Lower Channel Flow Research Articles

Study on the thermal dissipation performance of GPU cooling system with nanofluid as coolant

The graphic processing unit is the active component that is an important heat source in electronic devices. The GPU cooling system's thermal dissipation performance with de-ionized water and nanofluid as coolants are presented. In the experiment, the GPU cooling system was embedded with the personal computer's GPU board, which in the overclock operating condition. The Ag nanofluid with 0.015% by volume concentration and de-ionized water is used as coolants flowing in the cooling system, considering the effects of coolant types and heat sink configurations on the thermal resistance. It found that the nanoparticles suspending in the base fluid significantly impact the nanofluid's physical properties and flow features, which results in higher removal capacity and, consequently, lower thermal resistance. The heat sink with a lower flow channel gives lower thermal resistance than those from higher ones. The results from this work have been used to develop a knowledge base that can be used to a design-related thermal cooling system for GPU or other components of electronic devices.

In-line phase separator for microfluidic solvent extraction of uranium

Experiments are carried out to study the separation of liquid-liquid dispersion generated at a microfluidic junction by using an in-line phase separator. The phase separator comprises a metallic mesh sandwiched between two flow channels. Dispersion generated at the microfluidic junction is fed to the upper flow channel of the in-line phase separator. Continuous phase permeates through the metallic mesh into the lower flow channel and gets separated from the dispersed phase. The effects of operating parameters (flow rates of the aqueous and organic phases), flow channel geometry and mesh properties (pore size and thickness) on phase separation are studied. After identification of operating window in which complete phase separation is achieved, mass transfer experiments are performed to demonstrate intensified uranium extraction using a micromixer and in-line phase separator.

Timing and rate of exhumation along the Litang fault system, implication for fault reorganization in Southeast Tibet

The Litang fault system that crosses the Litang Plateau, a low relief surface at high elevation (~4200–4800 m above sea level) that is not affected by regional incision, provides the opportunity to study exhumation related to tectonics in the SE Tibetan Plateau independently of regional erosion. Combining apatite and zircon fission track with apatite (U-Th)/He thermochronologic data, we constrain the cooling history of the Litang fault system footwall along two transects. Apatite fission track ages range from 4 to 16 Ma, AHe ages from 2 to 6 Ma, and one zircon fission track age is ~99 Ma. These data imply a tectonic quiet period sustained since at least 100 Ma with a slow denudation rate of ~0.03 km/Ma, interrupted at 7 to 5 Ma by exhumation at a rate between 0.59 and 0.99 km/Ma. We relate that faster exhumation to the onset of motion along the left-lateral/normal Litang fault system. That onset is linked to a Lower Miocene important kinematic reorganization between the Xianshuihe and the Red River faults, with the eastward propagation of the Xianshuihe fault along the Xiaojiang fault system and the formation of the Zhongdian fault. Such strike-slip faults allow the sliding to the east of a wide continental block, with the Litang fault system accommodating differential motion between rigid blocks. The regional evolution appears to be guided by the strike-slip faults, with different phases of deformation, which appears more in agreement with an “hidden plate-tectonic” model rather than with a “lower channel flow” model.

Field observations of the June 30, 2001 debris flow at Acquabona (Dolomites, Italy)

On June 30, 2001, a debris flow occurred in the Acquabona Creek, a small catchment of the Eastern Dolomites, Italy. This debris flow originated shortly after an intense rainstorm, characterised by a peak intensity of 8.6 mm per 10 min; it transported a total volume of 30,000 m3, consisting of poorly sorted gravely sand with boulders up to 3 m in diameter. The sediment erosion yield rate reached as high as 20 m3/m. In order to verify the accuracy of the field measurements, the total volume of debris deposits have was calculated using three different topographic measurement techniques: 3D laser scanning, terrestrial stereo-photogrammetry survey and total topographic station survey. Data collected so far show that no debris flow has occurred at Acquabona with a rainfall intensity lower than 4.6 mm per 10 min. Channel cross section measurements indicate that debris flow velocity ranges from 2.0 to 7.2 m/s along the lower flow channel and peak discharge ranges between 22 and 300 m3/s. Field estimates of the rheological properties indicate a yield strength ranging from 2,088 to 5,313 Pa and Bingham viscosity between 70 and 337 Pa · s. It is not still possible to identify a rainfall intensity and amount threshold for debris flow triggering, but the data so far collected emphasise that debris flows do not occur with a rainfall intensity lower than 4.6 mm per 10 min.

NUMERICAL STUDY ON HEAT TRANSFER CHARACTERISTICS AND PERFORMANCE OF DOUBLE-PASS FLAT PLATE SOLAR AIR HEATERS

In this study, the flow and heat transfer characteristics and the performance of double-pass flat-plate solar air heaters are studied numerically. The effects of the total air mass flow rate and the fraction of air mass flow rate in the upper or lower flow channel on the performance of the double-pass flat-plate solar air heaters have also been investigated numerically. The mathematical models that describe the flow and heat transfer characteristics of the double-pass flat-plate solar air heaters are derived from the momentum and energy conservation equations. The developed mathematical model has been solved using a finite volume discrete scheme utilizing the SIMPLE (Semi-Implicit Method for Pressure Linked Equations) pressure-correction scheme combined with QUICK (Quadratic Upwind Interpolation Convective Kinematics) scheme in the frame of staggered system. The results obtained from the numerical model are validated by comparison with experimental data of previous researchers. It has been found that there is a reasonable agreement between the present model results and those obtained by previous investigators.