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Wyszukujesz frazę "Ammar, N." wg kryterium: Autor


Wyświetlanie 1-3 z 3
Tytuł:
The effect of limestone fineness on ternary cement fresh-state and early-age properties
Autorzy:
Ammar, N.
Zeghichi, L.
Powiązania:
https://bibliotekanauki.pl/articles/89048.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Wydział Geoinżynierii, Górnictwa i Geologii. Instytut Górnictwa
Tematy:
addition
limestone
pozzolan
fineness
shrinkage
setting time
mechanical performance
Opis:
During cement production, a significant amount of CO2 is released into the atmosphere, it is estimated that the production of each ton of clinker free about a ton of second carbon oxide. The use of additions as constituents of cement reduces the amount of clinker, where CO2 emissions are reduced. The combination of two or three additions with Portland cement can develop new types of binders (ternary or quaternary cement) with improved physical and mechanical properties compared to Portland cement alone. The objective of this work involves the study of the effects of the fineness of limestone on the physical and mechanical properties of ternary cements containing pozzolan and limestone with specific area of 3500, 5500 and 11000 cm2/g, respectively. The amount of clinker is fixed at 65% , that of limestone is varied from 10 to 35% by weight of cement, the remain is constituted of pozzolanic addition. The results showed that increasing the surface area of limestone could be with a favorable effect on the physical properties in particular the setting time and the shrinkage; further to good strength, mainly at early ages. The higher dosages of pozzolan reaching 25 % gave better mechanical performances among all other mixtures. It can be concluded that the use of combined mineral additions, limestone and pozzolan could be beneficial to formulate ternary cements with improved physical and mechanical properties for mortars based on such binders.
Źródło:
Mining Science; 2017, 24; 195-208
2300-9586
2353-5423
Pojawia się w:
Mining Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
CFD modeling of syngas combustion and emissions for marine gas turbine applications
Autorzy:
Ammar, N. R.
Farag, A. I.
Powiązania:
https://bibliotekanauki.pl/articles/259882.pdf
Data publikacji:
2016
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
CFD
syngas fuel
combustion characteristics
exhaust gas emissions
Opis:
Strong restrictions on emissions from marine power plants will probably be adopted in the near future. One of the measures which can be considered to reduce exhaust gases emissions is the use of alternative fuels. Synthesis gases are considered competitive renewable gaseous fuels which can be used in marine gas turbines for both propulsion and electric power generation on ships. The paper analyses combustion and emission characteristics of syngas fuel in marine gas turbines. Syngas fuel is burned in a gas turbine can combustor. The gas turbine can combustor with swirl is designed to burn the fuel efficiently and reduce the emissions. The analysis is performed numerically using the computational fluid dynamics code ANSYS FLUENT. Different operating conditions are considered within the numerical runs. The obtained numerical results are compared with experimental data and satisfactory agreement is obtained. The effect of syngas fuel composition and the swirl number values on temperature contours, and exhaust gas species concentrations are presented in this paper. The results show an increase of peak flame temperature for the syngas compared to natural gas fuel combustion at the same operating conditions while the NO emission becomes lower. In addition, lower CO2 emissions and increased CO emissions at the combustor exit are obtained for the syngas, compared to the natural gas fuel.
Źródło:
Polish Maritime Research; 2016, 3; 39-49
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermo-economic analysis and environmental aspects of absorption refrigeration unit operation onboard marine vehicles: RO- PAX vessel case study
Autorzy:
Ammar, N. R.
Sediek, I. S.
Powiązania:
https://bibliotekanauki.pl/articles/260242.pdf
Data publikacji:
2018
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
ship emissions
IMO
lithium bromide-water ARU
thermodynamic analysis
economic and environmental analysis
Opis:
Marine diesel engines lose a huge amount of fuel heat content in the form of exhaust gas and jacket cooling water, especially onboard high-powered marine vehicles such as Ro-Pax ships. In this paper, the possibility of using the waste heat of marine diesel engines as a source of heat for air conditioning absorption system is investigated. The thermodynamic analysis, in addition to the environmental and economic analysis of the air condition absorption cycle operated with two heat sources using lithium bromide as absorbent, are performed using the Engineering Equation Solver (EES) software. The last 10 years have seen a steady growth in the passenger ferry and Ro-Pax market, with particularly strong growth in passenger numbers. As a case study, a Ro-Pax vessel operating in the Red Sea area is considered, regarding the profitability of using air conditioning absorption system. The results show specific economic benefits of the jacket cooling water operated absorption refrigeration unit (ARU) over the exhaust gas operated unit, with annual costs of capital money recovery of 51,870 $/year and 54,836 $/year, respectively. Environmentally, applying an ARU machine during cruising will reduce fuel consumption by 104 ton/year. This, in turn, will result in reducing NOx, SOx, and CO2 emissions with cost-effectiveness of 7.73 $/kg, 20.39 $/kg, and 0.13 $/kg, respectively.
Źródło:
Polish Maritime Research; 2018, 3; 94-103
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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