Catálogo de publicaciones - revistas

<jats:p>Estimating solar radiation is an imperative requirement for solar energy development in Jordan. In this paper, a quantitative approach, based on Artifiial Neural Network, was developed for estimating the annual global solar radiation of three Jordanian cities: Amman, Irbid and Aqaba. Thse cities are currently witnessing huge development and increasing demand for energy supply. Using a set of known meteorological parameters, two Artifiial Neural Network (ANN) models with diffrent architectures, called case 1 and case 2, fed with three types of learning algorithms for data training and testing, were designed to identify the optimum conditions for obtaining reliable and accurate prediction of the solar radiation. Th results showed that model case 1 performed generally better in terms of predicting the annual GSR (96%) compared to model case 2 (95%). Furthermore, the algorithms LM and SCG in general, ensured the highest effiency in training and testing the data in the designed models compared to the GDX algorithm. Threfore, model case 1, designed with one of these two algorithms, is selected as the optimal model design that is able to compute with high accuracy the annual solar radiation for the three studied cities.</jats:p>

<jats:p>The solid oxide fuel cell (SOFC) is considered extremely suitable for electrical power plant application. Both high temperature (HT) and intermediate temperature (IT) SOFC performances are investigated using models which are built in Aspen customer modeller. Moreover, this paper introduces a new simulation software, called Al-Nour V.1.0-2012 software application. The interface of Al-Nour V.1.0-2012 software was mainly implemented based on the educational theory of User’s Split Attention, that is; the entire software works with only one screen for all operations without any scrolling (user-friendly interface). This application reflects the fact that Al-Nour software does not require the user to have any previous training. The performance of HT-SOFC and IT-SOFC models is evaluated and compared using both software applications . The simulation results show that, the cell voltage value increases by raising the operating pressure, operating temperature, and hydrogen partial pressure. The electrical power output value from the SOFC is increased simultaneously by increasing the current density . Furthermore, the IT-SOFC has a higher cell voltage than the HT-SOFC.</jats:p>

<jats:p>A mathematical model based on the momentum, continuity and energy balance equations was developed to simulate the behavior of the air flow inside the solar chimney system. The model can estimate the power output and performance of solar chimney systems. The developed mathematical model is validated by the experimental data that were collected from small pilot solar chimney; (experiment was presented in part I). Good agreement was obtained between the experimental results and that from the mathematical model. The model can be used to analyze the solar chimney systems and to determine the effect of geometrical parameters such as chimney height and collector diameter on the power output and the efficiency of the system</jats:p>

<jats:p>A good estimate of the cooling load is one vital aspect for achieving the optimal level of comfort and energy effiency in buildings. Due to its relative simplicity, the Cooling Load Temperature Diffrence (CLTD) method is still used both in education and industry for cooling load calculations. However, one downside of using this method is the limited number of walls and roofs which do not represent effctively all commonly used wall and roof constructions. In this research, a transient heat transfer model was developedto fid the (CLTD) values, for the most common external walls of buildings that have widespread use in Tripoli, Libya. Th Finite diffrence method was used to solve the governing partial diffrential equations with appropriate initial and boundary conditions. A MATLAB program has been developed and used to solve the system of algebraic equations produced by applying the fiite diffrence method to the governing diffrential equations. A comparison has been made between the computed results and ASHRAE CLTDvalues. At standard conditions specifid in ASHRAE handbooks for the same wall with a default composition, a reasonably good agreement was found between computed and ASHRAE CLTD values for this wall. CLTD values have been generated for three diffrent types of walls; Hollow concrete block, Limestone block, and Hollow brick. With these values, the cooling load calculation of buildings can be easily and manually performed with more accuracy. It is also concluded from the transient analysis that the limestone block walls provide the best therm.</jats:p>

<jats:p>Recently, the signifiant increase in energy consumption to provide thermal comfort in Libyan buildings, has increased the dependence on mechanical systems and non-renewable resources. Threfore, there have been effrts, particularly by the governmental authorities, to search for solutions to improve buildings in terms of their thermal performances, in order to reduce high energy consumptions. Th aim of this research is to analyze and determine certain passive design strategies for residential buildings in Tripoli-Libya, by using the analysis program Autodesk Ecotect®, to reduce energy consumptions and provide thermal comfort. By the use of this program, issues such as; best possible orientation, loads of heating and cooling, thermal mass, along with the direct effcts of building materials and the importance of window sizes on thermal comfort were analyzed, based on the designed typical Libyan residential building model.The results of the study were analyzed and guidelines were developed to enhance the energy performance of residential buildings in Libya. Th fidings of this study show that the proper orientation of the building and effctive use of insulation materials can provide a 60% increase in thermal performance. Moreover, the results of evaluation on thermal comfort level by using the PMV method showed that, together with the necessary adjustments, the building would provide thermal comfort for its users.</jats:p>

<jats:p>In this work, hourly measurements of global solar irradiances obtained from a pyranometer and direct normal irradiances obtained from sunshine duration sensor are assessed through an extensive quality control procedure and statistical analysis on the measured and derived solar parameters for a semimountainous location using data from the last fie years (2016-2020). This information and the method suggested concerning the solar energy capture systems and energy efficiency is useful for engineers who can therefore take knowledge of the local radiation levels. Furthermore, the direct horizontal irradiance canbe easily calculated and the diffuse component can be estimated from the difference of global and direct horizontal irradiances. Monthly mean hourly values of the radiation components are also estimated and shown through isolines diagrams. Representative values of global direct and diffuse irradiances for different times of the year and different hour of the day can be easily read from these diagrams. Simultaneously, a similar analysis is carried out over various solar indices estimated on both an hourly and daily basis. The derived solar indices are the clearness index for global, direct, and diffuse radiation as well as the diffuse and direct fractions from global radiation. The interrelationships between the said indices are also examined.Additionally, the BRL (Boland-Ridley-Lauret) diffuse fraction model which is a multiple predictor logistic model was tested and can be used to estimate the diffuse and later the direct radiation component. The model is a function of clearness index (kt), the apparent solar time (AST), the solar altitude (αs), the daily clearness index (KT) and persistence parameter ψ which is an average of both a lag and lead of the clearness index. The outcome of the model shows that it can be used to estimate successfully the diffuse radiation.</jats:p>

<jats:p>Solar water heaters have been in use for decades in many countries in the world that have less favorable climatic conditions for solar energy as compared with Libya. However, still there is no usage of such technologies in the country. This could be attributed to many factors including, among others, lack of clear policy and/or serious plans to establish such technology, cheap prices of conventional energy, and lack of environmental awareness.&#x0D; The Center for Solar Energy Research and Studies (CSERS) of Libya has developed an excellent research and development program on a national scale for domestic solar water heating systems. The national program started in the early 1990’s aiming at increasing publicawareness. The program utilizes different ways such as pilot projects, studies, workshops, and reports to convince people and decision-makers of Libya about this subject and its benefits.This paper attempts to suggest a strategic plan (win-win situation between government and people) for encouraging and helping widespread (replacement) of solar water heaters nationwide based on economic and environmental pointers in favour of the replacement. Th suggested strategic plan is to provide 25% of existing houses in 2013 with solar water heating systems by 2022, with a governmental subsidy of up to 65% of the system cost. The study has shown that every L.D. paid by the government will return with at least 2 L.D. after 10 years of investment without considering the money saved from the fuel savings, powerplant installations to fulfill the demand, and the environmental benefits.</jats:p>

<jats:p>A non-imaging solar concentrator system of reflecting surfaces redirects the solar radiation from the source to target (receiver). This work is focused on a 2-D elliptical hyperboloid geometric design of static solar collectors, though many design concepts and procedures for 2-D static solar collector is discussed in this paper. Based on the general equation for a solar concentrator, parameters vary slightly to determine the optical efficiency. 2-D MATLAB code is written to obtain the different shapes of the concentrator. The resultsof 2-D hyperboloid concentrator (2-DHC) has been reported. The optical efficiency, effective concentration ratio, receiver major axis and concentrator height have been investigated through ray trace analysis. The optimisation of the concentrator profile and geometry is also carried out, based on the geometrical concentration ratio. The maximum optical efficiency is found to be 51% and the maximum acceptance angle of ±60° was achieved</jats:p>

<jats:p>Numerous studies on the surface of the planet have focused on the role that oceans play in the increase in temperatures brought on by climatic changes. This study has primarily emphasized the long-term warming of the Atlantic Ocean and how it affects the seasonal temperature changes of the Mediterranean Sea as a whole as well as its constituent western, central, and eastern areas. In the fall and summer, a substantial positive connection of roughly (Pearson correlation r= 0.69) and (r=0.65), respectively, between the entire Mediterranean Sea and the AMO is evident, but this correlation declines in the spring and winter. Positive correlation increases in the western portion of the Mediterranean and diminishes in some areas as we move closer to the eastern Mediterranean; it reaches a maximum of (r=0.61) to (r=0.57) in the fall and summer seasons, respectively, and declines in the spring and winter. According to the findings, there is a noticeable increase in water temperature in the fall and summer, particularly in the western Mediterranean, which is influenced by AMO.</jats:p>

<jats:p>Hydrogen constitutes an integral component within an expansive array of energy technologies poised to facilitate the nation's transition towards achieving a net-zero state. In additional, this endeavor involves harnessing regional resources judiciously, thereby fostering equitable and sustainable growth. The strategic development and utilization of hydrogen technologies necessitate a nuanced approach, encompassing an assessment of diverse technologies spanning various sectors especially power sector. Such a meticulous strategy aims to forge the most efficacious, cost-effective, and sustainable pathways, underpinned by the discerning adoption of these technologies in the market. The article delves into the intricate relationship between hydrogen and fuel cell technologies, shedding light on their combined impact on the evolving landscape of electricity generation. A particular focus is placed on the integration of variable renewable energy sources, elucidating how hydrogen serves as a key enabler in optimizing the utilization of these fluctuating energy resources. In addition, the article encompasses various methods of hydrogen production, exploring their technological advancements and implications for achieving sustainable electricity generation. Emphasizing the significance of technology development in the hydrogen sector, the paper delves into the potential of hydrogen production methods and their implications for advancing sustainable electricity generation. In essence, the article navigates the trajectory of the hydrogen sector's evolution within the broader context of electricity generation, offering valuable insights into the ongoing developments, challenges, and opportunities. By addressing the critical nexus between hydrogen technologies and the dynamic electricity landscape, the paper aims to contribute to the discourse on the future trajectory of investments in the hydrogen sector for enhanced electricity generation. To Conclude, the United Kingdom has committed GBP 20 billion over a span of 20 years to the development of Carbon Capture, Utilization, and Storage (CCUS) facilities. Additionally, the nation has identified and shortlisted electrolysis projects totalling 408 megawatts (MW) capacity. In Korea, Hanwha Impact has achieved a significant milestone by attaining a 60% hydrogen co-firing share in an 80 MW gas turbine, representing the largest co-firing share recorded thus far in mid-to-large gas turbines. Meanwhile, Anhui Province Energy Group in China has successfully conducted trials involving the co-firing of ammonia at a 300 MW unit. The Group has plans to further extend these trials, aiming to achieve a 50% co-firing level at a 1 GW coal unit. In the United States, notable progress has been made, with a 38% hydrogen co-firing share attained in 2023 at an operational 753 MW combined-cycle power plant.</jats:p>