Inlet Feed Research Articles

Numerical Investigation of Fabricated MWCNTs/Polystyrene Nanofibrous Membrane for DCMD.

The effect of compositing multiwalled carbon nanotubes (MWCNTs) with polystyrene (PS) to fabricate nanofibrous membrane by electrospinning technique and comparing the direct contact membrane distillation (DCMD) performance of the blank and composite membranes is evaluated numerically. Surface morphology of both the pristine and the composite membrane was studied by SEM imaging while the average fiber diameter and average pore size were measured using ImageJ software. Static water contact angle and porosities were also determined for both membranes. Results showed significant enhancement in both the hydrophobicity and porosity of the composite membrane by increasing the static water contact angle from 145.4° for the pristine PS membrane to 155° for the PS/MWCNTs composite membrane while the porosity was increased by 28%. Simulation results showed that at any given feed inlet temperature, the PS/MWCNTs membrane have higher permeate flux and better overall system performance.

Critical Quality Predictive Control of Fed-Batch Mammalian Cell Bioreactors

Abstract A model predictive control (MPC) formulation for a mammalian cell fed-batch bioreactor processes is developed. A nonlinear fundamental model for the bioreactor is used to generate a database of historical runs comprising of the measurement variables and the manipulated input feed flow rate to the bioreactor. The database is used with subspace identification methods to develop a state-space model of the process. The identified model is used to design various MPC formulations with different objective criteria, including the conventional trajectory-tracking objective function and a novel terminal objective for maximizing the product yield at completion of a run. Case studies involving the simulated bioreactor process demonstrate the efficacy of the MPC algorithms subject to unknown disturbances, random variations in the inlet feed glucose and glutamine concentrations, and measurement noise. Compared to the traditional proportional-integral control algorithm, the trajectory-tracking predictive control algorithm is able to better track the reference glucose concentration set-point with an improvement of 5.1% in the tracking error. The critical quality attribute predictive control algorithm designed to maximize the product yield results in a 3.9% increase in the product concentration at the completion of the run.

Experimental and theoretical optimization of an inclined type solar still using PV sustainable recirculation technique

Solar stills are very useful in coastal and semi-arid areas, where the water consumption is low, though there exist a need to enhance its distillate productivity to viable its usage in areas of high water consumption. In this proposed research, a sustainable recycling technique had been implemented to boost the distillate throughput of an existing commonly used inclined type solar still. The developed inclined categories of solar still attached with a PV recirculation pump have been experimented and tested at Tirunelveli district, India (8.71390 N, 77.75670E). In this research experimentation, the feed water is heated to higher temperature by means of solar still, the obtained distilled water at higher temperature have been recycled to heat the inlet feed water, thereby the inlet water getting pre heated and the outlet water getting cooled easily in shortest time. As the outcome of the research, the effectiveness of the distillation process enhanced and more water can be collected from the solar still. As the result of the experimentations, it has been found that the black cotton cloths are having more diffusion effect and achieves a maximum productivity of 3.61 L/day. Recycling the hot water due to solar energy exhausted from the designed inclined solar still have been done with the PV recirculation pump, thereby the efficiency and productivity of the developed solar thermal desalination system have been enhanced to produce 4.43L/day.

Optimization of Spray Drying Conditions for Developing Nondairy Based Probiotic Sohiong Fruit Powder

ABSTRACT The interest in nondairy-based probiotic foods has significantly increased due to lactose intolerance, casein allergy, and associated cholesterol risks. Fruit-based products could be an excellent alternative option. In the present work, Sohiong (Prunus nepalensis) juice has been used for the development of a possible probiotic product. Sohiong juice was enzymatically extracted and fermented with probiotic Lactobacillus plantarum subsp. plantarum. The fermented juice was then spray dried to make a probiotic powder. The spray-drying process conditions including maltodextrin concentration (12–25% w/w), inlet temperature (120–140°C), and inlet feed rate (120–240 ml/h) were optimized using response surface methodology. The responses evaluated were drying yield, moisture content, encapsulation efficiency, and color difference. The results showed that the optimum conditions for the production of Sohiong juice powder with acceptable quality were 120°C inlet temperature, 12% w/w maltodextrin concentration, and 201 ml/h feed rate. A powder yield of 57.68% at a moisture content of 3.95% could be achieved with an encapsulation efficiency of 85.75%. The viable probiotic cell count in the Sohiong powder was more than the recommended value of 6.0 log CFU/g up to 36 days when stored at ambient condition and up to 104 days under refrigerated condition suggesting the feasibility of developing spray-dried nondairy probiotic powder from Sohiong juice.

An integrated approach to enhance the desalination process: coupling reverse osmosis process with microbial desalination cells in the UAE

Abstract The growing need for better sources of fresh water has led to water desalination to become a dominant technology in the water industry, especially in arid countries like the UAE. Across the globe, reverse osmosis (RO) has become the key method used to desalinate seawater. Due to the high energy requirements of RO desalination, the need to reduce the energy load has become a pertinent area of research. Microbial desalination cells (MDCs) are an emergent technology that show great promise when integrated into the RO desalination process. Studies have shown that a significant proportion of the energy utilized in RO desalination could be eliminated by using MDCs as a pretreatment process. In this study, the integration of various MDC types into the pretreatment process for RO desalination were compared and explored. Existing MDC integration setups were briefly explained. Research was split into possible configurations for the integration. This includes optimization of key parameters such as anodic inoculum, feed inlet ratios and accompanying pretreatment processes. The limitations and challenges faced in the integration were investigated and the required future studies aligned with subject was deliberated.

Volumetric heat transfer coefficient in spray drying of soymilk powder

In this study, an empirical equation of the volumetric heat transfer coefficient in spray-drying of soymilk powders was developed. Response Surface Methodology RSM was employed to examine the effects of feed concentration and inlet air temperature on the volumetric heat transfer coefficient in the drying chamber. Overall, results show that the concentration of feed solution had a greater effect than the inlet air temperature. An increase in the feed concentration led to a sharp decrease in the volumetric heat transfer coefficient in the drying chamber, whereas the volumetric heat transfer coefficient increased slightly with rising the inlet air temperature of spray dryer. Highlights Volumetric heat transfer coefficient of spray dryer was compared to other dryers. Empirical equation of the volumetric heat transfer coefficient was developed. Response Surface has been a relevant methodology to examine the spray drying conditions Concentration of feed solution had a greater effect than the inlet air temperature.

Interferometric analysis of flow around a horizontal tube falling film evaporator for MED systems

In this work, an optical shadow method (non-intrusive) was used to evaluate the falling film thickness around the circumference of a horizontal tube. A Mach-Zehnder Interferometer was used to visualize the isotherm formation. Most of the well established non-intrusive techniques for measuring film thickness around the cylinder fails to measure the film thickness near to entry region (θ<30∘) and towards the exit region (θ>140∘) because of the limitation and complexity of the apparatus. Relavance of this work lies on the simplicity of the measurement and the range of circumferential angles that can be investigated (10∘≤θ≤170∘). This technique involves image visualization, thus, serves as a tool for analyzing the film both quantitatively and qualitatively. A lucid algorithm was developed for image processing along with a set of intensity profile tracking procedures making the whole process of film thickness measurement more obvious. The measured film thickness is showing good agreement with the commonly used empirical formula, and the effectiveness of using those empirical formulas for the small diameter tubes was analyzed. Further, this study was extended to determine the effects of flow rate and feed inlet temperature on film thickness. Film thickness variation around the circumference of the cylinder is showing an increase in trend with increasing Reynolds number, but a change in trend with the varying feed inlet temperature is found to be marginal. This study is further extended for different positions of the tube in the order of impingement of film or feed inlet as top, middle and bottom tubes and the film thickness variation was again found to be marginal. Dynamic characterization at θ=10∘ was studied and the maximum film thickness variation was found to be 11.8%. A standard error of mean analysis was performed on every data set which validates the reproducibility and the dynamic measurement capability of the technique used.

Hybrid of Adsorption and Nanofiltration Processes as a Capable Removal Method for HANs Removal

In the present study, treatment of Halostonitriles (HANs) contaminated water has been investigated. These materials are a new generation of disinfectant by-products (DBPs) that result from the halogenation of nitrogen by-products. Hybrid treatment method is one of the most effective methods with high performance efficiency for removal of contaminants such as HANs, which has been evaluated in this study. In the present study, performance of the adsorption process, ultrafiltration process (UF) and nano-filtration (NF) process have been investigated. In this regard, the thermodynamic changes of process, the adsorption of contaminants in a fixed bed and under continuous operating process, the rate of membrane permeability, the effect of flow rate, the effect of feed inlet concentration and finally complementary method as hybrid process were studied.

Numerical Modelling and Industrial Verification of Ethylene Dichloride Cracking Furnace

In this paper, the radiation section of ethylene dichloride (EDC) cracking furnace, considering the chemical reaction, was numerically modelled using computational fluid dynamics (CFD). This study investigated the influence of some parameters such as mass flow rate, the inlet temperature of fluid into the radiation section, and heat flux on the conversion and changes in velocity, pressure, and temperature of the fluid along the coil passes, as well as the outlet stream of the coil. Then, the modelling results were compared with a series of industrial data of an industrial EDC cracking furnace. The results showed that considering the variable heat flux boundary condition is more compatible with the industrial data rather than the constant heat flux boundary condition. Increasing the feed inlet temperature to the furnace, increased the EDC conversion due to the endothermic nature of the thermal cracking reaction. Furthermore, reducing the inlet mass flow rate led to a significant increase in the conversion, temperature, and mass fraction of the products due to an increase in residence time.

Effect of encapsulation agents on antioxidant activity and moisture content of spray dried powder from Mahkota Dewa fruit extract

Mahkota Dewa is rich in bioactive compounds including mangiferin, saponin and polyphenols. This work aims to investigate the encapsulation of Mahkota Dewa by spray drying using different types of encapsulation agent. A subcritical water extraction process was used to extract the bioactive compounds from dried Mahkota Dewa prior to spray drying process. The encapsulation agents used were maltodextrin (MT), arabic gum (AG) and mixture of arabic gum-maltodextrin (AG-MT). The spray drying conditions namely inlet dry air temperatures, dry air flow rate and inlet feed flowrate were 200°C, 3.7 m/s and 485 mL/h, respectively. The spray dried powder samples were evaluated for antioxidant activity and moisture content and compared with those without encapsulation agent. A high value of antioxidant activity and low moisture content were observed for samples with encapsulation agents. Result suggested the maltodextrin produced particles with the lowest moisture content (4.84 %) and highest antioxidant activity (94.22%), thus can be recommended as the most suitable encapsulation agent in this work.

Experimental investigation of the effect of the spacer and operating conditions on mass transfer in direct contact membrane distillation

This study examines the effect of spacers and operating conditions (feed inlet temperature, velocity, and feed concentration) on mass transfer characteristics in direct contact membrane distillation (DCMD) systems. The experimental results showed that velocity of the feed and permeate influenced the mass transfer properties more significantly than the temperature and concentration factors. Among the five investigated spacers, the plastic spacer (PL4) had the most influence on mass transfer characteristics, which was proven through analysing the mass transfer coefficient (ks), boundary layer thickness (δ), shear stress (τ) as well as flow property in DCMD spacer-filled channels. Moreover, the mass transfer correlation for each spacer and a general mass transfer correlation for all spacers were determined. Through comparisons between theoretical and experimental Sherwood numbers, the mass transfer correlation developed by Grober for empty channels could be used to describe the mass transfer characteristic in spacer-filled channels in this study.

Iron Contamination and Local Distribution within a 50 Cm Single-Channel Proton Exchange Membrane Water Electrolysis Cell

Proton exchange membrane water electrolysis (PEMWE) will play a major role in the clean and versatile energy conversion in the near future.[1] Offering scalable solutions of PEMWE are of high industrial interest and have to provide a sufficient durability and reliability.[2] To achieve this, a better understanding of the impact of contamination on the PEMWE performance is very crucial. In this context, the membrane electrode assembly (MEA) is susceptible to several degradation processes like metallic cations (Fe3+/2+ stemmed from tubing). In particular, soluble and reduced iron species forming by Fenton reaction might attack via radicals the MEA.[3,4] Hence, analyzing impurities and their resulting impacts on e.g. the proton transport resistance and degradation mechanisms at different length scales and local distributions are of large interest.In this work, the influence of spatially resolved iron contamination in MEAs on the cell performance has been investigated using a 50 cm single-channel PEMWE cell equipped with local current density measurement setup.[5] Adding defined amounts of FeSO4 via the anode inlet feed, the changes on the three main regimes of overpotentials, i.e. kinetic, ohmic and mass transport, is correlated with the current density mapping as well as local and global electrochemical impedance spectroscopy (EIS) measurements. Ex-situ scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) are used to detect the distribution and agglomeration of iron species within the MEA.With this combined approach of electrochemical and ex-situ physical methods, the contamination pathways and their effects of (spatially resolved) iron contamination on the overall performance of MEA are investigated as a function of degree of contamination and operating conditions. Especially, the (spatially resolved) overpotential-specific degradation processes along the 0.5 m channel, which mimic a technically relevant stack size, allow us to conclude on the optimum design of MEA, targeting use of mitigation strategies and development of accelerated stress test protocols.[1] M.A. Pellow, C.J.M. Emmott, C.J. Barnhart, S.M. Benson, Energy Environ. Sci. 8 (2015) 1938-1952.[2] P.K. Shen, C.-Y. Wang, S.P. Jiang, X. Sun, J. Zhang, Electrochemical Energy: Advanced Materials and Technologies, CRC Press, 2015.[3] X. Wang, L. Zhang, G. Li, G. Zhang, Z.-G. Shao, B. Yi, Electrochim. Acta 158(2015) 253-257.[4] C. Rozain, P. Millet, Electrochim. Acta 131 (2014) 160e167.[5] C. Immerz, B. Bensmann, P. Trinke, M. Suermann, R. Hanke-Rauschenbach, JECS 165 (16) (2018)

Evaluation of direct contact membrane distillation coupled with fractionation and ozonation for the treatment of textile effluent

Direct contact membrane distillation (DCMD) coupled with fractionation or ozonation as a pretreatment method was investigated for the treatment of combined textile effluent. The stand-alone DCMD process has difficulty in directly treating the effluent due to the wetting issue, in particular at higher feed temperatures. Fractionation was conducted to 21 L combined effluent for 24 h. After the pretreatment, total organic carbon (TOC) and conductivity decreased by 47 % and 28 %, respectively, but an additional 5% concentrate was also generated. A long-term DCMD experiment was conducted to treat the fractionated effluent for 50 h and a high water recovery of 98 % was achieved. The optimum recovery of 95 % was identified to maintain stable performance of membrane. Ozonation was used to treat 550 mL combined eluent in batch mode. The TOC removal increased with time and reached the plateau after 1 min. The TOC was reduced by 38 %, while the colour of the combined effluent became lighter after 1 min treatment. As the temperature increased, longer ozonation time was required to inhibit the membrane wetting. For the feed inlet temperatures of 50 °C and 70 °C, the ozonation times of 40 s and 60 s were able to suppress the membrane wetting in the short-term tests. For the fractionated effluent, near zero discharge (water recovery of 98 %) could be achieved without serious wetting issue. To avoid membrane fouling issues, 95 % water recovery is recommended. For the 40 s ozonation pretreated effluent, DCMD could only achieve 38 % of the feed recovery before occurrence of wetting.

Synthesis of Nitrogen‐Doped CNT‐Based MOF Hybrids for Adsorptive Desulfurization of the Gas Stream

AbstractIn this research, hybrids of N‐doped carbon nanotube (NCNT)‐based metal‐organic framework (MOF) (NCNT/UiO‐66 and NCNT/ZIF‐67) were synthesized using hydrothermal method. The performance of synthesized hybrids was evaluated in hydrogen sulfide removal under a dynamic system at 30–50 °C with 4500 ppm H2S concentration as inlet feed compared with neat UiO‐66 and ZIF‐67. NCNT/UiO‐66 and NCNT/ZIF‐67 were characterized using XRD, FTIR, FESEM, BET, and TGA. NCNT/ZIF‐67 and NCNT/UiO‐66 showed good adsorption capability for H2S with a capacity of 189.72 mg/g and 175.77 mg/g, respectively. The surface area of UiO‐66 and ZIF‐67 is (1351 and 1290 m2/g, respectively), and the addition of NCNT leads to the reduced surface area of nano adsorbent hybrids. Also, the performance of hybrids would not change after three cycles of the desulfurization process. These hybrids indicated the excellent potential for a desulfurization process.

OPTIMIZATION OF SPRAY DRYING CONDITION FROM TRAMETES VERSICOLOR MUSHROOM EXTRACT

In this study, the optimal conditions for the spray drying from Trametes versicolor (V.C.) extracts were determined using response surface method/technique (RSM). One kilogram of material was extracted with 30L ethanol 65% of 70oC for 7 hours. Solids were filtered off, extract was concentrated to obtain solution containing about 20% total solid using a vacuum evaporator. Study on the effects of three independent variables, namely maltodextrin ratio (% w/v), feed flow rate (ml/min) and inlet drying temperature (oC) on the responses; total phenolic content (TPC) and moisture content (MC). The optimal conditions for spray drying process from T. versicolor extracts were found to be maltodextrin ratio of 5%w/v, inlet drying temperature of 160oC and feed flow rate of 26.05ml/min. The experimental values of TPC and MC were 35.76±0.04mg GAE/g, 4.43±0.02%

Direct contact membrane distillation for liquid desiccant regeneration and fresh water production: Experimental investigation, response surface modeling and optimization

Liquid desiccant cooling (LDC) systems are being widely considered as a promising alternative for energy savings and the regeneration is one of the most significant processes of the LDC systems. This paper presents a direct contact membrane distillation (DCMD) regenerator for liquid desiccants regeneration of LDC systems and fresh water production simultaneously. The novelty of this study is to use the response surface method to establish models to predict the DCMD regeneration performance with highly concentrated lithium chloride solutions based on the experimental investigation. The interactive effects of the operating parameters, i.e. initial feed concentration, feed inlet temperature, distillate inlet temperature, and feed and distillate flow rates were studied and the optimal conditions of the DCMD regenerator to maximize the feed concentration increase and transmembrane water flux were identified. The experimental results showed that stable regeneration performance and water production with the lithium chloride salt rejection rate over 99.99% by the membrane were achieved using the DCMD regenerator. The temperature difference between the feed and distillate sides should be controlled higher than a threshold to ensure continuous liquid desiccant regeneration. Initial feed concentration and flow rate exhibited a significant interaction in improving the DCMD regeneration performance. An optimal flow rate for better regeneration performance can be observed when increasing the initial feed concentration. The optimization results showed that the feed concentration increase and transmembrane water flux can be improved by 39.7% and 41.6% respectively under the optimal conditions as compared to the best case observed in the response surface method designed experiments.

Insights into nucleation and growth kinetics in seeded vacuum membrane distillation crystallization

A seeded vacuum membrane distillation crystallization (VMDC) process for treating magnesium sulfate solution was proposed. The permeate flux was investigated with respect to feed inlet temperature, vacuum pressure and feed velocity in order to determine operating conditions of VMDC. For the VMDC, the inlet and outlet temperatures of membrane distillation were maintained at 84 °C and 68 °C respectively, and the vacuum was 0.04–0.07 MPa. The nucleation and growth kinetics with the presence of seed in VMDC were investigated by comparison with the evaporation crystallization. Crystal nucleation and growth rates in evaporation crystallization and VMDC were both calculated using the population balance equation. It was found that the crystal growth rate in VMDC was slightly less than that in evaporation crystallization. Compared with evaporation crystallization, the secondary nucleation rate in VMDC was reduced due to the decrease of collision frequency between crystals.

Performance evaluation of shell and tube heat exchanger through ANN and ANFIS model for dye recovery from textile effluents

ABSTRACT Performance of Shell and Tube Heat Exchanger for treatment of textile industry wastewater as a secondary treatment process is reported. An Adaptive Neuro-Fuzzy Inference System and Artificial Neural Network models were used for predicting the accuracy of the process. Condensate flow (m3/hr), feed inlet temperature (°C) and steam flow (kg/cm) for textile effluents were used to predict the condensate temperature (°C). The accuracy of the developed model was validated using Absolute Mean Relative Error, Root Mean Square, and Absolute fraction of variance. The different combinations of input parameters were determined with preceding parameters of the model. Comparison of the models indicated the advantage of ANFIS model over ANN model. Seventh configuration values of ANN reported 0.971%, 1.175%, and 0.9456 of the Absolute Mean Relative Error, Root Mean Square, and Absolute fraction of variance respectively. Similarly, the ANFIS reported 0.381%, 0.532%, and 0.9998 of the Absolute Mean Relative Error, Root Mean Square, and Absolute fraction of variance respectively. ANFIS model was found to be more effective in predicting the condensate temperature with a high Absolute fraction of variance R2 = 0.9998 the results were in line with the experimental data. In the present study the complication of nonlinear process has been resolved using ANFIS modeling technique. The treated water could be recycled using this process. Optimization of the process parameters helps in minimizing water consumption and offers economic benefits for wastewater treatment.

Artificial neural networks modelling for biodiesel production from waste cooking oil

The objective of the present work is to develop models inculcating the effect of operating conditions of waste cooking oil methyl esters production in the reactive distillation column, namely waste cooking oil (WCO) flow rate, methanol/WCO molar ratio, reboiler heat duty and feed inlet temperature on the estimation of parameters like the biodiesel conversion by using Artificial Neural Networks technique. In our study, at the maximum biodiesel conversion of 99.48% and at steady state time of 1.69 hour were determined as WCO flow rate of 2.90 ml/min, methanol/oil molar ratio of 8.19 and reboiler heat duty of 0.419 kW. Experiments were conducted in the laboratory and the results obtained were used to develop the ANN model using MATLAB. The developed model was in good agreement with the experimental values.

Numerical investigation of hydrodynamics and crystal growth in a forced circulation crystallizer

Industrial waste and brine discharge into nature, has had destructive effects on the environment; solution to which is using Zero Liquid Discharge (ZLD) waste water treatment. Crystallizer as a heart of Zero Liquid Discharge process undertakes creating and growing crystals from the inlet feed solution. Studying the hydrodynamics of the flow assisted by Computational Fluid Dynamics (CFD) is a powerful method of identifying microscopic phenomena in crystallizers. The present paper simulated a common industrial Forced Circulation (FC) crystallizer using the two phase Euler-Euler model, assisted by kinetic theory of granular flow. Turbulence is accounted for by Reynolds Stress Model (RSM), while inter-particle interactions are considered using the Population Balance Model (PBM). Results showed that approximately 65% of the increase in size of crystals happens in the boiling and mixing zone of the crystallizer. Applying the growth rate of 5e-9 [m/s], breakage and aggregation in the crystallizer dominates, contributing 84% of total size increase; while increasing the growth rate and reaching the value of 5e-7 [m/s] results in the growth mechanism surpassing the other mechanisms, contributing 55% of total size increase. Additionally, by 10% increase in particles concentration at the inlet, particles mean diameter at the outlet increases about 6.2%.