Externally bonded fiber-reinforced polymer (FRP) composites are commonly used to retrofit concrete beams in shear. However, debonding failure limits the effectiveness of such a system. Mechanically anchored systems eliminate the debonding mode of failure, which maximizes the effectiveness of the retrofit system. This study investigates the effectiveness of using a modified mechanical anchor to strengthen concrete T-beams in shear. The fabrication and design details of this system are discussed. Three reinforced concrete (RC) T-beams were tested up to failure under a four-point bending test to assess the effectiveness of the proposed retrofit system. One beam was tested as a control beam, while two beams were strengthened in shear using mechanically anchored dry carbon fiber (CF) sheets. The tested beams were instrumented with conventional instruments to monitor the load, strain, displacement, and acoustic sensors to monitor the damage initiation, progression, and location. The modified mechanical anchor retrofit system increased the shear capacity by up to 22 %. The acoustic emissions (AE) monitoring of the tested T-beams was able to detect the locations of the cracks that caused the failure of the beams.

The paper proposes four hybrid storage options: battery-supercapacitor, battery-flywheel, batterypumped
hydro storage, and battery-fuel cell. A probabilistic approach based on the artificial neural
network is implemented to cover the weather uncertainty. The developed options and the approach are
combined with comprehensive eco-techno-economic optimization study. Multi-objective optimization
scenarios are investigated to reduce either/both total cost or/and greenhouse gas (GHG) emissions
considering Utopia point approach. Two new hybrid particle swarm optimization - grasshopper optimization
algorithm (PSO-GOA) methods are developed: GOA updated PSO and GOA initialized PSO algorithms.
The effectiveness of the developed optimizers and the Utopia point approach are validated.
Sensitivity analysis is performed to demonstrate the variable parameters that majorly influence the
investment costs and GHG emissions. Through numerical simulations via Matlab™, PV modules rating
power, number of wind turbines, and the load demand are the key factors that impact the eco-technoeconomic
at Qusair city, Egypt. Through the Utopia point solution, supercapacitor integrated battery
demonstrates enhancements by 42.48% and 12.92% in the GHG and levelized cost of energy (LCOE)
compared to the economic and environmental solutions. The salvage market fosters the hybrid flywheel
and pump hydro storage integrated battery options by reducing the LCOE by 44% and 51%, respectively.

An assessment of a flat plate double pass (DP) solar air heater (SAH) having V-corrugated absorber (C_SAH) and corrugated-perforated absorber (CP_SAH) via energy, exergy, economic and environmental approaches (4E) is presented experimentally. The study is performed at four different levels of air mass flow ratios inside the flat plate solar air heater with two levels of absorber plates i.e. C_SAH and CP_SAH. C_SAH and CP_SAH performance is compared with flat SAH (F_SAH) performance. The results show that F_SAH achieves the lowest daily energy efficiency values of 52.5%, 55.86%, 54.77%, and 56.7% while CP_SAH achieves the highest of 67.67%, 69.7%,71.85%, and 70.8% at SP, 1/3 DP, 2/3 DP, and DP conditions, respectively. Moreover, C_SAH and the CP_SAH achieve maximum daily efficiency of 70.58% and 71.85% at 2/3 DP condition. CP_SAH achieves average daily exergy efficiency of 0 …

An experimental study is presented on the energy and exergy assessment of integrating reflectors with an evacuated tube solar collector-heat pipe (ETSC-HP) system on its thermal energy storage. The impact of using upper, lower, and upper and lower (two) reflectors on the thermal energy storage, input energy, and energy losses, reflectors' effectiveness, and energy and exergy efficiencies is assessed. A complete thermal model that evaluates the thermal performance of the collector-heat pipe system and selects the reflectors title angles is presented. The findings show that using reflectors with ETSC-HP rises its input energy, storage energy, energy and exergy efficiencies, and reflected and radiation losses but it reduces the convection losses. Using upper, lower and the two reflectors raises the input energy to the collector by about 15.3%, 22.5%, and 37%, respectively, and the output daily storage energy by 14%, 22.1%, and 35.7%, respectively compared with the system without reflectors. The daily thermal efficiency of the ETSC-HP system with upper, lower and the two reflectors is 63.8%, 71.67% and 76.25% compared with 60.57% of the collector without reflectors. Using reflectors with the ETSC-HP raises the system thermal performance curve efficiency by about 16% relative to the collector without reflectors. Moreover, using two reflectors increases the average daily exergy efficiency by about 25.3%. Using reflectors with ETSC-HP proves its ability to raise the energy storage from the collector system compared to previous works.

In this study, an assessment based on energy, exergy, economic, and environmental approaches on a double-pass (DP) solar air heater (SAH) having pin finned absorber at different air mass ratios up and down the absorber is investigated experimentally. Four air mass ratios are considered: (i) all the air mass flow passes up the absorber and returns to pass down the absorber (DP), (ii) 2/3 of the airflow passes up the absorber and returns to mix with the remainder of air to pass down the absorber (2/3 DP), (iii) the same as (ii) but 1/3 of the air passes up the absorber (1/3 DP), and (iv) all the air mass passes only down the absorber (single pass, SP). For all mass ratios, the performance of pin finned SAH (P_SAH) is compared with that of flat SAH (F_SAH). The results indicated that the air temperature rise and energy and exergy efficiencies of P_SAH are highly greater than those of F_SAH. The highest average thermal efficiency of F_SAH is 56.7% obtained at DP flow condition, whereas the highest value of P_SAH is 65.21% obtained at 2/3 DP with an increase of 17.6% compared with F_SAH. Also, P_SAH has higher average exergy efficiency of about 34.7% compared to F_SAH. Furthermore, P_SAH achieves energy payback time (EPBT) lower than that of F_SAH, while P_SAH has higher embodied energy. The findings indicated that F_SAH at SP airflow pattern has the maximum energy cost (0.0427 $/kWh), whereas P_SAH at 2/3 DP airflow pattern achieves the minimum energy cost (0.037 $/kWh). Finally, the proposed P_SAH system appears to be more viable from exergoeconomic and enviroeconomic approaches compared to F_SAH.

Flat plate solar collector is one of the main solar collectors that has a simple structure, reliable operation, large heat preoccupation area, and low cost. Its drawback is the low heat transfer between the working air and the absorber plate. A solar air heater of V-shaped transverse finned absorber having new designed absorber plate of lateral gaps and central holes to enhance its performance is investigated experimentally at single-pass and double-pass airflow conditions. Moreover, the energy and exergy assessment of its performance was studied and compared with traditional longitudinal finned heater having the same fin surface area and construction except for the absorber plate design. The study is investigated at air mass flow rates of 0.025, 0.05, and 0.075 kg/s. Findings show that the new heater achieves maximum outlet temperature rising of 28.2 °C at 0.025 kg/s and double-pass flow. Moreover, it has an average daily energy efficiency of 88.5%, 81.88%, and 61.3% at mass flow rates of 0.075, 0.05, and 0.025 kg/s with increments of 9.4%, 13.3%, and 9.66%, respectively, compared to the longitudinal finned heater. Additionally, it achieves exergy efficiencies of 2.5%, 2.1%, and 1.7% at mass flow rates of 0.025, 0.05, and 0.075 kg/s with increments 18%, 25.7%, and 18.2%, respectively, relative to longitudinal finned heater. Furthermore, the new heater design possesses greater energy efficiency comparing to former studied SAH designs.

This paper shows an application of hybrid PV/wind energy and battery storage in the islanded area. This work’s main target allows the distributed energy resources to contribute efficiently in the economic feasibility and enhance the environmental impact of the hybrid renewable energy source. Several factors such as levelized cost of energy (COE), greenhouse gas (GHG) emissions, and loss of power supply probability are studied. A combined solution is to compromise the economic and environmental aspects via the Utopia point approach is investigated. The optimal configuration of the hybrid PV/wind along with battery-storage and diesel engine as secondary source is obtained via meta-heuristic optimizers: Genetic Algorithm (GA) and Particle-Swarm Optimization (PSO) and impartial comparison of the results with HOMER software. The results of Utopia point solution show that the PV (about 46%) and wind …

A study is presented on the enhancement of solar still (SS) performance by using chimney exhaust gases (EGs) passing through chimney channels under the still basin. The impact of the exhaust gas temperature on the SS temperature, productivity, efficiency, and freshwater yield cost is considered. The SS performance with the chimney is compared with that of conventional solar still. The study is performed under the hot and cold climate conditions of Upper Egypt. A complete transient mathematical model of the physical model including the solar still regions temperatures, yield, and heat transfer between the SS and the EGs is constructed. This model is solved by using Runge-Kutta method of fourth-order and programmed inside MATLAB software and validated using an experimental setup. The results show that the SS saline water temperature and freshwater yield rise with rising EGs temperatures. Furthermore, the impact of using EGs on the SS performance in winter is superior to that in summer, and also during the daytime is higher than that of night. Using chimney EGs at 75 °C and 125 °C enhances the daily freshwater yield of the SS by more than three times and about six times in winter, respectively, and about two and half times and more than three times in summer, respectively. Using EGs at 125 °C achieves a maximum solar still efficiency of 29.5% in winter and 49.5% in summer with an increase of 41% and 55.7%, respectively, and reduces its yield cost by 63.6% compared to conventional SS

The performance of solar air heater of having a new design tubular absorber of adjacent parallel tubes called tubular is investigated experimentally via energy, exergy, energy payback time, exergoeconomic, and enviroeconomic approaches. Moreover, the impact of utilizing porous material on the tubular heat performance is analyzed and compared to flat plate air heater at air mass flow rates; 0.075, 0.05, and 0.025 kg/s for single and double passes. Results indicate that the tubular heater has higher net energy gain, output air temperature, energy and exergy efficiencies, and smaller energy loss compared to the flat heater. Using porous material and double pass increases the output air temperature of tubular air heater by 3.4 °C and flat one by 17.7 °C at 0.025 kg/s. Moreover, utilizing porous material with the tubular heater at 0.075 kg/s enhances the energy efficiency by 3.5% and 8.9% and exergy efficiency by 8.2% and 0.9% for single and double pass, respectively. Air pumping power of the tubular heater is greater than flat but its value is very small to influence the tubular net useful energy. Finally, the tubular air heater is more effective compared to flat based on energy payback time, energy cost, exergoeconomic, and enviroeconomic parameters.

Flat plate solar collector is one of the main solar collectors that has a simple structure, reliable operation, large heat preoccupation area, and low cost. Its drawback is the low heat transfer between the working air and the absorber plate. A solar air heater of V-shaped transverse finned absorber having new designed absorber plate of lateral gaps and central holes to enhance its performance is investigated experimentally at single-pass and double-pass airflow conditions. Moreover, the energy and exergy assessment of its performance was studied and compared with traditional longitudinal finned heater having the same fin surface area and construction except for the absorber plate design. The study is investigated at air mass flow rates of 0.025, 0.05, and 0.075 kg/s. Findings show that the new heater achieves maximum outlet temperature rising of 28.2 °C at 0.025 kg/s and double-pass flow. Moreover, it has an average daily energy efficiency of 88.5%, 81.88%, and 61.3% at mass flow rates of 0.075, 0.05, and 0.025 kg/s with increments of 9.4%, 13.3%, and 9.66%, respectively, compared to the longitudinal finned heater. Additionally, it achieves exergy efficiencies of 2.5%, 2.1%, and 1.7% at mass flow rates of 0.025, 0.05, and 0.075 kg/s with increments 18%, 25.7%, and 18.2%, respectively, relative to longitudinal finned heater. Furthermore, the new heater design possesses greater energy efficiency comparing to former studied SAH designs.