How a Fuel Cell Humidifier Safely Mixes Exhaust Gases

Hyundai's patent describes a fuel cell humidifier that not only adds moisture to incoming air but also intelligently mixes exhaust gases, including hydrogen, with fresh air using a special valve to make the exhaust safer before it leaves the system.

What it covers

This humidifier prepares air for a fuel cell by passing "supply air" through a "humidifying membrane" (Claim 1), which adds moisture. The humidified air then goes to the fuel cell's cathode. Crucially, the system includes a "first valve" (Claim 1) that can selectively connect the fresh air path with the exhaust gas path. This valve opens automatically when the "internal pressure of the second region" (Claim 2), where exhaust gas flows, reaches a certain level. When open, fresh "supply air" mixes with the "exhaust gas" (Claim 1) from the fuel cell, including "exhaust hydrogen" (Claim 2). This mixing reduces the "hydrogen concentration" (Claim 2) in the gas discharged to the exhaust system, enhancing safety. For example, if a fuel cell vehicle produces hydrogen-rich exhaust, this system can dilute it with fresh air before release.

What it doesn't cover

• —Humidifiers that do not include a valve for selective communication between the supply air region and the exhaust gas region (Claim 1).
• —Systems where the valve does not open due to the internal pressure of the exhaust gas region (Claim 2).
• —Humidifiers that do not mix supply air with exhaust gas to specifically reduce hydrogen concentration (Claim 2).
• —Humidifiers lacking a separate, pressure-operated valve for exhaust hydrogen introduced from the fuel cell anode (Claim 10).
• —Humidifiers where the first valve is not installed between the first cap and the exhaust gas outlet (Claim 3).

The clever bit

The core innovation is the "first valve" (Claim 1) that provides selective communication between the fresh air supply and the exhaust gas path. This valve is designed to open automatically based on exhaust gas pressure (Claim 2), enabling the system to actively mix fresh air with exhaust to reduce hazardous hydrogen concentrations before discharge.

Why it matters

Fuel cells require humidified air to operate efficiently and prevent their internal membranes from drying out. Beyond efficiency, managing exhaust gases, particularly hydrogen, is vital for safety in fuel cell applications like vehicles. This patent addresses both the performance need for humidification and the critical safety requirement of diluting potentially flammable hydrogen in the exhaust stream.

Real-world examples

• 1.Hyundai NEXO fuel cell electric vehicle
• 2.Toyota Mirai fuel cell electric vehicle
• 3.Stationary fuel cell power generators
• 4.Hydrogen-powered buses