Abstract The T-shaped groove surface with groove width of 0.3 to 1.2 mm and groove depth of 0.6 to 1.5 mm is prepared on the copper surface by using electric spark wire cutting technology, Set up a set of wall temperature measurement, bubble visualization and steady flow heating test bench. Experimental observations of boiling heat transfer of deionized water on different heat transfer surfaces are achieved. The boiling curves of T-shaped surface such as superheat, heat flux and heat transfer coefficient were plotted. The effect of heat transfer area on the heat transfer performance was investigated, and the bubble growth process was studied by using finite element simulation software. The effect of size on heat transfer performance is explained by experiment and simulation. It is found that the influence of groove width on heat transfer performance is greater than that of groove depth, under the reasonable width of the groove, the larger the depth of the groove, the easier it is to reach the required temperature for the vaporized core generation. The optimal size value of T-shaped grooves in this size range is selected, and the surface of T-grooves at different scales is constructed by laser marking technology. The boiling heat transfer performance of four kings of surfaces including smooth surface and laser scanning surface was studied. Studies have shown, heat transfer effect of multi-scale T surface is always the best,1.31 times of single scale surface,2.38 times of smooth surface and 2.83 times of laser scanning surface. The surface with micro structure can effectively promote boiling heat transfer by wire cutting and laser machining.
Abstract This paper presents a molecular dynamics study on the effects of different boundary wall temperatures in the range of 84 K to 133 K on the flow characteristics of Argon fluid flow. An external force of 0.002 eV/A is enforced on the fluid at the entry of microchannels with roughened and smooth surfaces. Roughness elements are in cubic shape, and fluid atoms are structured inside microchannel in two lateral regions near microchannel walls, while; middle region of the microchannel contains...
In this paper, the effect of changing tube slope on the critical heat flux for the evaporation of upward saturated flow of a liquid (water) in a near-vertical tube has been studied numerically. For this purpose, the effect of increasing the pipe slope and changing the wall temperature and the inlet fluid temperature on the volume fraction of vapor, heat transfer coefficient, heat flux and velocity profile is analyzed. In the most industrial units, boiling in diagonal channels is very important. ...
Abstract In this research, laminar flow and heat transfer of two-phase water/Ag nanofluid with 0–6% volume fraction of nanoparticles at Re = 150–700 in a curved geometry are simulated using finite volume method. Studied geometry is an elliptical curved minichannel with curvature angle of 180o. Forced and natural flow of two-phase nanofluid is simulated at Gr = 15,000, 35,000 and 75,000. For estimation of nanofluid flow behavior, two-phase mixture method is used. The second-order discretization a...
In this paper, the hydrodynamics and heat transfer parameters of nanofluids are investigated using CFD analysis. Laminar convective heat transfer of alumina–water nanofluids with 0, 1%, and 2% volume fraction in a straight microtube heat sink under constant wall heat flux condition is studied. This work is performed in two parts. In the first part, the single-phase and two-phase approaches have been used for modeling heat transfer of pure water and alumina–water nanofluids in a straight microtub...
Last. Reza Fazaeli(IAU: Islamic Azad University)H-Index: 13
view all 4 authors...
Abstract Present paper employs Molecular Dynamic Simulation (MDS) Method to study the effects of suspending 2, 4 and 6 Copper nanoparticles into Argon base fluid, flowing inside microchannel with square cross section under boiling flow condition. Fluid flow is supported by an external driving force of 0.002 eV/A at the inlet section of microchannel and boiling process is supported by boundary wall temperature of 108 K. Afterward, statistical approach is employed as new insight for data analysis ...
Last. Daniel Maynes(BYU: Brigham Young University)H-Index: 24
view all 4 authors...
Abstract Periodically patterned superhydrophobic surfaces with rectangular rib and circular post arrays were utilized as heat transfer surfaces in a boiling apparatus with the water pool undergoing saturated pool boiling. The surface microstructures were geometrically defined by cavity fraction (the ratio of projected cavity area to surface area), pitch (the center to center distance between microfeatures), and feature height. Surface heat flux and surface superheat, the difference between the h...
Abstract In two-phase heat transfer, promising issues include not only improving the boiling performance but also the surface temperature uniformity and stability, which indicate that how long the system maintains thermal stability without a failure on the surface. In this study, the merits of micro-nano hybrid surfaces (MNHS) are discussed for enhancing the thermal uniformity/stability and boiling heat transfer performance. Spatial/temporal heat transfer characteristics are evaluated on MNHS us...
Last. V. V. Salomatov(RAS: Russian Academy of Sciences)H-Index: 8
view all 4 authors...
Abstract The results of the numerical simulation of heat transfer from the combustion products of coal and coal-water fuels (CWF) to the internal environment. The mathematical simulation has been carried out on the sample of the pipe surfaces of the combustion chamber of the boiler unit. The change in the characteristics of heat transfer (change of thermochemical characteristics) in the conditions of formation of the ash deposits have been taken into account. According to the results of the nume...
Abstract Heat transfer enhancements are used extensively to improve the performance of heat exchangers and to reduce their running cost. Longitudinal vortices can enhance heat transfer greatly. To enrich the mechanism of heat transfer enhancement produced by longitudinal vortices, this paper addresses the mechanisms of heat transfer enhancement enforced by longitudinal vortices generated by vortex generators (VGs) from another view point. The view point is based on the convective transport equat...