Patent Publication Number: US-2019166886-A1

Title: Flow circuit for carbonated beverage machine

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application No. 62/065,966, filed Oct. 20, 2014, which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     The inventions described herein relate to dissolving gas in liquids, e.g., carbonation, for use in preparing a beverage. Systems for carbonating liquids and/or mixing liquids with a beverage medium to form a beverage are described in a wide variety of publications, including U.S. Pat. Nos. 4,025,655, 4,040,342; 4,636,337; 6,712,342 and 5,182,084; and PCT Publication WO 2008/124851. 
     SUMMARY OF INVENTION 
     Aspects of the invention relate to carbonating or otherwise dissolving a gas in a precursor liquid, such as water, to form a beverage. In some embodiments, a carbon dioxide or other gas source can be provided in a cartridge which is used to generate carbon dioxide or other gas that is dissolved into the precursor liquid. A beverage medium, such as a powdered drink mix or liquid syrup, may be provided in the same, or a separate cartridge as the gas source and mixed with the precursor liquid (either before or after carbonation) to form a beverage. The use of one or more cartridges for the gas source and/or beverage medium may make for an easy to use and mess-free system for making carbonated or other sparkling beverages, e.g., in the consumer&#39;s home. A beverage medium included in a cartridge may include any suitable beverage making materials (beverage medium), such as concentrated syrups, ground coffee or liquid coffee extract, tea leaves, dry herbal tea, powdered beverage concentrate, dried fruit extract or powder, natural and/or artificial flavors or colors, acids, aromas, viscosity modifiers, clouding agents, antioxidants, powdered or liquid concentrated bouillon or other soup, powdered or liquid medicinal materials (such as powdered vitamins, minerals, bioactive ingredients, drugs or other pharmaceuticals, nutriceuticals, etc.), powdered or liquid milk or other creamers, sweeteners, thickeners, and so on. (As used herein, “mixing” of a liquid with a beverage medium includes a variety of mechanisms, such as the dissolving of substances in the beverage medium in the liquid, the extraction of substances from the beverage medium, and/or the liquid otherwise receiving some material from the beverage medium or otherwise combining with the beverage medium.) (The term “carbonation” or “carbonated” is used herein to generically refer to beverages that have a dissolved gas, and thus refers to a sparkling beverage whether the dissolved gas is carbon dioxide, nitrogen, oxygen, air or other gas. Thus, aspects of the invention are not limited to forming beverages that have a dissolved carbon dioxide content, but rather may include any dissolved gas.) 
     In one aspect, a beverage making machine includes a precursor liquid supply to provide precursor liquid used to form a beverage, and a carbonation tank having an inlet coupled to receive precursor liquid delivered by the precursor liquid supply and an outlet at a bottom of the carbonation tank to deliver precursor liquid from the tank to a dispense line that leads to a dispensing station. A carbonating gas supply line may be fluidly coupled to the dispense line of the carbonation tank to deliver carbon dioxide gas to the outlet of the carbonation tank to carbonate the precursor liquid. In some cases, the gas supply line may include a gas delivery valve between a source of pressurized gas and the dispense line that is controllable to open and close the gas supply line, and the dispense line may include a dispense valve that is controllable to open and close the dispense line. 
     Certain advantages may be provided by delivering carbonating gas to the tank via the dispense line. For example, delivering carbonating gas at a relatively low point in the tank may help increase contact of the gas with the precursor liquid, thereby enhancing dissolution of the gas. In addition, or alternately, the flow of carbonating gas through at least a portion of the dispense line may help purge the dispense line of liquid (e.g., remaining from a prior dispensed beverage). Purging the dispense line back into the tank may help ensure that any purged liquid in the dispense line is suitably chilled and/or carbonated. That is, if chilled and carbonated liquid from a prior beverage sits in the dispense line for an extended period, the liquid may release the carbonating gas and/or warm to a temperature above that desired. The carbonating gas may drive the liquid in the dispense line back into the tank to be chilled and/or carbonated. 
     In one embodiment, the precursor liquid supply includes a pump arranged to deliver precursor liquid to the carbonation tank, and in some cases the same pump may be arranged to pump gas (such as air) to the tank to force precursor liquid from the carbonation tank and into the dispense line. Thus, a single pump can be used to deliver liquid to the carbonating tank, and cause liquid in the tank to be dispensed by forcing gas into the tank. Prior to dispensing a carbonated liquid, the tank may be coupled to a vent to release pressure in the tank, and then the vent may be closed and gas pumped into the tank to force carbonated precursor liquid from the carbonation tank and into the dispense line. 
     The carbonating gas supply line may be coupled to a source of pressurized carbon dioxide used to carbonate precursor liquid in the tank, e.g., the source of pressurized carbon dioxide may be a gas source in a cartridge that is activated to release carbon dioxide in the presence of a fluid. In some embodiments, the precursor liquid supply may be arranged to deliver precursor liquid to the gas source in the cartridge to cause the gas source to release carbon dioxide. 
     In some embodiments, a mixing chamber may be coupled to the dispense line to mix the carbonated precursor liquid with a beverage medium that may be provided from a cartridge. For example, a cartridge holder may be arranged to hold a cartridge having a container defining a sealed internal space with a first chamber and a second chamber that are isolated from each other. The first chamber may contain a carbon dioxide source in solid form, having adsorbed carbon dioxide, and arranged to emit the carbon dioxide gas for use in carbonating the precursor liquid to form a beverage. The second chamber may contain a beverage medium for use in mixing with the precursor liquid to form a beverage. The cartridge holder may be arranged to introduce pressurized gas into the second chamber to cause the beverage medium to exit the second chamber, e.g., to flow to the mixing chamber. 
     In some embodiments, the cartridge holder may be arranged to pierce the first chamber to form an opening through which an activating fluid is introduced into the first chamber to cause the carbon dioxide source to emit the carbon dioxide. A carbon dioxide activating fluid supply may be arranged to provide a fluid to the cartridge chamber for contact with the carbon dioxide source to cause the carbon dioxide source to emit carbon dioxide gas, e.g., water may be provided to activate the gas source. In some embodiments, the cartridge may include a lid at a top of the container, and the cartridge holder may be arranged to pierce the lid to form openings through which the activating fluid enters the first chamber and carbon dioxide exits the first chamber. The cartridge holder may also be arranged to pierce the second chamber to form an opening through which pressurized gas is introduced to force the beverage medium to exit the second chamber. 
     The carbonation tank may be arranged in different ways, and in one embodiment includes a cooling container tank around at least a portion of the carbonation tank arranged to hold ice to cool precursor liquid in the carbonation tank. An agitator may be arranged to move precursor liquid in the carbonation tank to aid in carbonation of the precursor liquid. 
     In another aspect, a method of making a beverage includes delivering precursor liquid to a carbonation tank having an outlet at a bottom of the carbonation tank coupled to a dispense line, and delivering carbon dioxide gas under pressure to the carbonation tank via the outlet. As noted above, delivering carbonating gas to a tank via a dispense line may aid in carbonation and/or purge at least a portion of the dispense line. Precursor liquid in the carbonation tank may be carbonated with the carbon dioxide gas, and the carbonated precursor liquid delivered from the carbonation tank to the dispense line via the outlet. 
     In another aspect, a beverage making machine includes a precursor liquid supply includes a pump arranged to deliver precursor liquid, and a tank having an inlet coupled to an outlet side of the pump to receive precursor liquid delivered by the pump. An outlet of the tank is arranged to deliver precursor liquid from the tank to a dispensing station, and a gas supply line may be fluidly coupled to an inlet side of the pump. The pump may be arranged to pump gas from the gas supply line to the tank to cause precursor liquid in the tank to be delivered to the dispensing station. That is, a single pump may be employed to deliver liquid to the tank as well as deliver gas to the tank to cause liquid in the tank to be dispensed. Such an arrangement may eliminate multiple components, including separate pumps for liquid and gas delivery. 
     In one embodiment, the gas supply line may be fluidly coupled to a vent, and the pump may be arranged to pump gas from the vent to the tank to substantially empty the tank of precursor liquid. For example, liquid in the tank may be driven to flow from the tank and into a dispense line. In another arrangement, the gas supply line may be fluidly coupled to a source of pressurized gas, such as a carbonating gas supply that provides pressurized carbon dioxide used to carbonate precursor liquid in the tank. In one embodiment, the source of pressurized carbon dioxide includes a cartridge containing a gas source that is activated to release carbon dioxide in the presence of liquid. In another embodiment, the gas supply line may be arranged to vent the tank to ambient pressure, and to provide gas to the inlet side of the pump for delivery to the tank to cause the precursor liquid to be moved to the dispensing station. 
     In another aspect, a method of making a beverage includes delivering precursor liquid to a tank to form a beverage by pumping the precursor liquid via a pump, conditioning the liquid in the tank, e.g., by cooling and/or carbonating, and pumping a gas into the tank via the pump to cause the precursor liquid to be moved from the tank to a dispensing station. In some embodiments, air at ambient pressure from a vent may be pumped to the tank using the pump, and may cause the tank to substantially empty of precursor liquid. In other embodiments, gas from a source of pressurized gas may be pumped into the tank. 
     In another aspect, a beverage making machine includes a precursor liquid supply with a pump arranged to deliver precursor liquid to form a beverage, and a tank having an inlet coupled to an outlet side of the pump to receive precursor liquid delivered by the pump. An outlet of the tank may be arranged to deliver precursor liquid from the tank to a dispensing station, and a source of pressurized gas may be fluidly couplable to an inlet side of the pump and to the tank. The pressurized gas from the source of pressurized gas may be used for dissolution in the precursor liquid in the tank, e.g., to carbonate the liquid. In one embodiment, a vent may be fluidly coupled to the inlet side of the pump, and the pump may be arranged to pump air from the vent into the tank to move precursor liquid from the tank to the dispensing station. One or more valves may be arranged to selectively couple the vent or the source of pressurized gas to the inlet side of the pump so the pump may deliver either to the tank. The source of pressurized gas may include a source of pressurized carbon dioxide used to carbonate precursor liquid in the tank, e.g., may include a cartridge containing a gas source that is activated to release carbon dioxide in the presence of a liquid. In some embodiments, a water trap may be connected between the source of pressurized gas and the inlet side of the pump, e.g., so the water trap can trap water droplets included with the gas such that the water droplets are not delivered to the inlet side of the pump. A drain valve may be positioned between the water trap and the vent, e.g., so liquid in the trap can be drained. 
     In another aspect, a method of making a beverage includes delivering precursor liquid to a tank to form a beverage by pumping the precursor liquid via a pump, delivering a fluid via operation of the pump to a gas source to cause the gas source to emit a pressurized gas to be dissolved in the precursor liquid in the tank, and fluidly coupling the pressurized gas from the gas source to an inlet side of the pump while the pump is operated to deliver the fluid to the gas source. By coupling the pressurized gas from the gas source to the inlet side of the pump, a pressure drop across the pump may be reduced, allowing the pump to operate with lower power requirements. In some embodiments, a gas may also be pumped into the tank by the pump to cause the precursor liquid to be moved from the tank to a dispensing station. For example, air at ambient pressure from a vent may be pumped to the tank using the pump. 
     In another aspect, a beverage making machine includes a precursor liquid supply to provide precursor liquid used to form a beverage, and a tank having an inlet coupled to the precursor liquid and an outlet to deliver precursor liquid from the tank to a dispensing station. A source of pressurized gas may be fluidly couplable to the tank to provide pressurized gas for dissolution in the precursor liquid in the tank, and a water trap may be fluidly coupled between the source of pressurized gas and the tank to trap liquid droplets in fluid flow from the source of pressurized gas to the tank. The water trap may be effective when moisture is included with gas provided from a gas source, such as when the gas source is activated by a liquid. As noted above, a cartridge may include a zeolite or other molecular sieve gas source that releases adsorbed gas in the presence of water. If liquid water is included in produced gas, the water trap may help remove some moisture from the gas. 
     In some embodiments, a vent may be fluidly coupled to an inlet side of the water trap, e.g., to allow liquid in the trap to drain to a drain line or to allow the pump to intake air that is pumped to the tank. In one embodiment, one or more valves may selectively couple the vent or the source of pressurized gas to the tank. In one embodiment, the precursor liquid supply may include a pump with an inlet side, and the water trap may be connected to the inlet side of the pump. 
     In another aspect, a method of making a beverage includes delivering precursor liquid to a tank, delivering a pressurized gas to a water trap to remove any water droplets in the pressurized gas, and delivering the pressurized gas from the water trap to the tank to dissolve the pressurized gas in the precursor liquid. In one embodiment, the pressurized gas is carbon dioxide, and a cartridge is provided with a gas source arranged to release carbon dioxide in the presence of a liquid. For example, precursor liquid may be delivered to the gas source to cause the gas source to release the carbon dioxide. 
     In one aspect, a beverage making system includes a beverage precursor liquid supply arranged to provide a precursor liquid. The precursor liquid supply may include a reservoir, a pump, one or more conduits, one or more valves, one or more sensors (e.g., to detect a water level in the reservoir), and/or any other suitable components to provide water or other precursor liquid in a way suitable to form a beverage. The system may also include a single cartridge having first and/or second compartments or chambers. The first cartridge chamber may contain a gas source arranged to emit gas for use in dissolving into the precursor liquid, e.g., for carbonating the precursor liquid, and the second cartridge chamber may contain a beverage medium arranged to be mixed with a liquid precursor to form a beverage. The system may include a cartridge interface, such as a chamber that receives and at least partially encloses the cartridge, a connection port arranged to fluidly couple with the cartridge, or other arrangement. A gas dissolution device may be arranged to dissolve gas that is emitted from the first cartridge chamber into the precursor liquid, and may include, for example, a membrane contactor, a tank suitable to hold a liquid under pressure to help dissolve gas in the liquid, a sparger, a sprinkler arranged to introduce water to a pressurized gas environment, or other arrangement. The system may be arranged to mix precursor liquid with the beverage medium, whether before or after gas is dissolved in the liquid, to form a beverage. The beverage medium may be mixed with the liquid in the cartridge, in another portion of the system such as a mixing chamber into which beverage medium from the cartridge is introduced along with precursor liquid, in a user&#39;s cup, or elsewhere. 
     In some embodiments, the first and second cartridge chambers may each have a volume that is less than a volume of carbonated beverage to be formed using the cartridge portions. This can provide a significant advantage by allowing a user to form a relatively large volume beverage using a relative small volume cartridge or cartridges. For example, the system may be arranged to use the first and second cartridge portions over a period of time less than about 120 seconds to form a carbonated liquid having a volume of between 100-1000 ml and a carbonation level of about 1 to 5 volumes. Carbonation may occur at pressures between 20-80 psi, or more. The cartridge portions in this embodiment may have a volume of about 40-80 ml or less, reducing an amount of waste and/or adding to convenience of the system. 
     In one embodiment, a carbonated and flavored beverage may be made over a period of time less than about 120 seconds (e.g., about 60 seconds) and using a gas pressure of 20-80 psi (e.g., above ambient) to form a carbonated liquid having a volume of between 100-1000 ml (e.g., about 500 ml) and a carbonation level of about 2 to 4 volumes (or less or more, such as 1 to 5 volumes). Thus, systems and methods according to this aspect may produce a relatively highly carbonated beverage in a relatively short period of time, and without requiring high pressures. 
     These and other aspects of the invention will be apparent from the following description and claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Aspects of the invention are described with reference to the following drawings in which like numerals reference like elements, and wherein: 
         FIG. 1  shows a perspective view of an illustrative embodiment of a beverage making system having a removable reservoir; 
         FIG. 2  shows a top view of the beverage making system of  FIG. 1 ; 
         FIG. 3  shows a left side view of the beverage making system of  FIG. 1 ; 
         FIG. 4  shows a left side view of the beverage making system of  FIG. 1  and a cartridge is located in a cartridge holder; 
         FIG. 5  shows an exploded view of the beverage making system of  FIG. 1 ; 
         FIG. 6  shows a schematic diagram of an illustrative flow circuit in a beverage making system; 
         FIG. 7  shows a schematic diagram of another illustrative flow circuit in a beverage making system; 
         FIG. 8  shows a schematic diagram of yet another illustrative flow circuit in a beverage making system; 
         FIG. 9  shows a cross sectional view of a carbonation tank and cooling container in an illustrative embodiment; 
         FIG. 10  shows an exploded view of a carbonation tank and cooling system in an illustrative embodiment; 
         FIG. 11  shows a top view of an assembled carbonation tank and cooling container in an illustrative embodiment; 
         FIG. 12  shows a perspective view of the carbonation tank of  FIG. 11 ; 
         FIG. 13  shows a schematic view of a cooling system in an illustrative embodiment; 
         FIG. 14  shows a schematic view of another cooling system in an illustrative embodiment; 
         FIG. 15  shows a schematic view of yet another cooling system in an illustrative embodiment; 
         FIG. 16  shows a perspective view of a cartridge which can be used with the  FIGS. 1-4  embodiment; 
         FIG. 17  shows a cross sectional view of the  FIG. 16  cartridge; 
         FIG. 18  shows a perspective view of another illustrative cartridge; 
         FIG. 19  shows a cross sectional view of a cartridge holder useable with the  FIGS. 1-4  embodiment with a cartridge receiver in an open position; 
         FIG. 20  shows a cross sectional view of the  FIG. 19  cartridge holder with the cartridge receiver in a closed position; 
         FIG. 21  shows a top view of the  FIG. 19  cartridge holder; 
         FIG. 22  shows a cross sectional view of an alternative cartridge holder including a mixing chamber; 
         FIG. 23  perspective view of the mixing chamber of  FIG. 22 ; and 
         FIG. 24  shows a cross sectional view of the  FIG. 22  mixing chamber. 
     
    
    
     DETAILED DESCRIPTION 
     It should be understood that aspects of the invention are described herein with reference to the figures, which show illustrative embodiments. The illustrative embodiments described herein are not necessarily intended to show all embodiments in accordance with the invention, but rather are used to describe a few illustrative embodiments. Thus, aspects of the invention are not intended to be construed narrowly in view of the illustrative embodiments. In addition, it should be understood that aspects of the invention may be used alone or in any suitable combination with other aspects of the invention. 
     In accordance with one aspect of the invention, a fluid (such as water, water vapor, or other) may be provided to a carbon dioxide or other gas source in a cartridge so as to cause the gas source to emit gas that is used to carbonate or otherwise for dissolution in a liquid. In one embodiment, a beverage making machine may include a gas activating fluid supply arranged to provide fluid to a cartridge chamber for contact with the gas source so as to cause the gas source to emit gas. In other arrangements, the gas source may be caused to release gas in other ways, such as by heating, exposing the source to microwaves or other electromagnetic radiation, etc. A gas supply of the machine may be arranged to conduct gas emitted by the gas source, under pressure greater than the ambient pressure, to a precursor liquid to carbonate the precursor liquid. In some embodiments, the gas source may be in solid form, such as a zeolite, activated carbon or other molecular sieve that is charged with carbon dioxide or other gas, and the use of a cartridge may not only isolate the gas source from activating agents (such as water vapor in the case of a charged zeolite), but also potentially eliminate the need for a user to touch or otherwise directly handle the carbon dioxide source. 
     Having a gas activating fluid supply may enable the use of another aspect of the invention, i.e., a volume or other measure of the fluid provided to the cartridge may be controlled to control the rate or amount of gas that produced by the gas source. This feature can make the use of some gas sources, such as a charged zeolite material, possible without requiring gas storage or high pressure components, although high pressure gas cylinders can be used as a gas source with some embodiments. For example, zeolites charged with carbon dioxide tend to release carbon dioxide very rapidly and in relatively large quantities (e.g., a 30 gram mass of charged zeolite can easily produce 1-2 liters of carbon dioxide gas at atmospheric pressure in a few seconds in the presence of less than 30-50 ml of water). This rapid release can in some circumstances make the use of zeolites impractical for producing relatively highly carbonated liquids, such as a carbonated water that is carbonated to a level of 2 volumes or more. (A carbonation “volume” refers to the number of volume measures of carbon dioxide gas that is dissolved in a given volume measure of liquid. For example, a 1 liter amount of “2 volume” carbonated water includes a 1 liter volume of water that has 2 liters of carbon dioxide gas dissolved in it. Similarly, a 1 liter amount of “4 volume” carbonated water includes a 1 liter volume of water that has 4 liters of carbon dioxide dissolved in it. The gas volume measure is the gas volume that could be released from the carbonated liquid at atmospheric or ambient pressure and room temperature.) That is, dissolution of carbon dioxide or other gases in liquids typically takes a certain amount of time, and the rate of dissolution can only be increased a limited amount under less than extreme conditions, such as pressures within about 150 psi of ambient and temperatures within about +/−40 to 50 degrees C. of room temperature. By controlling the rate of carbon dioxide (or other gas) production for a carbon dioxide (or other gas) source, the total time over which the carbon dioxide (or other gas) source emits carbon dioxide (or other gas) can be extended, allowing time for the carbon dioxide (gas) to be dissolved without requiring relatively high pressures. For example, when employing one illustrative embodiment incorporating one or more aspects of the invention, the inventors have produced liquids having at least up to about 3.5 volume carbonation levels in less than 60 seconds, at pressures under about 80 psi, and at temperatures around 0 degrees Celsius. Of course, as discussed above and elsewhere herein, aspects of the invention are not limited to use with carbon dioxide, and instead any suitable gas may be dissolved in a liquid in accordance with all aspects of this disclosure. 
     In another aspect of the invention, a portion of a precursor liquid that is used to form a beverage may be used to activate the gas source. This feature may help simplify operation of a beverage making machine, e.g., by eliminating the need for special activation substances. As a result, a beverage making machine, or a method of forming a sparkling beverage, may be made less expensively and/or without special purpose ingredients. For example, in the case of a machine making carbonated water, all that is needed to activate the carbon dioxide source may be a portion of the water used to form the beverage. It should be understood, however, that other aspects of the invention need not require the use of a portion of precursor liquid to activate a carbon dioxide source, and instead may use any suitable activating agent, such as a citric acid in aqueous form that is added to a bicarbonate material, heat, microwave or other electromagnetic radiation used to activate a zeolite source, and others. For example, the cartridge that includes the carbon dioxide source may include (as part of the source), an activating agent whose addition to another component of the carbon dioxide source is controlled to control carbon dioxide production. 
       FIGS. 1-4  show an illustrative embodiment of a beverage making system  1  that incorporates one or more aspects of the invention. In this embodiment, components of the beverage making system  1  are located in or on a housing  21  which includes a drip tray  23  to support a user&#39;s cup or other container  8  and a reservoir  11 . In this case, the reservoir  11  is optionally removable from the housing  21  and contains beverage precursor liquid, such as water, that is used to form a beverage dispensed at a dispensing station  29  into the user&#39;s container  8 . The reservoir  11  includes a removable lid  11   a  that can be removed to provide precursor liquid  2  into the reservoir  11 , but such a lid  11   a  is not required. Moreover, the reservoir  11  need not be removable and/or may be replaced by a plumbed connection to a mains water source. The beverage precursor liquid  2  can be any suitable liquid, including water (e.g., flavored or otherwise treated water, such as sweetened, filtered, deionized, softened, carbonated, etc.), or any other suitable liquid used to form a beverage, such as milk, juice, coffee, tea, etc. (whether heated or cooled relative to room temperature or not). The reservoir  11  is part of a beverage precursor supply which provides the precursor liquid  2  for conditioning of some kind, e.g., carbonation, filtering, chilling, mixing with a beverage medium, etc., and subsequent dispensing as a beverage. 
     As can be seen in  FIG. 4 , a cartridge  4  containing a gas source and/or a beverage medium may be associated with a cartridge holder  3  of the system  1 . The gas source may emit carbon dioxide or other gas which is used by the system  1  to carbonate the precursor liquid, and a beverage medium, such as a flavoring agent, may be mixed with precursor liquid. In this embodiment, the cartridge  4  may be associated with the cartridge holder  3  by pulling a sliding drawer  31  forwardly to expose a cartridge receiver or receiving area of the drawer  31 . The cartridge  4 , which in this case includes an upper compartment or chamber  41  containing a gas source and a lower compartment or chamber  42  containing a beverage medium, may be placed in the cartridge receiving area of the drawer  31  and the drawer  31  closed by sliding to the left in  FIG. 4 . Thereafter, a user may interact with an interface  52 , such as a touch screen, button or other device by which the user can cause the system  1  to make a beverage. In response, the cartridge  4  may be clamped at a rim or band  44  located between the upper and lower compartments  41 ,  42  by the cartridge holder  3  and the compartments  41 ,  42  accessed to form the beverage. As is discussed in more detail below, aspects of the invention relate to a cartridge holder&#39;s ability to hold the upper and lower compartments  41 ,  42  of the cartridge  4  in spaces having different pressures (e.g., the upper compartment  41  may be held in a more highly pressurized space to receive carbonating gas than the lower compartment  42 ) and/or the holder&#39;s ability to pierce an inlet of the lower compartment  42  at an underside of the rim or band  44  to access the beverage medium (e.g., by injecting pressurized air or other gas into the lower compartment  42 , thereby forcing the beverage medium to exit the cartridge and be dispensed at the dispense station  29 ). Since the cartridge  4  may be replaceable, a user may exchange the cartridge  4  to make different beverages, such as carbonated water only, a carbonated and flavored beverage, a still and flavored beverage, etc. 
       FIG. 5  shows an exploded view of the  FIG. 1  embodiment including components that are located in the housing  21 . In this embodiment, the housing  21  includes a front panel  21   a , a back panel  21   b  and a base  21   c  that cooperate to house and/or support components of the system. Precursor liquid in the removable reservoir  11  is moved by a pump  13  via one or more control valves  51  to a carbonation tank  6  (supported on a support  61  over the pump  13 ) where the precursor liquid  2  is chilled by a cooling system  7  and carbonated. Thereafter, the precursor liquid is moved from the tank  6  to the dispense station  29  where the carbonated liquid may be mixed with a beverage medium in a cartridge  4  and dispensed. As mentioned above, beverage medium in the cartridge may be moved out of the cartridge by introducing pressurized gas into the cartridge  4 , e.g., by an air pump  43  pumping air into the cartridge  4  and forcing the beverage medium to exit via an outlet of the cartridge. Control of the system may be performed by control circuitry  5 , which may include a programmed general purpose computer and/or other data processing device along with suitable software or other operating instructions, one or more memories (including non-transient storage media that may store software and/or other operating instructions), a power supply  53  for the control circuitry  5  and/or other system components, temperature and liquid level sensors, pressure sensors, RFID interrogation devices or other machine readable indicia readers (such as those used to read and recognize alphanumeric text, barcodes, security inks, etc.), input/output interfaces (e.g., such as the user interface  52  to display information to a user and/or receive input from a user), communication buses or other links, a display, switches, relays, triacs, motors, mechanical linkages and/or actuators, or other components necessary to perform desired input/output or other functions. 
     In accordance with an aspect of the invention, the cooling system  7  used to chill precursor liquid in the carbonation tank  6  may include one or more thermoelectric devices  75  thermally coupled to the carbonation tank  6 , one or more heat pipes  76  having an evaporator section coupled to the thermoelectric devices  75 , and one or more heat sinks  77  thermally coupled to the condenser section of the heat pipes  76 . A cooling air flow may be moved through a duct  79  and across the heat sinks by a fan (not shown), another air mover, and/or in other ways, such as by convection. The use of a thermoelectric device/heat pipe/heat sink arrangement is not required for all embodiments, however, and other embodiments may include a conventional refrigeration system or other cooling system (such as that found in refrigerators, air conditioning units, or other devices used to remove heat from a material) to cool the liquid in the carbonation tank  6  or elsewhere in the system. In some arrangements, cooling the precursor liquid before entering or while in the carbonation tank  6  may help the carbonation process, e.g., because cooler liquids tend to dissolve carbon dioxide or other gas more rapidly and/or are capable of dissolving larger amounts of gas. However, carbonated liquid could be chilled after flowing from the carbonation tank, e.g., using a flow through device. 
     In accordance with an aspect of the invention, an outlet of the duct for the cooling system may be positioned adjacent an inlet opening for providing precursor liquid to the system. In some embodiments, the duct may be arranged such that any precursor liquid that is unintentionally provided into the duct outlet may be routed by the duct and/or portions of the housing to a bottom of the housing, e.g., exiting via holes at a bottom of the housing. This may help prevent damage to electrical components because such components may be located outside of the duct and/or otherwise protected from contact with the precursor liquid in the duct. For example, as can be seen in  FIG. 2 , a duct outlet  79   a  may be positioned at a top of the housing  21  adjacent the reservoir lid  11   a , which can be removed to expose an inlet opening  11   b  through which water may be provided into the reservoir  11 . In the process of pouring water into the reservoir  11 , it may be possible to spill some water into the duct outlet  79   a . However, in this embodiment, any liquid spilled into the duct outlet  79   a  may be routed by the duct  79  and/or portions of the housing  21  to a bottom of the housing  21 , e.g., to the base  21   c . In some cases, the liquid may flow into the drip tray  23  and/or may exit from the base  21   c  through holes in the base  21   c . The duct  79 , which may extend from the outlet  79   a  to an inlet (not shown) near a bottom of the housing  21 , may be isolated from all or most of any electrical components of the system  1  such that liquid entering the outlet  79   a  may flow downwardly to the bottom of the housing  21  without contact with electrical components. In this sense, the duct  79  may be isolated from electrical components of the system  1  such that liquid in the duct  79  does not contact the electrical components. This arrangement may help prevent damage to the system  1  if liquid accidentally enters the duct outlet  79   a.    
     A beverage making system  1  may employ different liquid and gas flow path arrangements in accordance with aspects of the invention.  FIG. 6  shows one such arrangement in an illustrative embodiment. In this embodiment, precursor liquid  2  provided by a precursor liquid supply  10  originates in the reservoir  11 , which may be removable from the system  1 , e.g., to allow for easier filling, or may be fixed in place. Although in this embodiment a user initially provides the beverage precursor liquid  2  in the reservoir  11 , the precursor supply  10  may include other components to provide liquid  2  to the reservoir  11 , such as a plumbed water line, controllable valve, and liquid level sensor to automatically fill the reservoir  11  to a desired level, a second water reservoir or other tank that is fluidly connected to the reservoir  11 , and other arrangements. Liquid  2  is delivered by a pump  13  to the carbonation tank  6  via a three-way valve  51   c . In this instance, the pump  13  is a solenoid pump, but other pump types are possible. The carbonation tank  6  may be suitably filled with liquid  2  using any suitable control method, such as by sensing a level in the tank  6  using a conductive probe, pressure sensor, optical sensor or other sensor. A tank vent valve  51   b  may be opened during filling to allow the pressure in the tank  6  to vent, or may remain closed during filling, e.g., to allow a pressure build up in the tank  6 . Though not shown in  FIG. 6 , the control circuit  5  may control operation of the valves  51 , e.g., the valves  51  may include electromechanical or other actuators, as well as include sensors to detect various characteristics, such as temperature in the tank  6 , pressure in the tank  6 , a flow rate of gas or liquid in any of the system flow lines, etc. 
     To form a beverage, a user may associate a cartridge  4  with the system  1 , e.g., by loading the cartridge  4  into a cartridge holder  3  in a way like that discussed with respect to  FIG. 4 . Of course, a cartridge may be associated with the system  1  in other ways, such as by screwing a portion of the cartridge into engagement with the system  1 , etc. With the cartridge  4  associated with the system  1 , the control circuit  5  may then activate the system  1  to deliver liquid to the cartridge  4 , e.g., to cause carbon dioxide to be generated. (Though this embodiment uses a cartridge with a gas source activated by a fluid, other arrangements are possible, including the use of a pressurized gas cylinder as a gas source.) The control circuit  5  may start operation of the system  1  in an automated way, e.g., based on detecting the presence of a cartridge  4  in the holder  3 , detecting liquid  2  in the carbonation tank  6  and closure of the holder  3 , and/or other characteristics of the system  1 . Alternately, the control circuit  5  may start system operation in response to a user pressing a start button or otherwise providing input (e.g., by voice activation) to start beverage preparation. 
     To initiate carbonation, the vent valve  51   b  may be closed and the three-way valve  51   c  controlled to allow the pump  13  to pump liquid into the upper compartment  41  of a cartridge  4  that contains a gas source. That is, the system  1  may include a carbon dioxide activating fluid supply  20  that provides a fluid to a cartridge  4  so as to activate a carbon dioxide source in the upper compartment  41  to release carbon dioxide gas. In this embodiment, the carbon dioxide source includes a charged adsorbent or molecular sieve, e.g., a zeolite material that has adsorbed some amount of carbon dioxide gas that is released in the presence of water, whether in vapor or liquid form. Of course, other carbon dioxide source materials may be used, such as charcoal or other molecular sieve materials, carbon nanotubes, metal organic frameworks, covalent organic frameworks, porous polymers, or source materials that generate carbon dioxide by chemical means, such as sodium bicarbonate and citric acid (with the addition of water if the bicarbonate and acid are initially in dry form), or others. In addition, aspects of the invention are not necessarily limited to use with carbon dioxide gas, but may be used with any suitable gas, such as nitrogen, which is dissolved in some beers or other beverages, oxygen, air, and others. Thus, reference to “carbonation”, “carbon dioxide source” “carbon dioxide activating fluid supply”, etc., should not be interpreted as limiting aspects of the invention and/or any embodiments to use with carbon dioxide only. Instead, aspects of the invention may be used with any suitable gas. 
     In one embodiment, the charged adsorbent is a zeolite such as analcime, chabazite, clinoptilolite, heulandite, natrolite, phillipsite, or stilbite. The zeolite may be naturally occurring or synthetic, and may be capable of holding up to about 18% carbon dioxide by weight or more. The zeolite material may be arranged in any suitable form, such as a solid block (e.g., in disc form), particles of spherical, cubic, irregular or other suitable shape, and others. An arrangement that allows the zeolite to flow or be flowable, e.g., spherical particles, may be useful for packaging the zeolite in individual cartridges. Such an arrangement may allow the zeolite to flow from a hopper into a cartridge container, for example, simplifying the manufacturing process. The surface area of the zeolite particles may also be arranged to help control the rate at which the zeolite releases carbon dioxide gas, since higher surface area measures typically increase the gas production rate. Generally, zeolite materials will release adsorbed carbon dioxide in the presence of water in liquid or vapor form, allowing the zeolite to be activated to release carbon dioxide gas by the addition of liquid water to the zeolite. 
     The carbon dioxide activating fluid supply  20  in this embodiment includes a conduit that is fluidly coupled to the pump  13  and the valve  51   c  that can be controlled to open/close or otherwise control the flow of precursor liquid  2  into the cartridge  4 . That is, and in accordance with an aspect of the invention, a single pump may be arranged to both deliver precursor liquid to the carbonation tank and deliver activating fluid to a gas source. Other arrangements or additions are possible for the carbon dioxide activating fluid supply  20 , such as a dedicated liquid supply for the cartridge  4  that is separate from the precursor liquid supply, a pressure-reducing element in the conduit, a flow-restrictor in the conduit, a flow meter to indicate an amount and/or flow rate of fluid into the cartridge  4 , a syringe, piston pump or other positive displacement device that can meter desired amounts of liquid (whether water, citric acid or other material) to the cartridge  4 , and others. In another embodiment, the activating fluid supply  20  may include a gravity fed liquid supply that has a controllable delivery rate, e.g., like the drip-type liquid supply systems used with intravenous lines for providing liquids to hospital patients, or may spray atomized water or other liquid to provide a water vapor or other gas phase activating fluid to the cartridge  4 . 
     A carbon dioxide gas supply  30  may be arranged to provide carbon dioxide gas from the cartridge  4  to an area where the gas is used to carbonate the liquid  2 , in this case, the carbonation tank  6 . The gas supply  30  may be arranged in any suitable way, and in this illustrative embodiment includes a conduit that is fluidly connected between the cartridge  4  and a carbonated liquid outlet of the carbonation tank  6 . A gas control valve  51   d  is controllable by the control circuit  5  to open and close the flow path through the gas supply conduit. (Note that in some embodiments, the valve  51   d  may be a check valve that is not controllable by the control circuit  5 .) In accordance with an aspect of the invention, the carbonation gas is delivered via a carbonating gas supply line that is fluidly coupled to the dispense line of the carbonation tank so as to deliver carbon dioxide gas to the outlet of the carbonation tank to carbonate the precursor liquid. This arrangement may provide advantages, such as introducing the carbonating gas at a relatively low point in the tank, which may help increase contact of the gas with the precursor liquid, thereby enhancing dissolution of the gas. In addition, the flow of carbonating gas through at least a portion of the dispense line  38  may help purge the dispense line  38  of liquid, helping to re-carbonate the liquid, if necessary. The gas conduit may be connected to the dispense line  38  close to the dispense valve  51   e  so as to purge as much liquid from the dispense line  38  as possible. 
     The gas supply  30  may include other components than a conduit and valve, such as pressure regulators, safety valves, additional control valves, a compressor or pump (e.g., to increase a pressure of the gas), an accumulator (e.g., to help maintain a relatively constant gas pressure and/or store gas), and so on. (The use of an accumulator or similar gas storage device may obviate the need to control the rate of gas output by a cartridge. Instead, the gas source may be permitted to emit gas in an uncontrolled manner, with the emitted gas being stored in an accumulator for later delivery and use in producing a sparkling beverage. Gas released from the accumulator could be released in a controlled manner, e.g., at a controlled pressure and/or flow rate.) Also, carbonation of the precursor liquid  2  may occur via one or more mechanisms or processes, and thus is not limited to one particular process. For example, while delivery of carbon dioxide gas to the outlet of the carbonation tank  6  may function to help dissolve carbon dioxide in the liquid  2 , other system components may further aid in the carbonation process. In some embodiments, a sparger may be used to introduce gas into the carbonation tank, precursor liquid may be circulated in the tank, and/or other techniques may be used to alter a rate at which carbonating gas is dissolved. 
     Before, during and/or after carbonation of the liquid  2  in the carbonation tank  6 , the cooling system  7  may chill the liquid  2 . As noted above, the cooling system  7  may operate in any suitable way, e.g., may include ice, refrigeration coils or other cooling elements in thermal contact with the carbonation tank  6 . In addition, the carbonation tank  6  may include a mixer or other agitator to move the liquid in the tank  6  to enhance gas dissolution and/or cooling. Operation in forming a beverage may continue for a preset amount of time, or based on other conditions, such as a detected level of carbonation, a drop in gas production by the cartridge  4 , or other parameters. During operation, the amount of liquid provided to the cartridge  4  may be controlled to control gas output by the cartridge  4 . Control of the liquid provided to the cartridge  4  may be made based on a timing sequence (e.g., the valve  51   c  may be opened for a period of time, followed by valve closure for a period, and so on), based on detected pressure (e.g., liquid supply may be stopped when the pressure in the tank  6  exceeds a threshold, and resume when the pressure falls below the threshold or another value), based on a volume of activating liquid delivered to the holder  3  (e.g., a specific volume of liquid may be delivered to the cartridge  4  in one or more discrete volumes), or other arrangements. 
     With the precursor liquid  2  in the carbonation tank  6  ready for dispensing, the vent valve  51   b  may be opened to reduce the pressure in the carbonation tank  6  to an ambient pressure. As is known in the art, depressurizing the carbonation tank prior to dispensing may aid in maintaining a desired carbonation level of the liquid during dispensing. With the tank  6  vented, the vent valve  51   b  may be closed and a pump vent valve  51   a  may be opened. The pump  13  may then be operated to draw air or other gas into the inlet side of the pump  13  and pump the gas into the carbonation tank  6  so as to force the precursor liquid  2  in the tank  6  to flow into the dispense line  38 . That is, the arrangement of  FIG. 6  incorporates another aspect of the invention in that a single pump may be used to both deliver precursor liquid to a carbonation tank or other carbonation location as well as deliver pressurized gas (air) to the carbonation tank to dispense carbonated liquid from the tank. This feature, optionally combined with the feature of using the same pump to deliver activating fluid to a gas source, may make for a simplified system with fewer components. While the pump  13  delivers air to the carbonation tank, the dispense valve  51   e  is opened and the gas valve  51   d  is closed during liquid dispensing. The dispensed liquid may enter a mixing chamber  9  at which the carbonated liquid and beverage medium provided from the lower compartment  42  of the cartridge  4  are combined. The beverage medium may be moved out of the cartridge  4  and to the mixing chamber  9  by introducing pressurized gas into the lower compartment  42 , e.g., by way of an air pump  43 . Other arrangements are possible, however, such as routing gas from the upper compartment  41  under pressure to the lower compartment  42 . 
     The control circuit  5  may use one or more sensors to control a carbonation level of the precursor liquid, a temperature to which the liquid is chilled (if at all), a time at which and during which beverage medium is delivered to the mixing chamber  9 , a rate at which carbonating gas is produced and delivered to the tank  6 , and/or other aspects of the beverage making process. For example, a temperature sensor may detect the temperature of the precursor liquid in the carbonation tank  6 . This information may be used to control system operation, e.g., warmer precursor liquid temperatures may cause the control circuit  5  to increase an amount of time allowed for carbon dioxide gas to be dissolved in the precursor liquid  2 . In other arrangements, the temperature of the precursor liquid  2  may be used to determine whether the system  1  will be operated to carbonate the liquid  2  or not. For example, in some arrangements, the user may be required to add suitably cold liquid  2  (and/or ice) to the reservoir  11  before the system  1  will operate. (As discussed above, relatively warm precursor liquid  2  temperatures may cause the liquid to be insufficiently carbonated in some conditions.) In another embodiment, a pressure sensor may be used to detect a pressure in the carbonation tank  6 . This information may be used to determine whether the carbonation tank  6  is properly or improperly filled, if a pressure leak is present, if carbonation is complete and/or to determine whether sufficient carbon dioxide gas is being produced by the cartridge  4 . For example, low detected pressure may indicate that more carbon dioxide needs to be generated, and thus cause the control circuit  5  to allow more liquid to be delivered by the activating fluid supply  20  to the cartridge  4 . Likewise, high pressures may cause the flow of liquid from the activating fluid supply  20  to be slowed or stopped. Thus, the control circuit  5  can control the gas pressure in the carbonation tank  6  and/or other areas of the system  1  by controlling an amount of liquid delivered to the cartridge  4 . Alternately, low pressure may indicate that there is a leak in the system and cause the system to indicate an error is present. In some embodiments, measured pressure may indicate that carbonation is complete. For example, pressure in the tank  6  may initially be detected to be at a high level, e.g. around 70-80 psi, and later be detected to be at a low level, e.g., around 40 psi due to gas being dissolved in the liquid. The low pressure detection may indicate that carbonation is complete. A sensor could also detect the presence of a cartridge  4  in the cartridge holder  3 , e.g., via RFID tag, optical recognition, physical sensing, etc. If no cartridge  4  is detected, or if the control circuit  5  detects that the cartridge  4  is spent, the control circuit  5  may prompt the user to insert a new or different cartridge  4 . For example, in some embodiments, a single cartridge  4  may be used to carbonate multiple volumes of precursor liquid  2 . The control circuit  5  may keep track of the number of times that the cartridge  4  has been used, and once a limit has been reached (e.g.,  10  drinks), prompt the user to replace the cartridge. Other parameters may be detected by a sensor, such as a carbonation level of the precursor liquid  2  (which may be used to control the carbonation process), the presence of a suitable vessel to receive a beverage discharged from the system  1  (e.g., to prevent beverage from being spilled), the presence of water or other precursor liquid  2  in the carbonation tank  6  or elsewhere in the precursor supply  10 , a flow rate of liquid in the pump  13  or associated conduit, the presence of a headspace in the carbonation tank  6  (e.g., if no headspace is desired, a valve may be activated to discharge the headspace gas, or if only carbon dioxide is desired to be in the headspace, a snifting valve may be activated to discharge air in the headspace and replace the air with carbon dioxide), and so on. 
     The control circuit  5  may also be arranged to allow a user to define a level of carbonation (i.e., amount of dissolved gas in the beverage, whether carbon dioxide or other). For example, the control circuit  5  may include a touch screen display or other user interface  52  that allows the user to define a desired carbonation level, such as by allowing the user to select a carbonation volume level of 1, 2, 3, 4 or 5, or selecting one of a low, medium or high carbonation level. Cartridges used by the system  1  may include sufficient gas source material to make the highest level of carbonation selectable, but the control circuit  5  may control the system to dissolve an amount of gas in the beverage that is consistent with the selected level. For example, while all cartridges may be arranged for use in creating a “high” carbonation beverage, the control circuit  5  may operate the system  1  to use less of the available gas (or cause the gas source to emit less gas than possible) in carbonating the beverage. Carbonation levels may be controlled based on a detected carbonation level by a sensor, a detected pressure in the carbonation tank  6  or elsewhere, an amount of gas output by the cartridge  4 , or other features. 
     In another embodiment, the cartridge  4  may include indicia readably by the controller, e.g., an RFID tag, barcode, alphanumeric string, etc., that indicates a carbonation level to be used for the beverage. After determining the carbonation level from the cartridge  4 , the control circuit  5  may control the system  1  accordingly. Thus, a user need not select the carbonation level by interacting with the system  1 , but rather a carbonation level may be automatically adjusted based on the beverage selected. In yet another embodiment, a user may be able to select a gas source cartridge  4  that matches a carbonation level the user desires. (Different carbonation levels may be provided in the different cartridges by having different amounts of gas source in the cartridge  4 .) For example, cartridges providing low, medium and high carbonation levels may be provided for selection by a user, and the user may pick the cartridge that matches the desired carbonation level, and provide the selected cartridge to the system  1 . Thus, a gas source cartridge labeled “low” may be chosen and used with the system to create a low level carbonated beverage. 
     A user may alternately be permitted to define characteristics of a beverage to be made by interacting in some way with a cartridge  4  to be used by the system  1 . For example, tab, notch or other physical feature of the cartridge may be altered or formed by the user to signify a desired beverage characteristic. For example, a broken tab, slider indicator, a covered or uncovered perforation on a portion of the cartridge, etc., that is created by the user may indicate a desired carbonation level, an amount of beverage medium to use in forming the beverage (where the system  1  is controllable to use less than all of the beverage medium in the cartridge to form a beverage), and so on. Features in the cartridge  4  may also be used by the control circuit  5  to detect features of the cartridge, a beverage being formed or other components of the system  1 . For example, light guides in a cartridge  4  may provide a light path to allow the controller  5  to optically detect a level of beverage medium in the cartridge  4 , a flow of precursor liquid in the cartridge  4 , pressure in the cartridge (e.g., where deflection of a cartridge portion can be detected and indicates a pressure), a position of a piston, valve or other cartridge component, an absence of beverage medium in the cartridge (to signify completion of beverage formation), and so on. Other sensor features may be incorporated into the cartridge, such as electrical sensor contacts (e.g., to provide conductivity measurements representative of a carbonation level or other properties of a precursor liquid), an acoustic sensor (to detect gas emission, fluid flow, or other characteristics of the cartridge), and so on. 
       FIG. 7  shows another illustrative arrangement for flow circuitry in a beverage making system  1  that is similar to that of  FIG. 6 . However, in this embodiment, the activating fluid supply  20  includes a dedicated pump  13  that is distinct from a pump  14  that is part of the precursor liquid supply  10 . Also, unlike the arrangement of  FIG. 6 , the precursor liquid supply  10  includes first and second check valves  51   f  and  51   g  upstream and downstream of the pump  14 , which may be a diaphragm pump. The check valves  51   f ,  51   g  may help prevent backflow from the carbonation tank  6 , e.g., when the tank  6  is relatively highly pressurized during the carbonating process. Otherwise, the configuration and operation of the flow circuitry of  FIG. 7  is identical to that of  FIG. 6 . 
       FIG. 8  shows yet another configuration for a beverage making system  1 . Again, this arrangement is similar to that of  FIG. 6 , with a main difference being that, in accordance with an aspect of the invention, the carbonating gas supply includes a water trap  81  through which carbonation gas from the cartridge  4  is routed prior to passing through a gas control valve  51   d  and to the carbonation tank  6 . The water trap  81  may help remove water droplets from the carbonation gas, which may be drained through a vent valve  51   a . That is, activating fluid is directed to the upper compartment  41  of the cartridge  4  by closing a vent valve Ma and pump line valve  51   b , opening an activating fluid valve  51   c , and operating the pump  13  to pump liquid  2  to the upper compartment  41 . Carbonating gas is directed to the carbonation tank  6  by closing the vent valve  51   a  and pump line valve  51   b , and opening the gas supply valve  51   d . Note also that, in accordance with an aspect of the invention, the pressure of the carbonating gas is connected to the inlet side of the pump  13  while the pump  13  delivers activating fluid to the cartridge  4 . This may help equalize or nearly equalize pressures on inlet and outlet sides of the pump  13 , making pump  13  operation require less power during activating fluid delivery. With carbonation complete, the carbonation tank  6  may be vented by opening the gas control valve  51   d  and the vent valve  51   a . To dispense carbonated precursor liquid  2  from the tank  6 , the vent valve  51   a , pump line valve  51   b  and dispense valve  51   e  may be opened, the activating liquid supply valve  51   c  and gas control valve  51   d  closed, and the pump  13  operated to pump air into the carbonation tank  6  so liquid flows to the dispense line  38 . Note that the activating liquid supply valve  51   c  and pump line valve  51   b  could be replaced with a single three way valve, like the three way valve  51   c  in  FIG. 6 . Also, this arrangement shows a mixing chamber  9  located immediately at the outlet of the lower compartment  42  of the cartridge  4 . Other arrangements are possible, however, including having the mixing chamber  9  be arranged as part of the cartridge, e.g., precursor liquid  2  could be routed from the dispense line  38  directly into a portion of the cartridge  4 . 
     In one aspect of the invention, the carbonation tank is surrounded by a cooling container that contains a cooling liquid and thermally conductive fins extend between the carbonation tank and the cooling container. In some arrangements, the cooling liquid may be frozen, in whole or in part, and the fins may extend radially outwardly from the carbonation tank and/or radially inwardly from an outer wall of the cooling container. Thus, at least some of the fins extending between the carbonation tank and the cooling container may be arranged to conduct heat from the tank to the cooling liquid.  FIG. 9  shows a cross sectional side view of a carbonation tank and cooling container in an illustrative embodiment. While other arrangements are possible, in this embodiment the carbonation tank  6  includes fins  63  that extend outwardly toward an outer wall of the cooling container  71 , and the cooling container  71  includes fins  73  that extend inwardly toward the inner wall of the carbonation tank  6 . The cooling liquid  72  is contained between the cooling container  71  outer wall and the carbonation tank  6  inner wall and is in contact with at least some of the fins  63 ,  73 . The carbonation tank  6  also includes an impeller or mixer  62  that is rotatable by a mixer drive  64  so as to mix the precursor liquid  2  in the carbonation tank  6 . Movement of the liquid  2  by the mixer  62  may form a vortex or other configuration such that the liquid  2  moves upwardly along the inner wall of the carbonation tank  6  and forms a void around a center of rotation of the mixer  62 . This arrangement may have two (or more) effects, including increasing an exposed surface area of the liquid  2  at the void, thereby enhancing dissolution of carbon dioxide in the liquid  2 , and increasing an area of contact between the liquid  2  and the inner wall of the carbonation tank  6 , thereby enhancing heat transfer. Movement of the liquid  2  may also cause mixing and/or turbulence, which may also enhance gas dissolution and/or heat transfer. The mixer  62  may be driven by any suitable arrangement, such as a magnetically-coupled motor drive, a drive shaft that extends through a bottom wall of the carbonation tank  6 , or other. 
       FIG. 10  shows an exploded view of the carbonation tank/cooling container assembly in this embodiment. The carbonation tank  6  may be made as an extruded member, including both the inner wall and fins  63 , and may be received within a space defined by the cooling container  71 , which may also be made as an extruded member with the outer wall and fins  73 . With the tank  6  positioned in the cooling container  71 , sealing gaskets  66  and end caps  65  may be assembled at the top and bottom of the tank  6 /container  71  to seal closed the carbonation tank  6  and the space between the carbonation tank  6  and the cooling container  71  where the cooling liquid  72  is located. Prior to being sealed closed by the end caps  65 , the carbonation tank  6  may have the mixer  62  suitably positioned, and cooling liquid  72  may be provided around the tank  6 . The mixer drive  64  may include a motor  64   a , drive belt  64   b  and drive pulley  64   c  (or other arrangement) to rotate the mixer  62 . Insulation  74  may also be provided around the cooling container  71 , if desired. 
       FIG. 11  shows a top view of a carbonation tank  6  assembled with a cooling container  71 , and  FIG. 12  shows a perspective view of the carbonation tank  6  alone in another embodiment. In this embodiment, the inner wall of the carbonation tank  6  has a cylindrical shape, but other shapes are possible. Also, the cooling container  71  includes cooling device mounts  67  on opposed sides, but such mounts are not necessary, e.g., may be provided on the carbonation tank  6 , if desired. The cooling device mounts  67  are configured to receive thermoelectric cooling devices that are directly mounted to the exposed surface of the mounts  67  so the thermoelectric devices can receive heat from the precursor liquid in the tank  6  and/or the cooling liquid  72 , but other arrangements are possible, such as thermally coupling one or more heat pipes, a refrigeration coil, a heat sink or other devices to receive heat from the carbonation tank  6  is possible. 
     In this embodiment, the carbonation tank  6  includes a plurality of fins  63  that have a portion which is attached to the tank and extends radially away from the tank wall. Similarly, the cooling container  71  includes a plurality of fins  73  that have a portion which is attached to the outer wall of the container  71  and extend inwardly. The fin portions  63  engage with the fin portions  73  so that the fin portions  63 ,  73  can exchange heat at the area of contact of the fin portions  63 ,  73 . That is, the fin portions  63 ,  73  have side surfaces that contact each other, e.g., overlapping portions, so that the portions  63 ,  73  can transfer heat. In this arrangement, the side surfaces of at least some of the fin portions  63 ,  73  are pressed together so as to be in contact, but are separable from each other, e.g., are not welded or adhered to each other. In some cases like that shown in  FIG. 10 , the cooling container and tank may be assembled by inserting the tank  6  inside of the cooling container  71  and such that the side surfaces of corresponding fin portions  63 ,  73  fins are pressed into contact with each other. For example, side surfaces of an adjacent pair of fin portions  63  of the carbonation tank  6  may be positioned inside of, and in contact with, opposed side surfaces of an adjacent pair of fin portions  73  of the cooling container  71 . Contact of the fin portions  63 ,  73  may cause the fin portions  63 ,  73  to flex, thereby biasing the side surfaces of the fin portions  63 ,  73  into contact with each other. Of course, other arrangements are possible, and as can be seen in  FIG. 11 , not every fin portion  63 ,  73  need contact another fin portion  63 ,  73 . Also, in this embodiment, the cooling container  71  is arranged have a continuous outer wall that encloses the carbonation tank  6  as in  FIG. 10 , but the container  71  could be arranged as a clam shell type arrangement with two wall sections that sandwich the carbonation tank  6  so that a portion of the tank  6 , such as a portion that includes mounts  67 , are exposed. Thus, this configuration can be changed, e.g., the container  71  can include the mounts  67  which are pressed into contact with the inner wall of the carbonation tank  6  and/or fins  63  to receive heat from the tank  6 . Alternately, the container  71  and the carbonation tank  6  could be molded or extruded as a single, unitary part, e.g., made of injection molded plastic. 
     In accordance with another aspect of the invention, a cooling system for chilling precursor liquid may include a thermoelectric device thermally coupled to a carbonation tank to cool precursor liquid in the tank, one or more heat pipes each having an evaporator section thermally coupled to the thermoelectric device to receive heat from the thermoelectric cooler, and a heat sink thermally coupled to the condenser section of the one or more heat pipes to receive heat from the heat pipe. Such an arrangement has been found to be particularly effective in rapidly cooling precursor liquid, especially with the relatively low power draw requirements for household appliances in some jurisdictions, e.g., 115-120 volts, 15-20 amps maximum. That is, using heat pipes to thermally couple the “hot” side of a thermoelectric device to a heat sink has been found to be significantly more effective in suitably cooling the thermoelectric device than having a heat sink in direct contact with the “hot” side of the thermoelectric device. 
       FIG. 13  shows one illustrative embodiment in which two thermoelectric devices  75  (only one is shown in  FIG. 13 ) are coupled to the thermoelectric device mounts  67  of the carbonation tank  6 . Heat pipes  76  (six for each thermoelectric device  75  in this embodiment though other numbers are possible) have respective evaporator sections coupled to the thermoelectric device, and have respective condenser sections coupled to a heat sink  77 , e.g., a set of radiator fins. Air may be moved over the heat sinks  77  by a fan  78 , and a duct  79  may suitably direct the flow of air such that relatively cool air enters a duct inlet  79   b  near a bottom of the duct  79  and exits a duct outlet  79   a  at the fan  78 . 
       FIG. 14  shows another cooling system  7  arrangement that also has two thermoelectric devices  75  and corresponding heat pipes  76  and heat sinks  77 . However, in this embodiment, the fan  78 , duct  79  and the heat sinks  77  are differently arranged such that the fan  78  is at the duct inlet  79   b  and pushes cooling air into the duct  79  so the air may pass through the heat sinks  77  and exit via a respective duct outlet  79   a  located at each heat sink  77 . This configuration could be used in an arrangement discussed above where a duct outlet  79   a  is located at a top of a system housing  21  and adjacent a precursor liquid inlet opening. For example, the duct  79  in this embodiment is arranged so that liquid entering the duct outlet  79   a  can flow downwardly in the duct  79  to a bottom of the housing  21 . Openings in the duct  79  at the bottom of the housing  21  may allow the liquid to exit, e.g., and exit the housing  21 . The duct  79  is isolated from electronic components of the system  1 , and the heat pipes  76  may pass through the duct walls to couple with a heat sink  77  positioned in the duct  79 . 
       FIG. 15  shows another arrangement with a fan  78  positioned at a duct inlet  79   b . However, in this case, the heat sinks  77  are positioned near the fan  78  so incoming air flows over the heat sinks  77 , and then flows upwardly through the duct  79  to a duct outlet  79   a  at a top of the duct  79 . This arrangement, like  FIG. 14 , may also be used in a configuration where a duct outlet  79   a  is located at a top of a system housing  21  and adjacent a precursor liquid inlet opening. Any liquid entering the duct outlet  79   a  may flow down the duct  79  and out through one or more openings at a low point of the duct  79 . Those of skill in the art will appreciate that other arrangements are possible, including those with more or fewer thermoelectric devices  75 , heat pipes  76 , or heat sinks  77 . 
     In one aspect of the invention, a method for chilling precursor liquid includes providing a cooling liquid bath around a tank containing precursor liquid to be chilled. For example, in the embodiments above, the cooling liquid  72  may be provided around the carbonation tank  6 . The cooling liquid may be cooled to freeze at least some of the cooling liquid so as to form ice. For example, the thermoelectric devices  75  may be operated to remove heat from the cooling container  71 , cooling liquid  72  and carbonation tank  6  so that the cooling liquid  72  is at least partially frozen. In the case of water, the cooling liquid  72  may be chilled to about 0 degrees C. to form ice. A temperature of the cooling liquid may be monitored while cooling, and cooling of the cooling liquid may be stopped when the temperature of the cooling liquid drops to a temperature that is more than a first threshold below a freezing temperature of the liquid. For example, the cooling liquid  72  may be chilled to a temperature about −4 degrees C., i.e., more than a threshold of 2-4 degrees below a 0 degree C. freezing temperature for the cooling liquid  72  in the case of water. Of course, a glycol or other anti-freeze compound may be provided to lower the freezing temperature of the cooling liquid, if desired. 
     In some cases, cooling of the cooling liquid may start when the temperature of the cooling liquid is a temperature above a second threshold above a freezing temperature of the liquid. That is, once the cooling liquid is suitably chilled below its freezing temperature, the thermoelectric devices or other devices may stop operating until the cooling liquid warms to a temperature that is more than a second threshold above or below the cooling liquid&#39;s freezing temperature. In the example above, cooling of the cooling liquid may start upon the cooling liquid warming to a temperature of that is 1-2 degrees below its 0 degree C. freezing temperature. Of course, other thresholds may be used than a threshold of 1 to 2 degrees C. For example, the first and/or second threshold may be 1 to 4 degrees C. 
     As described above, heat may be removed from the cooling liquid in different ways, such as by operating a thermoelectric device and removing heat from the thermoelectric device by at least one heat pipe and a heat sink. The thermoelectric device may remove heat from the cooling liquid by removing heat from the cooling container and/or from the carbonation tank. 
     While systems for making a beverage may be used with different cartridge configurations,  FIGS. 16 and 17  shows a cartridge  4  that may be used with a beverage making system  1 . In this embodiment, the cartridge  4  includes a container that defines an upper compartment or chamber  41 , a lower compartment or chamber  42 , and a rim or band  44  between a top and bottom of the cartridge  4 . The top of the cartridge  4  includes a lid  45  that covers an opening of the container. The lid  45  is piercable to form one or more openings so as to access a gas source (not shown) in the upper compartment  41 . (Although in this embodiment, the lid  45  is a separate element, such as a sheet of foil/polymer laminate attached to the container body, the lid may be molded or otherwise formed integrally with the body.) Also, a filter  45   a  may be positioned below the lid  45 , e.g., spaced apart from the lid  45  but parallel to the lid  45  although other arrangements are possible. This filter  45   a  may help prevent gas source material from exiting the upper compartment  41  during gas production. The upper compartment  41  is also defined in part by a wall  49  that has a concave up curve, but such a shape is not necessary, e.g., the wall  49  may be flat or concave down. The cartridge  4  also includes a piercable inlet  47  located at an underside of the rim  44  and at an indexing groove  46  of the cartridge  4 . As is discussed in more detail below, the inlet  47  may be pierced to allow access to the lower compartment  42 , e.g., so pressurized gas or liquid can be introduced into the lower compartment  42  to move a beverage medium (not shown) out of an outlet  48  of the lower compartment  42 . In this embodiment, the outlet  48  includes a piercable membrane that can be pierced and opened to allow the beverage medium to exit, although other arrangements are possible, e.g., a self-closing septum valve or burstable seal may be provided at the outlet  48  that opens with increased pressure in the lower compartment  48 . Cartridges are not limited to the arrangement shown in  FIGS. 16 and 17 , however, and a beverage making system  1  may be arranged to operate with cartridges  4  that include only a gas source (e.g., only a rim  44  and upper compartment  41 ) to make a carbonated water, or only a beverage medium (e.g., only a rim  44  and lower compartment  42  like that shown in  FIG. 18 ) to make a still, flavored beverage. 
     The cartridge  4  may be made of any suitable materials, and is not necessarily limited to the constructions shown herein. For example, the cartridge may be made of, or otherwise include, materials that provide a barrier to moisture and/or gases, such as oxygen, water vapor, etc. In one embodiment, the cartridge may be made of a polymer laminate, e.g., formed from a sheet including a layer of polystyrene, polypropylene and/or a layer of EVOH and/or other barrier material, such as a metallic foil. Moreover, the cartridge materials and/or construction may vary according to the materials contained in the cartridge. For example, a portion of the cartridge  4  containing a gas source material may require a robust moisture barrier, whereas a beverage medium portion may not require such a high moisture resistance. Thus, the cartridges may be made of different materials and/or in different ways. In addition, the cartridge interior may be differently constructed according to a desired function. For example, a beverage medium cartridge portion may include baffles or other structures that cause the liquid/beverage medium to follow a tortuous path so as to encourage mixing. The gas source cartridge portion may be arranged to hold the gas source in a particular location or other arrangement in the interior space, e.g., to help control wetting of the gas source with activating liquid. Thus, as used herein, a “cartridge” may take any suitable form, such as a pod (e.g., opposed layers of filter paper encapsulating a material), capsule, sachet, package, or any other arrangement. The cartridge may have a defined shape, or may have no defined shape (as is the case with some sachets or other packages made entirely of flexible material). The cartridge may be impervious to air and/or liquid, or may allow water and/or air to pass into the cartridge. 
     A cartridge may also be arranged to provide a visual or other detectable indication regarding the cartridge&#39;s fitness for use in forming a beverage. For example, the cartridge may include a pop-up indicator, color indicator or other feature to show that the gas source has been at least partially activated. Upon viewing this indication, a user may determine that the cartridge is not fit for use in a beverage making machine. In another embodiment, an RFID tag may be associated with a sensor that detects gas source activation (e.g., via pressure increase), beverage medium spoilage (e.g., via temperature increase), or other characteristic of the cartridge, which may be transmitted to a reader of a beverage making machine. The machine may display the condition to a user and/or prevent activation of the machine to use the cartridge to form a beverage. 
     In one aspect of the invention, the cartridge or cartridges used to form a beverage using the beverage making system may have a volume that is less, and in some cases substantially less, than a beverage to be made using the cartridge(s). For example, a cartridge may have upper and lower compartments  41 ,  42  that each have a volume that is about 50 ml or less, and yet can be used to form a beverage having a volume of about 200-500 ml or more. The inventors have found (as shown in some of the Examples below) that an amount of charged carbon dioxide adsorbent (e.g., a charged zeolite) of about 30 grams (which has a volume of less than 30 ml) can be used to produce about 300-500 ml of carbonated water having a carbonation level of up to about 3.5 volumes. Moreover, it is well known that beverage-making syrups or powders having a volume of less than about 50 ml, or less than about 100 ml, can be used to make a suitably flavored beverage having a volume of about 300-500 ml. Thus, relatively small volume cartridges (or a single cartridge in some arrangements) having a volume of about 100 ml to about 250 ml or less may be used to form a carbonated beverage having a volume of about 100 to 1000 ml, and a carbonation level of at least about 1.5 to 4 volumes in less than 120 seconds, e.g., about 60 seconds, and using pressures under 80 psi. 
     In accordance with an aspect of the invention, a cartridge may be held by a cartridge holder of a beverage making machine such that an upper compartment of the cartridge is held in a space and has a pressure that is different from a space where a lower compartment of the cartridge is held. For example, the upper compartment may be held in a sealed space arranged to receive relatively high pressure gas used to carbonate the precursor liquid, while the lower compartment is held at ambient pressure. Such an arrangement may help isolate the lower compartment from relatively high pressures, e.g., preventing premature dispensing of beverage medium by introduction of high pressure gas into the lower compartment  42 .  FIGS. 19 and 20  show a cross sectional side view of a cartridge holder  3  that may be included with the system  1  shown in  FIGS. 1-4  and which may operate with a cartridge like that shown in  FIGS. 16-18 . In this embodiment, a lower portion of the cartridge holder includes a sliding drawer  31  shown in an open position with a cartridge  4  positioned in a basket  32 , i.e., a cartridge receiver. The cartridge may be received in the basket  32  so that the rim  44  rests on an upper ledge or surface of the basket  32  so the basket  32  supports the weight of the cartridge  4 . With the cartridge  4  in the basket  32 , the drawer  31  may be moved to a closed position shown in  FIG. 20 . Thereafter, an upper portion of the cartridge holder  3  may move downwardly to clamp the cartridge  4  in place, e.g., to house the upper compartment  41  in a sealed space. In this embodiment, the upper portion of the cartridge holder includes a threaded sleeve  34  that carries a piston  36  and can move downwardly relative to the cartridge  4  so that a lower surface of the piston  36  contacts the cartridge rim  44  and clamps downwardly on the rim  44  to form a seal between the piston  36  and the rim  44 . In the embodiment, a wave spring or other resilient element is positioned between the threaded sleeve  34  and the piston  36  that urges the piston  36  to move downwardly relative to the sleeve  34 . The threaded sleeve  34  and piston  36  move downwardly by rotation of a rotatable sleeve  35  positioned around a part of the threaded sleeve  34 . Specifically, as can be seen in  FIG. 21 , a worm gear of a motor drive  37  may engage a gear of the rotatable sleeve  35  so that the motor drive  37  can rotate the rotatable sleeve  35  relative to the threaded sleeve  34 . Since the rotatable sleeve  35  and the threaded sleeve  34  are engaged by a thread connection, rotation of the rotatable sleeve  35  causes the threaded sleeve  34  to move downwardly (or upwardly, depending on the direction of rotation of the rotatable sleeve  35 ) relative to the cartridge  4 . 
     As the threaded sleeve  34  and the piston  36  move downwardly, the upper compartment  41  of the cartridge  4  may be received into the threaded sleeve  34 /piston  36  until the piston  36  contact the cartridge rim  44  and urges the cartridge  4  to move downwardly against the lower portion of the cartridge holder. (Downward movement of the sleeve  34  relative to the piston  36  compresses the wave spring or other resilient element between the sleeve  34  and the piston  36 .) This downward movement can cause two actions, i.e., piercing of the inlet  47  and the outlet  48  of the lower compartment  42 . That is, the basket  32  may be movable in a vertical direction relative to the drawer  31 , yet be spring biased to move upwardly and remain in an upper position even with the cartridge  4  in the basket  32 . However, the clamping force of the upper portion of the cartridge holder (e.g., the threaded sleeve  34  and piston  36 ) can overcome the spring bias on the basket  32 , causing the basket  32  and the cartridge  4  to move downwardly relative to the drawer  31 . This downward movement may cause a dispense gas piercing element  33  to contact the cartridge at the inlet  47  and pierce the inlet  47  so that the dispense gas piercing element  33  can deliver pressurized gas into the lower compartment  42 . (A gasket or other seal at the piercing element  33  can engage the cartridge  4  at the inlet  47  to form a leak-resistant connection at the inlet  47 . As will also be understood, the dispense gas piercing element  33  may be connected to a line that provides pressurized gas, e.g., from an air pump  43 .) In accordance with an aspect of the invention, the cartridge may be pierced at an underside of the rim  44  to provide an opening through which pressurized gas can be introduced to move beverage medium out of the lower compartment  42 . Since the rim  44  may be made relatively robustly to establish a desired seal with the cartridge holder and to oppose a piercing force of the piercing element  33 , a remainder of the cartridge  4  may be made out of relatively weak or less robust material or construction, e.g., to reduce cost and/or weight of the cartridge. Thus, the cartridge may be arranged to allow for reliable piercing for introduction of pressurized gas into the lower compartment  42  and sealing with the cartridge holder at the rim  44 , yet still keep materials requirements to a minimum. 
     Downward movement of the cartridge  4  and basket  32  may also cause an outlet piercing element  39  to contact the piercable membrane or other cartridge portion at the outlet  48  so that the outlet  48  is opened. In this embodiment, the outlet piercing element  39  includes an annular rim that contacts the piercable membrane and is received into an annular groove of the cartridge  4  above the piercable membrane. Movement of the annular rim into the groove stresses the piercable membrane such that the membrane, which may be scored or otherwise have a line of weakness that defines a preferential opening area, to be pierced and pulled back so the outlet  48  can dispense beverage medium to the dispense station  29 . A dispense line  38  for precursor liquid may also lead to the dispense station  29  so the precursor liquid  2  and beverage medium can be dispensed together, or separately, into a user&#39;s cup  8 . 
     Downward movement of the upper portion of the cartridge holder  3  may also cause piercing of the cartridge lid  45  or other action such that the upper compartment  41  can be accessed. In this illustrative embodiment, the piston  36  includes a pair of piercing elements  361  arranged to pierce the lid  45  to introduce activating fluid into the upper compartment  41 , and a piercing element  362  arranged to pierce the lid  45  to allow gas emitted by the gas source to exit the cartridge  4 . Though not necessary, the piercing elements  361  are arranged to penetrate through the lid  45  and the filter  45   a  so that activating fluid can be introduced below the filter  45   a . However, the piercing element  362  is arranged to pierce only the lid  45 , but not the filter  45   a . In this way, gas emitted in the upper compartment  41  must pass through the filter  45   a  before exiting to the carbonating gas supply. This may help prevent gas source material, such as zeolite particles, from exiting the cartridge  4  and passing to the carbonating gas supply  30 . A variety of arrangements are possible for the filter  45   a , such as a piece of filter paper mentioned above, a hydrophobic non-woven material that permits gas to pass, but resists liquid passage, or other element that permits gas to exit the cartridge  4 , but resists movement of gas source material and/or liquid. In addition or alternately to the filter  45   a , a conduit that receives the carbonating gas may include a filter element, such as a filter plug in the conduit, to help further resist movement of gas source materials to the carbonation tank  6 . The piercing elements, may include a hollow needle, spike, blade, knife or other arrangement, to form a suitable opening in the cartridge  4 . In this embodiment, the piercing elements  361  include tubular elements with an activating fluid discharge opening at a distal end such that activating fluid can be released from the piercing elements  361  below the filter  45   a . In contrast, the piercing element  362  is relatively dull so as to penetrate the lid  45 , but not the filter  45   a . Alternately, the cartridge  4  may have defined openings, e.g., one or more ports, that include a septum or other valve-type element that permits flow into and/or out of the cartridge  4 . 
     It should be understood that a cartridge holder  3  is not necessarily limited to the embodiments described herein. For example, the cartridge holder may open and close in any suitable way to allow cartridges  4  to be placed in and/or removed from the holder  3 . In one embodiment, a cartridge holder may include a lid pivotally mounted to a receiver portion of the holder  3 , and may be opened and closed manually, such as by a handle and linkage arrangement, or automatically, such as by a motor drive, to close the cartridge holder  3 . Of course, the lid may be arranged in other ways, such as being engaged with the cartridge receiver by a threaded connection (like a screw cap), by the cartridge receiver moving relative to the lid while the lid remains stationary, by both the lid and receiver portion moving, and so on. In addition, a cartridge holder  3  need not necessarily have a lid and receiver arrangement, but instead may have any suitable member or members that cooperate to open/close and support a cartridge. For example, a pair of clamshell members may be movable relative to each other to allow receipt of a cartridge and physical support of the cartridge. Some other illustrative cartridge holder arrangements are shown, for example, in U.S. Pat. Nos. 6,142,063; 6,606,938; 6,644,173; and 7,165,488. As mentioned above, the cartridge holder  3  may allow a user to place one or more cartridges in the holder  3  without the need for the user to take special steps to establish a pressure-tight, leak-proof or other specialized connection between the cartridge and other portions of the system  1 . Instead, in some embodiments, the user may be able to simply place the cartridge in a receiving space, and close the cartridge holder. 
     While in the embodiment shown in  FIGS. 20 and 21  a beverage medium and precursor liquid are dispense separately into a user&#39;s cup, in one aspect of the invention, beverage medium and precursor liquid are mixed in a mixing chamber and then dispensed to a user&#39;s cup. While such mixing may not completely combine beverage medium and precursor liquid together to form a completely homogenous beverage, the beverage medium and precursor liquid may be combined at least in some way, e.g., like that found in some soda fountains. As can be seen in  FIGS. 22-24 , an alternate embodiment that includes a mixing chamber  9  downstream of a cartridge outlet  48  can operate to mix precursor liquid and beverage medium. The mixing chamber  9  in this embodiment has three main sections, i.e., a syrup chamber  96  that receive beverage medium from a cartridge  4 , a precursor liquid inlet that is coupled to the dispense line  38 , and a dispense outlet  93  where precursor liquid and/or beverage medium are dispensed. Pressurized gas introduced into the lower compartment  42  by the dispense gas piercing element  33  causes beverage medium (in this case a syrup) to exit through the outlet  48  and enter the syrup chamber  96 . Pressure in the lower compartment  42  and in the syrup chamber  96  forces beverage medium to move to the syrup chamber outlet  95  where the beverage medium can flow to the dispense outlet  93 . The syrup chamber outlet  95  may include multiple channels that lead downwardly from the syrup chamber  96 , e.g., so that relatively thin streams of syrup pass to the dispense outlet  93 . These thin streams of beverage medium may allow for faster mixing or other combination with precursor liquid that flows from the dispense line  38  to the dispense outlet  93 . The syrup chamber  96  also has a syrup chamber inlet  94  that is in communication with the precursor liquid that enters the mixing chamber  9  via the dispense line  38 . So long as relatively high pressure is present in the syrup chamber  96  (due to pressurized gas being introduced into the lower compartment  42 ), precursor liquid will generally not enter the syrup chamber  96  via the syrup chamber inlet  94 . However, once pressure in the syrup chamber  96  drops to a suitable level, precursor liquid may enter the syrup chamber  96  through the syrup chamber inlet  94 . (As will be understood, the size, shape and/or position of the syrup chamber inlet  94  opening(s) may influence how, whether and when precursor liquid enters the syrup chamber  96 .) Precursor liquid in the syrup chamber  96  may mix with any beverage medium that is present, as well as wash or rinse the syrup chamber  96  and syrup chamber outlet  95  of beverage medium. Accordingly, dispensing of beverage medium from the cartridge  4  may be suitably timed to start during flow of precursor liquid into the mixing chamber  9 , and end before the flow of precursor liquid into the mixing chamber stops. In this way, the beverage medium may mix with precursor liquid as it is dispensed from the cartridge  4 , and once beverage medium dispensing is complete, precursor liquid may rinse the syrup chamber  96  and syrup chamber outlet  95 , e.g., so that little or no beverage medium is present in the syrup chamber  96  once beverage dispensing is complete. 
     As can be seen in  FIGS. 22-24 , the component that defines the mixing chamber  9  may also include the outlet piercing element  39  that opens the outlet  48  of the cartridge. That is, the mixing chamber  9  may include an annular rim  91  that functions to contact a membrane at the cartridge outlet  48  and move into an annular groove of the cartridge  4  as the cartridge moves downwardly so that the outlet  48  is suitably opened for beverage medium dispensing. Moreover, the mixing chamber  9  may be removable from the dispensing station  29 , e.g., for cleaning or replacement. 
     It should be understood that modifications to the illustrative embodiment above are possible. For example, the beverage medium could be driven from the cartridge  4  in other ways, such as by carbon dioxide gas pressure created by the cartridge  4 , by gravity, by suction created by an adductor pump, venturi or other arrangement, etc., and the beverage medium may be dispensed directly into a user&#39;s cup where the precursor liquid  2  is also introduced. Rinsing of the mixing chamber  9  may or may not be necessary, e.g., to help prevent cross contamination between beverages. In some arrangements, the entire volume of beverage medium may be discharged into the mixing chamber, causing initial amounts of flavored precursor liquid  2  exiting the mixing chamber  9  to have a high beverage medium concentration. However, as the beverage medium is swept from the mixing chamber by the precursor liquid  2 , the precursor liquid itself may effectively rinse the mixing chamber. In arrangements where the beverage medium is a dry material, such as a powder, some precursor liquid may be introduced into the cartridge to pre-wet the medium or otherwise improve an ability to mix the medium with precursor liquid  2 . The wetted medium may be mixed with additional precursor liquid  2  in the cartridge, or the wetted medium may be expelled from the cartridge, e.g., by air pressure, a plunger, etc., to a mixing chamber or other location for additional mixing with precursor liquid  2 . Liquid  2  may be introduced into a mixing chamber using multiple streams, e.g., to enhance a mixing rate using low flow speeds so as to reduce loss of dissolved gas. 
     Also, the mixing chamber  9  may take other suitable forms, e.g., may cause the precursor liquid  2  and beverage medium to move in a spiral, swirl or other fashion to enhance mixing, may have one or more motor driven blades, impellers or other elements to mix contents in the chamber  9 , and so on. While the mixing chamber  9  may be separate from the cartridge  4 , the mixing chamber  9  could be incorporated into a cartridge  4  if desired. The mixing chamber  9  may be cooled as well, e.g., by a refrigeration system, to help cool the beverage provided to the cup  8 . In the case where the carbonated liquid  2  is not flavored or where the liquid  2  is mixed with the beverage medium before passing through the carbonation tank  6 , the mixing chamber  9  may be eliminated or arranged to mix the precursor liquid  2  and beverage medium upstream of the tank  6 . Alternately, the precursor liquid supply  10  may be arranged to mix the precursor liquid  2  with the beverage medium in the cartridge  4  prior to routing the liquid  2  to the tank  6 . 
     Example 1 
     The release properties of a carbon dioxide adsorbent were measured in the following way: 8×12 beads of sodium zeolite 13X (such as are commercially available from UOP MOLSIV Adsorbents) were obtained. The beads were placed in a ceramic dish and fired in a Vulcan D550 furnace manufactured by Ceramco. The temperature in the furnace containing the beads was raised to 550° C. at a rate of 3° C./min and was held at 550° C. for 5 hours for firing and preparation of the beads for charging with carbon dioxide. 
     The beads were removed from the furnace and immediately transferred to a metal container equipped with a tightly fitted lid and entrance and exit ports permitting circulation of gas. With the beads sealed in the container, the container was flooded with carbon dioxide gas and pressurized to 15 psig. (Note, however, that experiments have been performed between 5-32 psig.) The chamber was held at the set pressure for 1 hour. During this hold period the chamber was bled every 15 min. At the end of this period a quantity of gas had adsorbed to the beads. 
     A 30 g sample of charged 13X zeolite was measured, and a beaker filled with 250 ml of water at room temperature of 22° C. The beaker and water was placed on a balance and the balance zeroed. The 30 g of charged zeolite was then added to the beaker and the change in weight versus time was measured. It was shown that the change in weight became approximately steady after a period of 50 seconds, and that the beads lost about 4.2 g (14 wt %) of weight attributed to the release of carbon dioxide. Of course, some carbon dioxide may have been dissolved into the water. 
     
       
         
           
               
               
               
             
               
                   
                   
               
               
                   
                 Time (sec) 
                 Weight (grams) 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 0 
                 30 
               
               
                   
                 25 
                 26.7 
               
               
                   
                 50 
                 25.8 
               
               
                   
                 75 
                 25.6 
               
               
                   
                 100 
                 25.5 
               
               
                   
                   
               
            
           
         
       
     
     Example 2 
     Charged zeolite 13X was prepared as in Example 1. A 30 g sample of the charged zeolites was then placed in metal chamber with a water inlet port at the bottom and a gas outlet port at the top. The chamber that held the zeolites was 34×34 mm in cross section and had 2 metal filter discs with 64 1/16″ diameter holes to retain the zeolite material. Tap water was then flooded into the bottom of the chamber perpendicular to the cross-section at an average flow rate of 60 ml/min. Gas evolved through the top outlet port. 
     The pressure of the gas in the chamber was measured with a pressure gauge and controlled using a needle valve attached to the exit port of the gas chamber. The needle valve was set to maintain the chamber at a pressure of 35 psig by manually adjusting the valve over the course of exposing charged zeolites in the chamber to water. Once the valve was set to an operating pressure, the system would perform repeatably with zeolite samples charged in the same manner. 
     Example 3 
     Charged zeolite 13X was prepared as in Example 1. A 30 g sample of the charged zeolites was then placed in a semi rigid 50 ml polystyrene-polyethylene-EVOH laminate cup container and thermally sealed with a foil lid. The sealed zeolite cartridges were then placed into a sealed, metal cartridge chamber and pierced on the top and bottom. 
     Tap water was introduced at the bottom of the cartridge with the flow controlled by a solenoid valve. The solenoid valve was actuated via a pressure switch connected to the top gas outlet of the cartridge chamber. During three different tests, the pressure switch was set to three different operating pressures of 5, 22, and 35 psig. The resulting gas at the set pressures was then introduced into the shellside of a hydrophobic membrane contactor (1×5.5 Minimodule from Liquicel, of Charlotte, N.C.). The other shellside port was plugged to prevent gas from escaping. Water from a reservoir containing 400 ml of water and approximately 50 g of ice was circulated from the reservoir, through the contactor, and back to the reservoir (e.g., like that shown in  FIG. 2 ) using an Ulka (Milan, Italy) type EAX 5 vibratory pump through the lumenside of the membrane contactor. The pressure of the reservoir and contactor was maintained at the same pressure as the gas was produced. The system produced gas and circulated the water for approximately 60 seconds before being stopped. 
     The resulting carbonated water was then tested for carbonation levels using a CarboQC from Anton-Paar of Ashland, Va. The results for are shown in the table below: 
     
       
         
           
               
               
               
             
               
                   
                   
               
               
                   
                   
                 Average Carbonation Level 
               
               
                   
                 System Pressure (psig) 
                 (Volumes CO 2  dissolved) 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 10 
                 1.35 
               
               
                   
                 22 
                 2.53 
               
               
                   
                 35 
                 3.46 
               
               
                   
                   
               
            
           
         
       
     
     Thus, the gas was shown to evolve from the zeolites in the cartridges at a controllable rate (based on water delivery to the cartridge chamber) and then dissolved into water to produce a carbonated beverage. In addition, this illustrates the concept that by controlling system pressures one can control the level of carbonation of the finished beverage. It is expected that higher system pressures, e.g., of about 40-50 psi above ambient, would produce a 4 volume carbonated beverage (having a liquid volume of about 500 ml) in about 60 seconds or less. 
     Having thus described several aspects of at least one embodiment of this invention, it is to be appreciated that various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be part of this disclosure, and are intended to be within the spirit and scope of the invention. Accordingly, the foregoing description and drawings are by way of example only.