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.

This paper introduces an experimental study for concentrating solar cell performance cooled by using flat heat pipe. The cell represents the heat pipe evaporator and the heat pipe condenser is cooled by using a rectangular finned heat sink. This study is investigated at various heat pipe condenser and adiabatic regions lengths and concentration ratios of the radiation intensity incident on the cell, and for forced and free convection airflow cooling through the finned heat sink. The required radiation energy supplied to the cell is provided by solar simulator. The findings illustrate that cell efficiency and output power increase with increasing the heat pipe condenser and decrease its adiabatic regions’ lengths. However, cell efficiency reduces with rising the incident radiation intensity. The heat pipe temperature increases with radiation intensity, but its maximum temperature difference does not change greatly with variation solar intensity. Cooling the cell by heat pipe increases its output power by 24.3% compared to free convection without utilizing heat pipe at incident energy 500 W/m². Using forced convection with double condenser length increases the cell output power by about 9.1% compared to one heat sink for free convection at falling radiation intensity 3000 W.m^-2. 

Renewable energy applications play a major role in covering the energy demand for building cooling and ventilation. In this paper, an experimental investigation is performed on cooling and ventilation of a building room locating in New Borge Alarb city, Alexandria, Egypt by new combination of solar chimney and geothermal air tube heat exchanger system. PV panel is installed by new technique at the chimney back to produce power
and its performance is compared to an identical PV outside the room. The study is performed for the chimney and PVs facing south of an angle with the horizontal 30° and 45° and for natural and forced airflow inside the geothermal tube. The geothermal tube and chimney ventilation systems are compared with the natural ventilation system of the solar chimney and window. The results indicate that the proposed systems prove their ability to cool the room temperature up to 3.5 °C and change daily its air 42 times. Minimum ventilated air occurs at natural geothermal tube-chimney system of angle 30°. The ratio of the total daily ventilated air by natural geothermal tube-chimney to that by chimney-window is about 56.3% and 65% at 30° and 45°, respectively and for heat released is 55.6% and 64%, respectively. Maximum daily heat released from the room is achieved at chimney inclination angle 45° for natural geothermal tube-chimney-PV system. Maximum PV output power inside the chimney represents 70% of the maximum PV output power outside the chimney which is 120 W/m at chimney inclination angle 30°.

In this study, the performance of single slope solar still combined with enhanced condenser and integrated

with
 parabolic trough solar collector (PTC), is assessed based on productivity, energy, exergy,
exergoeconomic,  and enviroeconomic methodologies. Experiments are conducted using various saline water media  inside a  basin exposed to the hot weather conditions of Sohag city in Upper Egypt. Several solar  still configurations are tested: conventional solar still (CSS), modified solar still (MSS) using aluminum heat sink  as enhanced condenser (HSC), modified solar still incorporated with PTC (MSS + PTC), modified  solar still comprising sand as a porous media inside the basin (MSS + SD), and modified solar
still comprising  sand inside  the basin and incorporated with PTC (MSS + SD + PTC). The experimental findings  revealed that the MSS + SD + PTC achieved the highest freshwater productivity of 4.65 L/m in winter and  9.75 L/m2 in summer, leading to an improvement of around 113 % in winter and 146 % in summer  compared with the CSS system. The highest increase in energy and exergy output per year is obtained
 in the case of MSS + SD + PTC at 139 % and 245 %, respectively. Incorporation of PTC into the MSS  system for all studied water media is found promising in terms of energy payback time, cost, and freshwater yield  compared with MSS without PTC. The exergoeconomic and environmental parameters of  the active systems are found more effective compared with those of the passive systems.

Three-dimensional study of convection-radiation heat transfer of a discrete heat source (chip) inside an enclosure cooled by rectangular finned heat sink is studied. Conduction heat transfer through the enclosure walls and radiation exchange between these walls are considered. Convection heat transfer on the outer surfaces of the enclosure to the ambient is considered. A complete three-dimensional mathematical model of the physical system is presented and solved numerically by using finite difference method and programmed inside MATLAB software and validated by using an experimental work. Results show good agreement between the numerical and experimental results in case of considering radiation. The impact of the enclosure aspect ratio and chip power on
its cooling and heat transfer and fluid flow inside the enclosure is investigated. The results indicate that in an enclosed electronic device, the impact of the radiation is important in the thermal analysis when the natural convection cooling is presented. At chip heat flux of 5 kW/m2 , neglecting radiation impact rises chip temperature by about 20%. The minimum chip temperature is obtained at an aspect ratio of 1.25. Increasing the chip heat flux
and aspect ratio reduces the airflow eddies inside the enclosure. At chip heat flux of 1.25 and 5 kW/m , radiation Nusselt number represents about 17.8 and 19.7% of the total Nusselt number, respectively.  

This paper presents a low power, low noise preamplifier stage with simple common mode desensitization circuit for dynamic comparators. The target application of the proposed circuit is analog to digital converter for biomedical applications. Adopting TSMC 0.18μm technology, the proposed circuit is designed to work in weak inversion using gm/ID design methodology. The simulation results show that the preamplifier stage consumes less than 32nW using power supply of 0.75V. The input referred noise is 17μV, DC gain of 43.15dB and unity gain frequency of 300 kHz

This paper presents an economical study of the effect of demand-side management (DSM) by implementing a PV system on bulk customers on all elements of the electricity sector including their impact on grid operations and planning in the Kingdom of Saudi Arabia. Demand Side Management is assumed to be applied in Riyadh, as a case study, using the concept of load shaving by photovoltaic system implementation for bulk customers as a segment to manage the demand during peak period. The Time of Use (ToU) tariff model is developed and incorporated in this study. Then an economical study is carried out to calculate the money-saving by Saudi Electricity Company as the impact of load shaving at peak period. Moreover, the paper considers the economic impact of the load reduction influences on the long-term forecast and hence the investment in the conventional generation power plants. Finally, the study determines how much is the saving of electricity bills for bulk customers due to PV implantation including the expected payback period to support the usefulness of adopting DSM for the electricity sector in KSA.

This paper presents low voltage low power a rail to rail common mode range clocked comparator. The target application of the proposed circuit is analog to digital converter for biomedical applications. The proposed comparator is composed of two stages which are pre-amplifiers and modified strong-Arm latch. The outputs of NMOS-input and PMOS-input pre-amplifiers are combined by the modified Strong-Arm latch producing rail to rail common mode range clocked comparator. Adopting TSMC 0.18μm technology, the preamplifier stages were designed to work in weak inversion using g m /I D design methodology. The simulation results show that the preamplifier stage consumes less than 0.275μW using power supply of 0.75V. The pre-amplifier DC gain of 43.15dB and unity gain frequency of 300 kHz

Hybrid micro-grid systems (HMGS) are small scale power system where the energy sources are installed to supply local customers. These systems may be considered as promising energy solution to meet the increased in energy demand and traditional sources depletion. Cost of electricity, system reliability, and environmental impacts of the system are three design criteria that must be considered in obtaining the accurate parameters of hybrid renewable energy system components. In this paper, hybrid micro-grid renewable energy system includes photovoltaic system, (PV) wind energy system, (WES) battery bank,(BB) and conventional diesel generator (DG) are proposed to meet the energy requirements in remote area, located in Red Sea called city of Bernice, Egypt, at 23
540 3100 N, 35
280 2100 E. Optimization of Cost of Electricity (COE), Renewable Factor (RF), and Loss of Power Supply Probability (LPSP) are main objective of the designing process of the hybrid system considered as the objective functions. Then, Multi-objective multi-verse optimization (MOMVO) algorithm is used with considering two scenarios, the first one is renewable sources and the second is renewable/diesel energy source. All the possible HMGS configurations namely: PV/battery, wind/battery, PV/wind/battery and PV/battery/diesel, wind/-battery/diesel, PV/wind/battery/diesel are studied and analyzed. Moreover, one year hourly meteorolog-ical weather data for case study are recorded. Reverse osmosis desalination (ROD) is considered in conjunction with the residential load. The proposed power management strategy is used to manage the system operation when supplying the load. A linear fuzzy membership function is used for purpose of decision making. The simulation results show that MOMVO produces appropriate components size and the PV/wind/battery/diesel is the optimum configuration with values of COE = 0.2720$/KWh, LPSP = 0.1397, and RF = 92.37% at w1 = 0.5, w2 = 0.3, and w3 = 0.2. Sensitivity analysis is performed to show the effect of changing system parameters on the objective functions. It is also shown that the techno-economic feasibility of using HMGS for rural electrification systems and enhance energy access.  2021 THE AUTHORS. Published by Elsevier BV on behalf of Faculty of Engineering, Ain Shams Uni-versity. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Agricultural drainage water (ADW) reuse is the most promising option to increase the availability of water for irrigation. The pollution of drainage networks and the Nile River water supply shortage threaten the largest ADW reuse project in Egypt (El-Salam Canal), especially following the construction of the Grand Ethiopian Renaissance Dam (GERD). Accordingly, a one-dimensional hydrodynamic and water quality (WQ) simulation model was built as a tool to manage the quantity and quality of the canal water using MIKE 11 modules. Three proposed scenarios aimed to assess the current situation (Scenario 1), the best WQ parameter reduction ratio of the highly pollutant drains (Scenario 2), and the effect of the construction of the GERD on the canal WQ (Scenario 3). The results provided a quantitative canal WQ management tool to comply with the standards for irrigation purposes and illustrated that after the …