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Thermal Interaction (thermal + interaction)

Distribution by Scientific Domains

Engineering	75%

Selected Abstracts

Numerical simulation of thermal interaction between polymer and argon induction thermal plasma

ELECTRONICS & COMMUNICATIONS IN JAPAN, Issue 1 2009
Yoshitaka Takeuchi
Abstract Influence of polymer powder injection into Ar thermal plasmas was investigated by numerical approaches. Thermal plasma,polymer solid coupling phenomena such as melting and evaporation were considered to study plasma-quenching effect of polymer injection. Dominant process for decay of plasma temperature was examined by changing thermodynamic parameters such as melting, boiling temperatures and their latent heats of solid and liquid polymers. As a result, thermodynamic properties of evaporated polymer vapor directly affect plasma-quenching phenomena more markedly than the properties of liquid and solid which influence plasma quenching efficiency through the amount of evaporation. © 2009 Wiley Periodicals, Inc. Electron Comm Jpn, 92(1): 24,33, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10226 [source]

Observations of initiation stage of spontaneous vapor explosions for droplet scale

HEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 1 2008
Takeo Takashima
Abstract In this study, the initiation stage of spontaneous vapor explosions generated by single droplets of molten tin submerged in water was investigated using a high- speed video camera operated with a reflected light system. Photographs of the formation process of vapor film, the process of vapor film disturbance, and the initiation process of the vapor explosions for different masses of molten tin and different nozzle diameters were obtained. The results demonstrate that partial thermal interaction between tin and water does not cause a vapor explosion with fragmentation. The vapor film disappears locally during the formation of the vapor film around the hot liquid droplet. Direct contact between the hot molten tin surface and water is thereby generated. However, the local disappearance of the vapor film does not progress and the vapor film is reconstructed. A vapor explosion occurs when the vapor film collapses at the local area of the bottom or edge of the disk-shaped droplet. © 2007 Wiley Periodicals, Inc. Heat Trans Asian Res, 37(1): 41,55, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20185 [source]

Electrothermal model of optocoupler for SPICE

INTERNATIONAL JOURNAL OF NUMERICAL MODELLING: ELECTRONIC NETWORKS, DEVICES AND FIELDS, Issue 4 2009
Krzysztof Górecki
Abstract In the paper a new electrothermal model of the optocoupler for SPICE is proposed. The model is based on electrical models of the LED and the bipolar phototransistor with their parameters dependent on temperature, their thermal models including both the self-heating phenomenon and the mutual thermal interactions between the LED and the phototransistor, and the dependences describing electrical power dissipated in these components. The final form of the electrothermal model of the optocoupler elaborated by the authors, dedicated to the d.c. and a.c. computations, was implemented in SPICE. The usefulness of the new model was experimentally verified for the optocoupler 4N25. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Modeling of rotational molding process: Multi-layer slip-flow model, phase-change, and warpage

POLYMER ENGINEERING & SCIENCE, Issue 7 2006
K.K. Lim
A new multilayer slip-flow model has been developed to simplify and to overcome current numerical difficulties of two-dimensional model in predicting the internal air temperature inside a mold during a rotational molding process. The proposed methodology considers a macroscopic "layer-by-layer" deposition of a heating polymer bed onto the inner mold surface. A semi-implicit approach is introduced and applied to compute the complex thermal interactions between the internal air and its surroundings. In the model, the lumped-parameter system and the coincident node technique are incorporated with the Galerkin finite element model to address the internal air and the deposition of molten polymer beds, respectively. The simple phase-change algorithm has been proposed to improve the computational cost, numerical nonlinearity, and predicted results. The thermal aspects of the inherent warpage are explored to study its correlation to the weak apparent crystallization-induced plateau in the temperature profile of the internal air, as in practice. The overall predicted results are in favor with the available experimental data for rotomolded parts of cross-sectional thicknesses up to 12 mm. POLYM. ENG. SCI. 46:960,969, 2006. © 2006 Society of Plastics Engineers [source]