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QUEST (Q-shu university experiment with steady state spherical tokamak) is a midsize spherical tokamak capable of steady-state operation, comprising all-metal plasma-facing walls and a hot wall (HW) to address issues pertaining to fuel particle balance. The HW was installed summer 2014. Quantitative analysis pertaining to the HW at 373 K is carried out, and clarify the quantitative impact of shot history that obviously appears in wall stored hydrogen just before the discharge at the wall temperature. The model indicates the plasma-induced deposition layer play an essential role in fuel particle balance. A clear temperature dependence of fuel recycling was observed using outgassing just after plasma termination and played an essential role in regulation of particle balance. Consequently, long duration discharges lasting more than 1 h has been obtained at wall temperature, TW

We describe a procedure for the optimization of a 3C-SiC buffer layer for the deposition of 3C-SiC on (001) Si substrates. A 100 – 150 nm thick SiC buffer was deposited after a standard carbonization at 1125 °C, while increasing the temperature from 1125 °C to 1380 °C. Ramp time influenced the quality and the crystallinity of the buffer layer and the presence of voids at the SiC/Si interface. After the optimization of the buffer, to demonstrate its effectiveness, a high-quality 3C-SiC was grown, with excellent surface morphology, crystallinity and low stress.

[Synopsis] It is important to clarify evaporation characteristic of liquid fuel such as gasoline and diesel fuel. This study was conducted on evaporation phenomena of a fuel droplet on a hot wall. Several kinds of alcoholic addition fuel were used as the test. The influence alcoholic addition fuel affect evaporation life time was investigated in detail.

Analysis has been carried out for energy distribution and thermal mixing in steady laminar natural convective flow through the porous rhombic cavities with inclination angle ? for various applications such as geothermal, grain storage, electronic cooling, etc. A generalized non-Darcy model without the Forchheimer inertia term is used to predict the flow in porous media. The effect of the Darcy number (Da) and the role of ? on the energy distribution and thermal mixing within porous rhombic cavities with isothermal (case 1) and nonisothermal (case 2) hot bottom walls are illustrated via " heatlines". Heat transfer is found to be primarily conduction dominant at Da = 10 -5 even at a higher Rayleigh number (Ra = 10 6). The onset of convection occurs at Da = 10 -4, and the distorted heatlines from the hot bottom wall take a longer path to reach the cold side walls of the cavity. Larger heat transfer and thermal mixing occurs for Da = 10 -3 at Ra = 10 6 irrespective of ? and Pr. Multiple flow/convective circulations are observed at Pr = 0.015 for all ? values at Da = 10 -3. On the other hand, two asymmetric flow circulation cells are found to occupy the entire cavity at Pr = 0.7, 7.2, and 1000 for ? = 75� at Da = 10 -3. The cavity with inclination angle ? = 30� enhances the convective heat transfer from the hot wall to the cold wall, and the heat transfer to the right cold wall is a maximum for ? = 75�, as depicted by "heatlines" irrespective of Pr at Da = 10 -3. Average Nusselt number studies based on heatfunction gradients also show that the cavity with ? = 30� gives a maximum heat-transfer rate from the bottom to the left wall irrespective of Pr in case 1 at Da = 10 -3. The cup mixing temperature (? cup) is higher for case 1 compared to case 2, and it is almost invariant with ? for higher Pr (Pr = 7.2 and 1000) in case 1 at Da = 10 -3. � 2011 American Chemical Society.

Electrowetting (EW) involves the actuation of liquid droplets using electric fields and has been demonstrated as a powerful tool for initiating and controlling droplet-based microfluidic operations such as droplet transport, generation, splitting, merging and mixing. The heat transfer resulting from EW-induced droplet actuation has, however, remained largely unexplored owing to several challenges underlying even simple thermal analyses and experiments. In the present work, the heat dissipation capacity of actuated droplets is quantified through detailed modeling and experimental efforts. The modeling involves three-dimensional transient numerical simulations of a droplet moving under the action of gravity or EW on a single heated plate and between two parallel plates. Temperature profiles and heat transfer coefficients associated with the droplet motion are determined. The influence of droplet velocity and geometry on the heat transfer coefficients is parametrically analyzed. Convection patterns in the fluid are found to strongly influence thermal transport and the heat dissipation capacity of droplet-based systems. The numerical model is validated against experimental measurements of the heat dissipation capacity of a droplet sliding on an inclined hot surface. Infrared thermography is employed to measure the transient temperature distribution on the surface during droplet motion. The results provide the first in-depth analysis of the heat dissipation capacity of electrowetting-based cooling systems and form the basis for the design of novel microelectronics cooling and other heat transfer applications. (C) 2011 Elsevier Ltd. All rights reserved.

It is important to clarify evaporation characteristic of liquid fuel such as gasoline and diesel fuel. This study was conducted on evaporation phenomena of a fuel droplet on a hot wall. Several kinds of liquid normal-paraffin such as n-Hexane, Cyclohexane, Benzene were used as the test. The influence molecular structure of fuel affect evaporation lifetime was investigated in detail.

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Conjugate natural convection finds various thermal applications in chemical industries, where the heat transfer is controlled by the presence of solid walls such as heat exchanger, nuclear reactors, fin type cooling and solar storage systems. Heat flow distribution within square cavity enclosed by vertical conducting walls of definite thickness ( t 1 and t 2 ) is analyzed for various fluids (Pr) in this study based on the location of the wall thickness [left wall (case 1)/ right wall (case 2)/ both side walls (case 3)] and conductivity ratios between solid and fluid regions ( K ). At Ra = 10 5 , circular heatlines are observed near core of the cavity at K =0.1 whereas they are distorted and pushed towards the hot wall at K =10 with low Pr ( Pr =0.015). On the other hand, heatlines are horizontally stretched at core of the cavity for higher Pr ( Pr =0.7 and 1000) at K =10. End to end heatlines are highly compressed near top portion of the cavity at K =10 irrespective of Pr. Closed loop heatlines are absent for case 2 at Ra = 10 3 whereas closed loop heatlines with lesser magnitude than cases 1 and 3 are observed for case 2 at Ra = 10 5 due to less heat transfer from the hot solid wall irrespective of Pr at K =0.1 and 1. The heat transfer rate can be maintained constant at low thermal conductivity ratio ( K ) even for the high convective regime ( Ra = 10 5 ) irrespective of wall thickness ( t 1 and t 2 ). Average Nusselt number shows overall larger heat transfer rate for higher K ( K =10), which is almost identical with classical natural convection (zero wall thickness) compared to lower K ( K =0.1 and 1) irrespective of location of wall thickness (cases 1–3). In order to achieve almost invariant or lower fluid temperature at Ra = 10 5 for t 1 + t 2 = 0.2 and 0.8, solid wall at hot side (case 2) may be useful. This heating strategy may be viewed for high temperature shielding or minimization of thermal runaway for temperature sensitive applications, such as environmental control system, chemical storage reservoirs, etc., where heat flow is controlled by solid wall resistance.

This article analyzes the detailed heat transfer phenomena during natural convection within tilted square cavities with isothermally cooled walls (BC and DA) and hot wall AB is parallel to the insulated wall CD. A penalty finite element analysis with bi-quadratic elements has been used to investigate the results in terms of streamlines, isotherms and heatlines. The present numerical procedure is performed over a wide range of parameters (10 3 ⩽ Ra ⩽ 10 5 ,0.015 ⩽ Pr ⩽ 1000,0° ⩽ φ ⩽ 90°). Secondary circulations cells are observed near corner regions of cavity for all φ ’s at Pr = 0.015 with Ra = 10 5 . Two asymmetric flow circulation cells are found to occupy the entire cavity for φ = 15° at Pr = 0.7 and Pr = 1000 with Ra = 10 5 . Heatlines indicate that the cavity with inclination angle φ = 15° corresponds to large convective heat transfer from the wall AB to wall DA whereas the heat transfer to wall BC is maximum for φ = 75°. Heat transfer rates along the walls are obtained in terms of local and average Nusselt numbers and they are explained based on gradients of heatfunctions. Average Nusselt number distributions show that heat transfer rate along wall DA is larger for lower inclination angle ( φ = 15°) whereas maximum heat transfer rate along wall BC occur for higher inclination angle ( φ = 75°).

Bejan's heatlines approach has been introduced to visualize heat flow during natural convection within a tilted square cavity inclined at an angle of ?=30�. The enclosure is bounded by hot wall AB (case 1: isothermal heating and case 2: nonisothermal heating), isothermally cooled walls DA and BC in the presence of adiabatic wall CD. The results are presented in terms of streamlines, isotherms, heatlines, and local and average Nusselt numbers. The nonisothermal heating case produces the greater heat transfer rate at the center of the wall AB compared to that of the isothermal heating case, whereas the average Nusselt number shows an overall lower heat transfer rate for the nonisothermal heating case. � 2012 Copyright Taylor and Francis Group, LLC.

In this article, the numerical investigation of entropy generation due to heat transfer irreversibility and fluid friction irreversibility during natural convection within tilted square cavity with hot wall AB, cold side walls (DA and BC), and top insulated wall (CD) has been performed. The numerical simulation has been carried out for various fluids of industrial importance (Pr = 0.015, 0.7, and 1000), Rayleigh numbers (10 3 ? Ra ? 10 5), and different inclination angles (f = 15�, 45�, and 75�). The results are presented in terms of isotherms streamlines, entropy generation maps due to heat transfer (S?), and fluid friction (S). The total entropy generation (S total), average Bejan number (Beav), and average heat transfer rate (NuAB) are plotted for Rayleigh number 10 3 ? Ra ? 10 5. The maximum values of S? occur near the corner regions of wall AB due to a junction of hot and cold walls. On the other hand, maximum values of S? are found near the walls of the cavity due to friction between the circulation cells and walls of the cavity. It is found that minimum entropy generation occurs for f= 45� at convection dominant mode (Ra = 10 5) for lower Pr (Pr = 0.015 and 0.7). The inclined cavity with = 45� may be an alternative optimal inclination angle in optimal thermal processing of high Pr (Pr = 1000). � 2012 American Chemical Society.

Chromium carbide coatings were grown at 748 K in a hot wall CVD reactor fed by sublimation of bis(benzene)chromium, BBC (MOCVD) and by direct liquid injection using a BBC/toluene solution (DLICVD). The two types of coatings exhibit an amorphous structure and the same C content (22 at.%). DLICVD permits delivering higher mass flow rate of precursors and consequently the growth rate is 3 times higher and the thickness uniformity is better than using MOCVD. Chromium metal deposition has also been investigated by DLICVD in this hot wall reactor using BBC/toluene/additive as precursor. The purpose of the additive is to block carbide formation. Two additives have been studied: (i) hexachlorobenzene (C6Cl65 and (ii) thiophenol (C6H5SH). The ratio additive/BBC required for Cr metal deposition is a few percent. In this process, C6Cl6 is not decomposed and only traces of Cl (0.4 at.%) are found in the coatings. For a ratio C6Cl6/BBC > 27% the growth of any coating is blocked. The gas phase containing C6H5SH is more reactive since the onset of deposition occurs approximately 50 K before the temperature of the chlorinated compound. Furthermore, a sulfur contamination of 3 at.% has been analyzed in the coatings revealing a partial decomposition of the additive. The results are detailed and discussed in relation with previous works.

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An experimental study was conducted on the evaporation and combustion phenomena of a single fuel drop in ambient gas pressurized and heated beyond the critical point of fuel, that is, supercritical environments on a hot wall. Several kinds of liquid paraffin such as n-heptane, n-decane, n-dodecane and n-tetradecane were used as the test fuel. The evaporation lifetime in air was found to be shorter than that in nitrogen at the same wall temperature. The difference in the evaporation lifetimes in air and nitrogen environments was greater under higher ambient pressure for the same fuel ; for the same ambient pressure, it was greater under a larger ratio of ambient pressure to critical pressure of the fuel. As ambient pressure increased from subcritical to supercritical pressure, the end of combustion time increased in the wall temperature range around the critical temperature of the fuel, whereas in a wall temperature range higher than the critical temperature of the fuel, it decreased.

An experimental study was conducted on the evaporation and combustion phenomena of a single n-dodecane drop in ambient gas pressurized and heated beyond the critical point of fuel, that is, supercritical environments produced on a hot wall. The evaporation lifetime in air at the wall temperature below the ignition temperature was found to be shorter than that in nitrogen at the same wall temperature. The end of combustion time in air at ambient pressure below the critical pressure of the fuel was correlated with the evaporation lifetime, and it was maximum in the wall temperature range where the drop showed spheroidal evaporation. As the ambient pressure increased beyond the critical pressure of the fuel, the end of combustion time increased in the wall temperature range around the critical temperature of the fuel, and in other wall temperature ranges, it decreased.