Ahmed Hamed

• Prof
• Professor (Full) at MansouraUniversity

Water shortages have become a major global crisis and can be a significant challenge for many countries. Fog collection technology is a sustainable and cheap remedy that contributes to reducing the effect of water shortages. Herein, a hydrophobic fog collector is presented that improves the fog collection rate by using a combination of acrylic pain...

The most valuable resource for sustaining life on earth is water. In dry and semi-arid areas, the problem of water scarcity can be resolved with the aid of fog collection techniques employing fog collectors. Fog collection is greatly influenced by a variety of factors. Some are design parameters, while others depend on ambient circumstances. Geomet...

Solar desalination systems are a promising solution to the water scarcity problem since the majority of the earth’s water resources are salty. With the increasing focus on desalination research, many innovative methods are being developed to extract salts from saline water. Energy consumption is a significant concern in desalination, and renewable...

Enhancing the performance of a concentrator photovoltaic (CPV) system by integrating a solar tracker to concentrate the solar irradiance on the target area is important. Thus, a dual‐axis elliptic solar tracker is designed, fabricated, and experimentally evaluated. The altitude and solar azimuth angles of the tracker are adjusted based on governing...

Thermal energy storage (TES) systems are used to overcome daytime solar energy instability and fluctuation. Thermochemical TES systems are more promising than sensible and latent TES systems, particularly for solar energy applications with low and medium temperatures. The most recent literature reviews summarized the advancement of sorption energy...

Conducting an outdoor experimental investigation of a hybrid concentrator photovoltaics (CPV)/thermoelectric generators (TEG) system's performance is of great importance. It provides a reliable performance characteristic, as it is carried out under real solar spectral and atmospheric conditions. In the current work, a multi-junction solar cell subj...

Desiccant dehumidification systems are thermally regenerated systems that can be used either as standalone or as complementary additives for conventional cooling systems. One of their best competitive qualities is the potential to utilize low-grade heat sources for the regeneration process, thus decreasing electrical power consumption and scaling b...

This study presents an experimental and theoretical investigation of a fog desalination system powered by an evacuated tube solar water heater (ETSWH). This system is composed of a high-pressure fog pump, two fog nozzles each of diameter 0.1 mm, condenser, finned tube heat exchanger, evaporation and condensation duct, and a natural flow ETSWH of te...

In the present work, new hybrid cooling system is demonstrated and compared with other configurations of gas turbine inlet air-cooling systems. The cooling configurations include the earth-air heat exchanger, fogging and a new hybrid cooling system. Three models are developed, the first is for prediction of the cooling potential of the fogging syst...

In the present work, new hybrid cooling system is demonstrated and compared with other configurations of gas turbine inlet air-cooling systems. The cooling configurations include the earth-air heat exchanger, fogging and a new hybrid cooling system. Three models are developed, the first is for prediction of the cooling potential of the fogging syst...

Theoretical and experimental investigation of the thermal energy storage of an open adsorption system is presented. The theoretical model describes the mass and energy transfers in the system. The coupled energy and mass balance equations have been solved using the COMSOL™ software. The model was validated against laboratory experiments performed a...

The application of earth to air heat exchanger (EAHE) as an inlet air cooling system on gas turbine performance has been investigated. Transient, one-dimensional model was developed for predicting the thermal performance of EAHE. Gas turbine output power, efficiency and specific fuel consumption are assessed with application of EAHE. MATLAB program...

According to the high potential of solar energy in Saudi Arabia, the possibility of converting a large amount of such energy into hydrogen via electrolysis of water is considered as necessary, viable and challenging. The present paper introduces an experimental investigation of a small solar hydrogen production unit (SHPU) according to the atmosphe...

Unsteady-state (batch) adsorption is very widely used in recovery of valuable solvent vapors from gases as well as dehumidification of air for air-conditioning and industrial applications. In such systems, the desiccant is subjected to cyclic operation of adsorption and subsequent desorption. The design of a solid bed adsorber and prediction of the...

This paper gives a detailed account of the general features of the major desiccant regeneration techniques and configurations of the related systems; meanwhile, attention has been paid to both technological development of solar powered regenerator, which is a key component of the liquid-desiccant dehumidification system. Studies to improve the syst...

In the present work, experimental investigation on the dynamic performance of sealed and less maintenance vertical packed porous bed desiccant dehumidification system has been carried out. The desiccant bed operates as an adsorber and then operates as a regenerator intermittently. In the experimental part of this investigation, silica gel is applie...

In this work, a simple solar kiln has been investigated for drying the waste of palm trees. This kiln is manufactured from wood available in the local market. It has a vertical front facade and a roof inclined at an angle of 25 degrees on the horizontal which, made of solid transparent plastic with a thickness of 4 mm. The humid hot air at the top...

In the present study, dynamic performance of single bed desiccant regeneration system has been investigated experimentally. The desiccant bed operates as an adsorber and then as a regenerator, intermittently. In the experimental work of this investigation, Silica gel is used as a desiccant material. In the regeneration process, hot air from an air...

In the present work, a novel configuration of solar-powered desiccant dehumidification system is demonstrated. A rotating wick made of double layered cotton-cloth has been applied as a desiccant solar regenerator. The blackened wick-surface, which is impregnated with calcium chloride solution, moves between two rotating pulleys at an inclination an...

In the present work, a rotating tilted wick, which is made of a double layer cotton-cloth, has been used as a desiccant regenerator. Calcium chloride solution is applied as the working desiccant. The wick surface, which is impregnated with the desiccant solution, moves between two rotating pulleys at an inclination angle of 20 degrees. The regenera...

This paper presents the modeling and simulation of solar-powered desiccant regenerator used for open absorption cooling cycles. The input heat, which is the total radiation incident on an inclined surface, is evaluated via a solar radiation model in terms of the location, day of the year, and time of the day. Calcium Chloride (CaCl2) is applied as...

In the present work, an experimental investigation on the performance of radial flow desiccant bed using activated alumina has been carried out. 39.860 kg of spherical particles of activated alumina with an average diameter of 4 mm was used to form a hollow cylindrical bed with length of 90 cm and outer and inner diameters of 27.8 and 10.8 cm, resp...

This paper presents the modeling and simulation of solar-powered desiccant regenerator used for open absorption cooling system. The input heat, which is used to re-concentrate the desiccant solution, is estimated via a real-time solar radiation model in terms of the location, day of the year and time of the day. Lithium chloride (LiCl) and calcium...

Theoretical and experimental investigation on the application of flat plate solar water heater coupled with air humidifier for regeneration of liquid desiccant has been presented in this work. The heated water from the storage tank of the solar heating system is circulated in a finned tube air heater. Hot air from the air heater is blown through a...

In the present work, an experimental investigation on the performance of radial flow desiccant bed using activated alumina has been carried out. 39.860 kg of spherical particles of activated alumina with an average diameter of 4 mm was used to form a hollow cylindrical bed with length of 90 cm and outer and inner diameters of 27.8 and 10.8 cm, resp...

In the present work, an investigation on the application of solar energy to heat a sandy bed impregnated with calcium chloride for recovery of water from atmospheric air is presented. The study also aimed at evaluating the effects of different parameters on the productivity of the system during regeneration. These parameters include system design c...

This paper presents the modeling and simulation of solar-powered desiccant regenerator used for open absorption cooling system. The input heat, which is used to re-concentrate the desiccant solution, is estimated via a real-time solar radiation model in terms of the location, day of the year and time of the day. Lithium chloride (LiCl) and calcium...

Fresh water is the essence of human life. It is the most important constituents of environment and a basic human requirement for domestic, industrial and agriculture purposes. Production of fresh water using desalination technologies driven by solar energy is thought to be a viable solution to the water scarcity at remote, arid and semi-arid areas,...

In the present work, an investigation on the application of solar energy to heat a sandy bed impregnated with calcium chloride for recovery of water from atmospheric air is presented. The study also aimed at evaluating the effects of dif-ferent parameters on the productivity of the system during regeneration. These parameters include system design...

Fresh water supply is one of the most limiting conditions for the populations of arid regions. The present paper covers the working principles of systems and processes for extracting water from atmospheric air. Moreover, a summary of the experimental and analytical studies which investigate system performance has been made. Some new designs that gr...

The enhancement of the productivity of the solar desalination system, in a certain location, could be attained by a proper modification in the system design. Therefore, different design configurations could be found in literatures. However, the increase in the system productivity with high system cost may increase also the average annual cost of th...

Transient adsorption/desorption characteristics of spherical particles of silica gel (about 3mm in diameter) in a fluidized bed have been studied experimentally. To control the humidity of inlet air, a humidifier is designed and fitted in a proper location in the system. The system is well instrumented to measure the inlet and outlet air parameters...

In the present work, theoretical and experimental investigation on the design and operation of a solar concentrating-tracking system is carried out. In the theoretical study two different designs are proposed and analyzed. Both designs generate a concentrated beam of solar radiation. The beam direction can be fixed and controlled, so that it can...

Theoretical investigation on the performance of lithium chloride (LiCl) absorption cooling system using an artificial neural network (ANN) model is presented. Tabulated data from the literature are used to construct the ANN model. Solar collector desiccant/regenerator is applied to re-concentrate the working solution. Using the proposed model, the...

A multiple-layer artificial neural network (ANN) model has been applied to study the performance of a solar liquid-desiccant dehumidification/regeneration system. The experimental results of a previous study are used to construct and test the ANN model. Then the model has been utilized to describe the effect of the inlet conditions of the air and c...

In the present work a theoretical investigation of the cyclic operation of the radial flow solid desiccant dehumidifier has been reported. A mathematical model has been developed to predict the effect of air inlet conditions (humidity, temperature and flow rate) as well as bed design parameters on the desiccant bed dynamic performance during cyclic...

In the present work a theoretical investigation of the cyclic operation of the radial flow solid desiccant dehumidifier has been reported. A mathematical model has been developed to predict the effect of air inlet conditions (humidity, temperature and flow rate) as well as bed design parameters on the desiccant bed dynamic performance during cyclic...

An experimental study on the performance characteristics of proton-exchange-membrane fuel cell (PEMFC) has been carried out. The study has been performed on a single PEMFC unit with an active area of 25 cm2 using two different cell configurations. The test system has been established to control each of the temperature and the relative humidity of t...

In the present work, a theoretical and experimental investigation of the radial flow solid desiccant dehumidifier has been reported. In the experimental study, spherical particles of silica gel (indicating type) of 3mm average diameter were used as the working desiccant in the dehumidifier. The bed under investigation was of radial flow and cylindr...

This paper presents an experimental investigation on the adsorption and desorption operations in an inclined-fluidized bed using silica gel as the working desiccant. The experimental system involves a circular glass tube containing the particles of silica gel, which is tested at an inclination angle of 45°. The moisture capacity of the bed is measu...

In the present work, theoretical and experimental evaluation of the effect of bed configuration and operating conditions on the performance of desiccant dehumidification system has been carried out. A new rotating absorption disk has been designed and constructed to be tested in the experimental work. The desiccant wheel has a cylindrical shape of...

Transient adsorption/desorption characteristics of solid desiccant particles in fluidized bed have been presented. The system operates in batch mode and the atmospheric air with controlled inlet humidity and temperature is dehumidified by the applied desiccant. Also, heated air is used for regeneration purposes. A simplified analytical solution, wi...

In the present work, theoretical and experimental evaluation of the effect of bed configuration and operating conditions on the performance of desiccant dehumidification system has been carried out. A new rotating absorption disk has been designed and constructed to be tested in the experimental work. The desiccant wheel has a cylindrical shape of...

Theoretical and experimental investigation on the desorption characteristics of a packed porous bed is presented in this study. The granules of burned clay are applied as a desiccant carrier. Calcium chloride is used as the working desiccant. The theoretical model defines the transient gradient of air stream parameters (humidity and temperature) as...

This paper presents an investigation on the natural absorption of water vapour of the gaseous-air mixture on the horizontal surface of a sandy layer impregnated with calcium chloride as the working desiccant. Seven layers with different values of desiccant to sand mass ratio in the range from 0.1 to 0.4 are studied. Isothermal absorption is assumed...

This paper presents a theoretical and experimental study of the transient adsorption characteristics of vertical packed porous bed. The theoretical model describes the effect of independent parameters (time and vertical distance through the bed) on the vertical gradient of adsorbable fluid in the bed. A simplified analytical solution, for specific...

This paper presents an investigation on the absorption/regeneration mass transfer through parallel plates of cloth layers. Cloth layers impregnated with calcium chloride solution are subjected to absorption of water vapour from a flowing air stream with subsequent regeneration by a hot stream. Concentration range of desiccant from 0.2 to 0.5 is app...

An investigation on the operation of packed tower for the regeneration of liquid desiccant is presented. A theoretical model demonstrating the effect of the system parameters is described. The experimental results are plotted to illustrate the effect of air and liquid parameters on the output variables. The regeneration process is shown to be highl...

An integrated desiccant/solar collector system for production of fresh water from atmospheric air is described. The solar driven system provided about 1.5 l of fresh water per square meter per day. The system involves the absorption of water vapor from ambient air during the night and simultaneous desiccant regeneration and water vapor condensation...

Description and analysis of the theoretical cycle for absorption of water vapour from air with subsequent regeneration, by heating is presented. Properties of the desiccant (CaCl2) applied in the study are correlated in a simplified form, which can be used in computational analysis of the cycle performance. To predict the effect of ambient conditio...