7 results on '"Imran Nazir Unar"'
Search Results
2. Kinetic modeling of gasification reactions of CO2 and H2O for Thar lignite char at elevated pressures
- Author
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Rasool Bux Mahar, M. Aslam Uqaili, Ghulamullah Maitlo, Imran Nazir Unar, and Abdul Ghani Pathan
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Materials science ,General Chemical Engineering ,Analytical chemistry ,chemistry.chemical_element ,02 engineering and technology ,Activation energy ,010402 general chemistry ,Kinetic energy ,01 natural sciences ,Biochemistry ,Industrial and Manufacturing Engineering ,symbols.namesake ,Materials Chemistry ,Coal ,Char ,Quartz ,Arrhenius equation ,Atmospheric pressure ,business.industry ,General Chemistry ,021001 nanoscience & nanotechnology ,Nitrogen ,0104 chemical sciences ,chemistry ,symbols ,0210 nano-technology ,business - Abstract
Gasification reactions of Thar coal chars with CO2 and H2O have been investigated, using pressurized thermo-gravimetric analyzer (PTGA). A quartz fixed-bed reactor was used to prepare coal char at 900 °C with a nitrogen environment. Dynamic heating segments were maintained with a constant heating rate during all experiments. The temperature was raised from room temperature to 1000 °C, at different pressures 1 atm., 5 atm., and 10 atm. using pure reacting gases (CO2 and H2O). The weight loss data obtained from PTGA results were used to study the kinetic behavior of Thar lignite char for gasification reactions with CO2 and H2O as gasifying reacting species. It was observed that gasification reactions of char with reacting gas CO2 and char with reacting gas steam (H2O) initiated at 750 °C and completed after reaching 950 °C, at atmospheric pressure, but the occurrence of reactions was slightly delayed at high pressures. Volumetric Model and Grain Model were used to develop a kinetic model for Thar lignite. The direct plot and integral methods were used to calculate Arrhenius parameters such as the pre-exponential factor (A) and activation energy (E). An increase of A and E was also observed in increasing pressures. The activation energy (E) was investigated from 244.64 to 317.6 kJ/mol at atmospheric pressure; whereas, it is lying in the range of 286.13–356.67 kJ/mol at a pressure of 10 atm.
- Published
- 2020
3. Experimental study and dynamic simulation of melanoidin adsorption from distillery effluent
- Author
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Shoaib Ahmed, Abdul Qayoom Memon, Rasool Bux Mahar, Hassnain Abas Khan, Abdul Sattar Jatoi, Imran Nazir Unar, Abdul Karim Shah, and Ghulamullah Maitlo
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Langmuir ,Polymers ,Health, Toxicology and Mutagenesis ,010501 environmental sciences ,Coal Ash ,01 natural sciences ,symbols.namesake ,Adsorption ,Environmental Chemistry ,Freundlich equation ,Effluent ,0105 earth and related environmental sciences ,Chemistry ,Melanoidin ,Langmuir adsorption model ,General Medicine ,Hydrogen-Ion Concentration ,Pollution ,Dilution ,Kinetics ,Coal ,Chemical engineering ,Fly ash ,symbols ,Water Pollutants, Chemical - Abstract
This work aims to utilize fly ash from a thermal power station for melanoidin reduction from distillery effluent by adsorption. To accomplish this, coal fly ash was modified through chemical treatment and was then tested for melanoidin adsorption as a function of various melanoidin concentrations, contact time, and pH. The specific novelty of this study is the evaluation of coal fly ash as a low-cost adsorbent for melanoidin removal. Furthermore, the simulation study was carried out using Aspen ADSIM software in order to optimize the commercial usage of the prepared adsorbent. The main results achieved include the maximum removal efficiency of 84% which was reached at initial melanoidin concentration of 1100 mg L−1 (5% dilution), pH 6, and a contact time of 120 min. The Langmuir and Freundlich isotherm models were used to evaluate adsorption isotherms. The maximum adsorption capacity of 281.34 mg/g was observed using the Langmuir isotherm. Furthermore, pseudo-first- and pseudo-second-order and intra-particle diffusion models were used to fit adsorption kinetic data. The pseudo-second-order was best describing the adsorption kinetic with a faster kinetic rate of 0.142 mg g–1 min−1. CFA (coal fly ash) after acidic activation resulted in a slightly higher surface area, average pore volume, and pore size. The maximum breakthrough time and adsorbent saturation time were achieved at initial melanoidin concentration of 1 mol/lit, bed height of 2.5 m, and flow rate of 50 lit/min.
- Published
- 2020
4. Impacts of slurry and dry forms of low-rank coal (lignite) on quality of syngas produced
- Author
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Syed Abdul Karim Shah, Ghulamullah Maitlo, Zulfiqar Ali Bhatti, Rasool Bux Mahar, Shaheen Aziz, Suhail Ahmed Soomro, Mohammad Safar Korai, and Imran Nazir Unar
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Economics and Econometrics ,Environmental Engineering ,Municipal solid waste ,Wood gas generator ,Waste management ,business.industry ,020209 energy ,Biomass ,Fraction (chemistry) ,02 engineering and technology ,010501 environmental sciences ,Management, Monitoring, Policy and Law ,Raw material ,01 natural sciences ,General Business, Management and Accounting ,0202 electrical engineering, electronic engineering, information engineering ,Slurry ,Environmental Chemistry ,Environmental science ,Coal ,business ,0105 earth and related environmental sciences ,Syngas - Abstract
Gasification is one of the prominent and technically efficient technologies for converting solids like coal, biomass or solid waste into useful gas known as “syngas.” Several configurations are in use today among which entrained flow gasifiers have several advantages over other configurations. Presently research is more focused on micro-level modifications in the configurations which have a significant impact on overall performance of gasification. Scant, literature is available for comparison of slurry over dry form of feedstocks, especially with low-grade coals. Hence, present research aims to establish a concrete finding regarding the impacts of slurry versus the dry condition of coal on the overall performance of gasification. To achieve this goal, a two-dimensional computational fluid dynamic (CFD) model of downdraft gasifier was developed in commercial CFD software FLUENT for performing numerical simulations with indigenous coal feedstock. Rich oxidant conditions (95% oxygen and 5% nitrogen) were maintained in the gasifier for the gasification. The performance of gasification was measured by comparing efficiencies of gasification and the quality of syngas produced with different coal forms. As per simulation results, coal forms and operating conditions caused a significant effect on overall gasification performance. In syngas composition, H2 mol fraction reached at maximum, when the slurry form of coal was used for gasification. This effect is remarkable for generating hydrogen-rich fuel from lignite without consuming steam externally.
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- 2020
5. Citronellal cyclisation to isopulegol over micro-mesoporous zsm-5 zeolite: effects of desilication temperature on textural and catalytic properties
- Author
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Aqeel Ahmed Shah, Hassnain Abbas Khan, Rashid Mustafa Korai, Abdul Karim Shah, Imran Nazir Unar, Syed Farman Ali Shah, Usama Ismail, Ghulamullah Maitlo, and Yeung Ho Park
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010405 organic chemistry ,Chemistry ,010402 general chemistry ,01 natural sciences ,Catalysis ,0104 chemical sciences ,Reaction rate ,chemistry.chemical_compound ,Adsorption ,Chemical engineering ,Citronellal ,Lewis acids and bases ,Physical and Theoretical Chemistry ,Mesoporous material ,Selectivity ,Zeolite - Abstract
In this work, desilication reassembly post treatment process was applied in synthesis of mesoporous zeolite with stable phase composition and applied it in citronellal cyclisation reaction for the production of isopulegol. The desilication and temperature effects were further investigated on physical and chemical characteristics of zeolite and compared them with catalytic activity. The desilicated zeolite samples have been characterized with the help of N2-adsorption, XRD, ICP-OES, pyridine adsorption and FTIR techniques. Its performance was explored by controlling operative parameters. Experimental outcomes exhibited that desilication of zeolite would led to formation of mesopores inside the stable zeolite framework structures without substantial damage of their internal composition. These changes facilitate mass transfer and catalytic activity with an increase in surface area, mesoporosity, pore size, pore volume, acidity, and Lewis acid sites. Optimum desilication temperature (80 °C) was found as a best for an comprising extra active and selective mesoporous zeolite catalyst for citronellal cyclisation. Thus, this type of zeolite material has shown 100% conversion (e.g. complete conversion of citronellal reactants to the desired products), 95% isopulegol selectivity and highest reaction rate (0.11 min−1). This study exhibits the mesoporous zeolite (MZ-80 °C) as one of the most effective catalyst for citronellal cyclization reaction based on assessment of catalytic performance relative to other commonly available options.
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- 2019
6. Thermogravimetric analysis of Pakistani biomasses using nitrogen and oxygen as a carrier gas
- Author
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Imran Nazir Unar, Syed Abdul Karim Shah, and Ghulamullah Maitlo
- Subjects
Thermogravimetric analysis ,General Chemical Engineering ,Analytical chemistry ,chemistry.chemical_element ,02 engineering and technology ,General Chemistry ,Activation energy ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Biochemistry ,Nitrogen ,Husk ,Industrial and Manufacturing Engineering ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,visual_art ,Materials Chemistry ,visual_art.visual_art_medium ,Hemicellulose ,Sawdust ,Cellulose ,0210 nano-technology ,Pyrolysis - Abstract
Thermochemical characterization of four different biomasses sawdust (SD), rice husk (RH), cotton stalk (CS) and sugarcane bagasse (SB) was investigated to understand their kinetic characteristics. The TGA experiments were done using inert and oxidative atmospheres to understand the reaction kinetics of selected biomasses. The temperature was enlarged from room temperature to 900 °C at a heating rate of 10 °C min−1 under non-isothermal conditions. The weight loss of all the four biomass materials under an inert and oxygen environments showed alike weight loss trend occurring in three main stages. It was observed that all four biomass materials degraded in three identical regions. In the first region of weight loss, moisture evaporation was observed, in second region cellulose and hemicellulose degradation was achieved, whereas in third region lignin degradation was achieved under both an inert and oxy-combustion atmospheres at different temperature ranges. The activation energy, pre-exponential factors were evaluated through Arrhenius correlation equations. The values of E calculated during pyrolysis for CS, SB, SD and RH were 79.10, 68.32, 53.46, 52.9 (kJ mol−1) during oxy-combustion atmospheres 122.6, 106.31, 123.28 and 118 (kJ mol−1), respectively.
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- 2018
7. Performance evaluation of solar flat plate collector using different working fluids through computational fluid dynamics
- Author
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Imran Nazir Unar, Abdul Sattar Jatoi, Abdul Qayoom Memon, Ghulam Abbas Kandhro, Syed Saad Ali, Ghulamullah Maitlo, and Shoaib Ahmed
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Thermal efficiency ,Materials science ,business.industry ,Turbulence ,General Chemical Engineering ,General Engineering ,Turbulence modeling ,General Physics and Astronomy ,Mechanics ,Computational fluid dynamics ,Volumetric flow rate ,Physics::Fluid Dynamics ,Continuity equation ,Physics::Space Physics ,General Earth and Planetary Sciences ,Working fluid ,General Materials Science ,Ray tracing (graphics) ,Astrophysics::Earth and Planetary Astrophysics ,business ,General Environmental Science - Abstract
The aim of this study involves establishing a three-dimensional computational fluid dynamic (3D-CFD) model of solar flat plate collector (SFPC) in order to investigate the effect of operating and geometric parameters on thermal efficiency. In this research work, commercial CFD code ANSYS FLUENT®14.0 version was used for the development of a model of solar plate collector. The single circular tube geometry was created using ANSYS DesignModeler®14.0. The general continuity equation along with Navied–Stokes equations was solved for tracking motion of the working fluid. The general k–e turbulence modeling approach was used for solving the turbulence in the flow. Solar ray tracing was activated for calculating solar load in the model. The latitude and longitude of the Hyderabad region were inserted in the solar ray-tracing model for calculating solar intensity as per local conditions. Two fluids i.e., water and air were circulated with different flow rates in the developed model of SFPC. It was observed that water gave higher efficiency due to high density and thermal conductivity. The simulation results gathered revealed that the temperature of water and air was raised by almost 79 °C and 73 °C respectively.
- Published
- 2020
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