This work experimentally studied the convective flow and heat transfer characteristics of a novel nanostructured heat transfer fluid: "ethanol/polyalphaolefin nanoemulsion" flowing through 12 circular minichannels of 1-mm diameter each. Ethanol/polyalphaolefin nanoemulsion is a thermodynamically stable system formed by dispersing ethanol into a mixture of "polyalphaolefin (PAO)" and surfactants...

turbulence structure on the gas side of a wavy stratified flow was experimentally investigated in a near horizontal 18.7 cm (h) 10 cm (w) 5.5m (l) rectangular duct.by applying the variable interval time averaging (vita) technique to the hot wire anemometer measurements frequency of occurrence of turbulent events were detected near the air-water interface. experimental results showed that freque...

We developed a parallel Bayesian optimization algorithm for large eddy simulations. These simulations challenge optimization methods because they take hours or days to compute, and their objective function contains noise as turbulent statistics that are averaged over a finite time. Surrogate based optimization methods, including Bayesian optimization, have shown promise for noisy and expensive ...

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Several researches dealing with the single-phase forced convection heat transfer inside microchannels have been published in the past decades. The performance of liquid flow has been proved that agrees with the conventional correlations very well. However, owing to the low heat transfer coefficient of gaseous flow, it is more difficult to eliminate the effects of thermal shunt and heat loss tha...

Convection over the building envelope is a critical determinant of building cooling load, but parameterization of convection in building energy models and urban computational fluid dynamics models is challenging. An experimental investigation intended to clarify the heat transfer mechanism of a convective wall boundary layer (WBL) on a leeward, vertical building wall was conducted at the Compre...

Laminar and turbulent natural convection inside concentric spherical shells with isothermal cold and hot boundaries is numerically investigated up to Rayleigh number values Ra 6 10 and Pr = 0.71. The study utilizes direct numerical simulation (DNS), large eddy simulation (LES) and Reynolds averaged Navier– Stokes (RANS) approaches for investigation of the laminar, transitional and fully develop...

Heat transfer enhancement technology has the aim of developing more efficient systems as demanded in many applications. An available passive method is represented by the employ of rough surfaces. Transversal turbulators enhance the heat transfer rate by reducing the thermal resistance near surfaces, because of the improved local turbulence; on the other hand, higher losses are expected. In this...

Wen-Jei Yang Department of Mechanical Engineering and Applied Mechanics, The University of Michigan, Ann Arbor, Michigan 1 A n experimental study is performed to investigate the pressure drop distribution and turbulence intensity for airflow through a stack of parallel plates with periodic interruptions. The interrupted surfaces are constructed in an offset-strip f6rm and a perforated form. Hot...

The time-dependent vertical structure of cold accretion disks and their thermal stability have been studied with turbulent heat transfer being included. A strong turbulent heat transport enforces a nearly adiabatic stratification and the disk evolves quasi-homologously, although homology is broken by the outer boundary condition. The radiative energy loss scales with the disk’s optical depth τ ...