الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Hydrogen manufacturing technologies that employ water to produce pure
hydrogen and oxygen via thermal, electrolytic, photolytic, and chemical
conversion of biomass water splitting. Due to its widespread availability water
is considered a sustainable feedstock for hydrogen production. The production
of hydrogen from water has the potential to significantly reduce the depletion
of fossil fuels and CO2 emissions. Hydrogen is produced through water
electrolysis, where an electrical current splits water into its components of
Hydrogen and Oxygen, Due to its eco-friendly production and its potential for
powering heavy industry and transport, many experts think Green Hydrogen
will become an increasingly significant energy source.
The study is divided into four chapters:
Chapter one: introduction and literature review:
This chapter include a general idea about the main properties of hydrogen gas,
importance of hydrogen as a fuel, electrolysis different techniques, different
methods of hydrogen production and storage. Literature review on electrolysis
different techniques, different methods of hydrogen production, and recent
references related to the research has been used.
Chapter two
This chapter include the electrolyzer design, components, idea of work,
measured and calculated parameters, and explement technique for
measurements of evolved gasses.
Commercial electrolysis usually consists of a number of electrolytic cells
arranged in a cell stack. The major challenge for the future is to design and
manufacture electrolysis equipment at lower costs with higher energy
efficiency and larger turn-down ratios.
A new cell is proposed based on the following system:
Cathode: stainless steel 316L (chemical resistant)
Anode: stainless steel 316L (chemical resistant)
The experimental work will have the objective of maximizing the cell
efficiency by studying the different parameters affecting the cell performance
which can be summarized in the following measured values:
a) Electrode structure and size (fixed bed cylinders aspect ratio (1:1).
b) Temperature (55, 65, 75 0C).
c) Flow parameters (flow rate for anolyte and catholyte).
SUMMARY
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d) Concentration of alkali.
e) Current density.
The cell efficiency will be evaluated through measuring the amount of
produced hydrogen gas with studying the effect of the above parameters on
energy requirements such as consumed power, energy density, ampere hour,
and KWh/kg of hydrogen gas.
The experimental apparatus used in the present study consisted mainly of fixed
bed reactor, flow circuit and electrical circuit. The reactor consisted of two
cubic compartments of plexi-glass (poly amide). The reactor is divided into
three sections: inlet section, outlet section, the working section, the inlet and
outlet sections consist of plastic pipes with valves for each section to control
the flow rate within turbulent region which assist to increase the mass transfer
coefficient. The working section consist of two cubic compartments separated
by cation exchange membrane which allow the passage of only hydrogen ions,
the anode compartment contain a fixed bed stainless steel 316L acting as
anode, while the cathode compartment consist of a fixed bed stainless steel
316L, the alkaline water solution was pumped from one storage tank to the
two half cells with very high surface area which assist to increase the mass
transfer coefficient, hydrogen and oxygen evolved under applied electrical
current, hydrogen and oxygen collected in plexi-glass storage tanks connected
to gas flow meter and pressure gauge. The electrical circuit consisted of a 12
volts D.C. power supply, variable resistance, a multi range ammeter connected
in series with the cell, high impedance voltmeter was connected in parallel
with the circuit to measure the cell voltage.
Chapter three
This chapter include measured and calculated results, the effects of different
operating conditions on electrolyzer efficiency. The effect of current density
was investigated by conducting experiments at, 4 mA/cm2
, 6 mA/cm2
, and 8
mA/cm2
. The temperature was also varied (55 oC, 65 oC, and 75 oC) which
resulted in an increase in the cell efficiency from 8.3% to 96.6%. The present
study investigates the effect of different variables on cell performance. The
different variables investigated included: solution concentration, current
density, solution flow rate, rod size and temperature. The resulting flow rate
of produced hydrogen and oxygen gas, the effect of electrolyte solution flow
rate, solution concentration, and solution temperature on cell voltage were
evaluated. The produced oxygen gas, power consumption, energy
consumption, and ampere hour capacity are calculated, and the cell efficiency
is therefore evaluated by comparing the theoretical and experimental mass
flow rates of hydrogen gas. Additionally, Elevation of electrolyte temperature
reduces energy density consumption from 732 kWh/kg of H2 to 52.9 kWh/kg,
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235
The higher efficiencies values appears at rod size 10 mm, higher
concentrations of 2 M and 1.5 M at temperature 75 0C and smaller current
density of 4 mA/cm2
and reaches96.6%, whereas the lower values (8.3% to
20%) appear at rod size 15 mm, lower concentration of 1 M, lower temperature
55 0C, lower flow rates of electrolyte solution 1L/min, and the characterization
of electrodes before and after the experiment was done using scanning electron
microscopy (SEM) examination and alloy composition elemental Mapping
which prove that low cost stainless steel 316L can be used in future work in
alkaline water electrolysis with high efficiency and will help in the reduction
of electrolysis cost rather than other Nobel metals .
Chapter four
This chapter contains the final conclusions which are approved by measured
and calculated records listed in tables (3.1) and (3.2)