الفهرس 
ABSTRACT
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Abstract
Nowadays, replacing fossil fuels with a sustainable and environmentally
safe alternative energy source represents great challenges for scientists and
researchers in related areas. Hydrogen can be considered as the best candidate
for replacing the fossil fuel for its cleanliness, readily available and highly
efficient. Photo-electrochemical (PEC) water splitting system for hydrogen
production is one of the promising technology that utilizes renewable energy
(sunlight and water). However, the low efficiency of this technique is the utmost
challenge for hydrogen production.
The goal of this thesis is to study different designs of PEC reactors to
elevate the temperature of the electrolyte and consequently lower the water
splitting potential. Therefore, three different designs of PEC reactors are
developed. The first design is contained multi-junction electrodes as photoanode
and cathode. The solar irradiance enters the reactor from the right side wall and
the others walls are insulated to reduce the heat losses. In the second one, the
photoanode and cathode are separated and the solar irradiance enters the reactor
from the right side wall. For both the first and second design, a good
absorptivity glass is placed at the back of the reactor adjacent to the insulated
wall to act a storage for long wavelength. In the last design, the solar irradiance
entered into the reactor from right side and left side. In this thesis, numerical
study of governing equations in photo-electrochemical (PEC) reactor is
performed. The present models comprise of the Navier-Stokes and the
respective energy equations for electrolyte, and the radiative transfer equation
Abstract
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(RTE). Commercial software, ANSYS FLUENT 14.0 is used to solve the
governing equations using the SIMPLEC algorithm. Based on the numerical
results, the soar-to-hydrogen efficiency (𝜂���� and hydrogen volume production
rate (𝛷, are assessed.
The results have shown that the solar-to-hydrogen efficiency (𝜂���� and the
hydrogen volume production rate (𝛷 are increased as the solar flux is increased
for all three proposed designs. In addition, the second design is the best one
which achieved the maximum solar-to-hydrogen efficiency (𝜂���� and the
hydrogen volume production rate (𝛷 due to the minimum heat loss compared
with the other designs. Comparison between currently predicted results and the
previous data indicates an enhancement of solar-to-hydrogen efficiency and
hydrogen production that can be achieved with the current suggested designs.