PH CONTROL METHOD FOR UPA CELL

Abstract

The present invention relates to a device and method for controlling the pH of a UpA cell. The device comprises a receiving unit for receiving a preset parameter including a desired pH value; a computing module configured to calculate an UpA cell parameter based on the preset parameter; and a control module configured to control the UpA cell based on the calculated UpA cell parameter.

Claims

1. Device for controlling the pH of an unidirectional pH adjustment cell, comprising: the unidirection pH adjustment cell; a receiving unit for receiving a preset parameter including a desired pH value; a computing module configured to calculate an unidirectional pH adjustment cell parameter based on the preset parameter including the desired pH value; and a control module configured to control the unidirectional pH adjustment cell based on the calculated unidirectional pH adjustment cell parameter.

2. Device according to claim 1, wherein the receiving unit further receives at least one preset parameter selected from the group consisting of an initial pH value, a flow dynamic of feed water, and a flow dynamic of generated water, a thickness of reaction layer, electrochemical reaction rate, diffusion index, a thickness of diffusion layer, a water volume, and a diffusion cross area.

3. Device according to claim 1, wherein the preset parameter comprises at least a thickness of reaction layer, electrochemical reaction rate, diffusion index, a thickness of diffusion layer, a water volume, and a diffusion cross area.

4. Device according to claim 3, wherein the computing module is further configured to calculate the unidirectional pH adjustment cell parameter based on equations (4) to (7):
d*(dC.sub.s/dt)=r−D*(C.sub.s−C.sub.b)/L  (4),
r=I/F  (5),
V*(dC.sub.b/dt)=D*A*(C.sub.s−C.sub.b)/L  (6), wherein d is thickness of reaction layer, C.sub.s is concentration of OH.sup.− in the reaction layer, t is time, I is current, F is Faraday constant, D is diffusion index, C.sub.b is concentration of OH.sup.− in the bulk water, L is thickness of diffusion layer (L), V is water volume, A is diffusion cross area; and
C.sub.s0=C.sub.b0=10.sup.pH0−14*1000  (7), wherein C.sub.s0 is initial concentration of OH.sup.− in the reaction layer, C.sub.b0 is initial concentration of OH.sup.− in water, and pH0 is the initial pH value of water.

5. Device according to claim 1, wherein the unidirectional pH adjustment cell has a power source.

6. Device according to claim 5, wherein the pH adjustment cell does not comprise a pH sensor.

7. Device according to claim 1, further comprising a flowmeter for controlling flow of water provided to the unidirectional pH adjustment cell.

8. Device according to claim 1, further comprising a user interface for inputting the preset parameter and the unidirectional pH adjustment cell parameter.

9. Method for controlling the pH of an unidirectional pH adjustment cell, comprising: providing the unidirectional pH adjustment cell; receiving a preset parameter including a desired pH value; calculating an unidirectional pH adjustment cell parameter based on the preset parameter; controlling the unidirectional pH adjustment cell based on the calculated unidirectional pH adjustment cell parameter.

10. Method according to claim 9, wherein the at least one preset parameter is selected from the group consisting of an initial pH value, a flow dynamic of feed water, and a flow dynamic of generated water, a thickness of reaction layer, electrochemical reaction rate, diffusion index, a thickness of diffusion layer, a water volume, a diffusion cross area.

11. Method according to claim 9, wherein the preset parameter comprises at least a thickness of reaction layer, electrochemical reaction rate, diffusion index, a thickness of diffusion layer, a water volume, and a diffusion cross area.

12. Method according to claim 11, wherein calculating the unidirectional pH adjustment cell parameter is based on equations (4) to (7):
d*(dC.sub.s/dt)=r−D*(C.sub.s−C.sub.b)/L  (4),
r=I/F  (5),
V*(dC.sub.b/dt)=D*A*(C.sub.sC.sub.b)/L  (6), wherein d is thickness of reaction layer, C.sub.s is concentration of OH.sup.− in the reaction layer, t is time, I is current, F is the Faraday constant, D is diffusion index, C.sub.b is concentration of OH.sup.− in the bulk water, L is thickness of diffusion layer (L), V is water volume, A is diffusion cross area; and
C.sub.s0=C.sub.b0=10.sup.pH0−14*1000  (7), wherein C.sub.s0 is initial concentration of OH.sup.− in the reaction layer, C.sub.b0 is initial concentration of OH.sup.− in water, and pH0 is the initial pH value of water.

13. Method according to claim 9, further comprising controlling flow of water provided to the unidirectional pH adjustment cell.

14. Method according to claim 10, further comprising inputting the preset parameter and the unidirectional pH adjustment cell parameter.

15. Computer program comprising program code means for causing a computer to carry out the steps of the method as claimed in claim 9 when said computer program is carried out on the computer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0057] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter. In the following drawings

[0058] FIG. 1 shows a lateral view of an UpA cell for use with the present device;

[0059] FIG. 2 schematically shows the main features of a device for controlling the pH of an UpA cell according to the invention;

[0060] FIG. 3 schematically shows employing the present method; and

[0061] FIG. 4 shows the development of the pH value of bulk water independence of different initial pH values.

DETAILED DESCRIPTION OF THE INVENTION

[0062] FIG. 1 shows a lateral view of an UpA cell 40. The UpA cell 40 has a rectangular or square base area. Working electrode 50 and counter electrode 52 are arranged on opposite walls of the UpA cell facing each other. Alternatively, the working electrode 50 and counter electrode 52 may be side walls of the UpA cell or form an integral part thereof. Diffusion layer 56 is arranged parallel to the working electrode 50 and counter electrode 52 sharing the vessel volume in a large volume, the water bulk volume 54, and a small volume, the volume within the reaction layer 58. Thickness of reaction layer 58 is indicated by d and thickness of diffusion layer by L.

[0063] FIG. 2 schematically shows a device 10 for controlling the pH of an UpA cell 40 according to the present invention. A receiving unit 12 receives preset parameters 20, 30 including a desired pH value 22, and other water related parameters, such as an initial pH value 20a, a flow dynamic of feed water 20b, and a flow dynamic of generated water. In addition, the receiving unit receives several preset parameters 30 characterizing the UpA cell 40 including the thickness of the reaction layer 30a, electrochemical reaction rate 30b, diffusion index 30c, thickness of diffusion layer 30d, a water volume 30e which is the water bulk volume, and a diffusion cross area. The preset parameters 20, 30, water related parameters and parameters characterizing the UpA cell, are in this example manually inputted by user interface 18 and permanently stored in a storage unit (not shown).

[0064] Computing module 14 is configured to calculate UpA cell parameters 32, 34 based on the preset parameters 20, 30. Further values which are required may be preset. Such values include for instance the Faraday constant which is not shown. UpA cell parameter 32 is according to this example the operating time of the UpA cell and UpA cell parameter 34 is the current employed. It will be appreciated that usually one of both parameters is also preset, for instance current which may be preset according to requirements of the national power supply. Alternatively operating time may be preset, such as one minute or more, preferably two minutes, three minutes, four minutes, five minutes, or ten minutes. In case both UpA cell parameters 32, 34 are not preset, the device 10 may choose a random value for either operating time or current and calculate the other parameter. Such random values are within acceptable ranges, for instance the examples given for a preset operating time. Alternatively, the device may employ a high current at the beginning which decreases with time.

[0065] Control unit 16 is configured to control the UpA cell and the power source 42 thereof based on a calculated UpA cell parameter 30. Said calculated UpA cell parameter 30 includes in a present case operating time 32 and a power supply parameter 34, which is in the present case the current. Due to inversely proportional relationship between operating time and current required for operating UpA cell. In FIG. 2 both possibilities, i.e. calculating of operating time 32 based on known power supply parameters 34 and calculating power supply parameter 34 based on known operating time, such as preset operating time, are shown. Control module 16 therefore affects required adjustments with UpA cell 40 having power source 42. In addition, control module 16 controls flowmeter 44 to provide a predetermined amount of water with predetermined flow parameters to UpA cell 40.

[0066] FIG. 3 schematically shows performing of the method according to the present invention. Feed water 62 is provided to flowmeter 44 which in turn provides a predetermined amount of water to UpA cell 40. Depending on the amount of water having the desired pH within the UpA cell generated water is discharged. Feed water is initially subjected to measuring the pH value by an indicator test paper (60). This value is received by the receiving unit 12 of device 10, and subjected to calculating/computing in computing module 12. All other required preset parameters 20, 30 including parameters 32 and/or 34 are prestored in device 10. Accordingly, control module 16 may readily control the UpA cell 40 and flowmeter 44 based on the prestored values.

[0067] FIG. 4 shows development of pH value for bulk water for different initial pH values. The above mentioned UpA cell 40 is used for generating alkaline water. As indicated above, the concentrations of generated hydroxide ion may be predicted on the pre-established model with equations (4)-(7). FIG. 4 shows a simulation of hydroxide evolution and the influences of initial pH values on feed water, which is in this example tap water. Tap water has initial pH 6.5, 7.5, 8.5 indicated by reference numbers 76, 78, and 80. Axis 70 shows operating time in seconds and axis 72 development of pH value in the water bulk. The desired pH value is 10.5 (indicated by 74) and the volume the UpA cell 40 amounts to 1 l. The current is set to 1 A, thickness (d) of the reaction layer 58 is 10.sup.−7 m; diffusion index is 5*10.sup.−8 m.sup.2/s, thickness (L) of the diffusion layer 56 is 10.sup.−5 m, Faraday constant is 96485 C/mol, diffusion cross area is 0.1 m.sup.2, and total volume of water bulk amounts, as indicated above, 10.sup.−3 /m.sup.3.

[0068] It may be derived from FIG. 4 that variation of initial pH of water between the range of 6.5-8.5, which is usually for tap water, has a neglectable influence on the operating time needed for generation of 1 l qualified alkaline water of pH 10.5 (around 300 s), which indicates that measuring pH by pH indicator paper is accurate enough for use. Accordingly, the initial pH value is not critical and maybe either preset or measured in longer time intervals, such as one week or longer, preferably, two weeks, three weeks, one month, two months, three months or six months.

[0069] In conclusion, the device, and method presented herein reliably controls the pH value of an UpA cell. As an advantage, the use of sensors for determining/measuring pH value of generated water may be omitted rendering the device cost-efficient and less prone to technical failure. Another advantage is that lifetime of the working electrode is elongated and that maintenance of the working electrode is facilitated.

[0070] While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims.

[0071] In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. A single element or other unit may fulfill the functions of several items recited in the claims. 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.

[0072] A computer program may be stored/distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems.

[0073] Any reference signs in the claims should not be construed as limiting the scope.