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… More >

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 More >

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… More >

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… More >

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… More >

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 More >

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 More >

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 >

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… More >

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 More >