Papers by Ala'a Al-Falahat
Visualization of water accumulation in micro porous layers in polymer electrolyte membrane fuel cells using synchrotron phase contrast tomography
Case Studies in Chemical and Environmental Engineering
Journal of Applied Crystallography
A systematic study has been carried out to investigate the neutron transmission signal as a funct... more A systematic study has been carried out to investigate the neutron transmission signal as a function of sample temperature. In particular, the experimentally determined wavelength-dependent neutron attenuation spectra for a martensitic steel at temperatures ranging from 21 to 700°C are compared with simulated data. A theoretical description that includes the Debye–Waller factor in order to describe the temperature influence on the neutron cross sections was implemented in the nxsPlotter software and used for the simulations. The analysis of the attenuation coefficients at varying temperatures shows that the missing contributions due to elastic and inelastic scattering can be clearly distinguished: while the elastically scattered intensities decrease with higher temperatures, the inelastically scattered intensities increase, and the two can be separated from each other by analysing unique sharp features in the form of Bragg edges. This study presents the first systematic approach to ...
Improving the cooling performance of photovoltaic panels by using two passes circulation of titanium dioxide nanofluid
Case Studies in Thermal Engineering
Journal of Applied Engineering Science
Conversion from conventional heating systems is developed to address the emission of CO2 in the e... more Conversion from conventional heating systems is developed to address the emission of CO2 in the environment, global warming, rising costs, potential shortages of fossil fuels, for all energy source alternatives available. This study reviewed the economic feasibility associated with converting the current heat source to a renewable energy source of heating swimming pools located in Jordan. Many modern heating systems techniques are proposed in this study such as solar heat collectors, heat pump and photovoltaic assisted heat pump. Solar heat collectors are a device that collects and/or concentrate solar radiation from the sun and allow for heating the water. In addition, a growing interest in photovoltaic/heat pump systems is considered, which combines photovoltaic cells and heat pump systems. Hence converting solar energy into electricity and then heat through the heat pump. The Initial and operation cost for all proposed techniques is evaluated. As a result, it is found that the be...
Emerging Science Journal, 2022
The heat exchanger (HE) is a device that is used to complete the process of heat transfer between... more The heat exchanger (HE) is a device that is used to complete the process of heat transfer between different matters without direct mixing. Therefore, it is of great importance in the transfer of energy and the completion of various energy transition processes. In the processes of HE between different energy systems, many factors influence and play a major and important role in the efficiency of transformation and exchange in forms of energy, such as the length, the material type, the exchange fluid, the surrounding environment, and many other factors. In this work, the effect of the HE length of the parallel and counter flow HEs was investigated based on the use of computer simulation programs. There was a significant impact of the exchange factors, especially the length of the HEs in both the parallel and counter-flow HEs, on the quality and efficiency of the HE and the temperature distribution. The overall evaluation shows that by increasing the length of the HE for both parallel ...
Journal of Applied Engineering Science, 2022
This paper evaluates and compares the embodied energy and embodied carbon using a Life Cycle Asse... more This paper evaluates and compares the embodied energy and embodied carbon using a Life Cycle Assessment (LCA) approach for three different intermediate floor structures, all of which use prefabricated materials-cross-laminated timber (CLT), precast hollow-core concrete, and solid concrete-to decide which floor construction materials have less environmental impact for use in the construction of a semi-detached house in the UK. The Inventory of Carbon & Energy (ICE) and the Carbon Calculator tool were used to calculate the carbon footprint from "cradle to grave" to determine whether the use of a CLT solution provides improved environmental performance over the traditional concrete solutions. The carbon footprint results indicate that the use of a hollow-core precast concrete floor system emits less carbon than the other two systems, although the concrete requires more fossil fuel input than the timber during the manufacturing process, so based on this, the footprint from cra...
EUREKA: Physics and Engineering, 2022
Balancing is essential in rotating machinery, which is widely employed in many technical sectors,... more Balancing is essential in rotating machinery, which is widely employed in many technical sectors, particularly in high-speed rotor-bearing systems. The mass balancing method of the hollow shaft manufactured of composite materials is investigated in this study over the whole speed range of the rotor. The main goal of the balancing technique is to generate a smooth-running machine by removing the commonality imbalance mass through the use of compensating mass unbalance. As a result, MATLAB code is created to produce a functioning mathematical model of the rotor-bearing system. The unbalanced rotor-bearing system finite element model is proposed to set the balancing mass of the composite hollow shaft at a selected speed rotor that allows minimizing the vibration response amplitude of the rotor as much as possible with minimal impact on the rest of the imbalance response within the speed range of the interest. As a consequence, this study validates the process for distributing imbalance...
Energy and exergy analyses for a combined cycle power plant in Jordan
Case Studies in Thermal Engineering, Feb 1, 2022
Energy and exergy analyses for a combined cycle power plant in Jordan
Case Studies in Thermal Engineering, 2022
International Journal of Mechanical Engineering and Robotics Research, 2021
The unbalance in rotating machines is one of the major sources of rotor damage. Therefore, provid... more The unbalance in rotating machines is one of the major sources of rotor damage. Therefore, providing information on the behaviours of the unbalance rotor shaft is necessary to avoid the early damage of the rotor shafts and improve the efficiency of the rotating machines. For this purpose, the dynamic behaviour of a rotating composite hollow shaft is investigated by analyzing the vibration of a homogenized finite element beam model contain a flexible composite hollow shaft and a solid disc through identifying the relationship between the rotor unbalance response with both magnitudes of the imbalance and the rotating speed of the rotor as a function of frequency response. The Campbell diagram and stability analysis of the composite shaft is investigated.
Neutron imaging, specifically radiography and tomography, is nowadays widely used technique for n... more Neutron imaging, specifically radiography and tomography, is nowadays widely used technique for non-destructive investigations of materials and is commonly utilized for various applications in the field of engineering science and technology. The neutron imaging experiments presented in this work were conducted at the neutron imaging facility CONRAD-2 and at the ESS test beamline instrument V20 at the neutron source BER-II. A virtual model of the instrument is used to analyse the performance of instrumentation, to optimize the existing instrument components and to compare the results of real experiments with Monte-Carlo ray-tracing simulations. Experimental data of a double-crystal monochromator that is widely used at steady state neutron sources is investigated and compared to neutron ray tracing simulations. The influence of crystal mosaicity on neutron flux and beam size are reported for the utilized setup and the resulting wavelength gradients along one direction. Moreover, a novel neutron radiographic technique for Bragg-edge imaging experiments utilizing the wavelength gradient was developed. Furthermore, a technique to enhance the wavelength resolution of a monochromatic neutron beam at the CONRAD-2 instrument is applied based on a deconvolution algorithm using a Fourier selfdeconvolution method. This method depends only on the narrowing of the spectrum band and can be performed by selecting the optimal value of the full bandwidth at half-maximum (FWHM) parameter, which corresponds to the resolution of the instrument that acquired the spectrum. In order to investigate the potential advantage of the deconvolution technique Bragg-edge transmission spectra of different steel samples were recorded by the time-of-flight (TOF) technique at the ESS test beamline which provides much better resolution (below 1% ΔE/E) than the double-crystal monochromator (approximately 2.5% ΔE/E). This technique is very useful for microstructural analyses based on Bragg-edge spectroscopy. In order to quantify Bragg-edge spectra of samples under in-situ heat treatment, the transmission spectrum of a martensitic steel was determined by experiments at different temperatures ranging from 21 °C to 800 °C. The evaluation of the spectra proved that the height of the Bragg edge changes with the Debye-Waller factor. The diffracted intensity decreases with increasing Kurzfassung Neutronen-Bildgebung, insbesondere Radiographie und Tomographie, ist mittlerweile eine fest etablierte Methode für zerstörungsfreie Materialuntersuchungen mit einem großen Spektrum verschiedenster Anwendungen in ingenieurwissenschaftlichen und technologischen Bereichen. Die in dieser Arbeit gezeigten Messungen wurden am Neutronen-Imaging-Instrument CONRAD-2/V7 sowie an der ESS Testbeamline V20 am Forschungsreaktor BER II durchgeführt. Ein virtuelles Modell der Beamlines wurde erstellt und genutzt um die Leistungsfähigkeit der Instrumentierung zu analysieren, die vorhandenen Komponenten zu optimieren und reale Messergebnisse mit Monte-Carlo Ray-Tracing Simulationen zu vergleichen. Experimentelle Daten eines Doppelkristall-Monochromators, der üblicherweise an kontinuierlichen Neutronenquellen eingesetzt wird, wurden untersucht und mit entsprechenden Ray-Tracing Simulationen verglichen. Der Einfluss der Kristallmosaizität auf den Neutronenfluss und auf die Strahlgröße im genutzten Setup wird dargelegt und der resultierende Wellenlängengradient wurde bestimmt. Darüber hinaus wurde eine neuartige Methode entwickelt neutronenradiographisch diesen Wellenlängengradienten auszunutzen, um Bragg-Kanten-Experimente durchzuführen. Auf der anderen Seite wurde mittels eines Entfaltungsalgorithmus im Fourierraum die Wellenlängenauflösung der Messungen mit monochromatischem Neutronenstrahl am CONRAD-2 Instrument erhöht. Diese Auswertemethode basiert auf einer Fitting-Prozedur, die die spektrale Auflösung des Instruments berücksichtigt. Um die möglichen Vorteile dieser Entfaltungstechnik zu untersuchen, wurden Transmissionsspektren von Bragg-Kanten mittels Flugzeitspektroskopie an der ESS-Testbeamline (1% ΔE/E) sowie mittels Doppelkristall-Monochromator am CONRAD-2 (2.5% ΔE/E) aufgenommen und verglichen. Diese Technik ist sehr nützlich für Mikrostrukturanalysen, die auf Bragg-Kanten-Spektroskopie basieren. Um die Spektren der Bragg-Kanten während einer Temperaturbehandlung quantitativ zu studieren wurden Transmissionsspektren von martensitischem Stahl bei Temperaturen zwischen 21 und 800°C aufgenommen.Die Auswertung der Spektren ergab, dass sich die Höhe der Bragg-Kanten entsprechend dem Debye-Waller Faktor ändert. Die gestreute Intensität nimmt mit steigender iv Temperatur ab. Zusätzlich reduziert eine einsetzende Phasenumwandlung den Volumenanteil der martensitischen Phase. In der Neutronen-Bildgebung beeinflussen Hinterleuchtungseffekte im optischen Detektorsystem mitunter ganz erheblich die ermittelten Transmissionswerte, was zu größeren Messfehlern in den errechneten Schwächungskoeffizienten und zu Bildartefakten führen kann. Daher ist eine Korrektur dieses Hinterleuchtens wünschenswert. In dieser Dissertation wurden diese Effekte mittels Experimenten am CONRAD-2 Instrument durch Variation der abgedunkelten Detektorfläche sowie Variation der Stärke der Abdunkelung untersucht, und ein Korrekturprozedur vorgeschlagen. v Contents 1 Introduction .
Correction approach of detector backlighting in radiography
Review of Scientific Instruments, 2019
In various kinds of radiography, deficient transmission imaging may occur due to backlighting ins... more In various kinds of radiography, deficient transmission imaging may occur due to backlighting inside the detector itself arising from light or radiation scattering. The related intensity mismatches barely disturb the high resolution contrast, but its long range nature results in reduced attenuation levels which are often disregarded. Based on X-ray observations and an empirical formalism, a procedure is developed for a first order correction of detector backlighting. A backlighting factor is modeled as a function of the relative detector coverage by the sample projection. Different cases of sample transmission are regarded at different backlight factors and detector coverage. The additional intensity of backlighting may strongly affect the values of materials' attenuation up to a few 10%. The presented scenario provides a comfortable procedure for corrections of X-ray or neutron transmission imaging data.
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Papers by Ala'a Al-Falahat