By accurately regulating hydrogen recirculation, fuel utilization can be maximized, water accumulation can be reduced, and the system’s lifespan can be extended.

Ravenstein, May 30, 2025 — Precise control of anode recirculation is essential for the efficiency and longevity of PEM fuel cells. By accurately regulating hydrogen recirculation, fuel utilization can be maximized, water accumulation can be reduced, and the system's lifespan can be extended.

Robust Against Contaminants in the Gas Stream
Conventional calorimetric and thermal measurement methods reach their limits in PEM fuel cells: High humidity and condensation lead to persistent damage. Additionally, these methods cannot detect gas composition and, therefore, cannot automatically adjust to fluctuations during the purge cycle.

In contrast, Allengra's ultrasonic measurement principle is highly robust and resistant to contamination and impurities in the gas stream.

Comprehensive Data for Optimal Hydrogen Management
Allengra's hydrogen flow meter is the only sensor on the market that simultaneously measures mass and volumetric flow while analyzing gas composition in real time. This significantly improves the performance of PEM fuel cells and other hydrogen-based applications..

By integrating advanced sensor technologies, including temperature, pressure, and humidity sensors, the device provides comprehensive data for optimal anode management.

Reliable Measurement Under Extreme Conditions
The sensor is designed for operation at temperatures up to 85 °C and pressures up to 16 bar. Even at 100% relative humidity, it remains reliably functional and can even tolerate liquid water droplets to some extent.

The robust housing, made of highly resistant stainless steel 316L, ensures long-term compatibility with the humid hydrogen-nitrogen mixture and guarantees optimal integration into the fuel cell stack. At high hydrogen concentrations, it measures gas composition with an accuracy of < 0.5%, while volumetric flow measurement achieves an accuracy of 3% of the measured value.

All relevant parameters—volumetric and mass flow, temperature, pressure, humidity, and the concentrations of hydrogen (H₂), nitrogen (N₂), and water vapor (H₂O)—are transmitted along with additional diagnostic data via the integrated CAN bus and Modbus interfaces.

With just one device, all relevant measurements can be collected and easily integrated into fuel cell system controls.

Adaptable for different areas of application
The hydrogen flow meter is available in two versions to meet different requirements:
● DN15 for flow rates from 10-1000 L/min
● DN20 for 20-1700 L/min

Both models are only 173 mm long and feature standard threaded connections for easy integration.

Maximum Efficiency and Longevity for PEM Fuel Cells
The advanced features of the hydrogen flow meter make it an essential component of PEM fuel cells. By precisely measuring hydrogen flow and gas composition, it optimizes anode recirculation control, ensures an ideal hydrogen-nitrogen ratio, and maximizes efficiency.

Additionally, the sensor provides valuable data on nitrogen and water crossover, preventing excessive nitrogen and water accumulation in the stack. This ensures that the system remains in optimal balance between efficiency and longevity.

Innovation and Sustainability in Focus
Allengra implements technological innovation in ultrasonic measurement principles for sustainable hydrogen propulsion systems—actively contributing to the energy transition. The hydrogen flow meter enables more efficient hydrogen utilization, supporting the shift to green energy solutions.
Versatile applications in:
● Automotive - particularly heavy-duty trucks, but also passenger cars
● Stationary applications - such as backup power supplies and decentralized energy networks
● Aviation - hydrogen-powered propulsion systems

For series applications, Allengra offers customized adaptations of the hydrogen sensor. This allows for cost-efficient production and optimal integration into the compact installation spaces of OEM fuel cell systems, including mechanical and electronic interfaces.

Meet Allengra at hy-fcell Canada 2025 - Booth #109
Allengra's hydrogen flow meter for anode recirculation will be presented for the first time in North America at hy-fcell Canada 2025, held June 4-5 at the Vancouver Convention Centre East. Visit Booth #109 in the German Pavilion to explore live demos and talk to our experts.

About Allengra Allengra GmbH specializes in the development and production of ultrasonic flow sensors and control valves suitable for both high-end products and cost-efficient mass-production solutions. Since its founding in 2005, the company, headquartered in Germany and Romania, has provided customized solutions for various industries, including heat pumps, coffee machines, industrial automation, and motorsports. With extensive engineering
expertise and prototyping capabilities, innovative ideas are quickly transformed into market-ready products.