Khashayar Nasrifar - Academia.edu (original) (raw)
Papers by Khashayar Nasrifar
Journal of Molecular Liquids, 2022
Fluid Phase Equilibria, 2021
Abstract Saline water and organic inhibitors have considerable effects on preventing the formatio... more Abstract Saline water and organic inhibitors have considerable effects on preventing the formation of clathrate hydrates in gas and oil industries. The purpose of this study was to demonstrate a model that is capable of estimating the effects of NaCl, KCl, CaCl2 and methanol aqueous solutions on the equilibrium dissociation conditions of pure and gas mixture hydrates in wide ranges of pressure and temperature. The e-NRTL activity coefficient model is employed to describe the non-ideally of the liquid/aqueous phase. The solid solution theory of van der Waals and Platteeuw is applied to characterize the hydrate phase. The gas phase is described by the Peng-Robinson (PR) equation of state. No adjusting or fitting parameter is used. A comprehensive evaluation of the estimated values and literature data reveals the great accuracy of this model. To give a definite opinion, the obtained results of the proposed model were compared to experimental data and the results of four other thermodynamic models where the e-NRTL based model exhibits the least average absolute deviation (AAD). The average AAD of the e-NRTL based model results over 828 experimental data points was determined to be 0.59 K, which demonstrates an excellent agreement between the experimental data and the predicted/estimated values.
Hydrocarbon Processing, 1999
An accurate model is extended to include gases in the presence of glycerol and triethylene glycol... more An accurate model is extended to include gases in the presence of glycerol and triethylene glycol solutions.
In this contribution, two approaches are followed to predict the saturated liquid density of liqu... more In this contribution, two approaches are followed to predict the saturated liquid density of liquefied natural gas (LNG) mixtures. In one approach, 12 cubic equations of state (EoSs), comprising the popular Peng-Robinson (PR) and Redlich-Kwong-Soave (RKS), are employed to predict the saturated liquid density of 20 LNG mixtures. In the other approach, these EoS are used in conjunction with a recently developed correlation to predict the liquid density of the same LNG mixtures. This correlation takes the advantages of the EoSs functions and is remarkably accurate for LNG mixtures. The results for both approaches are presented and the best predicting methods are ranked. Also the liquid density of 3 gas condensate mixtures are predicted using 10 EoSs and the results are compared with experimental data. The method employed is discussed and the best EoSs are ranked. Our evaluation indicates that in general, the EoSs used in this study are not accurate enough for predicting the liquid dens...
ABSTRACT We develop an unsteady two-equation model which describes the water flow in unsaturated ... more ABSTRACT We develop an unsteady two-equation model which describes the water flow in unsaturated zones. The governing equations are based on general conservation laws of mass and momentum. Although the obtained equations are not amenable to being solved by analytical means, a control volume numerical solution using upwind scheme can be employed. In order to test the model equations, two examples of one- and two-dimensional water infiltration are simulated. The effects of discretization on spatial and temporal coordinates are demonstrated. Also, the results are compared with results of previous studies.
This work deals with estimation of temperature dependent binary interaction parameters (kij) for ... more This work deals with estimation of temperature dependent binary interaction parameters (kij) for binary systems containing CO2 using the Soave-Redlich-Kwong equation of state with a group contribution method. In this paper six groups, namely CH3, CH2, CH, CH4 (methane), C2H6 (ethane), and CO2 (carbon dioxide) are defined and their relevant values of group interaction parameters are optimized. Using this method, it is possible to estimate the kij of any mixture containing carbon dioxide and hydrocarbons at any temperature along the coexistence curve. The results obtained in this study are, in most cases, accurate.
Journal of Solution Chemistry
Using Henry’s law constant, we applied a previously developed approach to the Peng–Robinson (PR) ... more Using Henry’s law constant, we applied a previously developed approach to the Peng–Robinson (PR) and Soave–Redlich–Kwong (SRK) equations of state in deriving formulas for the binary interaction parameters of van der Waals mixing rules. The formulas are solely temperature dependent and require the Henry’s law constant of a gas in water in addition to the critical temperatures, critical pressures and acentric factors of the gas and water. The method was successfully used to predict the solubility of methane, ethane, propane, hydrogen sulfide, carbon dioxide, argon, krypton, xenon and nitrogen in water for wide ranges of temperature and pressure. Among the equations of state, PR was found to have the best performance with average absolute deviation of 5.2%. In addition, PR was employed to predict the solubility of gas mixtures in water, including methane + ethane, methane + n-butane and methane + ethane + n-butane at pressures up to 100 MPa. The accuracy of predictions was found to be comparable to those of the solubilities of pure gases in water.
Journal of Natural Gas Science and Engineering
Abstract Many applications dealing with carbon dioxide are limited because of carbon dioxide fros... more Abstract Many applications dealing with carbon dioxide are limited because of carbon dioxide frosting. Therefore, it has been important to accurately predict the temperature where carbon dioxide solidifies. In this work, using solid – vapor (SV) equilibria, the frost points of binary and ternary model systems resembling natural gases – that are, methane + carbon dioxide, nitrogen + methane + carbon dioxide and methane + ethane + carbon dioxide are predicted by the predictive Peng-Robinson 1978 (PPR78), Redlich-Kwong-Soave (RKS), Nasrifar-Bolland (NB) equations of state and a solid fugacity relation. The equations of state are used to describe the vapor phase in SV equilibria. Accordingly, the equations of state are coupled with a group-contribution temperature-dependent binary interaction parameter that was previously developed from vapor – liquid (VL) equilibria. The solid fugacity relation was developed in this work for describing solid carbon dioxide. The solid fugacity relation expands around the triple point temperature of carbon dioxide. It is explicit in temperature and pressure and needs triple point temperature and sublimation enthalpy of carbon dioxide as input parameters. The model is fully predictive and does not require any adjustable parameter. When the NB equation of state with the solid fugacity relation was applied to natural gas model systems (NGMS), the agreement with experiments was found satisfactory. The NGMS contained 0.1%–54.2% carbon dioxide, temperature and pressure ranged from 140 K to 216 K and 100 kPa–3500 kPa, respectively. The effects of nitrogen and ethane on the frost point were also evaluated and the model accuracy was found adequate. Average absolute deviation (AAD) in predicting 291 experimental frost points for binary and ternary mixtures containing carbon dioxide was found to be 1.58 K.
Journal of Molecular Liquids
Abstract A simple and accurate generalized correlation for calculating the liquid densities of io... more Abstract A simple and accurate generalized correlation for calculating the liquid densities of ionic liquids (ILs) at 0.1 MPa is proposed by modifying a previously developed liquid density correlation for refrigerants. With no adjustable parameter and for a wide range of temperature commonly used in IL applications, the percent average absolute deviation (%AAD) in calculating 1036 liquid density data points for 52 ILs was found to be 1.54%. To perform calculations, the developed model employs the critical temperature, the critical density and the acentric factor of ILs. When compared with 9 other generalized correlations, the new correlation was found to be superior. The %AAD for the next best correlation for the same temperature range and number of data points was found to be 2.35%. At pressures well above 0.1 MPa and for a wide temperature range, the developed correlation of this work was coupled with seven relationships for predicting the liquid densities of ILs at high pressures. The best relationships were found to be the ones developed by Tait, Chang and Zhao (CZ) and Nasrifar and co-workers (NAM) in predicting the liquid densities of 41 ILs comprising 6093 data points. The %AAD was found to be 2.08%, 2.10% and 2.13%, respectively, for coupling of the new generalized correlation with the relationships provided by Tait, CZ and NAM.
Fluid Phase Equilibria
Abstract Water contents of synthetic sweet and sour natural gas–like mixtures and their constitue... more Abstract Water contents of synthetic sweet and sour natural gas–like mixtures and their constituents for wide ranges of temperature and pressure are studied in this work. The perturbed-chain version of statistical associated fluid theory (PC-SAFT) is used to describe the vapor and aqueous phase. In addition to repulsion and dispersion interactions, the 4C association scheme is used to account for self-association between water molecules. Using the PC-SAFT approach, the water contents of methane, ethane, hydrogen sulfide, carbon dioxide, and certain synthetic sweet and sour natural gas mixtures are predicted satisfactorily.
Journal of Natural Gas Science and Engineering, 2016
Abstract A simulation was conducted using Aspen HYSYS ® software for an industrial scale condensa... more Abstract A simulation was conducted using Aspen HYSYS ® software for an industrial scale condensate stabilisation unit and the results of the product composition from the simulation were compared with the plant data. The results were also compared to the results obtained using PRO/II software. It was found that the simulation is closely matched with the plant data and in particular for medium range hydrocarbons. The effects of four process conditions, i.e. feed flow rate, temperature, pressure and reboiler temperature on the product Reid Vapour Pressure (RVP) and sulphur content were also studied. The operating conditions which gave rise to the production of off-specification condensate were found. It was found that at a column pressure of 8.5 barg and reboiler temperature of 180 °C, the condensate is successfully stabilized to a RVP of 60.6 kPa (8.78 psia). It is also found that as compared to the other parameters the reboiler temperature is the most influential parameter control the product properties. Among the all sulphur contents in the feed, nP-Mercaptan played a dominant role for the finishing product in terms of sulphur contents.
Fluid Phase Equilibria, 2015
Petroleum Science and Technology
Journal of Molecular Liquids
Industrial & Engineering Chemistry Research
Chemical Engineering Research and Design
The formation of gas hydrate shows good potential to work as a separation medium for gas mixtures... more The formation of gas hydrate shows good potential to work as a separation medium for gas mixtures. However, to put it in practice, the impact of process parameters, such as flow rates, operational temperature and pressure are required to be adequately investigated. In this work, a new gas hydrate reactor is introduced for fast production of gas hydrate. The reactor is used for separation of carbon dioxide from methane in a series of semi-batch experiments. Results indicated that fast hydrate production is achievable. In addition, carbon dioxide is effectively separated from methane by producing gas hydrate from a gas mixture containing more than 60% carbon dioxide.
Oil & Gas Sciences and Technology – Revue d’IFP Energies nouvelles
Three equations of state with a group contribution model for binary interaction parameters were e... more Three equations of state with a group contribution model for binary interaction parameters were employed to calculate the vapor-liquid equilibria of synthetic and real natural gas mixtures with heavy fractions. In order to estimate the binary interaction parameters, critical temperatures, critical pressures and acentric factors of binary constituents of the mixture are required. The binary interaction parameter model also accounts for temperature. To perform phase equilibrium calculations, the heavy fractions were first discretized into 12 Single Carbon Numbers (SCN) using generalized molecular weights. Then, using the generalized molecular weights and specific gravities, the SCN were characterized. Afterwards, phase equilibrium calculations were performed employing a set of (nc + 1) equations where nc stands for the number of known components plus 12 SCN. The equations were solved iteratively using Newton's method. Predictions indicate that the use of binary interaction paramet...
The Canadian Journal of Chemical Engineering
Journal of Molecular Liquids, 2022
Fluid Phase Equilibria, 2021
Abstract Saline water and organic inhibitors have considerable effects on preventing the formatio... more Abstract Saline water and organic inhibitors have considerable effects on preventing the formation of clathrate hydrates in gas and oil industries. The purpose of this study was to demonstrate a model that is capable of estimating the effects of NaCl, KCl, CaCl2 and methanol aqueous solutions on the equilibrium dissociation conditions of pure and gas mixture hydrates in wide ranges of pressure and temperature. The e-NRTL activity coefficient model is employed to describe the non-ideally of the liquid/aqueous phase. The solid solution theory of van der Waals and Platteeuw is applied to characterize the hydrate phase. The gas phase is described by the Peng-Robinson (PR) equation of state. No adjusting or fitting parameter is used. A comprehensive evaluation of the estimated values and literature data reveals the great accuracy of this model. To give a definite opinion, the obtained results of the proposed model were compared to experimental data and the results of four other thermodynamic models where the e-NRTL based model exhibits the least average absolute deviation (AAD). The average AAD of the e-NRTL based model results over 828 experimental data points was determined to be 0.59 K, which demonstrates an excellent agreement between the experimental data and the predicted/estimated values.
Hydrocarbon Processing, 1999
An accurate model is extended to include gases in the presence of glycerol and triethylene glycol... more An accurate model is extended to include gases in the presence of glycerol and triethylene glycol solutions.
In this contribution, two approaches are followed to predict the saturated liquid density of liqu... more In this contribution, two approaches are followed to predict the saturated liquid density of liquefied natural gas (LNG) mixtures. In one approach, 12 cubic equations of state (EoSs), comprising the popular Peng-Robinson (PR) and Redlich-Kwong-Soave (RKS), are employed to predict the saturated liquid density of 20 LNG mixtures. In the other approach, these EoS are used in conjunction with a recently developed correlation to predict the liquid density of the same LNG mixtures. This correlation takes the advantages of the EoSs functions and is remarkably accurate for LNG mixtures. The results for both approaches are presented and the best predicting methods are ranked. Also the liquid density of 3 gas condensate mixtures are predicted using 10 EoSs and the results are compared with experimental data. The method employed is discussed and the best EoSs are ranked. Our evaluation indicates that in general, the EoSs used in this study are not accurate enough for predicting the liquid dens...
ABSTRACT We develop an unsteady two-equation model which describes the water flow in unsaturated ... more ABSTRACT We develop an unsteady two-equation model which describes the water flow in unsaturated zones. The governing equations are based on general conservation laws of mass and momentum. Although the obtained equations are not amenable to being solved by analytical means, a control volume numerical solution using upwind scheme can be employed. In order to test the model equations, two examples of one- and two-dimensional water infiltration are simulated. The effects of discretization on spatial and temporal coordinates are demonstrated. Also, the results are compared with results of previous studies.
This work deals with estimation of temperature dependent binary interaction parameters (kij) for ... more This work deals with estimation of temperature dependent binary interaction parameters (kij) for binary systems containing CO2 using the Soave-Redlich-Kwong equation of state with a group contribution method. In this paper six groups, namely CH3, CH2, CH, CH4 (methane), C2H6 (ethane), and CO2 (carbon dioxide) are defined and their relevant values of group interaction parameters are optimized. Using this method, it is possible to estimate the kij of any mixture containing carbon dioxide and hydrocarbons at any temperature along the coexistence curve. The results obtained in this study are, in most cases, accurate.
Journal of Solution Chemistry
Using Henry’s law constant, we applied a previously developed approach to the Peng–Robinson (PR) ... more Using Henry’s law constant, we applied a previously developed approach to the Peng–Robinson (PR) and Soave–Redlich–Kwong (SRK) equations of state in deriving formulas for the binary interaction parameters of van der Waals mixing rules. The formulas are solely temperature dependent and require the Henry’s law constant of a gas in water in addition to the critical temperatures, critical pressures and acentric factors of the gas and water. The method was successfully used to predict the solubility of methane, ethane, propane, hydrogen sulfide, carbon dioxide, argon, krypton, xenon and nitrogen in water for wide ranges of temperature and pressure. Among the equations of state, PR was found to have the best performance with average absolute deviation of 5.2%. In addition, PR was employed to predict the solubility of gas mixtures in water, including methane + ethane, methane + n-butane and methane + ethane + n-butane at pressures up to 100 MPa. The accuracy of predictions was found to be comparable to those of the solubilities of pure gases in water.
Journal of Natural Gas Science and Engineering
Abstract Many applications dealing with carbon dioxide are limited because of carbon dioxide fros... more Abstract Many applications dealing with carbon dioxide are limited because of carbon dioxide frosting. Therefore, it has been important to accurately predict the temperature where carbon dioxide solidifies. In this work, using solid – vapor (SV) equilibria, the frost points of binary and ternary model systems resembling natural gases – that are, methane + carbon dioxide, nitrogen + methane + carbon dioxide and methane + ethane + carbon dioxide are predicted by the predictive Peng-Robinson 1978 (PPR78), Redlich-Kwong-Soave (RKS), Nasrifar-Bolland (NB) equations of state and a solid fugacity relation. The equations of state are used to describe the vapor phase in SV equilibria. Accordingly, the equations of state are coupled with a group-contribution temperature-dependent binary interaction parameter that was previously developed from vapor – liquid (VL) equilibria. The solid fugacity relation was developed in this work for describing solid carbon dioxide. The solid fugacity relation expands around the triple point temperature of carbon dioxide. It is explicit in temperature and pressure and needs triple point temperature and sublimation enthalpy of carbon dioxide as input parameters. The model is fully predictive and does not require any adjustable parameter. When the NB equation of state with the solid fugacity relation was applied to natural gas model systems (NGMS), the agreement with experiments was found satisfactory. The NGMS contained 0.1%–54.2% carbon dioxide, temperature and pressure ranged from 140 K to 216 K and 100 kPa–3500 kPa, respectively. The effects of nitrogen and ethane on the frost point were also evaluated and the model accuracy was found adequate. Average absolute deviation (AAD) in predicting 291 experimental frost points for binary and ternary mixtures containing carbon dioxide was found to be 1.58 K.
Journal of Molecular Liquids
Abstract A simple and accurate generalized correlation for calculating the liquid densities of io... more Abstract A simple and accurate generalized correlation for calculating the liquid densities of ionic liquids (ILs) at 0.1 MPa is proposed by modifying a previously developed liquid density correlation for refrigerants. With no adjustable parameter and for a wide range of temperature commonly used in IL applications, the percent average absolute deviation (%AAD) in calculating 1036 liquid density data points for 52 ILs was found to be 1.54%. To perform calculations, the developed model employs the critical temperature, the critical density and the acentric factor of ILs. When compared with 9 other generalized correlations, the new correlation was found to be superior. The %AAD for the next best correlation for the same temperature range and number of data points was found to be 2.35%. At pressures well above 0.1 MPa and for a wide temperature range, the developed correlation of this work was coupled with seven relationships for predicting the liquid densities of ILs at high pressures. The best relationships were found to be the ones developed by Tait, Chang and Zhao (CZ) and Nasrifar and co-workers (NAM) in predicting the liquid densities of 41 ILs comprising 6093 data points. The %AAD was found to be 2.08%, 2.10% and 2.13%, respectively, for coupling of the new generalized correlation with the relationships provided by Tait, CZ and NAM.
Fluid Phase Equilibria
Abstract Water contents of synthetic sweet and sour natural gas–like mixtures and their constitue... more Abstract Water contents of synthetic sweet and sour natural gas–like mixtures and their constituents for wide ranges of temperature and pressure are studied in this work. The perturbed-chain version of statistical associated fluid theory (PC-SAFT) is used to describe the vapor and aqueous phase. In addition to repulsion and dispersion interactions, the 4C association scheme is used to account for self-association between water molecules. Using the PC-SAFT approach, the water contents of methane, ethane, hydrogen sulfide, carbon dioxide, and certain synthetic sweet and sour natural gas mixtures are predicted satisfactorily.
Journal of Natural Gas Science and Engineering, 2016
Abstract A simulation was conducted using Aspen HYSYS ® software for an industrial scale condensa... more Abstract A simulation was conducted using Aspen HYSYS ® software for an industrial scale condensate stabilisation unit and the results of the product composition from the simulation were compared with the plant data. The results were also compared to the results obtained using PRO/II software. It was found that the simulation is closely matched with the plant data and in particular for medium range hydrocarbons. The effects of four process conditions, i.e. feed flow rate, temperature, pressure and reboiler temperature on the product Reid Vapour Pressure (RVP) and sulphur content were also studied. The operating conditions which gave rise to the production of off-specification condensate were found. It was found that at a column pressure of 8.5 barg and reboiler temperature of 180 °C, the condensate is successfully stabilized to a RVP of 60.6 kPa (8.78 psia). It is also found that as compared to the other parameters the reboiler temperature is the most influential parameter control the product properties. Among the all sulphur contents in the feed, nP-Mercaptan played a dominant role for the finishing product in terms of sulphur contents.
Fluid Phase Equilibria, 2015
Petroleum Science and Technology
Journal of Molecular Liquids
Industrial & Engineering Chemistry Research
Chemical Engineering Research and Design
The formation of gas hydrate shows good potential to work as a separation medium for gas mixtures... more The formation of gas hydrate shows good potential to work as a separation medium for gas mixtures. However, to put it in practice, the impact of process parameters, such as flow rates, operational temperature and pressure are required to be adequately investigated. In this work, a new gas hydrate reactor is introduced for fast production of gas hydrate. The reactor is used for separation of carbon dioxide from methane in a series of semi-batch experiments. Results indicated that fast hydrate production is achievable. In addition, carbon dioxide is effectively separated from methane by producing gas hydrate from a gas mixture containing more than 60% carbon dioxide.
Oil & Gas Sciences and Technology – Revue d’IFP Energies nouvelles
Three equations of state with a group contribution model for binary interaction parameters were e... more Three equations of state with a group contribution model for binary interaction parameters were employed to calculate the vapor-liquid equilibria of synthetic and real natural gas mixtures with heavy fractions. In order to estimate the binary interaction parameters, critical temperatures, critical pressures and acentric factors of binary constituents of the mixture are required. The binary interaction parameter model also accounts for temperature. To perform phase equilibrium calculations, the heavy fractions were first discretized into 12 Single Carbon Numbers (SCN) using generalized molecular weights. Then, using the generalized molecular weights and specific gravities, the SCN were characterized. Afterwards, phase equilibrium calculations were performed employing a set of (nc + 1) equations where nc stands for the number of known components plus 12 SCN. The equations were solved iteratively using Newton's method. Predictions indicate that the use of binary interaction paramet...
The Canadian Journal of Chemical Engineering