Author: Ass.Prof.Dr.Wajeeh Kamal Hasan

Numerical Investigation of Nanofluid in a Rectangular Microchannel Heat Sink

ABSTRACT: The heat transfer in a 3-D rectangular microchannel heat sink (MCHS) for single phase liquid flow using nanofluids is numerically investigated for laminar flow )Re = 60-700). In the present work, the performance of microchannel using CuO/H2O nanofluid as a coolant with different volume concentrations ranged from 0 % to 5% is examined. The partial governing equations of fluid flow and heat are solved using ANSYS fluent 12.0 based on finite volume method. The evaluated microchannel performance was shown in terms of temperature and velocity contours, average Nusselt number and pressure drop. The thermo-physical properties of nanofluid are evaluated to study its effect on the flow and heat transfer at a reference bulk temperature. A Constant heat flux of 100W/cm2 will be provided to the bottom side of highly conductive silicon substrate. The present CFD calculated wall temperature and friction factor values were associated with the analytical data and good agreement is detected. The results revealed that the nanofluids aid to improve the coefficient of heat transfer by 11% when CuO/H2O nanofluid was used. The effect of the concentration of CuO nanofluid has been discussed with Reynolds number value and with the velocity of fluid. Furthermore, plots and calculations for the heat transfer coefficients and the average Nusselt number were carried out. https://jmerd.net/Paper/Vol.43,No.6(2020)/404-417.pdf

Two-way fluid-structure interaction study of twisted tape insert in a circular tube having integral fins with nanofluid

This work deals with fluid-structure interaction (FSI), one of the emerging areas of numerical simulation and calculation. This research shows a numerical study investigating heat transfer enhancement and fluid-structure interaction in a circular finned tube by using alumina nanofluid as a working fluid with a typical twisted tape that has a twisting ratio of 1.85. The studied nanofluid volumes of fraction are φ=0, 3, 5 % under conditions of laminar and turbulent flow. The solution for such problems is based on the relations of continuum mechanics and is mostly done with numerical methods. FSI occurs when the flow of fluid influences the properties of a structure or vice versa. It is a computational challenge to deal with such problems due to complexity in defining the geometries, nature of the interaction between a fluid and solid, intricate physics of fluids and requirements of computational resources. CFD investigations were made based on the numerical finite volume techniques to solve the governing three-dimensional partial differential equations to get the influence of inserted twisted tape and concentration of nanofluid on heat transfer enhancement, friction loss, average Nusselt number, velocity profile, thermal performance factor characteristics, and two-way interaction in a circular tube at laminar and turbulent flow. The governing continuity, momentum and energy transfer equations are solved using Ansys Fluent and Transient Structural. The simulation results show that the deformations of twoway coupling fluctuate from side to side, with 0.004 mm, as maximum amplitude, located at the typical twisted tape center. Heat transfer dissipation improved by adding fins and as Reynolds numbers increase the heat transfer behavior increases. https://doi.org/10.15587/1729-4061.2021.234125

CFD Evaluation of Air Conditioning on the Distribution and Dispersion of COVID-19 Virus in a Room

With the beginning of 2020, the Corona virus pandemic began, which negatively affected all of humanity, as medical and engineering research began to solve many problems faced by society during the era of the virus. Those who are exposed to this situation are among the medical staff responsible for treating and quarantining patients with the Corona virus. It has become the responsibility of engineers to develop solutions to the ventilation problem in order to limit the spread of this virus. Where the aim of this research paper was to study the effect of distance between patient and nurse and the effect of ventilation on the spread of the Corona virus. where a simulation model was created a room with real and 3D dimensions was studied with a patient lying down and the nurse treating him next to him. Where the room contains an air conditioner, two outlets for the airflow and an opening for the patient’s mouth to simulate the exit of carbon dioxide gas from his mouth. Where the different and high speeds were studied to find out their effect on the spread of the virus abroad and its disposal. The result proves the best flow velocity of the ventilation system is 20 m/s, which led to a large limitation of the waiting for the Corona virus. The best place for the patient and the airway in the room should not be in the same airway, and the best place is between them. where these results serve as a reference for the engineering of medical rooms in terms of the effect of ventilation and distance of the pathogen on the spread of the Corona virus. https://doi.org/10.18280/ijht.400233

IDENTIFYING THE EFFECT OF CHANNEL WALL RIPPLE HEIGHT ON MULTIPHASE FLOW

With the development of simulation technology and the ability to obtain accurate numerical results, as well as with the development of information technology, software that can solve numerical problems has become necessary to see physical changes that cannot be seen by the human eye. Multiphase stream field is settled utilizing the volume of fluid (VOF) method, and the flow equations are assessed and addressed mathematically by the notable limited volume approach. As a multiphase framework without mass exchange, air/water stream is considered. For practically all cases considered in this review, the heat transfer coefficient is higher. In any case, a critical punishment pressure drop was observed especially for high mass courses through undulating channels. A wavy channel with a variable wave height was simulated to see the variables of the flow process for multi-phase materials with a square cross-section, where different speeds were used for the inlet duct for air, water and steam. The results proved that the increase in the height of the channel wall wave works to obstruct the flow and thus increases the time required for the fluid to reach the exit area. The value of time required for steam and air to reach the exit area at the channel wall wave height of 25 mm and the flow velocity of 0.1 m/s was 6.01 s, which is the longest time it took for the fluid to reach the exit area compared to other cases. The pressure value reflects the amount of turbulence in the flow process, and it’s crucial for thermal improvements based on flow turbulence. The entrance flow velocity is 0.1 m/s and the wall wave height is 25 mm at a time of 2 s, when the pressure reaches 873.7 Pa doi: https://doi.org/10.15587/1729-4061.2022.263587

Numerical Implementation of Direct and Reverse Flow for Plate Heat Exchanger

One of the best solutions for the heat exchange is the plate heat exchangers, which are characterized by high thermal efficiency. Where in this paper work has been done on a plate heat exchanger with dimensions appropriate to its practical application and changing the fluid exit areas to increase the surface area of exchange. And the use of more than one class to see the improvements and changes that can be analyzed and benefited from the first part represents the heat exchanger with a direct direction and the change in the number of plates. Where two sets of models were designed, the first representing the change in the number of plates, where 10, 20 and 30 plates were used to irrigate the real rate of increasing the number of plates. As for the second part, it represents the heat exchanger with a reverse path and compare them with each other. The result show that when increasing the number of plates in the plate heat exchanger, it increases the transfer area and thus increases the value of the transferred heat energy. In the case where the best transfer of heat energy is compared to 20 and 10 blades, where the exit temperature reached 308.1 K, it is noticing an increase in the transfer of thermal energy. https://doi.org/10.18280/mmep.100215  

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