Micro-electro-mechanical systems (MEMS) and nano-electro-mechanical systems (NEMS) have become the focus of a great deal of attention in recent years. The flow and heat behaviors of micro-machines are usually different from that of macro-machines. In this paper, the heat and mass transfer characteristics of rarefied nitrogen gas flows in microchannels have been investigated using improved DSMC method. The influence of aspect ratio and wall temperature on the mass flowrate and wall heat flux in microchannels are studied parametrically. In order to examine the aspect ratio effect on heat and mass transfer, the wall temperature is set constant at 350 K, and the aspect ratio of the microchannel varies from 5 to 20. The results show that as the aspect ratio increases, the velocity of the flow decreases, and the mass flowrate also decreases. In a small aspect ratio channel, the heat transfer occurs throughout the microchannel, and as the aspect ratio of the microchannel increases, the region of thermal equilibrium becomes larger. To investigate the effects of wall temperature on heat and mass transfer, the aspect ratio of the microchannel is held constant at 10 and the wall temperature is changed from 300 K to 800 K. The results show that, when the wall temperature increases, the pressure increases slightly and the number density drops rapidly near the inlet. In addition, the Knudsen number increases as the wall temperature increases. It indicates that the increasing wall temperature of microchannel enhances the rarefaction of the gas flow. Moreover, as the wall temperature increases, the mass flowrate decreases, and the temperature will increase more rapidly near the inlet, with more heat transfer between the gas flow and the wall.
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ASME 2008 International Mechanical Engineering Congress and Exposition
October 31–November 6, 2008
Boston, Massachusetts, USA
Conference Sponsors:
- ASME
ISBN:
978-0-7918-4871-5
PROCEEDINGS PAPER
Using Improved DSMC Method in Simulating for the Heat and Mass Transfer in Microchannels Available to Purchase
J. Y. Zheng,
J. Y. Zheng
Zhejiang University, Hangzhou, China
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W. Z. Li,
W. Z. Li
Dalian University of Technology, Dalian, China
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C. K. Lam,
C. K. Lam
University of California - Berkeley, Berkeley, CA
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M. McKenna,
M. McKenna
University of California - Berkeley, Berkeley, CA
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Y. B. Ma
Y. B. Ma
University of California - Los Angeles, Los Angeles, CA
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J. J. Ye
Zhejiang University, Hangzhou, China
J. Yang
Zhejiang University, Hangzhou, China
P. Tang
Zhejiang University, Hangzhou, China
J. Y. Zheng
Zhejiang University, Hangzhou, China
W. Z. Li
Dalian University of Technology, Dalian, China
C. K. Lam
University of California - Berkeley, Berkeley, CA
M. McKenna
University of California - Berkeley, Berkeley, CA
Y. B. Ma
University of California - Los Angeles, Los Angeles, CA
Paper No:
IMECE2008-66915, pp. 1507-1514; 8 pages
Published Online:
August 26, 2009
Citation
Ye, JJ, Yang, J, Tang, P, Zheng, JY, Li, WZ, Lam, CK, McKenna, M, & Ma, YB. "Using Improved DSMC Method in Simulating for the Heat and Mass Transfer in Microchannels." Proceedings of the ASME 2008 International Mechanical Engineering Congress and Exposition. Volume 10: Heat Transfer, Fluid Flows, and Thermal Systems, Parts A, B, and C. Boston, Massachusetts, USA. October 31–November 6, 2008. pp. 1507-1514. ASME. https://doi.org/10.1115/IMECE2008-66915
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