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Mahmud H. Ali^a,* , Rawand E. Jalal^a
Frontiers in Heat and Mass Transfer, Vol.15, pp. 1-14, 2020, DOI:10.5098/hmt.15.27
Abstract In this work, natural convection in an adiabatic enclosure with openings induced by two isothermal hot cylinders is approached numerically. The study covers five different configurations of the enclosure as the number and locations of the inlet and outlet ports are varied for Rayleigh number (Ra) between 10⁴ and 10⁶ . Additionally, the study also analyzes the effects of varying the horizontal distance (S) between the cylinders along with their vertical locations () for dimensionless values of 0.4 to 0.3 and -0.2 to 0.2, respectively, at a constant Ra of 10⁶ . The outcomes show that the… More >

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N. Vijaya^a,*, S. M. Arifuzzaman^b, N. Raghavendra Sai^c, Ch. Manikya Rao^d
Frontiers in Heat and Mass Transfer, Vol.15, pp. 1-9, 2020, DOI:10.5098/hmt.15.26
Abstract The upfront intension of this study is to explore the advances in electrically conducting Casson fluid induced due to a porous elongated surface taking Arrhenius activation energy, viscous dissipation and joule heating into account. Uniform magnetic and electric fields are imposed on the given flow. Variables of similarity are induced to transmute partial differential equations into dimensionless equations and resolved numerically by elegant method bvp4c. To scrutinize the behavior of critical parameters on flow configurations graphs and table are portrayed. From graphical moments, it is analyzed that velocity of the liquid diminish for advanced More >

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Daniel Yabrudy Mercado^a,*, Juan Fajardo Cuadro^a, Bienvenido Sarria López^b, Camilo Cardona Agudelo^b
Frontiers in Heat and Mass Transfer, Vol.15, pp. 1-12, 2020, DOI:10.5098/hmt.15.25
Abstract This paper presents the efficiency-centered maintenance method to plan the maintenance intervention of the heat exchangers of a preheat train, taking into account the economic-energy improvement and maintenance cost. An appropriate cleaning schedule is needed to preserve the key performance parameters (KPPs) throughout the operation, if possible, nearest to the design values. The results of this work show that it is possible to schedule maintenance activities based on KPPs such as effectiveness and determine the time of execution and the type of maintenance that is most cost-efficient, without affecting and complementing the criteria for maintenance More >

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361

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Alaa K. Khamis^a , Allal Bakali^a, A. A. El-Bary^b,c,*, Haitham M. Atef^d
Frontiers in Heat and Mass Transfer, Vol.15, pp. 1-6, 2020, DOI:10.5098/hmt.15.24
Abstract In this paper the effect of the magnetic field and Seebeck parameter was investigated. Modified Ohm's law that includes effects of the temperature gradient (Seebeck effect More >

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371

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N. Vijaya^a,*, Sunil Babu G^b , Vellanki Lakshmi N^c
Frontiers in Heat and Mass Transfer, Vol.15, pp. 1-8, 2020, DOI:10.5098/hmt.15.23
Abstract Present investigation aims at scrutinizing the properties of heat and mass transfer phenomena of liquid thin film of Casson Nano fluid over elongated sheet under the influence of thermophorosis and Brownian motion. Casson Nano particle effect on thermophorotic force and on Brownian force is studied. Variables of similarity were induced to transmute partial differential equations into dimensionless equations and are resolved numerically by elegant method bvp 4c. Thin film thickness is calculated using MATHEMATICA for different values of critical parameters. Velocity profiles diminishes for higher values of Casson parameter and magnetic field parameter. The temperature More >

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363

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Rongge Xiao^a,*, Yanwei Zhang^a , Xu Gao^b , Hongping Yu^c , Wangying Wei^a
Frontiers in Heat and Mass Transfer, Vol.15, pp. 1-8, 2020, DOI:10.5098/hmt.15.22
Abstract In order to improve DMR (double mixed refrigerant) liquefaction process and reduce operation cost of natural gas liquefaction plant, a four-stage DMR process optimization simulation calculation model was established through Aspen Hysys v8.4 and the purpose of the optimization model is achieved by using the segmented compression process in this paper. The minimum energy consumption and the highest exergy efficiency were used as the objective functions. By using the optimizer in HYSYS, the process parameters and ingredient proportion of the mixed refrigerant in the fourstage DMR process was optimized, and the best process parameters and More >

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380

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Firas Aziz Ali^a,*, Adnan M. Alsaffawi^b , Karam Hashim Mohammed^a
Frontiers in Heat and Mass Transfer, Vol.15, pp. 1-7, 2020, DOI:10.5098/hmt.15.21
Abstract The augmentation of the heat transfer in heat exchangers is one of the methods to increase efficiency of the system. The double tube heat exchanger is selected to many suitable techniques of heat transfer enhancement. In this study; the friction factor and heat transfer coefficient of double tube is evaluated experimentally. The Al₂O₃ nanoparticles dispersed in ethylene glycol (EG) with a diameter 50 nm and the weight concentration (0.1%, 0.3%, 0.5%, 0.7%, 1%) has been utilized. Then the effect of parallel current and counter current with different ranges of Reynolds number (10,000 to 30,000) on the… More >

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345

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N. Govindaraj, A. K. Singh, Pankaj Shukla
Frontiers in Heat and Mass Transfer, Vol.15, pp. 1-8, 2020, DOI:10.5098/hmt.15.20
Abstract A numerical study of fluid flow over stretching sheet with temperature dependent properties has been performed induced by mixed convection. The significant variation of the Prandtl number and viscosity in the temperature is observed [see table 1]. Viscosity and Prandtl number are vary in inverse of the linear function. The physical problem modeled in the mathematical equations in dimension form, which is converted to the non-dimensional equations by applying similarity transformations and suitable boundary conditions. The mathematical modelling problem is transformed PDE’s are numerically solved using Quasilinearization technique and FDM. The current numerical data has… More >

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377

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Yu Chen^a , Shen Du^a, Dong Li^a, Yang Gao^b, Ya-Ling He^a,*
Frontiers in Heat and Mass Transfer, Vol.15, pp. 1-13, 2020, DOI:10.5098/hmt.15.19
Abstract Non-uniform heating and vapor blockage deteriorate the effectiveness of transpiration cooling, and an optimization method by using porous media with a gradually-changed structure is proposed. The numerical tool based on a two-phase mixture model and local thermal non-equilibrium assumption considering variable properties of coolant is applied. Porous media with linearly-changed porosity or particle diameter is analyzed. The transient results presented that the structure of gradually-changed porosity (or particle diameter) with appropriate parameters can delay the heat transfer deterioration. And it is confirmed that the present theoretical model is an effective tool for optimization design of More >

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429

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Revathi Gadamsetty^a,*, Venkata Subrahmanyam Sajja^b , P. Sudam Sekhar^c, Dhaneshwar Prasad^d,†
Frontiers in Heat and Mass Transfer, Vol.15, pp. 1-7, 2020, DOI:10.5098/hmt.15.18
Abstract Hydrodynamic lubrication characteristics of asymmetric rollers lubricated by non-Newtonian incompressible Bingham plastic fluid are analyzed in this work. It narrates the qualitative research with the rigid system in which the viscosity of the particular non-Newtonian Bingham plastic substance is considered to become the function of hydrodynamic pressure. The equations considered in this work like equation of motion along with continuity and energy equations are solved numerically using MATLAB after particular analytical steps. Resulting from this particular work, it is identified that there is some notable change in temperatures, pressure, load and traction forces with Newtonian More >

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371

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Misbahudin Alhanif, Gelbert Jethro Sanyoto, Widayat Widayat^*
Frontiers in Heat and Mass Transfer, Vol.15, pp. 1-6, 2020, DOI:10.5098/hmt.15.17
Abstract Development of sulfuric acid production method has taken us to commercial use of contact process in most industries. However, most plants still utilize coolers and steam generators to divert the excess heat. This method of energy recovery is inefficient, thus, this study attempts to redesign commercial heat exchanger network for better efficiency and lower cost. Process integration using composite curve, cascade diagram, heat exchanger network alternatives, completed with improved plant flow diagram are successfully calculated and analyzed by HINT software. Total energy saving can reach up to 74.70% and this results in total cost saving More >

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354

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Wakana Hiratsuka^a , Takashi Fukue^b,*, Hidemi Shirakawa^c, Katsuyuki Nakayama^d, Yasushi Koito^e
Frontiers in Heat and Mass Transfer, Vol.15, pp. 1-8, 2020, DOI:10.5098/hmt.15.16
Abstract This paper describes a possibility of heat transfer enhancement in a mm-scale flow channel by using a combination of some projections and pulsating flow. The objective of this research is to develop a novel heat exchanger for miniaturized productions such as high-density packaging electronic equipment by applying pulsating flow to enhance heat transfer while inhibiting an increase of pressure drop. In order to evaluate the possibility of applying pulsating flow to miniature water channels, a three-dimensional flow and heat transfer analysis was performed. Heat transfer performance of a combination of pulsating water flow and a More >

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388

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Teng Huang^a,* , Xuefang Li ^a,† , Lin Cheng^b,‡
Frontiers in Heat and Mass Transfer, Vol.15, pp. 1-8, 2020, DOI:10.5098/hmt.15.15
Abstract As a non-flammable, non-toxic refrigerant, supercritical CO₂ (ScCO₂) has been increasingly used for heat transfer applications. In this study, the ScCO₂ flow and heat transfer in a set of full-size three-dimensional serpentine tubes were modeled with different inner diameters and tube pitches. The standard k-epsilon model was used for the turbulence modeling. The results show the effect of the different tube inner diameters and tube pitches on the flow and heat transfer of ScCO₂ for a given flow flux or inlet Reynolds number. The heat transfer coefficient decreases as both the tube pitch and the inner diameter… More >

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351

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Muhammad Nazim Tufail^a , Musharafa Saleem^a,b,*, Qasim Ali Chaudhry^b,†
Frontiers in Heat and Mass Transfer, Vol.15, pp. 1-10, 2020, DOI:10.5098/hmt.15.14
Abstract This methodology presented the unsteady three-dimensional laminar flow since Hall effects inducing the cross flow in z-axis. The boundary layer and the low magnetic Reynolds number approximations are used to simplify the system of equations derived from the constitutive laws. The upper-convected Maxwell (UCM) fluid model used for Hall effects with unsteady heat transfer, which passed through the infinite stretching sheet. This flow model has intensified with the effects of magnetohydrodynamic (MHD), thermal radiation and heat generation-absorption. Here, we selected the two-parameter Lie scaling transformations to convert the highly non-linear partial differential equations (PDEs) to More >

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311

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Amnart Boonloi^a, Withada Jedsadaratanachai^b,*
Frontiers in Heat and Mass Transfer, Vol.15, pp. 1-15, 2020, DOI:10.5098/hmt.15.13
Abstract Simulated examinations on convective heat transfer and flow topology in a square duct heat exchanger placed with wavy thin rib (WTR) are presented. The influences of WTR heights, pitch distances and flow directions on flow and heat transfer characteristics are investigated for the laminar flow regime at the inlet condition (Re = 100 – 2000). The finite volume method (SIMPLE algorithm) is picked to analyze the numerical problem. The numerical validations; grid independence and verification of the smooth duct, are presented. The simulated results of the heat exchanger duct placed with WTR are reported in More >

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Yogesh Jaluria^a,*, Arvindh Sunder^a, Jingru Z. Benner^b
Frontiers in Heat and Mass Transfer, Vol.15, pp. 1-12, 2020, DOI:10.5098/hmt.15.12
Abstract Data centers are of crucial importance today in the storage and retrieval of large amounts of data. Most organizations and firms, ranging from banks and online retailers to government departments and internet companies, use data centers to store information that can be recovered efficiently and rapidly. As the deployment of data centers has increased, along with their capacity for data storage, the demands on thermal management have also increased. It is necessary to remove the energy dissipated by the electronic circuitry since the temperature of the components must not rise beyond acceptable levels that could… More >

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376

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Zhipeng Tang^a, Yongbin Zhang^b,*
Frontiers in Heat and Mass Transfer, Vol.15, pp. 1-6, 2020, DOI:10.5098/hmt.15.11
Abstract The mass flow rate through a micro/nano channel is calculated by a multiscale analysis when the thickness of the adsorbed layer on the channel wall is comparable to the channel height and the interfacial slippage on the adsorbed layer-wall surface interface occurs or not. The calculation is compared with that from conventional continuum flow theory. It is found that when the ratio More >

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Pengda Li, Chao Xu, Zhirong Liao^* , Xing Ju, Feng Ye
Frontiers in Heat and Mass Transfer, Vol.15, pp. 1-10, 2020, DOI:10.5098/hmt.15.10
Abstract This study numerically investigates the charging and discharging processes of a three-stages cascaded latent heat thermal energy storage unit using three molten salts as the phase change materials (PCMs). Each stage of the unit is a vertical shell-and-tube heat exchanger, whose shell side is filled with the PCM and air. The liquid fractions, temperatures, and accumulated thermal energy of the PCMs during the fully charging and discharging processes, as well as the effects of the HTF inlet temperature, are analyzed. The results show that lower melting temperature of the PCM causes faster charging rate and More >

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404

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Weiwei Zhang, Linghong Tang^*
Frontiers in Heat and Mass Transfer, Vol.15, pp. 1-7, 2020, DOI:10.5098/hmt.15.9
Abstract Air-side thermal and hydraulic performance of the finned flat-tube heat exchanger with single row is experimentally investigated. The correlations of the thermal and hydraulic performance are developed based on the experimental data. The effects of various fin geometrical parameters on the thermal and hydraulic performance are investigated by a numerical method, and the influence of various parameters is analyzed in detail. Results show that heat transfer performance and pressure drop decrease with the increasing fin pitch, and heat transfer performance increases with the increase of fin length and fin height accompanying with the increase of More >

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K.S. Balamurugan^a,*, N. Udaya Bhaskara Varma^b, J.L. Ramaprasad^c
Frontiers in Heat and Mass Transfer, Vol.15, pp. 1-7, 2020, DOI:10.5098/hmt.15.8
Abstract In this paper the entropy generation and temperature gradient heat source effects on MHD couette flow with permeable base in the presence of thermal radiation, viscous and joule's dissipation is studied. An exact solution of governing equations has been attained in closed form. The influences of several parameters on the velocity and temperature profiles and entropy generation are analyzed through graphs. Bejan number for different values have been calculated and displayed pictorially. The skin friction coefficient and Nusselt number at channel walls are derived and discussed their behaviour through tables. The entropy generation increases with More >

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S. Ravi Teja^a , Chellapilla V. K. N. S. N. Moorthy^b,*, S. Jayakumar^c , Ayyagari Kiran Kumar^d , V. Srinivas^c,*
Frontiers in Heat and Mass Transfer, Vol.15, pp. 1-9, 2020, DOI:10.5098/hmt.15.7
Abstract This article is a summary of research involving the evaluation of the thermo-physical properties of Mono-ethylene - glycol-based solar thermic fluids oxidized multiwalled carbon nanotubes. Nanofluids were prepared with Mono-ethylene glycol and water as base fluids in 100:0, 90:10 and 80:20 ratios. These base fluids of three categories were dispersed with purified and oxidized multiwalled carbon nanotubes (MWCNTs) in the weight fractions of 0.125, 0.25 and 0.5 percentages. The variation in zeta potential is studied to examine the dispersion stability during 2 months. Thermal conductivity and dynamic viscosity were measured by hot disk method and… More >

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Isam Mejbel Abed, Farooq H. Ali^* , Shaymaa Abdul Munem Sahib
Frontiers in Heat and Mass Transfer, Vol.15, pp. 1-9, 2020, DOI:10.5098/hmt.15.6
Abstract Forced and mixed convection in 2-D, steady state, laminar flow and heat transfer around sinusoidal corrugated circular cylinder are numerically studied. Finite Element of Galerkin approach is used to analyze continuity, momentum and energy equation at Reynolds number (Re = 01, 45, 100, 200), Richardson Number (Ri=0, 1, 2), corrugation number (G = ꚙ, 3, 4, 5, 10), amplitude values (λ= 0.1, 0.2, 0.3 and 0.6) for Prandtl number (Pr = 0.71). Results show the variation of corrugation number G and amplitude value λ have important effect on the streamline , isothermal lines, local and More >

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Rabha Khatyr^*, Jaafar Khalid Naciri
Frontiers in Heat and Mass Transfer, Vol.15, pp. 1-11, 2020, DOI:10.5098/hmt.15.5
Abstract The present study focuses on the effects of viscous dissipation and axial heat conduction on the asymptotic behavior of the laminar forced convection in a circular duct for a Herschel-Bulkley fluid with variable wall heat flux. Analytical asymptotic solutions are presented for the case of axial variations of the wall heat flux, with finite non-vanishing values at infinity along the flow direction. The asymptotic bulk and mixing Nusselt numbers and the asymptotic bulk and mixing temperature distributions are evaluated analytically in the case of axially variable wall heat flux for which polynomial and logarithmic functions More >

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Fuyong Su^a,* , Guozhi Zhang^b, Guojun Chen^c
Frontiers in Heat and Mass Transfer, Vol.15, pp. 1-5, 2020, DOI:10.5098/hmt.15.4
Abstract The iron and steel industry produces a large number of low-grade waste heat resources, which are not fully utilized. In addition, the iron and steel industry consumes a lot of water. This paper presents a method of utilizing waste heat of blast furnace slag flushing water for seawater desalination. After the flash process, heat exchange process and heat repair process, the blast furnace slag water was converted into steam which is 70 °C, which provided a heat source for MED (Multi-effect Desalination). This utilization method of waste heat was verified by thermodynamics and production data. More >

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Xiaoyong Gu^*, Guohe Jiang, Yang Wo, Biwen Chen
Frontiers in Heat and Mass Transfer, Vol.15, pp. 1-8, 2020, DOI:10.5098/hmt.15.3
Abstract The heat transfer characteristics of propylene glycol-water (PG-W) mixture with different concentrations in shell side of spiral wound heat exchanger (SWHE) with different geometric parameters were studied numerically. Experiment was carried out and the average difference between the simulated results and the experimental results was 5.3%. The simulation results show that heat transfer coefficient increases with the increase of center core diameter and longitudinal spacing of tubes, but decreases with the increase of tube outer diameter. The center core diameter and tube outer diameter have greater effects on heat transfer performances at higher concentration. Economic More >

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Manfred Groll
Frontiers in Heat and Mass Transfer, Vol.15, pp. 1-7, 2020, DOI:10.5098/hmt.15.2
Abstract Each individual human being, groups of individuals, whole nations depend on the availability of energy for their survival. Without energy, no civilization can develop and sustain. In our globalised civilization, hundreds of millions of people cannot satisfy their needs for energy, be it in the elementary form of food, (clean) water for drinking, cooking and irrigation, (clean) air and (clean) soil for production of crops, or be it in energy required for heating/refrigeration, light, radio, TV, etc. Modern industrialized societies with their huge energy demand for industry, the transportation sector and for building up or… More >

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408

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Fangzhou Wang^a,* , Gennifer A. Riley^b, Munonyedi Egbo^c, Melanie M. Derby^b, Gisuk Hwang^c, Xianglin Li^a,†
Frontiers in Heat and Mass Transfer, Vol.15, pp. 1-8, 2020, DOI:10.5098/hmt.15.1
Abstract This study conducts pore-scale simulations and experiments to estimate the permeability of two different types of porous materials: metal foams and sintered copper particles with porosities of approximately 0.9 and 0.4, respectively. The integration of micro X-ray computed tomography with pore-scale computational fluid dynamics simulations develops a unique tool to capture the pore-scale geometry of porous media and accurately predict non-isotropic permeability of porous media. The pore-scale simulation not only results in improved prediction accuracy but also has the capability to capture non-isotropic properties of heterogeneous materials, which is a huge challenge for empirical correlations,… More >

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