Electrolytic tank bipolar plate and zero-spacing non-polar frame alkaline water hydrogen production electrolytic tank

Abstract

The utility model provides an electrolytic bath bipolar plate and a zero-spacing non-polar frame alkaline water hydrogen production electrolytic bath, and relates to the technical field of electrolytic equipment. The bipolar plate comprises a polar plate body, a cathode flow field area and an anode flow field area, the cathode flow field area is arranged on the cathode side of the pole plate body, and the anode flow field area is arranged on the anode side of the pole plate body; the cathode water-drop-shaped flow fields and the anode water-drop-shaped flow fields are arranged in the cathode flow field area at equal intervals and are in contact with cathode electrodes in the electrolytic cell, and the anode water-drop-shaped flow fields are arranged in the anode water-drop-shaped flow fields at equal intervals and are in contact with anode electrodes in the electrolytic cell. The contact area can be effectively increased, so that the contact resistance is reduced, the electric energy loss is reduced, and the temperature of the electrolytic bath is more uniform.

Description

TECHNICAL FIELD

[0001] The utility model relates to electrolytic equipment technical field especially is related to a kind of bipolar plate and zero spacing electrode frame alkali water hydrogen production electrolytic cell of electrolytic cell. BACKGROUND

[0002] The existing alkali water electrolytic cell is mainly composed of an electrolytic cell, an electrolytic cell, a nickel mesh, a diaphragm and a sealing ring. The electrolytic cell is composed of a plurality of electrolytic cells connected in series. A 30% potassium hydroxide solution is used as the electrolyte, and the working temperature is 85-95°C. The nickel mesh is placed on both sides of the diaphragm as an electrode, and is placed between the two polar plates. The two polar plates are sealed by a sealing ring. The surface area of the nickel mesh electrode is limited, and it is difficult to increase the reaction area. Moreover, the contact area between the nickel mesh and the diaphragm is small, and the current density is small, resulting in large contact resistance and large ohmic loss.

[0003] Therefore, there is an urgent need for an electrolytic cell bipolar plate and zero-spacing electrode frame alkali water hydrogen production electrolytic cell that can effectively increase the contact area and reduce the contact resistance and power loss. SUMMARY

[0004] The utility model discloses a kind of bipolar plate and zero-spacing electrode frame alkali water hydrogen production electrolytic cell of electrolytic cell, solve the technical problem that the contact resistance in prior art is large, easy to produce large ohmic loss. The preferred technical solutions in many technical solutions provided by the utility model can produce many technical effects, which are described in detail below.

[0005] To achieve the above-mentioned purpose, the utility model provides the following technical solutions:

[0006] The utility model provides a kind of bipolar plate of electrolytic cell, comprising:

[0007] polar plate body;

[0008] cathode flow field area and anode flow field area, the cathode flow field area is arranged on the cathode side of the polar plate body, and the anode flow field area is arranged on the anode side of the polar plate body;

[0009] cathode water drop type flow field and anode water drop type flow field, a plurality of cathode water drop type flow fields are arranged equidistantly in the cathode flow field area and are in contact with the cathode electrode in the electrolytic cell, and a plurality of anode water drop type flow fields are arranged equidistantly in the anode water drop type flow field and are in contact with the anode electrode in the electrolytic cell.

[0010] Preferably, it further comprises:

[0011] liquid inlet channel, a plurality of liquid inlet channels are arranged at the first end of the polar plate body and are in communication with the cathode flow field area and the anode flow field area respectively;

[0012] gas-liquid passages, the gas-liquid passages being formed in the second end of the polar plate body and respectively communicating with the cathode flow field region and the anode flow field region.

[0013] Preferably, the liquid inlet passage comprises:

[0014] cathode alkali liquid inlet main flow passages, the cathode alkali liquid inlet main flow passages being formed in the first end of the polar plate body and communicating with the cathode flow field region;

[0015] anode alkali liquid inlet main flow passages, the anode alkali liquid inlet main flow passages being formed in the first end of the polar plate body and communicating with the anode flow field region.

[0016] Preferably, the liquid inlet passage further comprises:

[0017] cathode alkali liquid inlet flow field passages, the cathode alkali liquid inlet flow field passages being formed in the first end of the polar plate body and communicating between the cathode alkali liquid inlet main flow passages and the cathode flow field region;

[0018] anode alkali liquid inlet flow field passages, the anode alkali liquid inlet flow field passages being formed in the first end of the polar plate body and communicating between the anode alkali liquid inlet main flow passages and the anode flow field region.

[0019] Preferably, the gas-liquid passage comprises:

[0020] cathode alkali liquid hydrogen outlet main passages, the cathode alkali liquid hydrogen outlet main passages being formed in the second end of the polar plate body and communicating with the cathode flow field region;

[0021] anode alkali liquid hydrogen outlet main passages, the anode alkali liquid hydrogen outlet main passages being formed in the second end of the polar plate body and communicating with the anode flow field region.

[0022] Preferably, the gas-liquid passage comprises:

[0023] cathode alkali liquid hydrogen outlet flow field passages, the cathode alkali liquid hydrogen outlet flow field passages being formed in the second end of the polar plate body and communicating between the cathode alkali liquid hydrogen outlet main passages and the cathode flow field region;

[0024] anode alkali liquid hydrogen outlet flow field passages, the anode alkali liquid hydrogen outlet flow field passages being formed in the second end of the polar plate body and communicating between the anode alkali liquid hydrogen outlet main passages and the anode flow field region.

[0025] A zero-spacing non-polar frame alkaline water hydrogen production electrolytic cell, comprising the electrolytic cell bipolar plate, further comprising a cathode electrode, a diaphragm, an anode electrode, a rear end current collector plate, a rear end insulating plate and a rear end plate installed in sequence on the cathode side of the electrolytic cell bipolar plate, and an anode electrode, a diaphragm, a cathode electrode, a front end current collector plate, a front end insulating plate and a front end plate installed in sequence on the anode side of the electrolytic cell bipolar plate.

[0026] Preferably, further comprising:

[0027] Cathode sealing and anode sealing, the cathode sealing is installed between the cathode face sealing water line of the cathode side of the bipolar plate and the diaphragm, and between the diaphragm and the front end current collector plate on the anode side of the bipolar plate, respectively, and the anode sealing is installed between the diaphragm and the rear end current collector plate on the cathode side of the bipolar plate, and between the anode face sealing water line of the anode side of the bipolar plate and the diaphragm.

[0028] In the technical scheme of the utility model, in the cathode flow field area and the anode flow field area of the bipolar plate body, the cathode water drop type flow field and the anode water drop type flow field are used respectively, the fluid distribution is more uniform than the traditional papillary structure flow field, in addition, the contact area of the top of the cathode water drop type flow field with the cathode electrode in the electrolytic cell and the contact area of the top of the anode water drop type flow field with the anode electrode in the electrolytic cell are larger than the papillary structure, the contact area can be effectively increased, thereby the contact resistance is reduced, the electric energy loss is reduced, the electrolytic cell temperature is more uniform, and the electrolytic cell is more uniform. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical scheme in the embodiments of the utility model or the prior art, the drawings needed to be used in the embodiment or the prior art description will be briefly introduced below, and obviously, the drawings in the following description are only some embodiments of the utility model, and for those skilled in the art, other drawings can be obtained according to these drawings without creating labor.

[0030] Figure 1 It is the cathode side schematic diagram of the bipolar plate body of the utility model;

[0031] Figure 2 It is the anode side schematic diagram of the bipolar plate body of the utility model;

[0032] Figure 3 It is the schematic diagram of the liquid inlet metal sheet and the gas-liquid outlet metal sheet of the bipolar plate of the utility model;

[0033] Figure 4 It is the schematic diagram of the electrolytic cell explosion of the utility model;

[0034] Figure 5 It is the schematic diagram of the cathode water drop type flow field and the anode water drop type flow field of the utility model.

[0035] 1, plate body; 2, cathode flow field area; 3, cathode water drop type flow field; 4, cathode lye inflow flow field channel; 5, cathode lye inflow main flow channel; 6, anode lye inflow flow field channel; 7, anode lye inflow main flow channel; 8, cathode face sealing water line; 9, cathode lye hydrogen gas outflow flow field channel; 10, cathode lye hydrogen gas outflow main channel; 11, anode lye hydrogen gas outflow main channel; 12, anode lye hydrogen gas outflow flow field channel; 13, anode water drop type flow field; 14, anode flow field area; 15, anode face sealing water line; 16, electrolytic cell stack mounting positioning hole; 17, rear end plate; 18, rear end insulating plate; 19, rear end current collecting plate; 20, electrolytic cell bipolar plate; 21, anode electrode; 22, anode seal; 23, diaphragm; 24, cathode seal; 25, cathode electrode; 26, front end current collecting plate; 27, front end current collecting plate seal; 28, front end insulating plate; 29, front end plate seal; 30, front end plate; 31, plate liquid inlet metal sheet; 33, gas-liquid outlet metal sheet. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical scheme and advantages of the utility model more clear, the technical scheme of the utility model will be described in detail below. Obviously, the described embodiment is only a part of the embodiment of the utility model, not all the embodiment. Based on the embodiment in the utility model, all other embodiments obtained by the ordinary skill in the art without making the creative labor belong to the scope of the utility model.

[0037] Reference Figures 1-5 The embodiment of the utility model provides a kind of electrolytic cell bipolar plate, comprising:

[0038] Plate body 1;

[0039] Cathode flow field area 2 and anode flow field area 14, cathode flow field area 2 is set in the cathode side of plate body 1, and anode flow field area 14 is set in the anode side of plate body 1;

[0040] Cathode water drop type flow field 3 and anode water drop type flow field 13, several cathode water drop type flow fields 3 are equidistantly set in cathode flow field area 2, and contact setting with cathode electrode 25 in electrolytic cell, and several anode water drop type flow fields 13 are equidistantly set in anode water drop type flow field 13, and contact setting with anode electrode 21 in electrolytic cell.

[0041] Generally, nickel mesh is placed as an electrode on both sides of the diaphragm, placed between two plates, sealed by a sealing ring between the two plates; the surface area of the nickel mesh electrode is limited, it is difficult to increase the reaction area, and the contact area between the nickel mesh and the diaphragm plate is small, the current density is small, which causes large contact resistance, and large ohmic loss is easily generated. In the cathode flow field area 2 and the anode flow field area 14 of the plate body 1, the cathode water drop type flow field 3 and the anode water drop type flow field 13 are respectively used, and the fluid distribution is more uniform than the traditional papillary structure flow field; in addition, the contact area of the top of the cathode water drop type flow field 3 with the cathode electrode 25 in the electrolytic cell and the contact area of the top of the anode water drop type flow field 13 with the anode electrode 21 in the electrolytic cell are larger than the papillary structure, which can effectively increase the contact area, thereby reducing the contact resistance and reducing the power loss, and is beneficial to make the temperature of the electrolytic cell more uniform.

[0042] Further optimization scheme, further comprising:

[0043] Liquid inlet channels, a plurality of liquid inlet channels are arranged at the first end of the plate body 1 and are respectively communicated with the cathode flow field area 2 and the anode flow field area 14;

[0044] Gas-liquid channels, a plurality of gas-liquid channels are arranged at the second end of the plate body 1 and are respectively communicated with the cathode flow field area 2 and the anode flow field area 14.

[0045] The main function of the liquid inlet channel is to respectively transport the lye into the cathode flow field area 2 and the anode flow field area 14, under the action of the cathode water drop type flow field 3 and the anode water drop type flow field 13, the lye, hydrogen and oxygen generated by electrolysis can be discharged from the electrolytic chamber through the gas-liquid channel in time, which is beneficial to the progress of the reaction.

[0046] Further optimization scheme, the liquid inlet channel comprises:

[0047] The cathode lye flows into the main flow channel 5, a plurality of cathode lye flow-in main flow channels 5 are arranged at the first end of the plate body 1 and are communicated with the cathode flow field area 2;

[0048] The anode lye flows into the main flow channel 7, a plurality of anode lye flow-in main flow channels 7 are arranged at the first end of the plate body 1 and are communicated with the anode flow field area 14;

[0049] The cathode lye flows into the flow field channel 4, the cathode lye flow-in flow field channel 4 is arranged at the first end of the plate body 1 and is communicated between the cathode lye flow-in main flow channel 5 and the cathode flow field area 2, the plate liquid inlet metal sheet 31 is fixed (welded) on the cathode side of the plate body 1 and forms the cathode lye flow-in flow field channel 4 between the plate body 1;

[0050] Anode lye inflow flow field channel 6 is opened in the first end of the polar plate body 1 and is communicated between the anode lye inflow main flow channel 7 and the anode flow field area 14. The polar plate inflow metal sheet 31 is fixed (welded) on the anode side of the polar plate body 1 and forms the anode lye inflow flow field channel 6 with the polar plate body 1.

[0051] The lye flows into the cathode flow field area 2 through the cathode lye inflow main flow channel 5 and the cathode lye inflow flow field channel 4 in sequence and then flows out from the gas-liquid channel. The lye flows into the anode flow field area 14 through the anode lye inflow main flow channel 7 and the anode lye inflow flow field channel 6 in sequence and then flows out from the gas-liquid channel.

[0052] Further optimization scheme, the gas-liquid channel includes:

[0053] Cathode lye hydrogen outflow main channel 10 is opened in the second end of the polar plate body 1 and is communicated with the cathode flow field area 2.

[0054] Anode lye hydrogen outflow main channel 11 is opened in the second end of the polar plate body 1 and is communicated with the anode flow field area 14.

[0055] Cathode lye hydrogen outflow flow field channel 9 is opened in the second end of the polar plate body 1 and is communicated between the cathode lye hydrogen outflow main channel 10 and the cathode flow field area 2. The gas-liquid outlet metal sheet 33 is fixed (welded) on the cathode side of the polar plate body 1 and forms the cathode lye hydrogen outflow flow field channel 9 with the polar plate body 1.

[0056] Anode lye hydrogen outflow flow field channel 12 is opened in the second end of the polar plate body 1 and is communicated between the anode lye hydrogen outflow main channel 11 and the anode flow field area 14. The gas-liquid outlet metal sheet 33 is fixed (welded) on the anode side of the polar plate body 1 and forms the anode lye hydrogen outflow flow field channel 12 with the polar plate body 1.

[0057] The hydrogen and oxygen generated in the cathode flow field area 2 are discharged with the electrolyte through the cathode lye hydrogen outflow flow field channel 9 and the cathode lye hydrogen outflow main channel 10 in sequence. The hydrogen and oxygen generated in the anode flow field area 14 are discharged with the electrolyte through the anode lye hydrogen outflow flow field channel 12 and the anode lye hydrogen outflow main channel 11 in sequence.

[0058] The application provides a zero-spacing non-polar frame alkaline water hydrogen production electrolytic cell, which comprises the electrolytic cell bipolar plate, and further comprises a cathode electrode 25, a diaphragm 23, an anode electrode 21, a rear end current collector plate 19, a rear end insulating plate 18 and a rear end plate 17 which are sequentially installed on the cathode side of the electrolytic cell bipolar plate 20, and an anode electrode 21, a diaphragm 23, a cathode electrode 25, a front end current collector plate 26, a front end current collector plate seal 27, a front end insulating plate 28, a front end plate seal 29 and a front end plate 30 which are sequentially installed on the anode side of the electrolytic cell bipolar plate.

[0059] Further comprising:

[0060] The cathode seal 24 and the anode seal 22 are respectively installed between the cathode surface sealing water line 8 and the diaphragm 23 on the cathode side of the bipolar plate 20, and between the diaphragm 23 and the front end current collector plate 26 on the anode side of the bipolar plate 20.

[0061] The existing alkaline water electrolytic cell mainly comprises an electrolytic cell chamber composed of a polar plate, a nickel mesh, a diaphragm and a sealing ring, and is composed of electrolytic cell chambers in series. A 30% potassium hydroxide solution is used as the electrolyte, and the working temperature is 85-95°C. The polar plate is usually welded by a polar frame and a polar plate, the polar frame is machined, the papillary structure on the polar plate is stamped and formed, and both the front and back surfaces have the papillary structure. The nickel mesh is placed on both sides of the diaphragm as an electrode and is placed between the two polar plates, and the two polar plates are sealed by a sealing ring. The surface area of the nickel mesh electrode is limited, and it is difficult to increase the reaction area. Moreover, the direct contact area between the nickel mesh and the diaphragm polar plate is small, the current density is small, the contact resistance is large, and a large ohmic loss is easily generated. In addition, the metal and carbon steel are processed, the volume and weight are large, the thickness of the polar frame is more than 10 mm, the thickness of the sealing gasket is more than 3-5 mm, the size of a single section is large, and the material utilization rate is not high. In the present application, the thickness of the electrolytic cell chamber is reduced, the thickness of a single section is reduced from 13-15 mm to 5 mm, the volume of the electrolytic cell is reduced, and a water droplet-shaped point flow field is adopted. Compared with the traditional papillary structure flow field, the fluid distribution is more uniform. The contact area between the top plane and the electrode is much larger than that of the papillary structure, which can effectively increase the contact area and reduce the contact resistance, thereby reducing the power loss and making the electrolytic cell temperature more uniform. The polar plate body 1 of the present application can be made of an alkali-resistant material such as nickel, titanium, or can be made of carbon steel or stainless steel with a nickel-plated surface to reduce the cost.

[0062] Before the electrolytic cell is installed, it is necessary to ensure that all components are ready and undamaged.

[0063] Assembling the rear end part: Place the rear end plate 17 at the bottom as the base of the electrolytic cell; place the rear end insulating plate 18 on the rear end plate to isolate the electrical connection; install the rear end current collector plate 19 on the rear end insulating plate 18, ensuring that it is flat and in the correct position.

[0064] Installing the anode electrode: Place the cathode flow field area 2 on one side of the rear end current collector plate 19, ensuring that it is flat and in the correct position; place the anode electrode 21 inside the anode seal 22 and tightly fit it with the rear end current collector plate 19.

[0065] Installing the diaphragm: Place the diaphragm 23 on the anode electrode 21, ensuring that the diaphragm 23 is flat and has no wrinkles, and the diaphragm 23 serves to separate the anode and cathode to prevent direct contact between them.

[0066] Installing the cathode part: Install the cathode seal 24 on the diaphragm 23, and then place the cathode electrode 25.

[0067] Installing the bipolar electrode: Place the electrolytic cell bipolar plate 20 on the cathode electrode 25 and align it to press it flat, ensuring good sealing between the cathode seal 24.

[0068] Repeating the installation: According to the number of electrolytic cell chambers, install the anode electrode 21, anode seal 22, diaphragm 23, cathode seal 24, cathode electrode 25, bipolar plate 20 in sequence, complete the assembly, and the last group does not install the bipolar plate 20.

[0069] Assembling the front end part: Place the front end current collector plate 26 on the cathode electrode 25, ensuring that it is flat and in the correct position. Install the front end current collector plate seal 27 on the front end current collector plate 26 to ensure sealing. Place the front end insulating plate 28 on the front end current collector plate seal 27 to isolate the electrical connection.

[0070] Finally, install the front end plate seal 29 on the front end insulating plate 28, and then place the front end plate 30 on the topmost part, lock the rear end plate 17 and the front end plate 30 with the screw rod, and complete the assembly of the electrolytic cell.

[0071] It should be noted that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise" and the like indicated in this paper indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing this application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting this application. In addition, the terms "first", "second", "third" and the like are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0072] In the description herein, it also needs to be explained that, unless explicitly specified and limited, the terms "mount", "connect", "connection" should be understood broadly, for example, can be fixed connection, can also be detachable connection, or integrally connected; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through intermediate medium. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0073] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An electrolyser bipolar plate characterised in that, Comprise: Polar plate body (1); Cathode flow field area (2) and anode flow field area (14), the cathode flow field area (2) is arranged in the cathode side of the polar plate body (1), the anode flow field area (14) is arranged in the anode side of the polar plate body (1); Cathode water drop type flow field (3) and anode water drop type flow field (13), several cathode water drop type flow field (3) are equidistantly arranged in the cathode flow field area (2), and are in contact with the cathode electrode (25) in electrolytic cell, several anode water drop type flow field (13) are equidistantly arranged in the anode water drop type flow field (13), and are in contact with the anode electrode (21) in electrolytic cell.

2. The electrolyser bipolar plate of claim 1, characterised in that, Further comprise: Liquid inlet channel, several liquid inlet channels are opened in the first end of the polar plate body (1), and are respectively communicated with the cathode flow field area (2), anode flow field area (14); Gas-liquid channel, several gas-liquid channels are opened in the second end of the polar plate body (1), and are respectively communicated with the cathode flow field area (2), anode flow field area (14).

3. The electrolyser bipolar plate of claim 2, characterised in that, The liquid inlet channel comprises: Cathode lye inflow main flow channel (5), several cathode lye inflow main flow channels (5) are opened in the first end of the polar plate body (1), and are communicated with the cathode flow field area (2); Anode lye inflow main flow channel (7), several anode lye inflow main flow channels (7) are opened in the first end of the polar plate body (1), and are communicated with the anode flow field area (14).

4. The electrolyser bipolar plate of claim 3, wherein, Further comprise: Cathode lye inflow flow field channel (4), the cathode lye inflow flow field channel (4) is opened in the first end of the polar plate body (1), and is communicated between the cathode lye inflow main flow channel (5) and the cathode flow field area (2); Anode lye inflow flow field channel (6), the anode lye inflow flow field channel (6) is opened in the first end of the polar plate body (1), and is communicated between the anode lye inflow main flow channel (7) and the anode flow field area (14).

5. The electrolyser bipolar plate of claim 2, wherein The gas-liquid channel comprises: Cathode lye hydrogen gas outflow main channel (10), several cathode lye hydrogen gas outflow main channels (10) are opened in the second end of the polar plate body (1), and are communicated with the cathode flow field area (2); Anode lye hydrogen gas outflow main channel (11), several anode lye hydrogen gas outflow main channels (11) are opened in the second end of the polar plate body (1), and are communicated with the anode flow field area (14).

6. The electrolyser bipolar plate of claim 5, wherein, The gas-liquid channel comprises: Cathode lye hydrogen gas outflow flow field channel (9), the cathode lye hydrogen gas outflow flow field channel (9) is opened in the second end of the polar plate body (1), and is communicated between the cathode lye hydrogen gas outflow main channel (10) and the cathode flow field area (2); Anode lye hydrogen gas outflow flow field channel (12), the anode lye hydrogen gas outflow flow field channel (12) is opened in the second end of the polar plate body (1), and is communicated between the anode lye hydrogen gas outflow main channel (11) and the anode flow field area (14).

7. A zero-gap frameless alkaline water hydrogen production electrolyzer characterized in that, The bipolar plate of the electrolytic cell according to any one of claims 1-6, further comprising a cathode electrode (25), a diaphragm (23), an anode electrode (21), a rear end current collector plate (19), a rear end insulating plate (18) and a rear end plate (17) installed in sequence on the cathode side of the bipolar plate (20), and an anode electrode (21), a diaphragm (23), a cathode electrode (25), a front end current collector plate (26), a front end insulating plate (28) and a front end plate (30) installed in sequence on the anode side of the bipolar plate.

8. The zero-gap non-polar frame alkaline water hydrogen electrolyzer of claim 7, wherein, Further comprising: a cathode seal (24) and an anode seal (22), the cathode seal (24) being installed between the cathode face seal water line (8) on the cathode side of the bipolar plate (20) and the diaphragm (23), and the anode seal (22) being installed between the diaphragm (23) on the anode side of the bipolar plate (20) and the front end current collector plate (26), respectively, and the diaphragm (23) on the cathode side of the bipolar plate (20) and the rear end current collector plate (19), and the diaphragm (23) on the anode side of the bipolar plate (20) and the anode face seal water line (15), respectively.

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