Development of a Portable Polymer Electrolyte Membrane Fuel Cell System Using Metal Hydride as the Hydrogen Storage Medium

Abstract

This paper describes a Portable Polymer Electrolyte Membrane Fuel Cell (PEMFC) System developed at HySA Systems, UWC. The system has a rated maximum output power of 130 W at 240 VAC and 5 VDC USB output port. Hydrogen is supplied to the PEMFC using Metal Hydride (MH) on the basis of a multi-component AB2 – type hydrogen storage alloy (A=Ti,Zr; B=Mn,Fe,Cr,Ni; Ti:Zr=0.55:0.45). The stainless steel MH canister with external aluminium fins was developed in-house. The heat transfer performance was optimized by utilizing external fins and compacting thermal expanded graphite (TEG) with the MH powder to form pellets. The MH canister has a maximum hydrogen storage capacity of 90 NL H2. It is well-known that the endothermic desorption of H2 from MH results in the significant cooling, which decrease H2 supply flow rate. To overcome this problem and improve the dynamic performance, the MH canister was placed in front of the fuel cell exhaust to utilise the waste heat generated by PEMFC. By utilisation of the PEMFC waste heat in combination with external fins and MH / TEG compacts, the MH canister allowed for >40 minutes-long stable operation at the stack power of 130 W (225 W/kg(MH)) with the utilisation of >90% of the stored H2. Figure 1 illustrates the MH storage unit integrated with 200 W PEMFC stack, Figure 2 shows the rated power of the PEMFC and temperature of the MH canister at different loads connected to the system. Figure 1