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In this paper, a new design to enhance the thermal performance of residential water heaters is suggested and investigated. The new design consists of using a mixer inside the water tank driven by electrical power. To proceed, experimental measurements are made by using thermocouples implemented in a water heater to study the thermal behavior. It is proved that the mixer could reduce the heating time about 20 min to heat water from 25 °C to 70 °C. In addition, the temperature homogeneity is also studied and it was shown that the temperature without the mixer could not be homogeneous within the water volume. [ABSTRACT FROM AUTHOR]

Abstract The demand for reducing fuel consumption and mitigating exhaust fumes accountable for the greenhouse effect push toward developing efficient energy recovery systems. Optimizing the heat recovery process can be achieved by adding multi-recovery stages. In this frame, the present work suggests a new multi-stage recovery system for heating water and air and generating electricity. The concept of the system is applied to the exhaust gases of a chimney. A complete thermal modeling of the system is drawn. Then a case study is carried out for three different fed fuels (diesel, coal, wood). The results show that when diesel is used water temperature achieved 351 K and 240 W electric power is generated. Moreover, a 0.16 m2 heat recovery heat exchanger area is required to heat air to 363 K at an air flow rate of 0.0076 kg/s. Such system can recover up to 84% of the energy lost to the environment when wood is utilized as a fed fuel. [ABSTRACT FROM AUTHOR]

The current tendency in energy domain is to reduce fuel consumption in favor of sustainable energy approaches. In this frame, the present work suggests an efficient way of heat recovery from boilers using concentric tube. The motivation behind the suggested concept is that it could be considered the cheapest, easiest to construct and simplest to use among all the existing heat recovery systems. In other words, the goal is to suggest a technique that could be utilized by a wider range of users regardless their technical level. Another advantage of the proposed concept is that is can be applied even on small scale boilers. With this in mind, a numerical tool is also developed allowing to make pre-studies to optimize the geometric parameters such as diameters and length, as well as to perform post-studies that allows to optimize operational parameters such as flow rates and fluids configurations. Furthermore, an experimental study is carried-out to validate the numerical results of the adopted heat exchanger. It was shown that water can be heated up to 100 °C depending on the flow rate and that the recovered heat increases through a rational function. [ABSTRACT FROM AUTHOR]

In the recent years Green to Green Energy Systems have gain tremendous interest because they are pollution free systems. In this frame, the present paper aims at investigating a Green to Green system coupling Photovoltaic, Wind and Fuel Cell. Furthermore, an analysis procedure is developed allowing to find the optimal configuration of coupling by assessing the output power in terms of the system parameters. Moreover, a case study on Lebanon is considered where three different regions that are Dahr El-Baidar, Klaiaat Akkar and Rayak Bekaa are studied. Results shows the flexibility and strength of the suggested procedure. Indeed, it has been shown that for Dahr El-Baidar it is suggested to adopt WFC system whereas for Klaiaat Akkar hybrid PVWFC is the optimal solution and PVFC is better for Rayak Bekaa. Furthermore, an economic based optimization is carried out. It was surprisingly found that from an economic standpoint and for a land area larger than 3000 m2 Rayak Bekaa is the optimal location for WFC hybrid system. • The work is performed within the frame of Green to Green (G2G) concept that combines green source to green storage. • Green sources are PV and Wind Turbine whereas the green storage system is fuel cell. • The developed model is applied to three different regions in Lebanon in order to find the best configuration. [ABSTRACT FROM AUTHOR]

Geothermal heat pump is an efficient application derived from geothermal energy. It exploits earth as a heat provenance to extract heat from it and heat space in winter, or it uses earth as heat sink to transform heat to it and cool the space during summer. This paper presents a parametric study to investigate the effects of inlet and outlet water temperatures and ground temperature on the length of the pipe of a horizontal geothermal heat pump system during cooling process. The type of the considered pipe is Poliplex - PE100 Series 1 – polyethylene of 16 mm inner diameter and 20 mm outer diameter. The obtained results revealed that at 30 °C water inlet temperature, 27 °C water outlet temperature and 21 °C ground temperature the length of pipe needed is 716 m. Also, the results showed that higher water inlet temperature and ground temperature increases the required pipe length; however, higher water outlet temperature decreases the needed length of the pipe. [ABSTRACT FROM AUTHOR]

The reuse or reduction of wasted heat supplies an excellent opportunity for cost saving in industrial and residential application. This paper deals with a Hybrid heat recovery system that reuses the thermal energy captured by exhaust gases to produce domestic hot water and generate electric power using thermoelectric generators (TEG). The heat recovery process is mainly affected by the temperature of exhaust gases. The effect of gases temperature on the performance of the system - water temperature and power generated - is studied including different residential applications. It shows that as the exhaust gases temperature increase the heat rate, water temperature, and power generated increases. [ABSTRACT FROM AUTHOR]

Researchers are continually striving to improve the efficiency of photovoltaic panels which contain solar cells that convert light energy to electrical energy. The objective is to improve photovoltaic (PV) efficiency by maintaining it below maximum allowable temperature. Accordingly, the excess in heat must be dissipated efficiently in order to avoid excessive high temperatures, which have an adverse effect on the electrical performance of the cell. Therefore, in this paper an experimental study is presented to enhance the performance of PV panels using Aluminum finned plate, and cooling under natural convection. The use of heat sinks has been conducted to address this problem by using an optimum design of Aluminum finned plate. The results show that the use of an Aluminum finned plate has increased the solar to electrical conversion efficiency by 1.75%, and the output power by 1.86 Watt. [ABSTRACT FROM AUTHOR]

In the last decade, studying of thermal energy storage systems using phase change material (PCM) in the field of building has been increasingly developed. Indeed, it decreases the energy consumption used for indoor heating system while maintaining maximum thermal comfort for the occupants. This paper presents a study on application of white petroleum jelly, which is used as a phase change material, with an electrical under floor heating system. To proceed, a prototype of a well-insulated house is constructed. An experimental study was carried out in a relatively cold weather to investigate the thermal behavior of using phase change material. Results show that at an average ambient temperature QUOTE of 14℃ the electrical consumption was shifted by an average of 6 hours due to the latent heat stored in PCM. [ABSTRACT FROM AUTHOR]

The current work aims to present systematic information about encrusting fouling bryozoan fauna collected from Hurghada, Egyptian Red Sea. During September 2015, scraped fouling samples were collected from beneath the jetty of the National Institute of Oceanography and Fisheries, Red Sea branch, Egypt. Five species of encrusting bryozoan are recorded in the present study. These are Celleporaria aperta , Parasmittina egyptiaca , Watersipora subtorquata , Hippopodina feegeensis and Scorpiodinipora costulata , affiliating to 5 families, which belong to the suborder Neocheilostomina. Parasmittina egyptiaca , Hippopodina feegeensis and Scorpiodinipora costulata are new records from Hurghada, Red Sea waters. Descriptions of the recorded species are given with illustrative photos as well as their geographical distribution and habitats. [ABSTRACT FROM AUTHOR]

Designing energy recovery systems that are pollution free has become a significant goal within the research community. One of numerous systems that have been proposed is Speed Bump Power Generator SBPG system that produces electrical power by utilizing the movements of commuting vehicles on highways, boulevards, and streets. When vehicles pass over a SBPG system, the system translates vertically. Consequently, a kinetic energy is produced and transferred into electrical power. In this paper, different types of SBPG systems are presented. An experimental analysis is performed on the rack-and-pinion system. Results have shown that electrical power up to 45 W generated when a mass of 80 kg is applied to SBPG system considered. Extrapolation of results confirms around 0.56 kW powers can be produced when various vehicles with different masses pass through the bumps. [ABSTRACT FROM AUTHOR]

The present work considers parametric analyses that examine the attempts of capturing heat from the exhaust gas of 500-kVA power generator. The heat capturing is performed through the use of counter flow concentric tube heat exchanger. The captured heat is utilized to heat water. Therefore, various geometrical configurations of heat exchangers are considered and supplied to heat transfer equations. Two flow-patterns are considered, flow-pattern I where the exhaust gas is streamed in the inner tube while the water is flowing in the annulus, and flow-pattern II where exhaust gas is streamed in the annulus while the water is flowing in the inner tube. The appropriate heat transfer modeling is briefly presented. It was found that the most efficient geometrical configuration is found in flow-pattern II, where water flows in the inner tube with an inner to outer diameter ratio of 0.75. The corresponding captured average heat rate of the aforementioned case is 26 kW. [ABSTRACT FROM AUTHOR]

The present paper presents taxonomical information on a small bryozoan fauna collected from the Eastern Mediterranean coast of Egypt. Eight species of benthic bryozoans are reported from the trash crop of a trawling net in the area between Damietta and El-Manzalah. These species belong to 7 genera in 7 families of the orders Cyclostomata, Ctenostomata and Cheilostomata. Four species ( Hornera sp., Nolella dilatata , Copidozoum planum and Schizomavella triangularis ) are new records of the Egyptian Mediterranean waters. All species are described and photographed. [ABSTRACT FROM AUTHOR]

Using a trawling net, samples of order Pennatulacea (Sea pens) were collected from the northern coast of Egypt. The current work aims to establish taxonomical data about this distinctive group of animals that dwell in the Egyptian Mediterranean waters. The current study presents 3 species namely; Cavernularia pusilla (Philippi, 1835), Pennatula rubra Ellis, 1764, and Pteroeides spinosum (Ellis, 1764). The first one pertains to the family of Veretillidae which belongs to the suborder Sessiliflorae; while the other two species affiliate to two families (Pennatulidae and Pteroeididae) which belong to the suborder Subselliflorae. The present records are the first from the Egyptian Mediterranean waters. A re-description supplied with full structural illustrations of the recorded species is given. [ABSTRACT FROM AUTHOR]

Background and study aims To search for an immunological parameter that may correlate with the response to interferon (IFN) treatment is very crucial. The objective of this study was to correlate the levels of C3 and C4 complement components with the response to IFN treatment in patients with chronic hepatitis C virus (HCV) infection. Patients and methods This study was conducted on 100 patients and control subjects classified into three groups. Group (I) consisted of 50 patients with chronic hepatitis C who were receiving IFN treatment and showed various responses; group (II) included 25 patients with chronic hepatitis C naive to IFN treatment; and group (III) included 25 healthy subjects matched for age and sex who served as controls. Measurement of the level of complement C3 and C4 was done by a quantitative turbidimetric test. Measurement of complement levels in group (I) was done at the end of treatment at the 48th week. Results Serum levels of C3 and C4 were found to be significantly reduced in all patients with chronic HCV infection in both groups (I and II) compared to the healthy control group (III) (p < 0.05). Moreover, chronic HCV patients treated with IFN and ribavirin had significantly lower levels of C3 and C4 compared with patients naive to IFN and ribavirin treatment. At the end of treatment, both C3 and C4 had significantly increased in responders to IFN when compared to non-responders (p = 0.025 and 0.05, respectively). There was a significant negative correlation between C3 and C4 levels and the concentration of serum alanine aminotransferase (ALT) measured simultaneously. Conclusion Higher C3 and C4 serum concentrations were found to be positively correlated to the end-of-treatment response in patients with chronic HCV infection treated with IFN and ribavirin. [ABSTRACT FROM AUTHOR]

Abstract: Based on qualitative samples collected from different habitats, in three sampling occasions through the years 2009–2010, the current work aims to investigate the diversity and spatio-temporal distribution of macro-invertebrate assemblages at spring flows of Tsuya Stream, Gifu Prefecture, central Japan. A total of 2889 individuals representing 65 taxa of invertebrates were collected from the two investigated sites (inlet and the main-channel). Thirty-two new taxa were recorded which include 1 Turbellaria, 8 Oligochaeta, 1 Hirudinea, and 22 Insecta comprising 1 Ephemeroptera, 1 Odonata, 4 Trichoptera, 1 Coleoptera and 15 Diptera (1 Simuliidae and 14 Chironomidae). Aquatic insects constituted about 69% and 82% of the total recorded taxa and individuals, respectively. More individuals and taxa were recorded at the inlet site with dipterans being predominant at both sites. Muddy habitat of the inlet site sustained more individuals than submerged macrophyte and gravel habitats although the taxon richness did not exhibit clear differences. Moreover, neither of the studied habitats (macrophyte and gravel) in the main-channel site showed a clear tendency to collect more taxa nor individuals. Of the non-insect groups, Mollusca and Oligochaeta exhibited more individuals in the main-channel site, and meanwhile Crustacea showed higher number at the inlet site. Ephemeroptera and Chironomidae (Diptera) indicated higher numbers in the inlet site and Trichoptera showed more individuals at the main-channel site. The temporal distribution of macrobenthic fauna showed a narrow range of variation (range of taxon richness: 40–47, individual number: 934–1001) with more taxa in July 2010. The estimated taxon richness of the mother community by Preston and Morisita methods also revealed higher values in July 2010. However, taxa abundance curve of chironomid larvae showed a distinct pattern approximated by the Random Fraction model of community organization. [Copyright &y& Elsevier]

Abstract: We report here experimental results focused on the optimization of vehicle underhood cooling module. These results constitute the basis for a new approach of controlling the cooling module positioning according to the engine energy requirements. Measurements are carried out on a simplified vehicle body designed based on the real vehicle front block. We report here velocity and temperature measurements by Particle Image Velocimetry (PIV), by Laser Doppler Velocimetry (LDV) and by thermocouples. The underhood of the simplified body is instrumented by 59 surface and fluid thermocouples. Measurements are carried out for conditions simulating both the slowdown and the thermal soak phases with the fan in operation. Different fan rotational speeds, radiator water flow and underhood geometries have been experimented. The ultimate aim is to apply the new control approach to a real vehicle so as to reduce the energy delivered to the pump and compressor and therefore to reduce the vehicle fuel consumption. [Copyright &y& Elsevier]

Abstract: The present paper reports a numerical investigation of spatial optimization of heat-exchanger by acting on its positioning in the vehicle’s cooling module. This analysis also elucidates how to act on the different parameters influencing heat-exchanger performance in order to optimize their functioning. A two-dimensional computation code permits optimizing the performance of the cooling module by positioning different heat exchangers, in both the driving and stop phases of the vehicle. The ultimate aim is to apply new control approaches to real vehicles so as to reduce pump and compressor energy consumption and thus fuel consumption. Compared to a reference “in-series” configuration of the cooling module HXs (in which the different HXs are superposed in the airflow direction), an “in-parallel” configuration (in which the different HX surfaces are in a row with respect to the air flow direction) increases the thermal power of the HXs by 4.4% and decreases the pressure losses by 0.9%. [Copyright &y& Elsevier]

Abstract: Using the basic equations for modeling heat transfer through heat exchangers, an analytical approach is developed to determining the thermal performance of cross-flow air-cooled heat exchangers as a function of the flow statistics of the upstream cooling air. A two-dimensional computational code is also developed to calculate heat-exchanger performance in relation to the airflow topology upstream of the heat exchanger induced by its integration in complex environments such as the car underhood compartment. The analytical and numerical results show satisfactory agreement: the mean relative error in heat exchanger thermal performance determined by the numerical computation and the analytical approach is about 0.5%. [ABSTRACT FROM AUTHOR]

The present work concerns parametric analysis and case study of the performance of a newly suggested Multi Drain Heat Recovery System (MDHRS) that uses the relatively hot water of different drain sources such as the shower, the dish washer, the washing machine, and the sink simultaneously to heat/preheat residential cold water. To proceed, an appropriate thermal modeling along with its associated in-house code are developed. The heat rate error between numerical and experimental results is always below 14.2% for different inlet cold water temperatures and for different cold and hot water flow rates. The parametric analysis performed treated the effect of the hot and cold water inlet temperatures and flow rates on the performance of the system and allowed to raise practical recommendations in terms of application of the suggested concept. In the case study presented, the monthly amount of energy reduced, the monthly amount of money saved and the monthly amount of CO 2 emissions reduction are considered. It was shown that when the heat exchanger length increases from 0.2 m to 1 m, the monthly amount of reduced energy increases from 102.2 kWh to 410.9 kWh, the monthly amount of money saved increases from 13.3 $ to 53.4 $ and the monthly amount of emissions reduction increases from 72.5 kg to 291.7 kg for a drain water temperature of 25 °C for the case of Lebanon. [ABSTRACT FROM AUTHOR]

Abstract: In June 2009, WHO declared the maximum phase alert against H1N1 pandemic flu. Health care workers (HCWs) are considered a strategic target for prevention of the occurrence of H1N1 influenza since they had the greatest risk of acquiring infection. The objectives of our study were (1) identifying the uptake of influenza A(H1N1) 2009 monovalent vaccine by primary health care workers in the southern part of Cordoba, and (2) reporting of the adverse events occurred after vaccination. We followed 240 HCWs in 12 primary health care centres at southern part of Cordoba for vaccine uptake and the occurrence of adverse events. The coverage rate with H1N1 vaccine was 20.5% which was lower compared to seasonal influenza vaccination rate 44.2% in 2009. Males had higher H1N1 vaccination rate compared to females with no significant difference. Senior HCWs complied more with seasonal influenza vaccine while this finding was not consistent with H1N1 vaccination. Multivariate analysis showed that the only independent variable that affected H1N1 vaccine was the compliance to the seasonal flu vaccine in the past three years with OR 5.1 and 95% CI (2.4–10.8). Adverse events occurred among 26.5% of those who complied with H1N1 vaccination. Those were local pain, irritation and induration at site of injection (38.5%), fever (15.4%), fever cough and rhinorrhea (15.4%) generalized pain and lumber pains (23.1%). The low vaccination rate in this study is consistent with previous studies done in many parts of the world and in Spain. Further studies should be done to explore the factors that hindered the uptake and resistance of HCWs to vaccination to H1N1 vaccine. [Copyright &y& Elsevier]

Sharing of renewable energy and reduction of conventional energy consumption as an attempt to ameliorate environmental issues such as global warming has become the main concern for current developing scientific engineering research. Moreover, with the drastic increase in cooling and heating requirements in the building sector worldwide, the need for suitable technology that enables improvement in thermal performance of buildings is addressed. Utilizing phase change materials (PCMs) for thermal energy storage strategies in buildings can meet the potential thermal comfort requirements when selected properly. The current research article presents an overview of different PCM cooling applications in buildings. The reviewed applications are classified into active and passive systems. A summary of the used PCMs and their respective properties are presented as well. Primary results of the studied systems are demonstrated to be efficient in reducing indoor temperature fluctuations and energy demand during cold seasons along with the capability of triggering load reduction or shifting. • A state-of-the-art review on cooling applications of PCM in buildings. • Cooling PCM applications are classified as active and passive systems. • PCM serves as a promising technology for energy-efficient buildings. • Combining active and passive systems can be a potential step toward NZEB. [ABSTRACT FROM AUTHOR]

The present work examines the combination of solar energy systems with Fuel cell. Indeed, fuel cells are green storage systems without any pollution effects. They are supplied by oxygen and hydrogen to produce electricity. That is why it is inescapable to find a source of hydrogen in order to use fuel cell. Several techniques can be adopted to produce hydrogen depending on the availability and the cost of the sources. One of the most utilized techniques is electrolysers. They allow to obtain hydrogen from water by several technologies among them proton exchange membrane (PEM) which is considered in this work. On the other hand, electrolysers need electrical power to operate. A green-green energy system can be constructed by using a renewable energy source to supply fuel cell trough electrolysers. A comparison between two solar systems (Photovoltaic and Parabolic Trough) coupled to fuel cell is performed. A case study on the Lebanese city of Tripoli is carried out. The study shows the performance of each of both combined systems for different parameters and proposes recommendations depending on the considered configuration. Image 1 • A green-green energy system combining solar thermal system and photovoltaic cells to Fuel cell is proposed. • A case study on the Lebanese city of Tripoli is presented. • FC-PV and FC-ST are nearly equivalent regarding the yearly produced energy. • FC-PV ensures a better minimum threshold power of 5kW. [ABSTRACT FROM AUTHOR]

One of the most challenging issues in the domain of renewable energy is the instability of produced power. To put it another way, renewable resources such as solar energy cannot provide continuous energy supply because they rely on natural phenomena that vary randomly. That said, to cover the potential lack of energy that may occur, hybrid renewable energy system can be adopted. In other terms, instead of using single renewable energy source, two different sources can be utilized in order to optimize the output power all over the year. Furthermore, complementary energy system is needed along with renewable sources, to store energy and insure the supply during shortage period. With this in mind, a Green-Green energy system can be constructed by using green storage system such as Fuel Cell to be coupled with the renewable sources. In the light of green-green energy concept, the present paper examines a triple wind-solar-fuel cell combination in the aim of overcoming the energy shortage that occurs during several months of the year. A case study on the region of Dahr Al-Baidar in Lebanon is conducted to present the advantage of the proposed system. Results show that combining wind energy system with thermal solar system allows overcoming the low power produced by solar thermal system especially in winter. For illustration 16 kW are produced by wind turbine during the month of January, by contrast the thermal solar system provides 2 kW during the same period. Nevertheless, in June thermal solar offers 17 kW and wind turbine produces 11 kW. • A smart hybrid system, combining fuel cell, wind turbine and thermal solar system is presented. • The proposed system allows maximizing the yearly produced energy by optimizing the supplied power at each period of the year. • A case study on the region of Daher Elbaidar in the east of Lebanon is considered. • The concept can be seen as a securing strategy against intermittent aspect of renewable energy sources. [ABSTRACT FROM AUTHOR]

To reduce the carbon dioxide foot print, it is unescapable to adopt an energy policy that incorporates simultaneously renewable energy systems as well as smart energy strategies such as heat recovery. In the frame of this view, a heat recovery approach is suggested. The heat is recovered from drain water. It is then utilized to enhance the performance of heat pump within two schemes. Directly by replacing the ambient air heating the evaporator and indirectly by preheating the air heated by the condenser. The suggested approach is a numerical and experimental method that, on one hand, relies on experiments to determine the temperature of the drain water and on the other hand, it uses an iterative procedure to solve the energy balance equation and the mass balance equation. To that end an in-house code is developed. It allows to evaluate the heat efficiency of the heat recovery system as well as the performance of the heat pump. It has been shown that using such system may enhance the Coefficient of Performance up to 400%. In addition, economic and environmental studies are performed to assess the economic and environmental impact of the proposed techniques. [ABSTRACT FROM AUTHOR]

In this work, a review on solar cookers is presented. This review includes principle and classification, parameters influencing the performance of a solar cooker, and energy and exergy analysis related to solar cooker systems. Moreover, an economic study is performed for different scenarios in Lebanon (home, hotel, restaurant and snack) and for several categories of solar cookers (solar box cooker, solar panel cooker, parabolic solar cooker and evacuated tube solar cooker with thermal storage). The main idea of the economic study is to estimate the payback period in function of percentage of time Pr where solar cooker is utilized, for each solar cooker and in each scenario. It was obtained that the higher dependence on solar cooker decreases payback period. Besides, environmental analysis is implemented to compute the amount of reduction in carbon dioxide emissions in the different scenarios as percentage of time where solar cooker is used varies. It was shown that the reduction in amount of carbon dioxide raised from 6.05 to 60.55 kg/month, 605.52 to 6055.2 kg/month, 399.64 to 3996.43 kg/month and from 90.82 to 908.28 kg/month in home, restaurant, hotel and snack respectively when Pr increased from 0.1 to 1. Hence, utilizing a solar cooker diminishes carbon dioxide emissions in all scenarios where P r has direct relationship with minimization of carbon dioxide emissions. [ABSTRACT FROM AUTHOR]

Abstract: The bilateral sagittal split osteotomy (BSSO) is one of the main orthognathic surgery procedures used for managing skeletal mandibular excess, deficiency or asymmetry. It is known to be a technique-sensitive procedure with high reported incidences of inferior alveolar nerve injury, bad splits and post-surgical relapse. With the increasing use of computer-assisted techniques in orthognathic surgery, the accurate transfer of the virtual plan to the operating room is currently a subject of research. This study evaluated the efficacy of computer-generated device at maintaining the planned condylar position and minimizing inferior alveolar nerve injury during BSSO. The device was used in 6 patients who required isolated mandibular surgery for correction of their skeletal deformities. Clinical evaluation showed good recovery of the maximal incisal opening and a reproducible occlusion in 5 of the 6 patients. Radiographic evaluation showed better control of the condyle position in both the vertical and anteroposterior directions than in the mediolateral direction. The degree of accuracy between the planned and achieved screw positions were judged as good to excellent in all cases. Within the limitations of this study and the small sample size, the proposed device design allowed for good transfer of the virtual surgical plan to the operating room. [Copyright &y& Elsevier]

Fuel Cells (FCs) have witnessed phenomenal improvements in operation and utilization for different stationary and mobile applications. Scaling up limitations of FCs and their integration restrictions into high energy applications because of maldistribution of the reactants' (fuel and oxidant) flow become among the major drawbacks. The relevant non-uniform electrochemical reactions may result in the FC performance degradation and decrease in lifetime. Therefore, this paper aims at introducing a comprehensive review on the advances in the methods of flow distribution in FCs. The levels in FC design either individual cell or FC stack that introduce non-uniformities are highlighted. The negative impacts on the FC performance, mainly the thermal and water management aspects, have been explicitly introduced. The consequent phenomena the FC experiences such as non-uniform heating, water flooding and membrane drying are presented. Based on the literature review, the critical insights and recommendations are provided alongside a suggestion of a cellular level flow distributor design to be investigated in future studies. • In this review, the advances in the methods of flow distribution in FCs are exposed. • The stages in the design of the fuel cell which induce non-uniformities are highlighted. • The thermal and water management aspects and the consequent phenomena are presented. • Critical insights and recommendations are given. • A cellular level flow distributor design to be investigated in future studies is suggested. [ABSTRACT FROM AUTHOR]

• A new thermal modeling of PTPVT along with an associated iterative procedure are developed. • Case studies are performed on three countries of different climates. • The highest achieved outlet temperature among the three cases is 95 °C in Lebanon. • The highest thermal efficiency is attained in UAE (51.1%). • The highest electrical efficiency is 27.9% in France. This work concerns a new thermal modeling for parabolic trough photovoltaic/thermal hybrid system along with case studies. A new thermal modeling using resistance analogy is conducted on the system, compared and validated against previous works. Case studies are performed on three countries of different climates which are Lebanon (mild climate), France (cold climate) and United Arab Emirates (warm climate) in order to study the electrical and thermal performance of the system. Results reveal that the highest achieved outlet temperature among the three cases is 95 °C in Lebanon, while the highest thermal efficiency is attained in United Arab Emirates (51.1%), and the highest electrical efficiency is 27.9% in France. Besides, environmental and economic analyses are carried out for each country to shed light on the significance of the studied system. It is observed that the payback period in Lebanon, France and United Arab Emirates is 1.4 years, 1.6 years and 1.7 years respectively, while the annual amount of alleviated carbon dioxide emissions is 72.9 t, 5.1 t and 71.1 t respectively. [ABSTRACT FROM AUTHOR]

Combining solar energy systems that lead to the maximization of the avail solar energy have become a trend during the recent years. In this context, parabolic trough collector and solar photovoltaics are combined with each other to obtain parabolic trough Photovoltaic/Thermal hybrid system which enables simultaneous generation of electricity and production of hot water. The layout and cogeneration of the system are described comprehensively in this work. The novelty of this work is suggesting a new methodology for conducting thermal modeling of this system which is the thermal resistance analogy and simulating it using iterative procedure. Parametric analysis is carried out in order to investigate the influence of Reynolds number, receiver side length and receiver tube length and absorber thickness on the thermal and electrical performance of the system. The results show that the thermal efficiency decreases with the increase in Reynolds number, where it diminishes by 8.31% and 2.12% in the laminar and turbulent flow, respectively. However, it increases by about 35% when the receiver side length augments from 0.03 m to 0.2 m, and by 0.78% when receiver tube length increases from 4 m to 20 m. On the other hand, the electrical efficiency augments with the rise in Reynolds number where it increases by 38.25% in the laminar flow and 5.78% in the turbulent flow, while it decreases by 10.5% and 2% when the receiver side length and receiver tube length increases. Furthermore, the absorber thickness has no effect on the thermal and electrical behavior of the system where both efficiencies remains almost constant (thermal efficiency of 56.46% and electrical efficiency of 25.34%) with the increase in the absorber thickness from 0.02 m to 0.2 m. • Thermal modeling for PTPVT system is proposed using thermal resistance analogy. • Parametric analysis is conducted to study the performance of the system. • Maximum system total efficiency achieved is 81.8% at Reynolds number of 10,000. • Maximum system total efficiency attained is 84.4% when receiver side length is 0.2 m. • Negligible impact of receiver tube length and absorber thickness are measured on system performance. [ABSTRACT FROM AUTHOR]

The continuous aggravation of environmental pollutions and the rapid increase in the conventional sources of energy price advocated scientists to search for solutions such as heat recovery and continual sources of energy. One of the most distinguished types of renewable energy is solar energy which is neat, free and environmentally friendly renewable energy. Indeed, there are several solar energy systems that need to be studied. At the same time, combining solar energy systems is a trend these days which aims to optimize the benefits from solar radiations. Photovoltaic/Thermal (PVT) hybrid solar system is obtained by combining solar thermal collectors and solar photovoltaics to enable a simultaneous generation of electricity and production of heat. The target of this paper is to proffer a review on PVT hybrid solar collectors which comprises the history of PVT hybrid solar systems, main concept, benefits and classifications according to various manners in addition to integration of thermoelectric generators with PVT system. [ABSTRACT FROM AUTHOR]

Heat exchanger analysis is regarded to be challenging due to the numerous parameters influencing the overall heat transfer coefficient. Errors in estimating convective heat transfer coefficients often arise from the geometric complexity of heat exchangers and varying flow regimes. The current work proposes a novel iterative method for calculating the overall heat transfer coefficients of concentric tube heat exchangers based on the Reynolds number of the two fluid streams. The approach is validated using numerical simulations performed with ANSYS-FLUENT, focusing on Reynolds numbers ranging from 4000 to 8000 for both hot and cold streams. The proposed method yields a maximum percentage of error between the CFD results and the correlation of just 1.2% for all Reynolds number combinations studied. The mean squared error (MSE) decreases by approximately 9% when 25 data points are used for the correlation fitting process compared to using only 5 data points. A comparison with existing literature correlations reveals a strong agreement within ± 5 % difference, demonstrating the accuracy and reliability of the developed correlation in predicting the overall heat transfer coefficients in concentric tube heat exchangers over the investigated range of Reynolds numbers. [ABSTRACT FROM AUTHOR]

In this paper, a review on solar drying is presented. The review comprises the main components, classifications and affecting parameters. Advantages, disadvantages and limitations of such technology are also investigated. That said, solar dryers are assessed according to three key-elements: way of air movement (passive and active), mode of transferring heat (direct and indirect, hybrid and mixed) and type of drying chamber (cabinet, greenhouse and tent). Moreover, economic and environmental studies are performed for the Lebanese case in order to assess the Payback Period (PP) and the amount of CO 2 reduction. The examined parameters are the percentage of time where solar dryer is utilized (Pr), the mass of dried food and food type. Results show that for Pr equals to 0.6, when drying 120 kg of carrots using solar dryer the amount of Saved Money (SM) is 780 $/month, PP is 10 months and the amount of CO2 emissions decreases by 6400 kg/month. [ABSTRACT FROM AUTHOR]

The electrical efficiency of a photovoltaic panel PV is highly dependent on its temperature. When the temperature of a PV increases, its electrical efficiency decreases. Using Phase Change Material PCM is one of the most promising tools nowadays to reduce and regulate the temperature of a PV panel and to increase its electrical efficiency. The current research is based on experimental studies of the effect of using pure (White petroleum jelly) and combined PCM (white petroleum jelly, copper, and graphite) on the thermal behavior and electrical performance of a PV panel. A transient energy balance is also presented to analyze the system thermal behavior and correlate it to the electrical outputs. To proceed, an appropriate experimental setup was devised and three prototypes were constructed and tested. Prototype 1 is formed from a reference case and consists of a stand, a PV panel, and an electrical circuit with a given load. Prototypes 2 and 3 are designed with a container added at the rear face of each PV panel that holds pure PCM and combined PCM respectively. It was shown that the electrical efficiency of PV panels has been increased by an average of 3% when using pure PCM and by an average of 5.8% when using combined PCM. These enhancements as well the corresponding behaviors were demonstrated by a transient energy balance approach. [ABSTRACT FROM AUTHOR]