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Membrane Module Design & Analysis for Gas Separation

Thesis Info

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Author

Muhammad Ahsan

Program

PhD

Institute

National University of Sciences & Technology

City

Islamabad

Province

Islamabad

Country

Pakistan

Thesis Completing Year

2016

Thesis Completion Status

Completed

Subject

Energetic Materials Engineering

Language

English

Link

http://prr.hec.gov.pk/jspui/bitstream/123456789/9919/1/Muhammad%20Ahsan-%20PhD%20Thesis%20Complete.pdf

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676726632298

Similar


The expected worldwide market for membrane separation technologies is estimated to be $16 billion by the year 2017 because of extensive acceptance of the membrane technology in several end-user markets. With the increase in demand for high-quality products, environmental concerns, stringent regulations and exhausting natural resources, membrane separation technologies are predicted to see substantial development in the future. The scope of membrane technology likely is expected to be interesting as new membrane materials, innovations and processes make their way to the marketplace. The recent development in industrial applications of membrane gas separation is: to develop robust membranes, which show higher separation capacity, and are consistent and durable for specific applications. Process simulation is a method to optimize the design and operating conditions in the process. A process configuration and optimum operating conditions result in enhanced separation performance and are less expensive. In addition, with the growth of new process models, new membrane applications are arising. This study focuses on emerging models that can be used to bring improvement in the operation and design of membrane gas separation processes. Numerical models for the better performance of gas separation with high permeation were developed and verified. The pressure gradient on both sides of the membrane in different flow patterns has been considered i.e. co-current, cross and counter current. The numerical models are useful as they need least computational effort and deliver better solution stability. The robustness and the predictions of the numerical models were verified with experimental data for different membrane systems with different flow patterns. The numerical models were applied to several case studies to investigate the performance of different membrane module configurations. The research shows that the new numerical models can effectively handle the high permeate membrane problems with various flow configurations. It is a common perception that working at higher pressures permeates more gasses, and hence, occasionally the membrane module is analyzed or characterized at lower pressures to save gas utilization. It is also believed that membrane ability of gas separation declines at higher feed pressures. The obvious and key permeances of different grasses for different membranes were assessed from numerical analysis based pure gas permeation experiments reported in the ii literature. It was found that the membrane performs near to its real separation capability if it is worked at high feed pressures. The effect of pressure on the membrane performance is minimized under some special conditions. One of the most powerful features of the ASPEN HYSYS program enables users to add additional unit operations to the program through Extensibility. Using this capability, the ASPEN HYSYS could be customized for the simulations to match specific operating conditions. The built in unit operation of membrane is not available in ASPEN HYSYS. In this research, a membrane extension has been developed in ASPEN HYSYS. Developing and implementing the successful Extensions for ASPEN HYSYS requires a good understanding of the ASPEN HYSYS program, an object-oriented programming language (Visual Basic), and the purpose of the Extension. This research will help combine the knowledge of all three areas and allow us to create useful and powerful extensions for the ASPEN HYSYS program. This extension allows ASPEN HYSYS to simulate the industry specific membrane based separation processes. Computational fluid dynamics (CFD) simulations were carried out for the separation of gasses using membranes. This CFD code was used to examine the flow profile for gas separation in a membrane. To the best of our knowledge, the availability of CFD simulation on membrane gas separation is found to be limited, hence, it was attempted in the present study. The aim of this research is to use commercial CFD simulation package ANSYS FLUENT to predict flow conditions and gas permeation. For CFD calculations, the commercial solver based on finite volume method (FVM) has been used and the mass transfer through the membrane has been modeled by user-defined functions (UDFs). Two key aspects are significant for the design of membrane modules used for gas permeation. These aspects include flow distribution and concentration polarization. The later causes a reduced driving force, considerably affecting membrane performance. A uniform flow distribution will ensure that the complete membrane area is utilized. In order to reduce the influence of concentration polarization and to ensure an even flow distribution, baffles located between two membrane surfaces or plates containing flow channels are employed. Turbulence model has been integrated into the solution of incompressible flow equations.
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بھانویں چھڈیا ککھ وی نئیں

بھانویں چھڈیا ککھ وی نئیں
دل فیر تیتھوں وکھ وی نئیں
سارا حسن ایہہ دنیا دا
اوہدی تاں اک اکھ وی نئیں

Multiple Intelligences: Learners VS Teachers

The study investigated the relationship of the multiple intelligences of the Bachelor of Secondary Education students and their teachers in their major subjects. Four hundred eighty-five (485) BSED students and twenty-two (22) teachers in their respective major subjects participated. The result demonstrates statistically significant in the multiple intelligences of the Bachelors of Secondary Education Major in Technology and Livelihood Education and Music, Arts, Physical Education and Health and their teachers in their respective major subjects. However, result also demonstrates no significance in the multiple intelligences of the Bachelors of Secondary Education Major in Filipino, English, and Mathematics and their teachers in their respective major subjects. The study shows that the dominant intelligences of the BSED students and their teachers in their major subjects are the interpersonal, intrapersonal, and their suited intelligences for their major subjects. The result evidently showed that the BSED students and their major teachers are people and self smart. This only shows that as a teacher, one should know how to socialize appropriately with others and have a deeper understanding with themselves. It also showed that the teachers are really smarter than their students in their major field of specialization. Educators must also consider the multiple intelligences of their students to fully develop their learning capabilities.

Ecofriendly Control of Culex Quinquefasciatus Say 1823 and Susceptibility of its Larvae and Predators to Different Environmental Pollutants

Culex quinquefasciatus (Say.) is a common and abundant mosquito species that causes serious nuisance through its irritating biting and acts as the vector of Wuchereria bancrofti that causes filariasis (also called elephantiasis) in different parts of the world. Control of mosquitoes is important for the protection of people and livestock from mosquito-borne diseases and from their nuisance biting. The constant use of synthetic insecticides has resulted in the development of insecticide resistance in insect pests, contamination of the environment, and adverse effects on humans and other non-target organisms. Plant based insecticides are gaining attention as they are biodegradable, safe, eco-friendly and effective. Control of mosquito population through the application of natural predators is also highly appreciated as this approach is also ecofriendly and effective. During the present research, three native medicinal plants i.e., Chenopodium ambrosioides (Linn.), Chenopodium botyrs (Linn.) and Cymbopogon nardus (Linn.) were evaluated for their mosquitocidal activities. The whole- plant n-hexane extracts of C. ambrosioides, C. botyrs and C. nardus were evaluated for larvicidal, pupicidal, adulticidal, oviposition deterrence and adult emergence inhibition activities against Cx. quinquefasciatus. The n-hexane extract of C. ambrosioides whole- plant was found most effective against the larvae (LC50 against 4th instar larvae = 204.2 ppm), pupae (LC50 = 1154 ppm) and adults (KDT50 at 1.25 % concentration = 28.4 minutes, KDT50 at 0.138 mg/cm2 = 8.4 minutes). Therefore, this extract was subjected to fractionation through column chromatography. The fractions obtained (F1 to F3) were then tested for adulticidal activity. The F1 fraction caused 100 % adult mortality at 1.5 % concentration. This fraction was further subjected to fractionation through column chromatography and the resultant six subfractions (F1.1 to F1.6) were then tested for adulticidal activity. Two subfractions of F1 fraction i.e., F1.1 and F1.5 showed strong adulticidal activity. The LC50 values of subfractions, F1.1 and F1.5 were 0.133 mg/ml and 0.130 mg/ml, respectively. The n-hexane extracts of all the three plants showed oviposition deterrent activity. For example, during oviposition deterrent activity at 31.25 ppm, maximum percentage of effective repellence (% ER) was shown by C. botyrs (37.1±8.7 %) followed by C. ambrosioides (29.3±5.5 %) and C. nardus (13.4±1.3 %). Minimum oviposition activity indices (OAI) value was observed for C. botyrs (-0.3±0.1) followed by C. ambrosioides (- 0.15±0.03) and C. nardus whole- plant (-0.1±0). The n-hexane extracts of all the three plants also showed adult emergence inhibition activity. Significantly lowest EI50 (EI stands for emergence inhibition) value was exhibited by C. ambrosioides (EI50= 139.3 ppm) followed by C. botyrs (EI50=312.3) and C. nardus extract (EI50=515.2). The n-hexane extracts of C. ambrosioides, C. botyrs and C. nardus whole- plants showed no toxicity against non-target organisms i.e., Odonate nymphs (Ischnura elegans and Sympetrum decoloratum), fish (Ctenopharingodon idella) and mammal (domestic rabbit of Oryctolagus cuniculus species). Damselfly (order Odonata, sub order Zygoptera) and dragonfly (order Odonata, sub order Anisoptera) nymphs have the predatory ability and share habitat with the immature stages of mosquitoes therefore they can be considered good biological control agents against larvae of mosquitoes. During the present study, the nymphs of damselfly (Ischnura elegans) and dragonfly (Trithemis aurora, Pantala flavescens, Libellula fulva, Sympetrum decoloratum and Crocothemis servilia) showed predatory ability against Cx. quinquefasciatus 3rd instar larvae in the laboratory. Among these nymphs, P. flavescens nymph was found most efficient predator of mosquito larvae. A single P. flavescens nymph consumed 47.0 ± 5.1 Cx. quinquefasciatus 3rd instar larvae per day. Mosquito larvae and their predators (damselfly and dragonfly nymphs) that share the aquatic habitat face increasing environmental pressure due to increasing urbanization and human activities. Therefore, there is the requirement of study for understanding the levels of environmental pollutants to which mosquito larvae and their predators are susceptible. Mosquito (Cx. quinquefasciatus) larvae and their predators were exposed to different environmental pollutants to determine the lowest level of pollutants to which mosquito larvae and their predators are susceptible or to determine the highest level of pollutants which the mosquito larvae and their predators can tolerate. During the study of susceptibility of Cx. quinquefasciatus larvae to different inorganic nutrient pollutants, the minimum concentrations of ammonium (NH4+), nitrate (NO3–) and (PO4–3) that caused mortality of Cx. quinquefasciatus 2nd instar larvae for 48 hours exposure was 20, 100 and 300 ppm, respectively. The gravid female Cx. quinquefasciatus adults preferred to oviposit in containers containing 5 ppm NH4+, 45 ppm NO3– or 30 ppm PO4–3 solution but did not prefer to lay eggs in control container or containers having higher concentration of NH4+ (10 ppm), NO3– (90 ppm) or PO4–3(60 ppm). No significant effect of NH4+, NO3– or PO4–3 on egg hatching rate was observed. The larvae that existed in containers containing NH4+ (5 ppm), NO3– (45 ppm) or PO4–3(30 ppm) solutions reached earlier to pupal and adult stages. Maximum percentage of these larvae reached to pupal and adult stages. The adults emerged from these larvae showed significantly higher female to male ratio as compared to control adults (P<0.05). These findings show that the levels of NH4+(5 ppm), NO3– (45 ppm) or PO4–3 (30 ppm) recommended by WHO (2006) for wastewater reuse in agricultural irrigation are favorable for the survival and development of Cx. quinquefasciatus mosquito, however higher levels of NH4+, NO3– or PO4–3 are not favorable for the survival and development of Cx. quinquefasciatus mosquito. During the study of susceptibility of Cx. quinquefasciatus 2nd instar larvae to heavy metals, the minimum concentration of lead (Pb), cadmium (Cd) and copper (Cu) that caused mortality of Cx. quinquefasciatus second instar larvae for 48 hours exposure was 0.5 ppm, 0.3 ppm and 0.25 ppm, respectively. The gravid female Cx. quinquefasciatus adults did not prefer the 0.5 ppm Pb or 1.0 ppm Cu solution for oviposition. Exposure of Cx. quinquefasciatus 1st instar larvae to 0.5 ppm Pb, 0.1 ppm Cd or 1.0 ppm Cu resulted into prolonged time to pupation and time to adult emergence and increased female to male ratio. These finding show that the levels of Pb (0.5 ppm), Cd (0.1 ppm) or Cu (1 ppm) recommended by Pakistan EPA (1997) in municipal and liquid industrial effluents, are not favorable for the survival and development of Cx. quinquefasciatus mosquito. During the study of susceptibility of predators of mosquito larvae to inorganic nutrient pollutants, I. elegans, T. aurora and P. flavescens tolerated high concentration of ammonium (up to 50 ppm), nitrate (up to 150 ppm) and phosphate (up to 250 ppm) for seven days under condition of neutral pH and room temperature. P. flavescens was found least susceptible to these pollutants. During the study of susceptibility of predators of mosquito larvae to heavy metals, the nymphs of I. elegans, T. aurora and P. flavescens tolerated high level of Pb (up to 40 ppm), Cd (up to 40 ppm) and Cu (up to 10 ppm). P. flavescens was found least susceptible to these heavy metals. These levels of Pb, Cd or Cu which the odonate nymphs tolerated is far above the concentration to which odonate nymphs would be exposed in the field. During the study of susceptibility of I. elegans and T. aurora to agricultural insecticides, the nymphs were found most susceptible to lambdacyhalothrin but least susceptible to chlorpyrifos. The LC50 values of lambdacyhalothrin and chlorpyrifos against I. elegans were 0.004 ppm and 0.142 ppm, respectively. Similarly, the LC50 values of lambdacyhalothrin and chlorpyrifos against T. aurora were 0.005 ppm and 0. 257 ppm, respectively. From the findings of the study of mosquitocidal activities of plant extracts, it is concluded that the n-hexane extracts of C. ambrosioides, C. botyrs and C. nardus wholeplants exhibit appreciable mosquitocidal activities. These extracts exhibit no toxicity with non-target organisms i.e., damselfly and dragonfly, fresh water fish (grass carp) and mammal (rabbit). Among the three plants studied during the present research, the n-hexane extract of C. ambrosioides is most efficient in larvicidal and adulticidal activities. The F1 column chromatographic fraction of C. ambrosioides n-hexane extract exhibit strong adulticidal activity. Two subfractions of F1 fraction i.e., F1.1 and F1.5 exhibit strongest adulticidal activity against Cx. quinquefasciatus, suggesting the presence of mosquitocidal compounds in these subfractions. From the findings of the study of predatory ability of damselfly and dragonfly nymphs, it is concluded that the nymphs of I. elegans, T. aurora, P. flavescens, L. fulva, S. decoloratum and C. servilia have the predatory ability against Cx. quinquefasciatus larvae. The nymph of Pantala flavescens is the most efficient predator of mosquito larvae among all the nymph species tested. From the findings of the study of susceptibility of Cx. quinquefasciatus larvae to different inorganic nutrient pollutants, it is concluded that the levels of NH4+, NO3– or PO4– 3 recommended in effluents for wastewater reuse in agricultural irrigation by WHO (2006) are favorable for the survival and development of Cx. quinquefasciatus mosquito, however higher levels of NH4+, NO3– or PO4–3 are not favorable for the survival and development of this mosquito. From the findings of the study of susceptibility of Cx. quinquefasciatus larvae to heavy metals, it is concluded that the levels of Pb, Cd or Cu recommended by Pakistan EPA (1997) in municipal and liquid industrial effluents are not favorable for the survival and development of Cx. quinquefasciatus mosquito. From the findings of the study of susceptibility of predators of mosquito larvae to inorganic nutrient pollutants, it is concluded that I. elegans, T. aurora and P. flavescens can tolerate high concentration of NH4+, NO3–and PO4–3 under condition of neutral pH and room temperature. From the findings of the study of susceptibility of predators of mosquito larvae to heavy metals, it is concluded that I. elegans, T. aurora and P. flavescens nymphs can tolerate high level of Pb, Cd and Cu contamination in water. The level of Pb, Cd or Cu which the odonate nymphs tolerated is far above the concentration to which odonate nymphs would be exposed naturally in the field. From the findings of the study of susceptibility of predators of mosquito larvae i.e., I. elegans and T. aurora to agricultural insecticides, it is concluded that deltamethrin, cypermethrin, lambdacyhalothrin, chlorpyrifos, dichlorvos and acetamiprid are hazardous to predators of mosquito larvae at very low concentrations. The application of these synthetic chemical insecticides should be minimized and safe application in the areas adjacent to aquatic habitats must be ensured. Application of other methods of insect pest control such as integrated pest management should be encouraged." xml:lang="en_US