H-tec Education e208 User manual

Operating Instructions

E208 - 1-Cell Rebuildable PEM Electrolyzer Kit

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Table of Contents

Introduction

Intended Use

General Safety Precautions

Contents

Required Additional Components/Equipments

Optional Equipments

Operation of a PEM Electrolyzer

Different Operational Modes for Electrolyzers

Assembly/Disassembly

Operation of the Electrolyzer Cell

Technical Data

Troubleshooting

Disposal

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Introduction

Diminishing resources, more severe environmental impacts originated from the current power

plants, and the ever-increasing demand for energy forces us to re-evaluate the structure of our

energy storage supply systems. Automobile and oil companies increasingly invest in hydrogen

technologies (such as fuel cells, electrolyzers, etc.) because such clean technologies offer

smart and innovative solutions to some of these future energy related concerns. The Proton

Exchange Membrane (PEM) Electrolyzer is one of the most fascinating, clean electrochemical

technologies. It provides a unique and highly efficient energy storage via an electrolysis

reaction, with minimal impact on our natural resources.

It is important to learn about this technology, especially for young people, who will most likely

spend a large part of their lives with it.

The 1-Cell Rebuildable PEM Electrolyzer Kit offers the possibility to become familiar with

hydrogen technologies (particularly generation of hydrogen) in a step-by-step procedure, by

way of simple experiments.

The 1-Cell Rebuildable PEM Electrolyzer Kit represents the state-of-the-art technology for

the components that are used in the hardware. It can be used for practical demonstration

of the operation of electrolyzers (which are also known as hydrogen generators in the

industry) by means of simple experiments. This electrochemical cell can be completely

dismantled (meaning disassembled and reassembled) and can therefore also be used for vivid

demonstration of an electrolyzer design to students or researchers.

The 1-Cell Rebuildable PEM Electrolyzer Kit is consistently environmentally conscious in all

operating modes, requiring only de-ionized or distilled water and a small power supply for the

generation of hydrogen and oxygen gases from the electrolysis reaction of water.

All steps required for setup, operation, and assembly/disassembly of the 1-Cell Rebuildable

PEM Electrolyzer Kit are described in this manual.

Please read through the Operating Instructions carefully before operation.

H-TEC Education wishes you many enjoyable hours learning about this tecH-TEC Education wishes you many enjoyable hours learning about this technology with thehnology with the

1-Cell Rebuildable PEM Electrolyzer Kit.1-Cell Rebuildable PEM Electrolyzer Kit.

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Intended Use

The 1-Cell Rebuildable PEM Electrolyzer Kit allows the measurement and demonstration of the

principles of Proton Exchange Membrane (PEM) Electrolyzers and PEM Fuel Cells. The system has

been developed for teaching and demonstration purposes only.

Any other use is prohibited!

De-ionized or distilled water, a power supply, and a multimeter are required for the operation of

the 1-Cell Rebuildable PEM Electrolyzer Kit.

Should the equipment be used improperly, the generated hydrogen and oxygen gases present

a hazard. Additionally, the externally attached power supply may also become a point of hazard

in the case of incorrect usage of this educational PEM Electrolyzer Kit. To prevent accidents,

observe the General Safety Precautions at all times when working with the 1-Cell Rebuildable

PEM Electrolyzer Kit.

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• The system is intended for teaching

and demonstration purposes in schools,

universities, institutions, and companies

only.

• It may only be set up and operated by a

competent person.

• Read the Operating Instructions before

setting up the 1-Cell Rebuildable PEM

Electrolyzer Kit. Follow them during

use and keep them readily available for

reference.

• Wear protective goggles and other PPEs.

• Remove inflammable gases, vapors, and

fluids from the vicinity of electrolyzers

and fuel cells. The catalysts contained

in the system can trigger spontaneous

combustion.

• Hydrogen and oxygen are

the two main gases that are

generated by the electrolyzer

system. To prevent the

gases collecting and forming

explosive mixtures only use the system

in well-ventilated rooms. Do not obstruct

the inlet and outlet ports of the system

and prevent pressure building up inside

the cell.

• Hoses, plugs, and tanks are used for

pressure compensation. They must

not be fixed or secured with clamps,

adhesive, etc.

General Safety Precautions

• The system is not a toy. Operate the

1-Cell Rebuildable PEM Electrolyzer Kit

according to the instructions provided

in this booklet and keep the cell and the

gases produced by the electrochemical

cell out of the reach of small children.

• Unless specified otherwise, do not

short-circuit or reverse the polarity of the

terminals.

• Do not operate the system dry. Always

ensure that it contains sufficient liquid

de-ionized water or liquid distilled water

at the anode side of the electrolyzer cell.

• The system may only be operated in

a display case, which is sufficiently

ventilated at all times. The operator

is obliged to prove this by means of

appropriate measurements.

• Do not smoke near this device.

• Only use the gas storage tanks belonging

to or supplied with the system to store

the generated gases during the operation

of the electrolysis cell. Never connect

other alternatives.

• Only operate the system at room

temperature and ambient pressure.

• De-ionized water or distilled water needs

to be transferred into the anode side of

the electrolyzer cell in the liquid form or

while its temperature is in the range of

5 deg. Celsius to 60 deg. Celsius. In the

case of using warmed liquid water, the

user needs to use the proper PPE.

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• Do not operate the system dry. Always

ensure that it contains sufficient amount

of liquid de-ionized water or liquid

distilled water at the anode side of the

electrolyzer cell.

• Remove anything in the vicinity

of the electrolyzer cell that may

ignite the generated hydrogen

gas (naked flame, materials

that can become charged with static

electricity, substances with catalytic

properties such as platinum powder,

etc.).

• Remove all the substances from

the vicinity of the system that could

spontaneously ignite with increased

oxygen concentration.

• Tell the students about any potential

dangers and carefully supervise

experimentation.

General Safety Precautions

• Hoses, plugs, and tanks, etc. are used for

pressure compensation. They must not

be fixed or secured or obstructed with

clamps, adhesive, stoppers, etc.

• The power source of this electrolyzer

can be based on solar sources too. Do

not position any solar modules and

lights in use closer than the minimum

permitted distance (50 cm between

H-TEC Education solar modules and the

H-TEC Education Spotlight, or see other

manufacturers’ stipulations).

• The surface of solar modules can get

very hot during extended operation.

H-TEC Education does not accept responsibility for injuries or damage sustained in the event ofH-TEC Education does not accept responsibility for injuries or damage sustained in the event of

these Safety Precautions not being followed.these Safety Precautions not being followed.

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Contents

Housing plates

Recessed hex-head

screws & washer

Fittings

Catalyst

coated

membrane

Nuts

Fittings

Perforated plates

with electrodes

This PEM electrolyzer cell can be fully disassembled and re-assembled in order to see the design

aspect and the internal components for educational purposes.

Required Additional

Components/Equipments:

•• Commercial distilled waterCommercial distilled water (or(or

deionized water)deionized water) with a conduc-

tivity of < 2 µS/cm

• Connecting hoses

• Power supply (0 to 2.5 V and 0 to

5 Amps)

• Multimeter

Optional Equipments:

• Fuel Cell H2/O2/Air

Item No: F103

• Storage 80

Item No: A153

This PEM electrolyzer cell can also be used in conjunction with other educational fuel cell kits in

order to consume the generated hydrogen and oxygen gases to produce electrical energy.

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Operation of a PEM Electrolyzer Cell

In an electrolyzer cell, the electrical energy that is being provided from an external source is used

to split the de-ionized water (or distilled water) in order to generate hydrogen and oxygen gases.

In other words, electrical energy is being converted into chemical energy with the aid of the

electrolyzer cell. This electrochemical reaction is also known as electrolysis.

In the electrolyzer cell, the electrochemical reactions are carried out on the catalyst located

at the anode and cathode. In PEM electrolyzers, anode and cathode catalysts are usually

applied directly to the surface of the membrane. Sometimes, only the anode electrode catalyst

is applied to the membrane surface and cathode catalyst is applied to the surface of the gas

diffusion layer. An example for anode catalyst is iridium ruthenium oxide or iridium black. An

example of cathode catalyst is platinum black or platinum on carbon. As the name suggest, PEM

electrolyzers utilize a proton (H+) exchange membrane (such as Nafion). In addition to these

components, a metallic diffusion medium is used at the anode side to evenly disperse the liquid

water, vent out the generated gases, and provide electrical contact. At the cathode, on the other

hand, a carbon based gas diffusion layer is used to vent out the hydrogen gas and also provide

electrical contact.

The combination membrane-catalysts-diffusion media forms the heart of the PEM electrolyzer

cell. The following reactions take place within the PEM electrolyzer system:

Cathode:

4e-+ 4H+2H2

Anode:

2H2O O2 + 4H++ 4e-

Complete reaction:

2H2O 2H2+ O2

In this 1-Cell Rebuildable PEM Electrolyzer Kit, de-ionized water (in the liquid phase) is supplied

to the anode chamber. Under the catalytic action of the anode electrode, water molecules get

oxidized to oxygen gas, protons (H+), and electrons (e-) on the surface of the catalyst particles.

The H+ions migrate through the proton-conductive membrane to the cathode side due to the

existing cell voltage gradient. The electrons, on the other hand, travel to the cathode through

the external electrical circuit and recombine with protons in order to generate the hydrogen gas.

At the anode, an oxidation reaction would occur. At the cathode, on the other hand, a reduction

reaction would occur. In any electrochemical cell (whether using an electrolyzer or fuel cell),

an oxidation reaction has to accompany a reduction reaction in order to maintain the ion and

electron neutrality.

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Diﬀerent Operational Modes for Electrolyzers

“Anode-fed” versus “Cathode-fed” electrolysis modes“Anode-fed” versus “Cathode-fed” electrolysis modes

PEM electrolyzer hardware are usually configured to work in one of the following mode: anode-

fed or cathode-fed. The mode of operation is usually dictated by the application itself. For

example, if the application requires pure hydrogen with minimal moisture content, the anode-

fed design is more efficient. If the application requires pure oxygen with minimal moisture, the

cathode-feed design is more applicable.

In the anode-fed configuration, the liquid de-ionized water is transferred to the anode chamber.

On the other hand, the cathode-fed mode requires the liquid de-ionized water to be transferred to

the cathode chamber.

Anode-fed configuration would usually have the following sub-components in the electrolyzer

cell as its diffusion media: carbon-based gas diffusion layer for the cathode and metallic mesh

or metallic screen for the anode. Cathode-fed electrolyzers, on the other hand, would have the

following as its diffusion media: metallic mesh or metallic screen for anode and metallic mesh or

metallic screen for the cathode.

Since electrolysis reaction requires the water to be present on the anode electrode catalyst layer,

anode-fed designs are more efficient compared to cathode-fed designs. While anode-fed design

allows the water to be transferred directly to the anode catalysts, the cathode-fed design would

have to wait for water molecules to be transferred from cathode side to the anode through the

membrane (natural diffusion, which is a slow process) before the electrolysis reaction can start.

1-Cell Rebuildable PEM Electrolyzer Kit is based on anode-fed electrolysis mode and hence, it

requires the de-ionized water to be transferred to the anode chamber. De-ionized water can

be transferred to the anode inlet port via two simple mechanisms: gravity-fed by using another

H-TEC Education product such as Storage 80 (Item No: A153) or forcefully-fed (also known as

active-fed approach) with the help of a small liquid pump. If the gravity-fed approach is being

used, the user should store the water in a manner such that the water level is higher than the top

port on the electrolyzer. If the user is intending to use a small liquid pump, there is no need to

place the storage tank at a higher level because mechanical movement of the pump will actively

push the water. The maximum amount of water to be pumped is not to exceed 70-80 milliliters

per minute. Too much water flow can create leaks around the seals.

In order to prevent damage to the cell, the anode should remain full of water at all times.

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Diﬀerent Operational Modes for Electrolyzers

“Anode-fed” electrolysis mode“Anode-fed” electrolysis mode

Before attaching the power supply to the electrolysis cell, it is advised to follow the following

steps:

1. Obtain a pure de-ionized water (or distilled water) in sufficient quantities. 500 mL to 1000 mL

of volume of water can be used for multiple hours.

2. Transfer a sufficient amount of water in to the water storage tank that you will be using for the

electrolysis experiment.

3. Use a soft tubing (such as silicone tubing) of the appropriate diameter to make a connection

between the water storage tank and the inlet of the anode side of the electrolyzer cell.

4. Attach another piece of soft tubing to the outlet of the anode side of the electrolyzer and place

the end of this tube into the water storage tank. (During the electrolysis reaction, only a small

quantity of liquid water is used and unconsumed water should be recycled back into the storage

tank for further use and reduce waste).

5. Attach soft tubing to inlet and outlet ports of the cathode side (one piece of tubing for each

port) where hydrogen generation will occur and place the ends of these tubes into another empty

storage vessel. During the electrolysis reaction, some of the water will be carried over to the

cathode side and if desired, this water can also be recycled. CAUTION: Do not place the cathodeCAUTION: Do not place the cathode

side tubings’ end to the storage that has anode side tubings. Hydrogen and oxygen mixtures canside tubings’ end to the storage that has anode side tubings. Hydrogen and oxygen mixtures can

easily create a gas mixture with explosive nature and cause serious injuries.easily create a gas mixture with explosive nature and cause serious injuries.

6. Place the anode side and cathode side storages away from each other in order to prevent

formation of explosive gas mixtures. Ensure the area is well ventilated.

7. Do not restrict the liquid or gas flows through the tubings. Do not restrict the inlet and outlet

ports located at the anode and cathode sides. Pressurization inside the electrolysis cell can

cause leakages and possibly damaging the membrane and hence, the hardware.

8. Temperature of the de-ionized water can be in the range of 5° to 60° Celsius. Use caution

with warmed or hot water and use proper personal protective equipments (PPEs, safety glasses

or safety googles, gloves, heat resistant gloves, lab coat, etc.) for the safe operation of the

hardware and safety of the user.

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1. Remove the black hose fittings from the acrylic plates. Loosen the four nuts and remove the

four recessed hex-head screws holding the cell together.

2. Remove the acrylic endplate.

3. Carefully remove the perforated plates from the housing plates while the membrane, cathode

electrode, and anode diffusion medium are still sandwiched between the two perforated plates.

4. Then, carefully remove the top perforated plate from the rest of the components. It is possible

that either the cathode electrode or anode diffusion medium may still be adhered to it (depending

on which side you have started to disassemble). Then remove the membrane and the other

perforated plate.

Assembly

Disassembly

The 1-Cell Rebuildable PEM Electrolyzer Kit can be completely dismantled. This hardware can be

fully disassembled and then reassembled for educational reasons. Note that the catalyst coated

membrane (also called CCM) and the electrodes are extremely sensitive components. They can

be removed from the cell and shown to students. However, we strongly advise against passing

these components around the class.

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1. Place a washer over each of the four bolts.

Insert the bolts into one of the housing plates

and turn them so the housing plate rests upon

the bolt heads (If the black fittings are removed

from the housing plate, this operation can be

performed on a flat bench top).

2. Place one of the perforated plates on the

acrylic housing. The thicker side of the seal

should face the acrylic housing plate.

3. If you have started to assemble from the

anode side first, then place the anode metallic

diffusion medium onto perforated plate, proceed

as follows:

• Place the metallic diffusion medium on the

perforated plate.

• Ensure the orientation of the metallic

diffusion medium is correct. The perforated

plates would have black colored overmold

and the metallic diffusion medium needs to

stay within that area that looks like a frame.

• Ensure the electrode is centered and not

overlapping on the overmold area.

4. Remove the membrane from the deionized

water, holding it at two opposite corners.

Place it, while still wet, upon the metallic

diffusion media. The anode catalyst side

(matte finish) has to face towards the metallic

diffusion medium and physically contact it. The

membrane and metallic diffusion medium are

held in position by the moisture.

Assembly

Before refitting the membrane, allow it to soak for at least 5 minutes in deionized water.

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5. Place the cathode electrode (catalyzed

carbon-based gas diffusion layer) onto the

membrane surface. (The catalyzed side of the

cathode electrode would be dark black color

and the back side of the electrode would have a

lighter gray color. The catalyzed side needs to

face towards the membrane). The orientation

of the cathode electrode should mirror the

black pattern existing on the membrane.

The orientation of the two electrodes must

correspond. The second electrode must fit within

the frame when the second perforated plate is

placed in position.

6. Place the second perforated plate in position.

The thicker side of the seal must face towards

the acrylic housing plate which is not yet in

place. The two banana jacks should be facing

the same direction.

7. Place the second acrylic housing on the bolts.

8. Place the remaining washers and nuts on the

bolts, and screw the nuts finger-tight at first.

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9. Tighten the nuts alternately a little at a time

(max. 2.5 turns) until a gap of 4mm is left

between the acrylic plates.

Caution!Caution!

Overtightening may damage the electrodes. We

recommend that the distance be checked by a

caliper. Should a caliper or similar instrument

not be available, tighten the nuts twice,

approximately half a turn each time.

10. Screw the fittings into the four holes in the

housing plates.

Operation of the Electrolyzer Cell

1. Obtain a small variable/adjustable DC power supply that can provide 0-5 V and 0-10 A.

2. Before connecting the power supply to the electrolyzer, set the max. voltage of the power

supply to 2.1 - 2.2 Volts (voltage limited mode). Ensure that the knob for electrical current is set

to 0 A before the electrolysis test. During the testing of the electrolyzer cell, it is suggested that

the user vary the current while limiting the voltage.

3. Ensure that the polarity of the connections from the power supply to the electrolyzer electrodes

is done correctly. The positive lead of the power supply needs to be connected to the anode side

electrode which has a red colored 2mm banana plug. The negative lead of the power supply

needs to be connected to the cathode side electrode which has a black colored 2 mm banana

plug.

4. After making the electrical connections, turn on the DC power supply. Slowly adjust the

electrical current value by turning the current knob of the power supply. Most power supplies

will provide readout values both for the voltage and current parameters. A multimeter can be

used to verify the voltage value at the terminals of the electrolyzer cell.

5. The maximum electrical current input value for the 1-Cell Rebuildable PEM Electrolyzer Kit is

approximately 5 Amps (if warmed water at a temperature of 36-39°C is used) and the user can

adjust the knob for the electrical current until 5 A is reached. If the cell voltage reaches to 2 V

before 5 A is achieved, stop and do not increase the current anymore.

6. With the use of room temperature de-ionized water or distilled water, 0-4 A can be achieved

before the cell voltage reaches 2 V. With warmed water that has a temperature range of 36-39°

C, 0-5 A can be achieved before the cell voltage reaches to 2 V.

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Technical Data

H x W x D:

Weight:

H2Output:

O2Output:

Input Voltage Range:

Input Current Range:

Electrode Area:

Guide value for Distilled Water:

Permitted operating pressure:

100 x 80 x 90 mm

0.2 kg

35 mL/min

17.5 mL/min

0 - 2 V

0 - 5 A*

16 cm2

<2 µS/cm

0 - 20 mbar

Troubleshooting

The most frequent causes of faults during operation of electrolyzer are:

Use of contaminated waterUse of contaminated water

This electrolyzer cell has a special membrane and it requires pure de-ionized water or distilled

water for its operation. Use of any other water sources (tap water, lake water, sea water,

etc.) will compromise the functionality of the membrane and lower its ionic conductivity. A

contaminated membrane will have significantly lower performance compared to a non-

contaminated membrane.

Reversed polarity connectionReversed polarity connection

If the power supply connection to the electrolyzer is done wrongly and operated, the cathode

catalyst and cathode gas diffusion layer will be permanently damaged.

ReversedReversed membrane after disassemblymembrane after disassembly

If the catalyzed membrane is not placed correctly after the disassembly of the hardware (such as

anode catalyst side placed toward the cathode’s perforated electrode), the cell will not operate or

internal components may get damaged.

InsufficientInsufficient liquid de-ionized water or running the cell dryliquid de-ionized water or running the cell dry

If the anode chamber does not get sufficient liquid de-ionized water or distilled water or if it

operates in dry mode, components of the cell will get damaged.

*: The amount of electrical current that can be applied to the electrolyzer cell will depend on the temperature of the*: The amount of electrical current that can be applied to the electrolyzer cell will depend on the temperature of the

pure water. With room temperature, it is possible to achieve 0 A to 4 A. With slightly warmed water (about 40pure water. With room temperature, it is possible to achieve 0 A to 4 A. With slightly warmed water (about 40°°C), it isC), it is

possible to achieve 0-5 Amps.possible to achieve 0-5 Amps. CAUTION: The maximum voltage that can be applied to this cell is 2.1 V.CAUTION: The maximum voltage that can be applied to this cell is 2.1 V.

Disposal

Do not dispose of electrolyzer cells or components as general household waste.