Aqueous nanofluids containing paraffin-filled MWCNTs for improving effective specific heat and extinction coefficient.

This paper presents measurements of the effective specific heat and the extinction coefficient for aqueous nanofluids dispersed with paraffin-filled Multi-Walled Carbon NanoTubes (MWCNTs). The MWCNTs were filled with paraffin wax by capillary action. Centrifugal decanting was used to modify the traditional two-step method so as to produce a nanofluid dispersion that was more stable than that produced by the traditional method.

Effect of mesh wick geometry on the maximum heat transfer rate of flat-micro heat pipes with multi-heat sources and sinks.

This paper presents a theoretical investigation of the thermal characteristics of flat-micro heat pipes (FMHPs) with multi-heat sources and sinks. Analytical solutions of the pressure and the temperature distributions of FMHPs with multi-heat sources and sinks were obtained based on the modified liquid pressure drop. The solutions were used to identify the key engineering parameters of a mesh wick with microscale length that affect the maximum heat transfer rate of the FMHPs with multi-heat sources and sinks.

Thermal characteristics of silicon wafer-based TVCs (thin vapor chambers) with disk-shape using DI water.

This paper analytically and experimentally investigates the thermal characteristics of disk-shaped, silicon wafer-based thin vapor chamber (TVC) using de-ionized water as the working fluid. The maximum heat transfer rate, the maximum temperature, and the thermal resistances of the TVCs were measured experimentally. An analytical model based on the modified liquid pressure drop through a micro-pin-fin wick and the capillary limit was developed to determine the maximum heat transfer rate.

Effect of surfactants on the stability and solar thermal absorption characteristics of water-based nanofluids with multi-walled carbon nanotubes.

This paper reports the effect of various surfactants on the suspension stability and the solar thermal absorption characteristics of water-based nanofluids containing multi-walled carbon nanotubes (MWCNTs) that can be used as working fluids for volumetric solar thermal receivers. The water-based MWCNT nanofluids were prepared using a two-step method with four commonly used surfactants: sodium dodecylbenzenesulfonate (SDBS), cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS), and Triton X-100 (TX-100). The stability of the four surfactant-treated nanofluids was analyzed for over a month with an in-house developed laser transmission system.

Note: effect of the tilting angle of the wire on the onset of natural convection in the transient hot wire method.

In this paper, numerical and experimental investigations are systematically performed to identify the effect of the tilting angle of the wire on the onset of natural convection in the transient hot wire method (THWM), a widely accepted technique for measuring the thermal conductivity of various media, especially nanofluids. To validate our numerical simulation code, the numerical results are compared with theoretical solutions as well as with experimental results. Based on the results, we show that the onset time of natural convection in THWM decreases rapidly with the increase of the wire's tilting angle from vertical position.

Production of aqueous spherical gold nanoparticles using conventional ultrasonic bath.

A conventional ultrasonic bath was used to examine the feasibility of forming aqueous spherical gold nanoparticles (GNPs) under atmospheric conditions. The effects of ultrasonic energy on the size and morphology of GNPs were also investigated. Highly monodispersed spherical GNPs were successfully synthesised by sodium citrate reduction in a conventional ultrasonic bath, without an additional heater or magnetic stirrer, as evidenced by ultraviolet-visible spectra and transmission electron microscopy.

Electrokinetic effects of charged nanoparticles in microfluidic Couette flow.

The behavior of Couette flow of nanofluids composed of negatively-charged nanoparticles dispersed in aqueous NaCl solutions is studied theoretically. The equation for calculating the Couette flow velocity profiles is derived. The induced electric fields and velocity profiles are calculated as a function of key parameters including nanoparticle size and volume fraction.

Round-robin test on thermal conductivity measurement of ZnO nanofluids and comparison of experimental results with theoretical bounds.

Ethylene glycol (EG)-based zinc oxide (ZnO) nanofluids containing no surfactant have been manufactured by one-step pulsed wire evaporation (PWE) method. Round-robin tests on thermal conductivity measurements of three samples of EG-based ZnO nanofluids have been conducted by five participating labs, four using accurate measurement apparatuses developed in house and one using a commercial device. The results have been compared with several theoretical bounds on the effective thermal conductivity of heterogeneous systems.