Publication Date: 2016
Desalination and Water Treatment (19443994)57(33)pp. 15285-15292
The performance of humidification-dehumidification desalination, in which dehumidification is carried out by compression, was studied experimentally. A test rig was designed and assembled based on a new idea. In this system, the carrier gas is humidified through direct contact with hot water; and after humidification, the humid air is compressed by a compressor and cooled in a heat exchanger to recover the humidity as desalinated water. The effects of water-to-air ratio, water and air inlet temperatures, operating pressure, and condenser temperature on desalination performance were examined. It was found that the increase in temperature of the feed water and/or inlet air to the humidifier increased the water production rate and gain output ratio (GOR) of the system. The water-to-air ratio showed an increasing-decreasing trend in relation to the water production rate and GOR of the system; the best water-to-air ratio was found to be 2. © 2015 Balaban Desalination Publications. All rights reserved.
Publication Date: 2016
Chemical Engineering Research and Design (17443563)109pp. 180-189
In this article, the reactive absorption of SO2 by seawater is studied in a spray tower experimentally and mathematically. The liquid film formation on the tower wall is implemented in the model and measured experimentally at different operating conditions. The effect of liquid to gas flow rate, initial SO2 concentration in gas phase and initial gas temperature on SO2 removal efficiency is examined. Regarding the importance of liquid droplets hydrodynamics and its effect on the performance of the equipment, the required differential equations for predicting the trajectory and local velocity of droplets are also developed based on the nozzle and spray characteristics and solved simultaneously with other governing equations. In order to survey the effect of nozzle type on removal efficiency, two different types of nozzles are examined. Semi-empirical correlations are proposed for two different nozzles by using experimental data and droplets hydrodynamics model, to predict the amount and the variation of liquid film mass flow rate on the spray tower wall. Results indicate that neglecting the liquid film formation leads to an average of 23% error in predicting the removal efficiency when nozzle type 1 is used, while the calculated error of model by considering the film formation is reduced to 4%. By implementation of droplets hydrodynamics model and applying a modified thermodynamics model for predicting the behavior of the existing chemical reactions, the capability of the spray tower model in predicting the SO2 removal efficiency is enhanced. © 2016 The Institution of Chemical Engineers.
Publication Date: 2015
Process Safety and Environmental Protection (17443598)98pp. 342-353
In the present study, a comprehensive non-isothermal model is developed to study the performance of a spouted bed reactor (SBR), in which CO2 is removed at the presence of SO2 by using NaOH solution. For this aim, the stream-tube model is applied for hydrodynamics of solid and gas phases, and then by using the conservation laws of mass and energy, the governing equations for gas and solid phases are derived and solved numerically. The effects of variation of different operating parameters and process conditions are evaluated, and by comparing the model results with the gathered experimental data, the maximum, minimum and average error are obtained. The results indicate that the CO2 removal efficiency increases by increasing the inlet CO2 concentration and by decreasing the inlet SO2 concentration, ratio of superficial gas velocity to minimum spouting velocity and inlet gas temperature. Also, the modeling overall results indicate that by increasing the bed diameter and static bed height, CO2 absorption efficiency increases. © 2015 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
Publication Date: 2015
Polish Journal of Chemical Technology (18994741)17(3)pp. 13-18
Sweet sorghum juice and traditional ethanol substrate i.e. sugarcane molasses were used for ethanol production in this work. At the end of the fermentation process, the sweet sorghum juice yielded more ethanol with higher ethanol concentration compared to sugarcane molasses in all experiments. The sweet sorghum juice had higher cell viability at high ethanol concentrations and minimum sugar concentration at the end of the fermentation process. The ethanol concentration and yield were 8.9% w/v and 0.45 g/g for sweet sorghum in 80 h and 6.5% w/v and 0.37 g/g for sugarcane molasses in 60 h, respectively. The findings on the physical properties of sweet sorghum juice revealed that it has better physical properties compared to sugarcane molasses, resulting to enhanced performance of sweet sorghum juice for ethanol production © 2015 Mohammad Sadegh Hatamipour et al.
Publication Date: 2015
Chemical Engineering Research and Design (17443563)98pp. 157-167
In a co-current lab-scale spray dryer absorber fitted with a two-fluid nozzle, the removal of carbon dioxide through chemical absorption with NaOH solution as absorbent was investigated experimentally and theoretically. Experimental results showed that in selected ranges of operating parameters, increasing the inlet gas temperature and absorbent concentration has the increasing-decreasing effect on the overall removal efficiency. Also increasing L/G ratio (liquid to gas flow rate), decreasing inlet CO2 concentration and decreasing the droplet mean diameter had favorable effects on overall removal efficiency. Process modeling was done through Computational Fluid Dynamics (CFD) method and using Ansys Fluent 13.0 software. In the three dimensional model of the process the gas phase was modeled as a continuum using the Euler approach and the droplet/particle phase was modeled by the Lagrange approach. An empirical correlation for reaction rate was obtained through experimental data and added to the CFD model of the process as a surface reaction via a user defined function. Predictions of the CFD model were compared to the experimental data. The model prediction in comparison to the experimental trends is fair. © 2015 The Institution of Chemical Engineers.
Publication Date: 2015
Desalination and Water Treatment (19443994)54(6)pp. 1526-1541
The technologies that are used mainly in the seawater desalination industry are reviewed and evaluated in this article. The utilization principles, applications, and problems of these processes are summarized and discussed. The desalination methods are compared with each other for performance ratio (PR), gain output ratio (GOR), unit energy consumption (kWh/m3), or unit operating cost ($/m3) and afterward the preferred method is identified. © 2014, © 2014 Balaban Desalination Publications. All rights reserved.
Publication Date: 2014
Polish Journal of Chemical Technology (18994741)16(4)pp. 60-65
In this study, the thin-layer drying characteristics of Figs (Ficus carica) are investigated in a pilot scale forced convective dryer. Experiments carried out under various operating conditions including air temperature (40, 50, 60, 70°C), air velocity (0.65, 2.1, 3.45, 4.85 m/s) and air humidity (0.005, 0.010, 0.015 kg/kg) and the effects of these operating conditions on the drying kinetics and the drying time determined. The obtained kinetics data are fitted into a conceptually developed model. The equilibrium moisture content of the dried figs is determined at different values of temperature and relative humidity of air. The values of effective moisture diffusivity (Deff) are obtained from the Fick's second law and a temperature-dependent relation is proposed for this parameter. © by A. Rahimi 2014.
Publication Date: 2014
Drying Technology (15322300)32(14)pp. 1655-1663
An image processing technique was used to predict the size distribution of the high speed, fine droplets at downstream of an air blast atomizer. The spray visualization setup consisted of UV lamps as light source, a stroboscope for slowing down the droplet motion, and a digital camera to capture the droplet images. The experiments were carried out at different liquid flow rates with various nozzle diameters. Two key unknown parameters (spray half angle and dispersion angle) of the air blast atomizer model in Fluent were obtained from these experiments. Using the obtained parameters and other structural parameters, the spray modeling was performed, and the Rosin–Rammler distribution was obtained and compared with those obtained from image processing technique through a diagnostic matrix. Regarding the kappa value, the agreement between predictions of the Fluent model and the image processing technique was moderate. © 2014, Copyright Taylor & Francis Group, LLC.
Publication Date: 2014
Desalination (0011-9164)341(1)pp. 120-125
In this communication, a new Humidification De-Humidification process desalination technology is identified which has some advantages (such as: high energy performance, high recovery flow rate, energy recovery and so on) in comparison with other similar methods; this technology is named "Humidification Compression". This method is simulated by a commercial process simulation software and the results are compared with two conventional methods. It is seen that, gain output ratio (GOR) for proposed method is higher than conventional methods; also capital cost per product for proposed method is lower than two others. © 2014 Elsevier B.V.
Amin, M.M.,
Hatamipour, M.S.,
Momenbek, F.,
Nourmoradi, H.,
Farhadkhani, M.,
Mohammadi-moghadam, F. Publication Date: 2014
Scientific World Journal (23566140)2014
The integration of bioventing (BV) and soil vapor extraction (SVE) appears to be an effective combination method for soil decontamination. This paper serves two main purposes: it evaluates the effects of soil water content (SWC) and air flow rate on SVE and it investigates the transition regime between BV and SVE for toluene removal from sandy soils. 96 hours after air injection, more than 97% removal efficiency was achieved in all five experiments (carried out for SVE) including 5, 10, and 15% for SWC and 250 and 500 mL/min for air flow rate on SVE. The highest removal efficiency (>99.5%) of toluene was obtained by the combination of BV and SVE (AIBV: Air Injection Bioventing) after 96 h of air injection at a constant flow rate of 250 mL/min. It was found that AIBV has the highest efficiency for toluene removal from sandy soils and can remediate the vadose zone effectively to meet the soil guideline values for protection of groundwater. © 2014 Mohammad Mehdi Amin et al.
Publication Date: 2014
Chemical Product and Process Modeling (21946159)9(1)pp. 15-24
The performance of a pilot-scale spray dryer is investigated experimentally and theoretically. The governing equations for flow field, heat and mass transfer, and particle trajectory are solved by applying computational fluid dynamics (CFD). The effects of inlet air temperature and initial particle diameter on the outlet humidity and particle residence time are examined. These parameters should be considered carefully in proper designing of spray dryers especially for the heatsensitive products. The model is validated with an error of 5.5%. Copyright © 2011-2014 by Walter de Gruyter GmbH.
Publication Date: 2014
Heat and Mass Transfer (09477411)50(9)pp. 1291-1300
An unsteady-state model is developed for primary and secondary stages of freeze drying process of skim milk. The results are compared with those obtained from a quasi-steady-state (QSS) formulation. The QSS formulation is not valid where the applied heat load is high. The applied heat load affects on the drying time the most compared to other parameters like chamber pressure and the radiation surface temperature. © 2014 Springer-Verlag Berlin Heidelberg.
Publication Date: 2014
Separation Science and Technology (15205754)49(7)pp. 988-998
Flue gas desulfurization of industrial plants using seawater is studied experimentally and theoretically in a counter-current packed-bed tower. Experiments are carried out based on a 16-run orthogonal array of the Taguchi method (five factors, four levels) and ANOVA table created to determine the most significant controlling factors on SO2 removal efficiency. Liquid flow rate (1.5-4 l/min), gas temperature (50-350°C), gas flow rate (8-20 m3/h), and SO2 concentration (500-2000 ppmv) are revealed as important factors, while the pH of seawater (8-9.5) is not significant. Experimental results show that an increase in gas temperature causes a decrease in the removal efficiency. A mathematical model is developed for the removal of SO2 by seawater for non-isothermal operating conditions. In the modeling procedure the equilibrium reactions of eight dissolved species within the liquid phase are considered to calculate the kinetic of reaction correctly. The results of this study confirm the capability of seawater for SO2 removal in packed-bed towers. Copyright © Taylor & Francis Group, LLC.
Publication Date: 2013
International Journal of Thermal Sciences (12900729)74pp. 86-94
This paper is devoted to feasibility study of substitution of two hydrocarbon refrigerants instead of R134a in a domestic refrigerator. Experiments are designed on a refrigerator manufactured for 105 g R134a charge. The effect of parameters including refrigerant type, refrigerant charge and compressor type are investigated. This research is conducted using R436A (mixture of 46% iso-butane and 54% propane) and R600a (pure iso-butane) as hydrocarbon refrigerants, HFC type compressor (designed for R134a) and HC type compressor (designed for R600a). The results show that for HFC type compressor, the optimum refrigerant charges are 60 g and 55 g for R436A and R600a, respectively. Moreover, for this type of compressor, the energy consumption of R436A and R600a at the optimum charges is reduced about 14% and 7%, respectively in comparison to R134a. On the other hand, when using HC type compressor, the optimum refrigerant charges for R436A and R600a are both 50 g, and the energy consumption of R436A and R600a at the optimum charges are reduced about 14.6% and 18.7%, respectively. Furthermore, when the refrigerator is equipped with HC type compressor, working under optimum charges of R436A and R600a have a total equivalent warming impact about 16% and 21% lower than base refrigerator, respectively. Total exergy destruction of the domestic refrigerator with HFC type compressor for R134a, R600a and R436A are 0.0389, 0.0301, 0.0471, respectively and for R600a and R436A with HC type compressor are 0.0292, 0.0472, respectively. © 2013 Elsevier Ltd. All rights reserved.
Publication Date: 2013
Industrial and Engineering Chemistry Research (15205045)52(27)pp. 9422-9432
Previously, several mathematical models have been proposed for liquid-liquid extraction processes involving a rotating-disk-contactor (RDC) column. Most of these models reveal that hydrodynamic and mass-transfer phenomena are important for predicting the performance of the column. In this paper, a mathematical model, using a new scheme, was developed to acquire a simulation tool to predict the performance of a RDC column used in lubricating-oil production. Field data obtained in a RDC column of 4.1 m diameter, 22.2 m height, and 32 disks, from a commercial lubricating-oil production company, were used to evaluate the predictions. The model is used for parametric study to investigate the effects of operational data such as the solvent and feed temperatures, solvent-to-feed ratio, and disk rotation rate on the extraction yield. © 2013 American Chemical Society.
Publication Date: 2013
Journal of Chemical Technology and Biotechnology (02682575)88(7)pp. 1289-1294
Background: A mathematical modeling approach was used to obtain a simulation model to predict the performance of an industrial rotating disc contactor (RDC) in the extraction of lubricating base oils by furfural. The field data of a lube-oil producing plant was used to validate the model. This model can be used for the parametric study of the RDC column and to investigate the effect of operational data such as solvent and feed temperatures, solvent to feed ratio, and agitation rate on the yield of extraction and on the energy saving value of the extraction. Results: The mathematical modeling of RDC shows good agreement with the plant data with an accuracy of 95% and the model was used to investigate the effect of adding a co-solvent. Conclusion: Results show that by using furfural with added 2,2,4 trimethylpentane it is possible to perform the extraction process at a lower process temperature, 363.15K, compared with 393.15K using furfural as solvent, and also at a lower 1.3 solvent/feed ratio, compared with 1.5 when furfural alone was used for as the solvent. This process modification leads to saving of 38% of the consumed energy per cubic meter of product in the extraction process. © 2012 Society of Chemical Industry.
Publication Date: 2013
Korean Journal of Chemical Engineering (19757220)30(6)pp. 1201-1206
Drying kinetics of quince (Cydonia oblonga) in mashed form was investigated in a pilot scale freeze dryer. Experiments were conducted in various operating conditions, and the effects of initial moisture content, heat load power and the initiation time of heat application were investigated on drying rate and performance of the dryer. The experimental data of the moisture changes were correlated through non-linear regression and an appropriate mathematical model was obtained. The drying kinetics of the sample was determined on the basis of the pre-identified mathematical models as a function of operating parameters. The obtained values of mean relative percent deviation for the kinetics models of the primary and secondary drying stages are 7.47% and 5.94%, respectively. It is revealed that by applying a high heat load power at the beginning of the process the drying time is reduced significantly. © 2013 Korean Institute of Chemical Engineers, Seoul, Korea.
Publication Date: 2013
International Journal of Refrigeration (01407007)36(4)pp. 1233-1242
Exergy analysis was applied to investigate the performance of a domestic refrigerator originally manufactured to use 145 g of R134a. It was found that the highest exergy destruction occurred in the compressor followed by the condenser, capillary tube, evaporator, and superheating coil. Taguchi method was applied to design experiments to minimize exergy destruction while using R600a. Taguchi parameters were selected by the obtained results from R134a and an experiment using 60 g of R600a, which indicated similar results as R134a. Based on the outcomes, R600a charge amount, condenser fan rotational velocity and compressor coefficient of performance were selected for the design. The analysis of variance results indicated that R600a charge amount was the most effective parameter. At the optimum condition, the amount of charge required for R600a was 50 g, 66% lower than R134a one, which not only brings economic advantages, but also significantly reduces the risk of flammability of the hydrocarbon refrigerant. © 2013 Elsevier Ltd and IIR. All rights reserved.
Publication Date: 2013
Chemical Engineering and Technology (09307516)36(3)pp. 500-506
A semi-empirical kinetic correlation was obtained through a shrinking core model assumption for reactive absorption of CO2 with NaOH solution by applying response surface method analogy in a laboratory-scale spray-dryer absorber. The effect of approach temperature, absorbent concentration, nozzle diameter, and L/G ratio on the kinetic coefficient was studied and the optimum operating conditions to reach the maximum absorption were determined. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Mohammadi-moghadam, F.,
Amin, M.M.,
Khiadani, M.,
Momenbek, F.,
Nourmoradi, H.,
Hatamipour, M.S. Publication Date: 2013
Journal Of Environmental And Public Health (16879805)2013
The aim of this paper is to investigate the removal of toluene from gaseous solution through Glycyrrhiza glabra root (GGR) as a waste material. The batch adsorption experiments were conducted at various conditions including contact time, adsorbate concentration, humidity, and temperature. The adsorption capacity was increased by raising the sorbent humidity up to 50 percent. The adsorption of toluene was also increased over contact time by 12 h when the sorbent was saturated. The pseudo-second-order kinetic model and Freundlich model fitted the adsorption data better than other kinetic and isotherm models, respectively. The Dubinin-Radushkevich (D-R) isotherm also showed that the sorption by GGR was physical in nature. The results of the thermodynamic analysis illustrated that the adsorption process is exothermic. GGR as a novel adsorbent has not previously been used for the adsorption of pollutants. © 2013 Fazel Mohammadi-Moghadam et al.
Publication Date: 2012
Measurement: Journal of the International Measurement Confederation (02632241)45(7)pp. 1807-1813
This article presents an experimental investigation of substituting R134a with R436A (a mixture of R290 and R600a with a mass ratio of 56/44) in a 238 L single evaporator domestic refrigerator without any modification in refrigeration cycle. The refrigerator's compressor was charged with different amount of R436A, and in addition to refrigerator's power consumption during operation, the temperatures in different sections of the refrigerator were measured. Results showed that in comparison to the base refrigerator working with R134a, the ON time ratio and the energy consumption per day were reduced by 13% and 5.3%, respectively. Although the original R134a charge for this refrigerator was 105 g, the optimum charge for R436A was reduced to 55 g that exhibits 48% reduction in refrigerant charge. Also replacing R134a charge with R436A raised the energy efficiency index of the refrigerator from label "E" to label "D" according to Iranian National Standard No. 4853-2. © 2012 Published by Elsevier Ltd. All rights reserved.
Publication Date: 2012
Drying Technology (15322300)30(6)pp. 574-582
The wall deposition phenomenon in a pilot-scale spray dryer was investigated based on mathematical modeling and experimental trials. For this purpose, the governing equations were obtained and solved numerically by applying a mathematical modeling technique and an open-source computational fluid dynamics (CFD) software. The wall deposition, velocity distribution of the existing phases, and droplet trajectory in the drying chamber were determined. The effect of the operating parameters including the feed flow rate, inlet concentration of dissolved solid, and initial droplet diameter on the air flow pattern, droplet trajectory, and wall deposition was investigated. Through the experiments, the wall deposition of powder product in different positions of the drying chamber was measured. In modeling part of this study, we attempted to determine the effect of particle diameter on the percentage of wall deposition and the position where it occurred.The model results obtained for wall deposition were compared with collected experimental data and good agreement was observed. © 2012 Copyright Taylor and Francis Group, LLC.
Publication Date: 2012
Computers and Chemical Engineering (00981354)38pp. 44-51
A mathematical model is developed for simulation of dynamic behavior of coke-burning process in a hydrocracker reactor with an array of 4 fixed beds. The model is used for parametric study of the coke burning process. Results show that the effective parameters are inlet oxygen concentration, the flow rate of carrier gas and temperature within the beds. The effect of referred parameters on performance of regeneration of an industrial hydrocracker reactor is investigated for a real case and the optimum values of operating conditions are predicted. The optimum value for oxygen concentration during regeneration obtained as 0.85. mol%, with a predicted regeneration time of around 76. h. © 2011 Elsevier Ltd.
Publication Date: 2012
Drying Technology (15322300)30(2)pp. 128-137
In this study, green pea drying is investigated experimentally in a laboratory-scale spouted bed dryer. A mathematical model is also developed to investigate the effect of operating conditions on the performance of the system. The effect of operating parameters such as inlet air temperature, particle size, and flow rate of the drying air on the performance of the dryer are studied experimentally. In order to build the process model, it is necessary to analyze the transport in both solid and gas phases. A complete set of equations with no adjustable parameters is derived for existing zones in the spouted bed dryer in order to predict variations in the temperature and moisture content of the solid and gas phases with time for batch drying conditions. Model results are compared with corresponding experimental data. Agreement between the model results and experimental data is good. © 2012 Copyright Taylor and Francis Group, LLC.
Publication Date: 2011
Drying Technology (15322300)29(14)pp. 1648-1655
In this study, a drying kinetics model for predicting the drying of green pea particles using a bench-scale spouted bed with heat carriers is investigated. The experiments were carried out under different operating conditions. The effect of inert particle diameter, inert particle type, and the mass ratio of inert particles to green peas was examined based on the performance of the dryer and the rate of drying. As expected, the rate of drying increased with increased mass ratio of inert particles to green peas and thermal diffusivity of inert particles. © 2011 Taylor & Francis Group, LLC.
Publication Date: 2011
Separation and Purification Technology (1383-5866)80(3)pp. 509-518
In present study, a non-isothermal comprehensive mathematical model is developed for performance analysis of a spouted bed reactor in which CO 2 is removed by using a semi-dry chemical absorption process. For this aim, based on the hydrodynamic model of streamtube and equations of mass and energy balances for a reactive absorption process, the governing equations for gas and solid phases in three different regions of the bed are derived and solved numerically. The effects of variation of different operating parameters and process conditions are investigated and corresponding maximum, minimum and average values of errors are obtained by comparison of the model results with existing experimental ones. Results show that the superficial gas velocity and the approach to saturation temperature have considerable effects on CO 2 removal efficiency, while Ca/C molar ratio, inlet concentration of CO2 and static bed height of reactor do not influence performance of the reactor significantly. © 2011 Elsevier B.V. All rights reserved.
