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Yasushi Koito^a,*
Frontiers in Heat and Mass Transfer, Vol.16, pp. 1-7, 2021, DOI:10.5098/hmt.16.1
Abstract For ultra-thin heat pipes, a centered wick structure is often used. In this study, a numerical analysis is performed on an ultra-thin heat pipe in which the wick structure’s position has deviated from the center. A 3D heat pipe model, developed by the author in a previous study, is extended, and numerical calculations are conducted to determine any differences in performance because of an off-center wick. The major findings are as follows: (1) a completely centered wick structure is recommended for optimum performance; (2) accurate central positioning of the wick structure is important in the fabrication process of ultra-thin heat… More >

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Randeep Singh^a,*,†, Gero Lapp^a, Jason Velardo^b, Phan Thanh Long^a, Masataka Mochizuki^c, Aliakbar Akbarzadeh^d, Abhijit Date^d, Karsten Mausolf^e, Kristin Busse^e
Frontiers in Heat and Mass Transfer, Vol.16, pp. 1-8, 2021, DOI:10.5098/hmt.16.2
Abstract In this paper, different options, based on heat pipes, for thermal management of electric vehicle (EV) battery system, at cell, module and pack level, for 40 to 400 W output heat, has been explored, analysed and compared. Cooling architecture based on embedded heat pipe (EHP) with single phase pumped cold plate (CP), as most adaptable design for low to medium range EVs, while EHP with loop heat pipe (LHP) as high performance design for high-end carlines, has been classified as potential cooling systems. Experimentally, it was shown that EHPs will provide best performance for heat acquisition at cell/module level, while… More >

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ARTICLE

V. S. Sampath Kumar^a , N. P. Pai^a,† , B. Devaki^a
Frontiers in Heat and Mass Transfer, Vol.16, pp. 1-7, 2021, DOI:10.5098/hmt.16.3
Abstract A study is carried out for the two dimensional laminar flow of conducting fluid in presence of magnetic field. The governing non-linear equations of motion are transformed in to dimensionaless form. A solution is obtained by homotopy perturbation method and it is valid for moderately large Reynolds numbers for injection at the wall. Also an efficient algorithm based finite difference scheme is developed to solve the reduced coupled ordinary differential equations with necessary boundary conditions. The effects of Reynolds number, the magnetic parameter and the pradantle number on flow velocity and tempratare distribution is analysed by both the methods and… More >

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REVIEW

Sushil Kumar^a , Robin Thakur^a, Amar Raj Singh Suri^a, Kamal Kashyap^a, Arvind Singhy^a, Sunil Kumar^a, Anil Kumar^b
Frontiers in Heat and Mass Transfer, Vol.16, pp. 1-11, 2021, DOI:10.5098/hmt.16.4
Abstract Solar thermal collector is a simple, economic, and environment friendly equipment which is used to utilize solar energy for various agriculture and industrial applications. The investigators mainly focus on the improvement of the thermal performance by providing various fins shapes underside of the absorber plate in the single pass and double pass solar thermal collector. This work discusses the influence of different shaped fins used by various researchers in improving the thermal performance of thermal collectors. Fin’s design, geometries used, and their influence on turbulence and thermal performance have also been discussed. As per the literature review and comparative study… More >

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G. R. Ganesh, W. Sridhar^*
Frontiers in Heat and Mass Transfer, Vol.16, pp. 1-11, 2021, DOI:10.5098/hmt.16.5
Abstract In this paper, heat and mass transfer of MHD Casson fluid under radiation over an exponentially permeable stretching sheet with chemical reaction and Hall Effect investigated numerically. Suitable similarity transformations are used to convert the governing partial differential equations to nonlinear ordinary differential equations. Using a numerical technique named Keller box method the equations are then solved. Study of various effects such as chemical reaction, hall effect, suction /injection on magneto hydrodynamic Casson fluid along with radiation the heat source parameter, chemical reaction parameter, Schmidt number are tabulated for various parameters. Also local parameters are calculated and compared with previous… More >

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Hongjun Wang^*, Shihong Zhang
Frontiers in Heat and Mass Transfer, Vol.16, pp. 1-5, 2021, DOI:10.5098/hmt.16.6
Abstract Catalytic combustion can inhibit the formation of CO and NOx, and greatly reduce the concentration of unburned alkanes. The hardness of tap water in Beijing is too high. In order to test whether the modified fly ash can reduce its hardness, clay, shale and fly ash bricks were prepared by catalytic combustion furnace. The results show that the fly ash brick has a great influence on Ca²⁺ and Mg²⁺ in water, increasing Ca²⁺ concentration by 59.96% and decreasing Mg²⁺ concentration by 41.22%. Thus modified fly ash could not reduce hardness of water but could be used as an Mg²⁺ adsorbent. More >

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ARTICLE

Revathi Gadamsetty^a,*,† , Venkata Subrahmanyam Sajja^b, P. Sudam Sekhar^c, Dhaneshwar Prasad^d
Frontiers in Heat and Mass Transfer, Vol.16, pp. 1-6, 2021, DOI:10.5098/hmt.16.7
Abstract An attempt has been made to investigate hydrodynamic lubrication characteristics of asymmetric roller bearings lubricated by thin fluid film under the operating behavior of line contact for a heavily loaded rigid system for normal squeezing motion with cavitation points. The lubricant follows non-Newtonian incompressible Bingham plastic fluid model where the fluid viscosity is supposed to vary with hydrodynamic pressure . The equations which govern the fluid flow such as continuity and momentum equation are solved first analytically and later numerically using MATLAB. The numerical results are achieved for the velocity, pressure, load, and traction forces by varying different physical parameters… More >

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ARTICLE

Yasushi Koito^*
Frontiers in Heat and Mass Transfer, Vol.16, pp. 1-6, 2021, DOI:10.5098/hmt.16.8
Abstract Numerical analyses were conducted for an ultra-thin heat pipe in which a thin wick layer was placed on the bottom. The vapor temperature drop caused by vapor flow friction was discussed for two types of the ultra-thin heat pipes with small and large widths. The numerical results were compared with those obtained for an ultra-thin heat pipe with a centered-wick structure. It was confirmed that the vapor temperature drop was reduced effectively by increasing the width of the heat pipe. Therefore, a wider ultra-thin heat pipe, that is, an ultra-thin vapor chamber is a promising option for nextgeneration thermal management. More >

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ARTICLE

Hussien Aziz Sahe^b,*, Ala'a Abbas Mahdi, Qusay Rasheed Al-amir
Frontiers in Heat and Mass Transfer, Vol.16, pp. 1-15, 2021, DOI:10.5098/hmt.16.9
Abstract In this study, indoor air quality and thermal comfort were investigated for two persons sitting inside an office room of dimensions (3×2.5×2.5m). The office room is equipped with personal ventilation systems positioned 50 cm from the person's face. These systems are characterized by the ability to change the rates of airflow (ATD). Experimental studies and results were conducted on a thermal manikin that simulates the human body in a sitting position, and the results are compared with CFD analysis using the k-epsilon and the RNG turbulent models. The experimental study focused on measuring the speed and temperature of the air… More >

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ARTICLE

K.V. Chandra Sekhar^*
Frontiers in Heat and Mass Transfer, Vol.16, pp. 1-6, 2021, DOI:10.5098/hmt.16.10
Abstract The behavior of unsteady MHD flow of Jeffrey fluid over an inclined porous plate was analyzed in the present article. The governing partial differential equations of the flow phenomena were solved by using powerful mathematical tool Laplace transforms. The variations of velocity, temperature of the flow with respect to dissimilar physical parameters are analyzed through graphs. The parameters of engineering interest are skin friction and Nusselt number. For better understanding of the problem, variations of skin friction and Nusselt number with respect to critical parameters are tabulated. More >

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ARTICLE

Rongge Xiao^a,*, Dong Wang^a, Shuaishuai Jin^a, Hongping Yu^b, Bo Liu^a
Frontiers in Heat and Mass Transfer, Vol.16, pp. 1-9, 2021, DOI:10.5098/hmt.16.11
Abstract Based on the Viscous Kelvin-Helmholtz theory used by D. Barnea & Y. Taitel (1993), a two-fluid stratified flow model of gas-liquid two-phase flow is established. Using the mathematical derivation, the influence of various influence factors on the stability of liquid level structure is synthesized. Compared with the criteria of D Barnea & Y. Taitel (1993) and Taitel & Dukler(1976) , and the algorithm of flow pattern transition criterion of stratified flow is proposed. According to the data of multiphase flow experimental loop, the influence of liquid viscosity and the instantaneous volume flow rate change of gas-liquid two-phase on the transition… More >

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ARTICLE

Silpisikha Goswami^a,b, Dipak Sarma^b
Frontiers in Heat and Mass Transfer, Vol.16, 2021, DOI:10.5098/hmt.16.12
Abstract This study includes the observation of electrically conducting non-Newtonian fluid flow through a vertical porous plate considering the effect of the induced magnetic field. Our approach is numerical to investigate how the variation of magnetic Prandtl number and Eckert number effect the flow profiles. Influence of Casson parameter and Hartmann number in the profiles is also observed and depicted in graphs. The rate of heat transfer, the rate of mass transfer and the skin friction are calculated and presented in tables. A significant effect of magnetic Prandtl number and Eckert number is observed. We compared our results with some previous… More >

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ARTICLE

Wei Tian^a , Mingjun Pang^a,*, Na Xu^b,†
Frontiers in Heat and Mass Transfer, Vol.16, pp. 1-12, 2021, DOI:10.5098/hmt.16.13
Abstract Drag reduction (DR) by the additive of mixed surfactant and polymer is investigated in detail in a rotating disk apparatus (RDA). Polyethylene oxide (PEO) and Cetyltrimethyl ammonium chloride (CTAC)/sodium salicylate (NaSal) are chosen as polymer and surfactant, respectively. It is investigated on the influence of combination concentration of polymer & surfactant, temperature and Reynolds number on the drag-reducing rate. The present experimental results show that the drag-reducing rate of the mixed solution is definitely higher than that of the pure PEO or CTAC/NaSal solutions. This phenomenon is especially sharp at the high temperature and/or the large Reynolds number. When the… More >

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ARTICLE

Kapil Dev Choudhary, Shyam Sunder Yadav^† , Mani Sankar Dasgupta
Frontiers in Heat and Mass Transfer, Vol.16, pp. 1-10, 2021, DOI:10.5098/hmt.16.14
Abstract In the current work, we simulate the condensation of supercritical CO₂ during its high speed flow inside two different converging-diverging nozzles. We use the homogeneous equilibrium method and the classical nucleation theory based non-equilibrium phase change model for this purpose. The simulation results indicate significant influence of the nozzle inlet condition, nozzle shape and the fluid thermophysical behaviour on the nonequilibrium conditions prevailing inside the nozzles. We observe very low, ∼0.15 K, supercooling for the flow of CO₂ inside the Claudio Lettieri nozzle compared to the supercooling of ∼3 K observed for the Berana nozzle. Very high nucleation rate (∼… More >

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ARTICLE

B. Gangadhara Rao^a,*, K. Elangovan^b, K. Hema Chandra Reddy^a, M. Arulprakasajothi^c
Frontiers in Heat and Mass Transfer, Vol.16, pp. 1-8, 2021, DOI:10.5098/hmt.16.15
Abstract In this research, the 3-D coupled thermal electric model analyses on a sandwich bus bar are presented for the comparison of F Class & B Class of insulation. IEC defines the maximum temperature limit at the conductor based on the class of insulation. This paper gives the clarity on the variation on the current density i.e, the size of the conductor by varying the class of insulation. The study is conducted on tin plated 2000 A sandwich busbar system. The sandwich bus bar is made of copper conductors with tin plating and enclosed by an aluminum cover along its length.… More >

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ARTICLE

Changming Ling^a,b,*,†, Xiaobo Lou^c, Yin Zhong^b
Frontiers in Heat and Mass Transfer, Vol.16, pp. 1-6, 2021, DOI:10.5098/hmt.16.16
Abstract To solve the issues of high-energetic consumption, high-cost and high-carbon emissions in the processes of reverse osmosis seawater desalination technology, this study proposed and implemented a tidal energy-gathering supercharger with the concept of using green tidal energy to directly produce high-pressure-seawater-driven reverse osmosis seawater desalination system. Compared with the traditional way of using tidal energy to produce electric power in order to produce high-pressure water for the system, this technology could save energy that may lost in two transferring process thus can improve the energy efficiency of the whole system, lower its running cost, and realize the green production concept… More >

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ARTICLE

Amnart Boonloi^a, Withada Jedsadaratanachai^b,*
Frontiers in Heat and Mass Transfer, Vol.16, pp. 1-16, 2021, DOI:10.5098/hmt.16.17
Abstract This research reports numerical examinations on fluid flow, heat transfer behavior and thermal performance analysis in a circular tube equipped with modified V-baffles (CTMVB). The modified V-baffle (MVB) is a combination vortex generator between V-baffles/V-orifices which are placed on the tube wall and V-baffles which are inserted at the core of the tested tube. The MVB height is separated into two parts; b1 represents the MVB height on the tube wall, while b2 represents the MVB height at the core of the tested round tube. The MVB height to tube diameter ratios, b/D, are adjusted; b₁/D = 0.05, 0.1, 0.15… More >

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ARTICLE

Yan Chen^a , Qingxin Ba^b,*, Xuefang Li^b
Frontiers in Heat and Mass Transfer, Vol.16, pp. 1-9, 2021, DOI:10.5098/hmt.16.18
Abstract The heat transfer of supercritical CO₂/DME mixtures was modeled in this study for a mass ratio of 95/5 for cooling in horizontal helically coiled tubes. The CO₂/DME heat transfer coefficient was higher in the high-temperature zone than with pure CO₂. The heat transfer of CO₂/DME (95/5) was predicted for various mass fluxes, heat fluxes and pressures. The CO₂/DME heat transfer coefficient increased with the mass flux due to the increased turbulent diffusion, and first increased but then decreased with the heat flux. The peak heat transfer coefficient of CO₂/DME shifted toward the high-temperature region as the operating pressure increased. The… More >

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ARTICLE

Ming Zhao^*, Yuhao Zheng
Frontiers in Heat and Mass Transfer, Vol.16, pp. 1-9, 2021, DOI:10.5098/hmt.16.19
Abstract The performance optimization of the triangular-tube phase change heat accumulator is carried out from three aspects. The first is to compare with three different types tubes: the traditional round tube, the square tube, and the elliptical tube. Results show that equilateral triangle tube has the best heat storage and release characteristics. The second is to study the sub-cavity heat accumulator model based on multiphase change materials on the basis of the triangular tube. The third is to study the turn-over triangular tube heat accumulator. Both the flip function through discrete point fitting and the best reversal time are obtained. More >

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ARTICLE

Kafel Azeez Mohammed^a,*, Ahmed Mustaffa Saleem^b , Zain alabdeen H. Obaid^a
Frontiers in Heat and Mass Transfer, Vol.16, pp. 1-8, 2021, DOI:10.5098/hmt.16.20
Abstract Numerical investigation is performed for the determination of Nusselt number of ZnO, TiO₂ and SiO₂ nanoparticles dispersed in 60% ethylene glycol and 40% water inside inclined cylinder for adiabatic and isothermal process. The present study was conducted for both the constant heat flux (10,000 W/m²) and constant wall temperature (313.15 K) boundary conditions. At the inlet, the uniform axial velocity and initial temperature (293 K) were assumed. The results show the change of average Nusselt number at Reynolds number (400), Rayleigh number (10⁶) and volume fraction percentage (2%). From results for adiabatic process when increasing the slop up to (45o),… More >

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ARTICLE

Jian Li^1,2, Yongbin Zhang^1,*
Frontiers in Heat and Mass Transfer, Vol.16, pp. 1-5, 2021, DOI:10.5098/hmt.16.21
Abstract The paper introduces the flow equations for the fluid flows in a cylindrical tube respectively on the macroscale, multiscale and nanoscale, especially recently developed ones. It manifests that when these equations should be used in calculating the transferred mass and what should be taken into consideration when the tube inner radius is reduced to very small values. It gives an important indication on how to treat the mass transfer calculation for the tube flow on different size scales. More >

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Kaprawi Sahim^*, Dewi Puspitasari, Nukman
Frontiers in Heat and Mass Transfer, Vol.16, pp. 1-6, 2021, DOI:10.5098/hmt.16.22
Abstract The recent trend application of the nanofluids is used in some industrial equipment such as tube heat exchanger, double pipe exchanger and shell-tube type heat exchanger. The Triangle tubes may be used in the heat exchanger. Thus, this experimental study reports the convective heat transfer performance of the aluminum oxide-water nanofluids flowing in the triangle channel. In this study, the amount of the volume fraction of the Al₂O₃ used was 0.1 %, 0.2 %, and 0.3 respectively in base-water as the nanofluids and the Reynolds numbers were varied from about 1000 to 7000. The channel was heated by the electric… More >

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ARTICLE

Roshan Devidas Bhagat^a,*, Samir J. Deshmukh^b
Frontiers in Heat and Mass Transfer, Vol.16, pp. 1-16, 2021, DOI:10.5098/hmt.16.23
Abstract Numerical analysis of passive two phase fluid flow in a 3D Closed Loop Pulsating Heat Pipe (CLPHP) with turns in evaporator and condenser section is carried out. Water is used as working fluid. The volume of fluid model (VOF) is used to simulate passive two-phase fluid flow in a Closed Loop Pulsating Heat Pipe. Filling ratio (FR) of is kept in the range of 60 to 70%. The evaporator temperature is set in the range of 353 K. The condenser temperature is set in the range of 298 K. The contours of volume fraction water, wall temperature and contours of… More >

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D. Santhi Kumari^a,*, Venkata Subrahmanyam Sajja^a, P. M. Kishore^b,†
Frontiers in Heat and Mass Transfer, Vol.16, pp. 1-10, 2021, DOI:10.5098/hmt.16.24
Abstract This study attempts to explore a qualitative analysis of the effects of Soret on an unsteady magnetohydrodynamics free convection flow of a chemically reacting incompressible fluid past an infinite vertical plate embedded in a porous medium taking the source of heat and thermal radiation into account as well as viscous dissipation. The central equations are scrupulously converted into sets of coupled nonlinear partial differential equations for providing logical solutions. The method of Galerkin finite element is used considering appropriate boundary conditions for diverse physical metrics and then numerically analyzed employing MATLAB. A significant change in velocity, temperature, concentration profiles is… More >

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ARTICLE

Rongge Xiao^a,*, Shuaishuai Jin^a, Xin Feng^b, Peng Zhang^c, Zheng Dai^c
Frontiers in Heat and Mass Transfer, Vol.16, pp. 1-7, 2021, DOI:10.5098/hmt.16.25
Abstract With the increasing production and use of natural gas, the supersonic nozzle has become focus of the impurity removal research. In this paper, the modified classical nucleation model is used as the condensation nucleation model, and the Gyarmathy growth model is selected as the droplet growth model. Based on the assumption of no phase slip and Eulerian two fluid model, the flow control equation of wet natural gas is established. By giving the selection criteria as a turbulence equation, the SRK real gas equation is used to carry out the corresponding numerical simulation. The required supersonic nozzle structure and grid… More >

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