An experimental investigation was conducted to examine the effects of variations in temperature and volume fraction on steady-state effective thermal conductivity two different nanoparticle suspensions. Copper aluminum oxide, CuO Al2O3, nanoparticles with area weighted diameters 29 36nm, respectively, were blended distilled water at 2%, 4%, 6%, 10% fractions resulting suspensions evaluated temperatures ranging from 27.5to34.7°C. The results indicate that material, diameter, fraction, bulk...

A steady-state method was used to evaluate the effective thermal conductivity of Al2O3∕distilled water nanofluids with nanoparticle diameters 36 and 47nm. Tests were conducted over a temperature range 27–37°C for volume fractions ranging from 0.5% 6.0%. The enhancement two demonstrated nonlinear relationship respect temperature, fraction, size, increases in particle size all resulting an increase measured enhancement. most significant finding effect that variations had on nanofluids. largest...

The natural convection heat transfer characteristics of [Formula: see text] nanofluids comprised 47 nm, and water, with volume fractions ranging from 0.5% through 6%, has been investigated a set experimental measurements. temperature the heated surface Nusselt number different tests clearly demonstrated deviation that pure base fluids (distilled water). In investigation, deterioration coefficient was observed increases fraction nanoparticles in nanofluids. phenomenon further visualization...

Abstract An experimental investigation of the combustion behavior nano-aluminum (n-Al) and oxide (n-Al 2 O 3 ) particles stably suspended in biofuel (ethanol) as a secondary energy carrier was conducted. The heat (HoC) studied using modified static bomb calorimeter system. Combustion element composition surface morphology were evaluated SEM/EDS N-Al n-Al 50- 36-nm diameters, respectively, utilized this investigation. experiments performed with volume fractions 1, 3, 5, 7, 10% for n-Al, 0.5,...

An experimental study has been conducted to examine the effects of macroscale, microscale, and nanoscale surface modifications in water pool boiling heat transfer determine different enhancing mechanisms at scales. Nanostructured surfaces are created by acid etching, while microscale macroscale structured synthesized through a sintering process. Six structures studied as individual collectively integrated from macroscale: polished plain, flat nanostructured, porous, modulated nanostructured...

Nanofluids are being studied for their potential to enhance heat transfer, which could have a significant impact on energy generation and storage systems. However, only limited experimental data metal metal-oxide based nanofluids, showing enhancement of the thermal conductivity, currently available. Moreover, majority available been obtained using transient methods. Some controversy exists as validity measured possibility that this may be an artifact methodology. In current investigation,...

An experimental investigation of the initial heating rate 50 nm ferromagnetic nanoparticles (Fe3O4) suspended in water and incorporated an agar gel was conducted to study thermal effects resulting from Brownian motion hysteresis losses. Particles were placed alternating current magnetic field with intensities 28.6, 35.8, 38.9, 43.0 kA m−1, at frequencies ranging 161 284 kHz. The specific absorption based on calculated contributions losses are compared analyzed.

Abstract Spherical Cu nanocavity surfaces are synthesized to examine the individual role of contact angles in connecting lateral Rayleigh-Taylor wavelength vertical Kevin-Helmholtz on hydrodynamic instability for onset pool boiling Critical Heat Flux (CHF). Solid and porous pillar sintered investigate structure pitch at millimeter scale, named as module wavelength, CHF. Last, spherical nanocavities coated pillars create a multiscale structure, which is studied collective relative...

Spherical glass and copper beads have been used to create bead packed porous structures for an investigation of two-phase heat transfer bubble dynamics under geometric constraints. The results demonstrated a variety characteristics range heating conditions. generation, growth, detachment during the nucleate pool boiling filmed, surface temperatures flux were recorded, theoretical models employed study dynamic characteristics. Computer simulation combined with experimental observations...

Static nanodroplets and dynamic contact line (CL) movements were visualized by an in situ transmission electron microscope (TEM) liquid cell technique at nanometer spatial resolution. Crawling sliding of nanoscale CL observed. The crawling happened a capillary number (Ca) range ∼10–9 to ∼10–8, the Ca ∼10–8 ∼10–7. Three dimensional (3D) image construction had been employed study static angles (CAs) nanoscale. CA hysteresis was observed but not crawling. energies associated with analyzed...

A combined experimental and analytical investigation of single proton exchange membrane (PEM) fuel cells, during cold start, has been conducted. The temperature influence on the performance a PEM cell start failure was evaluated experimentally to determine mechanisms performance. voltage, current, power characteristics were investigated as function load, hydrogen flow rate, temperature. for analyzed, various explored characterized. In an effort better understand operational behavior modes,...

The critical heat flux values of copper substrates were increased from 87 to 125 W/cm2 by using a simple chemical process resulting in growth micro and nano-scale structures on the surface. Pre- post-test surface analysis revealed that morphology features these changed during boiling accompanied change oxide layer composition. Boiling performance nano-structured samples was repeatable when testing at lower fluxes.

An experimental study of the pool boiling two-phase heat transfer on a sintered Cu microparticle porous structure module surface is conducted. Enhanced capacity this has been reported, and characteristics have investigated. The bubble dynamics nucleate size distribution compared to theoretical predictions, speculated mechanisms discussed.

More and more micro/nanofluidic devices are proposed to improve the performance in thermal medical applications, nanobubbles promise a new way of controlling heat flow at high spatial temporal resolutions. The long lifetime static has been extensively investigated both experiments theoretical modeling, but dynamic growth lacks comprehensive understanding. Therefore, we conduct an experimental investigation nanobubble graphene liquid cell, under oversaturation conditions dissolved hydrogen...

A study has been conducted to examine the effects of macroscale, microscale, and nanoscale surface modifications in water pool boiling heat transfer determine combining multiple scales. Nanostructured surfaces were created by acid etching, while microscale macroscale manufactured through a sintering process. Six structures studied as individual and/or collectively integrated surfaces: polished plain, flat nanostructured, porous, modulated nanostructured porous. Boiling performance was...

Experimental evidence exists that the addition of a small quantity nanoparticles to base fluid, can have significant impact on effective thermal conductivity resulting suspension. The causes for this are currently thought be due combination two distinct mechanisms. first is change in thermophysical properties suspension, from difference fluid and particles, second transport energy by Brownian motion particles. In order better understand these phenomena, theoretical model has been developed...

A combined experimental and analytical investigation of single proton exchange membrane (PEM) fuel cells, during cold start has been conducted. The temperature influence on the performance a PEM cell failure was evaluated experimentally to determine mechanisms performance. voltage, current power characteristics were investigated as function load, hydrogen flow rate, temperature. for analyzed, various explored characterized. In an effort better understand operational behavior modes, numerical...

An experimental study of the pool boiling two-phase heat transfer on a sintered Cu microparticle porous structure module surface is conducted. Enhanced capacity this has been reported, and characteristics have investigated. The bubble dynamics nucleate size distribution compared to theoretical predictions, speculated mechanisms discussed.

With the rapidly increasing demand for efficient, small, light, low cost, and reliable electronic devices, nano-scale thermal transport properties of semiconductors has become a prominent focus research. Molecular dynamic simulation emerged as powerful compliment to experiment is beginning play crucial role in tailored material improved management devices. The conductivity semiconductor been investigated using Stillinger-Weber (SW) Modified Embedded Atom Method (MEAM) potential model,...