Polymer electrolyte membrane

Abstract- In the first portion of the research work, an electrolyzer ( 10.16 centimeter Defense Intelligence Agency and 24.13 centimeters height ) to bring forth H and O was constructed for individual piece O2/H2 fuel cell utilizing cation exchange membrane. The electrolyzer public presentation was tested with 23 % NaOH, 30 % NaOH, 30 % KOH and 35 % KOH electrolyte solution with current input 4 A and 2.84 V from the rectifier. Ratess of volume of H produced were 0.159 cm3/sec, 0.155 cm3/sec, 0.169 cm3/sec and 0.163 cm3/sec severally from 23 % NaOH, 30 % NaOH, 30 % KOH and 35 % KOH solution. Ratess of volume of O produced were 0.212 cm3/sec, 0.201 cm3/sec, 0.227 cm3/sec and 0.219 cm3/sec severally from 23 % NaOH, 30 % NaOH, 30 % KOH and 35 % KOH solution ( 1.5 L ) . In malice of being tested the increased concentration of electrolyte solution, the gas rate does non alter significantly. Therefore, cheap 23 % NaOH electrolyte solution was chosen to utilize as the electrolyte in the electrolyzer. In the 2nd portion of the research work, graphite serpentine flow home bases, fiberglass terminal home bases, chromium steel steel screen electrodes, silicone gum elastics were made to piece the individual piece O2/H2 polymer electrolyte membrane fuel cell ( PEMFC ) .

Keywords- electrolyzer, electrolyte solution, fuel cell, rectifier

Introduction

A fuel cell is an electrochemical device that continuously converts the chemical energy into electric energy ( and some heat ) for every bit long as fuel and oxidizer are supplied. In rule, a fuel cell operates like a battery. Unlike a battery, nevertheless, a fuel cell does non run down or necessitate recharging, it operates softly and expeditiously, and when H is used as fuel, it generates merely power and imbibing H2O. Thus it is a so called zero emanation engine.

The six basic types of fuel cell are classified by the electrolyte that they employ. Low temperature types include the alkalic fuel cell ( AFC ) , direct methyl alcohol fuel cell ( DMFC ) and proton exchange membrane fuel cell ( PEMFC ) . The three high temperature types are phosphorous acerb fuel cell ( PAFC ) , liquefied carbonate fuel cell ( MCFC ) and solid oxide fuel cell ( SOFC ) .

The most representative sorts of fuel cells are the proton exchange membrane fuel cell ( PEMFC ) and the direct methyl alcohol fuel cell ( DMFC ) , which use proton carry oning membranes [ 2 ] . A fuel cell consists of a cardinal electromotive force bed, sandwich between two accelerator beds. Assorted stuffs for these beds are used, but the basic procedure is the same. When a H atom contacts the negative anode accelerator bed, it splits into a proton and an negatron. The proton passes directly through the cardinal electrolyte bed, while the negatron produces electricity as it passes through an external circuit. The circuit returns the negatrons to the positive side of the electrolyte bed, where they bond once more with the protons and articulation with an O molecule, making H2O in the positive cathode bed.

PEMFCs are besides being developed for stationary applications. In the 250-kW scope, Ballard Generation System is presently the lone PEMFC-based developer. Most late, the micro-CHP scope has been claimed by a broad scope of developers. Here, high power denseness non the most important issue. The overall end is the most economic usage of the fuel employed, normally natural gas, in order to bring forth electric power and heat.

MATERIALS AND METHODS

The electrolyzer was constructed with polyvinyl chloride ( PVC ) and the two electrodes were made up of chromium steel steel screen strips.

Design Consideration of Water Electrolyzer

First, the volume of electrolyzer was calculated based on 10.16 cm Defense Intelligence Agency and 24.13 centimeter tallness of electrolyzer. So, the deliberate volume of electrolyzer is 1.96L. Then the lower limit needed volume of electrolyte solution in the electrolyzer was considered. The degree of electrolyte solution in the electrolyzer should be put between the scope of 1.24L and 1.96L.

The volumetric flow rate of H produced from the electrolyzer was considered based on 150 mA/cm2 of current denseness required for 27.82 cm2 surface country of electrode. Harmonizing to the computation, the volumetric flow rate of H produced from the electrolyzer is 1.74 L/hr.

Performance Test of the Electrolyzer

Each of two 100 mesh chromium steel steel strips ( 14.605 centimeter – 1.905 centimeter ) was used as electrodes and tantrum in the electrolyzer. Battery centrifuge sheet was inserted between the two electrodes to insulate one electrode from the other. The electrolyzer was filled with 1.5 L of 23 % NaOH solution. It is of import that the water-electrolyte degree was non to be fallen below the length of interior gas aggregation tubing. Then the top cap with two gas aggregation tubing ( dia = 3.81 centimeter and length = 8.89 centimeter ) was used to lid the electrolyzer filled with electrolyte solution. The volume of H and O gas evolved from the electrolyzer was measured with clip by utilizing rectifier ( 4 A and 2.84 V ) . Experiments were besides conducted with 30 % NaOH, 30 % KOH, 35 % KOH solution.

Required Membrane for Fuel Cell Applications

The proton carry oning polymeric membrane ( the ionomeric membrane ) is the most typical component of the polymer electrolyte membrane fuel cell. In an ion exchange fuel cell, the membrane acts non merely as an electrolyte but besides as a physical barrier between the fuel and oxidizer.

In this survey, the needed membrane was obtained from Nilar Win,2006 [ 4 ] in which the membranes were made from commercial polystyrene. In the first method, the natural polystyrene beads were soaked in propanone and so sulfonated at 105±5 & A ; deg ; C with different clip. In the 2nd method, the natural polystyrene beads were soaked in methyl ethyl ketone and so sulfonated at 90±2 & A ; deg ; C with different clip.

Preparation of Required Parts to Assemble Single Slice O2/H2 PEMFC

PEMFC consists of the MEA ( membrane electrode assembly ) , graphite home bases that serve as both electrodes flow field home bases, electrode music directors, gum elastic gaskets, terminal home bases and barbed hose connections to accept tubing for gas flow, a few prison guards to keep it together and adhering stations for electrical connexions.

The chief constituent of the fuel cell is the MEA which is sandwiched between the two black lead home bases that act as electrodes and gas flow Fieldss. The MEA is composed of a proton exchange membrane with a C paper diffusor loaded with Pt accelerator on either side.

Design Consideration of Single Slice O2/H2 PEMFC

All fuel cells use H as a fuel and O as an oxidizer. The electrolyzer has been constructed to obtain H and O gas required for individual piece O2/H2 PEMFC. Volumetric flow rate of H and O gas evolved from this electrolyzer utilizing 23 % NaOH electrolyte solution were 0.159 cm3/sec and 0.212 cm3/sec severally.

Harmonizing to continuity equation, the cross sectional country of gas flow line for H side is 0.136 cm2. The cross sectional country of gas flow line for O side is the same as that of hydrogen side. Therefore, inside diameter of gas port is 0.366 centimeter and deepness is 0.24 centimeter.

Preparation of Graphite Home plates

Two graphite home bases were prepared to flux O gas and H gas. Each graphite flow field-conductor home base was slabbed into 0.476 centimeter midst. The slabbed home bases were cut to the size of 8.57 cm-6.03 centimeter. Both sides of the home base surfaces were made to be smoothened with emery paper.

It is now ready to bore the holes and to expel the flow Fieldss into the graphite home bases. To bore the four fastener holes at the corner of the black lead home bases, the 0.55 centimeter drill spot was used. The channels were cut onto the graphite home bases with the aid of CNC machine as shown in Fig. 2 ( a ) . Each graphite home base consists of six horizontal channels that are 0.32 cm broad, 0.24 centimeter deepness and spaced about 0.32 centimeters from each other. The six parallel horizontal channels were connected with the curves to finish the serpentine flow Fieldss.

Preparation of Fiberglass End Plates, Silicone Rubbers and Electrodes

The two terminal home bases were cut from a piece of 0.95 centimeters thick fibreglass sheet by agencies of CNC machine. Each fiberglass terminal home base was cut into 8.57 centimeter in length and 6.03 centimeter in breadth. At the corner of each fibreglass terminal plate the four holes ( 0.55 centimeter diameter ) were drilled. The 0.28 centimeter holes for the binding station screw into the top sides of the each terminal home base were drilled. Then the 0.36 centimeter gas port holes were drilled on the border of each terminal home base. The fiberglass terminal home base for hydrogen side and oxygen side.

The 0.05 centimeter midst silicone gum elastic was used for gasket and spacer stuff. The silicone gum elastic sheet was cut by utilizing a knife and scissors. It was usage to do holes for the appropriate fastener holes and gas hole with a 0.55 centimeter clout. The silicone gum elastic for gasket is shown in Fig. 2 ( degree Celsius ) and the silicone gum elastic for spacer stuff.

Decision

To build the H2O electrolyzer the volume of electrolyzer, the sum of electrolyte solution required to utilize in electrolyzer and production rate of H were calculated. The volume of electrolyzer was 1.96 L. The degree of electrolyte solution in the electrolyzer must be put between the scope of 1.24 L and 1.96 L. The public presentation of constructed electrolyzer was tested by changing the concentration of NaOH and KOH solution. Although 30 % KOH electrolyte solution gives the best consequence to obtain higher gas production rate among 23 % NaOH, 30 % NaOH and 35 % KOH, the cheap 23 % NaOH electrolyte solution was chosen to utilize as the electrolyte in the electrolyzer. The constructed H2O electrolyzer was capable of bring forthing H and O to use in the individual piece O2/H2 polymer electrolyte membrane fuel cell. To construct a individual piece O2/H2 polymer electrolyte membrane fuel cell, graphite home bases, fiberglass terminal home bases, electrodes and membranes were made. The ion exchange membrane required to do an MEA ( membrane electrode assembly ) was prepared harmonizing to Nilar Win 2006 [ 4 ] .

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