Passive dual-phase cooling for fuel cell assemblies

Abstract

A cooling apparatus for a fuel cell assembly includes a heat transfer fluid and at least one fluid flow field plate configured to facilitate essentially passive, two-phase cooling for an membrane electrode assembly (MEA) as the MEA is subject to changes in heat flux to the heat transfer fluid from about 0 W / cm<2> to about 1.5 W / cm<2>. The flow field plate includes fluid flow channels that have a channel depth, a channel spacing, a channel length, and a channel width, which are dimensioned to promote nucleated boiling of the heat transfer fluid below a critical heat flux and to prevent dryout as the heat transfer fluid passes along the length of the channels. The channels may include coatings and / or features, such as microporous or nanostructured coatings, that extend the critical heat flux and preclude dryout at the distal sections of the fluid flow channels.

Description

technical field [0001] The present invention generally relates to passive two-phase cooling apparatus and methods for fuel cell components and assemblies in a fuel cell stack. Background technique [0002] A typical fuel cell system includes an energy section in which one or more fuel cells generate electrical energy. Fuel cells are energy conversion devices that convert hydrogen and oxygen into water, while generating electricity and heat in the process. Each fuel cell unit may include a centrally located proton exchange member with a gas diffusion layer on each side of the proton exchange member. An anode catalyst layer and a cathode catalyst layer are respectively arranged inside the gas diffusion layer. This type of fuel cell is commonly referred to as a PEM fuel cell. [0003] The reaction in a single fuel cell typically produces a voltage of less than one volt. Multiple fuel cells can be stacked and electrically connected in series to achieve a desired voltage. El...

AI Technical Summary

Problems solved by technology

[0005] This single-phase technology has several significant disadvantages, including, for example, the need for pumps, piping, large volumes of heat transfer fluid, and effective control during start-up to regulate the temperature of the stack, or to accommodate changes in heat output and environmental conditions, resulting in Added weight and cost

The electrical energy consumed by the pump must be provided by the stack and dissipated by its thermal system, thus reducing available energy and increasing the size of the primary heat exchanger

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