A comparative study on performances of rod-baffle (RB) and segment-baffle (SB) heat exchangers was carried out by numerical simulations under the same conditions. The results show that the overall heat transfer efficiencies are similar in these two types of heat exchangers with the same heat transfer areas. But RB heat exchangers show more uniform and smooth fluid flow, as well as much lower pressure in the shell side compared to SB counterparts. These detailed characteristics of heat transfer and fluid flow evidence better performances in RB heat exchangers and also provide a deeper insight into design and optimization of shell-and-tube heat exchangers.
Solar flat-plate collector is an important component in solar-thermal system, and its optimization is critical for the efficiency of energy utilization. In this paper, a comparative study on the thermal performance of solar flat-plate collector was carried out by numerical simulation under the conditions of different thicknesses and materials of absorber plate. The results show that the increase of absorber plate thickness contributes to restraining convection loss. The collector efficiency levels off when the absorber plate thickness reaches a certain value. In considering thermal performance and production cost, aluminum is an optimal material for absorber plate.
Within a micromechanical framework, the effect of surface energy is taken into account to explore the size-dependent yield criterion of nanoporous materials under complex stress states. A theoretical picture of the yield behavior on an octahedral plane is illustrated as functions of the surface properties and void size. The prominent size dependence of the yield criterion of nanoporous materials highlights the importance of the surface effect in analyzing the strength of nanostructured materials. The results demonstrate a fundamental framework to extend continuum strength theories to the nanoscale with substantial surface effect, which may be useful for evaluating the mechanical integrity of nanostructured materials.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.