An analytical model is developed for the startup transient of asymmetrical flat-plate and diskshaped heat pipes. The model solves the proper transient heat conduction equations for the heat pipe wall and liquid-wick regions. A quasi-steady state, pseudo three-dimensional approximation is used for the vapor transi’ent behavior. The heat transfer within the wall and liquid-wick regions is coupled...

Heat pipes offer passive transport of heat over long distances without incurring a significant drop in temperature. Topological and microstructural details of the wick material embedded in a heat pipe help determine its thermal performance. A good understanding of pore-scale transport phenomena is crucial to enhancing heat pipe performance. In this study, pore-scale analysis of thin-film evapor...

welding produces residual stresses and distortion, having detrimental effect on structure integrity and service performance of the welded pipe joints. this paper investigates residual stresses and distortion during gas metal arc welding (gmaw) of pipes of schedule 40 and 60, nominal diameter 100mm and 200mm and thickness 8mm and 10mm with ansi flanges of class 300#. welding parameters including...

One way to increase the heat transfer is to use perforated twisted tapes with different hole diameters, which largely improve heat transfer with an increase in the heat transfer area at the constant volume and more mixed flow. In the previous studies, the effect of nanofluids with perforated twisted tapes is less studied. In this work, the performance of water / iron oxide nanofluid in a double...

A manufacturing process plan was developed for a welded condenser utilizing a sintered wick. Electronic devices have progressed to the point where new designs are limited by the thermal management system used to ensure safe operating temperatures. Coupling the effects of high surface area of multiple condensers, the low thermal resistance of loop heat pipes, and the increased dissipation rates ...

As air cooling of electronics reaches the limits of its applicability, the next generation of cooling technology is likely to involve heat pipes and singleor two-phase coolant loops (including perhaps loop thermosyphons, spray cooling, vapor compression refrigeration cycles, and loop heat pipes). These technologies are not suitable for analysis using 2D/3D computational fluid dynamics (CFD) sof...

A detailed description of a concentric annular heat pipe (CAHP) operation is presented in low to moderate temperature ranges (50–200◦C). The steady-state response of a CAHP to various heat fluxes in the evaporator and condenser sections are discussed. Two-dimensional mathematical modeling of the fluid flow and heat transfer in the annular vapor space and the wicks are described. The fundamental...

Heat EXchangers (HEX) that are used in City Gate Station (CGS) systems are modeled numerically to recover the exhaust waste heat. It was tried to find the best viscous model to obtain results in accordance with experimental results and to change the heat exchanger design. This HEX is used for recovering heat from exhaust flue gas with a mixture of 40% water and 60% ethylene glycol as the coolin...

A nanofluid is mixture of nano sized particles and a base fluid. This paper investigates by using laboratory based double pipe heat exchanger model, the performance of nanofluid containing about 48.46nm  particle size nanoparticles (ZnO) without or with addition of nonionic surfactant Rokanol K7 (500ppm) into the base fluid double distilled water to prepared three different concentrations 1.0%,...