Masoud Rahimi

  atural convection inside a partitioned enclosure has attracted much attention in recent years due to its importance in engineering applications for weakening or enhancing the intensity of heat transfer. In this study, a vertical enclosure containing air partitioned by a row of horizontal flat insulating blades is investigated. The effects of effective variables on the steady laminar natural convection flow inside the partitioned enclosure are numerically studied. Different temperatures are considered for the side walls of the enclosure, while the other walls are insulated. The row of blades is unsymmetrical in two cases; in one case, the row of blades is moved away from the symmetry line of the enclosure and towards the hot wall, and in the other case, the row of blades is moved away from the symmetry line of the enclosure and towards the cold wall. The effective variables include the Rayleigh number (Ra) in the range of 103×7 and 1.45×104, the angle of inclination of the blades to the horizon (?) in the range of 0 to 180 o and the eccentricity (S) in the range of -1.5 to +1.5 mm. Based on the numerical results obtained, the heat transfer is particularly sensitive to the change in the angle of the blades (?) and has an oscillating trend towards it. In addition, the heat transfer increased with increasing the Rayleigh number (Ra). Also, the asymmetric arrangement of the blades inside the chamber reduces the heat transfer in the chamber by a maximum of 19% compared to the symmetrical arrangement (S=0). In fact, with a low-cost geometric change, a significant amount of heat transfer in the chamber is reduced.

Lithium-ion batteries, as primary energy sources in electric vehicles, energy storage systems, and high-power electronic devices, face significant challenges related to temperature rise and thermal management. Increased internal battery temperature not only reduces efficiency and service life but also poses serious safety risks such as thermal runaway, fire, and electrode damage. Therefore, developing effective methods to control temperature, delay critical temperature rise, and homogenize heat distribution is a fundamental aspect of lithium-ion battery design and performance improvement. One advanced approach in thermal management is the use of phase change materials (PCM), which have the capacity to store and release latent heat and can prevent rapid temperature increases by absorbing the heat generated by the battery. This thesis investigates and analyzes the performance of various phase change materials including paraffin, vaseline, and their composites with conductive additives such as graphite, copper oxide, and alumina+CuSO?, evaluating their effects on the thermal behavior of lithium-ion batteries comprehensively. In this study, more than 23 different phase change material compositions with varying ratios of paraffin and vaseline and different amounts of conductive additives were examined. The experiments included recording the battery temperature rise time, heating rate, and heat distribution uniformity at different voltages, along with comparing thermal behavior with and without conductive additives. These data enabled precise analysis of the impact of different PCM compositions on battery thermal management and identification of optimal mixtures. The results showed that pure paraffin compounds, due to high latent heat capacity, extended the temperature rise time but exhibited non-uniform temperature distribution and hotspot formation on the battery surface because of low thermal conductivity. Pure vaseline, though structurally stable and reducing PCM leakage, had a higher heating rate and lower heat storage capacity. With the addition of graphite and other conductive additives, heat transfer improved and temperature distribution became more uniform. Compositions containing graphite and copper oxide or alumina+CuSO? showed the longest critical temperature time and lowest heating rates, providing optimized thermal performance along with suitable mechanical stability. Also, paraffin–vaseline mixtures with graphite achieved a good balance of thermal energy storage, structural stability, and temperature uniformity and were suitable for moderate charge-discharge cycles. Ranking analysis revealed that the best thermal performance was related to PCM base compositions with conductive additives, while pure vaseline and pure paraffin without additives showed the lowest efficiency in thermal management. Findings indicate that selecting the optimal PCM composition combined with conductive materials is crucial for achieving stable thermal management, enhancing safety, and prolonging the lifespan of lithium-ion batteries. This thesis serves as a scientific and practical guide for designing advanced thermal management systems in electric vehicles and industrial applications of lithium-ion batteries, highlighting the importance of intelligent PCM and conductive additive combinations in improving battery thermal performance.   

Ejectors, as essential devices in industrial processes, play a vital role in energy transfer and fluid suction. In this thesis, the performance of an air ejector experimentally investigated by Tang Liu and co-workers was studied using Computational Fluid Dynamics (CFD) in a two-dimensional axisymmetric model. The main objective of the study was to analyze the effects of nozzle throat diameter and mixing chamber diameter on the entrainment ratio, the influence of primary and secondary flow pressures on entrainment ratio and critical back pressure, and to compare the simulation results with experimental data, which showed good agreement. Velocity, pressure, and Mach number contours were plotted and analyzed under different operating conditions. The results indicated that increasing the nozzle throat diameter reduces the entrainment ratio but raises the critical back pressure. Enlarging the mixing chamber diameter increases the entrainment ratio while decreasing the critical pressure. Moreover, the maximum entrainment ratio was observed with a larger mixing chamber and a smaller nozzle. The effects of primary and secondary flow pressures on mass flow rate and entrainment ratio were also investigated. It was found that, for all geometries, an increase in primary flow inlet pressure increases the primary mass flow rate, whereas the entrainment ratio or entrained mass flow initially rises and then decreases. The increase in secondary mass flow rate was attributed to higher nozzle exit velocity at elevated primary pressures, which enhances suction. However, beyond a certain limit, further increases in primary pressure cause excessive expansion of the converging-diverging nozzle flow, blocking the secondary stream, as confirmed by Mach number contours. Furthermore, with a constant nozzle throat diameter, higher primary flow pressure results in an increased maximum entrainment ratio and a higher corresponding optimum primary pressure. In contrast, with a fixed mixing chamber diameter, increasing the nozzle throat gradually decreases the maximum entrainment ratio and lowers the optimum primary pressure. It was also observed that ejectors with smaller nozzle throats require higher secondary pressures to initiate operation. Results further revealed that, when the nozzle size is fixed and the mixing chamber diameter gradually increases, the minimum secondary pressure required for startup increases, and the entrainment ratio grows more rapidly with increasing secondary pressure. Conversely, with a fixed mixing chamber diameter, reducing the nozzle throat diameter leads to a faster rise in entrainment ratio with increasing secondary pressure. Finally, recommendations for future research were proposed, including three-dimensional simulations, multiphase flow analysis, multi-parameter optimization, investigation of working fluid effects, and transient flow studies. The findings demonstrate that numerical simulation is a powerful tool for analyzing and optimizing high-performance industrial ejectors.  

   نفت خام سنگين به دليل ويسكوزيته بالا، محتواي بالاي آسفالتين و رزين و دشواري در فرآورش همواره يكي از چالش‌هاي اصلي صنايع پالايشي محسوب مي‌شود. يكي از رويكردهاي نوين براي بهبود فرآورش اين برش‌ها، بهره‌گيري از پديده كاويتاسيون و انرژي آزادشده از انفجار حباب‌ها به‌عنوان منبعي براي تغيير خواص نفت سنگين است. در اين تحقيق، شبيه‌سازي عددي پديده كاويتاسيون در يك اجكتور در مقياس آزمايشگاهي با استفاده از ديناميك سيالات محاسباتي انجام شد. هندسه اجكتور در نرم‌افزار انسيس ديزاين مدلر طراحي و شبكه‌بندي آن در انسيس مشينگ انجام شد. شبيه‌سازي جريان سه‌فازي (آب، بخار و نفت سنگين) و پديده كاويتاسيون با استفاده از مدل جريان مخلوط در انسيس فلوئنت انجام گرديد. شرايط مرزي شامل فشار ورودي آب Pa 2.000.000 و دماي   K298 و فشار ورودي نفت سنگين Pa80000 و دماي   K353 بود، در حالي كه فشار خروجي برابر با Pa 101325 تعيين شد. دبي ورودي نفت در شرايط مرزي فوق به ترتيب Kg/s4709171/0 بود و حداكثر سرعت در گلوگاه اجكتور m/s 39/ 63 گزارش شد. داده‌هاي به‌دست‌آمده از فلوئنت شامل فشار و حجم بخار توليدي (m³/s 104×33/7) به نرم‌افزار متلب منتقل شد و با بهره‌گيري از معادله ريلي پلست، ديناميك فروپاشي حباب‌ها و انرژي آزادشده از انفجار آن‌ها محاسبه گرديد. دما و فشار حباب حين فروپاشي به ترتيب،   K98/4722 و bar 2827 انرژي آزادشده از يك حباب در اين فرآيند J 10-10 833× /1بود كه به عنوان بار حرارتي به جريان نفت سنگين اعمال شد. تحليل نتايج نشان داد دانسيته نفت پس از كاويتاسيون از Kg/m³1/903 به 1/880 كاهش يافت و ويسكوزيته ازKg/m·s 2467/0 به 0754/0 كاهش يافت، كه بيانگر تغيير قابل توجه در خواص ترموديناميكي نفت سنگين است. بر اساس نتايج به‌دست‌آمده، بهره‌گيري از كاويتاسيون و طراحي بهينه اجكتور مي‌تواند رويكردي مؤثر براي بهبود فرآيندهاي شكست مولكول ها و سبك‌سازي برش‌هاي سنگين نفت باشد. چارچوب روش‌شناسي ارائه‌شده، امكان تحليل همزمان هيدروديناميكي، ديناميكي و اثرگذاري انرژي آزادشده از كاويتاسيون بر نفت را فراهم مي‌آورد و مي‌تواند مبناي توسعه تحقيقات آينده در بهينه‌سازي فرآيندهاي پالايشي قرار گيرد.

   Combustion, as one of the primary methods of energy conversion in various industries, plays a vital role in energy production and heating. Despite significant advancements in renewable energy technologies, fossil fuels still constitute a major share of global energy supply. This study investigates the combustion process in industrial boilers using Computational Fluid Dynamics (CFD) methods and analyzes system performance optimization with a focus on pollutant reduction and efficiency enhancement. In this research, the theoretical fundamentals of combustion, its various types, and the relevant chemical and physical mechanisms are first outlined. A three-dimensional simulation of a water-tube boiler used at Ilam Gas Refinery was then conducted using ANSYS Fluent software. Key parameters such as temperature distribution, fluid velocity, and pollutant concentrations under different operating conditions were examined. The results revealed that adjusting the excess air ratio and optimizing burner design could significantly reduce emissions of nitrogen oxides (NOx) and carbon monoxide (CO). Moreover, the use of blended fuels—such as mixtures of methane with ethane-propane—was found to maintain boiler efficiency while decreasing pollutant levels. Additionally, the influence of boiler geometry and tube arrangement on heat transfer and pressure drop was analyzed. The findings indicated that an optimized design could enhance thermal efficiency by up to 5%. Finally, several strategies were proposed for improving boiler performance and minimizing environmental impacts, including the application of advanced combustion technologies, waste heat recovery, and precise control of operational parameters. As an applied research study, this work provides a foundation for the more efficient design and operation of industrial boilers and demonstrates that integrating numerical and experimental approaches can lead to significant advances in combustion system optimization. Keywords: Combustion, Industrial Boiler, Computational Fluid Dynamics (CFD), Optimization, Pollutants, Thermal Efficiency.

  One of the major challenges in photovoltaic (PV) panels

   Lithium-ion batteries are the powerhouse of the digital electronic revolution in this modern society. However, a critical issue is the thermal management of these devices' batteries to ensure rapid charging or discharging, safe operation, and efficient performance by regulating their temperature within the optimal range. Nevertheless, existing battery thermal management methods, including air and liquid cooling (known as active cooling), not only occupy significant space but also struggle to overcome battery cooling at high temperatures due to their heavy weight and limited energy consumption, leading to reduced vehicle efficiency. In contrast, passive cooling methods, referred to as phase change material (PCM)-based battery thermal management technology, have demonstrated favorable performance by saving weight and energy consumption. However, the low thermal conductivity and leakage of PCMs have limited their application in battery thermal management. In this thesis, the thermal modeling of a battery using a heater was experimentally investigated. Additionally, several battery thermal management systems, including PCMs with three different mass percentage ratios composed of paraffin and beeswax, and carbon-based aerogel/PCM composites, were fabricated. The results showed that using a PCM composed of 75% paraffin and 25% beeswax alone increased thermal performance by up to 56% compared to the other two ratios. Furthermore, using raw aerogel/PCM composed of 25% paraffin and 75% beeswax resulted in a 31% increase in thermal conductivity compared to the PCM alone. However, black aerogel/PCM composites showed acceptable performance across all ratios and resulted in a 46% increase in thermal conductivity. Overall, the use of a black aerogel/PCM composite composed of 25% paraffin and 75% beeswax was considered the optimal thermal management system due to its highest thermal conductivity.

Lithium-ion batteries have a high energy density, but heat production due to electrochemical reactions and the internal resistance of the batteries increases their temperature. Battery thermal management system plays an important role in maintaining the performance of lithium-ion batteries. Phase change materials (PCM) are widely used in battery thermal management systems due to their low energy consumption, high temperature uniformity, and affordable price, but the low thermal conductivity of PCMs has made their use a challenge. One of the ways to increase the thermal conductivity of PCMs is to insert carbon-based materials such as carbon nanotubes and graphene in PCMs. Due to their high thermal conductivity, these materials lead to strengthening the heat transfer of PCMs.Carbon quantum dots are one of the carbon-based materials that are in the nano-size range and have features such as high surface area to volume, excellent electrochemical activity and the ability to precisely adjust the electrical structure. Therefore, in the present study, a heat management system based on PCM reinforced with carbon quantum dots was presented. The phase change agent consisting of beeswax and coconut oil with different weight ratios was prepared and their physicochemical properties were investigated. Carbon quantum dots were also synthesized by hydrothermal and heating methods using citric acid carbon source and their physicochemical properties were investigated using different methods. Physical and chemical characterization of carbon quantum dots was performed using infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and dynamic light scattering (DLS) techniques.Then, the effect of PCMs reinforced with quantum dot carbon on lowering the battery temperature was investigated. The results showed that the addition of quantum dot carbon to PCM leads to a decrease in temperature in the optimal range of battery performance (less than 40 ?C)  

   In this study, a combination method with fillers was used to prepare anti-fouling polyethersulfone nanofiltration membranes for the removal of pharmaceutical pollutants from aquatic environments. Therefore, graphene oxide nanoparticles functionalized with polyaniline were used to prepare mixed matrix membranes. The effect of the modification method used on the separation performance and morphology of the newly prepared membranes was investigated. To identify the prepared membranes, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction spectroscopy (EDX), contact angle measurement, and pore size and porosity calculation were used. FTIR spectroscopy indicated the formation of functional groups on the surface of the filler. In fact, this analysis emphasized the successfulness of the modification method used in the desired membrane. The results showed that the permeate flux of the modified membrane was about 3.5 times higher than that of the unmodified polyethersulfone membrane. Additionally, the surface-modified membrane had a lower contact angle and superior anti-fouling properties compared to the unmodified membrane. To identify membranes prepared through Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction spectroscopy (EDX), contact angle measurement, and pore size and porosity calculation were used. FTIR spectroscopy showed that functional groups were formed on the surface of the filler. In fact, this successful analysis emphasized the effectiveness of the modification method used in the membrane under study. The results showed that the permeation flux of the modified membrane was about 3.5 times that of the unmodified polysulfone membrane. Additionally, the surface-modified membrane had a lower contact angle and better anti-fouling properties than the unmodified membrane. Comparing the performance of membranes prepared for removing pharmaceutical compounds from aqueous environments indicates that the results are almost similar. However, the removal efficiency of drugs by a mixed matrix membrane containing graphene oxide nanoparticles functionalized with polyaniline at a weight percentage of 0.25 (PES/G-Pu 0.25 membrane) is slightly higher than other membranes due to the greater influence of the filler on the adsorption and surface charge properties of the membrane.   

Abstract

   Abstract In this study, the performance of Solar Chimney   integrated with phase change material and the phase change process of these materials were simulated and analyzed using computational fluid dynamics technique and software   Ansys Fluent software through the two-dimensional geometry. In order to speed up the melting process of the phase change material for a uniform heat flux of 700w/m^2, the inlet and outlet vents of the chimney were closed. The schematic of the system and the dimensions of the geometry were considered similar to reference [26]. Comparison of the results of the present work with the mentioned reference shows that the performed simulations are capable of predicting the performance of solar chimney systems equipped with phase change materials. The results of the simulation showed that by increasing the conductive heat transfer coefficient by 2 and 3 times, the melting time decreases by 9 and 15%, respectively, and by increasing the thickness of the phase change material layer by 1.5 and 2 times, the melting time It becomes 1.62 and 2.3 times respectively. Also, by dividing the thickness of phase changing material layer into two or three equal layers with the same type of material , there was no change in the overall melting time. Finally, by dividing the thickness of the PCM layer into two equal parts and Changing the range of phase change temperature of the nearest layer   to the absorber from (311-316 K) to (307-311 K), the total melting time did not change But the system saves energy in this mode at a faster rate than the single-layer PCM mode.

A heat exchanger is a tool for heat transferring between two fluids with temperature difference, and it is important when we can achieve a lower operating cost and a smaller exchanger size. The concept of miniaturization of the exchanger has required researchers to study microchannels as heat exchangers. Micro exchangers, compared to conventional exchangers, have different performance in heat transfer due to structural differences and other differences. In this research, a flat microchannel with a rectangular cross-section is used to investigate the heat transfer, which has four inlet flows, including two lateral sheath flows (to establish the phenomenon of hydrodynamic focusing) and also two middle sheath flows. The phenomenon of hydrodynamic focusing in this microchannel has led to direct the materials into a flow and by removing the contact between the walls of the device and the reactive flow, it creates a uniform flow. Also, an FRR parameter is defined in this microchannel, which indicates the ratio of the total rate of lateral sheath flows to the total rate of middle sheath flows. The performance of heat transfer in this microchannel is studied by checking different parameters in the inlet flows. For this purpose, we use an immiscible fluid (oil) for lateral sheath flows and (ice water) for middle sheath flows. Therefore, we have two separable phases at the output, and this is a valuable point in using this microchannel. The results showed that in order to establish the phenomenon of hydrodynamic concentration, in addition to using different inlet flow rate ratios according to the characteristic dimensions of the flat micro heat exchanger equipped with side sheath flows, the Reynolds number was placed in the range of laminar flow. It also showed a good agreement. The simulations were based on the experimental data obtained from the experiment. In general, the results of the study of heat transfer in a flat microchannel equipped with side sheath flows showed that with an increase in the key parameter defined as FRR in this type of microchannel and an increase in the oil volume flow ratio, the temperature increases, which leads to an increase in the coefficient Heat transfer and increasing the dimensionless number of Nu. A heat exchanger is a tool for heat transferring between two fluids with temperature difference, and it is important when we can achieve a lower operating cost and a smaller exchanger size. The concept of miniaturization of the exchanger has required researchers to study microchannels as heat exchangers. Micro exchangers, compared to conventional exchangers, have different performance in heat transfer due to structural differences and other differences. In this research, a flat microchannel with a rectangular cross-section is used to investigate the heat transfer, which has four inlet flows, including two lateral sheath flows (to establish the phenomenon of hydrodynamic focusing) and also two middle sheath flows. The phenomenon of hydrodynamic focusing in this microchannel has led to direct the materials into a flow and by removing the contact between the walls of the device and the reactive flow, it creates a uniform flow. Also, an FRR parameter is defined in this microchannel, which indicates the ratio of the total rate of lateral sheath flows to the total rate of middle sheath flows. The performance of heat transfer in this microchannel is studied by checking different parameters in the inlet flows. For this purpose, we use an immiscible fluid (oil) for lateral sheath flows and (ice water) for middle sheath flows. Therefore, we have two separable phases at the output, and this is a valuable point in using this microchannel.

در اين تحقيق، پديده خوردگي سايشي در تجهيزات فرآيندي حامل جريان سيال همراه با ذرات جامد مورد مطالعه قرار گرفت و با استفاده از تكنيك شبيه سازي ديناميك سيالات محاسباتي با بكارگيري نرم افزار كامسول پارامترهاي مؤثر بر خوردگي سايشي بررسي شده‌اند. در اين راستا درون مجراهاي حامل جريان هوا و ماسه با انحناهاي 45،60،90،120،135 و 180 درجه پديده خوردگي سايشي ضمن برخورد ذرات جامد جريان با ديواره لوله وخم شبيه سازي شد نوع ذرات، ماسه و اندازه ذرات موجود در سيال m150? در نظر گرفته شد و مدل‌هاي اصلي خوردگي سايشي شامل مدل Finnie،E/CRC،OKA و DNV در اين شبيه سازي لحاظ شد. براي شبيه سازي جريان سيال با توجه به آشفته بودن جريان از مدل k-? استفاده شد. دماي عملياتي 20?C، سرعت جريان هوا 11M/S و فشار خروجي مجرا 1atm درنظر گرفته شد. نتايج بدست آمده از اين شبيه سازي شامل بررسي پارامترهاي ديناميكي جريان و اثر پارامترهاي مختلف مانند سرعت، اندازه ذرات، دانسيته ذرات، قطر مجرا و...، بررسي مسير حركت ذرات و تشخيص نقاط مهم خوردگي است. بررسي اثر پارامترهاي مختلف بر روي خوردگي سايشي به صورت كمي در قالب نمودار و جدول ارائه شد اما تشخيص نقاط مهم سايش و بررسي پارامترهاي ديناميكي و نحوه حركت ذرات به صورت كيفي گزارش شد. اين نتايج نشان داد كه با افزايش سرعت سيال، دبي ذرات و افزايش انحناي مجرا خوردگي افزايش يافت و با افزايش قطر ذرات، دانسيته ذرات، قطر لوله خوردگي سايشي كاهش يافت. محل بيشتر سايش براي زانويي 45 و 60 درجه در انتهاي انحنا بود. براي زانويي 120 و 135 درجه حداكثر نرخ سايش در وسط خم رخ داد. ضمناً براي خم 180 درجه دو ناحيه با نرخ سايش بالا در زانويي وجود دارد. با تغيير سيال درون لوله از هوا به آب نرخ سايش حدود 90% كاهش پيدا كرد و براي سيال آب با افزايش قطر ذرات نرخ سايش افزايش پيدا كرد.   اهميت مطالعه تجزيه و تحليل ديناميك سيالات محاسباتي براي مطالعه نرخ سايش با استفاده از كامسول پيش‌بيني بهتري از نقاط مهم خوردگي، برنامه‌ريزي اقدامات پيشگيرانه براي كاهش وقوع سايش، برنامه تعمير و نگهداري و صرفه‌جويي در هزينه با كاهش زمان خرابي ارائه مي‌كند.   

با توجه به نياز روز افزون منابع انرژي، سطح مصرف انرژي در جهان افزايش يافته است. از اين رو دسترسي كشورهاي درحال توسعه به انواع منابع جديد انرژي بويژه انرژي هاي پاك اهميت اساسي دارد و با توجه به كم شدن ذخاير محدود انرژي فسيلي و همچنين دلايل زيست محيطي ديگر نمي توان به آن متكي بود. از اين رو استفاده از انرژي هاي پاك مانند انرژي باد مي تواند جايگاه ويژه اي داشته باشد. در اين بررسي عملكرد انواع توربين هاي بادي، بويژه توربين هاي بدون پره و آشنايي با پديده جريان هاي گردابي كه اساس توربين هاي بدون پره را تشكيل مي دهد ارائه شده است. از اين رو در اين راستا طراحي، مدلسازي و شبيه سازي اين نوع توربين هاي بدون پره انجام شد .ابتدا شبيه سازي دو بعدي سيستم هاي گردابي در حالت استوانه ساكن در رينولدز هاي 60 و 40 انجام شد. در ادامه چهار نوع هندسه ي مختلف دايره، نيم دايره، قيف و نيم دايره-مربع طراحي و شبيه سازي دو بعدي گردابي نوساني VIV آن، در اين چهار هندسه ها در رينولدز 51600 انجام و مقادير جابجايي در جهت عرضي، نيرو هاي درگ و ليفت و ضرايب آنها و همچنين الگوي جريان گردابي پشت اين اجسام بررسي شد. مشخص شد كه هندسه ي نيم دايره-مربع بيشترين مقدار فركانس رابا مقدار 5.747 هرتز نسبت به ساير هندسه ها دارد.   در ادامه مهمترين پارامتر تاثير گذار عدد بدون بعد رينولدز بر عملكرد اين نوع هندسه در سه محدوده ي 30000 ، 51600 و 100000 بررسي و مشخص شد هندسه ي مورد نظر در محدوده ي رينولدز 100000 بيشترين تعداد نوسان جابجايي و سرعت و ضريب ليفت را دارد.

راكتور از ديدگاه شبيه سازي بررسي خواهد شد.   

در اين تحقيق از ديناميك سيالات محاسباتي براي شبيه سازي عملكرد يك يا چند كولر هوايي ( بسته به انتخاب اينكه اين مجموعه بايد بر روي اين خط سيال فرايندي نصب باشند) در شرايط موجود استفاده مي شود. نتايج شبيه سازي CFD جهت تاييد اعتبار با داده هاي تجربي موجود مقايسه خواهند شد. پس از تاييد قابليت شبيه سازي CFD ، اثر تغيير پارامترهاي هندسي ( اعم از تغيير گذرهاي لوله هاي سيال فرآيندي، تغيير آرايش هاي سري- موازي در جريان سيال فرآيندي، تغيير در فاصله كولر هاي هوايي نسبت به خط سيال فرايندي، تغيير در زاويه پره ها و ... ) و همچنين شرايط عملياتي بر روي عملكرد كولرهاي هوايي در خط فرايندي مورد نظر از ديدگاه شبيه سازي بررسي خواهد شد. لازم به ذكر است كه در صورتي قرار است قابليت اجرايي هر يك از تغييرات هندسي بررسي شود بايد جوانب مختلف اعم از افت فشار، توزيه مناسب در آرايش هاي موازي و ... مد نظر قرار گيرد. به طور كلي، هدف از بررسي پارامترهاي هندسي بهبود بخشيدن مكانيسم تاثيرگذاري آنها در عملكرد كولر است. بر اين اساس به به روش انتقال حرارت بين هوا و سيال دقت كرد مي توان چنين استنباط كرد كه به علت انتقال حرارت جابجايي اجباري بين هواي محيط و ديوار خارجي لوله هايي كه سيال در آن جريان دارد، دماي ديواره كاهش مي يابد. سپس با توجه به انتقال حرارت هدايتي در ديواره لوله هاي انتقال حرارتي بين ديواره داخلي و خارجي رخ مي دهد و در نهايت مجدداً به علت انتقال حرارت جابجايي بين ديواره داخلي لوله و سيال داخل لوله، سيال داخل لوله ها خنك مي شود. باتوجه به مكانيسم هاي انتقال حرارت موجود در فن هايي هوايي مي توان نتيجه گرفت كه ارائه راهكارهاي متفاوت در هر كدام با هدف افزايش انتقال حرارت مي تواند منجر به افزايش بازده اي كولر هاي هوايي گردد. از طرفي ديگر،   منظور از شرايط عملياتي بررسي دور فن هاي گردش هوا، شرايط دمايي و فشاري سيال ورودي به كولر جهت خنك سازي است. البته در تغيير هر كدام از اين پارامترها براي رسيدن به حالت بهينه جهت افزايش راندمان كولرهاي هوايي بايد شرايط عملياتي تجهيزات بالادست و پايين دست را نيز در نظر گرفت.   

   In the industry, one of the methods of performing the mixing process is the use of equipment called static mixer. This equipment consists of a number of obstacles or fixed elements and causes a distribution mixing of the fluid along the radial and axial direction. In this study, according to the use of static mixer in the process of desalination of crude oil, the experimental set was designed and fabricated to investigate the mixing process of crude oil as the main fluid and process water as the secondary fluid. Experiments were conducted to investigate the mixing process in eight different crude oil and process water flow rates (crude oil from 6 to 20 L/min and process water flow rate from 0.6 to 2 L/min) in the Reynolds number range from 810 to 2697, in order to obtain the required results in the case of not using static mixer elements (empty pipe) and in the case of using three types of mixer elements, such as standard LPD, LPD with holes with D/10, LPD with holes with D/20. All three types of static mixers have 15 mixing elements with diameter of 49.8 mm and a length of 350 mm and a thickness of 2 mm. To examine the quality of mixing from the variance coefficient of five mixing samples at different areas of the static mixer output, and to examine the pressure drop, the pressure in 25 mm before the first element and 25 mm after the last element of each static mixer was used by the pressure sensor that It is connected to a digital display. The results obtained for all different modes of experiments, show that by increasing the amount of Reynolds of the flow, decreasing the variance coefficient (increasing the mixing quality)and increasing pressure drop. Among the tested static mixers, the perforated LPD type with holes with a D/10 has the lowest coefficient of variance (average 0.2%) and the lowest pressure drop (average 2510 Pa). Also, the simulation in the state of without using elements (empty pipe) and static mixer of standard LPD and perforated LPD with holes with a D/10, was done in geometrical and operational conditions such as experimental conditions, and mixing quality parameters and pressure drop were compared using the experimental results and the CFD simulation. Comparison and validation show acceptable agreement of simulation and experimental results. also, the results of the CFD model are presented using existing equations as a pressure drop factor and friction coefficient.    Keywords: mixing process, static mixer, coefficient of variance, pressure drop, CFD simulation, friction coefficient

In recent years, porous liquids have emerged as a new type of porous material that combines the characteristics of permanent porosity and hardness of porous solids and fluidity, rapid heat transfer and mass transfer of liquids. Compared to porous solids, porous liquids have attracted more attention due to their unique physicochemical properties. They have wide application aspects in the fields of gas adsorption and separation, homogeneous catalysis and so on. Porous liquids are usually divided into three categories based on the composition of the host system in porous liquids which are type I, type II and type III. In the design and synthesis of porous liquids, the preparation of type I porous liquids is usually objective and cannot be accurately designed. For porous cage-based porous liquids type II, the design of rigid porous cages is a major part of the liquid design. For a type III porous liquid based on porous nanoparticles such as MOF, the key is to choose a suitable bulk solvent. Due to the widespread use of porous liquids, their production cost is still high and can not be used in industry. Experiments to investigate the formation of stable porous liquid are costly and time-consuming. One way to reduce these costs is to perform molecular dynamics simulations. In this study, the aim is to provide a comprehensive model for examining pairs of selected materials before the experiment. In this research, to confirm the model, the two compounds of triethylene glycol + ZIF-8 and water + ZIF-8 were simulated and matched with the results of experiments presented in the articles due to the lack of penetration of triethylene glycol in ZIF-8 and Also, obtaining the zeta potential of 164.58, which indicated the stability of the suspension, confirmed the correct results of the proposed model. Then, the selected fluid materials were designed in Materials Materials Studio software and using the structures presented for ZIF-8 and HKUST-1 in the papers; molecular dynamics simulations were performed to select the appropriate pair of materials to produce porous liquid in terms of impermeability. The highest error rate was 11.2, which seems appropriate. Here the best compounds in terms of fluid penetration into the solid structure were presented. Then the zeta potential parameter was obtained to evaluate the stability of the compounds presented in the previous step by programming in Lammps software. Finally, the compounds ZIF-8 + 1,3,5-Trimethylbenzene, ZIF-8 + 1,3,5-Triisopropylcyclohexane and HKUST-1 + 1,3,5-Trimethylcyclohexane were presented as the best compounds for the production of porous liquid.   

Copper is a critical mineral that, in optimal concentration, has a significant role in the health and quality of life of living beings. But at the same time, its deficiency or extra amount causes dysfunction of body's vital organs. So the Copper’s concentration measurement is an essential issue in the water safety monitoring field. As recommended by the World Health Organization (WHO) for the maximum allowable concentration of Cu2+ ions in drinking water is 1.5 mg / l. Conventional concentration measurement methods generally require professional performance and access to expensive tools. It shows the importance of developing low-cost, simple, and efficient methods for measuring copper ion concentrations. The use of microfluidic devices is a good option for analytical experiments due to its speed in analysis, reduction of sample consumption, reagents, solvents, and less waste generation. However, high production costs are an essential obstacle to the widespread use of these devices globally. The use of threads used in the textile industry can be considered as an effective solution to solve this problem. This study aimed to achieve a suitable geometry for microfluidic and find a suitable thread with fluid transfer capability to recognize copper ions. In this regard, by performing various experiments in several stages to investigate the micro-mixing due to the deformation of microfluidics based on different yarns with acid and base solutions, macro mixing with food colors, and finally, the detection of copper ions based on the color change resulting from the reaction of Potassium iodide with copper ions using a T-shaped microfluid based on nylon 66 grade 1880 denier yarn has investigated.Finally, through the reaction of copper with potassium iodide, microfluidic geometry's effect on the rate of fluid advancement in the mixing channel and the quality of fluid mixing based on polyester yarns have been investigated. The investigation results of the thread grade (microfluid channel diameter) change effect on the rate of fluid progress in this study show a direct relationship between increasing thread diameter and the rate of fluid progress. However, this increasing trend is not continuous, and with increasing the yarn grade from 1670 to 2200 deniers, the length of fluid advancement in the mixing channel decreased. In the experiment of double twist Nylon 6 and Nylon 66 yarns with grades 940, 1400, and 1880 Deniers in three types of microfluidics with T, ? and Y-shaped geometries, it was observed that the highest rate of progress has occurred in microfluid with double twist 1880 Denier Nylon 66 yarn. Then, using the reaction of potassium iodide with copper ion, polyester yarns with different scores in three types of microfluidic geometry were investigated, and the microfluid ?-shape still had the highest fluid advancement. In the process of investigating the effect of changes in the concentration of acidic and basic solutions on the rate of fluid advancement, it observed that with increasing concentration of solutions, the length of fluid progress in the mixing channel decreases, and the highest fluid advancement occurs in microfluid with T-shaped geometry. However, the double twisted Nylon 66 yarn, grade 1880, still has the highest rate of advancement. Finally, using a T-shaped microfluid based on nylon 66 yarn, grade 1880 denier, the color change resulting from potassium iodide with copper ion reaction was used to identify the Cu2+ ion. The first color change was observed when using a copper solution with a concentration of 0.002 M, and gradually with a gradual increase in concentration, different colors are observed.   

   سوخت­هاي بيوديزل به علت خاصيت تجديدپذيري و آلايندگي كمتر امروزه در معرض توجه بسياري از كشورهاي دنيا و علي الخصوص كشورهايي كه با بحران منابع سوختي درگير هستند مي­باشد. اين سوخت ها كه از منابع متنوعي همچون روغن­هاي گياهي، چربي­هاي حيواني و جلبك ها به دست مي­آيند، با ديزل معمولي تركيب شده و در موتور خودروها مورد استفاده قرار مي­گيرند. با توجه به تنوع تركيب ديزل/بيوديزل نيازمند توسعه مدل­هايي براي اندازه­گيري خواص اين مخلوط ضروري مي­نمايد كه اين مدل مستقل از نوع بيوديزل باشند. يكي از بهترين روش­هايي كه امروزه براي توصيف روابط رياضي پيچيده و يا پارامترهايي كه داراي رابطه رياضي خاصي نمي­باشند، استفاده از شبكه­هاي عصبي مي­باشد. عدد ستان و ويسكوزيته، دو مورد از خواص بسيار مهم بيوديزل هستند كه جز شاخصه‌هاي اصلي كيفيت سوخت به شمار مي‌روند؛ بطوريكه هر چه عدد ستان بيشتر باشد، كيفيت سوخت بيشتر بوده و هر چقدر مقدار ويسكوزيته آن كمتر باشد، سوخت به سهولت در موتور خودرو جابجا شده و بازدهي آن بالاتر خواهد بود. در اين پايان­نامه با استفاده از ساختارهاي متفاوتي از شبكه­هاي عصبي شامل الگوريتم­هاي آموزش مختلف (لونبرگ ماركوات، كاهش گراديان، BFGS، گراديان مزدوج)، توابع فعال ساز گوناگون (logsig، tansig، radbas، purelin) و تعداد نورون­هاي متغير از 1 تا 20 به محاسبه مقادير ويسكوزيته سينماتيك و عدد ستان مخلوط ديزل/بيوديزل پرداخته مي­شود. در اين پايان­نامه از 6 نوع بيوديزل مختلف استفاده شده است كه خواص درصد حجمي بيوديزل، عدد ستان بيوديزل ، دماي جوش، دماي تبخير، دماي فلش، دماي ريزش، گرماي احتراق، دماي ابري شدن، ويسكوزيته سينماتيك و وزن مخصوص آن­ها در دسترس مي­باشد. براي محاسبه ويسكوزيته سينماتيك و عدد ستان مخلوط، از تركيب­هاي متنوعي از ورودي­ها (دومتغيره و سه متغيره) استفاده شد تا بهترين آن­ها به دست آيد. نتايج نشان داد كه يك شبكه عصبي با الگوريتم لونبرگ ماركوات، تابع فعال ساز purelin، تعداد نورون 7 و با دو ورودي درصد حجمي بيوديزل خالص و ويسكوزيته سينماتيك بيوديزل خالص داراي مقادير ضريب همبستگي 9957/0 و ميانگين مربعات خطاي 0054/0 بيشترين برازش را با داده­هاي آزمايشگاهي ويسكوزيته سينماتيك مخلوط دارد. همچنين با در نظر گرفتن سه متغير ورودي درصد حجمي بيوديزل، ويسكوزيته سينماتيك و وزن مخصوص بيوديزل ميزان ضريب رگرسيون برابر 9947/0 و ميانگين مربعات خطا برابر 0063/0 به دست مي­آيد كه مدل مناسبي به شمار مي­رود. نتايج محاسبه عدد ستان مخلوط نيز نشان داد كه در حالت ورودي دو متغيره (درصد حجمي بيوديزل و عدد ستان بيوديزل)، يك شبكه عصبي با الگوريتم لونبرگ ماركوات، تابع فعال ساز tansig و تعداد 10 نورون و مقدار ضريب رگرسيون 9803/0 و ميانگين مربعات خطاي 4247/0 بيشترين سازگاري را با داده­هاي آزمايشگاهي دارد. با اين حال با فرض ورودي سه متغيره (درصد حجمي بيوديزل، عدد ستان و دماي ابري شدن) و با الگوريتم آموزش لونبرگ ماركوات، تابع فعال ساز tansig و تعداد 8 نورون و مقدار ضريب رگرسيون برابر 9903/0 و ميانگين مربعات خطا برابر با 2968/0 مي­باشد كه بيانگر مدل بهتري نسبت به حالت ورودي دو متغيره مي­باشد. نتايج ساير ورودي­ها در خلال پايان­نامه آورده شده است.    كليدواژه‌ها: شبكه عصبي، مخلوط ديزل/بيوديزل، مدل سازي، پيش‌بيني خواص.   

مدل‌سازي   CFD به عنوان ابزاري قدرتمند براي بهينه‌سازي و مدل‌سازي سيستم‌هاي پيچيده است. با استفاده از مدل CFD اثر پارمترهاي مختلف بر اندازه ذرات و توزيع آن‌ها بررسي مي‌شود. ازكاربردهاي نتايج پايان‌نامه توزيع اندازه ذرات در همان مكان‌هايي كه در اندازه‌گيري‌هاي تجربي موجود در اسپري انجام شده‌است، مي‌باشد. و همچنين روشي را براي بهبود توانايي كدهاي ديناميكي سيالات محاسباتي (CFD) براي مدل‌سازي مكانيسم‌هاي اتمايزيشن مايع كه با عث كاهش هزينه و افزايش راندمان شود، ارائه مي‌دهد.حمل دارو در مباحث پزشكي و داروسازي همواره از اهميت بالايي برخوردار بوده است. به دليل خاصيت تخريب پذيري نانوذرات پليمري داروهاي حمل شده توسط اين پليمرها به طور كنترل شده‌اي در سيستم‌هاي بيولوژيكي آزاد شده   و سبب افزايش اثرگذاري دارو در بدن مي‌شوند. انتقال و جدايش دارو به شدت تحت تاثير اندازه ي نانوذرات و پلي ديسپرسيتي(توزيع اندازه ي ذرات) است تا بدين وسيله دارو درون كپسولي احاطه شود.همچنين اين پايان‌نامه در سيستم‌هاي توليد نانو ذرات با استفاده از اتمايزر و فيلم ريزان از جمله دارورساني هدفمند كه براي آن توزيع اندازه ذرات قابل كنترل باشد، كاربردي است.  هدف از اين كار ارزيابي تكنيك‌هاي مختلف براي مدل‌سازي اتمايزيشن سيستم توليد نانوذرات براي تكميل اندازه‌گيري‌هاي تجربي قبلي است. همچنين مي‌توان به طراحي روش تلفيقي جديد براي توليد اين نانوذرات با توزيع اندازه يكنواخت اشاره كرد. و همچنين روشي را براي بهبود توانايي كدهاي ديناميكي سيالات محاسباتي (CFD) براي مدل‌سازي مكانيسم‌هاي اتمايزيشن مايع ارائه مي‌دهد.نبولايزر  وسيله‌اي براي رساندن دارو به قسمت‌هاي مختلف دستگاه تنفس از طريق استنشاق مي‌باشند، اين درمان بخصوص در وضعيت‌هايي مانند  برونشيت  و  آسم  شديد بسيار مؤثر هستند و به دليل سريع بودن تأثير دارو و جلوگيري از تأثير دارو بر بافت‌هاي ديگر بدن بسيار مورد توجه مي‌باشد.نبولايزرها به دو گروه كلي مكانيكال Homemade) ، Soft mist inhaler و( Human powered nebulizer   و الكتريكال Vibrating mesh technology) ، Vibrating mesh technology و اولتراسونيك ( تقسيم بندي مي‌شوند: -  پنوماتيك (فعال شده توسط هواي فشرده): جهت رساندن ذرات نبولايز شده دارو به برونش‌ها، بايداين اجزاء به اندازه‌هاي حداقل 5 تا 10ميكرون تبديل شوند.-  تكنولوژي مش كپ (Vibrating meshtechnology): براي تأثير بر برونشيول‌ها به اندازه 2 تا 6 ميكرون كوچك شوند.اولتراسونيك (Ultrasonic wave nebulizer): درصورتيكه اين دارو به ذرات حدود نيم تا دو ميكرون تبديل شوند بر  آلوئولها  اثر خواهند گذاشت. كوچك شدن اندازه ذرات دارو بستگي به نوع دارو و جايگاه اثرآن‌ها خواهد داشت لذا از تكنولوژي‌هاي مختلف براي نبولايز استفاده مي‌شود.تئوري فيلم مايع ريزان به حركت سيال در مجاورت سطح جامد گفته مي‌شود كه در اين تئوري حركت سيال درهم بوده و انتقال جرم از سطح جامد به سيال صورت مي‌گيرد. در اين تئوري فرض مي‌شود كه تغييرات غلظت در يك لايه خيلي نازك صورت مي‌گيرد. در خارج از اين لايه غلظت ثابت است و درون اين لايه جريان آرام و انتقال از طريق نفوذ صورت مي‌گيرد. انتقال دارو از طريق نانوذرات و با استفاده از فرمولاسيون خاص، از پرطرفدارترين حوزه‌ها در نانوتكنولوژي محسوب مي‌شود. با گذر از ميكروذرات به نانوذرات (ذراتي با ابعاد 1 تا 100 نانومتر)، تغييراتي در برخي خواص فيزيكي اتفاق مي‌افتد كه افزايش نسبت سطح به حجم و ورود اندازه ذره به قلمرو اثرات كوانتومي از موارد مهم آن هستند. يكي از روش هاي معمول صورت گرفته جهت توليد نانوذرات، روش ژلاسيون يوني است. در اين روش يك برهم‌كنش الكتروستاتيكي بين گروه آمين پروتونه شده در مولكول نانوذره و يك گروه آنيوني، موجب تشكيل نانوذرات مي‌شود. در تحقيقات صورت گرفته با استفاده از روش ژلاسيون يوني، براي بررسي اندازه و مرفولوژي نانوذرات، پارامترهاي زيادي از جمله وزن مولكولي نانوذره، نسبت وزني (غلظت) نانوذره به عامل آنيوني ، PH و...مورد بررسي قرار گرفته‌است.

In this study, simulation of solar chimney thermal performance in the presence of phase change material (PCM) as thermal energy storage by computational fluid dynamics (CFD) at two thermal powers 1200 W and 800 W for melting process in closed and open heating states and freezing process in Closed and open channels were examined. In closed heating mode, in order to store energy, thermal power is applied by the PCM, and in open channel mode, the heated air is transferred to the environment by thermal evacuation. In order to perform fluid dynamics analysis, the performance of the device with PCM has been investigated using Comsol software. The solar chimney studied in this project consists of three main parts including: PCM chamber, absorber plate and air duct. According to the definition, first the thermal energy is transferred to the fluid and the adsorbent plate and consequently the PCM and also the heat input leads to an increase in the temperature of the fluid inside the duct and is converted into kinetic energy and as a result the fluid flows into the chimney. And causes heat transfer to the environment. The geometry of the solar chimney device is designed with the actual dimensions of the chimney made in the reference. In the next step a PCM system was used. These materials have been used to improve heat transfer inside the solar chimney and have been simulated by CFD. Parameters such as the velocity of the fluid entering the channel, the thermal conductivity of the absorber plate and the thermal conductivity of the PCM have a great effect on the melting time of the PCM and also the specific heat capacity and latent heat of the PCM on energy storage. It affects. The results of simulation of the process of melting the PCM showed that by applying the power of 1200 W of closed and open heating, the time required for melting is 3 hours and 10 minutes and 4 hours and 30 minutes respectively, while in the experimental study these values It is 3 hours, 4 hours and 15 minutes, respectively. Also, the freezing time in the simulation in closed and open air channel mode is 7 hours and 40 minutes, 6 hours and 30 minute   respectively, while in the experimental study, these values ??are 7 hours and 10 minutes, 6 hours and 20 minutes. The outlet temperature of the solar chimney in the simulation is 1200 W in heating mode depending on 69 °C, which is 71 °C in the experimental work. Also at 1200 W in open heating mode the output temperature in the simulation is 51 °C and this value is 49 °C in the experimental study. According to the simulated and laboratory results, it is evident that the PCM system increases the temperature of the exhaust air to heat the environment. Comparison of these results with experimental data confirms the accuracy of this analysis.   

Abstract Today, the use of solar collectors in the form of renewable energy has been considered due to limited fossil resources and high cost and environmental pollution. In the present study, the performance of the Evacuated Tube Collector was studied using computational fluid dynamics. Thus, and 0.5% as well as changing the position of the Evacuated Tube Collector in the effect of CuO, Al2O3, TiO2 and Ag nanofluids in volume percentages of 0.25 five angles between 10 , 80, equations are analyzed using the Simple algorithm and the Boussinesq are investigated. meshing was performed by Gambit software version 2.4.6 and fluid dynamic modeling was performed by Ansys Fluent 15 software. Fluid flow other places and in the upper half of the collector or the condenser pipe approximation. The results of velocity and temperature inside the collector showed that the flow velocity in the middle of the collector is higher than inside the tank is slightly weaker and in the lower half of the collector ortemperature is maximum and reaches about 370 K. The values ??of average the evaporator absorber pipe is very weak. In such a way that heat exchange is done through almost zero displacement and most of the heat transfer is done through thermal conduction. Also, in the lower half of the collector, theis below 0.1 m / s. The results of changing the angle of the collector on its temperature and velocity of flow inside the collector are a function of changes in radiation flux during the day, so that these values ??are maximum in the middle of the day and minimum during the morning and evening. The maximum speedtank in relation to increasing the angle of the vacuum tube solar collector are performance showed that the flow velocity inside the collector increased with increasing angle, so that the flow velocity at an angle of 80 degrees was twice that of an angle of 60 degrees. However, the temperature changes of the storagethe effect of CuO, Al2O3, TiO2 and Ag nanofluids on the collector performance first increasing and then decreasing, so that the increase of temperature in the angles of 10 and 80 degrees has the lowest values. It was observed that at an angle of 40 degrees between the increase in temperature is higher than the other angles and therefore this angle is the best possible. Investigation ofrespectively, TiO2 nanoparticles in volumetric percentages of 0.25 and 0.5 showed that nanoparticles have an increasing effect on tank temperature, so that for CuO nanoparticles in volume percentages of 0.25 and 0.5%, respectively, an increase of 0.43% and 0.59%, respectively. Al2O3 nanoparticles in volume percentages of 0.25 and 0.5 percent increased by 0.85 and 1.21 percent, percent increased by 0.03 and 0.07 percent, respectively, and Ag nanoparticlestherefore the best nanoparticles were selected. in Volume percentages of 0.25 and 0.5 percent increase of 1.11 and 1.52percent, respectively. The results showed that TiO2 nanoparticles had the leasteffect and Ag had the most effect on increasing the tank temperature and Keywords: Solar Collector, Numerical Method, Nanofluid,Collector Angle, Ansys Fluent   

در اين مطالعه كاتاليست نيكل-آهن بر پايه آلومينا در ريفرمينگ خشك متان در ميكرو راكتورها به منظور بررسي نحوه عملكرد كاتاليست و دستييابي به نقطه بهينه كاتاليست انجام گرفته است. 

Among the various biopolymers, chitosan, besides having the highest absorption capacity, is of great importance because it is biodegradable, pH sensitive, natural, biocompatible and non-toxic. Has mucous membranes inside the body and delivering medicinal compounds to different parts of the body. It also has anti-fungal and antibacterial effects. There are different ways to prepare chitosan nanoparticles. Ionic crosslinking is one of these methods based on ion interactions between the positive charge of chitosan amine groups and the negative charge of the polyionic groups and forms a complex and the chitosan precipitates in the form of spherical particles. Advantages of this method include non-use of organic solvents, mild reaction conditions (ambient temperature), repeatability and high stability of nanoparticles.In this study, chitosan nanoparticles were produced by using a combination of atomizer and falling film based on ion bonding between chitosan amine groups with sodium tripolyphosphate anionic group. The purpose of the design of the falling film system was to increase the contact surface of the two solutions when synthesized to form suitable and highly stable nanoparticles. The order of the experiments was that first, the hydrodynamic study of the atomizer output droplets with different flow rates from the liquid and the gas was performed and the optimum flow rates for the liquid was determined and was considered constant in all tests. In the second experiment, the size, polydispersity index (PdI) and morphology of chitosan nanoparticles produced under different parametric conditions were investigated and the optimum conditions were determined. Parametric conditions included concentration of chitosan, concentration of sodium tripolyphosphate, atomizer distance to inclined plate, air flow rate and pH of chitosan solution. The inclined surface angle was also a parameter of the problem, but after some investigation, a constant value was considered. Finally, the results showed that the system is capable of producing nanoparticles in a spherical shape with appropriate size and uniform distribution.  

   در اين پژوهش نانوذرات دي اكسيد تيتانيوم عاملدار شده با آمينو اسيد هاي هيستيدين و سرين سنتز شد و با آزمون­هاي FE-SEM[1] و FT-IR[2]   ارزيابي گرديد. سپس نانوذات سنتز شده در ساختار غشاهاي نانوفيلتراسيون پلي اتر سولفوني با درصدهاي وزني مختلف (0.1، 0.5 و 1 %) آميخته شد. غشاهاي ساخته شده با آزمون هاي با   زاويه تماسي استانيكي، SEM، AFM و درصد تخلخل مود بررسي قرار گرفت. نتايج زاويه تماس غشا نشان مي دهد ميزان آبدوستي سطح غشا با افزودن نانوذرات افزايش يافته است وكمترين ميزان زاويه تماس مربوط به غشا پلي اتر سولفون آميخته شده با نانوذرات دي اكسيد تيتانيوم عامل­دار شده با هيستدين مي باشد. تصاوير SEM و درصد تخلخل محاسبه شده نشان مي دهد كه با افزودن نانوذرات تخلخل غشا افزايش يافته، ضخامت لايه بالايي غشا كاهش يافته در حالي كه   حفره­هاي انگشتي در لايه زيرين پخن تر شده اند. نتايج AFM نشان مي دهد با افزودن هر دو نانوذره دي اكسيد تيتانيوم عاملدار شده با آمينو اسيد هاي هيستيدين و سرين سطح غشا يكنواخت تر و صاف تر شده است و پارمترهاي زبري سطح كاهش يافته است. به منظور تعيين غلظت بهينه نانوذره،   شار آب عبوري غشا، خاصيت ضد گرفتگي و ميزان پس دهي رنگ Direct red 16 در سيستم انتها بسته مورد بررسي قرار گرفت. نتايج نشان داد غشا با 0.5 درصد وزني   از هر دو نانوذره بهترين عملكرد را دارد و نانوذره دي اكسيد تيتانيوم عامل­دار شده با آمينو اسيد هيستيدين عملكرد بهتري نسبت به نانوذره دي اكسيد تيتانيوم عامل­دار شده با آمينو اسيد سرين دارد.   ميزان شار عبوري، نسبت بازيابي شار و پس دهي رنگ Direct red 16 در غشا بهينه به ترتيب است. عملكرد غشا بهينه هردو نانوذره دي اكسيد تيتانيوم عامل­دار شده با آمينو اسيد هاي سرين و هيستيدين به منظور تصفيه پساب كاخانه توليد روغن خرما بررسي شد. همچنين اثر پارامترهاي غلظت COD، فشا عملياتي و سرعت جريان خوراك نيز بر عملكرد غشا مورد بررسي قرار گرفت. شار عبوري از غشا M-0.5 براي هردو نانوذره دي اكسيد تيتانيوم عامل­دار شده با آمينو اسيد هاي سرين و هيستيدين در شرايط بهينه عملياتي (فشار 5 بار، غلظت COD = 1000 ميلي گرم بر ليتر و سرعت جريان خوراك 150 ليتر بر ساعت) به ترتيب   كيلوگرم بر مترمربع در ساعت به دست آمد در حالي كه درصد حذف COD به ترتيب 100 % و 100 % مي باشد. همچنين نسبت بازيابي شار   براي هردو نانوذره دي اكسيد تيتانيوم عامل­دار شده با آمينو اسيد هاي سرين و هيستيدين در شرايط بهينه عملياتي به ترتيب 90 % و 99.1 % بدست آمد. با توجه به نتايج بدست آمده غشا پلي اترسولفون آميخته شده با نانوذره دي اكسيد تيتانيوم عامل­دار شده با آمينو اسيد هيستيدين با غلظت 0.5 درصد وزني عملكرد بهتري نسبت به غشا پلي اتر سولفون خالص و ساير غشاهاي اصلاح شده دارد.[2] Fourier transform infrared spectroscopy

  This study experimentally investigates heat transfer inside a micro exchanger using some active smooth and coiled inserts. The obtained results were then simulated using computational fluid dynamics (CFD) techniques. A 1mm ID micro exchanger was equipped with some inserts either smooth or coiled. The length of the inserts were 6, 9, 12 cm (equal to the length of the micro exchanger) with the cross sectional radius of 0.26 mm. According to resistance of the inserts, different voltages are applied and the relevant electrical powers are transferred to working fluid. The working fluid is silicon oil warmed up contacting with the surface when flowing through the micro exchanger. Amounts of pressure and temperature were measured in inlet and outlet of the micro exchanger under different operating conditions. These operating conditions were three different flow rates 0.5, 1.5, and 2.5 ml/min and three different voltages 2, 3, and 4 V, which were applied to the micro exchanger with different inserts, as mentioned above. Four criteria employed to compare the effect of different inserts and operating conditions are performance, enhancement in efficiency, frictional losses, and thermal-hydraulic performance coefficient. In all the conditions, the data were compared to the micro exchanger equipped with the shortest smooth insert under the minimum flow rate and applied voltage. The experimental results obtained by smooth inserts demonstrated that by increasing the length of the insert the performance, enhancement in efficiency, and frictional losses were increased. Increasing the rate of thermal performance was considerably higher than frictional losses, and therefore, the thermal-hydraulic performance coefficient, as consequent of heat transfer and pressure drop, significantly increased. The relevant amount of the above mentioned coefficient for the micro exchanger equipped with the 12 cm smooth insert and 3 V applied voltage were 1.5, 2.7, ad 3.5 respectively for 0.5, 1.5, and 2.5 ml/min. In the case of coiled inserts, the thermal-hydraulic performance coefficient were significantly higher than smooth inserts due to increased frictional losses. These amounts were respectively 8.2, 22, 23.5 for 0.5, 1.5, and 2.5 ml/min. In the lowest flow rate, 0.5 ml/min, the micro exchanger equipped with the 9 cm insert demonstrated an acceptable thermal-hydraulic performance coefficient, while for higher flow rates the best performance were obtained for 6 cm insert. Under the higher flow rates, the induced turbulences lead to a better heat transfer in short distances. Increasing the length of the inserts induces additional frictional losses which lead to lower thermal-hydraulic performance coefficient. In order to figure out the heat transfer mechanism, A CFD simulation were conducted for all the relevant experimental conditions. The results were reported via different velocity and temperature vectors and contours. In addition, using the predicted amount of temperature and pressure drop in the micro exchanger, the thermal-hydraulic performance coefficients were calculated and compared to experimental data. The comparisons show a good agreement between the experimental and modeling results, the maximum amount of the error were 18.4% .   Keywords: micro exchanger, active inserts, frictional losses, thermal-hydraulic performance coefficient, CFD simulation  

  Experimental study and CFD modeling of using inserts in microtubes for heat transfer rate enhancement

Photovoltaic cell performance enhancement using hybrid system /micro channel/phase change material   cooling system

  In this study the effect of ferrite particle in magnetic field on force heat transfer enhancement is investigated. For this purpose an experimental rig has been designed. The effect of different external magnetic field is studied. The effect of reciprocate movement of magnetic field on heat transfer enhancement is studied. The results show that using this system an enhancement of between 16.35% - 36.24% are obtained. Finally, the results are expressed in terms of dimensionless numbers.

In this thesis, numerical simulation of fluid mixing has been performed for non-Newtonian flow under the effect of electric filed (Electroosmotic flow). This problem is of great importance as a frequent process in advanced and progressive technology of Lab-on-Chips and has numerous applications introduced in medical and biochemical areas. One of the major purposes of this field is to design high performance micromixers so that ideal mixing can be achieved in minimum time and energy consumption. In this study, the effects of governing parameters on mixing performance have been investigated in a flow field consisted of combined electroosmotic and pressure driven flows in presence of physical hurdles and zeta-potential heterogeneities. The simulations have been conducted for 2D geometry using finite element method by means of commercial code COMSOL Multiphysics 5.2a. Nernst-Planck equations have been used for the modeling of electric double layer (EDL) and the distribution of ions. The results indicate that several factors such as dilatant fluid behavior, adverse pressure gradient, zeta-potential heterogeneities as well as height of hurdles can have augmentative effects on the mixing performance. It is found that increasing the length of the hurdles has small effects on mixing performance while the location of the hurdles along the channel hardly changes the mixing quality. It is also seen that the effect of patches’ arrangement on the mixing is mostly depended on the magnitude of the zeta-potentials of the patches. The results showed that among the various effective parameters, the best choice for increasing the mixing quality is to increase the value of zeta-potential of the patches, because the mass flow rate passing the micromixer has no reduction and it is almost constant. This is a key characteristic because any reduction in mass flow rate is undesirable and deteriorates the performance of micromixer.

This tehsis reports the results of study on micromixing performance of three basic types of spatial shaped micromixers. New configurations of Y-T and ?- spatial shaped microchannels were designed with change in the angles of the confluence and the outlet channel to achieve the efficient micromixing. Such the micromixers offer advantages that are not attainable with the typical types of these mixers. Experimental tests were carried out in the laminar flow regime and the mixing efficiency was evaluated using Villermaux/Dushman test reaction. The geometry of the channels was cylindrical with a length of 30 mm and a diameter of 800mm. The experimental results show that the angle of outlet channel has a significant effect on the pressure drop and segregation index. In general, the results reveal that at various feed flow rates the spatial shape of channels can lead to considerable improvement in micromixing performance. In all Y-T and ?- spatial shaped microchannels, significant enhancement by increasing theconfluence angle was also seen because the fluid elements were stretched and folded in the two inlet fluid interfaces. Furthermore, the micromixing time for the more efficient geometry of three shapes of microchannels was determined based on the incorporation model, which it was in the range of 0.001–0.1s.

هدف اصلي اين مطالعه كاهش پرت هگزان در صنعت روغنكشي از دانه روغني سويا مي باشد.بدين منظور سيستم مينرال اويل كه به هدف بازگرداني بخارات متصاعد شده هگزان در محيط   و چگالش آن جهت استفاده مجدد در سيستم مي باشد مورد بازبيني و شبيه سازي قرار گرفت.تست هاي آزمايشگاهي جهت تشخيص ميزان حلال در روغن معدني ،از نوع كروماتوگرافي گازي بوده و نتايج در نرم افزار طراحي آزمايشات چهار فاكتوري -3سطحي بر پايه RSM   پياده و مورد تحليل قرار گرفتند.در اين كار چهار پارامتر موثر بر كاهش اتلاف هگزان شامل تناژ دانه ورودي ، دماي آب ورودي سرد،دماي ستون گرم و دبي سيالات تحت آزمايش مد نظر قرار داده شد.در نهايت بعد از شبيه سازي نتايج   بدست آمده مشخص گرديد كه افزايش تناژدانه و بالا نگه داشتن آن ، پايين نگه داشتن دماي آب ورودي به كندانسور سيستم ،بالا نگهداشتن دماي ستون دفع از طريق بخار زنده در يك رنج مشخص و افزايش دبي سيال جاذب در محدوده مناسب با شرايط عملياتي برج همگي عوامل مثبت در بازيابي بهتر حلال   از روغن معدني هستند.

Nowadays, in the various industries, studies on the use of magnetic water are under way. In this study, by constructing the magnetic water production device, the authors of the results on the water hardness were investigated. By applying magnetic and electromagnetic fields on water, its structure has been changed. In experiments conducted with two different channels of microchannel, the output water after the passage of filter paper for the separation of calcium carbonate has been studied and the results show that factors such as discharge flow, magnetic field intensity and electromagnetic field on the water properties It has direct effect, and less water can be gotten softer water. With magnetic water, without adding chemicals to the water, the sediments on the surfaces in contact with previously formed water are thinned and the formation of new sediment is also prevented.  

  In this study methanol production mechanism is unchanged and methanol production in micro channel has been investigated and modeled just with change in some operation conditions (temperature, pressure and …). A main difference of micro channel than other instruments is that in micro channel can be achieved industrial scale with coupling several micro channels without change in scale of channels. In other word, with adding multiple micro channels together or put them on each other can increase instrument capacity and produce product in industrial scale without change in yield. While in other common industrial instruments maybe the project fail and change yield with increasing scale from pilot to plant. In addition, small scale of reactor has advantage that energy can be delivered better and more effective. In this work, CFD modeling of micro channel for methanol production has been carried out with Gambit and Fluent in heterogeneous conditions. Methanol is produced by syngas feed and Cu/ZnO/Al2O3 coated on wall of micro channel as catalyst. In order to design experiments, has been used design expert software and CCD method. Factor considered in the design of experiments were temperature, pressure, length and radius of reactor and entrance syngas ratio. Except syngas ratio, other parameters have been investigated, quantitatively. Optimum operation conditions were pressure of 80 bar and temperature of 523 K. In these conditions has been obtained maximum methanol production

  This paper introduces design and application of a novel hybrid sun-wind-tracking system. This hybrid system employs cooling effect of wind, beside the advantages of tracking sun for enhancing power output from examined hybrid photovoltaic cell. The principal experiment focuses on comparison between dual-axes sun-tracking and hybrid sun-wind-tracking photovoltaic (PV) panels. The deductions based on the research tests confirm that the overall daily output power gain was increased by more than 49.83%, compared with that of a fixed system. Moreover, an overall increase of about 7.4% in the output power was found for the hybrid sun-wind-tracking over the two-axes sun tracking system.

Gas lift operation is one of the most common artificial lift methods that may be applied to obtain maximum production rate with minimum flowing – bottom hole pressure. The goal of this project is achieved by injecting gas to the wellbore in order to move oil to the surface.We chose gas lift in three wells in East of Baghdad field which located about (20 km) from the center of   aghdad and it extends from east – west to south – east by (100 km) length and (11 km) width.   In this study, a program has been developed using basic programming language to calculate the flowing – bottom hole pressure by using two correlations which are : modified Beggs – Brill and Aziz et ,al.   Gas and oil properties have been studied and the most accurate correlations and methods for prediction of these properties have been selected to use in the calculations. Standing correlation (1981) is use to calculate the oil density while the gas viscosity is calculated by Lee – Gonzalez – Eakin (1966).     Comparison of   the calculated and measured values for the flowing - bottom hole pressure showed that the modified Beggs – Brill give the most accurate results than Aziz .et.al method, therefore modified Beggs – Brill has been used in gas lift design calculations.   The average temperature - compressibility factor method has been used     to calculate gas pressure gradient with the depth. Then, the point of   intersection of this curve with pressure gradient curve calculated by modified Beggs – Brill method, has been used to specify the depth of injection point. Also the injection operation pressure on the surface and its effect on injection point detection for three wells, which is the most important parameter in the gas lift design process, has been studied. The positions and the distances between valves have been determined by using rules of graphical method.   The results showed that the gas injection rate for wells No.(10,11) are     (15 MMSCF/DAY) to give maximum production rate of (3430 STB/DAY) , (2970 STB/DAY) with minimum flowing – bottom hole pressure (4287 psi) , (4105 psi) ,respectively. Also the maximum injection rate for the well No.(19) is of   (7 MMSCF/DAY) with flow rate (3512 STB/DAY) and flowing – bottom hole pressure (4187 psi). current production rate for wells (10,11,19) are (2450,2100,3100) STB/DAY respectively.This study suggests exploitation of associated gas in East Baghdad oilfield to be cycled to lift oil as an artificial lift method.   The present work includes using PIPSIM software to build a model of studied vertical wells, producing from Tanumma formation, (WH1-11T, WH2-12T, WH3-19T) after choosing the suited correlation for each well. According to the statistical results, Mukherjee & Brill correlation is the best option for these wells.Gas lift design was done after studying gas lift performance-curves, which show the change of production with many parameters (gas injection rate, injection depth, and water cut). The result of this analysis is considered as a base of   gas lift design which include determining the optimum injection gas rate, the optimum injection pressure, the depth of injection and the valve technical specifications.According to the constraints (the min. allowable pressure for designing is limited by bubble pressure and maximum production by water Injection currently used in field), the required flow rate has been achieved by using gas lift. A simplified economic analysis of using two methods (gas lift & water injection) for 12 years, showed the superiority of gas lift option.   Finally, by using optimization techniques can improve the decision making process in gas allocation for continuous flow gas lift systems in East Baghdad Oilfields.