Experimental Study on Characteristics of Methane–Coal-Dust Mixture Explosion and Its Mitigation by Ultra-Fine Water Mist

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Hongli Xu ◽  
Xishi Wang ◽  
Rui Gu ◽  
Heping Zhang
Keyword(s):  
High Speed ◽  
Printed Circuit Board ◽  
Coal Dust ◽  
Video Camera ◽  
Water Mist ◽  
Circuit Board ◽  
Volume Flux ◽  
Coal Particles ◽  
Explosion Overpressure ◽  
Methane Concentrations

This paper presents the results of an experimental investigation on the characteristics of methane–coal-dust mixture explosion and its mitigation by ultra-fine water mist. Four E12-1-K-type fast response thermocouples, two printed circuit board (PCB) piezotronic pressure transducers were used to obtain the temperature and pressure history, while a GigaView high-speed camera was used to visualize the processes. Different methane concentrations, coal-dust concentrations, diameters of coal particles, and volumes of ultra-fine water mist were considered to investigate their effects on methane–coal-dust mixture explosion. The temperature of explosion flame, the maximum explosion overpressure, the maximum rate of overpressure rise, and the critical volume flux of ultra-fine water mist were experimentally determined. The results show that the characteristics of the methane–coal-dust mixture explosion and the mitigating effectiveness by ultra-fine water mist are influenced by the methane concentration, the coal-dust concentration, the coal-dust diameter and the applied volume flux of ultra-fine water mist. For example, both the maximum explosion overpressure and rate of overpressure rise increased with increasing of coal-dust concentrations and methane concentrations. All of the test cases indicate that ultra-fine water mist can mitigate the mixture explosion and suppress the flame propagation efficiently from the images recorded by the high-speed video camera.

Experimental Study on Characteristics of Methane-Coal Dust Mixture Explosion and Its Mitigation by Ultra-Fine Water Mist

2011 ◽  
Author(s):  
Hongli Xu ◽  
Xishi Wang ◽  
Rui Gu ◽  
Heping Zhang
Keyword(s):  
High Speed ◽  
Coal Dust ◽  
Video Camera ◽  
Fast Response ◽  
Water Mist ◽  
Volume Flux ◽  
Pressure Transducers ◽  
Coal Particles ◽  
Explosion Overpressure ◽  
Methane Concentrations

This paper presents the results of experimental investigation on characteristics of methane-coal dust mixture explosion and its mitigation by ultra-fine water mist. Four E12-1-K type fast response thermocouples, two PCB piezotronic pressure transducers were used to obtain the temperature and pressure history of methane-coal dust mixture explosion and its mitigation by ultra-fine water mist, while a GigaView High-speed camera was used to visualize the processes. Different methane concentrations, coal dust concentrations, diameters of coal particles and volumes of ultra-fine water mist were considered for their effects on methane-coal dust mixture explosion. The temperature of explosion flame, the maximum explosion overpressure, the maximum rate of overpressure rise, and the critical volume flux of ultra-fine water mist were experimentally determined. The results show that the characteristics of the methane-coal dust mixture explosion and the mitigating efficiency by ultra-fine water mist are influenced by the methane concentration, the coal dust concentration, the coal dust diameter and the applied volume flux of ultra-fine water mist. For example, both the maximum explosion overpressure and rate of overpressure rise increased with increasing of coal dust concentrations and methane concentrations. All of the test cases indicate that ultra-fine water mist can mitigate the mixture explosion and suppress the flame propagation efficiently from the images record by high speed video camera.

Design of Equivalent Sampling Based on Printed Circuit Board Suited for Power Communication System

2013 ◽  
Vol 333-335 ◽  
pp. 465-471
Author(s):  
Chuan Liu ◽  
Zhi Chao Huang ◽  
Peng Wu ◽  
Lei Chen ◽  
Wei Wang
Keyword(s):  
Time Delay ◽  
Communication System ◽  
High Speed ◽  
Printed Circuit Board ◽  
Circuit Board ◽  
Transmission Time ◽  
Clock Signal ◽  
Signal Delay ◽  
Printed Circuit ◽  
Sequential Logic

Many applications in Power communication system have a demand of adjustable transmission time delay of high-speed signal. In sequential logic circuit, the control of transmission time delay of high-speed signal can effectively improve the accuracy of clock sampling, as a result, satisfy the constraints between clock signal and periodic data. A method of equivalent sampling based on printed circuit board (PCB) is provided in the article, it realizes equivalent sampling of the data by fixing a group of clock signal delay, thus, increase the accuracy of sampling.

Optimized High Power GaN Transistors

2015 ◽  
Vol 2015 (HiTEN) ◽  
pp. 000195-000199
Author(s):  
J. Roberts ◽  
A. Mizan ◽  
L. Yushyna
Keyword(s):  
High Speed ◽  
Figure Of Merit ◽  
Printed Circuit Board ◽  
Heat Removal ◽  
Vital Role ◽  
Circuit Board ◽  
Die Structure ◽  
Power Switches ◽  
On Chip ◽  
Very High

GaN transistors intended for use at 600–900 V and that are capable of providing of 30–100 A are being introduced this year. These devices have a substantially better switching Figure-of-Merit (FOM) than silicon power switches. Rapid market acceptance is expected leading to compound annual growth rates of 85 %. However these devices present new packaging challenges. Their high speed combined with the very high current being switched demands that very low inductance packaging must be combined with highly controlled drive circuitry. While convention, and the usually vertical power device die structure, has largely determined power transistor package formats in the past, the lateral nature of the today GaN devices requires the use of new package types. The new packages have to operate at high temperatures while providing effective heat removal, low inductance, and low series resistance. Because GaN devices are lateral they require the package metal tracks to be integrated within the on-chip tracks to carry the current away from the thin on-chip metal tracks. The new GaN devices are available in two formats: one for use in embedded modular assemblies and the other for use mounted upon conventional circuit board systems. The package intended for discrete printed circuit board (PCB) assemblies has a top side cooling option that simplifies the thermal interface to the heat sink. The paper describes the die layout including the added copper tracks. The corresponding package elements that interface directly with the surface of the die play a vital role in terms of the current handling. They also provide the interface to the external busbars that allow the package to be mounted within, or on PCB. The assembly has been subject to extensive thermal analysis and the performance of a 30 A, 650 V transistor is described.

scholarly journals Multiphysics analysis of printed circuit board winding for high‐speed axial flux permanent magnet motor

2019 ◽  
Vol 13 (6) ◽  
pp. 805-811 ◽  
Author(s):  
Neethu Salim ◽  
Saurabh Prakash Nikam ◽  
Saumitra Pal ◽  
Ashok Krishnrao Wankhede ◽  
Baylon Godfrey Fernandes
Keyword(s):  
Permanent Magnet ◽  
High Speed ◽  
Printed Circuit Board ◽  
Circuit Board ◽  
Permanent Magnet Motor ◽  
Axial Flux ◽  
Printed Circuit

Evaluation of a Conductive Adhesive Based Approach to Lead Free Flip Chip Assembly

2002 ◽  
Author(s):  
Muthiah Venkateswaran ◽  
Peter Borgesen ◽  
K. Srihari
Keyword(s):  
High Speed ◽  
Flip Chip ◽  
Printed Circuit Board ◽  
Critical Evaluation ◽  
Conductive Adhesive ◽  
Circuit Board ◽  
Lead Free ◽  
Conductive Adhesives ◽  
Flip Chip Assembly ◽  
Placement Machine

Electrically conductive adhesives are emerging as a lead free, flux less, low temperature alternative to soldering in a variety of electronics and optoelectronics applications. Some of the potential benefits are obvious, but so far the adhesives have some limitations as well. The present work offers a critical evaluation of one approach to flip chip assembly, which lends itself particularly well to use with a high speed placement machine. Wafers were bumped by stencil printing of a thermoset conductive adhesive, which was then fully cured. In assembly, the conductive adhesive paste was stencil printed onto the pads of a printed circuit board and cured after die placement. The printing process was optimized to ensure robust assembly and the resulting reliability assessed.

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