Mohamed L. Elsayed

• Doctor of Philosophy
• Professor (Assistant) at Zagazig University

Steam ejectors are a promising energy-saving technology. Therefore, enhancing their relatively low entrainment performance is essential for expanding their industrial applications. In the present study, a novel ejector design, in which an annular cavity bypass is used in the primary nozzle, has been proposed to improve the entrainment performance o...

The current study presents a numerical investigation of a staggered semi-circular tube bank in crossflow of air to determine its thermal and hydraulic characteristics. The effects of incorporating longitudinal fins are also investigated using different fin lengths. The study covers a range of Reynolds number from 1,000 to 10,000. Correlations for t...

In the present work, the thermal/hydraulic characteristics of a semi-circular cylinder in crossflow of air have been numerically investigated at Reynolds number range between 10³ and 10⁴. Various attack angles between −90 and 90° were considered. The effect of finning was investigated at zero attack angle using three fin configurations (front fin,...

Global energy consumption is continuously increasing in the world due to population growth and improving living standards. Also, fresh water demand is projected to increase by around 55% by 2050. Therefore, designing and developing a system utilizing a combined power cycle to produce fresh water is an attractive solution to address these needs. Thi...

n this work, a multigeneration system is proposed for power, cooling and freshwater production. The waste heat from a SIEMENS SGT6-2000E GT is utilized to drive a supercritical CO2 recompression Brayton cycle (SCRBC) and multi-effect desalination (MED) with thermal vapor compressor (TVC), while the waste heat from the pre- cooler of the SCRBC is ut...

Boiling point elevation (BPE) for high salinity solutions is a crucial parameter that significantly affects the overall thermal efficiency of desalination, water treatment, and many other industrial processing systems, especially when minimum or zero liquid discharge is a key requirement. This paper addresses the discrepancies among the empirical c...

Photothermal water evaporation using natural solar energy has been attracted more attentions due to wide applications such as water purification, sterilization, power generation and energy conservation. This article reports a low-cost and stable material for efficient generation of water vapor as well as saline and pollution water treatment. The hi...

The smooth circular tubes are typically used in air-cooled heat exchangers systems. In literature, various research toward improving the hydraulic/thermal performance by changing the tubes' inner surface topology is found. In the current work, fluid friction and heat transfer characteristics of air-cooled tube heat exchangers with installed ribs an...

There is an increasing trend for incorporating Electro-Mechanical Actuators (EMAs) in aerospace applications to reduce weight and cost. Due to the high-power density required for EMAs in aircraft applications, they are prone to overheating. Pushing the wing-bay air on a finned EMA surface using axial flow fans is the most practical way to cool the...

In the present study, the thermal performance of an enhanced air-cooled heat sink system, comprising of a parallel plate-fin heat sink (PPFHS) with a guide plate installed to alter the bypass flow, was analyzed for fan-driven convection conditions at various altitudes from sea level to 12,000 m. Numerical simulations were carried out using ANSYS Fl...

A cogeneration system is proposed for power and fresh water production in which the waste heat from a supercritical CO2 recompression Brayton cycle is utilized to power a conventional multi-effect desalination system. Energy, exergy and exergoeconomic analyses are performed for the proposed system and compared to a stand-alone supercritical CO2 rec...

Performance of two types of desiccant silica gel aluminum foam heat exchangers - desiccant coated heat exchanger (DCHE) and desiccant packed heat exchanger (DPHE) are evaluated experimentally and numerically. The DCHE is fabricated by coating silica gel over the ligaments of an aluminum foam, while the DPHE is built by packing an aluminum foam with...

The potential of using a full shield or partial shield with a guide plate to control the bypass cooling air flowing above a heat sink is numerically modeled using two different scenarios of inlet conditions – fixed mass flow rate and specified fan curve. Excellent agreement is observed when the simulation results are compared with available experim...

Effective thermal conductivity of a silica-gel/water adsorption packed bed is significantly enhanced by placing silica-gel particles in a high-porosity aluminum foam. The enhancement leads to several folds increase in the specific cooling power (SCP), cooling capacity per unit volume (CPv) and coefficient of performance (COP) of an adsorption cooli...

An exergo-economic model is used to simulate four different feed configurations of multi-effect desalination with thermal vapor compressor (MED-TVC) system. The feed configurations considered are backward feed (BF), forward feed (FF), parallel feed (PF) and parallel cross feed (PCF). The model results indicate that the PCF configuration has better...

A lab-scale adsorption unit is designed and constructed to investigate its efficacy under typical operating conditions of a practical adsorption cooling system. A detailed coupled heat and mass transfer (CHMT) model and a lumped parameter (LP) model are implemented to estimate the Specific Cooling Power (SCP) of an adsorption cooling system using s...

A thermo-economic analysis is carried for the current integrated supercritical carbon dioxide (sCO2) Brayton cycle with both multi-effect desalination coupled with mechanical vapor compression (MED-MVC) and conventional MED system. The conventional MED system uses hot water as the heat source by recuperating the waste heat from the sCO2 cycle. The...

In this article, a scaling analysis of heat and mass transfer processes in an adsorption packed bed is presented. New scaling parameters that characterize the performance of the adsorption cooling bed are derived and their importance are discussed. In addition, a numerical study is performed to illustrate the roles played by the newly derived scali...

The current study describes a detailed steady-state analysis and transient operation of a multi-effect desalination plant with a thermal vapor compressor unit (MED-TVC). The model developed is based on solving the basic conservation equations of mass, energy, and salt. It can predict steady-state operation and transient behavior when the plant is s...

In this study, exergy analysis of four different feed configurations of a multi-effect desalination with mechanical vapor compressor (MED-MVC) system is initially studied to identify the area of exergy destruction within system components and followed by an exergo-economic study. The feed configurations considered are forward feed (FF), backward fe...

An exergo-economic model is used to assess the performance of a multi-effect desalination plant integrated to a mechanical vapor compressor unit (MED-MVC) with a water production capacity of 1500 m³/day. The results show that the second law efficiency (ηII) is 2.8%. The MVC and evaporator units are responsible for about 39 and 52% of the total exer...

Four different configurations of Multi-Effect-Desalination (MED): backward feed (BF), forward feed (FF), parallel feed (PF) and parallel/cross feed (PCF) are modeled in steady and dynamic operation to examine the behavior of these configurations under transient operation. Adding thermal vapor compressor (TVC) unit with the last effect of parallel/c...

The choice of a suitable adsorbate/adsorbent pair is critical for an adsorption cooling cycle. The surface characteristics and thermo-physical properties of the adsorbent, and the adsorption rate of adsorbate are key parameters in making the choice. Through literature review, it is found that there are disagreements among the experimental measureme...

A newly designed packed bed for use in adsorption cooling (AC) systems is evaluated in this research. The bed is modular and can be scaled for a given cooling load. An experimental setup is built to measure the adsorption kinetics of one module under typical operating conditions. Also, a transient three-dimensional local thermal non-equilibrium mod...

Multi-Effect-Desalination (MED) may be exposed to fluctuations (disturbances) in input parameters during operation. Therefore, there is a requirement to analyze the transient behavior of such MED systems. In this work, a dynamic model is developed and used to examine the effect of abrupt and ramp changes in the main operational parameters on the pl...

This paper addresses the discrepancies among the common adsorption isotherms of silica-gel/water provided in the literature. It is reported that the Freundlich model and Tòth equation cannot be used to estimate the uptake at relative pressure less than 0.15. In addition, inconsistencies are found among the various models and equations used to descr...

A new bed configuration consists of two layers of packed beads separated by vapor passage is simulated using transient three-dimensional local thermal non-equilibrium model (LTNE). Darcy–Brinkman equation is solved in both the porous layers and the vapor passage. Silica-gel/water is selected as a working pair. Heat and mass diffusion time are calcu...

Heat transfer and pressure drop characteristics of a set of pin-fins with uniform heat flux were investigated experimentally and numerically. Test set-up was designed to assess the effects of mass flow rate, fin height, and fin density on convection heat transfer and pressure drop. In the numerical investigation, the flow field of various design pa...

The attachment of a shield to a heat sink enhances the thermal performance. But, forming slots in the shield increases thermal resistance. We found that increasing the slot width enhances the flow performance over the heat sink and this improvement continues as the number of slots increases, but the thermal performance, on the other hand, decreases...

This research aims at studying the effect of using a heat shield on the performance of a parallel plate -finned- heat sink. Both numerical and experimental approaches were performed. In the numerical part, the flow field and various design parameters of the heat sink were simulated. The simulation is considered three dimensional, viscous, steady, a...