Patent Publication Number: US-2018044207-A1

Title: Controlling regeneration of an electrode in unidirectional ph adjustment of water

Description:
FIELD OF THE INVENTION 
     The present invention is directed generally to controlling regeneration of an electrode in unidirectional pH adjustment of water. More particularly, various inventive methods and apparatus disclosed herein relate to obtaining one or more values related to a unidirectional pH adjustment (“UpA”) cell, and controlling when a regeneration period of the UpA cell is started, parameters for the regeneration period, and/or other parameters related to inputs to the UpA cell based on the values. 
     BACKGROUND OF THE INVENTION 
     WO 2014/102636 (Attorneys&#39; docket 2013PF00021), incorporated herein by reference, relates to domestic water property adjustment, especially to a pH adjustor and a home appliance including the pH adjustor capable of unidirectional pH adjustment without producing waste water. The pH adjustor comprises an electrolysis cell including an anode and a cathode: the cathode comprising pseudocapacitance material, in operation of the pH adjustor, the pseudo-capacitance material gets electrons from the anode and adsorbs cations from an electrolyte aqueous solution (e.g. domestic water) by electrochemically reacting with said anions, OH− in the electrolyte aqueous solution are consumed by losing electrons, leaving H+ in the electrolyte aqueous solution; or the anode comprises pseudocapacitance material, and in operation of the pH adjustor, the pseudocapacitance material loses electrons and adsorbs anions from the electrolyte aqueous solution by electrochemically reacting with said anions, H+ in the electrolyte aqueous solution are consumed at the cathode by getting electrons, leaving OH− in the electrolyte aqueous solution. 
     Unidirectional pH adjustment (“UpA”) is a technique for unidirectionally adjusting pH of water during water electrolysis only in one direction. Thus, when UpA is utilized, only acidic water or only alkaline water is produced (which is produced will depend on the desired implementation)—and waste water is not produced or is produced at a reduced level as compared to other electrolysis techniques. When UpA is utilized for adjusting pH of water, only the pH of the water at the counter electrode is changed while that at the working electrode is stable. The working electrode in UpA may be, for example, an active carbon based (“AC”) working electrode that works as a super capacitor during electrochemical reaction. The counter electrode in UpA may be, for example, an inert metal such as titanium (Ti). 
     In UpA there are two periods: a “working period” and a “regeneration period.” During the working period the working electrode is in a charging state while the counter electrode is generating ions required for the desired pH change. For example, where UpA is applied to increase the pH of water, the counter electrode produces required H+ ions during the working period. During the regeneration period, the working electrode is in a discharging state while the counter electrode is generating ions that are undesired for the desired pH change. For example, where UpA is applied to increase the pH of water, the counter electrode produces undesired OH− ions during the regeneration period. 
     As described above, during the regeneration period the working electrode is discharging to enable the working electrode to again be charged during the working period. The regeneration period may be set to occur upon occurrence of a fixed condition, such as when the working electrode is fully charged and/or when the transient voltage drop on the working electrode is close to the decomposing voltage of water. However, this and/or other techniques may suffer from one or more drawbacks. For example, one or more of the techniques may not determine discharging parameters with which the regeneration period is to be performed such as discharging time, a magnitude of reverse voltage applied during the regeneration period, etc. Also, for example, one or more of the techniques may not consider certain measured or otherwise known parameters related to a unidirectional pH adjustment cell to determine a charging status of a working electrode at which regeneration should be performed. Also, for example, one or more of the techniques may not take into account effects on the production rate of desired and/or undesired ions and/or energy efficiency in determining discharging parameters for a regeneration period and/or when the regeneration period should be performed. 
     SUMMARY OF THE INVENTION 
     Thus, there is a need in the art to provide alternative techniques for controlling regeneration of an electrode in unidirectional pH adjustment of water. The invention is defined by the independent claims. The dependent claims define advantageous embodiments. 
     The present disclosure is directed to inventive methods and apparatus for controlling regeneration of an electrode in unidirectional pH adjustment (“UpA”) of water. For example, various inventive methods and apparatus disclosed herein relate to obtaining one or more measured or otherwise known parameters related to a UpA cell, and controlling when a regeneration period is started, parameters for the regeneration period, and/or other inputs to the UpA cell based on the values. Some embodiments relate to determining discharging parameters for a regeneration period, such as discharging time, a magnitude of reverse voltage applied during the regeneration period, etc. Some embodiments relate to determining when a regeneration period should be performed based on one or more measured values related to a UpA cell such as voltage(s) applied by a power source to the UpA cell, current(s) applied by the power source, and/or a rate at which water is supplied to the UpA cell. Some embodiments relate to taking the total desired and/or undesired ions production rate and/or energy efficiency of a UpA cell into account in determining discharging parameters for a regeneration period and/or when the regeneration period should be performed. 
     In one aspect, a method of controlling regeneration of an electrode in unidirectional pH adjustment of water may include: obtaining a plurality of parameters related to a unidirectional pH adjustment cell, the unidirectional pH adjustment cell including a working electrode and a counter electrode; determining, based on optimizing a production rate of desired ions in the unidirectional pH adjustment cell in view of the parameters, a regeneration duration of a regeneration period of the unidirectional pH adjustment cell and a working duration of a working period of the unidirectional pH adjustment cell; and charging the unidirectional pH adjustment cell for the determined working duration; and discharging the unidirectional pH adjustment cell for the determined regeneration duration. 
     In some embodiments, obtaining the plurality of parameters includes receiving at least one value of the parameters from a sensor sensing the parameter. In various versions, the sensor is a flow meter and the value is a flow rate of water provided to the unidirectional pH adjustment cell. In various versions, the sensor is a voltmeter and the value is a voltage of a circuit that includes the working electrode, the counter electrode, and a power supply coupled to the working electrode and the counter electrode. 
     In various embodiments, determining, based on optimizing the production rate of desired ions in the unidirectional pH adjustment cell in view of the parameters, the regeneration duration and the working duration includes: determining the regeneration duration maximizes an average production rate of desired ions during charging of the unidirectional pH adjustment cell; and determining the regeneration duration minimizes a production rate of undesired ions during discharging of the unidirectional pH adjustment cell. In various versions, determining, based on optimizing the production rate of desired ions in the unidirectional pH adjustment cell in view of the parameters, the regeneration duration and the working duration includes: determining a working voltage drop of the working electrode at a start of the working period (V AC0 ) and a regeneration voltage drop of the working electrode at a start of the regeneration period (V ACE ) that minimize a first objective function in view of the parameters and that maximize a second objective function in view of the parameters, the first objective function indicative of an average production rate of desired ions during charging of the unidirectional pH adjustment cell, and the second objective function indicative of an average production rate of undesired ions during discharging of the unidirectional pH adjustment cell; and determining the regeneration duration and the working duration based on the determined V AC0  and V ACE . In various embodiments, determining the regeneration duration and the working duration is further based on optimizing an energy efficiency of the working period and the regeneration period. 
     In various embodiments, the method further includes: determining, based on optimizing the production rate of desired ions in the unidirectional pH adjustment cell in view of the parameters, a voltage to be applied by a power source during the working period. In various embodiments, charging the unidirectional pH adjustment cell for the determined working duration includes charging the unidirectional pH adjustment cell at the voltage for the determined working duration. 
     In various embodiments, the method further includes: determining, based on optimizing the production rate of desired ions in the unidirectional pH adjustment cell in view of the parameters, a flow rate of water to be supplied to the unidirectional pH adjustment cell; and adjusting the speed of a pump supplying water to the unidirectional pH adjustment cell based on the flow rate. 
     In various embodiments, charging the unidirectional pH adjustment cell for the determined working duration includes providing first voltage of a first polarity to the unidirectional pH adjustment cell and wherein discharging the unidirectional pH adjustment cell for the determined regeneration duration comprises providing second voltage of a second polarity to the unidirectional pH adjustment cell. In various embodiments, optimizing a production rate of desired ions in the unidirectional pH adjustment cell in view of the parameters includes applying at least one of: one or more objective formulas and one or more table values that are representative of optimized production rates. 
     In another aspect, a unidirectional pH adjustment apparatus may include: a unidirectional pH adjustment cell having an input for receiving water, a working electrode and a counter electrode that supply voltage to the water to unidirectionally adjust a pH value of the water, and an output for discharging the water with an adjusted pH value; a power supply supplying a first voltage of a first polarity to the working electrode during a working period of the working electrode; and a controller. The controller may be programmed to: obtain a plurality of parameters related to the unidirectional pH adjustment cell; determine, based on optimizing a production rate of desired ions in the unidirectional pH adjustment cell in view of the parameters, a working duration of the working period of the unidirectional pH adjustment cell and a regeneration duration of a regeneration period of the unidirectional pH adjustment cell; cause the power supply to supply the first voltage of the first polarity to the unidirectional pH adjustment cell for the determined working duration; and cause the power supply to not supply the first voltage of the first polarity to the unidirectional pH adjustment cell for the determined regeneration duration. 
     In various embodiments, the controller is programmed to cause the power supply to supply a second voltage of a second polarity to the unidirectional pH adjustment cell for the determined regeneration duration. In various embodiments, the apparatus may further include one or more sensors each providing one or more of the parameters to the controller. 
     In yet another aspect, a method of controlling regeneration of an electrode in unidirectional pH adjustment of water may include: obtaining a plurality of parameters related to a unidirectional pH adjustment cell, the unidirectional pH adjustment cell including a working electrode and a counter electrode; determining, based on optimizing an energy efficiency of the unidirectional pH adjustment cell in view of the parameters, a regeneration duration of a regeneration period of the unidirectional pH adjustment cell and a working duration of a working period of the unidirectional pH adjustment cell charging the unidirectional pH adjustment cell for the determined working duration and discharging the unidirectional pH adjustment cell for the determined regeneration duration. 
     In yet another aspect, a method of controlling regeneration of an electrode in unidirectional pH adjustment of water may include: obtaining a plurality of parameters related to a unidirectional pH adjustment cell, the unidirectional pH adjustment cell including a working electrode and a counter electrode; determining one or more optimized control parameters for the unidirectional pH adjustment cell based on optimizing at least one of: an energy efficiency of the unidirectional pH adjustment cell in view of the parameters, and a production rate of desired ions in the unidirectional pH adjustment cell; and controlling one or more inputs to the unidirectional pH adjustment cell based on the one or more optimized control parameters. In various embodiments, determining the one or more optimized control parameters for the unidirectional pH adjustment cell may include: determining the one or more optimized control parameters maximize an average production rate of desired ions during charging of the unidirectional pH adjustment cell; and determining the one or more optimized control parameters minimize a production rate of undesired ions during discharging of the unidirectional pH adjustment cell. In various embodiments, the one or more optimized control parameters comprises one or more of: a regeneration duration of a regeneration period; a voltage to be applied by a power source during the regeneration period; a working duration of a working period; a voltage to be applied by the power source during the working period; and a flow rate of water to be supplied to the unidirectional pH adjustment cell. 
     The term “controller” is used herein generally to describe various apparatus relating to the operation of one or more components associated with a UpA cell such as, for example, a power supply for the UpA cell, a pump or other apparatus controlling an amount of water that is supplied to the UpA cell, etc. A controller can be implemented in numerous ways (e.g., such as with dedicated hardware) to perform various functions discussed herein. A “processor” is one example of a controller which employs one or more microprocessors that may be programmed using software (e.g., microcode) to perform various functions discussed herein. A controller may be implemented with or without employing a processor, and also may be implemented as a combination of dedicated hardware to perform some functions and a processor (e.g., one or more programmed microprocessors and associated circuitry) to perform other functions. Examples of controller components that may be employed in various embodiments of the present disclosure include, but are not limited to, conventional microprocessors, application specific integrated circuits (ASICs), and field-programmable gate arrays (FPGAs). 
     In various embodiments, a processor or controller may be associated with one or more storage media (generically referred to herein as “memory”, e.g., volatile and non-volatile computer memory such as RAM, PROM, EPROM, and EEPROM, floppy disks, compact disks, optical disks, magnetic tape, etc.). In some embodiments, the storage media may be encoded with one or more programs that, when executed on one or more processors and/or controllers, perform at least some of the functions discussed herein. Various storage media may be fixed within a processor or controller or may be transportable, such that the one or more programs stored thereon can be loaded into a processor or controller so as to implement various aspects of the present invention discussed herein. The terms “program” or “computer program” are used herein in a generic sense to refer to any type of computer code (e.g., software or microcode) that can be employed to program one or more processors or controllers. 
     It should be appreciated that all combinations of the foregoing concepts and additional concepts discussed in greater detail below (provided such concepts are not mutually inconsistent) are contemplated as being part of the inventive subject matter disclosed herein. In particular, all combinations of claimed subject matter appearing at the end of this disclosure are contemplated as being part of the inventive subject matter disclosed herein. It should also be appreciated that terminology explicitly employed herein that also may appear in any disclosure incorporated by reference should be accorded a meaning most consistent with the particular concepts disclosed herein. 
     These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings, like reference characters generally refer to the same parts throughout the different views. Also, the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. 
         FIG. 1  illustrates an example environment in which regeneration of an electrode in unidirectional pH adjustment of water may be controlled. 
         FIG. 2  illustrates an example of controlling a working period and a regeneration period of a UpA cell and/or controlling a flow rate of water supplied to the UpA cell. 
         FIG. 3  shows a rate of production of desired ions under different sets of working and regeneration durations for parameters. 
         FIG. 4  shows a rate of production of undesired ions under different sets of working and regeneration durations for parameters. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Unidirectional pH adjustment (“UpA”) is a technique for unidirectionally adjusting pH of water during water electrolysis only in one direction. In UpA there are two periods: a “working period” and a “regeneration period.” During the working period a working electrode is in a charging state while a counter electrode is generating ions required for the desired pH change. During the regeneration period, the working electrode is in a discharging state while the counter electrode is generating ions that are undesired for the desired pH change. 
     As described above, during the regeneration period the working electrode is discharging to enable the working electrode to again be charged during the charging state. The regeneration period may be set to occur upon occurrence of a fixed condition, such as when the working electrode is fully charged and/or when the transient voltage drop on the working electrode is close to the decomposing voltage of water. However, this and/or other techniques may suffer from one or more drawbacks. For example, one or more of the techniques may not determine discharging parameters with which the regeneration period is to be performed such as discharging time, a magnitude of reverse voltage applied during the regeneration period, etc. Also, for example, one or more of the techniques may not consider certain measured or otherwise known parameters related to a unidirectional pH adjustment cell to determine a charging status of a working electrode at which regeneration should be performed. Also, for example, one or more of the techniques may not take into account effects on the production rate of desired and/or undesired ions and/or energy efficiency in determining discharging parameters for a regeneration period and/or when the regeneration period should be performed. 
     Thus, applicant has recognized and appreciated that it would be beneficial to provide alternative techniques for controlling regeneration of an electrode in unidirectional pH adjustment of water. For example, applicant has recognized and appreciated that it would be beneficial to monitor one or more measured signals related to a UpA cell, and control when a regeneration period of the UpA cell is started, parameters for the regeneration period, and/or other parameters related to inputs to the UpA cell based on the values. 
       FIG. 1  illustrates an example environment  100  in which regeneration of an electrode in unidirectional pH adjustment of water may be controlled. The example environment  100  includes a pump  122  that supplies water  102 A to a UpA cell  132  via one or more conduits. The water  102 A may be supplied to the pump  122  via, for example, a municipal tap, a tank or other container, etc. The pump  122  may operate continuously or intermittently and may optionally be an adjustable pump that is operable over a range of speeds dependent on control signals received form the controller  140 . In some embodiments, the output of the pump  122  may fluctuate over time due to mechanical wear on the pump  122  and/or other factors. For example, the output of the pump  122  may decrease over time due to mechanical wear of the pump  122 . 
     Interposed between the pump  122  and the UpA cell  132  is a flow meter  124  that measures a quantity of water that is supplied by the pump  122  to the UpA cell  132  and generates signals that indicate the quantity of water. For example, the flow meter  124  may generate signals that indicate a number of gallons or liters per minute (or other flow rate) of water  102 A that is supplied to the UpA cell  132 . The UpA cell  132  includes a housing that houses water  102 A received from the pump  122  and includes a working electrode  136  and a counter electrode  138  disposed in the housing. The working electrode  136  and counter electrode  138  work to unidirectionally adjust the pH of water  102 A housed in the UpA cell. The pH adjusted water  102 B is discharged by the UpA cell  132  to one or more downstream components such as residential or commercial components that discharge or otherwise utilize the pH adjusted water  102 B. In some embodiments, a quantity of water  102 A may be supplied by the pump  122  to the UpA cell  132 , the pH value of that quantity of water may be adjusted by the pH cell  132 , and that quantity of water discharged as pH adjusted water  102 B, and the process may repeat. In some embodiments, water may be continuously supplied by the pump  122  to the UpA cell  132 , adjusted by the UpA cell  132 , and discharged as pH adjusted water  102 B. 
     A power supply  130  is connected to the working electrode  136  of the UpA cell  132  and the counter electrode  138  of the UpA cell  132 . The power supply  130  may be, for example, a DC power supply that is coupled to mains power and converts AC mains power into DC power of a desired magnitude of voltage. As described herein, the power supply  130  supplies DC power during working periods that is of an appropriate polarity to charge the working electrode  136 . As also described herein, the power supply  130  may optionally supply DC power during the regenerations periods that is of an opposite polarity (from the working period polarity) to assist in discharging the working electrode  136 . 
     The example environment  100  also includes a voltmeter  126  that is connected in parallel with the power supply  130  and is in series with the working electrode  136  and the counter electrode  138 . The example environment also includes an ammeter  128  that is connected in series with the working electrode  136 , the counter electrode  138 , and the power supply  130 . The voltmeter  126  measures the voltage of the circuit that includes the working electrode  136 , the counter electrode  138 , and the power supply  130 . The ammeter  128  measures the current of that same circuit and may be, for example, a galvanometer. 
     The example environment  100  also includes a controller  140  that is coupled to the power supply  130  and controls when and/or how the power supply  130  supplies DC power to charge the working electrode  136 , when and/or how the power supply  130  supplies DC power to discharge the working electrode  136 , and/or when (if ever) the power supply  130  doesn&#39;t supply any DC power to the working electrode  136 . For example, the controller  140  may control when the power supply  130  supplies DC power to charge the working electrode  136  during the working period (e.g., only after completion of a preceding regeneration period). Also, for example, the controller  140  may control a working duration of time that the power supply  130  supplies DC power to charge the working electrode  136  during a working period based on a determined optimized charging time. Also, for example, the controller  140  may control a voltage of the DC power supplied by the power supply  130  to charge the working electrode  136  during the working period based on a determined optimized charging voltage. Also, for example, the controller  140  may control a regeneration duration of time that the power supply  130  supplies DC power to discharge the working electrode  136  during a regeneration period based on a determined optimized discharging time. Also, for example, the controller  140  may control a voltage of the DC power supplied by the power supply  130  to discharge the working electrode  136  during the regeneration period based on a determined optimized discharging voltage 
     As described herein, during working periods, the working electrode  136  is in a charging state while the counter electrode  138  is generating ions required for the desired pH change. For example, where UpA is applied to decrease the pH of water, the counter electrode  138  produces required H+ ions during the working periods. On the other hand, where UpA is applied to increase the pH of water, the counter electrode  138  produces required OH− ions during the working periods. During the regeneration periods, the working electrode  136  is in a discharging state while the counter electrode  138  is generating ions that are undesired for the desired pH change. For example, where UpA is applied to decrease the pH of water, the counter electrode  138  produces undesired OH− ions during the regeneration periods. On the other hand, where UpA is applied to increase the pH of water, the counter electrode  138  produces undesired H+ ions during the regeneration periods. 
     The controller  140  includes a parameter optimization module  142  and a control module  144 . Generally, the parameter optimization module  142  identifies a plurality of measured or otherwise known parameters indicative of states of various components related to the operation of the UpA cell  132  and determines one or more parameters related to inputs to the UpA cell based on the values. For example, the parameter optimization module  142  may obtain measured values from voltmeter  126 , ammeter  128 , and/or flow meter  124  and optionally additional parameters such as a time constant of the working electrode  136  and/or a capacitance of a capacitor of the working electrode  136 . The additional parameters may be, for example, stored in memory associated with the controller  140  based on input during manufacture and/or input from a consumer via one or more user interface elements. The parameter optimization module  142  may utilize the measured or otherwise known parameters to determine optimized parameters for: a flow rate of water to the UpA cell  132 , a regeneration duration for the UpA cell  132 , a working duration for the UpA cell  132 , a voltage to be provided during the regeneration period for the UpA cell  132 , and/or a voltage to be provided during the working period for the UpA cell  132 . 
     In some embodiments, the parameter optimization module  142  may determine the parameters related to inputs to the UpA cell  132  based on optimizing the total desired and/or undesired ions production rate and/or energy efficiency of the UpA cell  132  in view of the measured or otherwise known parameters. In some of those embodiments, the parameter optimization module  142  determines the parameters based on one or more formulae and/or table values that indicate those parameters will optimize (according to the formulae and/or table values) a production rate of desired ions in the UpA cell  132  and/or optimize (again, according to the formulae and/or table values) energy efficiency of the UpA cell  132 , in view of the measured or otherwise known parameters. In some embodiments, optimizing a production rate and/or other value doesn&#39;t necessarily mean that it is absolutely the most optimal—rather that it is the most optimal in view of applied formulae and/or table values and in view of the measured or otherwise known parameters utilized in the applied formulae and/or table values. 
     As one example, assume the following parameters: an applied voltage supplied by power supply  130  during a working period (ε), an applied voltage supplied by power supply  130  during a working period (ε′), a charging time constant of the working electrode  136  (τ), a regenerating time constant of the working electrode  136  (τ′), a capacitance of the working electrode  136  (C), and a flow rate of water supplied to the UpA cell  132  (F). These values may be “known” based on, for example, signals received from voltmeter  126  and/or ammeter  128 , the values being stored in non-volatile memory, and/or the values being inputted via one or more users via a user interface. Further assume V AC0  represents the voltage drop on the working electrode  136  at the time moment of starting charging (i.e., the start of the working period) of the working electrode  136  and V ACE  represents the voltage drop on the working electrode  136  at the time moment of starting discharging (i.e., the start of the regeneration period) of the working electrode  136 . The parameter optimization module  142  may determine values for V AC0  and V ACE  that minimize the objective function: r 1 =C*(V ACE −V AC0 )/(F*τ)/ln [(ε−V AC0 )/(ε−V ACE )] and maximize the objective function: r 2 =C*(V ACE −V AC0 )/(F*τ′)/ln [(ε′−V ACE )/(ε′−V AC0 )]. The parameter optimization module  142  may further utilize the determined values for V AC0  and V ACE  to determine an optimized working duration and an optimized regeneration duration based on the following formulas: 
       working duration=τ*ln [(ε− V   AC0 )/(ε− V   ACE )]
 
       regeneration duration=τ′*ln [( V   ACE +ε′)/( V   AC0 +ε′)]
 
     Generally, the control module  144  utilizes one or more of the optimized parameters determined by the parameter optimization module  142  to control one or more inputs related to the UpA cell  132 . For example, the control module  144  may control when and/or how power is provided by power supply  130  to effectuate determined optimized parameters. For instance, where the optimized parameters include a working duration and a regeneration duration, the control module  144  may direct the power supply  130  to supply a first voltage of a first polarity for the working duration and to supply a second voltage of a second polarity form the regeneration duration. Also, for example, where the optimized parameters include a voltage of the power supply  130  for the working period and/or a voltage of the power supply  130  for the regeneration period, the control module  144  may direct the power supply  130  to supply the respective voltages during the respective periods. Also, for example, where the optimized parameters include a flow rate of water during the working period and/or regeneration period, the control module  144  may adjust the speed of pump  122  to achieve such flow rate (optionally taking into account feedback from the flow meter  124 ). 
     One example of determining optimized parameters for inputs to the UpA cell  132  based on measure or otherwise known parameters is provided below with reference to formulas (1) through (9). Assume that the voltage drop on the working electrode  136  is V AC0  at the time moment of starting charging (i.e., the start of the working period) of the working electrode  136  and V ACE  at the time moment of starting discharging (i.e., the start of the regeneration period) of the working electrode  136 , respectively. In other words, the charging of the working electrode  136  is stopped (i.e., the stop of the working period) and discharging is started (i.e., the start of the regeneration period) when the voltage drop on the working electrode  136  increases to V ACE , and the discharging is stopped (i.e., the stop of the regeneration period) when the voltage drop on the working electrode  136  decreases to V AC0 . The control module  144  may start and/or stop the working period and regeneration period by sending appropriate signals to power supply  130  to, for example, cause power supply  130  to supply DC voltage of an appropriate polarity. In some embodiments, the control module  144  may determine when to start and/or stop working and regeneration periods based on previously determined working and regenerations durations. For example, the control module  144  may cause a working period to be performed, followed by a regeneration period, followed by another working period, another regeneration period, etc. In some embodiments, the control module  144  may utilize default settings for determining when to start and/or stop working and regeneration periods such as, for example, when the controller  140  is reset and/or first installed. 
     The transient voltage drop on working electrode  136  (Vw) during a working period can be expressed a function of: the applied voltage supplied by power supply  130  during the working period (ε), the duration of the working period/charging time (t W ), the charging time constant of the working electrode  136  (τ), and the voltage drop of the working electrode  136  at the start of the working period (V AC0 ). The charging time constant (τ) of the working electrode  136  is the time required to charge the capacitor of working electrode  136 , through the resistor of the working electrode  136 , by approximately 63.2 percent of the difference between the initial value and final value. 
     The transient voltage drop on working electrode  136  (V w ) during a working period can be expressed mathematically as: 
         V   W   =f (ε,τ, V   AC0 )  (1)
 
     The generating rate of desired ions (r W ) (either H+ or OH−, depending on the embodiment) at time (t) during the working period is determined by the time t and a current I w , which can be expressed mathematically as: 
         r   W   =f ( t,I   W )  (2)
 
     Current I W  can be expressed mathematically as: 
         I   W   =C *( dV   W   /dt ),  (3)
 
     where C is the capacitance of the working electrode  136 . 
     During the regeneration period, usually an inverse power supply is employed. For example, the polarity of the power supply  130  could be inverted (and optionally the voltage altered) and/or the power supply  130  may include a first power supply for use in the working period and a second power supply for use in the regeneration period. During the regeneration period, the transient voltage drop on the working electrode  136  (V R ) is the function of the total inverse voltage supplied during the regeneration period (ε′), the duration of the regeneration period/discharging time (t R ), the discharging time constant of the working electrode  136  (τ′), and the voltage drop of the working electrode  136  at the start of the regeneration period (V ACE ). 
     The transient voltage drop on working electrode  136  (V w ) during a regeneration period can be expressed mathematically as: 
         V   R   =f (ε′, t,τ′,V   ACE )  (4)
 
     The generating rate of desired ions (r W ) (either H+ or OH − , depending on the embodiment) at time (t) during the regeneration period is determined by the time t and a current I R , which can be expressed mathematically as: 
         r   R   =f ( t,I   R )  (5)
 
     Current I R  can be expressed mathematically as: 
         I   R   =C *( dV   R   /dt ),  (6)
 
     where C is the capacitance of the working electrode  136 . 
     In embodiments where the controller  140  determine states of one or more variables related to the control of the UpA cell  132  based on optimizing the total production rate and/or production efficiency of the UpA cell  132 , the parameter optimization module  142  may seek to determine a working period duration and/or regeneration period duration that maximizes the total production of desired ions, minimizes the total production of undesired ions, and/or maximizes energy efficiency. 
     An average production rate of desired ions (r 1 ) over a working period (t W ) can be expressed mathematically as: 
         r   1 =∫ 0   tW   rWdt/t   W   (7)
 
     An average production rate of undesired ions (r 2 ) over a regeneration period (t R ) can be expressed mathematically as: 
         r   2 =∫ 0   R   rRdt/t   R   (8)
 
     Energy efficiency (E ff ) can expressed mathematically as: 
         E   ff   =ΔH*rW /( I   w   2   *R+I   R   2   *R ′),  (9)
 
     where:
         ΔH=reaction heat needed for generating per molar desired ion, J/mol;   R=total electrical resistance of the circuit during working period, Ω;   R′=total electrical resistance of the circuit during regeneration period, Ω.       

     The parameter optimization module  142  may determine optimized parameters for a working and regeneration period based on formulas (7), (8), and/or (9) above. For example, the parameter optimization module  142  could determine a working duration of a working period and a regeneration duration of a regeneration period that maximize and minimize respective of the values of r 1  and r 2  and/or that maximize the value of E ff . The control module  144  may utilize the determined optimized parameters to control the power supply  130  and/or other components. 
     Another example of determining optimized parameters for inputs to the UpA cell  132  based on measure or otherwise known parameters is provided below with reference to formulas (10) through (20). 
     The transient voltage drop on working electrode  136  (Vw) during a working period can be expressed mathematically as: 
         V   W =(ε− V   AC0 )*(1−exp(− t /τ))+ V   AC0   (10)
 
     Current during the working period (I) can be expressed mathematically as: 
         I   W   =C *( dV   W   /dt ) or  I   W   =C *(ε− V   AC0 )/τ*exp(− t /τ)  (11)
 
     The transient generating rate of desired ions (r W ) (either H+ or OH − , depending on the embodiment) at time (t) during the working period can be expressed mathematically as: 
         r   W   =I   W   /F,   (12)
 
     where F is the flow rate of water being supplied to the UpA cell (e.g., as indicated by flow meter  124 ). 
     The time needed for the voltage drop on the working electrode  136  to reach V ACE  can be calculated based on equation (10), and can be expressed mathematically as: 
         t   W =τ*ln [(ε− V   AC0 )/(ε− V   ACE )]  (13)
 
     During a regeneration period, the total inverse voltage is c′, the initial voltage drop on the working electrode  136  is V ACE , and the transient voltage drop on the working electrode  136  during the regeneration period is V R . The relationship between these values can be expressed mathematically as: 
     (14) 
     
       
         
           
             
               
                 
                   V 
                   R 
                 
                 + 
                 
                   ɛ 
                   ′ 
                 
               
               = 
               
                 
                   
                     I 
                     R 
                   
                   * 
                   
                     R 
                     ′ 
                   
                 
                 = 
                 
                   
                     R 
                     ′ 
                   
                   * 
                   C 
                   * 
                   
                     ( 
                     
                       
                         dV 
                         R 
                       
                       dt 
                     
                     ) 
                   
                 
               
             
             , 
           
         
       
     
     where R′ is the resistance of the circuit during the regeneration period and C is the capacitance of the working electrode  136 . 
     Integrating equation (14) produces: 
         V   R =( V   ACE +ε′)*exp(− t /τ′)−ε′  (15)
 
     The time needed for the voltage drop on the working electrode  136  to decrease to V AC0  (t R /the regeneration duration) during the regeneration period can be expressed mathematically as: 
         t   R =τ′ ln [( V   ACE +ε′)/( V   AC0 +ε′)]  (16)
 
     Current (I R ) during the regeneration period can be expressed mathematically as: 
         I   R   =−C *( dV   R   /dt )= C *(ε′+ V   ACE )/τ′*exp(− t /τ′)  (17)
 
     The transient generating rate of undesired ions (r r ) (either H+ or OH − , depending on the embodiment) at time (t) during the regeneration period can be expressed mathematically as: 
         r   R   =I   R   /F,   (18)
 
     where F equals the flow rate of water into the UpA cell  132  (e.g., as measured by flow meter  124   
     From equations (7) and (8), the average production rate of desired ions (r 1 ) and undesired ions (r 2 ) during the working period and the regeneration periods can be expressed mathematically as: 
         r   1   =C *( V   ACE   −V   AC0 )/( F *τ)/ln [(ε− V   AC0 )/(ε− V   ACE )]  (19)
 
         r   2   =C *( V   ACE   −V   AC0 )/( F *τ′)/ln [(ε′+ V   ACE )/(ε′+ V   AC0 )]  (20)
 
     The parameter optimization module  142  may determine optimized parameters for a working and regeneration period based on formulas (19) and (20) above. For example, the parameter optimization module  142  could determine values of V AC0  and V ACE  that maximize and minimize respective of the values of r 1  and r 2 . Meaningful ranges of V AC0  and V ACE  may be set to constrain the optimization process and/or for other considerations such as to account for known limits of the working electrode  136 . The parameter optimization module  142  may further utilize the determined values for V AC0  and V ACE  to determine an optimized working duration and an optimized regeneration duration based on formulas (13) and (16). The control module  144  may utilize the determined optimized parameters to control the power supply  130  and/or other components. 
       FIGS. 3 and 4  show the values of r 1  ( FIG. 3 ) and r 2  ( FIG. 4 ) under different sets of working and regeneration durations for parameters of ε=2 V, ε′=0.7 V, C=10 F, τ=30 s, and τ′=25 s. The assumed V ACE  range is 0.5-1.3 V and assumed V AC0  range is 0.1-0.4 V. The t W  axis in each of the figures represents the working period duration (in seconds) and the t R  axis in each of the figures represents the regeneration period duration (in seconds). The z-axis in each of the figures represents the rate of ion production (in mols per second). Based on formulas (19) and (20), the parameter optimization module  142  may determine that both the maximum value for r 1  and minimum value for r 2  are reached when the values of V AC0  and V ACE  are the smallest values in the corresponding meaningful ranges and the corresponding durations for working and regeneration periods are 7.1 s and 10.1 s, respectively. More parameters could be also optimized through the similar approach. For example, if the total inverse voltage (ε′) is changed from 0.7 V to 2.7 V, the corresponding optimized duration for regeneration becomes 3.3 s instead of 10.1 s. 
     In some embodiments of the example environment  100 , one or more of the components may be included together as part of a UpA apparatus. For example, in some embodiments the UpA cell  132 , the controller  140 , the pump  122 , the flow meter  124 , the power supply  130 , the voltmeter  126 , and the ammeter  128  may be packaged in a common housing and/or multiple housing that are electrically and/or mechanically coupled to one another. The UpA apparatus may include connections to, for example, connect an input of the UpA apparatus to the water  102 A and optionally to connect an output of the UpA apparatus (that outputs pH adjusted water  102 B) to one or more downstream components. In some of those embodiments the connections may be pipe couplings. 
       FIG. 2  illustrates an example of controlling a working period and a regeneration period of a UpA cell  132  and/or controlling a flow rate of water supplied to the UpA cell  132 . The parameter optimization module  142  identifies a plurality of measured or otherwise known parameters indicative of states of various components related to the operation of the UpA cell  132 . For example, one or more of the values may be measured values received by the parameter optimization module  142  from one or more of the flow meter  124 , the voltmeter  126 , and the ammeter  128 . Also, for example, one or more of the values may be retrieved from non-volatile memory associated with the parameter optimization module  142  or programmed in the parameter optimization module  142 , such as a time constant of the working electrode  136  and/or a capacitance of a capacitor of the working electrode  136 . 
     The parameter optimization module  142  utilizes the measured or otherwise known parameters to determine optimized parameters related to inputs to the UpA cell such as, for example, one or more of: a flow rate of water to the UpA cell  132 , a regeneration duration for the UpA cell  132 , a working duration for the UpA cell  132 , a voltage to be provided during the regeneration period for the UpA cell  132 , and/or a voltage to be provided during the working period for the UpA cell  132 . In some embodiments, the parameter optimization module  142  may determine the optimized parameters based on optimizing the total desired and/or undesired ions production rate and/or energy efficiency of the UpA cell  132  in view of the measured or otherwise known parameters. In some of those embodiments, the parameter optimization module  142  determines the parameters based on one or more formulae and/or table values that indicate those parameters will optimize a production rate of desired ions in the UpA cell  132  and/or optimize energy efficiency of the UpA cell  132 , in view of the measured or otherwise known parameters. 
     The optimized parameters determined by the parameter optimization module  142  are provided to the control module  144 . Generally, the control module  144  utilizes one or more of the optimized parameters to control one or more inputs related to the UpA cell  132 . For example, as illustrated in  FIG. 2 , the control module  144  may control a working period and a regeneration period of the UpA cell based on the optimized parameters by providing signals to the power supply  130  that control when and/or how power is provided to the UpA cell  132  by power supply  130 . The power supply  130  provides power to the UpA cell  132  based on the control signals received from the control module  144 . For instance, where the optimized parameters include a working duration and a regeneration duration, the control module  144  may direct the power supply  130  to supply a first voltage of a first polarity for the working duration and to supply a second voltage of a second polarity form the regeneration duration. Also, for example, where the optimized parameters include a voltage of the power supply  130  for the working period and/or a voltage of the power supply  130  for the regeneration period, the control module  144  may direct the power supply  130  to supply the respective voltages during the respective periods. 
     As another example, where the optimized parameters include a flow rate of water during the working period and/or regeneration period, as illustrated in  FIG. 2  the control module  144  may provide signals to the pump  122  to achieve that flow rate of water from the pump  122 . The pump  122  provides water to the UpA cell  132  based on the control signals received from the control module  144 . For instance, the parameter optimization module  142  may have determined an optimized parameter for a flow rate based on determining a value for “F” (within a meaningful range of F) in formulas (19) and (20) above that maximize and minimize respective of the values of r 1  and r 2  (while optionally maximizing/minimizing those values in view of other values that can be adjusted such as V ACE , V AC0 , ε, ε′). The control module  144  may utilize the value of F to control the pump  122 . 
     An example of method of controlling one or more inputs to a UpA cell based on control parameters determined based on optimizing a production rate of desired ions and/or energy efficiency can be described as follows. 
     In a first step, a plurality of parameters related to an UpA cell are identified. For example, the parameter optimization module  142  may receive one or more measured values from one or more of the flow meter  124 , the voltmeter  126 , and the ammeter  128 . Also, for example, one or more of the values may be retrieved from non-volatile memory associated with the parameter optimization module  142 , programmed in the parameter optimization module  142 , and/or received from user input at a user interface element. 
     In a second step, one or more control parameters for the UpA cell are determined based on optimizing a production rate of desired ions and/or energy efficiency in view of the parameters. For example, the parameter optimization module  142  may determine the optimized parameters based on optimizing the total desired and/or undesired ions production rate and/or energy efficiency of the UpA cell  132  in view of the measured or otherwise known parameters. In some of those embodiments, the parameter optimization module  142  determines the parameters based on one or more formulae and/or table values that indicate those parameters will optimize a production rate of desired ions in the UpA cell  132  and/or optimize energy efficiency of the UpA cell  132 , in view of the measured or otherwise known parameters. For instance, the parameter optimization module  142  may utilize one or more of formulas (7), (8), (9), (19), and (20). 
     In a third step, one or more inputs to the UpA cell are controlled based on the determined control parameters. For example, the control module  144  may utilize one or more of the optimized parameters to control one or more inputs related to the UpA cell  132 . For instance, the control module  144  may control a working period and a regeneration period of the UpA cell  132  based on the optimized parameters by providing signals to the power supply  130  that control when and/or how power is provided to the UpA cell  132  by power supply  130 . Also, for instance, where the optimized parameters include a flow rate of water during the working period and/or regeneration period, the control module  144  may provide signals to the pump  122  to achieve that flow rate of water from the pump  122 . 
     The one or more inputs to the UpA cell may continue to be controlled. In some embodiments, the first and second steps may be repeated to determine new control parameters and the one or more inputs to the UpA cell controlled based on the new control parameters. For example, the controller  140  may periodically or continuously perform all 3 steps. Also, for example, the controller  140  may perform the first and second steps upon detection of a change in one or more measured values such as changes indicated by received signals from flow meter  124 , voltmeter  126 , and/or ammeter  128 . 
     It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word “comprising” does not exclude the presence of elements or steps other than those listed in a claim. The word “a” or “an” preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and/or by means of a suitably programmed processor. In the device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.