Compression of seals in PEM fuel cells

Abstract

Seals or gaskets are used in PEM fuel cells (PEMFC) or stacks to prevent leaking of the liquid and gas inside the cell. The fuel cells or the stacks are normally assembled with nuts and bolts or a combination of nuts, bolts, and springs. As the seal is typically made of polymers, the level of the compressive stress applied to the seal during long term operation of the fuel cell relaxes. In addition, the amount of compression applied to the seal may vary due to temperature changes during the fuel cell operation which arises from thermal expansion and contraction of all components in the cell. To understand the sealing force existed in a fuel cell during operation, all these factors must be fully understood. In this study, the compression of the seal in a PEMFC was investigated experimentally. Specifically the amount of compression was measured in-situ, i.e. immediately after the assembly and during the normal operation of the PEMFC. The objective of this study is to gain an understanding of the variation of compressive strain applied to the seal as the temperature of the PEMFC changes and cycles. This information is useful in estimating the sealing force in the cell and consequently the life of the seal. ©2010 Society for Experimental Mechanics Inc.