Study of a thermal bridging approach using heat pipes for simultaneous fuel cell cooling and metal hydride hydrogen discharge rate enhancement

Low hydrogen discharge rate of Metal Hydride (MH) hydrogen canisters is a common challenge for this type of storage when used to supply hydrogen to Proton Exchange Membrane (PEM) fuel cells. The present paper investigates the use of fuel cell heat, transferred using heat pipes, to enhance the hydrogen release rate of MH canisters. Both the theoretical models and the experimental study on a 130-W PEM fuel cell supplied by an 800-sl MH canister (used as a case study), confirmed that ∼30% of the fuel cell cooling load is sufficient to maintained the temperature of the canister at ∼25 °C, required for the MH canister to supply hydrogen at 1.7 slpm (as demanded by the fuel cell for operation at 130 W). Using additional heat pipes (i.e. to remove the remaining ∼70% the fuel cell cooling load), the temperature of the fuel cell could be maintained at ∼60 °C. The study also confirmed that this thermal management system can deliver relatively uniform temperature distributions across the stack and the MH canister with less than 5 °C of temperature gradient across these components.