Permeability and effective pore radius measurements for heat pipe and fuel cell applications

Permeability and effective pore radius of sintered metal powder and carbon paper samples, with specific application to fuel cells and heat pipes, were measured using the rate-of-rise test. The performance of wicks in heat pipes is characterized by effective pore radius and permeability, while the permeability measurement by itself is useful for modeling in-plane phenomena of gas diffusion layers in fuel cells. The rate-of-rise measurement technique is characterized by its simplicity and non-intrusiveness, but previous results have been considered inaccurate. In this study, the amount of liquid in the samples was measured by sight for some samples but also by weight change for other samples, which is a new adaptation of the rate-of-rise test. Data is analyzed using an equation resulting from a simple model of the rising meniscus. Knowing the behavior of the equation is important when reducing data in order to obtain more accurate results. The methods used in experimentation and data reduction demonstrate the wider use and increased accuracy of the rate-of-rise test.