http://dspace.mist.ac.bd:8080/xmlui/handle/123456789/3 2026-04-22T10:38:52Z http://dspace.mist.ac.bd:8080/xmlui/handle/123456789/1041 DEVELOPMENT OF A DIVER PROPULSION VEHICLE SIMULATOR FOR SEARCH AND RESCUE OPERATION NAZMUL HAQ, MOHAMMED Diver Propulsion Vehicle (DPV) is a self-propelled device used to facilitate divers to move freely underwater for search and rescue operations as well as for exploration purposes. DPV provides speed and a long-range to cover a wide area for various diving operations. A DPV generally consists of a pressure-resistant waterproof casing with a battery-powered electric motor that drives the propeller. It is widely used across the globe very effectively with a varying range of design and endurance capabilities. The design and fabrication of DPVs have been done in many developed countries. Indigenous design and fabrication of DPV are possible by utilizing local resources of Bangladesh. Designed prototype DPV is developed using SolidWorks, and a CFD analysis is carried out using Ansys software. After that, a DPV model is fabricated using resources from the local market. This project preliminarily focused on design, fabrication of DPV and simulated various parameters to get better results. Finally, the test and trial results and performance of the DPV are evaluated so that it can be used effectively for search and rescue operations in Bangladesh. Development of A Diver Propulsion Vehicle Simulator for Search and Rescue Operation 2023-06-01T00:00:00Z http://dspace.mist.ac.bd:8080/xmlui/handle/123456789/1038 HEAT TRANSFER PERFORMANCE OF COOLING TOWER WITH NANOFLUIDS RAHMAN, MD. HABIBUR Cooling towers are evaporative heat transfer devices in which atmospheric air cools warm water with direct contact between the air and the water by evaporating cooling of water. The main objective of this study is to analysis the cooling tower performance, with induced draft cooling tower and finding out the effect of adding nanofluids of Al Oxide (Al2O3), Zn Oxide (ZnO), and Ti Oxide (Ti2O3) with base fluid as water. This was done by establishing experimental set up supported with computer program and varying the quality of circulating fluids by adding together at different ratio. Recently large numbers of experiments have been carried out to evaluate the effect of nanofluid in enhancement of the heat transfer rate in various heat exchangers. The heat transfer enhancement using nanofluid mainly depends on type of nanoparticles, size of nanoparticles, shape of nanoparticles, and type of base fluid and concentration of nanoparticles in the base fluid. Therefore, this study deals with several experimental investigation of the thermal performance of a prototype mechanical wet cooling tower with a counter flow arrangement. Different volume concentrations ranging from 0.18 to 0.50 vol. % of stable Al Oxide (Al2O3), Zn Oxide (ZnO), and Ti Oxide (Ti2O3) nanoparticles of 80, 35, and 70 nm diameter were considered. Water was taken as a base fluid, and the experiment was carried out at 60, 70, and 80 °C, respectively, in laboratory conditions. The study revealed that an increase in the volume concentration of the nanofluids increased the cooling range, cooling efficiency, convective heat transfer coefficient, tower characteristic called number of transfer unit (NTU), and effectiveness of the cooling tower compared with water at the same mass flow rate and inlet temperature. However, increasing the volume concentration increased the viscosity of the nanofluids, leading to an increase in friction factor. From the result it has been obtained a comparative study on terms of tower characteristics (kav/L), water to air flow ratio (L/G), efficiency, range, percentage of make-up water and evaporation heat loss are presented in graphical form. The graph shows that the performance of cooling tower is affected by the type of cooling tower and the quality of circulating fluids. The graphical analysis shows the cooling tower characteristics and efficiency decreases with an increase in (L/G), the induced draft cooling tower shows better performance than natural draft cooling tower. It is revealed that at higher volume concentration of nanofluid, cooling range would increase by 29% at low flow rates which is also vi accompanied by the heat lost by water, and thereby, average increase in efficiency is 27% at temperature 80°C. This happens more significantly with Al2O3 and ZnO nanoparticles when they are added in base fluid with different ratios. For instance, for 0.18% volume concentration of ZnO, at an inlet water temperature of 66.4 °C and water/air (L/G) flow ratio of 1.93, the cooling range increased by 3.62%, cooling efficiency increased by 33.3%, and NTU increased by 50.5% compared with fresh water (FW). Prediction of thermal performance is necessary for thermo-fluid engineering applications as well as manufacturing industries. Hence, the validation of the developed mathematical model in this study has been carried out by making comparison of the measured and predicted thermal performance. This study presents an intelligent approach based on fuzzy expert system (FES) of a cooling tower. FES links between volumetric concentration (VC), mass flow rate of liquid to air ratio (L/G) and flow rate (FR) and cooling efficiency (CE) and range (CR). To validate the mathematical model, the thermal performance in terms of cooling efficiency (CE) and cooling range (CR), L/G and liquid flow rate are measured on the developed cooling tower and compared with the predicted ones. Values are obtained from experiments on an induced draft cooling tower with nanofluids in different VC of 0%, 0.06%, 0.18% and 0.30%, respectively. The efficiency of nanofluids slightly increases about 5.04–8.82% with the growth of VC related to water at the highest value of L/G. Whereas, the efficiency significantly increased about 11–50% with the increase of VC at the lowest value of L/G. FES model has been developed for the prediction of cooling efficiency and range with nanofluid in different VC. For instance, in case of CE, the mean of measured (experiment) and predicted (FES) values have been found as 15.84% and 15.90%, respectively. Similarly, for CR, the values have been found as 3.30°C and 3.28°C, respectively. The correlation coefficients of cooling efficiency and cooling range are found as 0.961, and 0.997, respectively. The mean relative error of measured and predicted values from the FES model on cooling efficiency and cooling range are found as 9.0 % and 5.87 %, respectively. For all parameters, the relative error of predicted values are found to be less than the acceptable limits of 10 %. The goodness of fit of the prediction values from the FES model on cooling efficiency and cooling range are found as 0.960 and 0.987, respectively, which are found to be close to 1.0 as projected. The results indicate that there is less variability of the measured data and predicted data vii of the counter flow induced draft cooling tower with water and with nanofluids in different volume concentration. It also indicates that the predicted data over the measured data has a good agreement and thus substantiates the validity of the mathematical model. In this study, according to assessment principles of predicted performance of the developed fuzzy expert system based intelligent model has been found to be valid. It is an innovative adaption leading to technological capacity building which has a remarkable contribution to enhance the machine life, better-efficient outcome and friendly to the aquatic and environmental system. At first, the author expresses his heartiest thanks to the Almighty Allah for giving the patience and potentiality to complete the thesis work. I also express my appreciation to all the people who have given their hearts whelming full support in preparing and completing the study. I am highly pleased to express my sincere and profound gratitude to my supervisor Dr. Mohammad Ali, Professor, Department of Mechanical Engineering, Bangladesh University of Engineering & Technology (BUET), Dhaka, Bangladesh for providing me the opportunity to conduct research on nanofluids for cooling tower. I wish to express my deepest thanks to him for his continuous with patience guidance, suggestions, inspiring advice, constructive suggestions with enthusiastic supervision and wholehearted help throughout the course of the work. I am also thankful to Lt Col Md. Altab Hossain, PhD, Associate Professor, Dept of Nuclear Science and Engineering (NSE), Military Institute of Science and Technology (MIST), Dhaka for his continuous guidance to shape my research work. I am also grateful to Head and all Faculty Members, Dept of Mechanical Engineering for their dedicated and relentless support both for literature and experimental work. I would also express my deepest gratitude to my wife, my beloved sons and other family members for their support and encouragement. Finally, I am grateful to almighty Allah for enabling me to complete the thesis. 2025-07-01T00:00:00Z http://dspace.mist.ac.bd:8080/xmlui/handle/123456789/820 FABRICATION AND PERFORMANCE EVALUATION OF LOW COST HIGH IMPACT RESISTANT COMPOSITE RAHMAN, MD. ANISUR In this thesis low cost composite laminates were fabricated and their effectiveness against high impact was assessed. Glass fiber was used as the fiber and epoxy resin as the binder to create composite laminates. For enhanced binding properties, hardener and 6% cobalt were additionally included with the binder. The laminates vary in terms of layer count, glass fiber type (woven or matt), and curing time. For better comparison between same type of laminates, a few more variables, including the percentage of hardener, the quantity of matrix, and the curing time, were held constant. The mechanical properties were measured giving the Impact test more importance. The mechanical property tests such as the tensile test, compression test, bending test, Charpy impact test, Izod test, and free fall impact tests were done according to the different standardized test method. A laminate with greater performance was found after comparing all the attributes. The production costs were successfully reduced by the thesis because all the materials were readily available and locally manufactured with simple setups. The thesis successfully suggested a possible low-cost production setup for high impact resistant materials. The author firstly thanks Almighty Allah for His relentless blessings to complete this thesis work. The author would like to thank Professor Dr. Afsar Ali, who oversaw his thesis, for his advice, support, and assistance with this study work. The author would like to thank his co-supervisor, Prof. Dr. Enamul Hoque, for his consistent oversight, passionate observations, and direction throughout the thesis. The department's Dean, Brig Gen Md Humayun Kabir Bhuiyan, psc, whose guidance and support allowed the author to labor tirelessly and introduce new ideas, is also noteworthy. The author would also like to recognize the efforts of the lab staff, in particular Sub Asst Engr Mr. Md. Raju Ahmed and Sub Asst Engr Mr. Dibakar Tarafdar, who assisted with the setup and execution of experiments for the research work. Last but not the least, the author would like to express his utmost gratitude to his family members who has been patient and supportive all through this journey. 2023-03-01T00:00:00Z http://dspace.mist.ac.bd:8080/xmlui/handle/123456789/790 ANALYSIS OF MAGNETIC FIELD EFFECT ON PULSATING BLOOD FLOW IN ARTERIES OISHE, SADIA NOON Cardiovascular diseases including strokes, heart attacks, Stenosis, and atherosclerosis are considered the leading cause of death over the globe. The aorta, coronary, carotid, and femoral arteries are the most commonly impacted arteries. It's a crucial field of study for blood flow behavior. For many years, researchers have experimented with various numerical strategies to entice clinicians to trust their colorful contours. In recent, the impact of magnetic fields on blood flow is one of the developing approaches to treating different types of diseases. However, the efficiency of MHD capture is still unclear, and there is less systematic strategy to understand the flow behavior of blood. In this study, a simulationbased three-dimensional human aorta (brachiocephalic trunk, left subclavian, and left carotid) with transient conditions is analyzed to predict changes in blood flow distribution and flow patterns under with and without magnetic field conditions. Blood is modeled as non-Newtonian fluids along with plasma. VOF modeling for multiphase flow is used to mix RBC and plasma to predict the pulsating condition for the flow. Moreover, 1 Tesla magnetic field is applied to the selected section of the aorta. For simulation purposes, ANSYS Fluent software is used to identify the values for velocity, pressure, and wall shear force to understand the flow behavior of blood. The result shows that velocity, pressure, and wall shear stress are affected by exposure to MHD. By applying MHD, due to the freezing effect, the flow velocity slows down by about .035% while pressure increases by 9%, wall shear stress increases by 1.46% as well as mass flow. All praise be to Allah, the Cherisher and Sustainer of the worlds for His kindness and blessings for allowing me to do this colossal work and finally materialize it. The author expresses her deepest gratitude and profound indebtedness to her supervisor, Professor Dr. Dipak Kanti Das, Department of Mechanical Engineering, MIST, Dhaka, for his continuous supervision, valuable opinions, and motivation for research work all through the time. His regular support and direction made this research work possible and fruitful at every stage. The author is also thankful to Brig Gen Md Humayun Kabir Bhuiyan, psc, Dean, Department of Mechanical Engineering, MIST for his encouragement throughout the whole course. Special gratitude to Brig Gen Md. Omar Faruque, afwc, psc, Head, Department of Mechanical Engineering, MIST for his guidance at every step is duly acknowledged. The author would also like to thank Professor Dr. R. G. M Hasan for supporting me academically and personally and Professor Dr. A.B.M. Toufique Hasan for his valuable guidance and thanks to all Department of Mechanical Engineering, MIST for their cooperation in the successful fulfillment of the work. Finally, the author would like to express sincere thanks to all the beautiful people who stayed beside them when truly needed their support for the successful completion of this work. 2022-04-01T00:00:00Z