US-12626942-B2 - Integrated fuel cell injection unit using additive manufacturing

US12626942B2US 12626942 B2US12626942 B2US 12626942B2US-12626942-B2

Abstract

Aspects of integrated hydrogen fuel cell injection units herein use additive manufacturing to form a single part. A space between a body and an ejector nozzle/venturi tube system forms an attenuation volume. The heat exchanger is integrated within the attenuation volume, saving space. The ejector nozzle/venturi tube, and the stack anode inlet to the fuel cell, are arranged through the heat exchanger and allow an injector at the base of the body to selectively emit hydrogen into the anode of the fuel cell. This architecture obviates the need for many O-rings and bolts used in present fuel injection systems using existing manufacturing techniques that may be unduly large and unwieldy and that may cause hydrogen leakage at different connection points.

Inventors

Joseph Hahn
Patrick J. Eding

Assignees

GM Global Technology Operations LLC

Dates

Publication Date: 20260512
Application Date: 20230614

Claims (20)

1 . An additively manufactured hydrogen fuel cell injection unit, comprising: a body comprising a noise attenuation volume integrated therein, a first end of the body comprising an aperture for mounting an injector; an ejector assembly including an ejector tube and a stack anode inlet positioned at a second end of the body, the stack anode inlet configured to inject hydrogen into a fuel cell; a heat exchanger integrated within the noise attenuation volume and comprising a triply periodic minimal surface (TPMS) lattice of unit cells arranged therein, the TPMS lattice being configured to heat hydrogen flowing therethrough, each end surface of the heat exchanger separated from the first and second ends of the body by a respective volume; and an ejector nozzle coupled to an interior of the body and aligned with the injector near the first end of the body, the ejector nozzle surrounded by a gap, the gap leading to a recycle path inlet of the body for recapturing residual hydrogen proximate the recycle path inlet, wherein the ejector tube protrudes through the heat exchanger and is aligned with the ejector nozzle such that the ejector tube passes hydrogen through the stack anode inlet.
2 . The additively manufactured hydrogen fuel cell injection unit of claim 1 , wherein the hydrogen that passes to the fuel cell from the stack anode inlet includes (1) pressurized hydrogen sourced from the injector, (2) the residual hydrogen proximate the recycle path inlet, and (3) the hydrogen exiting the heat exchanger.
3 . The additively manufactured hydrogen fuel cell injection unit of claim 1 , wherein: the second end of the body comprises an inlet coupled to a hydrogen source; the volume between a first end surface of the heat exchanger and the first end of the body is a first volume; the volume between a second end surface of the heat exchanger and the second end of the body is a second volume; and the second end surface of the heat exchanger is shaped in a geometrical gradient configured to enable the hydrogen received from the inlet at the second end of the body to distribute evenly in the second volume when entering and passing through the heat exchanger to enable a uniform heat increase of the hydrogen.
4 . The additively manufactured hydrogen fuel cell injection unit of claim 1 , wherein: a first end surface of the heat exchanger and the first end of the body define a first volume into which heated hydrogen exiting the heat exchanger flows; and the first end surface of the heat exchanger is shaped to form a gradient for a more even distribution of the heated hydrogen as the heated hydrogen exits the heat exchanger into the first volume.
5 . The additively manufactured hydrogen fuel cell injection of claim 4 , wherein the gradient is shaped at least partly conical.
6 . The additively manufactured hydrogen fuel cell injection unit of claim 1 , wherein the TPMS lattice comprises a plurality of unit cells forming two channels, wherein a first channel passes hydrogen through the heat exchanger and a second channel passes a fluid to heat the hydrogen.
7 . The additively manufactured hydrogen fuel cell injection unit of claim 6 , wherein a side of the body includes two apertures for passing the fluid through the second channel of the heat exchanger.
8 . The additively manufactured hydrogen fuel cell injection unit of claim 1 , wherein the injector is configured to selectively activate to controllably pass hydrogen flowing from a volume proximate the first end of the body through the ejector nozzle and the ejector tube for emission into the fuel cell.
9 . The additively manufactured hydrogen fuel cell injection unit of claim 1 , wherein the ejector tube comprises a venturi tube, the venturi tube and the injector being configured to create a low pressure in the gap to pull the residual hydrogen into the gap through a recycle path inlet and through the ejector tube into the fuel cell via the stack anode inlet.
10 . An additively manufactured fuel cell injection unit, comprising: a body having a noise attenuation volume therein; a first end of the body including an aperture for mounting a hydrogen injector; an ejector assembly including an ejector tube coupled to a stack anode inlet, the stack anode inlet positioned at a second end of the body for injecting hydrogen into a fuel cell; a heat exchanger comprising a lattice of unit cells integrated within the noise attenuation volume, the lattice being configured to heat hydrogen flowing therethrough, each end surface of the heat exchanger separated from the first and second ends of the body by a respective volume, a surface of the heat exchanger being adjacent each respective volume including a gradient; an ejector nozzle coupled to an output of the injector at the first end of the body, the ejector nozzle surrounded by a gap, the gap leading to a recycle path inlet of the body for recapturing excess hydrogen; and an ejector tube protruding through the heat exchanger and aligned with the ejector nozzle such that the ejector tube is configured to pass hydrogen via the stack anode inlet to the fuel cell.
11 . The additively manufactured hydrogen fuel cell injection unit of claim 10 , wherein one or both of the surfaces of the heat exchanger adjacent the respective volumes are at least partly conical in shape.
12 . The additively manufactured hydrogen fuel cell injection unit of claim 10 , wherein the injector is selectively activated to inject hydrogen from a source into the ejector nozzle to eject hydrogen from the stack anode inlet into the fuel cell via the ejector tube and to create a low pressure region in the gap for recapturing the excess hydrogen.
13 . The additively manufactured hydrogen fuel cell injection unit of claim 12 , wherein the injector is further configured to guide the heated hydrogen exiting the heat exchanger into the volume proximate the first end into the ejector nozzle and thereafter into the ejector tube.
14 . The additively manufactured hydrogen fuel cell injection unit of claim 12 , further comprising a plurality of pressure sensors co-printed with the ejector assembly, wherein the injector is cyclically activated to inject the hydrogen when the pressure drops below a threshold.
15 . The additively manufactured hydrogen fuel cell injection unit of claim 10 , wherein the body comprises an additively manufactured (AM) body, and wherein the AM body and integrated noise attenuation volume and heat exchanger are formed as a single, integral unit to eliminate use of elastomeric seals.
16 . The additively manufactured hydrogen fuel cell injection unit of claim 10 , wherein elements of the body are designed to avoid sharp angles and abruptly changing edges and to instead form curved portions.
17 . The additively manufactured hydrogen fuel cell injection unit of claim 10 , wherein the ejector tube includes a venturi tube formed using additive manufacturing without a draft angle.
18 . A method for additively manufacturing a fuel injector unit, comprising: forming a body having at least a partly cylindrical shape and defining an acoustic attenuation volume therein; printing a venturi tube extending longitudinally along at least a part of the body from a first end to a second end, a stack anode inlet at the second end to inject hydrogen into a fuel cell; printing an ejector nozzle aligned with the venturi tube at the first end for selectively injecting hydrogen into the venturi tube; enclosing the ejector nozzle within a gap that extends to an aperture in a surface of the body, the gap used for recovering unused hydrogen for emission via the ejector nozzle and the venturi tube into the stack anode inlet; integrating a heat exchanger into the acoustic attenuation volume, the heat exchanger comprising a lattice of unit cells arranged between the venturi tube and a perimeter of the body, such that a first surface of the heat exchanger adjacent the first end includes a gradient bounding a first volume at the first end and a second surface of the heat exchanger adjacent the second end includes a gradient bounding a second volume with the second end, wherein hydrogen entering an inlet aperture in the second surface flows through the heat exchanger from the second volume to the first volume; and forming an aperture in the first end for mounting an injector, the injector being configured to selectively emit hydrogen from the first volume and from an injector through the ejector nozzle and into the venturi tube for entry into the fuel cell at the stack anode inlet.
19 . The method of claim 18 , wherein the first or second surface of the heat exchanger is at least partly conical in shape.
20 . The method of claim 18 , wherein the body further includes a coolant input for injecting coolant into a channel of the heat exchanger, and a coolant output for receiving the coolant from the heat exchanger.

Description

INTRODUCTION An injection unit may be used to controllably inject a fuel, such as hydrogen, into a fuel cell of a vehicle in order to generate electricity and propel the vehicle via an electric motor. One advantage of a hydrogen-fueled vehicle is that, unlike gasoline-controlled combustion engines that emit carbon monoxide, the primary byproduct of a hydrogen system is water vapor, thereby eliminating most toxic emissions. Injection units typically function by injecting a fuel, such as hydrogen, into the anode portion of a hydrogen fuel cell (or stack), within which an electricity-producing combustion reaction occurs. Prior to actual injection of hydrogen into the fuel cell, various preparation steps are taken using different connected components. For example, the hydrogen is heated using a heat exchanger. Noise is muffled via an attenuator. The hydrogen is also mediated to an appropriate pressure and velocity using various nozzles and injection elements. These elements may assist in reconstituting unused hydrogen from a prior cycle and in injecting hydrogen into the fuel cell using a streamlined ejector assembly. Modern fuel cell injection units are bulky and unwieldy, and susceptible to hydrogen leakage. To connect the different components of the injection unit together, bolts and O-rings are needed. The bulky noise attenuator is especially subject to leakage, and complex forging techniques are often employed to combat this phenomenon. These injection units may still have a number of points where leakage is significant. Because regular isotopes of hydrogen atoms consist of a single proton and a single electron (often bonded in molecular form to another such atom), the fuel is physically very small and permeates through the smallest apertures. Leakage is particularly abundant in elastomeric seals such as the O-rings, which are commonly used in injection units, and other connectors between different components. This leakage contributes to fuel loss and an increase in unwanted hydrogen emissions. SUMMARY In one aspect of the present disclosure, an additively manufactured hydrogen fuel cell injection unit includes a body including a noise attenuation volume, a first end of the body including an aperture for mounting an injector; an ejector assembly including an ejector tube and a stack anode inlet positioned at a second end of the body, the stack anode inlet configured to inject hydrogen into a fuel cell; a heat exchanger integrated within the noise attenuation volume and including a triply-periodic minimal surface (TPMS) lattice of unit cells arranged therein, the TPMS lattice being configured to heat hydrogen flowing therethrough, each end surface of the heat exchanger separated from the first and second ends of the body by a respective volume; and an ejector nozzle coupled to an interior of the body and aligned with the injector at the first end of the body, the ejector nozzle surrounded by a gap, the gap leading to a recycle path inlet of the body for recapturing residual hydrogen proximate the recycle path inlet; wherein the ejector tube protrudes through the heat exchanger and is aligned with the ejector nozzle such that the ejector tube passes the hydrogen to the stack anode inlet. In various aspects, the hydrogen passed to the stack anode inlet includes (1) pressurized hydrogen sourced from the injector nozzle, (2) the residual hydrogen in the gap, and (3) the hydrogen exiting the heat exchanger. The second end of the body includes an inlet for receiving hydrogen from a source. A volume between the first end surface of the heat exchanger and the first end of the body defines a first volume. A second end surface of the heat exchanger adjacent the second volume is shaped in a geometrical gradient configured to enable the leftover hydrogen received at the inlet at the second end of the body to evenly distribute across the second volume when entering the heat exchanger to enable a uniform heat increase of the hydrogen. In various embodiments, the second end surface of the heat exchanger is proximate to the second volume into which the hydrogen flows. The first end surface of the heat exchanger defines a lower part of the first volume and is shaped to form a gradient for a more even distribution of the heated hydrogen. In an embodiment, the gradient is shaped at least partly conical. The TPMS lattice includes a plurality of unit cells having two channels, wherein a first channel passes hydrogen through the heat exchanger and a second channel passes a fluid to heat the hydrogen. In various embodiments, a side of the body includes two apertures for passing fluid through the second channel of the heat exchanger. The ejector nozzle may be configured to selectively activate to controllably pass hydrogen flowing from a heat exchanger surface proximate the first end of the body through the ejector tube for emission into the fuel cell. Activation of the injector is configured to create a low pressure zone in the g