scholarly journals Contribution to the study of combined adsorption–ejection system using solar energy

2017 ◽  
Vol 9 (7) ◽  
pp. 168781401771185
Author(s):  
Amal Bel Haj Jrad ◽  
Mohamed Bechir Ben Hamida ◽  
Rabie Ghnay ◽  
Abdallah Mhimid
Keyword(s):  
Activated Carbon ◽  
Solar Energy ◽  
Simulation Software ◽  
Coefficient Of Performance ◽  
Comsol Multiphysics ◽  
Solar Cooling ◽  
Model And Simulation ◽  
Time Space ◽  
Mass Transfers ◽  
The City

Solar energy is a renewable and free energy. We can take advantage of such characteristics to produce solar cooling through adsorption especially in an area such as the city of Monastir, Tunisia, where the Sun is abundant. A mathematical model and simulation are carried out to optimize heat and mass transfers performance in a flat solar collector using zeolite/water and activated carbon/methanol pairs during desorption phenomena. A commercial simulation software COMSOL Multiphysics has been developed to provide us with the time–space evolution of temperature and average fluid content. Numerical results have shown that the activated carbon desorbs faster than the zeolite. Besides, in order to get an important solar coefficient of performance, it is necessary to have an important incident solar energy. It has also been found that to improve the solar coefficient of performance, an adsorption–ejection system is statically studied.

scholarly journals Design Optimization and Simulation of an Ice Plant Working by Solar Adsorption Technology

2021 ◽  
Vol 1 (4) ◽  
pp. 13-22
Author(s):  
H. A. Alamoudi ◽  
A. M. Abdel-Dayem
Keyword(s):  
Activated Carbon ◽  
Design Optimization ◽  
Winter Season ◽  
Coefficient Of Performance ◽  
Ice Plant ◽  
Adsorption Refrigeration ◽  
Model And Simulation ◽  
Adsorption Technology ◽  
Optimization And Simulation ◽  
Evacuated Tube Collectors

This research presents a design optimization of a solar adsorption ice plant using activated carbon and methanol as working pairs in the climate of Makkah to produce a ton of ice per day. The plant consists of six adsorption refrigeration units. Each unit has 72 separate cylindrical adsorbent beds connected with its own condenser, valve, and evaporator. The unit is heated by seven evacuated-tube collectors connected in parallel. Then the total number of collectors are 42 collectors. The beds are filled by estimated amount of 540 kg of activated carbon with 178 kg of methanol. Selection and dimensioning of each component were carried out based on previous recommended values. A mathematical model and simulation were developed to validate the system performance along the year. The results showed that plant could produce up to ton of ice daily along the year. The coefficient of performance can reach 0.9 with condenser and evaporator temperatures of 35°C and -5°C respectively. The performance of the system is greatly affected by ambient temperature than solar radiation. Therefore, the best performance and largest amount of ice was found in the winter season.

Solar Refrigerating Systems

2013 ◽  
Vol 772 ◽  
pp. 581-586 ◽  
Author(s):  
Ioan Sarbu ◽  
Emilian Valea ◽  
Calin Sebarchievici
Keyword(s):  
Solar Energy ◽  
Cooling System ◽  
Environmental Issues ◽  
Coefficient Of Performance ◽  
Practical Applications ◽  
Solar Cooling ◽  
Important Research Topic ◽  
Absorption Cycle ◽  
Thermal Cooling ◽  
Ejector Cycle

Along with the global warming impacts and climate changes, the demands for air conditioning and refrigeration have increased. Therefore, providing cooling by utilizing renewable energy such as solar energy is a key solution to the energy and environmental issues. In this paper are presented theoretical basis and practical applications for cooling technologies assisted by solar energy and their recent advances. The ejector cycle represents the thermo-mechanical cooling system, and has a higher coefficient of performance (COP) but require a higher heat source temperature than other cycles. Based on the thermal COP of each cycle, the absorption cycle which represents the thermal cooling is preferred to the ejector cycle. Next to improving efficiency of solar cooling technologies, research on advanced solar collector is the most important research topic.

scholarly journals Design and simulation of a 1-GWp solar photovoltaic power station in Sudan

Clean Energy ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 57-78
Author(s):  
Sohaib Nasr Mohamed Abdalla ◽  
Hakan Özcan
Keyword(s):  
Solar Energy ◽  
Net Present Value ◽  
Solar Power ◽  
Northern Region ◽  
Solar Photovoltaic ◽  
Power Station ◽  
Levelized Cost Of Electricity ◽  
Solar Plant ◽  
Performance Rate ◽  
The City

Abstract Developing nations have a critical need to increase electricity supply. Sudan has much unrealized potential for generating solar energy, particularly in the northern region. This research study focuses on designing a 1-GW solar power station in northern Sudan using the PVsyst7.0 software program. To determine the appropriate location for the solar-energy station, 14 criteria were evaluated. This process is generic and suitable for use in any other country. The method for conducting cash-flow estimates and return on investment is illustrated in the economic evaluation. The city of Dongola, the capital of the northern state, was selected because of its high annual irradiance on a horizontal surface at ~2333.2 kWh/m2. The simulation results show that the annual optimum tilt angle of inclination for photovoltaic (PV) modules is 30°, the energy production is 1 979 259 MWh/yr and the average annual performance rate is 0.810. In addition, the electric power consumption per capita in Sudan is 269 kWh/yr, so the proposed solar power plant with 1 979 259 MWh/yr can provide energy to 7.4 million people per year annually and reduce carbon emissions by ~18 million tons of carbon dioxide per year. Economic calculations show that the levelized cost of electricity (LCOE) is $0.06/kWh, the discounted payback period is ~11 years and the net present value is $635 291 000. As a result, the proposed grid-connected PV solar plant is considered economically, technically and environmentally feasible in Sudan.

scholarly journals Effect of magnetic field on nanofluid free convection in Conical Partially Annular Space

2020 ◽  
Vol 330 ◽  
pp. 01005
Author(s):  
Abderrahmane AISSA ◽  
Mohamed Amine MEDEBBER ◽  
Khaled Al-Farhany ◽  
Mohammed SAHNOUN ◽  
Ali Khaleel Kareem ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Hartmann Number ◽  
Volume Fraction ◽  
Boussinesq Approximation ◽  
Simulation Software ◽  
Comsol Multiphysics ◽  
Governing Equations ◽  
Element Analysis ◽  
Vertical Side ◽  
Side Walls

Natural convection of a magneto hydrodynamic nanofluid in a porous cavity in the presence of a magnetic field is investigated. The two vertical side walls are held isothermally at temperatures Th and Tc, while the horizontal walls of the outer cone are adiabatic. The governing equations obtained with the Boussinesq approximation are solved using Comsol Multiphysics finite element analysis and simulation software. Impact of Rayleigh number (Ra), Hartmann number (Ha) and nanofluid volume fraction (ϕ) are depicted. Results indicated that temperature gradient increases considerably with enhance of Ra and ϕ but it reduces with increases of Ha.

The Landscape of War and the Transformations of the Public Sphere

2019 ◽  
Vol 44 (2) ◽  
pp. 62-67
Author(s):  
Dijana Alic
Keyword(s):  
The European Union ◽  
Independent State ◽  
The Public ◽  
Time Space ◽  
History Of ◽  
The Public Sphere ◽  
Modern Warfare ◽  
The Impact ◽  
The City ◽  
Edward Soja

On 6 april 1992, the european union (eu) recognised bosnia and hercegovina as a new independent state, no longer a part of the socialist federal republic of Yugoslavia. The event marked the start of the siege of sarajevo, which lasted nearly four years, until late february 1996. It became the longest siege in the history of modern warfare, outlasting the leningrad enclosure by a year. During its 1425 days, more than 11,500 people were killed. The attacks left a trail of destruction across the city, which began to transform it in ways not experienced before. This paper explores how the physical transformation of sarajevo affected the ways in which meaning and significance were assigned to its built fabric. I argue that the changes imposed by war and the daily destruction of the city challenged long-established relationships between the built fabric and those who inhabited the city, introducing new modes of thinking and interpreting the city. Loosely placing the discussion within the framework of ‘Thirdspace', established by urban theorist and cultural geographer edward soja, i discuss the relationship that emerged between the historicality, sociality and spatiality of war-torn sarajevo. Whether responding to the impacts of physical destruction or dramatic social change, the nexus of time, space and being shows that the concept of spatiality is essential to comprehending the world and to adjusting to and resisting the impact of extraordinary circumstances. Recognising the continuation of daily life as essential to survival sheds light on processes of renewal and change in a war-affected landscape. These shattered urban spaces also show the ways in which people make a sense of place in relation to specific socio-historical environments and political contexts.

scholarly journals Time-Space Characterization of Wellbore-Cement Alteration by CO2-Rich Brine

Geosciences ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 490
Author(s):  
Maria Garcia-Rios ◽  
Philippe Gouze
Keyword(s):  
Numerical Models ◽  
Reaction Rates ◽  
Diffusion Reaction ◽  
Cement Matrix ◽  
Relative Distribution ◽  
Reaction Fronts ◽  
Time Space ◽  
Mass Transfers ◽  
Dissolution And Precipitation ◽  
Diffusion Properties

The risk of CO2 leakage from damaged wellbore is identified as a critical issue for the feasibility and environmental acceptance of CO2 underground storage. For instance, Portland cement can be altered if flow of CO2-rich water occurs in hydraulic discontinuities such as cement-tubing or cement-caprock interfaces. In this case, the raw cement matrix is altered by diffusion of the solutes. This fact leads to the formation of distinctive alteration fronts indicating the dissolution of portlandite, the formation of a carbonate-rich layer and the decalcification of the calcium silicate hydrate, controlled by the interplay between the reaction kinetics, the diffusion-controlled renewing of the reactants and products, and the changes in the diffusion properties caused by the changes in porosity induced by the dissolution and precipitation mechanisms. In principle, these mass transfers can be easily simulated using diffusion-reaction numerical models. However, the large uncertainties of the parameters characterizing the reaction rates (mainly the kinetic and thermodynamic coefficients and the evolving reactive surface area) and of the porosity-dependent diffusion properties prevent making reliable predictions required for risk assessment. In this paper, we present the results of a set of experiments consisting in the alteration of a holed disk of class-G cement in contact with a CO2-rich brine at reservoir conditions (P = 12 MPa and T = 60 °C) for various durations. This new experimental protocol allows producing time-resolved data for both the spatially distributed mass transfers inside the cement body and the total mass transfers inferred from the boundary conditions mass balance. The experimental results are used to study the effect of the fluid salinity and the pCO2 on the overall reaction efficiency. Experiments at high salinity triggers more portlandite dissolution, thinner carbonate layers, and larger alteration areas than those at low salinity. These features are accompanied with different spatial distribution of the alteration layers resulting from a complex interplay between salinity-controlled dissolution and precipitation mechanisms. Conversely, the effect of the pCO2 is more intuitive: Increasing pCO2 results in increasing the overall alteration rate without modifying the relative distribution of the reaction fronts.

A Method for Harvesting Energy Using Piezoelectric Transducers

2015 ◽  
Vol 727-728 ◽  
pp. 607-611 ◽  
Author(s):  
Kshitij Chopra ◽  
Kritika Nigam ◽  
Sujata Pandey
Keyword(s):  
Zinc Oxide ◽  
Simulation Software ◽  
Piezoelectric Transducers ◽  
Comsol Multiphysics ◽  
Ambient Vibrations ◽  
Multiphysics Simulation

This paper analyses the behaviour ofpiezoelectric transducer for harvesting energy. The transducer was designedusing different materials for harnessing energy that include Zinc Oxide, LeadZirconate Titanate (PZT-2) and Quartz. The transducer was simulated using thesematerials and the voltage generated from ambient vibrations was analysed. MEMsmodule of COMSOL Multiphysics Simulation software was used to perform thesimulations. Behaviour of different materials towards various frequencies madeknown in this study gives an opportunity to estimate the fabricated device and alsosheds light on prospective applications it fits.

Transient Analysis and Performance Prediction of a Solid Adsorption Solar Refrigerator

Solar Energy ◽  
2005 ◽  
Author(s):  
Emmanuel E. Anyanwu ◽  
Nnamdi V. Ogueke
Keyword(s):  
Performance Prediction ◽  
Transient Analysis ◽  
Adsorption Process ◽  
Design Tool ◽  
Coefficient Of Performance ◽  
Collector Plate ◽  
Tube Arrangement ◽  
And Performance ◽  
Mass Transfers ◽  
The Mathematical Model

The transient analysis and performance prediction of a solid adsorption solar refrigerator, using activated carbon/methanol adsorbent/adsorbate pair are presented. The mathematical model is based on the thermodynamics of the adsorption process, heat transfer in the collector plate/tube arrangement, and heat and mass transfers within the adsorbent/adsorbate pair. Its numerical model developed from finite element transformation of the resulting equations computes the collector plate and tube temperatures to within 5°C. The condensate yield and coefficient of performance, COP were predicted to within 5% and 9%, respectively. The resulting evaporator water temperature was also predicted to within 4%. Thus the model is considered a useful design tool for the refrigerator to avoid costly experimentation.

Experience With a Solar Heating ATES System for a University Building

1994 ◽  
Vol 116 (2) ◽  
pp. 88-93 ◽  
Author(s):  
E. Hahne ◽  
M. Hornberger
Keyword(s):  
Solar Energy ◽  
Heat Pump ◽  
Waste Heat ◽  
Heating System ◽  
Solar Heating ◽  
Coefficient Of Performance ◽  
Solar Collectors ◽  
Power Station ◽  
Heat Demand ◽  
Heat Store

At Stuttgart University, a solar heating system for an office building with laboratories and lecture rooms was installed in 1985. It consists of 211 m2 of unglazed solar collectors, a 1050 m3 water-flooded pebble bed heat store, and a heat pump. Heat can be supplied to the store from the solar collectors or from a power station (as waste heat). The whole system has worked successfully for five years under varied strategies. In the first two heating periods, the heating strategy was aimed to collect as much solar energy as possible. Thus, about 60 percent of the heat demand could be covered by solar energy; but the yearly heat pump coefficient of performance (COP) was only around 2.76. With an improved heat pump, a monthly COP of 3.6 was obtained. Heat losses from the storage amounted to about 20 percent.

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