DOI QR코드

DOI QR Code

Friction Factor in Micro Channel Flow with Electrochemical Reactions in Fuel Cell

전기화학반응을 수반한 유로채널 형상에 따른 마찰계수에 대한 연구

  • Published : 2007.11.28

Abstract

The performance of fuel cell is enhanced with increasing reaction surface. Narrow flow channels in flow plate cause increased pumping power. Therefore it is very important to consider the pressure drops in the flow channel of fuel cell. Previous research for pressure drop for micro channel of fuel cell was focused on effects of various configuration of flow channel without electrochemical reaction. It is very important to know pressure loss of micro flow channel with electrochemical reaction because fluid density in micro channel is changed due to chemical reaction. In this paper, it is investigated that the pressure drops in micro channel of various geometries at anode and cathode with electrochemical reaction and compared them to friction coefficient (fRe), velocity, pressure losses for corresponding non reacting flow channel. The results show that friction factors for cold flow channel could be used for parallel and bended flow channel for flow channel design of fuel cell. In the other hand, pressure drop for serpentine flow channel is the lowest among flow channels due to bypass flow across gas diffusion layer under reacting flow condition although its pressure drop is highest for cold flow condition.

주어진 연료전지면적에서 반응면적이 넓을수록 성능이 향상되는 연료전지는 좁은 폭의 채널을 여러 개 존재하게 하는 구조를 선호하지만 채널 폭이 좁아질수록 압력이 커지는 문제가 고려되어져야 한다. 그러나 현재 채널 구조에 따른 압력에 대한 연구는 많이 진행되어져 왔지만 대부분 반응을 고려하지 않았으며, 반응을 고려한 경우에 어떤 경향을 나타내는지 알아보는 것이 연료전지 유로설계에 있어 매우 중요하다. 본 논문에서 화학반응을 고려한 평행류, 90도 밴드형, serpentine 세가지 종류의 유로채널를 가진 연료전지를 수치 해석하여 반응을 고려하지 않은 경우와 마찰계수(fRe), 속도, 압력강하를 비교하여 본 결과 parallel과 bend 형태의 채널은 반응을 고려한 경우 반응에 의한 밀도의 감소에 따라 근소하게 감소한 것을 알 수 있었다. 그러나 serpentine채널은 다공성매체인 확산층을 통해 인접한 채널로 가스가 이동하는 bypass flow 영향에 의하여 상대적으로 낮은 압력강하를 나타내는 것을 알 수 있었다.

Keywords

References

  1. J. A. C. Humphrey, J. H. Whitelaw, G. Yee, 'Turbulent Flow in a Square Duct with Strong Curvature' J. Fluid Mech.103, 443(1981) https://doi.org/10.1017/S0022112081001419
  2. Y. Miyaka, T. Kazishima, T. Inaba, 'International Conference on Experimental Heat Transfer' Fluid Mechanics and Thermodynamics, (1988)
  3. A. J. Ward-Smith, 'Internal Fluid Flow, Oxford university press' New York, (1980)
  4. S. Maharudrayya, S. Jayanti, A. P. Deshpande, 'Pressure losses in laminar flow through serpentine channels in fuel cell stacks' J. Power Sources 138, 1(2004) https://doi.org/10.1016/j.jpowsour.2004.06.025
  5. A. S. Rawool, S. K. Mitra, A. Agrawal, S. Kandikar, 'Numerical simulation of flow through microchannels in bipolar plate' ICMM2005-75251, (2005)
  6. J. G. Pharoah, 'On the permeability of gas diffusion media used in PEM fuel cells' J. Power sources 144, 77(2005) https://doi.org/10.1016/j.jpowsour.2004.11.069
  7. Lan Sun, Patrick H. Oosthuizen, Kim B. McAuley, 'A numerical study of channel-to-channel flow cross-over through the gas diffusion layer in a PEM-fuel-cell flow system using a serpentine channel with a trapezoidal cross-sectional shape' Int. J. Thermal Sciences 45, 1021(2006) https://doi.org/10.1016/j.ijthermalsci.2006.01.005
  8. Jinliang Yuan, Masoud Rokni, and Bengt Sunden, 'A numerical investigation of gas flow and heat transfer in proton exchange membrane fuel cells' Num. Heat Transfer(partA) 44, 255(2003) https://doi.org/10.1080/716100507
  9. A. S. Rawool, Sushanta K. Mitra, Jon G. Pharoah, 'An investigation of convective transport in micro proton-exchange membrane fuel cells' J. Power Source 162, 985(2006) https://doi.org/10.1016/j.jpowsour.2006.07.067
  10. R. Bird, W. Stewart, E. Lightfoot, 'Transport phenomena' Wiley, New York, (1960)
  11. J. Park, X. Li, 'Experimental and Numerical Investigation of Reaction Flow in Flow Channels and Leakage Cross Flow Through Gas Diffusion Layers in PEM Fuel Cells' Fuel Cell Seminar, Hawaii, (2006)