquid in the liquid channel <NUM>.

Particle focusing occurs in two distinct stages. The first stage is a particle migration stage where the suspended particles migrate from across the liquid channel <NUM> to the edges of the liquid channel <NUM>. The particle migration stage generally starts at the liquid channel inlet <NUM> and extends a particle migration length Lo of the liquid channel <NUM> to define the particle migration region <NUM> of the liquid channel <NUM>. In this region no additional focusing on the inside wall <NUM> of the liquid channel <NUM> is observed. The second region is a linear focusing region <NUM> in which the amount of focusing on the inside wall <NUM> increases linearly along the channel length. The focusing continues until a maximum particle focusing is reached. No additional focusing is observed after maximum particle focusing is reached. Linear focusing region <NUM> has a linear focusing length Lf that is the length necessary to achieve maximum particle focusing. The linear focusing region <NUM> generally extends from the particle migration region <NUM> towards the channel outlet <NUM>.

The length of the liquid channel <NUM> after the linear focusing region <NUM> is referred to as the fully focused region <NUM>. The fully focused region <NUM> has a length that extends from the linear focusing region <NUM> to the outlet <NUM>. In various implementations it can be desirable to limit or eliminate the fully focused region <NUM> in order to decrease the energy requirements of the system by lowering the pressure drop across the liquid channel <NUM> while still achieving maximum particle focusing.

<FIG> is a graph depicting representative focusing behavior demonstrating the three stages of particle focusing along the length of a curved liquid channel. The particle migration region <NUM> accounts for approximately the first <NUM> of the length of the channel, and the linear focusing region <NUM> follows. In this example, the linear focusing region <NUM> achieves maximum particle focusing around <NUM> along the length of the liquid channel. Once the maximum value of particle focusing is reached, the particle focusing may stay approximately constant. This region of the device is considered the fully focused region <NUM>. In this example, the maximum focusing percentage in the fully focused region shows is about <NUM>% (that is, <NUM>% of the particles are focused).

Mathematically, the length of the linear focusing region necessary to achieve maximum particle focusing in a curved channel (such as that depicted in <FIG>) is a linear function based on the radial component of the particle velocity through the channel. According to existing literature (see, for example, <NPL>. ), the magnitude of the radial component of the Dean Flow profile, or the linear focusing rate UD, is the following: <MAT>.

This relationship was tested on rectangular channels using computational fluid dynamics in STAR-CCM+ software by Siemens PLM Software based in Plano, Texas. To measure the radial flow component, a function probe was inserted in the center of the virtual fluid domain, aligned with the depth of the channel (in the Z direction) at discrete radial positions along the primary fluid flow direction. An example series of typical radial flow profiles are shown in <FIG>, where the radial velocity is a function of the depth through the center of the channel. The flow profiles shown are of a single device geometry and fluid combination across varying Dean numbers but with constant channel height h (<NUM>), width w (<NUM>), and inner radius Rc (<NUM>). In this coordinate system positive flow velocities indicate fluid is moving towards the outside wall of the device, while negative flow velocities indicate fluid is moving towards the inside wall of the device. At the center of the channel depth the maximum radial flow component is observed. This corresponds to the maximum velocity towards the outer wall due to fluid inertia. There are two minimum radial flow components, symmetrically observed above and below the center of the channel depth. These flow components are the recirculating flow towards the inside wall, which are ultimately responsible for passively moving particles to the final focusing position.

The minimum radial flow velocities for different liquid channel widths at four different Dean Numbers (De = <NUM>, <NUM>, <NUM>, <NUM>) were plotted against the literature equation for the magnitude of the radial component of the Dean Flow profile, which is reflected in <FIG>. As is visible, the equation does not define a linear relationship across different liquid channel widths and thus is not an accurate predictor of radial velocity. Over the course of further testing and analysis, the following relationship was discovered for the linear focusing rate UD: <MAT>.

This equation was plotted against the minimum radial velocity and the results are reflected in <FIG>. As is visible, the data from devices with different liquid channel widths collapse into a single linear curve. This relationship holds true when changing device geometry (width, height, and Rc) and fluid properties (viscosity and density) over the range of Dean numbers relevant to hydrodynamic separators (<NUM> < De < <NUM>). Specifically, the minimum radial velocity was found to be the following: <MAT> where µ is in cP, w is in microns, ρ is g/cm<NUM> and UD is in m/s.

Based on the minimum radial velocity, an equation to determine the length of the linear focusing region to obtain maximum particle focusing can be derived. The velocity across the width of the liquid channel is nearly constant, so the time it takes for a particle to transit the width of the liquid channel to the inner wall is: <MAT>.

As such, the length of the linear focusing region is: <MAT> where U is the average downstream velocity of the fluid. Substituting in <MAT> yields: <MAT> and, more specifically, <MAT>.

Linear focusing region is generally shorter at a higher Dean number, and because the operative range for a hydrodynamic separator consistent with the technology disclosed herein is a Dean number ranging from <NUM> to <NUM>, the linear focusing length Lf will generally be a minimum of <MAT>.

Using the particle focusing rate (i.e. the slope of the linear focusing region) the length required to focus an additional <NUM>% of particles was calculated. An additional <NUM>% of particles being focused would bring the focusing efficiency to greater than <NUM>% because at the device inlet <NUM>-<NUM>% of the particles are already in the focusing position. The observed focusing length associated with experimental results were plotted against the focusing length Lf equation above, which is reflected in <FIG>. Error bars correspond to the standard error based on the uncertainty in the slope of the linear focusing region. This fit shows a clear trend, which is dominated by changes in device width and radius of curvature. A closer look at the data suggests that the focusing length Lf is dependent on particle size. Specifically, smaller particles focus faster than larger particles. Indeed, particles of different sizes will experience different lift forces, and thus transit the width of the device at different heights. It was discovered that taking the linear focusing length Lf and multiplying it by the particle confinement (a/Dh) yields <MAT> and, more specifically, <MAT> which is plotted against the observed experimental focusing lengths as reflected in <FIG>. The data collapsed onto a linear fit, giving an R<NUM> value of greater than <NUM>.

Instead of being described in terms of the length of the linear focusing region Lf, the linear focusing region can also be described in terms of the focusing angle (α), which is the arc measure of the linear focusing region <NUM> about the central axis x: <MAT> or, more specifically, <MAT> which is plotted against experimental data in <FIG>. As demonstrated, various liquid channels consistent with the technology disclosed herein require a focusing angle of greater than <NUM> degrees, indicating that full focusing cannot occur with a "simple" hydrodynamic separator, where a "simple" hydrodynamic separator is one where the liquid channel is less than a full revolution about the central axis x. Liquid channels that fully focus particles within one revolution about the central axis x generally have a small width, high Reynolds number, and large hydraulic diameter.

A series of experiments were conducted that measured the actual particle migration length L<NUM> and the particle focusing length Lf of various hydrodynamic systems consistent with the technology disclosed herein. Hydrodynamic separators of varying device heights and widths were created out of PDMS and glass slides using standard methods. Solutions of fluorescently labeled particles were introduced to the hydrodynamic separator channel at known flowrates within the Dean Numbers of <NUM> - <NUM>. Images were taken at various location along the hydrodynamic separator using a CMOS camera. Image processing was used to identify particle concentration as a function of channel position and length. The particle focusing length Lf was also calculated in accordance with equations provided above. The results are reflected in Table <NUM>, below.

Across the experimental results, the particle focusing length Lf was greater than the particle migration length L<NUM>. The particle migration length L<NUM> ranged from <NUM>% of the total liquid channel length LD to <NUM>% of the total liquid channel length LD. Furthermore, the particle migration length L<NUM> ranged from <NUM>% of the particle migration length Lf to <NUM>% of the particle migration length Lf. As such, in some embodiments, liquid channels consistent with the technology disclosed herein will have a liquid channel length LD that is about equal to the particle migration length Lf. In various embodiments, liquid channels consistent with the technology disclosed herein will have a liquid channel length LD that is greater than the particle migration length Lf. Based on the collected data, it appears that, in many embodiments, the liquid channel length LD is less than <NUM>% greater than the particle migration length Lf. The liquid channel length LD may be less than or equal to <NUM>% greater than the particle migration length Lf. The liquid channel length LD may be less than or equal to <NUM>% greater than the particle migration length Lf. In some embodiments the liquid channel length LD may be from <NUM>% to <NUM>% greater than the particle migration length Lf.

<FIG> and <FIG> show a schematic view of another example hydrodynamic separator <NUM> consistent with some embodiments. <FIG> is a schematic perspective view and <FIG> is a schematic facing view of the inlet side of the hydrodynamic separator, where the liquid channel <NUM> is represented by dotted lines. The hydrodynamic separator <NUM> is generally consistent with the descriptions above except where contradictory. The hydrodynamic separator <NUM> is configured to focus particles that are dispersed in a liquid stream. The hydrodynamic separator <NUM> is constructed of a substrate <NUM>. The substrate <NUM> defines a liquid channel <NUM> having an inlet <NUM> and an outlet <NUM>. The liquid is configured to flow through the liquid channel <NUM> of the hydrodynamic separator <NUM> from the inlet <NUM> to the outlet <NUM>.

The liquid channel <NUM> defines a channel length LD from the inlet <NUM> to the outlet <NUM>. The liquid channel <NUM> is generally curved to define an inner radius RC about a central axis x. As such, the liquid channel <NUM> extends circumferentially about the central axis x to define a channel arc measure. In the current example, the liquid channel <NUM> extends about <NUM>° about the central axis x. In the current example, the inner radius RC is substantially constant along the length of the channel. In the current example, the liquid channel <NUM> forms a helix about the central axis x. The helical arrangement of the liquid channel <NUM> accommodates both a constant inner radius RC and multiple revolutions about the central axis x. In some embodiments, however, the inner radius is not constant.

The liquid channel <NUM> generally has a rectangular cross-section along the channel length, which is visible in <FIG> at the inlet <NUM>. The cross-section of the liquid channel <NUM> is generally perpendicular to the direction of fluid flow through the channel <NUM>. The channel <NUM> has a height (h) that is visible in <FIG>, and a width (w) that is visible in <FIG>. The channel <NUM> also has a hydraulic diameter (DH) as has been disclosed.

Similar to examples discussed above, particle focusing can occur in two distinct stages. To optimize the liquid channel length LD, and a fully focused region is avoided so that the entire length of the liquid channel is the particle migration length L<NUM> and the particle focusing length Lf. Optimization of the liquid channel length LD and/or arc measure is generally consistent with the discussion above.

In various embodiments, such as embodiments consistent with the example of <FIG> and <FIG>, the liquid channel dimensions such as height h, width w, and inner radius RC are substantially constant along the length of the liquid channel, meaning that such dimensions do not vary beyond <NUM>% of the weighted average value of the dimension along the length of the liquid channel. The equations provided herein are generally for optimization of a liquid channel length where the liquid channel has a substantially constant inner radius RC. In some embodiments, the channel width w is not substantially constant along the length of the channel. In such embodiments, the weighted average of the channel width w along the channel length can be used in the equations provided herein for optimization of the liquid channel length. In various examples, the optimized channel length may be based on the weighted average of the channel dimensions within the focusing region.

<FIG> is a schematic representation of yet another example hydrodynamic separator system consistent with some embodiments. The system has a fluid source <NUM>, a pump, an inlet flow channel <NUM> and outlet flow branches <NUM>, <NUM> as discussed above with reference to <FIG>. The system has a hydrodynamic separator <NUM> is generally consistent with the descriptions above except where contradictory. The hydrodynamic separator <NUM> is configured to focus particles that are dispersed in a liquid stream. The hydrodynamic separator <NUM> is constructed of a substrate <NUM>. The substrate <NUM> defines a liquid channel <NUM> having an inlet <NUM> and an outlet <NUM>. The liquid is configured to flow through the liquid channel <NUM> of the hydrodynamic separator <NUM> from the inlet <NUM> to the outlet <NUM>.

The liquid channel <NUM> defines a channel length LD from the inlet <NUM> to the outlet <NUM>. The liquid channel <NUM> is generally curved to define an inner radius RC about a central axis x. As such, the liquid channel <NUM> extends circumferentially about the central axis x to define a channel arc measure. In the current example, the liquid channel <NUM> extend s about <NUM>° about the central axis x. In the current example, the inner radius RC is substantially constant along the length of the channel, but in some other embodiments the inner radius is not constant.

The liquid channel <NUM> generally has a rectangular cross-section along the channel length, which is not currently visible. The liquid channel <NUM> has a height (h) that is not currently visible, and a first channel width w<NUM> and a second channel width w<NUM> that is visible in <FIG>. In this particular example, the liquid channel <NUM> does not have a constant width. The channel width tapers between the inlet and the outlet. Specifically, a first region <NUM> of the liquid channel <NUM> defines a first width w<NUM>, a second region <NUM> of the liquid channel <NUM> defines a second width w<NUM>, and a tapered region <NUM> extends between the first width w<NUM> and the second width w<NUM> to provide a smooth transition from the first width w<NUM> to the second width w<NUM>. The word "taper" is used herein to mean a relatively gradual expansion/contraction that excludes an abrupt transition, such as a stepped transition, between the first width w<NUM> and the second width w<NUM>. The taper can be linear, parabolic, or exponential, as examples. Other taper shapes are additionally possible, including combinations of tapered shapes along the length of the tapered region.

In some embodiments the first region <NUM> and the second region <NUM> can have about equal lengths, but in the current embodiment the first region <NUM> is shorter than the second region <NUM>. In some embodiments the first region <NUM> has a larger length than the second region <NUM>. In some embodiments the tapered region <NUM> is longer than one or both of the first region <NUM> or second region <NUM>. In the current example, only the radius of the outer wall <NUM> of the liquid channel <NUM> tapers between first region <NUM> and the second region <NUM>. In some other embodiments, the radius of the outer wall <NUM> and the radius of the inner wall <NUM> taper between the first region <NUM> and the second region <NUM>. In yet other embodiments, only the radius of the inner wall <NUM> tapers between the first region <NUM> and the second region <NUM>.

Embodiments of liquid channels where the width tapers from a smaller width to a larger width may be desirable in some implementations. The smaller the width of a liquid channel <NUM>, the shorter the pathway for particles to focus towards the inner wall <NUM>. The larger the width of a liquid channel <NUM>, the lower the pressure drop along the channel <NUM>, which reduces the energy needed to pump liquid through the channel <NUM>. As such, it may be desirable in some implementations to have a liquid channel width that increases along at least a portion of the length of the liquid channel <NUM>.

In some implementations, the optimal channel length can be approximated by using the weighted average of the width along the length of the liquid channel <NUM> in such calculations. In some implementations consistent with <FIG>, to achieve maximum focusing, the following is true: <MAT> where Lw1 and Lw2 are the actual lengths of the first region <NUM> (having the first width w<NUM>) and the second region <NUM> (having the second width w<NUM>) of the channel, respectively. Lf(w1) and Lf(w2) are the theoretical linear focusing lengths of a channel consistent with the first region <NUM> and a channel consistent with the second region <NUM>, respectively. In the case that the length of the tapering region <NUM> is relatively small relative to Lw1 and Lw2 the linear focusing length (Lf) would be the following: <MAT>.

Where <MAT> and corresponds to the percent of focusing that occurs within the first region <NUM> and where <MAT> and corresponds to the percent of additional focusing that occurs within the second region <NUM>. By "relatively small" it is meant that the tapering region <NUM> is less than <NUM>%, <NUM>%, or even less than <NUM>% of the combined length of the first region <NUM> and the second region <NUM>.

In some other implementations, for purposes of calculating the total length of the focusing region, a first portion of the tapered region may be considered part of the length of the first region <NUM> and a second portion of the tapered region may be considered part of the length of the second region <NUM>. For example, half of the length of tapered <NUM> region may be considered part of the length of the first region <NUM> and the other half of the length of the tapered region <NUM> may be considered part of the length of the second region <NUM>. Other approaches may also be used.

A hydrodynamic separator is designed to focus <NUM> particles in water. Key parameters are in Table <NUM>. The flowrate range at which particles focus is approximately <NUM>/min to <NUM>/min (Dean Number = <NUM> to <NUM>). The linear focusing region length is calculated for these flowrates as shown in Table <NUM>. The system pressure drop is an estimated pressure drop based on straight channel calculations and does not include minor losses or effects of secondary flows.

A hydrodynamic separator is designed to focus <NUM> particles in a fluid. Key parameters are in Table <NUM>. The linear focusing region length and estimated pressure drop can be calculated for different hydrodynamic separator radii at a constant Dean Number (De = <NUM>). This data is shown in Table <NUM>. The system pressure drop is an estimated pressure drop based on straight channel calculations and does not include minor losses or effects of secondary flows. At larger radii of curvatures the flowrate through the channel increases, but at the drawback of increased pressure drop.

A hydrodynamic separator is designed to focus <NUM> - <NUM> particles in wine. This represents the process of removing yeast from beer or wine during clarification. Key parameters are in Table <NUM>. The linear focusing region length is calculated for different flowrates as shown in Table <NUM>. The largest particle size (<NUM>) is used for this calculation. The system pressure drop is an estimated pressure drop based on straight channel calculations and does not include minor losses or effects of secondary flows.

A hydrodynamic separator is configured to focus <NUM> - <NUM> particles in wine. In some implementations, such a separator can be used to remove yeast from beer or wine during clarification. The hydrodynamic separator has two regions of different widths, w<NUM> and w<NUM> and a relatively small transition region having a length of <NUM> or less. The flow rate is <NUM>/min. Key parameters are in Table <NUM>. The separator is configured to accomplish α% of the focusing in the first region, and (<NUM> - α)% of the focusing in the second region, such that particles are fully focused at the end of the second region. The length of each region, Lw1 and Lw2, and the total focusing length, Lf are calculated in Table <NUM>.

While it can generally be observed that by increasing the percentage of focusing in the narrower channel (region <NUM>) that the overall focusing length can be decreased, this will come at the expense of increased pressure drop due to the smaller channel dimensions. An optimal design will depend on application requirements.

It should also be noted that, as used in this specification and the appended claims, the phrase "configured" describes a system, apparatus, or other structure that is constructed to perform a particular task or adopt a particular configuration. The word "configured" can be used interchangeably with similar words such as "arranged", "constructed", "manufactured", and the like.

All publications and patent applications in this specification are indicative of the level of ordinary skill in the art to which this technology pertains.

Claim 1:
A hydrodynamic separator configured to separate a liquid having dispersed particles having a diameter (a), comprising:
a substrate (<NUM>; <NUM>; <NUM>);
a liquid channel (<NUM>; <NUM>; <NUM>) defined by the substrate (<NUM>; <NUM>; <NUM>), the liquid channel (<NUM>; <NUM>; <NUM>) being configured to receive a liquid having a Reynolds number (Re) within the channel, the liquid channel (<NUM>; <NUM>; <NUM>) having an inlet (<NUM>; <NUM>; <NUM>) and an outlet (<NUM>; <NUM>; <NUM>), wherein:
the liquid channel (<NUM>; <NUM>; <NUM>) is generally curved, has a curved inner wall (<NUM>) defining an inner radius (RC) and a curved outer wall (<NUM>) defining an outer radius, wherein the inner radius (RC) is constant from the inlet (<NUM>; <NUM>; <NUM>) to the outlet (<NUM>; <NUM>; <NUM>),
the liquid channel (<NUM>; <NUM>; <NUM>) has a liquid channel length (LD) along the curved inner wall (<NUM>),
the liquid channel (<NUM>; <NUM>; <NUM>) has a rectangular cross-section along the liquid channel length, and
the rectangular cross-section has a channel width (w) between the inner wall (<NUM>) and the outer wall (<NUM>), where the channel (<NUM>; <NUM>; <NUM>) has a tapered region (<NUM>) where the channel width (w) tapers between the inlet (<NUM>; <NUM>; <NUM>) and the outlet (<NUM>; <NUM>; <NUM>), further wherein the channel width (w) increases towards the outlet (<NUM>; <NUM>; <NUM>).