senior project report

Senior Project Final Project Report

Design, Development and Testing of Hydrogen Purifier System

through the technique of Electrochemical Separation and

optimize the setup based on the plate design

Senior Project - MET 406

Spring Semester 2015

Submitted in Fulfillment of the Requirements for the

Degree of Bachelor of Science in MET

Course Instructor: Dr. Hazem Tawfik

Project work done by,

Pragadeesh Ravichandran

Department of Mechanical Engineering and Technology

Farmingdale State College

Page | 1 Pragadeesh Ravichandran


Note: This paper represents my own work in accordance with University regulations.

I authorize Farmingdale State College, SUNY to lend this project work to other

institutions or individuals for the purpose of scholarly research.


I further authorize Farmingdale State College, SUNY to reproduce this project

work by photocopying or by other means, in total or in part, at the request of other

institutions or individuals for the purpose of scholarly research.




Table of Contents

1. Acknowledgements…………………………………………………………………………………

2. Abstract………………………………………………………………………………………………….

3. Introduction……………………………………………………………………………………………

4. Plate Setup……………………………………………………………………………………………..

5. Plate Design…………………………………………………………………………………………….

6. Design of flow alterations……………………………………………………………………….

7. GC setup for sample analysis…………………………………………………………………..

8. Multimeter Readings………………………………………………………………………………

9. Difficulties encountered…………………………………………………………………….......

10. Tools used………………………………………………………………………………………………

11. Gauges Used………………………………………………………………………………………….

12. Need for the project……………………………………………………………………………….

13. Working of Hydrogen Pump……………………………………………………………………

14. Hydrogen Pump……………………………………………………………………………………..

15. Channel design………………………………………………………………………………………..

16. Thermal Spraying of the plates after creating channels………………………….

17. Assembly of the hydrogen purifier………………………………………………………….

18. Specifications of the product used…………………………………………………………..

19. Setup requirements………………………………………………………………………………..

20. Criteria of judgment………………………………………………………………………………

21. Plots and figures……………………………………………………………………………………

22. Conclusion……………………………………………………………………………………………..



Acknowledgments

I immensely appreciate the guidance and support I have received from

Prof. Dr. Hazem Tawfik (Course instructor) not only during the brief spell I spent in his

lab, but also throughout my part time job experience at Farmingdale State College. He

has offered invaluable advice in his capacities as mechanical department chair and a

subject professor and for that I am grateful.

I like to thank Dan Weinman (Technical Specialist at IRTT) who gave many

technical solutions to this project as a form of sound advice and continuous support.

I extend my gratitude to thank Daniel Boss (Junior in MET) for his extended

support, even over time, in getting the apparatus ready and functioning for his repeated

contributions in that field.

I would especially like to thank Robert Adolfson (Junior in MET) without whose

daily support, perseverance, teachings and patience this project would have floundered.

My special thanks note to Alex Pereira (Graduate Student) for all the clarifications

that was discussed over phone as a telephonic conversation and Tom (Junior in MET) for

his initial guidance in the field relating to this project.

Most importantly, I shall remain forever grateful to my family. Despite being over

10,000 miles away, they have provided nothing but unconditional support throughout



these months. It is them who stood firmly beside me through thick and thin, and got me

to where I am today. I thank them from the bottom of my heart.

Without all of their contributions, this project would have been a real nightmare

and couldn’t have reached this far and completed on time. Their active participation,

involvement and contributions to this project at every stage have really changed the

way this project would have actually progressed.



Abstract

This experimental setup is to propose that Polymer Electrolyte Membrane (PEM)

fuel cells can be used as electrochemical (or hydrogen) pumps. Unlike standard fuel

cells, which generate electricity from the chemical energy released when H2 and O2

combine to form water, electrochemical pumps require power – in the form of

electricity – to pump hydrogen molecules from the anodic to the cathodic

compartments of a cell by transporting them across the PEM. Since the PEM only allows

for the transport of H2 molecules, electrochemical pumps can theoretically be used to

separate hydrogen from streams containing impurities along with the valuable hydrogen

gas. PEM cells as hydrogen pumps is a viable alternative to the high-cost, high-power

separation techniques employed today such as pressure swing adsorption and cryogenic

distillation, especially when it comes to localized settings or to remote applications.

In this investigation, the performance of an electrochemical cell is analyzed with

a current of 1 A applied to the cell. Dirty Gas is fed into the cell at the anode, and pure

hydrogen is received at the cathode. Simulation of 1 cell electrochemical pump is

performed for 4 different plate designs. It is firstly done for 1 pattern flow field to check

if the purifier actually works. Then the same setup is carried out to find out which

pattern when employed would yield better results.



Design, Development and Testing of Hydrogen Purifier System through

the technique of Electrochemical Separation and

optimize the setup based on the plate design

Objective:

To create a system through electrochemical separation that filters pure hydrogen from the dirty gas inlet and optimize the assembly adapting the best plate design.

Introduction:

This process aims to purify hydrogen by filtering it out from the mixture of other gases passed through the system. The system is designed in such a way that it has an ability to selectively separate and extract hydrogen gas from its inlet. Regarding the design aspects of hydrogen purifier separator plates, they have 3 ports,

i) the first functions as an inlet to the dirty gas mixture which consists of all gases (unwanted plus hydrogen),

ii) the second functions as an outlet port as an exit to unwanted gases separated from hydrogen and

iii) the third serves as an exit to the pure hydrogen.

Inlet: Dirty gas with hydrogen

Outlet 1: Dirty gas without hydrogen; Outlet 2: Pure hydrogen

[Undesired gas + Desired gas (Hydrogen)] Undesired gas + Desired gas (Hydrogen)

Comes together as one gas stream and leaves separately as two gas streams.

There is a minimal difference between a hydrogen purifier and a hydrogen fuel cell. A hydrogen fuel cell could function as a hydrogen purifier as well, except the fact that current is passed onto the purifier whereas, the current is derived from hydrogen fuel cell. Although because of the losses, the current produced by the fuel cell stack wouldn’t be enough to power up the same setup when run as a hydrogen purifier, it is still



employed as the sole purpose is to purify the hydrogen. It is also called a hydrogen pump as the flow is accelerated by an external power supply or source.

Plate Setup:



Plate Design:

Design of Flow alterations:

GC Setup for sample analysis:



The gas that is to be detected and analyzed in the GC is hydrogen. As the principle of GC works on the basis of thermal conductivity of the sample gas, the usage of carrier gas should have distinct properties from that of the sample being analyzed. Hence, helium can’t be used as an inert gas to this analysis. Nitrogen is employed in place of helium as it is little apart from hydrogen in the periodic table.

Multi meter Readings:

Resistance in Ω (Ohms)

Collector – Plate 1 Plate 1 – Plate 2 Plate 2 - Collector Collector - Collector

1 pattern 0.4 35.56 0.3 37.4

3 pattern 0.6 74.2 0.5 85.7

5 pattern 1.2 221.5 0.9 230.4

7 pattern 1.5 174.4 0.2 190.8

Difficulties encountered:



The use of stainless steel material to this application was a major challenge that was

faced. As the material is hard and very tough to machine, it resulted into various other

challenges like,

a. Breakage of tools in the CNC machine while in operation

b. Insufficient tool length available to drill the plates for the entry and exit.

c. Unavailability of harder drill bit.

Other challenges were namely,

a. Collision of the collet with the plate because of the narrow drilling angle.

b. Milling the end plates with proper alignment of the guide pins and clamp pins.

c. Bridging the channels using JB weld and thermal spraying the plates before.

d. Altering to different designs

e. Machine Capability

f. Easy to sample through septum ports.

g. Connections that fit both the requirements (High scale and the low scale).

h. Ensuring the right proportions in GC quantitatively.

i. Time constraint was really a big challenge.

Tools used:



Gauges Used:

Need for the project:



One of the pressing issues facing the world today is the expected depletion of

fossil fuel reserves, and the challenges that situation would create for the world

economy, particularly for the transportation sector which relies almost exclusively on

liquid hydrocarbon fuels derived from crude oil. Of all the alternative energy sources

proposed for the transportation sector, none has gained as much traction (or publicity)

as hydrogen. The ultimate aim of the hydrogen infrastructure is to feed fuel cell vehicles

(FCVs) which – instead of burning fossil fuels to generate the kinetic energy of motion –

would combine hydrogen and oxygen (the latter from the air) to produce electricity and

water: the former can be used to drive an electric motor, while the latter can be

harmlessly exhausted into the atmosphere.

Molecular hydrogen is not found naturally on Earth: it needs to be produced. The

separation of the gaseous compounds from the hydrogen is a more delicate task and is

very important as they might impair the performance of the polymer electrolyte

membrane (PEM) fuel cells that would power FCVs. It is therefore crucial to remove

these contaminants from the reformate before introducing it to a PEM fuel cell.

Working of Hydrogen Pump:



A fuel cell is operated at low currents as a hydrogen pump whereby a mixed

stream of H2 and CO2 is introduced to the cell at the anode inlet, and a nitrogen stream

is introduced at the cathode inlet. When a current is applied to the cell, the chemical

potential difference of hydrogen between the anode and cathode generates a voltage.

H2 from the anode is pumped across the membrane to the cathode, yielding H2 of a

very high purity at the cathode outlet: this H2 can then be used in PEM fuel cells. This

setup can be tested at various gas compositions and various temperatures and current

supply. Experiments that simulate hydrogen pumping fuel cell stacks are also carried

out.

The second two components are the two electrodes, the anode and the cathode,

whose job is to transfer electrons either to, or from, the chemical species reacting at

their interface. The electrodes can be made of any conducting material – the layer that

catalyzes the dissociation of gases at the three-way interface of gas, catalyst, and

electrolyte membrane is part of the electrode (the catalyst at both anode and cathode is

platinum supported on carbon or Pt/C).

The final component is the electrolyte membrane itself which permits the transmission

of electrons from one compartment to another (and hence, of electric current to an

external load). The most commonly used membrane is Nafion®, originally produced by

DuPont. Nafion® is a sulfonic acid ionomer which serves as a conductor of protons.



An ideal PEM would not conduct any electrons across the membrane, would not

permit the crossover of gases from the anodic compartment to the cathodic

compartment (or vice versa), and would resist the harsh environments at either

compartment (the oxidizing environment at the anode and the reducing environment at

the cathode). However, this membrane must be nearly fully humidified to minimize its

internal resistance, allowing it to operate at optimum capacity. The membrane is

sandwiched between the two electrodes to construct a ‘membrane electrode assembly’

or MEA.

At the anode, hydrogen gas dissociates into protons and electrons. The former is

transported across the electrolyte membrane to the cathode, while the latter is

transported to the cathode terminal through an external circuit that passes through an

external load. Reaction below highlights the oxidation reaction that occurs at the anode:

𝐻2 → 2𝐻+ + 2𝑒−

Hydrogen gives away 2 negatively charged electrons and becoming positively charged.



Hydrogen Pumps:

There are several applications for hydrogen pumping using PEM fuel cells. The use of

such cells as electrochemical hydrogen compressors has been studied, where the large

pressure difference between the anodic and cathodic compartments allows for pumping

from one side to the other with high process efficiency, high purification capacity, and

low power requirements. More recently, PEM fuel cells have been combined with

electrochemical pumps (also PEM fuel cells) for the purpose of hydrogen recirculation in

fuel cell stacks. The third major application is their use as stream purifiers or as

hydrogen separators. The idea of using PEM fuel cells as hydrogen pumps for the

purpose of purification of mixed streams was pioneered in the 1980s by Sedlak.

However, the amount of literature dedicated to the subject is limited, and the idea has

only recently been revived.



Channel Design:

Thermal Spraying of the plates after creating channels:



Assembly of the Hydrogen Purifier:

Specifications of the products used:

MEA: (Ion Power)

Type: N117

Active area: 10 cm by 10 cm

Total area: 17.8 cm by 17.8 cm

Anode and Cathode Catalyst: 0.3mg/sq.cm Pt (40 % C)

Gas Diffusion Layer: ( Nuvant Systems )

ELAT LT 1400 double-sided: A woven carbon cloth gas diffusion layer with a carbon



micro porous layer on both sides.

Gaskets: (McMaster)

Extreme-Temperature Silicone Rubber, 1/32" Thick, 12" X 12", 50A Durometer.

Purifier Plate Dimensions:

6 inch by 6 inch Stainless Steel with flow area of 10 cm by 10 cm.

Thickness: 1/8th of an inch.

End Plate specifications:

12 inch by 12 inch Aluminium.

Thickness: ½ an inch.

Setup Requirements:

Fair comparison was carried over between testing of all the plates by keeping the other

parameters same and altering the flow plates only.

Voltage: Any voltage difference occurred in the setup is acceptable.

Current: Not more than 1 Amps.

Inlet gas: Same mixture (3:1 H2:N)

Inlet pressure: 5 psi.



Sample size: Same (1 ml)

GC Sensitivity : 1: 20

GC settings : Same

Injector: 150˚C, Detector: 200˚C, Column:90˚C, Constant flow rate.

Reader movement: 1 mm/sec

Time measured: 30 minutes right after passing the current.

Torque: 60 inch pounds.

Tools and apparatus: Remains the same

Note: The amount of current passed plays a major role in the functioning of the

purifier either positively by increasing purifier performance or results negatively beyond

an extent by causing damage to the MEA by blowing it up.



Criteria of judgment:

Implicit reference:

The measurement of pressure in the pure hydrogen outlet is an implicit

indication or reference of the design of the plate.

Better the plate design greater the retention time.

Greater the retention time increased availability of time, for the inlet dirty

gases to react with MEA. Hence, higher the pressure attained in the pure

hydrogen outlet side

Explicit reference:

The readings of the GC (Gas Chromatography) are an explicit reference to the

design aspect of the plate.

In the dirty gas outlet, if any hydrogen is found or detected, it is due to the lack of

time the inlet gases were prone to.

Insufficient time for the gases to react with MEA or for the proton exchange

reaction causes into direct bypass to the dirty outlet without taking part in the

actual reaction.

So when a sample of the dirty gas outlet is analyzed on the GC, at a specific time,

it should show less percentage of hydrogen content.

Better plate design minimal hydrogen content in the dirty outlet.



Plots and figures:

Pressure readings of 1 pattern:




GC readings:

Pure Hydrogen Sample Test:

Mixture of 3:1 H2 – N:



1 pattern plate:

3 pattern plate:



5 pattern plate:

7 pattern plate:



Conclusion:

I conclude my project presentation with the point that the 7 flow pattern plate

design came out to be the best out of the other available options that were tested.

Higher the number of flow lines, more efficient the assembly is. The reason being

that it accumulates or creates higher pressure in the pure hydrogen outlet for the

same given time. Thereby, resulting in more production of desired gas (pure H2) at a

faster rate.

Result came out as expected.


senior project report

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