Department of Process Engineering (1992 - Present)
Chemical Engineering
, Leeds University, Leeds , England
Chemical Engineering
, Ottawa University, Ottawa , Canada
Chemical Engineering
, University of Tehran, Tehran, Iran
Dr. Hassan Pahlavanzadeh was born in 1956 in Ghazvin, Iran. He is full professor in chemical engineering faculty of Tarbiat Modares University. He got his Bachelor of engineering, MsC and PhD. degrees in chemical engineering from Tehran University , Ottawa University(Canada) and Leeds University(England) respectively. His favourite research fields are as: Gas hydrate formation- Gas solubility in liquids (Gas sweetning)- Heavy metal adsorption and Energy and exergy analysis.
In this study, the thermal, mechanical, and chemical equilibrium conditions are derived for binary solid–liquid equilibrium under the effect of an electric field. As an example, the effect of an electric field on the water/glycerol solid–liquid phase diagram is computed over the complete mole fraction range. We show that the application of an electric field can affect the composition dependent freezing and precipitating processes, changing freezing and precipitating temperatures and changing the eutectic point temperature and mole fraction.
As noted by Deng in the Comment, Comsol software does not simply apply the boundary condition 1. Of course, this can be done by writing a function and coupling, but considering that the L/D ratio of the tubes is very high, it can be assumed that the concentration has reached a constant level in the end of tubes, which means that boundary condition 2 is acceptable. In this study, 1 we also used the Comsol outflow boundary condition, and boundary condition 1 is incorrectly given in this manuscript. This boundary condition is also true, of course, and we have seen it in previous research, 2, 3 but this condition has been used more in research done with MATLAB software.
The intended object of this research was to evaluate the influence of different parameters employed on the form-stable phase change materials (FSPCMs) characteristics, with emphasis on the loading percentage of a phase change material (PCM) into the supporting material layers. A melt impregnation process was established to fabricate the FSPCM composites. Stearic acid (SA), one of the fatty acids included in the vegetable oils, possessed various properties suitable as a renewable PCM and was used to be impregnated into kaolin as the supporting material that comes from the clay-based mineral group. Mesh size of kaolin, PCM mass fraction, impregnation time, and temperature were among the studied parameters that took part in the loading percent
Experimental and thermodynamic modeling results for hydrate dissociation conditions in carbon dioxide + THF + NaCl + water systems were reported. Four different aqueous solutions of THF and NaCl (0.05 mass fraction of NaCl, 0.05 mass fraction of THF: namely solution 1; 0.10 mass fraction of NaCl, 0.05 mass fraction of THF: namely solution 2; 0.05 mass fraction of NaCl, 0.20 mass fraction of THF: namely solution 3; 0.10 mass fraction of NaCl, 0.20 mass fraction of THF: solution 4) were studied in this work. An isochoric pressure – search method was used to perform the measurements. The equilibrium dissociation conditions are reported in the ranges of (0.92–3.89) MPa and (280.9–292.9 K). NaCl acts as an inhibitor in all of
In the current study, the effect of tetra-n-butyl ammonium bromide (TBAB) and cyclohexane mixture on CH4 semi-clathrate hydrate formation was studied. Semi-clathrate dissociation conditions for CH4?+?TBAB?+?cyclohexane?+?water were investigated at different concentrations of TBAB (0.05, 0.10, and 0.15) mass fraction in the presence of cyclohexane at the pressure and temperature ranges of 1–8?MPa and 275.1–295?K, respectively. In addition, a thermodynamic model was suggested to predict the phase equilibria of our system, which is divided into four phases, where the van der Waals–Platteeuw Solid Solution Theory has been used to predict the hydrate phase. For gas phase, The SRK equation of state was applied. For oil phase, the cyclohexan
Gas hydrates, or clathrate hydrates, can be used as a suitable cold/cool storage media, due to their large phase change enthalpy. In recent decades, cold production through gas hydrates as a novel and cost-effective method has motivated researchers. Refrigerants have the potential to be used in hydrate-based cold storage systems, because they can form hydrates at moderate pressures and temperatures. Hence, in this work, the kinetics of R410a (50 wt% difluoromethane + 50 wt% 1,1,1,2,2-pentafluoroethane) hydrate formation in the presence of different concentrations of SDS, tween 20, and graphene oxide (GO) was investigated. The experiments were carried out in a 300 cm3 reactor/cell at the initial pressure and temperature of 1 MPa
Available water for the formation of natural gas hydrate at the industrial scale is normally saline water in which the dissolved salts inhibit the hydrate formation. To overcome this challenge, thermodynamic promoters can be used. In the present work, hydrate phase equilibria of methane + mixed promoters of tetrahydrofuran (THF) and tetra-n-butyl ammonium bromide (TBAB) were investigated in the absence and presence of NaCl, MgCl2, and NaCl + MgCl2 aqueous solutions. The phase equilibrium data, which were generated using an isochoric pressure-search method with a step heating technique, are reported in the pressure and temperature ranges of 1.09-5.16 MPa and 286.0-299.0 K, respectively. Equilibrium data show that an aqueous mixture of THF +
This research presents a 2D mathematical modeling based on finite difference method (FDM) for absorption of CO2 into aqueous solution of ionic liquids ([bmim][BF4] and [bmim][PF6]) by means of hydrophobic polypropylene hollow fiber membrane contactor (HFMC). Governing equations with their corresponding boundary conditions were solved and the results were validated against reported experimental data and excellent agreement was found. This study has provided an opportunity to investigate the effects of various ionic liquids with different concentrations as well as liquid and gas flow rate on CO2 absorption system in membrane contactors. The results demonstrated that molar flux of carbon dioxide for 25 wt% and 50 wt% solution of [bmim][PF6] is
In this communication, experimental data of hydrate dissociation conditions for (CO2 + tetra nbutylammonium chloride (TBAC) + cyclopentane (CP) + water) system is reported in the temperature range of (286-293) K, the pressure range of (0.97-3.51) MPa, and at various concentrations of TBAC (0.05, 0.10, 0.18 and 0.25 mass fractions). The experiments were carried out using an isochoric pressure-search method to obtain the experimental data and the method validity was checked by regenerating (CO2 + TBAC) hydrate data reported in literature. A thermodynamic model was developed to estimate the experimental hydrate dissociation conditions, which employs e-NRTL activity coefficient model and PR equation of state to model the liquid and the vapor/g
For the first time, numerous experiments were carried out to evaluate the effect of electric field (EF) on the mechanism of naturally occurring THF hydrate formation. The Statistical Package for the Social Sciences (SPSS) software was utilized to analyze the experimental data. First, the effect of static electric field (SEF) strength on nucleation temperature (T-nuc) and growth time (t-growth) studied. Based on the statistical results, increasing the intensity of SEF induces nucleation at a relatively high temperature. Furthermore, the completion of solidification takes a longer time than the same process in the absence of SEF. The notable point is that by switching a SEF to a pulsed electric field (PEF) of equal voltage, the EF effectivene
In this communication, the promoting effects of two additive mixtures (cyclopentane + TBANO3) on CH4 hydrate phase equilibrium were experimentally investigated using the isochoric method. The mass fractions of TBANO3 employed in this paper were 5, 10, 15, and 20. The results showed that cyclopentane is a good promoter in comparison with pure water + CH4 systems, and TBANO3 has a promoting effect but not like cyclopentane in compassion with pure water + CH4 systems. Additionally, the mixture of cyclopentane + TBANO3 has an important promoting effect in comparison with pure water and TBANO3 + water + CH4 systems, but it has a less promoting effect in comparison with cyclopentane + water + CH4 systems. Furthermore, a new thermodynamic model wa
Separation of sulfur dioxide by a new environmentally friendly method through its reduction to sulfur was investigated. Nickel catalyst was synthesized on two bases of alumina and activated carbon, using a wet impregnation method. Both catalyst series in two combinations of different percentages of nickel metal were synthesized, characterized and their performance in the reactor test in terms of conversion rate and selectivity for the desired product were compared. The effect of reaction temperature was investigated in the range of 550-800 C. At low temperatures, activated carbon-nickel catalysts have better performance than the alumina-nickel catalyst. Effect of molar feed ratio of SO2/CH4= 3-1 was studied and stoichiometric feed ratio sho
The current study provides experimental data and thermodynamic modeling of hydrate stability conditions of CO2 + tetra n-butylphosphonium bromide (TBPB) + cyclopentane (CP) + water system. The experimental results are presented from (288 to 292) K and (1.45 to 3.30) MPa at 0.10, 0.15, 0.17, and 0.20 mass fractions of TBPB in aqueous solutions. To measure the experimental data, an isochoric step-heating pressure-search method was applied. The validity of the method used in the current study was evaluated by regenerating previously reported experimental data on hydrate dissociation conditions of the carbon dioxide + TBPB + water system. The experimental results reveal that mixed promoters of TBPB + CP have the promotion effect compared to car
Gas hydrate technology has a great potential for natural gas storage and transportation on the industrial scale. The required water for hydrate formation could be supplied from the sea and river water, in which the dissolved salts inhibit the formation of hydrate. Some additives like tetra-n-butyl ammonium chloride (TBAC), which can form semiclathrate structures, can promote the thermodynamic stability conditions of hydrate formation. Although sufficient phase equilibrium data of TBAC semiclathrate hydrates of methane seem to be available, there are some discrepancies in the phase equilibrium data, particularly for the 0.05, 0.3, and 0.34 mass fractions of TBAC. Furthermore, the phase equilibrium data of TBAC in the presence of NaCl, MgCl2,
Serious issues regarding the scarcity of freshwater encouraged researchers to work on various methods for seawater desalination. Hydrate-based desalination (HBD) is a novel method that has received investigators’ attention due to its outstanding properties. According to the literature, refrigerant hydrates have great potential to be employed in the HBD process because of their highly moderate phase equilibrium. The main purpose of the current study is to investigate the influence of different concentrations of NaCl (0, 1, 3.5, 5, and 8 wt %) on the major kinetic parameters of R410a refrigerant hydrate formation in the presence and absence of cyclopentane with the concentration of 0.5 mol % as a coformer. The experiments were performed in
Copper ion Cu(II) as a toxic and carcinogenic component can be deposited in liver resulting in subsequent abdominal pain, respiratory problems, liver and kidney failure. According to US Environmental Protection Agency, the maximum Cu(II) should be below 1.3 mg/L in industrial effluents. Cu(II) must be removed from wastewaters before disposal. Dead green algae Schizomeris leibleinii, an abundant solid waste, was applied as a novel sorbent for Cu(II) removal from aqueous solutions. Experimental factors including initial pH, contact time, adsorbent dosage, initial copper concentration and temperature were studied. FTIR and FE-SEM/EDS analyses were performed before and after adsorption. The maximum adsorption capacity was 55.06 mg/g obtained at
The effects of addition of an ionic liquid to pure water as a physical absorbent and monoethanolamine (MEA) solutions as a chemical absorbent on carbon dioxide (CO2) absorption through hollow fiber membrane contactors were investigated using a 2D axisymmetric model. A numerical simulation was developed based on finite element method using computational fluid dynamics techniques. Liquid phase flowed in the tube side and gas mixture containing CO2 passed in the shell side of the membrane contactor in co-current and countercurrent modes. The simulation results are consistent with experimental data, and the root-mean-square error was calculated as 9 and 13% for pure water and 25 wt % for ionic liquid solution. The results showed that addition o
Due to the contamination of freshwater resources, numerous techniques have been designed to address the challenges in achieving desalinated or freshwater over the past 50 years. Hydrate-based desalination (HBD) is one of the low-cost and efficient technologies receiving considerable interest of investigators in recent decades. Since R410a has the ability to form hydrates at mild conditions, in this research, three-stage desalination of synthesized seawater using R410a hydrate formation was carried out. The experiments were perormed in a stirred reactor at initial conditions of 11, 10, and 9 bar and 275.15 K. Moreover, cyclopentane was selected as a coformer for desalination experiments in the case of 9 bar. The desalination results showed t
Gas hydrate, or clathrate hydrate, technology is considered to be one of the promising solutions for natural gas storage and transportation. Tetrabutylphosphonium bromide (TBPB) is capable of sorting out stability issues of hydrate formation effectively. On the other hand, using water from natural resources such as sea, river, or well instead of pure water is essential for hydrate formation in the industrial scale. The current study was organized to investigate the hydrate phase behaviors of CH4 + TBPB formed in saline solutions, which are necessary for potential industrial applications. For this purpose, we first generated hydrate dissociation conditions data of the CH4 + TBPB aqueous solution system over TBPB mass fractions of 0.05 and 0.
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