WO2025099686A1

WO2025099686A1 - Recirculation delivery unit for fuel cell

Info

Publication number: WO2025099686A1
Application number: PCT/IB2024/061132
Authority: WO
Inventors: Udit Bhaveshkumar Shah
Original assignee: Eaton Intelligent Power Ltd
Current assignee: Eaton Intelligent Power Ltd
Priority date: 2023-11-08
Filing date: 2024-11-08
Publication date: 2025-05-15
Anticipated expiration: 2026-05-08

Abstract

A recirculation delivery unit includes a pump and an ejector disposed within a common housing. The ejector path is disposed between the pump path and a motor operating the pump. The pump and the ejector may have a common inlet into the housing and/or a common outlet out of the housing. Fluid passing through the pump may be combined with fluid passing through the ejector before leaving the housing. A heater may be disposed within the ejector to provide de-icing and/or inhibit ice formation.

Description

RECIRCULATION DELIVERY UNIT FOR FUEL CELL

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of Indian Provisional Application Nos. 202311076187, filed November 8, 2023, and 202411082634, filed October 29, 2024, the disclosures of which are hereby incorporated by reference in their entireties.

BACKGROUND

[0002] Traditional automotive vehicles utilize internal combustion engines such as diesel, gas or two stroke engines to propel the vehicle. Electric vehicles with fuel cells require high performance as well as high durability of recirculation systems. In some constructions, a hydrogen recirculation pump recirculates hydrogen into a fuel cell stack. Hydrogen recirculation systems are utilized for increasing fuel use and increasing durability of fuel cell stacks. There is a need for improved recirculation systems that may increase performance, increase durability, reduce parasitic loads, or otherwise increase efficiency of a fuel cell system.

SUMMARY

[0003] Aspects of the disclosure are directed to a recirculation delivery unit and methods of use thereof. The recirculation delivery unit includes a pump and an ejector disposed within a common housing. In certain examples, the ejector is disposed between the pump and a motor operating the pump. In certain examples, the ejector extends between rotatable shafts that operate the pump. Disposing the pump and ejector within a common housing mitigates the size and weight of the housing. Further, a common housing may enhance durability of the recirculation gas flow control and distribution assembly.

[0004] In some implementations, the pump and the ejector share a common outlet from the housing. In certain examples, fluid output from the pump and fluid output from the ejector are combined within the housing prior to exiting through the common outlet.

[0005] In other implementations, the pump and the ejector are disposed in series. In certain examples, the ejector is disposed downstream of the pump. In certain examples, a recirculation inlet and a recirculation outlet of the recirculation delivery unit are disposed at a common side of the recirculation delivery unit.

[0006] In certain implementations, the pump and the ejector share a common inlet into the housing for fluid leaving the fuel cell. In some examples, the ejector and the pump have free access to the fluid entering through the common inlet. In other examples, a valve may control access between the pump and the common inlet.

[0007] In certain implementations, a heater is disposed within the ejector. In certain examples, the heater is controlled based on sensor readings taken at the ejector.

[0008] A variety of additional inventive aspects will be set forth in the description that follows. The inventive aspects can relate to individual features and to combinations of features. It is to be understood that both the forgoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the broad inventive concepts upon which the embodiments disclosed herein are based.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The accompanying drawings, which are incorporated in and constitute a part of the description, illustrate several aspects of the present disclosure. A brief description of the drawings is as follows:

[0010] FIG. 1 is a schematic view of an example fuel cell recirculation system including a recirculation delivery unit configured in accordance with the principles of the present disclosure;

[0011] FIG. 2 is a perspective view of an example implementation of a recirculation delivery unit suitable for use with the fuel cell recirculation system of FIG. 1;

[0012] FIG. 3 is a cross-sectional view of the recirculation delivery unit of FIG. 2 taken along the 3-3 line;

[0013] FIG. 4 shows a valve disposed within an inlet chamber of the circulation delivery unit of FIG. 3;

[0014] FIG. 5 is a cross-sectional view of the recirculation delivery unit of FIG. 2 taken along the 5-5 line;

[0015] FIG. 6 is a cross-sectional view of the recirculation delivery unit of FIG. 2 taken along the 6-6 line;

[0016] FIG. 7 shows a heater and a sensor disposed within the ejector and managed by a control system;

[0017] FIG. 8 shows an example ejector nozzle conduit having a bypass inlet and heater;

[0018] FIG. 9 shows the example ejector nozzle conduit of FIG. 8 having a bypass outlet;

[0019] FIG. 10 shows the ejector nozzle conduit of FIG. 9 having a dedicated path between the bypass inlet and the bypass outlet;

[0020] FIG. 11 shows the ejector nozzle conduit of FIG. 8 having multiple bypass outlets; [0021] FIG. 12 shows an example ejector nozzle conduit having end caps;

[0022] FIG. 13 shows a check valve disposed at the ejector outlet;

[0023] FIG. 14 shows a check valve disposed at a cross-over path from the ejector path to the pump path;

[0024] FIG. 15 illustrates an example valve arrangement that controls fluid access to the ejector inlet and/or the pump inlet;

[0025] FIG. 16 is a perspective view of another example implementation of a recirculation delivery unit suitable for use with the fuel cell recirculation system of FIG. 1;

[0026] FIG. 17 is a cross-sectional view of the recirculation delivery unit of FIG. 16 taken along the 17-17 plane;

[0027] FIG. 18 shows the recirculation delivery unit of FIG. 17 with a first non-retum valve disposed upstream of the ejector nozzle and a second non-return valve disposed at the recirculation outlet.

DETAILED DESCRIPTION

[0028] Reference will now be made in detail to exemplary aspects of the present disclosure that are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

[0029] FIG. 1 shows example fuel cell recirculation systems 200 including a fuel cell stack 202, a recirculation delivery unit 100, 300, a fuel source 204, and a purge valve 206. Hydrogen or other fuel is provided to the fuel cell stack 202 (e.g., to an anode side of the fuel cell stack) at a stack inlet 208 in excess quantity. For example, fuel can be provided from the fuel source 204 via a pressure regulator 214 to the stack inlet 208. Providing an excess quantity of fuel mitigates the chances of fuel starvation and maintains a membrane humidity. Any unutilized fuel leaving the stack outlet 210 is recirculated back to the fuel cell stack 202 via the fuel cell recirculation system 200 to improve fuel utilization and maintain the fuel cell stack efficiency. For example, the recirculation delivery unit 100, 300 (e.g., see FIGS. 2 and 16) combines some of the unreacted fuel leaving the stack outlet 210 with new fuel from the fuel source 204 and then directs the new combined fuel back to the stack inlet 208.

[0030] As shown, the unutilized fuel leaves the stack outlet 210 in an outlet flow that includes both fuel (e.g., hydrogen) and water. In certain cases, the outlet flow also may contain other components (e.g., gaseous nitrogen). In certain implementations, the outlet flow is directed to a water separator 212 that removes the water from the outlet flow and a purge valve 206 that removes undesired gases (e.g., gaseous nitrogen) from the outlet flow. In certain implementations, the recirculation delivery unit 100, 300 includes a pump 108, 308 that pulls a remainder of the outlet flow (or a portion thereof) into the assembly 100, 300 and along a pump path 112, 312 (e.g., see FIGS. 3 and 17). It will be understood that the remaining outlet flow reaching the recirculation delivery unit 100, 300 may include a mixture of unreacted hydrogen (e.g., H2), water vapor, and gaseous nitrogen or a sub-combination thereof.

[0031] Still referring to FIG. 1, in certain implementations, an ejector 105, 305 of the recirculation delivery unit 100, 300 receives pressurized fuel (e.g., pressurized H2) from the fuel source 204. The flow of the received pressurized fuel through the ejector 105, 305 creates a suction force that pulls at least some of the remainder of the outlet flow through the ejector 105, 305 along an ejector path 110, 310 (e.g., see FIGS. 3 and 17). In some implementations, the ejector 105, 305 supplements the recirculation flow generated by the pump 108, 308. In such implementations, outlet flows of the pump 108, 308 and the ejector 105, 305 are combined within the recirculation delivery unit 100, 300 and output towards the inlet 208 of the fuel cell stack 202. In other implementations, the ejector 105, 305 can be used in place of the pump 108, 308. In still other implementations, the pump 108, 308 can be used without the ejector 105, 305.

[0032] Referring to FIGS. 2-7 and 16-17, example recirculation delivery units 100, 300 suitable for use in the fuel cell recirculation system 200 or another recirculation system are shown. The control and distribution assembly 100, 300 includes a housing 102, 302 defining a recirculation inlet 104, 304 and a recirculation outlet 106, 306 (e.g., see FIGS. 3 and 17). The pump 108, 308 is disposed within the housing 102, 302 to direct fluid from the recirculation inlet 104, 304, through a pump inlet 124, 324, along a pump path 112, 312, towards the recirculation outlet 106, 306. In certain examples, the pump 108, 308 includes a pair of parallel, rotatable rotors 118, 318 driven by rotor shafts 116 (e.g., see FIG. 4). The rotor shafts 116 are driven by a motor 120, 320. In certain examples, the pump 108, 308 is a Roots-style pump. Other types of pumps are possible.

[0033] The ejector 105 also is disposed within the housing 102 and defines an ejector path 110. FIGS. 2-7 shows a recirculation delivery unit 100 in which the ejector path 110 extends in parallel with the pump path 112. For example, the flow may split at the inlet 104 so that a portion flows along the ejector path 110 while another portion flows along the pump path 112 as will be described in more detail herein. FIGS. 16-18 show another recirculation delivery unit 300 in which the ejector path 310 is disposed in series with the pump path 312. For example, the flow may enter the housing 102 through the inlet 304, pass along the pump path 312, and then pass along the ejector path 310 before reaching the outlet 306 as will be described in more detail herein.

[0034] Referring to FIGS. 2-7, in certain implementations, the housing 102 defines an ejector path 110 extending from the recirculation inlet 104 to the recirculation outlet 106. The ejector path 110 is separate from the pump path 112. The ejector 105 has a first ejector inlet 126 that receives a portion R of the outlet flow from the recirculation inlet 104 (e.g., see FIG. 7). The ejector 105 also has a second ejector inlet 140 (e.g., see FIG. 7) receiving fuel F from the fuel source 204. The second ejector inlet 140 leads to a nozzle 142 within the ejector 105 to combine the fresh fuel F from the fuel source 204 with the recirculating outlet flow R along the ejector path 110. In certain examples, the flow of the fresh fuel F from the nozzle 142 creates a suction at the first ejector inlet 126 to pull the recirculating outlet flow R into the ejector 105 at the first ejector inlet 126.

[0035] Referring to FIGS. 3 and 4, in certain implementations, the recirculation inlet 104 of the housing 102 leads to an inlet chamber 122 within the housing 102 that is in fluid communication with both the pump inlet 124 of the pump path 112 and the first ejector inlet 126 of the ejector path 110. In some implementations, the inlet chamber 122 is open (e.g., see FIG. 3). In such implementations, the recirculating outlet flow is pulled into the first ejector inlet 126 and the pump inlet 124 from the inlet chamber 122. The amount of outlet flow passing to the pump inlet 124 compared to the first ejector inlet 126 is dependent on the operation speed of the pump 108 and the flow speed of the fuel F through the nozzle 142.

[0036] In other implementations, a valve 128 is disposed within the inlet chamber 122 to selectively open and close access to the pump inlet 124 relative to the recirculation inlet 104 (e.g., see FIG. 4). In such implementations, the first ejector inlet 126 remains freely fluidly accessible from the recirculation inlet 104 so that recirculation flow can be sucked into the ejector 105 by the pressurized fuel flow F. The pump 108 can be utilized to increase the flow speed or pressure of the recirculating outlet flow R by opening the valve 128. In certain implementations, a non-retum valve 129 may be provided upstream of the nozzle 142 to facilitate smooth fluid flow even under high back pressure or similar conditions.

[0037] Referring to FIG. 15, a valve arrangement 216 is configured to selectively open and close access to the first ejector inlet 126. In some examples, the valve arrangement 216 is disposed within the housing 102 of the recirculation delivery unit 100 (e.g., within the inlet chamber 122). In other examples, the valve arrangement 216 is disposed external of the recirculation delivery unit 100. In certain implementations, the valve arrangement 216 includes one or more valves that enable either of the ejector path 110 or the pump path 112 to be opened and/or closed.

[0038] In certain implementations, the valve arrangement 216 is configured to route recirculation flow to the pump path 112 and not to the ejector path 110 during periods of operation in which the recirculation flow has a low flow rate (e.g., volume flow rate). For example, the valve arrangement 216 may direct the recirculation flow to the pump 108 during initial operation of recirculation system (e.g., when the vehicle is started). The valve arrangement 216 also may direct the recirculation flow to the pump 108 when a low power load is being drawn from the stack 202.

[0039] When a rate of the recirculation flow increases to a first predetermined threshold (e.g., when additional power is desired from the fuel cell stack 202), the valve arrangement 216 opens or begins to open access to the ejector path 110 and closes or begins to close access to the pump path 112. Accordingly, the recirculation flow is driven by the ejector 105 after reaching the first predetermined threshold. If the recirculation flow rate drops back below the first predetermined threshold, then the valve arrangement 216 may switch or transition the recirculation flow back to the pump 108.

[0040] In certain implementations, if the recirculation flow rate continues to increase to a second predetermined threshold that is greater than the first predetermined threshold, then the valve arrangement 216 may re-open or begin to open the pump path 112 so that both the pump 108 and ejector 105 are cooperating to drive the recirculation flow. Accordingly, the pump 108 can be sized smaller than would be otherwise necessary to accommodate a maximum output from the recirculation delivery device 100. Allowing for a smaller size pump enables the recirculation delivery device 100 to have a compact shape and/or low weight for the flow rate produced.

[0041] In some examples, the recirculation flow rate is determined as a ratio between a rate of the recirculation flow exiting the fuel cell stack 202 and a rate of the recirculation flow entering the fuel cell stack 202 (e.g., the flow rate sensed at the stack outlet 210 divided by the flow rate sensed at the stack inlet 208). In other examples, the recirculation flow rate is determined by dividing the flow rate sensed at the recirculation inlet 104 by the flow rate sensed at the recirculation outlet 106. In other implementations, the valve arrangement 216 is controlled based on the pressure ratio between the stack outlet 210 and the stack inlet 208.

[0042] Referring back to FIGS. 3 and 4, in some implementations, the recirculation inlet 104 extends parallel or coaxial with the ejector path 110. For example, the recirculation inlet 104 may align with the ejector path 110. Accordingly, the ejector path 110 extends linearly between the recirculation inlet 104 and the recirculation outlet 106. In another example, the recirculation inlet 104 and/or the recirculation outlet 106 may align with the pump path 112. In other examples, the recirculation inlet 104 and/or recirculation outlet 106 may be disposed at an intermediate location between the ejector path 110 and the pump path 112. In other implementations, the recirculation inlet 104 may be tangential, orthogonal, or otherwise angled relative to the ejector path 110.

[0043] In certain examples, the pump path 112 has an intermediate portion that extends generally linearly. In certain examples, the intermediate portion of the pump path 112 is parallel to the ejector path 110 (e.g., see FIG. 2). In certain implementations, the recirculation inlet 104 is offset from the intermediate portion of the pump path 112. The pump path 112 extends from the recirculation inlet 104, through the inlet chamber 122 at an angle to the ejector path 110, and then angles or curves through the pump inlet 124. In certain implementations, the recirculation inlet 104 is the only entrance into the inlet chamber 122 from an exterior of the housing 102.

[0044] In certain implementations, both a pump outlet 134 of the pump path 112 and an ejector outlet 136 of the ejector path 110 lead to an outlet chamber 132 within the housing 102. The flow from the ejector path 110 (e.g., including the fresh fuel F) and the flow from the pump path 112 combine within the outlet chamber 132. The outlet chamber 132 is in fluid communication with the recirculation outlet 106. In some implementations, the recirculation outlet 106 aligns with the ejector path 110 and is offset from at least the intermediate portion of the pump path 112. In other implementations, the recirculation outlet 106 aligns with the pump path 112. In other implementations, the recirculation outlet 106 is disposed at an intermediate location between the ejector path 110 and the pump path 112. In certain implementations, the recirculation outlet 106 is the only outlet from the outlet chamber 132 to an exterior of the housing 102. Utilizing common inlets and/or outlets reduces the possible sources of leakage from the housing.

[0045] Referring to FIGS. 16-18, in certain implementations, the housing 302 defines the recirculation inlet 304 and the recirculation outlet 306 at a common side of the housing 302. In certain examples, the recirculation inlet 304 and the recirculation outlet 306 face in opposite directions at the same side of the housing 302. In certain examples, the housing 302 defines an intermediate chamber 307 at an opposite side of the housing 302 from the recirculation inlet 304 and the recirculation outlet 306. In certain examples, one or more sensors can be disposed within the intermediate chamber 307. For example, a humidity sensor and/or a pressure sensor may be disposed within the intermediate chamber 307. In certain examples, the intermediate chamber 307 may define a water outlet port.

[0046] In certain examples, the pump path 312 and the ejector path 310 are disposed in series between the recirculation inlet 304 and the recirculation outlet 306. In the example shown, the ejector path 310 is disposed downstream of the pump path 312. For example, the pump path 312 leads from the recirculation inlet 304 to the intermediate chamber 307 and the ejector path 310 leads from the intermediate chamber 307 to the recirculation outlet 306.

[0047] In certain examples, the recirculation inlet 304 of the housing 302 leads to a pump inlet 324 of the pump path 312. The pump path 312 extends across the housing 302 to a pump outlet 334, which outputs into the intermediate chamber 307 at the second side of the housing. The ejector path 310 has a first ejector inlet 326 that receives the outlet flow from the pump outlet 334. The ejector 305 also has a second ejector inlet 140 (e.g., see FIG. 7) receiving fuel F from the fuel source 204. The second ejector inlet 140 leads to a nozzle 142 within the ejector 305 to combine the fresh fuel F from the fuel source 204 with the recirculating flow from the pump path outlet 334 along the ejector path 310. In certain examples, the flow of the fresh fuel F from the nozzle 142 creates a suction at the first ejector inlet 326 to pull the recirculating outlet flow into the ejector 305 at the first ejector inlet 326.

[0048] The ejector outlet 336 outputs to the recirculation outlet 306. In certain implementations, a non-retum valve 329 may be provided upstream of the nozzle 142 to facilitate smooth fluid flow even under high back pressure or similar conditions. In certain implementations, a check valve or other non-retum valve 388 can be disposed at the recirculation outlet 306 to inhibit back flow.

[0049] As shown in FIGS. 3-6 and 16-18, the pump path 112, 312 and the ejector path 110, 310 can be defined by a common housing 102, 302. In certain examples, the ejector path 110, 310 is adjacent the pump path 112, 312 (e.g., see FIGS. 3, 4, and 17). In certain examples, the ejector path 110, 310 shares a common wall 150, 350 with the pump path 112, 312 (e.g., see FIGS. 3 and 17). In certain examples, the ejector 105, 305 is not separable from the housing 102, 302. In certain examples, the ejector 105, 305 is fully contained within a footprint of the housing 102, 302 of the recirculation delivery unit 100, 300. In certain examples, the ejector 105, 305 is fully contained within the housing 102, 302 that extends between the pump 108, 308 and the motor 120, 320. In some implementations, the ejector 105, 305 is disposed between the pump 108, 308 and the motor 120, 320. In certain implementations, the ejector 105, 305 extends between the pair of rotor shafts 118 as the rotor shafts extend from the pump 108, 308 to the motor 120, 320 (e.g., see FIGS. 5 and 6). In other implementations, the ejector 105, 305 can be otherwise disposed (e.g., at an opposite side of the pump 108, 308 from the motor 120, 320 or at an opposite side of the motor 120, 320 from the pump 108, 308).

[0050] In certain implementations, by positioning the ejector 105, 305 between the pump 108, 308 and the motor 120, 320, at least part of the ejector path 110, 310 is protected from ambient temperatures. For example, the ejector inlet 126 and the ejector outlet 136 are recessed within the housing 102 from the recirculation inlet 104 and the recirculation outlet 106, respectively. In the example shown in FIG. 17, the ejector inlet 326 only received fluid after the fluid has passed through the pump path 312 and the ejector outlet 336 is recessed inwardly from the recirculation outlet 306. In certain implementations, a heater 144 can be added to the ejector 105, 305 to further inhibit freezing of the flow along the ejector path 110, 310 (e.g., see FIG. 7). For example, the heater 144 may provide sufficient heat to the flow through the ejector 105, 305 to inhibit ice formation within the ejector 105, 305 and/or to melt ice formation within the ejector 105, 305.

[0051] In certain implementations, heat from the heater 144 transfers to the fresh hydrogen flowing through the ejector 105, 305. In certain examples, the heat inhibits ice buildup within the ejector 105, 305. In certain implementations, the heat from the heater 144 transfers from the flow along the ejector path 110, 310, through the common wall 150, 350, to the flow along the pump path 112, 312. In certain examples, the heat inhibits ice buildup within the pump 108, 308. In certain examples, the heat inhibits ice buildup within the housing 102, 302 of the recirculation delivery unit 100, 300. In certain examples, the heat inhibits ice buildup within conduits extending downstream of the recirculation outlet 106, 306. In certain examples, the heat breaks up ice buildup (e.g., melts the ice) as well as inhibits additional ice buildup.

[0052] Referring to FIG. 7, in certain implementations, the second ejector inlet 140 is formed as a conduit 145 extending through a portion of the housing 102, 320 at an angle to the ejector path 110, 310. In certain examples, the conduit 145 may extend out of the housing 102, 302 to define the second ejector inlet 140 external of the housing 102, 302. The conduit 145 is fluidly coupled to the nozzle 142, which directs fluid (e.g., fuel F) into the ejector path 110, 310. In certain examples, the conduit 145 has a first portion extending into the housing 102, 302 from the inlet 140 and a second portion that extends towards the nozzle 142. In certain examples, the first and second portions are transverse to each other. In certain implementations, the conduit 145 extends out of the housing 102, 302 to define both the first ejector inlet 140 and a third ejector inlet 146, which will be described in more detail below with respect to FIGS. 8-11. [0053] In certain examples, the heater 144 also is disposed within the conduit 145. In certain examples, the heater 144 is sealed within a chamber adjacent or within the conduit 145. In certain examples, the conduit 145 has a T-shape. For example, the heater 144 may be formed at an opposite side of the conduit 145 from the inlet port 140 while the ejector nozzle 142 extends outwardly from an intermediate portion of the conduit 145.

[0054] In certain implementations, the heater 144 is managed by a control system 220 (e.g., an electronic controller). For example, a sensor 152 may be disposed within the ejector 105, 305 (e.g., see FIG. 7). In some examples, the sensor 152 is disposed at the second ejector inlet 140. In other examples, the sensor 152 is disposed along the ejector path 110. The sensor 152 providing a data signal 222 to the control system 220. In some examples, the data signal 222 indicates a temperature of the fluid flowing through the ejector 105, 305. In other examples, the data signal 222 indicates the fluid flow rate through the ejector 105, 305. In certain examples, the control system 220 may receive data signals from multiple sensors (e.g., sensors at multiple locations within the housing 102 and/or multiple types of sensors). From the data signal 222, the control system 220 determines whether ice has formed or is likely to form within the ejector 105, 305. The control system 220 sends a command signal 224 to the heater 144 to activate and deactivate based on the determination.

[0055] In some examples, the control system 220 may check the sensor readings during a cold start of a vehicle powered by the fuel cell stack 202. The control system 220 may activate the heater 144 if the sensor reading indicates ice has formed while the vehicle was parked. In other examples, the control system 220 may periodically check the sensor reading during operation of the vehicle.

[0056] Referring to FIGS. 8-11, in certain implementations, the conduit 145 leading to the nozzle 142 includes a third inlet 146 (e.g., a bypass inlet). In certain examples, fresh hydrogen also may be directed to the third inlet 146 to enhance the flow through the ejector 160. In some implementations, fresh fuel (e.g., fresh hydrogen) is directed to the second ejector inlet 140 from the fuel source 204 while fresh fuel is directed to the third inlet 146 from a separate fuel source 204a. In other implementations, the fresh fuel may be directed to both inlets 140, 146 from a common fuel source using different injectors, different pressure regulators, and/or different pathways between the fuel source and the ejector 105, 305.

[0057] In certain implementations, the second and third inlets 140, 146 are configured to receive different flow rates (e.g., have different sizes). In an example, the third inlet 146 is smaller to receive a lower flow rate. In other examples, the third inlet 146 is the same size or larger than the second inlet 140. In some examples, the low-rate flow is directed within the conduit 145 to the nozzle 142 and then into the ejector path 110, 310. In other examples, the low-rate flow from the third inlet 146 is directed to a separate outlet 147. For example, the outlet 147 allows the flow to bypass the nozzle 142 to inhibit drawing recirculation fluid to the first inlet 126. In other examples, however, the bypass outlet 147 can be used to supplement fresh hydrogen passing through the nozzle 142 by introducing additional flow.

[0058] In some implementations, the second ejector outlet 147 is aligned with the third ejector inlet 146. In other implementations, the second ejector outlet 147 is offset along the conduit 145 from the third ejector inlet 146. In certain examples, the bypass outlet 147 of the conduit does not have a converging and then diverging design. In various examples, the bypass outlet 147 has a converging design, a diverging design, or a straight design. In other examples, the bypass outlet 147 of the conduit forms a second nozzle having a converging-diverging design.

[0059] In some implementations, the conduit 145 is configured so that flow through the third inlet 146 can access both the nozzle 142 and the bypass outlet 147 (e.g., see FIG. 9). In other implementations, the conduit 145 is configured so that the flow through the third inlet

146 is directed to only the outlet 147 (e.g., see FIG. 10). In certain such implementations, a wall of the conduit 145 blocks a path between the third inlet 146 and the nozzle 142. In certain examples, the wall also seals the heater 144 from the flow while allowing heat to transfer to the flow through the wall. In some implementations, the outlet 147 is a single port (e.g., hole, tub, etc.) offset along the conduit 145 from the nozzle 142. In other implementations, the outlet

147 may include multiple ports defined by the conduit with each of the multiple ports being offset from the nozzle 142 (e.g., see FIG. 11).

[0060] In some implementations, the third ejector inlet 146 is parallel to the ejector path 110, 310. In other implementations, however, the third ejector inlet 146 may extend at a nonzero angle relative to the ejector path 110, 310. In certain examples, the third ejector inlet 146 may extend between 30 degrees and 60 degrees relative to the ejector path 110, 310. In certain examples, the third ejector inlet 146 may extend between 5 degrees and 45 degrees relative to the ejector path 110, 310. In certain examples, the third ejector inlet 146 may extend between 45 degrees and 85 degrees relative to the ejector path 110, 310. In certain examples, the third ejector inlet 146 may be transverse to the ejector path 110, 310.

[0061] In some operating modes or phases, the flow through the third inlet 146 may supplement the flow through the second inlet 140 at the nozzle 142. In other operating modes or phases, the conduit 145 receives fresh fuel through only the third inlet 146 (i.e., bypass inlet). For example, fresh fuel may be directed through the ejector 105, 305 at the bypass inlet 146 and not at the first inlet 140 to avoid creating suction that would draw recirculation flow through the ejector 105, 305. Instead, the bypass inlet 146 can be utilized to provide fresh fuel to the fuel stack 202 before a sufficient amount of recirculation flow has built up or when power loads are sufficiently low to not support a recirculation flow through the ejector 105, 305. In some examples, the valve arrangement 216 may close off the first inlet 126 of the ejector 105 when the fresh fuel is supplied to the bypass inlet 146. In other examples, the first ejector inlet 126, 326 may remain unblocked while fresh fuel is provided to the bypass inlet 146.

[0062] In certain implementations, the heater 144 is disposed at the third ejector inlet 146. In such implementations, fresh fuel may be run through the third inlet 146 for the purpose of heating the flow within the ejector 105, 305. The low-rate flow through the third inlet 146 is heated by the heater 144. In certain examples, the heated flow then passes through and heats the nozzle 142. In certain examples, the heated flow passes through the one or more outlets 147 to distribution the heated flow throughout the ejector 105, 305 either instead of or in addition to passing through the nozzle 142. In certain examples, the heat from the low-rate flow can pass through the shared wall 150, 350 or other structure to other parts of the recirculation delivery unit 100, 300.

[0063] FIG. 12 illustrates one example multi -piece construction 160 of an ejector conduit 145. The multi-piece conduit 160 includes a main body 162 and at least a first end cap 164. The main body 162 includes a section 168 extending along a first direction and a second section 170 extending along a second direction. In certain examples, the second direction is angled (e.g., at a non-zero angle, orthogonal, at a 45 degree angle, etc.) relative to the first direction. The second section 170 extends outwardly from an intermediate location along the first section 168. The second section 170 defines the nozzle 142 of the ejector conduit 145.

[0064] In certain implementations, the first end cap 164 defines the second ejector inlet 140. In certain examples, the conduit 160 also includes a second end cap 166. In some examples, the second end cap 166 holds the heater 144. For example, the second end cap 166 may seal the heater 144 from the first section 168 of the main body 162. In other examples, the second end cap 166 defines the third inlet 146. In another example, the third inlet 146 is defined by the main body 162.

[0065] In certain examples, the end cap(s) 164, 166 are releasably mounted to the main body 162. In an example, the end cap(s) 164, 166 are threaded onto the main body 162. In other examples, the end cap(s) 164, 166 can be snap-fit, fastened, press-fit, or otherwise connected to the main body 162. In still other examples, the end cap(s) 164, 166 can be non- releasably mounted to the main body, e.g., by welding, gluing, etc. In still other implementations the ejector conduit 145 may be an monolithically formed part.

[0066] As shown in FIGS. 13 and 14, in certain implementations, the recirculation delivery unit 100, 300 includes a check valve 188 at or near the recirculation outlet 106, 306. The check valve 188 inhibits backflow into the ejector 105, 305 through the ejector outlet 136, 336. In some implementations, the check valve 188 is disposed at the ejector outlet 136, 336 (e.g., see FIG. 13). In other implementations, the check valve 188 is disposed at the outlet chamber 132. In still other implementations, the ejector path 110 can be directed into the pump path 112 so that the recirculation flow combines in the pump path 112. For example, a crossover path 190 may extend from the ejector outlet 136 to an intermediate section of the pump path 112. In certain examples, the intermediate section is upstream of, but adjacent the pump outlet 134. In certain implementations, the pump outlet 134 may form the recirculation outlet 106. In certain implementations, the check valve 188 can be disposed within the cross-over path 190 (e.g., see FIG. 14).

[0067] Examples of the disclosure may be described according to the following aspects.

[0068] Aspect 1. A recirculation delivery unit comprising:

[0069] a housing defining a recirculation inlet and a recirculation outlet, the housing also defining an ejector path and a separate pump path extending from the recirculation inlet to the recirculation outlet; and

[0070] a pump disposed within the housing to direct flow from the recirculation inlet along the pump path to the recirculation outlet, the pump including a pair of rotatable rotors driven by rotor shafts;

[0071] the ejector path of the housing extending between the pair of rotor shafts of the pump.

[0072] Aspect 2. The recirculation delivery unit of aspect 1, wherein the ejector path aligns with the recirculation inlet.

[0073] Aspect 3. The recirculation delivery unit of aspect 1 or aspect 2, wherein the ejector path aligns with the recirculation outlet.

[0074] Aspect 4. The recirculation delivery unit of any of aspects 1-3, wherein the pump path extends parallel to the ejector path.

[0075] Aspect 5. The recirculation delivery unit of any of aspects 1-4, further comprising a check valve disposed between the pump path and the ejector path.

[0076] Aspect 6. The recirculation delivery unit of any of aspects 1-5, further comprising a heating element in fluid communication with the ejector path. [0077] Aspect 7. The recirculation delivery unit of aspect 6, further comprising:

[0078] a sensor disposed within the ejector path, the sensor providing a data signal;

[0079] an electronic controller configured to receive the data signal, the electronic controller also configured to manage operation of the heating element.

[0080] Aspect 8. The recirculation delivery unit of aspect 8, wherein the sensor includes a pressure sensor and wherein the data signal includes a pressure signal.

[0081] Aspect 9. The recirculation delivery unit of any of aspects 6-8, wherein the heating element directly opposes a second inlet of the ejector path, the second inlet being fluidly coupled to a pressurized source.

[0082] Aspect 10. The recirculation delivery unit of any of aspects 1-6, wherein the ejector path has a second inlet configured to direct a pressurized flow into the ejector path, the pressurized flow entering the housing at a non-zero angle relative to the ejector path.

[0083] Aspect 11. The recirculation delivery unit of aspect 10, wherein the second inlet faces in a direction transverse to the ejector path.

[0084] Aspect 12. The recirculation delivery unit of any of aspects 1-11, wherein the housing is devoid of outlets in communication with the pump path and the ejector path beyond the recirculation outlet.

[0085] Aspect 13. The recirculation delivery unit of any of aspects 1-12, wherein the pump is operated by a motor attached to the housing.

[0086] Aspect 14. The recirculation delivery unit of any of aspects 1-13, wherein the ejector path is disposed between the pump path and the motor.

[0087] Aspect 15. The recirculation delivery unit of any of aspects 1-14, wherein the recirculation inlet is fluidly coupled to a water separator that is external of the housing.

[0088] Aspect 16. The recirculation delivery unit of any of aspects 1-15, wherein the recirculation outlet is fluidly coupled to a fuel cell stack that is external of the housing.

[0089] Aspect 17. A method of recirculating hydrogen within a fuel cell system, the method comprising:

[0090] pumping recirculation fluid from a fuel cell into a first inlet of a housing;

[0091] dividing the recirculation fluid within the housing so that a first portion of the fluid flows along a first path and a second portion of the fluid flows along a second path;

[0092] routing pressurized fluid from a pressurized source into a second inlet of the housing and then to the second path to combine with the second portion of the recirculation fluid, the second inlet being separate from the first inlet, the pressurized source being separate from the fuel cell; and [0093] combining the first and second portions of the recirculation fluid within the housing to form a combined flow and outputting the combined flow from the housing through an outlet of the housing.

[0094] Aspect 18. The method of aspect 17, further comprising heating the pressurized fluid to disperse heat throughout the second path.

[0095] Aspect 19. The method of aspect 18, further comprising dispersing heat from the second path to the first path through a common wall.

[0096] Aspect 20. The method of aspect 18, wherein heating the pressurized fluid is performed in response to sensing an ice blockage within the second path.

[0097] Aspect 21. The method of any of aspects 17-20, wherein the second path passes between rotors of a pump that performs the pumping step.

[0098] Aspect 22. An ejector comprising:

[0099] an ejector body extending along an ejector path between a first ejector inlet and an ejector outlet; and

[0100] a conduit coupled to the ejector body, the conduit defining a second ejector inlet that is separate from the first ejector inlet, the conduit also defining a nozzle leading to the ejector path, the conduit including a main body and a first end cap, the first end cap defining the second ejector inlet.

[0101] Aspect 23. The ejector of aspect 22, further comprising a second end cap coupled to the main body of the conduit.

[0102] Aspect 24. The ejector of aspect 23, wherein the second end cap holds a heater.

[0103] Aspect 25. An ejector comprising:

[0104] an ejector body extending along an ejector path between a first ejector inlet and an ejector outlet; and

[0105] a conduit coupled to the ejector body, the conduit defining a second ejector inlet that is separate from the first ejector inlet, a third ejector inlet that is separate from both the first and second ejector inlets, the conduit also defining a nozzle leading to the ejector path.

[0106] Aspect 26. The ejector of aspect 25, wherein the third ejector inlet is smaller than the second ejector inlet.

[0107] Aspect 27. The ejector of aspect 25 or aspect 26, wherein the conduit also defines a bypass outlet separate from the nozzle.

[0108] Aspect 28. The ejector of aspect 27, wherein the conduit defines an isolated path between the third ejector inlet and the bypass outlet. [0109] Aspect 29. The ejector of aspect 27, wherein the conduit defines a routing path between the third ejector inlet and the nozzle.

[0110] Aspect 30. A method of recirculating hydrogen within a fuel cell system, the method comprising:

[OHl] pumping recirculation fluid from a fuel cell into an inlet at a first side of a housing;

[0112] using a pump, directing the recirculation fluid along a first path within the housing from the first inlet to an intermediate chamber;

[0113] directing the recirculation fluid from the intermediate chamber into a second path using suction created by routing pressurized fluid from a pressurized source into the second path, thereby combining the recirculation fluid with the pressurized fluid to form a combined fluid, the pressurized source being separate from the fuel cell; and

[0114] directing the combined fluid to an outlet at the first side of the housing.

[0115] Aspect 31. The method of aspect 30, wherein the second path extends parallel to the first path.

[0116] Aspect 32. The method of aspect 30 or aspect 31, wherein the first and second paths share a common wall of the housing.

[0117] Aspect 33. The method of any of aspects 30-32, wherein the inlet aligns with the first path and the outlet aligns with the second path.

[0118] Aspect 34. The recirculation delivery unit of aspect 1, wherein the pump path and the ejector path extend in parallel between the recirculation inlet at a first side of the housing and the recirculation outlet at an opposite side of the housing.

[0119] Aspect 35. The recirculation delivery unit of aspect 34, further comprising a check valve disposed between a pump outlet of the pump path and an ejector outlet of the ejector path.

[0120] Aspect 36. The recirculation delivery unit of aspect 1, wherein the pump path and the ejector path are disposed in series.

[0121] Aspect 37. The recirculation delivery unit of aspect 36, wherein the recirculation inlet and the recirculation outlet are disposed at a common side of the housing.

[0122] Having described the preferred aspects and implementations of the present disclosure, modifications and equivalents of the disclosed concepts may readily occur to one skilled in the art. However, it is intended that such modifications and equivalents be included within the scope of the claims which are appended hereto.

Claims

What is claimed is:

1. A recirculation delivery unit comprising: a housing defining a recirculation inlet and a recirculation outlet, the housing also defining an ejector path and a separate pump path extending from the recirculation inlet to the recirculation outlet; and a pump disposed within the housing to direct flow from the recirculation inlet along the pump path to the recirculation outlet, the pump including a pair of rotatable rotors driven by rotor shafts; the ejector path of the housing extending between the pair of rotor shafts of the pump.

2. The recirculation delivery unit of claim 1, wherein the pump path and the ejector path extend in parallel between the recirculation inlet at a first side of the housing and the recirculation outlet at an opposite side of the housing.

3. The recirculation delivery unit of claim 2, further comprising a check valve disposed between a pump outlet of the pump path and an ejector outlet of the ejector path.

4. The recirculation delivery unit of claim 1, wherein the pump path and the ejector path are disposed in series.

5. The recirculation delivery unit of claim 4, wherein the recirculation inlet and the recirculation outlet are disposed at a common side of the housing.

6. The recirculation delivery unit of any of claims 1-5, further comprising a heating element in fluid communication with the ejector path.

7. The recirculation delivery unit of claim 6, further comprising: a sensor disposed within the ejector path, the sensor providing a data signal; an electronic controller configured to receive the data signal, the electronic controller also configured to manage operation of the heating element.

8. The recirculation delivery unit of any of claims 1-6, wherein the ejector path has a second inlet configured to direct a pressurized flow into the ejector path, the pressurized flow entering the housing at a non-zero angle relative to the ejector path.

9. The recirculation delivery unit of any of claims 1-8, wherein the housing is devoid of outlets in communication with the pump path and the ejector path beyond the recirculation outlet.

10. The recirculation delivery unit of any of claims 1-9, further comprising an ejector conduit extending between a second inlet for the ejector path and a nozzle leading to the ejector path.

11. The recirculation delivery unit of claim 10, wherein the ejector conduit is formed of multiple pieces.

12. A method of recirculating hydrogen within a fuel cell system, the method comprising: pumping recirculation fluid from a fuel cell into a first inlet of a housing; dividing the recirculation fluid within the housing so that a first portion of the fluid flows along a first path and a second portion of the fluid flows along a second path; routing pressurized fluid from a pressurized source into a second inlet of the housing and then to the second path to combine with the second portion of the recirculation fluid, the second inlet being separate from the first inlet, the pressurized source being separate from the fuel cell; and combining the first and second portions of the recirculation fluid within the housing to form a combined flow and outputting the combined flow from the housing through an outlet of the housing.

13. A method of recirculating hydrogen within a fuel cell system, the method comprising: pumping recirculation fluid from a fuel cell into an inlet at a first side of a housing; using a pump, directing the recirculation fluid along a first path within the housing from the first inlet to an intermediate chamber; directing the recirculation fluid from the intermediate chamber into a second path using suction created by routing pressurized fluid from a pressurized source into the second path, thereby combining the recirculation fluid with the pressurized fluid to form a combined fluid, the pressurized source being separate from the fuel cell; and directing the combined fluid to an outlet at the first side of the housing.

14. An ejector comprising: an ejector body extending along an ejector path between a first ejector inlet and an ejector outlet; a conduit coupled to the ejector body, the conduit defining a second ejector inlet that is separate from the first ejector inlet, the conduit also defining a nozzle leading to the ejector path, the conduit including a main body and a first end cap, the first end cap defining the second ejector inlet.

15. An ejector comprising: an ejector body extending along an ejector path between a first ejector inlet and an ejector outlet; and a conduit coupled to the ejector body, the conduit defining a second ejector inlet that is separate from the first ejector inlet, a third ejector inlet that is separate from both the first and second ejector inlets, the conduit also defining a nozzle leading to the ejector path.

16. The ejector of claim 15, wherein the third ejector inlet is smaller than the second ejector inlet.

17. The ejector of claim 15 or claim 16, wherein the conduit also defines a bypass outlet separate from the nozzle.

18. The ejector of claim 17, wherein the conduit defines an isolated path between the third ejector inlet and the bypass outlet.

19. The ejector of claim 17, wherein the conduit defines a routing path between the third ejector inlet and the nozzle.

20. The ejector of claim 14, further comprising a second end cap coupled to the main body of the conduit, wherein the second end cap holds a heater.