Feed Temperature Research Articles

Novel bentonite modified PVDF membrane for desalination of synthetic-produced water by vacuum membrane distillation

ABSTRACT Membrane distillation (MD) has emerged as a highly promising method for the treatment of intricate and heavily contaminated water sources, such as those containing oily wastewater. The present study endeavors to advance the field by designing and evaluating a novel nanocomposite membrane comprised polyvinylidene fluoride (PVDF) and Bentonite (BNT) for application in vacuum membrane distillation (VMD) processes targeted at treating oily wastewater. A series of five nanocomposite flat sheet membranes were meticulously fabricated, incorporating varying quantities of bentonite (ranging from 0 to 0.8 g). Systematic characterizations were meticulously undertaken to comprehensively elucidate the influence of BNT incorporation on the structural and functional attributes of the developed membranes. These encompassed an array of analytical techniques, including Fourier Transform Infrared Spectroscopy (FTIR), atomic Force Microscopy (AFM), X-Ray diffraction (XRD), field emission scanning electron microscopy (FESEM), contact angle measurements (CA), as well as assessments of membrane thickness, porosity, pore size, and pore size distribution. The findings distinctly showcased the successful integration of BNT within the PVDF matrix, which correspondingly led to discernable augmentations in membrane surface roughness, hydrophobicity, and porosity. Employing consistent operational conditions involving a feed temperature of 50°C, a vacuum pressure of 30 kPa, and a NaCl solution with a concentration of 14.75 g/L, VMD experiments were systematically conducted. The empirical outcomes revealed that the incorporation of BNT notably conferred substantial enhancements upon the nanocomposite membrane’s performance. The pinnacle achievement was evidenced in a flux rate of 34 L/m2.h and a remarkable NaCl rejection rate of 99.92%, a result achieved by the nanocomposite membrane incorporating the highest content of BNT additives.

The effect of pretreatment and the operating temperature on reverse osmosis in make-up water preparation

Raw water cannot be used directly to compensate for water losses in power plants. Thus, a series of technological steps are required to produce ultra-pure water from fresh- or seawater. This study recommends using a proper pretreatment consisting of two-steps of microfiltration, ultrafiltration and nanofiltration. Desalination was carried out using two stages of reverse osmosis. The effect of increasing feed temperature from 25 °C to 48 °C on the second stage of reverse osmosis was studied and showed an exponential increase in flux and permeability, and reduced operation time. For freshwater, no temperature effect was observed on rejection in this temperature range; however, the highest rejection values calculated based on conductivity were observed at a 40 % recovery at all temperatures in seawater (96.6 % and 97.6 % at 48 and 25 °C, respectively). As a result of the multiparameter evaluation using the ranking method for the second reverse osmosis stage, 36 °C is found to be the optimum temperature.

Model Based Optimization of Energy Consumption in Milk Evaporators

This work explores five falling film evaporator (FFE) simulation approaches combined with energy consumption minimization strategies, namely Mechanical Vapor Recompression and Thermal Vapor Recompression (MVR and TVR, respectively). Global system analysis and advanced dynamic optimization strategies are then investigated to minimize steam consumption, the cost of steam, and the total annualized cost and to maximize product yield. The results indicate that higher TVR discharge pressures, or MVR compression ratios, along with higher feed temperatures, enhance evaporation but increase operational costs. The most economical option includes three evaporator effects with TVR to achieve 50% product dry mass content. However, for a 35% dry mass content, MVR becomes cost-effective with an 11% reduction in unit electricity prices or a simultaneous 7% drop in electricity prices and a 5% increase in gas-based steam prices. Furthermore, switching from milk powder production to milk concentrates leads to an annual cost reduction ranging from 10.8 to 44%. Additionally, a forecasted 20% (or more) reduction in biomass-based steam cost can lead to lower annual expenditure compared with the nominal NG-based steam case. Regarding the total annualized cost, for a new plant design, optimization strategies lead to a 9–45% reduction in the total cost depending on the case under consideration.

Identification of thermodynamic coupling phenomena and its relevance on flux coupling in pervaporation for bio-refining butanol from multicomponent Acetone-Butanol-Ethanol (ABE) mixtures

A comprehensive investigation of sorption characteristics and the influence of thermodynamic coupling on targeted organophilic pervaporation of bio-butanol from multicomponent Acetone-Butanol-Ethanol (ABE) fermentation solutions is presented, emphasizing the effect of penetrant-penetrant and penetrant-membrane interactions on sorption and permeation. In addition to initial screening of thermodynamic models and simulation of activity coefficients and volume fractions, pervaporation experiments were also analogously conducted for multicomponent ABE feed mixtures. Statistically validated second order models were then derived to forecast the influence of solvent concentrations, feed temperature and mutual interaction terms on butanol volume fractions and partial fluxes. Negative first order coupling effects due to ethanol and acetone are observed to be more significant for both activity coefficients and volume fractions, with sorption being most inhibited when acetone and ethanol are at their highest concentrations in feed. In contrast, contribution of non-linear and second order coupling effects is dominant in flux coupling, with positive “drag effects” due to additional plasticization being less pronounced at higher solvent concentrations. For instance, at 313.15 K, increasing ethanol and acetone concentrations by 3 wt% and 6 wt%, respectively, predicts reduction in volume fractions by approximately 29 % and 43 % compared to 3 wt% butanol-water binary systems. Conversely, the corresponding flux values exhibit initial increase of approximately 17 %, followed by subsequent decrease of around 14 %. However, sorption isotherms indicate that the penetrant-polymer interactions have a negligible influence on butanol volume fractions in the PDMS membrane irrespective of feed composition. Similarly, analysis of flux isotherms also suggests that flux coupling effects may ultimately be traced to thermodynamic coupling phenomena. Consequently, prudent membrane selection for pervaporation becomes crucial to overcome the inherently detrimental thermodynamic coupling effects and improve butanol recovery.

Theoretical and experimental investigation of cylindrical air gap membrane distillation system and effect of the membrane support net on its performance.

In present study a cylindrical module is studied based on air gap membrane distillation configuration and studied for desalination purpose. A complete theoretical model was developed with consideration of design and operating parameters that enabled a Cylindrical Air Gap Membrane Distillation (CAGMD) module specific performance analysis. Theoretical model was verified with the literature as well as with the experimental results carried out on a lab scale CAGMD module. The effect of support nets which supports the membrane on the air gap side is also discussed on the performance. Support nets made up of four different thermal conductivities material- copper, aluminum, brass and polypropylene (PP) are considered for this study. The effect of feed temperature and flow rate, air gap width, cold flow rate, effect of thermal conductivities of support nets and height of the module was studied on the performance of CAGMD module. Permeate flux, Specific Thermal Energy Consumption (STEC) and the Gained output ratio (GOR) was selected as the performance indicators and the results for all the resulted parameters obtained from experimental and theoretical model falls in good agreement with only 6% deviation, that suggests that the proposed model is best suitable for predicting the behavior of any cylindrical AGMD module with great effectiveness. It is suggested that for better performance of the system feed flow rate, temperature and cold flow rate should be maintained at higher level. Maximum permeate flux achieved from the CAGMD module is 9.22kg/m2h.

Process simulation of methanol production via carbon dioxide hydrogenation

The performance of a packed bed reactor for CO2 conversion to methanol was investigated. Because of the exothermic reaction, temperature and concentration gradients happen along the reactor. A 2D packed-bed reactor model was applied for numerical investigations, coupled with detailed reaction kinetics and transport phenomena. The effect of feed inlet pressure and temperature on CO2 conversion and temperature profiles along the reactor was evaluated. The results showed that firstly increase in the temperature in the reactor because of the presence of exothermic reactions and then slight decrease in the temperature at top section of the reactor. Pressure was decrease from 55 bar to around 54 bar along the reactor. It was found that the CO2 conversion at outlet of reactor was 18.18 % at T = 475 K and it was increased to 23 % at temperature of 498 K and 555 K. The CO2 conversion was reached its maximum at short distance from the reactor entrance at T = 555 K. Also, the outlet temperature of gas mixture was increased from 522.53 K to 534.56 K with increasing feed inlet pressure from 35 bar to 55 bar. The CO2 conversion was 18.12 %, 20.77 %, and 22.96 % at pressures equal to 35, 45, and 55 bar respectively.

Engineering Multinanochannel Polymer-Intercalated Graphene Oxide Membrane for Strict Volatile Sieving in Membrane Distillation.

Graphene oxide (GO) membranes enabled by subnanosized diffusion channels are promising to separate small species in membrane distillation (MD). However, the challenge of effectively excluding small volatiles in MD persists due to the severe swelling and subsequent increase in GO interlamination spacing upon direct contact with the hot feed. To address this issue, we implemented a design in which a polymer is confined between the GO interlaminations, creating predominantly 2D nanochannels centered around 0.57 nm with an average membrane pore size of 0.30 nm. Compared to the virginal GO membrane, the polymer-intercalated GO membrane exhibits superior antiswelling performance, particularly at a high feed temperature of 60 °C. Remarkably, the modified membrane exhibited a high flux of approximately 52 L m-2 h-1 and rejection rates of about 100% for small ions and 98% for volatile phenol, with a temperature difference of 40 °C. Molecular dynamics simulations suggest that the sieving mechanisms for ions and volatiles are facilitated by the narrowed nanochannels within the polymer network situated between the 2D nanochannels of GO interlaminations. Concurrently, the unrestricted permeation of water molecules through the multinanochannel GO membrane encourages high-flux desalination of complex hypersaline wastewater.

Process optimization of osmotic membrane distillation for the extraction of valuable resources from water streams

The rising demand for sustainable wastewater management and high-value resource recovery is pressing industries involved in, e.g., textiles, metals, and food production, to adopt energy-efficient and flexible liquid separation methods. The current techniques often fall short in achieving zero liquid discharge and enhancing socio-economic growth sustainably. Osmotic membrane distillation (OMD) has emerged as a low-temperature separation process designed to concentrate valuable elements and substances in dilute feed streams. The efficacy of OMD hinges on the solvent’s migration from the feed to the draw stream through a hydrophobic membrane, driven by the vapor pressure difference induced by both temperature and concentration gradients. However, the intricate interplay of heat and mass processes steering this mechanism is not yet fully comprehended or accurately modeled. In this research, we conducted a combined theoretical and experimental study to explore the capabilities and thermodynamic limitations of OMD. Under diverse operating conditions, the experimental campaign aimed to corroborate our theoretical assertions. We derived a novel equation to govern water flux based on foundational principles and introduced a streamlined version for more straightforward application. Our findings spotlight complex transport-limiting and self-adjusting mechanisms linked with temperature and concentration polarization phenomena. Compared with traditional methods like membrane distillation and osmotic dilution, which are driven by solely temperature or concentration gradients, OMD may provide improved and flexible performance in target applications. For instance, we show that OMD—if properly optimized—can achieve water vapor fluxes 50% higher than osmotic dilution. Notably, OMD operation at reduced feed temperatures can lead to energy savings ranging between 5 and 95%, owing to the use of highly concentrated draw solutions. This study underscores the potential of OMD in real-world applications, such as concentrating lithium in wastewater streams. By enhancing our fundamental understanding of OMD’s potential and constraints, we aim to broaden its adoption as a pivotal liquid separation tool, with focus on sustainable resource recovery.

Experimental Investigation of Vacuum Membrane Distillation (VMD) Performance Based on Operational Parameters for Clean Water Production

Freshwater shortage is an ongoing concern across the world, due to increasing populations and climate change. Vacuum membrane distillation (VMD) is a viable approach for producing fresh water to meet the needs of society. In the current study, an experimental investigation has been conducted on a laboratory-scale single-stage module to explore the impact of operational parameters such as feed temperature, vacuum pressure, and feed salinity on the performance of vacuum membrane distillation (VMD), including permeate flux, gained output ratio, and specific thermal energy consumption. Results show that increasing the feed temperature and feed flow rate, and reducing the salinity, increases the permeate flux. As the feed temperature rises from 60 to 70°C, the permeate flux increases from 1.90 to 4.36 kg/m²h at a permeate pressure of 12 kPa and salinity of 30 g/L. Similarly, increasing the vacuum pressure from 12 to 18 kPa reduces the permeate flux. As a result, the specific thermal energy consumption increases from 728 to 803 kWh/m³. From experimental findings, it was observed that the rejected brine from VMD retains sufficient energy that could be utilized in another desalination system.

Performance assessment of a modified air-gap and water-gap membrane distillation systems

This work experimentally evaluates and compares the performance of four membrane distillation (MD) units with and without an internal gap rotating impeller blade. The novelty of the current study lies in the installed impeller within the condensation cavity and the impeller design parameters. The investigated MD units include a novel modified water-gap MD (M-WGMD) system featuring an internal impeller blade; a novel modified air-gap MD (M-AGMD) system with an internally rotating impeller blade; a regular water-gap MD (WGMD) process; and a conventional air-gap MD (AGMD) system. The evaluated system performance index includes gained output ratio (GOR) and vapor flux. The performance of the four MD systems is assessed and compared against each other under the same test conditions for various system design and operating variables, including impeller blade material, impeller blade angle, saline feed temperature, coolant temperature, and saline feed flowrate. Findings indicate that M-WGMD and WGMD systems (modified and conventional) produce higher flux than M-AGMD and AGMD units. Meanwhile, air-gap MD units (AGMD and M-AGMD) exhibits better energy efficient (higher GOR) than WGMD and M-WGMD systems. Furthermore, modified MD systems recorded superior performance compared to conventional MD systems and the blade angle effect is more influential than the blade material. At 80 °C feed temperature and 3200 mg/L feed salinity, the M-WGMD reaches a maximum flux of 128.39 kg/m2h and a GOR of 0.7702. On the other hand, the WGMD attained a flux of 67.32 kg/m2h and a GOR of 0.6199. The M-AGMD recorded a flux of 30.20 kg/m2h and a GOR of 0.8696. For the AGMD system, the GOR and the flux values are 0.7357 and 15.58 kg/m2h, respectively.

Membrane distillation of saline feeds and produced water: A comparative study of an air-gap and vacuum-driven modules

Air gap membrane distillation (AGMD) and vacuum membrane distillation (VMD) are two membrane-based desalination processes that utilize temperature differences to generate water vapor for purification. This study evaluated the viability of both processes for treating different types of saline water, such as Arabian Gulf seawater and oil field-produced water. Factors such as feed temperature, feed concentration, recirculation flow rate, air gap, and vacuum space depth were investigated to understand their impact on permeate flux in AGMD and VMD configurations. The results showed that AGMD achieved higher permeate flux at lower feed concentrations, while VMD performed better at higher concentrations. Increasing the feed temperature led to increased permeate flux in both configurations, with AGMD showing a greater increase. Results also indicated that lower gaps were preferred in both configurations, and the tested membranes showcased excellent salt rejection capabilities. These findings provide valuable insights into the potential applications of AGMD and VMD in desalination, especially in regions with water scarcity or pollution.

Design and two step process optimization of a reactive distillation column for improving production amount of ethyl acetate and water

In this study, two step optimization was performed for operating conditions of a reactive distillation (RD) column using simulation outputs. The effects of the operating parameters of the RD column, on the ethyl acetate (EtAc) amount as a result of the reaction between ethanol (EtOH) and acetic acid (HAc) were assessed. The response surface methodology (RSM) was applied to determine the optimum operating conditions for the RD column. The two step experimental design used in RSM was created with the Design Expert (DE) program. The Plackett-Burman (PB) design was used to determine the most important parameters affecting on the designed RD column for production of EtAc amount. The most important parameters were determined as HAc feed rate (kmol/h), EtOH feed rate (kmol/h), reflux ratio and temperature (°C). After PB design Central Composite Design (CCD) was applied to determine the optimum operating conditions of these most important parameters for the RD column. ANOVA was used to investigate the interaction between the response and independent variables with the obtained data and 3 dimensional (3D) plots created by the program were interpreted. A second order regression model according to the independent variables for the EtAc amount (response) was developed with DE program. The optimum operating conditions for the designed RD column were obtained as HAc feed rate 149.86 kmol/h, EtOH feed rate 99.99 kmol/h, feed temperature 70 °C and reflux ratio 2.50. The production of EtAc amount which determined with model coefficients and recommended by the program were compared and relative errors between the model results and the predicted values were less than 1%. The obtained results were showed that RSM may be a suitable method for optimization of operating parameters in RD columns.

Numerical model of vapor-air-diesel autothermal reformer

The use of fuel cell power plants is a promising area in the generation of electricity. The path to their widespread use is hindered by their high cost and the availability of the fuel used. To solve this problem, effective energy conversion systems operating on diesel fuel are being developed. The main goal is to create a device (a fuel processor), which would convert diesel fuel into a hydrogen-containing gas. The device consists of several components: a nozzle for injecting liquid fuel having the form of drops into superheated steam, a mixing and vaporization zone for diesel fuel, an air supply area, and a reaction zone including a catalyst. The selection of temperature for the vaporization process should be made in such a way that, on the one hand, liquid droplets do not come into contact with the catalyst surface, and, on the other hand, gas-phase reactions are not initiated in the mixing zone. Developing such a device requires not only conducting laboratory experiments and studying the process catalyst, but also optimizing the basic physical parameters of the device. These parameters are its linear dimensions, operational temperature, reactant flow rates, and many others. Carrying out such a study is impossible without using methods of mathematical modeling. This significantly reduces the time and cost of work. This paper presents a digital model of an air-hydrocarbon mixture generator in an axisymmetric formulation. The dynamics of subsonic multiphase flow of water vapor carrying drops of liquid diesel fuel, the process of diesel fuel evaporation and mixing with water vapor and air are studied. The mathematical model is implemented in the ANSYS Fluent package (academic license of SSCC SBRAS). A series of calculations for various mixture feed temperatures are performed to optimize the main parameters. For the established optimal temperature, modeling of the mixture mixing process with air is carried out.

Poly(vinyl alcohol)/ZSM-5 zeolite mixed matrix membranes for pervaporation dehydration of ethanol and n-propanol.

In this study, mixed matrix membranes (MMMs) composed of poly(vinyl alcohol) (PVA) and porous ZSM-5 zeolite are thoroughly investigated for concentrating alcohols of ethanol and n-propanol via dewatering pervaporation. The effects of the zeolite content (10-30 wt.%), feed composition (5-30 wt.% water), and feed temperature (50-90 °C) on the pervaporation flux/separation factor and component permeance/selectivity of these MMMs are examined in detail. These MMMs achieve higher separation efficiency and pervaporation flux than their pure PVA counterparts as expected, even if the dehydration results strongly depend on the pervaporation conditions. The disparity in pervaporation performances acquired for different alcohol solutions may be understood in terms of polarity and molecular size, which differ among these alcohol molecules. The PVA/zeolite MMM of 20 wt.% ZSM-5 zeolite content performs substantially stably at 60 °C for the feed with 80 wt.% alcohol while maintaining separation factors of 660 or 820 and total fluxes of 970 or 825 g/m2h for dewatering water/ethanol and water/n-propanol, respectively. Thus, our membranes appear to be technically feasible for practical alcohol dehydration uses.

Treatment of Antihypertensive and Cardiovascular Drugs in Supercritical Water: An Experimental and Modeled Approach

Pharmaceutical pollutants are considered emerging contaminants, representing a significant concern to the ecosystem. Thus, this study reports on the degradation of antihypertensive and cardiovascular drugs (atenolol, captopril, propranolol hydrochloride, diosmin, hesperidin, losartan potassium, hydrochlorothiazide, and trimetazidine) present in simulated wastewater through applying the technology of oxidation using supercritical water (SCW). The operational parameters of the treatment process, particularly the feed flow rate, temperature, and concentration of H2O2, were assessed. A central composite design of experiments associated with differential evolution was employed in the optimization. Both liquid and gaseous phase products were submitted to physical–chemical characterization. As a result, the optimized conditions for the treatment were discovered to be a feed flow rate of 13.3 mL/min, a temperature of 600 °C, and a H2O2 oxidation coefficient of 0.65, corresponding to the oxygen stoichiometric coefficient in the carbon oxidation chemical reaction. Under optimal conditions, the total organic carbon (TOC) decreased from 332 to 25 mg/L (92.1%), and the pharmaceutical molecules underwent near-complete degradation. The physical–chemical parameters also met with the main environmental regulations for wastewater disposal. The compounds determined in the gaseous phase were CO2 (97.9%), H2 (1.3%), CH4 (0.3%), and CO (0.5%.). Additionally, a modeling thermodynamic equilibrium of the system was performed, based on the experimental data. The results revealed that SCW technology has a great potential to oxidize/degrade organic matter and can be applied to treat pharmaceutical pollutants.

Unfavorable process intensification of double column reactive extractive distillation system

This study evaluated the energy saving potential of process intensified double column reactive extractive distillation (DC-RED) through three case studies. The results showed that process intensified technologies, thermally coupled reactive extractive distillation (TC-RED) and dividing wall reactive extractive distillation (DW-RED), did not yield any energy savings compared to conventional DC-RED. Contrary to the expectation, the elimination of the remixing effect in the process intensified DC-RED did not lead to any energy savings. Further analysis revealed that the remixing effect was not significant enough to achieve energy savings through process intensification, and the strong reaction exotherm in DC-RED reduced the potential for energy saving. Additionally, the higher interconnection flowrate in TC-RED and DW-RED resulted in higher energy consumption due to the increased boil-up ratio. Moreover, the lower feed temperature to the solvent recovery column (SRC) led to less energy efficiency and larger reboiler duty. An alternative energy saving scheme was proposed by adding a heat exchanger (HEX). The addition of HEX led to energy savings of 37.23 % in Acetonitrile (ACN)/Isopropanol (IPA)/Water separation, 45.62 % in Ethyl Acetate (EA)/Ethanol (EtOH)/Water separation, and 39.21 % in IPA/EA/Water separation.

Bis(triethoxysilyl)ethane (BTESE)-Organosilica Membranes for H2O/DMF Separation in Reverse Osmosis (RO): Evaluation and Correlation of Subnanopores via Nanopermporometry (NPP), Modified Gas Translation (mGT) and RO Performance.

A 40 cm length Bis(triethoxysilyl)ethane (BTESE) membrane having different pore sizes was successfully prepared by changing the number of coating times for gas permeation (GP) and organic solvent reverse osmosis (OSRO) separation study. It was found that BTESE-6 membranes prepared through six-time coating consisted of small-sized pores in the range 0.56 to 0.64 nm estimated using modified Gas Translation (mGT) method and 0.59 to 0.67 nm estimated by nanopermporometry (NPP) method, respectively. These membranes demonstrated a high DMF rejection, RDMF > 95% with total flux, Jv total > 5 kg m-2 h-1 at operating condition feed pressure, Pf: 8 MPa; feed temperature, Tf : 50 °C; and feed flowrate, Qf : 30 mL/min; and they exhibited a high degree selectivity of He/SF6 in the range of ~ 260-3400 at a permeation temperature 200 °C. On the other hand, the larger pore sizes of the BTESE-4 membranes (pore size estimates > 0.76 nm to 1.02 nm) exhibited low DMF rejection and a low degree selectivity of He/SF6 around ~30% and 25, respectively, at the same operating condition as BTESE-6. Both GT and NPP methods can be considered as an indicator of the measurement membrane pore size. From this study, it was found that He and SF6 gases can be some of the potential predictors for water and DMF permeance. Furthermore, by comparing our OSRO membrane with other PV membranes for DMF/H2O separation, our BTESE-6 membranes still exhibited high flux in the range of 3-6 kg m-2 h-1 with a separation factor H2O/DMF in the range of 80-120.

Production of Light Naphtha by Flash Distillation of Crude Oil

The escalating global demand for sustainable, renewable energy sources has catalyzed research into advanced refining processes, particularly focusing on the generation of essential raw materials like light naphtha. This paper delves into the production of light naphtha via the flash distillation of crude oil, underlining its critical role in fulfilling the petrochemical industry's requirements. The research delineates the fundamentals of flash distillation, incorporating both physical and mathematical models, with a specific emphasis on Raoult's Law, to demystify the hydrocarbon separation process in crude oil. The mathematical framework encompasses material and energy balances, coupled with the application of liquid-vapor equilibrium equations, thereby shedding light on the thermodynamic principles steering this procedure. The progression of this study involved analyzing the distillation curve of the referenced crude oil and identifying the pseudo-components representative of the involved hydrocarbons. Utilizing the DWSIM commercial simulator, the flash distillation process of Nemba crude oil was simulated, taking into account diverse operational conditions and thermodynamic models. The outcomes were juxtaposed with industrial datasets, demonstrating a significant alignment and affirming the simulation's predictive efficacy. A parametric sensitivity analysis was conducted to refine light naphtha yield, elucidating the effect of variables like the temperature of crude oil feed and naphtha separator feed on the process efficiency. The response surface methodology underscored the feasibility of augmenting naphtha production under certain conditions. Furthermore, this study assessed the impacts of employing two distinct thermodynamic models – the Soave-Redlich-Kwong (SRK) and Peng-Robinson (PR) equations of state. This analysis revealed minimal discrepancies in physical parameters, confirming the simulation's robustness and the reliability of both models. The findings of this paper validate the efficacy of flash distillation in light naphtha production, with numerical simulation emerging as a potent tool for enhancing process optimization and predictive analysis. These insights not only contribute to a deeper understanding of environmental sustainability but also offer strategies for maximizing light naphtha production in the oil industry. In conclusion, the results from this investigation significantly advance our comprehension of phase equilibrium profiles and their relationship with the applied thermodynamic state equations, thereby enriching the quality of the results.

Seasonal dynamic modeling and simulation of solar thermal membrane desalination system for sustainable freshwater production: a case study of Tanta, Egypt

AbstractMembrane distillation (MD) is an effective process for desalinating seawater, combining the merits of both thermal and membrane distillation. In this context, the sizing methodologies and optimization strategies are developed from the balance of the system’s energy demand. Therefore, accurate numerical modeling of the heat transfer and thermodynamic behavior of the MD systems is crucial for the optimal design of solar-based MD systems. The interest in utilizing solar thermal heating techniques for feed water heating in MD systems is increasing worldwide for sustainable freshwater production and lowering energy consumption. Hence, in this research, a coupled analytical modeling based on heat transfer, mass transport, and thermodynamic analysis is created to dynamically simulate a solar direct contact membrane distillation system (SDCMDS) driven by vacuumed tubes solar collectors (VTSCs) to analyze its performance, under real weather of Tanta, Egypt. The influences of the solar collecting area on the performances of the proposed SDCMDS for augmenting the freshwater production of the SDCMDS are studied. Four cases of the proposed SDCMDS are investigated: two identical VTSCs of 1.80 m2 each unit in summer (Case I), two identical VTSCs in winter (Case II), four identical VTSCs in summer (Case III), and four identical VTSCs in winter (Case IV). The results show that the utilization of four VTSCs connected in series significantly improved the feed seawater temperature range from 30.0 to 70.5 °C compared to a feed temperature range of 30.0–49.5 was achievable by utilizing only two VTSCs. Moreover, the daily averaged permeate flux were 2.21, 1.29, 3.41, and 2.07 L/day per m2 of solar harvesting area with daily cumulative distilled water yield of 7.48, 4.60, 23.04, and 14.78 L/day for Cases I, II, III, and IV, respectively, at a saline flowrate of 0.20 kg/s. The daily average total efficiency of the SDCMDS was obtained to be 14.70%, 12.50%, 24.95%, and 22.50% for Cases I, II, III, and IV, respectively.

Modelling the flux decline induced by gypsum scaling in direct contact membrane distillation

Scaling has been a major technical challenge in the membrane distillation (MD) process, hindering the broader application of MD processes. Despite the increasing number of studies on MD scaling, there are limited prediction tools to describe the scaling process and help make informed decisions about the experimental conditions to prevent scaling and its irreversible damage. In this paper, a semi-analytical model was developed based on the classical nucleation theory and crystal growth to model the membrane area reduction caused by the deposition of inorganic salt crystals on the membrane surface, which is equivalent to the decrease in permeate flux resulting from scaling. The model was developed using calcium sulphate, a model scalant. The model was validated and verified with available literature data, and it has been proved that the model has the capability to produce reasonable predictions on the onset of flux decline and the declining rate with respect to the experimental data with the coefficient of determination (R2) ranging from 0.74 to 0.96. The sensitivity analysis was applied on the model, which revealed that flux decline would happen earlier in the case of higher feed temperature, higher feed velocity, and higher initial feed concentration.