The performance of a single spray for electronic power devices using deionized (DI) water and pure silver (Ag) particles as well as multi-walled carbon nanotube (MCNT) particles, respectively, is studied herein. The tests are performed with a flat horizontal heated surface using a nozzle diameter of 0.5 mm with a definite nozzle-to-target surface distance of 25 mm. The effects of nanoparticle v...

In-tube flow boiling at low mass and heat fluxes is of increasing interest particularly for low-concentration solar power systems, refrigerators, pumps, other thermal management components systems. In this study, the R-245fa was investigated experimentally vapour qualities ranging from 0.05 to 0.90, 40, 60 80 kg/m 2 s, 2.5, 5.0 7.5 kW/m . Tests were done quasi-steady-state conditions in a horiz...

0017-9310/$ see front matter 2009 Elsevier Ltd. A doi:10.1016/j.ijheatmasstransfer.2009.09.035 * Corresponding author. Tel.: +1 860 654 9325; fax E-mail address: [email protected] (G. Qui An experimental study was conducted to investigate how the addition of small amounts of a surfactant influences the heat transfer characteristics in a thin boiling liquid film flowing in a diverging ope...

The effects on pool boiling characteristics such as critical heat flux and the heat transfer coefficient of different surface characteristics such as surface wettability, roughness, morphology, and porosity are not well understood. Layer-by-layer nanoparticle coatings were used to modify the surface of a sapphire heater to control the surface roughness, the layer thickness, and the surface chem...

abstract: in this study, al 2 o 3 /eg and tio 2 /eg nanofluids as coolants have been used in the double-tube heat exchanger. the hot solvent inlet heat exchanger must be cooled down with a specified amount. we can use nanofluids as coolants in the heat exchanger for optimization of the heat transfer area. therefore, the efficacy of nanofluids as coolants is verified. furthermore, flow rate of c...

Phase change heat transfer is fundamentally important for thermal energy conversion and management, such as in electronics with power density over 1 kW/cm^2. The critical heat flux (CHF) of phase change heat transfer, either evaporation or boiling, is limited by vapor flux from the liquid-vapor interface, known as the upper limit of heat flux. This limit could in theory be greater than 1 kW/cm2...

bubble columns are gas- liquid contactors that are widely used in chemical and bio- chemical industries. high mixing that result in high heat and mass transfer rates are amongst their advantages. heat transfer in a bubble column having a bundle of heaters investigated and the variation of heat transfer coefficient with variation in heaters pitch to diameter ratios in a bundle of heaters reporte...

As is well known, boiling is an effective mode of heat transfer in that high heat flux levels are possible with relatively small temperature differences. Its optimal application requires that the process be adequately understood. A measure of the understanding of any physical event lies in the ability to predict its behavior in terms of the relevant paramem. Despite many years of research the p...

Pool boiling heat transfer measurements from different heater sizes were obtained in low-g (0.01± 0.025 g) and high-g (1.7 ± 0.5 g) aboard the KC-135 aircraft. Boiling on three heaters of different size (0.65, 2.62, 7.29 mm) was studied. Control circuitry was used to maintain an isothermal boundary condition on the heater surface while the power dissipated by the heater was measured. Steadystat...