Shuilian Li¹, Fan Zeng¹, Xinli Wei^2,*

FDMP-Fluid Dynamics & Materials Processing, Vol.20, No.5, pp. 939-955, 2024, DOI:10.32604/fdmp.2023.043614 - 07 June 2024

Abstract In order to increase the efficiency of solar air collectors, a new variant with a protrusion is proposed in this study, and its performances are analyzed from two points of view, namely, in terms of optics and thermodynamics aspects. By comparing and analyzing the light paths of the protrusion and the dimple, it can be concluded that when sunlight shines on the dimple, it is reflected and absorbed multiple times, whereas for the sunlight shining on the protrusion, there is no secondary reflection or absorption of light. When the lighting area and the properties of… More >

Abeer H. Falih^*, Basima Salman Khalaf, Basim Freegah

Frontiers in Heat and Mass Transfer, Vol.22, No.2, pp. 597-613, 2024, DOI:10.32604/fhmt.2024.049812 - 20 May 2024

Abstract In this study, the primary objective was to enhance the hydrothermal performance of a dimpled tube by addressing areas with low heat transfer compared to other regions. To accomplish this, a comprehensive numerical investigation was conducted using ANSYS Fluent 2022 R1 software, focusing on different diameters of dimples along the pipe’s length and the distribution of dimples in both in-line and staggered arrangements. The simulations utilized the finite element method to address turbulent flow within the tube by solving partial differential equations, encompassing Re numbers spanning from 3000 to 8000. The study specifically examined single-phase… More > Graphic Abstract

Tao Wang¹, Zhen Tian¹, Chen Gao¹, Quanfu Gao¹, Kewei Song^1,*

The International Conference on Computational & Experimental Engineering and Sciences, Vol.27, No.4, pp. 1-3, 2023, DOI:10.32604/icces.2023.8880

Abstract With the rapid development of the economy and the increasing consumption of fossil energy, energysaving becomes imperative [1,2]. Improving the heat transfer efficiency of heat exchangers, which are widely applied in many fields, is important for energy utilization [3,4]. Twisted tube can produce secondary flow, increase turbulence and thin thermal boundary layer, and hence the enhancement of heat transfer [5-9]. However, the mixture of the fluid between the center of the twisted tube and the region around the tube is still not effectively improved. Thus, the heat transfer of the twisted tube can be further… More >

O. M. Oyewola^a,b,* , M. O. Petinrin^a , and H. O. Sanusi^a

Frontiers in Heat and Mass Transfer, Vol.20, pp. 1-8, 2023, DOI:10.5098/hmt.20.16

Abstract The flow and heat transfer behaviour of channels with dimples and protrusions of spherical and piriform shapes was numerically explored by solving the Navier-Stokes and energy equations with a CFD software, the ANSYS Fluent 19.3, in the range of Reynolds numbers from 8,500 to 59,000. The values of the Nusselt number and friction factors were estimated and the non-dimensional Performance Evaluation Criterion (PEC) was determined to measure the thermal-hydraulic performance. The results reveal that the piriform protruded channel demonstrated a higher thermal performance with Nusselt number values of 36%, 15%, 23%, and 9% than the… More >

Mousa Aqeel Ali^*, Saad Najeeb Sheha^b

Frontiers in Heat and Mass Transfer, Vol.19, pp. 1-10, 2022, DOI:10.5098/hmt.19.39

Abstract In this study, the hydrothermal water flow characteristics using a dimpled inner tube heat exchanger are investigated experimentally and numerically. A numerical analysis has performed on two types of dimpled tubes (In-lined and staggered distributions) for two distribution angles 60o and 90o , and two dimple diameters(4 mm and 6 mm) with constant pitch ratio (X/d=8). In experimental part, a staggered arrangement dimpled inner tube distribution with angle 60o , dimple diameter of 6 mm and constant pitch ratio (X/d=8)is used as well as plain tube. The results illustrate that the heat transfer as Nusselt More >

Masanori Kikuchi ¹

CMES-Computer Modeling in Engineering & Sciences, Vol.11, No.2, pp. 49-60, 2006, DOI:10.3970/cmes.2006.011.049

Abstract Three kinds of fracture specimens are tested under different constraint conditions. By the SEM(Scanning Electron Microscope) observation, it is shown that the roughness of fracture surface is different from each other largely. This is the effect of constraint condition. The dimple fracture process is simulated by the finite element method using Gurson’s constitutive equation, and the crack tip stress fields are obtained. The distributions of stress triaxiality qualitatively agree with the experimental results. The J-R curves obtained also qualitatively agree with those of experiments, and the fracture surface roughness is well simulated. More >