Passive electrochemical hydrogen recombiner for hydrogen safety systems:prospects

This paper presents the concept of a passive electrochemical hydrogen recombiner(PEHR).The reaction energy of the recombination of hydrogen and oxygen is used as a source of electrical energy according to the operating principle for hydrogen fuel cells to establish forced circulation of the hydrogen mixture as an alternative to natural circulation(as is not utilized in conventional passive autocatalytic hydrogen recombiners currently used in nuclear power plants(NPPs)).The proposed concept of applying the physical operation principles of a PEHR based on a fuel cell simultaneously increases both productivity in terms of recombined hydrogen and the concentration threshold of flameless operation(the‘ignition’limit).Thus,it is possible to reliably ensure the hydrogen explosion safety of NPPs under all conditions,including beyond-design accidents.An experimental setup was assembled to test a laboratory sample of a membrane electrode assembly(MEA)at various hydrogen concentrations near the catalytic surfaces of the electrodes,and the corresponding current–voltage characteristics were recorded.The simplest MEA based on the Advent P1100W PBI membrane demonstrated stable performance(delivery of electrical power)over a wide range of hydrogen concentrations.

Experimental Study on Hydrogen Leakage and Emission of Fuel Cell Vehicles in Confined Spaces

Hydrogen safety is one of the most important safety indicators in fuel cell vehicles(FCVs)(unlike in other types of alternative energy vehicles).This indicator in FCVs is directly related to the user’s personal safety in daily vehicle usage.This paper analyzes the safety standards of FCVs in confined spaces.A sealed test chamber and an appropriate test method are devel-oped to evaluate vehicle safety based on specific test requirements.Two FCVs are subjected to static hydrogen leakage and hydrogen emission testing performed in a confined space.The results reveal that the hydrogen concentration in the vicinity of the vehicles approximates 0.0004%which is much lower than 1%while parked for 8 h during the hydrogen leakage test.In the hydrogen emission test under operating conditions,the concentration of the hydrogen gas emitted from the vehicles exceeds 2300 ppm in the vicinity,which requires careful consideration.Based on experiment and analysis,recommendations for the hydrogen safety standards of FCVs in confined spaces are proposed.