Apparatus and method for removing target gas from a refrigerated environment

Abstract

The present invention is entitled "Device and method for removing target gas from a refrigerated environment". Various embodiments relate to an improved electrochemical cell system configured to reduce the concentration of a target gas in a refrigerated environment. The electrochemical cell system may include an electrochemical cell device, an air circulation device, and a flow hood. The electrochemical cell device may be combined with or coupled to the air circulation device via the flow hood to maximize the entry of the target gas into the air holes.

Description

Background Art

[0001] Gas removal techniques are commonly used to "clean" or remove the presence of various target gases from an environment. Applicants have identified many deficiencies and problems associated with conventional gas removal techniques. Through effort, ingenuity, and innovation, solutions developed in accordance with embodiments of the present disclosure have addressed many of these identified deficiencies and problems, many examples of which are described in detail herein. Summary of the invention

[0002] Various embodiments provided herein disclose improved methods, apparatus, and systems for removing or reducing the concentration of a target gas to an optimal level in a refrigerated environment.

[0003] Some embodiments relate to an electrochemical cell system configured to reduce the concentration of a target gas in a refrigerated environment, comprising: an electrochemical cell device, the electrochemical cell device comprising a housing having an air hole, a first electrode and a second electrode disposed within the housing, wherein the device is configured to receive the target gas through the air hole, at least partially electrochemically oxidize the target gas when in contact with a surface of the first electrode to form one or more reaction products, and spread at least a portion of the one or more reaction products through the air hole, thereby reducing the concentration of the target gas; an air circulation device; and a flow hood, wherein the electrochemical cell device is coupled to the air circulation device via the flow hood, the flow hood defining a flow path for the target gas to flow across the air hole of the electrochemical cell device. In some embodiments, the flow hood may be configured so that it generates turbulence of the target gas through the flow hood.

[0004] In some embodiments, the flow hood is configured such that it generates a turbulent flow of the target gas through the flow hood. In yet other embodiments, the flow hood includes one or more protrusions in the flow path.

[0005] In some embodiments, the electrochemical cell device may further include a third electrode. In still other embodiments, the electrochemical cell device may further include a fourth electrode.

[0006] In various embodiments, the device may further include one or more electrolyte separators disposed between the first electrode and the second electrode. In yet other embodiments, the first electrode may include a first gas permeable membrane and a first catalyst mixture, and the first electrode may be positioned within the housing so that the target gas passes through the first gas permeable membrane before reaching the first catalyst mixture. In yet other embodiments, at least one of the electrodes may include gold or a gold alloy. In various embodiments, the target gas may include ethylene, hydrogen sulfide, or a combination thereof.

[0007] In some embodiments, the air circulation device may be a fan. In other embodiments, the air circulation device may be a pump.

[0008] In various embodiments, the electrochemical cell system may further include an electronic circuit configured to measure the current generated by the electrochemical cell device. In yet other embodiments, the air circulation device may be configured so that it is activated when the current generated by the electrochemical cell device meets a predetermined threshold. In certain embodiments, the electrochemical cell system may further include a timer, and wherein the air circulation device may be configured so that it is activated when a defined time period measured by the timer expires.

[0009] In yet further embodiments, the electrochemical cell system may further include a high surface area carbon filter.

[0010] The details of one or more embodiments of the subject matter described in this specification are set forth in the following drawings and description. Other features, aspects, and advantages of the subject matter will be apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Having thus generally described some embodiments, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and in which:

[0012] Figure 1A shows a cross-sectional schematic diagram of an exemplary device structured according to various embodiments disclosed herein;

[0013] Figure 1B Schematic diagrams showing exemplary devices structured according to various embodiments disclosed herein;

[0014] Figure 2A shows a cross-sectional schematic diagram of an exemplary electrochemical cell device structured according to various embodiments disclosed herein;

[0015] Figure 2Bshows a cross-sectional schematic diagram of an exemplary electrochemical cell device structured according to various embodiments;

[0016] Figure 3A shows a schematic diagram of an exemplary electrochemical cell system structured according to various embodiments disclosed herein;

[0017] Figure 3B shows a schematic diagram of an exemplary electrochemical cell system structured according to various embodiments disclosed herein;

[0018] Figure 4 shows a schematic diagram of an exemplary electronic circuit that can be used to measure the current generated by an electrochemical cell device structured according to various embodiments disclosed herein;

[0019] Figure 5 shows a schematic diagram of two working electrodes structured according to one embodiment disclosed herein;

[0020] Figure 6 shows a schematic diagram of two working electrodes structured according to one embodiment disclosed herein;

[0021] Fig. 7A shows current readings of an exemplary electrochemical cell device according to various embodiments disclosed herein;

[0022] Figure 7B shows current readings of an exemplary electrochemical cell device according to various embodiments disclosed herein;

[0023] Fig. 8A shows current readings of an exemplary electrochemical cell device according to various embodiments disclosed herein;

[0024] Figure 8B shows current readings of an exemplary electrochemical cell device according to various embodiments disclosed herein; and

[0025] Fig. 9 Methods of reducing the concentration of a target gas in an environment according to various embodiments disclosed herein are shown. DETAILED DESCRIPTION

[0026] The present disclosure describes various embodiments more fully below with reference to the accompanying drawings, in which some but not all embodiments of the present disclosure are shown. In fact, these disclosures can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; on the contrary, these embodiments are provided so that the present disclosure satisfies applicable legal requirements. Throughout the content, similar reference numerals refer to similar elements. The terms used in this article are not meant to be limiting, and the devices or apparatus described herein, or portions thereof, may be attached or utilized in other orientations.

[0027] The term "comprising" means including but not limited to, and should be interpreted in the manner commonly used in the patent context. It should be understood that the use of broad terms such as "comprising," "including," and "having" provides support for narrower terms such as "consisting of," "consisting essentially of," and "composed essentially of."

[0028] The phrases "in one embodiment," "according to one embodiment," "in some examples," and the like generally mean that the particular feature, structure, or characteristic following the phrase may be included in at least one embodiment of the present disclosure, and may be included in more than one embodiment of the present disclosure (importantly, such phrases do not necessarily refer to the same embodiment).

[0029] The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other implementations.

[0030] The terms "about" or "approximately" and the like, when used with a number, can mean the specific number, or alternatively, a range approximate to the specific number as understood by those skilled in the art.

[0031] If the specification states that a component or feature "may", "can", "could", "should", "will", "preferably", "likely", "usually", "optionally", "for example", "often", or "might" (or other such words) be included or have a property, the particular component or feature is not required to be included or have that property. Such components or features may optionally be included in some embodiments, or may be excluded.

[0032] Overview

[0033] Ethylene has been identified as a plant hormone and is known to have significant effects on plant physiology throughout the plant life cycle. The presence of ethylene, even at low concentrations, in refrigerated environments (such as refrigerated trucks, refrigerated rail cars, and refrigerated drop shipping or transport containers) commonly used for post-harvest and distribution of many horticultural products is generally considered to be detrimental to the quality and longevity of such horticultural products.

[0034] It has been demonstrated that removing ethylene from a refrigerated environment to ensure the freshness of fruits, vegetables and flowers is difficult, and prior art filters and systems for eliminating ethylene are generally ineffective, require frequent replacement, result in increased costs, and / or involve hazardous materials. For example, applications that rely on simple ventilation methods result in increased operating costs, applications that utilize potassium permanganate require frequent replacement and hazardous waste disposal, applications that utilize ultraviolet radiation and / or ozone (e.g., corona discharge systems) require maintenance and involve potential toxic exposures, and applications that rely on physical adsorbents require frequent replacement. Due to at least these reasons, it is desirable to effectively reduce the concentration of ethylene present in a refrigerated environment without incurring repeated costs or significant exposure risks, especially in household applications (i.e., consumer or residential refrigeration appliances such as refrigerators).

[0035] Various exemplary embodiments of the present disclosure relate to systems, methods, and apparatus configured to provide improved removal of target gases using electrochemical cell devices. As discussed herein, applicants have determined that providing an electrochemical cell device according to various exemplary embodiments disclosed herein facilitates electrochemical oxidation of target gases, thereby reducing the concentration of target gases in an identified environment without incurring ongoing maintenance or replacement costs and without risk of exposure to hazardous waste or toxic gases.

[0036] Exemplary apparatus for implementing various embodiments

[0037] The electrochemical cell devices disclosed herein may be in any suitable form. Figure 1A A schematic cross-sectional view of an exemplary electrochemical cell device 100 structured according to various embodiments is shown. In the embodiment shown, the device 100 includes a housing 105 having a pore 110 where a gas, such as a target gas, can enter the device 100. The housing is formed of any chemically compatible material, such as plastic, metal, and ceramic. In certain embodiments, the housing is plastic.

[0038] exist Figure 1A In the illustrated embodiment, the device 100 includes two electrodes, including a working electrode 115 and a counter electrode 120. In such embodiments, the counter electrode 120 operates as both a counter electrode and a reference electrode (i.e., the counter electrode / reference electrode 120). Alternatively or additionally, in some embodiments, such as Figure 1B As shown, the device 100 includes three electrodes, including a working electrode 115, a counter electrode 120, and a separate reference electrode 125. The reference electrode 125 can be located in the center of the electrochemical cell stack as shown, or interchanged with the counter electrode 120.

[0039] In various embodiments, the electrodes are electrically connected to each other via one or more electrical connectors 155. For example, in Figure 1A In the two-electrode embodiment shown, the electrodes 115, 120 are electrically connected to each other by electrical connectors 155. In some embodiments, the one or more electrical connectors 155 are chemically inert and electrochemically inert under the operating conditions of the electrochemical cell device 100. In certain embodiments, the electrical connectors 155 are made of platinum. In other embodiments, the electrical connectors 155 are made of tantalum.

[0040] One or more electrolyte separators 130 are disposed between the electrodes. Figure 1A In the dual electrode embodiment shown, the working electrode 115 is in contact with a first surface of the electrolyte separator 130, and the counter electrode / reference electrode 120 is in contact with a second surface of the electrolyte separator 130. Figure 1B In the non-limiting exemplary three-electrode embodiment shown, the working electrode 115 is in contact with the first electrolyte separator 130, the first electrolyte separator 130 is also in contact with the cross barrier 135, the cross barrier 135 is also in contact with the reference electrode 125, the reference electrode 125 is also in contact with the second electrolyte separator 130, the second electrolyte separator 130 is also in contact with the counter electrode 120, and the counter electrode is also in contact with the third electrolyte separator. The one or more electrolyte separators 130 include an ion-conductive electrolyte maintained in a porous substrate material, that is, the porous substrate material can become saturated with electrolyte to accommodate ion transfer therebetween. Common electrolytes can be used, including soluble salts, acids (e.g., sulfuric acid, phosphoric acid), alkalis, etc., depending on the target gas of interest. According to various embodiments described herein, sulfuric acid is used. The porous substrate material may include non-woven materials, woven materials, polymer films, etc. In some embodiments, the porous substrate material is formed by glass fibers.

[0041] In some embodiments, one or more cross-barriers 135 may be interspersed within the one or more electrolyte separators 130. Although the one or more electrolyte separators 130 provide a gas barrier between the electrodes 115, 120, 125, the one or more cross-barriers 135 are optionally included to provide additional barriers to prevent the target gas from reaching the counter electrode / reference electrode 120 in a two-electrode embodiment, and the counter electrode 120 and the reference electrode 125 in a three-electrode embodiment. That is, the one or more cross-barriers 135 are configured so that they form a path between the working electrode 115 and the counter electrode / reference electrode 120 (or the counter electrode 120 and the reference electrode 125 in the three-electrode embodiment) on the one hand, and on the other hand, are more tortuous to limit any reaction products from the electrochemical oxidation of the target gas from reaching the counter electrode / reference electrode 120 (and the counter electrode 120 and the reference electrode 125 in the three-electrode embodiment). In some embodiments, the cross-barriers are formed of a chemically inert polymer film, such as a polyvinylidene chloride (PVDC) film or polychlorotrifluoroethylene (PCTFE).

[0042] return Figure 1A , the working electrode 115 includes a first gas permeable membrane 140 and an electrode catalyst mixture 141, wherein the first gas permeable membrane 140 is disposed between the pores 110 and the catalyst mixture 141. In some embodiments, the first gas permeable membrane 140 includes a porous hydrophobic substrate to support the electrode catalyst mixture 141 when forming an electrode, as described in more detail below. The porous hydrophobic substrate allows the target gas to enter the electrode catalyst mixture 141 through the first gas permeable membrane 140. In certain embodiments, the gas permeable hydrophobic substrate includes microporous polytetrafluoroethylene (PTFE). Each electrode may include such a gas permeable membrane and an electrode catalyst mixture.

[0043] The material and configuration of the electrode can vary based on the specific type of target gas to be eliminated from the environment. That is, when maintained at an appropriate electrode potential, the electrode may include a reactive material suitable for promoting the electrochemical oxidation of the target gas. For example, the electrode may include one or more materials, such as platinum, palladium, iridium, rhodium, ruthenium, gold, silver, carbon, a combination thereof, their oxides and / or their alloys. As a non-limiting illustrative example, in a household refrigeration application where ethylene is the target gas, gold or a gold alloy may be a preferred electrode catalyst mixture 141, so that the working electrode 115 reacts with the expected ethylene gas while remaining insensitive to other ambient gases (such as carbon monoxide). A single electrode may have the same material or different materials. For example, in some embodiments, all electrodes are formed of the same material. In other embodiments, the electrode is formed of different materials.

[0044] According to various embodiments, each of the electrodes 115, 120, 125 is made by depositing an electrode catalyst mixture (such as high surface area noble metal catalyst particles intimately mixed with a binder (such as PTFE particles)) onto a gas permeable membrane. For example, the working electrode 115 can be made by depositing an electrode catalyst mixture 141 comprising a high surface area noble metal catalyst onto a first gas permeable membrane 140. In certain embodiments, the above deposition can be achieved using any suitable deposition method, including but not limited to electrochemical deposition, spray deposition, vacuum deposition, wet chemical deposition, screen printing, etc., or a combination thereof.

[0045] In some embodiments, the thickness of the deposited electrode catalyst mixture may be varied in order to provide improved performance to one or more electrodes. For example, one electrode may contain a heavier or thicker catalyst deposit than the other electrode. According to various dual electrode embodiments, such as Figure 1A As shown, the working electrode 115 and the counter electrode 120 are electrically shorted together, and the working electrode potential is determined by the "mixed potential" of both the working electrode 115 and the counter electrode 120. In such embodiments, in order to impart long-term stability and minimize electrode polarization when the electrochemical cell device 100 actively removes a target gas from an environment, in some examples, the counter electrode 120 may be formed by depositing a thicker layer or layers of an electrode catalyst mixture layer, thereby obtaining a thicker catalyst layer (compared to the thickness of the electrode catalyst mixture 141 in the working electrode 115).

[0046] In various embodiments, the electrochemical cell device 100 may optionally include one or more dust films 175, such as Figure 1B As shown. A dust film 175 may be desirable to reduce exposure of the electrochemical cell device to dust particles and other physical contaminants. In still other embodiments, the electrochemical cell device 100 may include one or more seals, such as an O-ring 180 or a PTFE seal 185. In certain embodiments, a colored identification ring 190 may be provided to identify the target gas detected by the electrochemical cell device.

[0047] The electrochemical cell devices disclosed herein may be positioned in any environment where one or more target gases are present and it is desired to remove them, such as in a home or consumer appliance (e.g., a household refrigerator). Although the examples disclosed herein are generally described in conjunction with refrigerated environments and horticultural applications, those of ordinary skill in the art will understand and should appreciate that the applicability of the disclosed systems, methods, and devices includes a variety of environments and applications, including but not limited to consumer, commercial, aviation, medical, industrial, manufacturing, refineries, agriculture, government, etc.

[0048] The target gas may include one or more gases that are desired to be removed from the environment or controlled in concentration in the environment by the electrochemical cell device. The electrochemical cell device may be used to oxidize a single target gas, two target gases, or multiple target gases. For example, the target gas may include ethylene, carbon monoxide, or hydrogen sulfide, or a combination thereof. One or more electrochemical cell devices may be used in combination, such as a plurality of electrochemical cell devices, each of which is configured to detect a certain target gas or the same target gas.

[0049] See also Figure 1A and Figure 1B In some embodiments and during operation, the target gas is introduced into the electrochemical cell device 100 as the target gas passes through and through the pores 110 of the housing 105, wherein the target gas continues to diffuse through the first gas permeable membrane 140 of the working electrode 115 before reaching the surface of the electrode catalyst mixture 141. At the working electrode 115, the target gas is electrochemically oxidized. In a non-limiting exemplary example, the electrode catalyst mixture 141 of the working electrode 115 includes platinum, and the target gas is ethylene, which is electrochemically oxidized into a mixture of reaction products including carbon dioxide, ethanol, acetic acid, and various other products. In some embodiments, the reaction products leave the electrochemical cell device 100 through the first gas permeable membrane 140 and the pores 110 of the housing 105. In other embodiments, one or more of the reaction products may be dissolved to varying degrees in the electrolyte of the electrolyte separator 130. In a non-limiting exemplary example in which the target gas is ethylene, carbon dioxide may leave through the pores 110, while ethanol, acetic acid, and various other reaction products may be dissolved in the electrolyte of the electrolyte separator 130.

[0050] The current generated during the electrochemical oxidation flows through the electrical connector 155 to maintain the electrical properties between the electrodes 115 and 120. In such an embodiment, the electrochemical cell device is active and continues to remove any gas that reaches the surface of the electrode catalyst mixture 141 of the working electrode 115 and can be electrochemically oxidized. In the depicted embodiment, no power supply or circuit is required. The simplicity of the depicted embodiment and the absence of toxic substances and hazardous wastes required by some existing gas removal technologies make it attractive for refrigeration applications, but it is particularly suitable for consumer or residential refrigeration applications. In some embodiments, the depicted specific implementation is positioned in a home or residential refrigerator, wherein the refrigerator includes a device for circulating the air in the refrigerated compartment.

[0051] In the above-mentioned non-limiting exemplary electrochemical cell device in which ethylene is the target gas, in some examples, the electrochemical cell device as described herein can remove the target ethylene at a rate (e.g., consumption rate) faster than the rate at which food and / or horticultural products can generate ethylene (e.g., decomposition rate). The limitation on the consumption rate of the target gas is the natural convection in the storage compartment. That is, the target gas can be generated by horticultural products, but cannot be fully distributed throughout the storage compartment to contact the electrochemical cell device so as to be electrochemically oxidized. Therefore, in order to enhance the efficacy of the electrochemical cell device, some embodiments disclosed herein utilize forced convection. According to various embodiments, the electrochemical cell device as described herein is arranged relative to one or more air circulation devices such as pumps, fans, blowers, suction equipment, etc. In one embodiment, the air circulation device is arranged away from the electrochemical cell device. In such embodiments, the air circulation device can be independently powered by a refrigeration unit or a battery source.

[0052] In another embodiment, the air circulation device is disposed adjacent to the electrochemical cell device and is coupled to the device via one or more conduits such as tubing, etc. For example, the air circulation device may be directly attached to the device using tubing. In such embodiments, the air circulation device may be independently powered by a refrigeration unit or a battery source.

[0053] In another embodiment, the electrochemical cell device and the air circulation device are configured such that they operate as a standalone system. Figure 2A A schematic cross-sectional view of an exemplary electrochemical cell device 200 structured according to various embodiments is shown. In the illustrated embodiment, an air circulation device (not shown) is coupled to the device via a flow housing or flow hood 201. The flow housing or flow hood 201 is configured such that it generates a turbulent flow of gas (i.e., air including the target gas) across the air holes 210, such as Figure 2A In some embodiments, as shown by the arrow in Figure 2B As shown, the flow housing or flow cover 201 includes one or more protrusions 211 (such as ribs) in the flow path to generate turbulence. Compared with the diffusion or laminar flow of the target gas through the air holes 110, such turbulence is configured to maximize the entry of the target gas through the air holes 210 and increase the target gas removal efficiency (i.e., increase the consumption rate) of the electrochemical cell device 200. In various embodiments, the flow housing or flow cover 201 is constructed of one or more materials that can be machined or molded. In some embodiments, the flow housing or flow cover 201 is constructed of plastic. In various embodiments, the flow housing or flow cover 201 is constructed of molded ceramic. In some embodiments, the flow housing or flow cover 201 includes metal. In such embodiments, direct metal surfaces can be avoided to avoid promoting condensation in the flow cover 201 or the air holes 210.

[0054] Figure 3A A schematic diagram of an exemplary electrochemical cell system 300 structured according to various embodiments is shown. In some embodiments, a stand-alone electrochemical cell system 300 including an air circulation device 303 and an electrochemical cell device 304 will also include a separate power source 302 (such as a rechargeable battery source) electrically connected to the air circulation device 303. In some embodiments, the overall size of the electrochemical cell system will be configured so that it will easily fit into the refrigeration compartment of a home refrigeration unit. Figure 3A As shown, in some embodiments, the air circulation device 303 (such as a pump) includes one or more inlets 306 and one or more outlets 307 connected to the refrigeration compartment so that it recirculates the air in the refrigeration compartment. In another embodiment, the air circulation device 303 (such as a small fan) is directly connected to the electrochemical cell device 304, so that the electrochemical cell device 304 and the air circulation device 303 operate as an independent electrochemical cell system 300.

[0055] In various embodiments, the air circulation device 303 is configured to operate continuously. That is, the air circulation device 303 circulates the air in the environment continuously and passes through the air holes of the electrochemical cell device. In some embodiments, the air circulation device 303 is configured to operate intermittently for a sufficient period of time so that the air in the refrigerated compartment will be recirculated several times.

[0056] In some embodiments, activation of the air circulation device 303 is triggered by an event or procedure. For example, Figure 3B A schematic diagram of an exemplary electrochemical battery system 300 structured according to various embodiments is shown. In the illustrated embodiment, the independent electrochemical battery system 300 includes a timer 308 or is otherwise associated with a timer to control the power cycle and operating frequency of the air circulation device 303. When the limited time period expires, the air circulation device 303 is configured to activate. The power cycle (i.e., on-off cycle) and the operating frequency will depend on the type and capacity of the air circulation device and the volume of the refrigerated compartment, whereby such time and frequency conditions can be predetermined by a technician through a certain routine experiment. In addition or alternatively, in certain embodiments, the air circulation device 303 is configured so that it is activated (i.e., turned on) when the door of the refrigeration compartment and / or the refrigerator is opened. In some embodiments, the refrigerator door may be associated with the electrochemical battery system 300 and / or the air circulation device 303 so that an activation event (e.g., opening the door) generates a signal transmitted to the air circulation device 303.

[0057] In such embodiments, the configuration of the air circulation device 303 does not require detection of any measurement of the sample gas to initiate activation. That is, in some embodiments, the air circulation device 303 can be activated and recirculate air even in the absence of the target gas in the refrigerated environment.

[0058] In various embodiments, the air circulation device 303, the electrochemical cell system 300, and / or the electrochemical cell device 100, 200, 304 can be configured so that the air circulation device 303 is subject to active control (rather than passive control as described with respect to various embodiments herein). Therefore, it may be desirable to save energy and operate the air circulation device 303 in the event that the target gas is present and needs to be removed. In some embodiments, the electrochemical cell device 100, 200, 304 includes an electronic circuit 400 so that it measures the current generated by the electro-oxidation of the target gas in the electrochemical cell device 100, 200, 304. Figure 4 A schematic diagram of an exemplary electronic circuit 400 that can be used to measure the current generated by an electrochemical cell device structured according to various embodiments is shown. In still other embodiments, the air circulation device 303 is configured so that it is activated when the current generated by the electrochemical cell device 100, 200, 304 meets (i.e., exceeds) a predetermined threshold. In such embodiments, the electrochemical cell device detects the target gas in addition to removing the target gas, thereby eliminating the need for additional hardware.

[0059] Such a predetermined threshold value may be determined in a variety of ways, depending on the importance of minimizing the presence of unwanted gases versus reducing the operation of the air circulation device 303 (i.e., saving energy). For example, in some embodiments, the predetermined threshold value is defined as the level of the highest apparent gas concentration expected to be found when testing replicates of a sample gas that does not contain the target gas analyte. This value is often referred to as the "limit of blank (LOB)" and is estimated experimentally by measuring replicates of a blank sample gas and calculating the average result and standard deviation (SD), and is given by the following equation (1):

[0060] (1) LOB = mean blank + 1.645 (SD blank)

[0061] The predetermined threshold is set at the LOB to keep the risk of operating the air circulation device 303 when the target gas is not necessarily present to a minimum level of unwanted gas.

[0062] Additionally or alternatively, in various embodiments, the predetermined threshold is defined as a limit of detection (LOD) according to the following equation (2):

[0063] (2) LOD = LOB + 1.645 (SD low concentration sample)

[0064] The "SD Low Concentration" is determined by making repeated measurements of the target gas at or near the lowest concentration of interest.

[0065] In some embodiments, the electrochemical cell device does not distinguish between the detection of target gas and other electroactive gases. That is, the current generated by the electrochemical cell device indicates that at least one unwanted electroactive gas (i.e., not necessarily the target gas) is detected in the refrigerated compartment. For example, in a non-limiting illustrative example, in a home refrigeration application where ethylene is the target gas and the electrode catalyst mixture 141 of the working electrode 115 includes platinum, the electrochemical cell device will "clean" or remove any electroactive gas that can be electrochemically oxidized at the surface of the platinum working electrode 115, not just the target ethylene gas. In many home environments, the ambient concentration of other electroactive gases such as carbon monoxide that can be oxidized by platinum may exist at a concentration between about 100 and about 1000 times the maximum expected concentration of ethylene. In such embodiments, the electrochemical cell device may generate a current greater than a predetermined threshold (e.g., LOB, LOD, etc.). Therefore, in some embodiments where the associated air circulation device relies on feedback from the current reading of the electrochemical cell device, the current generated by the electrochemical cell device is sufficient to activate the air circulation device so that the expected target gas is removed from the environment (i.e., the concentration of the target gas is reduced), however, the air circulation device may be continuously activated.

[0066] For the purpose of illustration only and not limitation, several embodiments described herein refer to a two-electrode embodiment having a working electrode 115 and a counter electrode 120, wherein the counter electrode 120 is used as a combined counter electrode / reference electrode 120. In an alternative three-electrode embodiment including a working electrode 115, a counter electrode 120, and a reference electrode 125, the working electrode 115 may be operated at a potential other than 0.0V relative to the reference electrode 125. That is, various embodiments including three electrodes may be operated at different voltages. In some embodiments, the working electrode 115 may be configured to operate at an optimal voltage (relative to the reference electrode 125) to facilitate the fastest consumption of the target gas. For example, in a non-limiting exemplary example in which the reference electrode 125 includes platinum, the operating voltage will be more anode-wise between about 0mV-300mV, preferably between about 250mV-300mV. In such embodiments, the upper limit of the operating voltage is limited by the electrolyte decomposition starting to produce oxygen. In various embodiments including three or more electrodes, electrostatic circuits such as those commonly used in the electrochemical industry can be used with electrochemical cell devices.

[0067] In some embodiments, it is desirable for the electrochemical cell device to distinguish between the detection of the target gas and other electroactive gases in order to avoid continuous activation of the associated air circulation device. That is, in various embodiments in which the current generated by the electrochemical cell device provides feedback to the air circulation device, it may be desirable for the generated current to indicate the response of the electrochemical cell device to the target gas rather than the target gas and other electroactive gases. For example, in a non-limiting illustrative example, in a home refrigeration application where ethylene is the target gas, gold or a gold alloy may be a preferred catalyst so that the working electrode 115 selectively reacts with the expected ethylene gas while remaining insensitive to other ambient gases (such as carbon monoxide).

[0068] In various embodiments, the electrochemical cell device includes four electrodes, including a first working electrode, a second working electrode, a reference electrode, and a counter electrode. The second working electrode is selected so that it does not react with the target gas of interest and other possible cross-interferants (e.g., such as carbon monoxide when the target gas is ethylene). In such embodiments, the measured value of the current on the first working electrode can be compared with the measured value of the current on the second working electrode, and the resulting difference in response can be attributed to the presence of the target gas. In some embodiments, the first working electrode and the second working electrode share a gas permeable membrane. That is, the first electrode catalyst mixture 515 is applied to a portion of one side of the gas permeable membrane, and the second electrode catalyst mixture 516 is applied to the remainder of the same side of the gas permeable membrane (subject to separation of the catalyst mixture), such as Figure 5 In other embodiments, the second working electrode 616 may be disposed between the first working electrode 615 and the cross barrier 635, such as Figure 6 As shown. Various different combinations of working electrode catalysts are possible and contemplated by the present disclosure. For purposes of illustration and not limitation, the first working electrode may include platinum and the second working electrode may include gold. The choice of catalyst mixture for each working electrode is selected to maximize the gas response to the desired target gas.

[0069] exist Fig. 7A and Figure 7B An exemplary electrochemical cell device according to various embodiments described herein is shown in FIG. Specifically, but not limited to, Fig. 7A and Figure 7B Shown from Figure 6 Current readings of an exemplary experimental electrochemical cell apparatus are shown illustrating the response of a first working electrode 615 comprising a gold catalyst and a second working electrode 616 comprising a platinum catalyst to a mixture of carbon monoxide and ethylene. Fig. 7A It is shown that the first working electrode 615 including the gold catalyst has a large specificity for ethylene, while Figure 7BA second working electrode 616 comprising a platinum catalyst is shown responsive to both gases. In such implementations, an associated air circulation device (not shown) will only be activated when a response is measured at the first working electrode 615 (gold), indicating the presence of the target gas ethylene. Fig. 7A and Figure 7B It is also shown that ethylene generates a simultaneous response at the first working electrode and the second working electrode. Therefore, various embodiments including two working electrodes in such a configuration can be considered to achieve more effective removal of target gases compared to electrochemical cell devices including only one working electrode. In some embodiments, such a configuration allows compensation for transient changes in environmental conditions such as temperature and humidity (which otherwise may be erroneously interpreted as caused by the presence of unwanted gases) and long-term drift of the baseline over time.

[0070] exist Fig. 8A and Figure 8B An exemplary electrochemical cell device according to various embodiments described herein is shown in FIG. Specifically, but not limited to, Fig. 8A and Figure 8B Current readings from an exemplary experimental electrochemical cell apparatus are shown, illustrating the effectiveness of various embodiments described herein. Fig. 8A and Figure 8B 1 shows the current readings (measured in seconds) over time for an electrochemical cell device having three electrodes according to various embodiments described herein, which was placed in a sealed 1 L container initially filled with air and then with 1 ppm of ethylene added. That is, Fig. 8A For example, from time 0 to about 5995 seconds, a "zero" reading corresponds to the presence of air alone. At about 5995 seconds, 1 ppm of ethylene is added to the container, forming an ethylene / air mixture, causing the current reading to rise. Figure 8B A similar "zero" reading was shown, following the addition of 1 ppm ethylene. Fig. 8A Shown are current readings in a static environment. Figure 8B The current readings in a container are shown, wherein the air / ethylene gas mixture is circulated via a small fan placed in the container away from the electrochemical cell arrangement. As shown, Figure 8B The effectiveness of incorporating air circulation devices and / or air turbulence, thereby increasing airflow through the air holes of the electrochemical cell device, is demonstrated.

[0071] In addition or alternatively, in various embodiments, the air circulation device 303, the electrochemical cell system 300 and / or the electrochemical cell device 100, 200, 304 may include a filter. In some embodiments, a filter such as a high surface area (HSA) carbon filter removes potential catalyst poisons. For example, although the HSA carbon filter cannot effectively remove ethylene from the environment, the HSA filter adsorbs gases such as hydrogen sulfide and many organic pollutants. In some embodiments, before the air contacts the pores 110 of the electrochemical cell device 100, 200, 304, one or more filters are positioned in the air flow including the target gas. For example, one or more filters may be arranged in the air circulation device 303, in the inlet of the electrochemical cell system 306 and / or in the flow housing or flow hood 201. In some embodiments, the filter is used in combination with an electrode formed by any catalyst. In yet other embodiments, the electrochemical cell device 100, 200, 304 can be selective for ethylene by using a gold catalyst in combination with an HSA carbon filter to adsorb hydrogen sulfide.

[0072] Example Process

[0073] Having described various embodiments of electrochemical cell devices and systems, it should be appreciated that the electrochemical cell devices and / or systems may proceed to reduce the concentration of a target gas in an environment in a variety of ways.

[0074] Fig. 9 is a flow chart that broadly illustrates a series of steps of a method 900 that is performed using an electrochemical cell apparatus to reduce the concentration of a target gas in an environment according to one embodiment of the present disclosure.

[0075] exist Fig. 9 In the illustrated embodiment, method 900 includes: generating a turbulent flow of a target gas across an opening of an electrochemical cell at step 902; contacting a surface of a first electrode of the electrochemical cell with the target gas at step 904, wherein the first electrode is configured to selectively electrochemically oxidize the target gas into one or more reaction products; and dispersing at least a portion of the one or more reaction products through the opening of the electrochemical cell into the turbulent flow at step 906. At step 908, method 900 optionally contemplates measuring an amount of current generated by the electrochemical cell, and at step 910, activating an air circulation device if the amount of current meets a predetermined threshold.

[0076] Therefore, the specific embodiment of this theme has been described. Although this specification includes many specific implementation details, these details should not be interpreted as limiting any invention or the scope of the content that can be claimed, but should be interpreted as a description of specific features for the specific embodiment of a specific invention. In addition, although specific features can be disclosed using only one of several implementations, such features can be combined with one or more other features of other implementations, as may be expected or advantageous for any given or specific application. Some features described herein in the context of a separate embodiment can also be implemented in combination in a single embodiment. On the contrary, the various features described in the context of a single embodiment can also be implemented in multiple embodiments or in any suitable sub-combination, respectively. In addition, although the feature may be described above as acting in some combination and even initially claimed in this way, in some cases, one or more features from the claimed combination can be removed from the combination, and the claimed combination can be for a sub-combination or a variation of the sub-combination.

[0077] It should be understood that those skilled in the art may recognize that other embodiments with modifications, permutations, combinations, and additions may be implemented to perform the same, similar, substituted, or alternative functions of the disclosed subject matter, and are therefore considered to be within the scope of the present disclosure. Therefore, the disclosed subject matter should not be limited to any single embodiment described herein, but should be interpreted according to the breadth and scope of the following claims.

[0078] Similarly, although operations are depicted in a particular order in the accompanying drawings, this should not be understood as requiring that such operations be performed in the particular order shown or sequentially, or that all of the illustrated operations be performed to achieve the desired results, unless otherwise described. For the purposes of the depicted embodiments, any operational steps shown in dashed lines in one or more of the flow charts shown herein are optional.

[0079] The following exemplary embodiments are provided, the numbering of which should not be construed as designating a level of importance.

[0080] Embodiment 1 provides an electrochemical cell system configured to reduce the concentration of a target gas in a refrigerated environment, comprising: an electrochemical cell device, the electrochemical cell device comprising a shell having an air hole, a first electrode and a second electrode disposed in the shell, wherein the device is configured to receive the target gas through the air hole, at least partially electrochemically oxidize the target gas when in contact with a surface of the first electrode to form one or more reaction products, and spread at least a portion of the one or more reaction products through the air hole to reduce the concentration of the target gas; an air circulation device; and a flow hood, wherein the electrochemical cell device is connected to the air circulation device via the flow hood, and the flow hood defines a flow path for the target gas to flow across the air hole of the electrochemical cell device.

[0081] Embodiment 2 provides a system according to embodiment 1, wherein the flow hood is configured such that it generates turbulent flow of the target gas through the flow hood.

[0082] Embodiment 3 provides a system according to any one of embodiments 1 and 2, wherein the flow hood includes one or more protrusions in the flow path.

[0083] Embodiment 4 provides a system according to any one of Embodiments 1 to 3, wherein the electrochemical cell device further comprises a third electrode.

[0084] Embodiment 5 provides a system according to embodiment 4, wherein the electrochemical cell device further includes a fourth electrode.

[0085] Embodiment 6 provides a system according to embodiment 1, wherein the electrochemical cell device further comprises one or more electrolyte separators disposed between the first electrode and the second electrode.

[0086] Embodiment 7 provides a system according to any one of Embodiments 1 to 6, wherein the first electrode comprises a first gas permeable membrane and a first catalyst mixture, and the first electrode is positioned within the housing so that the target gas passes through the first gas permeable membrane before reaching the first catalyst mixture.

[0087] Embodiment 8 provides a system according to any one of embodiments 1 to 7, wherein the target gas comprises ethylene, hydrogen sulfide, or a combination thereof.

[0088] Embodiment 9 provides a system according to any one of embodiments 1 to 8, wherein at least one of the electrodes comprises gold or a gold alloy.

[0089] Embodiment 10 provides a system according to any one of embodiments 1 to 3, wherein the air circulation device is a fan.

[0090] Embodiment 11 provides a system according to any one of embodiments 1 to 3, wherein the air circulation device is a pump.

[0091] Embodiment 12 provides a system according to any one of Embodiments 1 to 11, further comprising an electronic circuit configured to measure the current generated by the electrochemical cell device.

[0092] Embodiment 13 provides a system according to embodiment 12, wherein the air circulation device is configured such that it is activated when the current generated by the electrochemical cell device meets a predetermined threshold.

[0093] Embodiment 14 provides a system according to any one of embodiments 1 to 13, wherein the electrochemical cell system further comprises a timer, and wherein the air circulation device is configured such that it is activated upon expiration of a defined time period measured by the timer.

[0094] Embodiment 15 provides a system according to embodiment 1, further comprising a high surface area carbon filter.

[0095] Many modifications and other embodiments of the invention set forth herein will occur to those skilled in the art to which these embodiments of the invention pertain, having the benefit of the teachings presented in the foregoing description and the associated drawings. It should be understood, therefore, that the embodiments of the invention are not limited to the specific embodiments disclosed, and modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

1. An electrochemical cell system configured to reduce the concentration of a target gas in a refrigerated environment, comprising: an electrochemical cell device, the electrochemical cell device comprising a housing having pores, a first electrode and a second electrode disposed within the housing, and one or more electrolyte separators disposed between the first electrode and the second electrode, wherein the electrochemical cell device is configured to receive the target gas through the pores, at least partially electrochemically oxidize the target gas when in contact with a surface of the first electrode to form one or more reaction products, and disperse at least a portion of the one or more reaction products through the pores to reduce a concentration of the target gas; Air circulation devices; and a flow hood, wherein the electrochemical cell device is coupled to the air circulation device via the flow hood, the flow hood defining a flow path for the target gas to flow across the air holes of the electrochemical cell device, One or more cross-barriers are disposed in the one or more electrolyte separators and are configured such that they form a path between the first electrode and the second electrode and also restrict any reaction products from the electrochemical oxidation of the target gas from reaching the second electrode. 2 . The electrochemical cell system of claim 1 , wherein the flow hood is configured such that it generates turbulent flow of the target gas through the flow hood. 3 . The electrochemical cell system of claim 1 , wherein the flow hood comprises one or more protrusions in the flow path.

4. The electrochemical cell system of claim 1, wherein the electrochemical cell device further comprises a third electrode.

5. The electrochemical cell system of claim 4, wherein the electrochemical cell device further comprises a fourth electrode.

6. The electrochemical cell system of claim 1, wherein the electrochemical cell device further comprises one or more electrolyte separators disposed between the first electrode and the second electrode.

7. The electrochemical cell system of claim 1, wherein the first electrode comprises a first gas permeable membrane and a first catalyst mixture, the first electrode being positioned within the housing such that the target gas passes through the first gas permeable membrane before reaching the first catalyst mixture.

8. The electrochemical cell system of claim 1, wherein the target gas comprises ethylene, hydrogen sulfide, or a combination thereof.

9. The electrochemical cell system of claim 1, wherein the air circulation device is a fan or a pump.

10. The electrochemical battery system of claim 1, further comprising an electronic circuit configured to measure a current generated by the electrochemical battery device, and the air circulation device is configured such that it is activated when the current generated by the electrochemical battery device meets a predetermined threshold.

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