Bio: Abbas Kasaeipoor is an academic researcher from University of Isfahan. The author has contributed to research in topics: Nanofluid & Natural convection. The author has an hindex of 21, co-authored 36 publications receiving 1080 citations. Previous affiliations of Abbas Kasaeipoor include Shahrekord University & Islamic Azad University.
TL;DR: It is found that the applied magnetic field can suppress both the natural convection and the entropy generation rate, and the nanoparticles addition can be useful if a compromised magnetic field value represented by a Hartman number of 30 is applied.
Abstract: This paper investigates the entropy generation and natural convection inside a C-shaped cavity filled with CuO-water nanofluid and subjected to a uniform magnetic field. The Brownian motion effect is considered in predicting the nanofluid properties. The governing equations are solved using the finite volume method with the SIMPLE (Semi-Implicit Method for Pressure Linked Equations) algorithm. The studied parameters are the Rayleigh number (1000 ≤ Ra ≤ 15,000), Hartman number (0 ≤ Ha ≤ 45), nanofluid volume fraction (0 ≤ φ ≤ 0.06), and the cavity aspect ratio (0.1 ≤ AR ≤ 0.7). The results have shown that the nanoparticles volume fraction enhances the natural convection but undesirably increases the entropy generation rate. It is also found that the applied magnetic field can suppress both the natural convection and the entropy generation rate, where for Ra = 1000 and φ = 0.04, the percentage reductions in total entropy generation decreases from 96.27% to 48.17% for Ha = 45 compared to zero magnetic field when the aspect ratio is increased from 0.1 to 0.7. The results of performance criterion have shown that the nanoparticles addition can be useful if a compromised magnetic field value represented by a Hartman number of 30 is applied.
TL;DR: In this article, the authors presented a numerical study of natural convection heat transfer and entropy generation of water-alumina nanofluid in baffled L-shaped cavity, where the left vertical and bottom walls were placed in hot and constant Th temperature and the middle horizontal and right vertical walls were in cold and constant Tc temperature.
Abstract: This article presents a numerical study of natural convection heat transfer and entropy generation of water-alumina nanofluid in baffled L-shaped cavity. The left vertical and bottom walls are placed in hot and constant Th temperature and the middle horizontal and right vertical walls are in cold and constant Tc temperature. The other walls are insulated. The baffle's temperature is Tc and their existence in cavity has a lot of impacts on flow behavior and it could disrupt flow order. The governing equations are solved numerically with Finite Volume Method using the SIMPLER algorithm simultaneously. The convection heat transfer results show: AR (aspect ratio) increasing enhances heat transfer. With dimensional ratio increasing, nanofluid has a greater impact on Nusselt growing. By baffle length increasing nanofluid has less impact on cooling cavity, as a result heat transfer raises. The entropy generation of mentioned parameters are also investigated and discussed. Finally, with studding the e = Sm/Num (named thermal performance) the best AR and baffle length are introduced.
TL;DR: In this article, the authors present the results of a numerical study on the mixed convection of Cu-water nanofluid in a T-shaped cavity in the presence of a uniform magnetic field.
Abstract: This paper presents the results of a numerical study on the mixed convection of Cu-water nanofluid in a T-shaped cavity in the presence of a uniform magnetic field. Some sections of the bottom walls of the cavity are heated at a constant temperature and the other walls are thermally insulated. The nanofluid at a relatively low temperature enters from the bottom and exits from the top of the cavity. The governing equations are solved numerically with a finite volume approach using the SIMPLE algorithm. The effects of parameters such as Reynolds number (10 ≤ Re ≤ 400), Richardson number (0.01 ≤ Ri ≤ 10), Hartmann number (0 ≤ Ha ≤ 80), solid volume fraction (0 ≤ φ ≤ 0.06), and cavity aspect ratio (0.1 ≤ AR ≤ 0.4) on the fluid flow and the thermal performance of the cavity are studied. The results indicate that the presence of nanoparticles enhances the heat transfer except at Re = 100 and Ha < 10 as well as Re = 400 and Ha < 60, where pure water has a slightly higher heat transfer rate compared to the nanofluid. The influence of nanofluid on the heat transfer enhancement increases as AR increases. For Ri = 0.01 and 1, the maximum heat transfer rate is obtained at AR = 0.4; however, for Ri = 10, the maximum heat transfer rate occurs at AR = 0.1.
TL;DR: In this paper, the lattice Boltzmann simulation of natural convection in H-shaped cavity filled with nanofluid is performed, and entropy generation analysis and heatline visualization are employed to analyze the considered problem comprehensively.
Abstract: The lattice Boltzmann simulation of natural convection in H-shaped cavity filled with nanofluid is performed. The entropy generation analysis and heatline visualization are employed to analyze the considered problem comprehensively. The produced nanofluid is SiO2-TiO2/Water-EG (60:40) hybrid nanofluid , and the thermal conductivity and dynamic viscosity of used nanofluid are measured experimentally. To use the experimental data of thermal conductivity and dynamic viscosity, two sets of correlations based on temperature for six different solid volume fractions of 0.5, 1, 1.5, 2, 2.5 and 3 vol% are derived. The influences of different governing parameters such different aspect ratio, solid volume fractions of nanofluid and Rayleigh numbers on the fluid flow, temperature filed, average/local Nusselt number , total/local entropy generation and heatlines are presented.
TL;DR: In this article, the authors investigated the influence of nanofluid on the average Nusselt number ( Nu av ) decreases by increasing Hartmann number ( Ha ), while the effect of solid volume fraction can be neglected at Ha greater than 60.
Abstract: In the present study, the natural convection of alumina–water nanofluid in an inclined C-shaped enclosure under the magnetic field was investigated. The inside walls are at a constant cold temperature. The right walls are adiabatic, where the other walls of cavity are heated with a constant heat flux. The results are based on the cooling optimization of heat walls using nanofluid under the magnetic field for inclination angles from 0° to 90°. The governing equations are solved using finite volume formulation and the SIMPLE algorithm is used for pressure–velocity coupling. The obtained results indicate that the influence of nanofluid on the average Nusselt number ( Nu av ) decreases by increasing Hartmann number ( Ha ). The Nu av decreases by increasing nanoparticles volume fraction up to Ha of 60 at Ra = 10 5 . The effect of solid volume fraction can be neglected at Ha greater than 60. The results demonstrated that the increase in cavity aspect ratio (AR), nanoparticles volume fraction and inclination angle ( α ) values resulted in increasing of Nu av . The influence of α on the heat transfer decreases by enhancement in AR. The nanofluid does not significantly affect the heat transfer by increasing α values. The minimum Nusselt number took place at AR = 0.2 and α = 45°.
Ferdowsi University of Mashhad1, Xi'an Jiaotong University2, King Mongkut's University of Technology Thonburi3, University of Monastir4, Shahid Beheshti University5, University of Rennes6, Clarkson University7, North Carolina State University8, University of Vermont9, University of New South Wales10, Khalifa University11, Royal Society12, Quaid-i-Azam University13, King Abdulaziz University14, University of Tehran15, Babeș-Bolyai University16
TL;DR: In this paper, the authors present a review of the main computational methods for solving the transport equations associated with nanofluid flow, including finite difference, finite volume, finite element, lattice Boltzmann methods, and Lagrangian methods.
Abstract: Modeling and simulation of nanofluid flows is crucial for applications ranging from the cooling of electronic devices to solar water heating systems, particularly when compared to the high expense of experimental studies. Accurate simulation of a thermal-fluid system requires a deep understanding of the underlying physical phenomena occurring in the system. In the case of a complex nanofluid-based system, suitable simplifying approximations must be chosen to strike a balance between the nano-scale and macro-scale phenomena. Based on these choices, the computational approach – or set of approaches – to solve the mathematical model can be identified, implemented and validated. In Part I of this review (Mahian et al., 2019), we presented the details of various approaches that are used for modeling nanofluid flows, which can be classified into single-phase and two-phase approaches. Now, in Part II, the main computational methods for solving the transport equations associated with nanofluid flow are briefly summarized, including the finite difference, finite volume, finite element, lattice Boltzmann methods, and Lagrangian methods (such as dissipative particle dynamics and molecular dynamics). Next, the latest studies on 3D simulation of nanofluid flow in various regimes and configurations are reviewed. The numerical studies in the literature mostly focus on various forms of heat exchangers, such as solar collectors (flat plate and parabolic solar collectors), microchannels, car radiators, and blast furnace stave coolers along with a few other important nanofluid flow applications. Attention is given to the difference between 2D and 3D simulations, the effect of using different computational approaches on the flow and thermal performance predictions, and the influence of the selected physical model on the computational results. Finally, the knowledge gaps in this field are discussed in detail, along with some suggestions for the next steps in this field. The present review, prepared in two parts, is intended to be a comprehensive reference for researchers and practitioners interested in nanofluids and in the many applications of nanofluid flows.
TL;DR: In this paper, a review on application of nanofluids in heat exchangers has been addressed, and it can be concluded that the use of nanophotonics in most cases improves heat transfer, which reduces the volume of heat exchanger, saving energy, consequently water consumption and industrial waste.
Abstract: In this paper a brief review on application of nanofluids in heat exchangers has been addressed. One of the barriers to increase the capacity of different industries is the lack of response of heat devices in higher capacities. In addition, increasing capacity leads to an increase in pressure drop and this is one of the most important restrictions on the large industries. Conventional methods of increasing heat transfer greatly increase the pressure drop, and according to the results of previous studies, using the special nanofluids, the thermal efficiency of the heat exchanger can be increased significantly, which is one of the most important thermal devices in the industry. In this research, firstly a review of nanofluids studies and introduction of nanofluids is presented, then their simulation methods are investigated, and finally, studies on the used tubes in the heat exchangers have been investigated, and studies of the plate heat exchanger, helical heat exchanger, shell and tube heat exchanger, and double-tube heat exchanger have been examined. The enhancement of thermal and hydraulic performance of heat exchangers is very important in terms of energy conversion, and also is important in the economic recovery of systems through savings. This paper examines previous studies on heat exchangers and using of nanofluids in them. The purpose of the paper is not only to describe the previous studies, but also to understand the mechanisms of heat transfer in the field of using nanofluids in heat exchangers, and also to evaluate and compare different heat transfer techniques. Finally, it can be concluded that the nanofluids in most cases improve heat transfer, which reduce the volume of heat exchangers, saving energy, consequently water consumption and industrial waste.
TL;DR: In this article, the performance of solar energy systems is subject to the type of the working fluid that they use for solar energy conversion and transportation, and the importance, fabrication methods and characteristics of hybrid nanofluids as well as their implications on performance parameters of solar systems have been discussed.
Abstract: Solar energy is the ultimate perceived solution of incessantly proliferating energy crisis. Diverse range of solar energy conversion systems has been employed to convert solar energy into desired useful form. Performance of solar energy systems is subject to the type of the working fluid that they use for solar energy conversion and transportation. Application of hybrid nanofluids in solar energy systems as working fluid has turned out to be very gainful in terms of performance, owing to distinct thermal transportation characteristics of hybrid nanofluids. Current article has briefly reviewed the studies discoursing the performance of hybrid nanofluid based solar energy systems. Moreover, the performance of solar energy systems based on mono nanofluids has also been overviewed. Considering the importance, fabrication methods and characteristics of hybrid nanofluids as well as their implications on performance parameters of solar systems have been discussed. Reviewed studies have reported remarkable enhancement in power output and efficiency of these systems. However, there are several issues associated with hybrid nanofluids that have abstained the commercialization of binary nanofluid based systems. These issues include instability, increased friction factor, rheological issues, and increased pumping power. Subsequently, economic and ecologic gains of using binary nanofluids in solar energy systems are presented.
TL;DR: In this article, a review of the literature on the area of heat transfer improvement employing a combination of nanofluid and inserts is performed, and the progress made and current challenges for each combined system are discussed, and some conclusions and suggestions are made for future research.
Abstract: Improving heat transfer is a critical subject for energy conservation systems which directly affects economic efficiency of these systems. There are active and passive methods which can be employed to enhance the rate of heat transfer without reducing the general efficiency of the energy conservation systems. Among these methods, passive techniques are more cost-effective and reliable in comparison with active ones as they have no moving parts. To achieve further improvements in heat transfer performances, some researchers combined passive techniques. This article performs a review of the literature on the area of heat transfer improvement employing a combination of nanofluid and inserts. Inserts are baffles, twisted tape, vortex generators, and wire coil inserts. The progress made and the current challenges for each combined system are discussed, and some conclusions and suggestions are made for future research.
TL;DR: In this paper, the effects of a heat sink and the source size and location on the entropy generation, MHD natural convection flow and heat transfer in an inclined porous enclosure filled with a Cu-water nanofluid are investigated numerically.
Abstract: The effects of a heat sink and the source size and location on the entropy generation, MHD natural convection flow and heat transfer in an inclined porous enclosure filled with a Cu-water nanofluid are investigated numerically. A uniform heat source is located in a part of the bottom wall, and a part of the upper wall of the enclosure is maintained at a cooled temperature, while the remaining parts of these two walls are thermally insulated. Both the left and right walls of the enclosure are considered to be adiabatic. The thermal conductivity and the dynamic viscosity of the nanofluid are represented by different verified experimental correlations that are suitable for each type of nanoparticle. The finite difference methodology is used to solve the dimensionless partial differential equations governing the problem. A comparison with previously published works is performed, and the results show a very good agreement. The results indicate that the Nusselt number decreases via increasing the nanofluid volume fraction as well as the Hartmann number. The best location and size of the heat sink and the heat source considering the thermal performance criteria and magnetic effects are found to be D = 0.7 and B = 0.2. The entropy generation, thermal performance criteria and the natural heat transfer of the nanofluid for different sizes and locations of the heat sink and source and for various volume fractions of nanoparticles are also investigated and discussed.