Learn about hydrogen cooling at the hydrogen refueling stations
Steven Oji discusses with Florian Lechner about the need and process of cooling hydrogen, particularly at hydrogen filling stations (HRS).
Hydrogen cooling for HRS is the process of reducing the temperature of hot gaseous hydrogen to a lower level. This process becomes crucial at hydrogen filling stations, where cooling units are installed. He detailed how a heat exchanger situated beside or inside the dispenser assists in the cooling process. When refueling, hydrogen flows from high pressure storage tanks with up to 1000 bar through a pressure regulator and a heat exchanger, which brings the temperature of the gaseous hydrogen down to -40° C. This precooling compensates for the temperature increase occurring inside the vehicle’s tank due to hydrogen compression.
In further discussion, the differentitation beween active and passive cooling method is also discussed. Active cooling is divided into direct and indirect types. In direct cooling, the hydrogen is cooled directly via a diffusion-bonded heat exchanger. With indirect cooling, an additional cooling circuit is added with a large storage tank and a liquid coolant as an intermediate. Lastly, passive cooling employs an aluminum block heat exchanger.
In the case of direct cooling for car applications, typically a cooling capacity of 45 kW of thermal energy is installed, while bus applications require up to 145 kW cooling power. He noted that direct cooling consumes much less energy in total, only during the refueling process (e.g.: 45 kW x 3 min = 2.25 kWh), while indirect cooling consumes a lot more energy in total because it needs to precool the big coolant storage continuously.
On the cost aspect, cooling of hydrogen for HRS is currently still expensive due to the many highly specialized components. However, as the technology scales up, the anticipated costs will decrease.
Looking towards the future, Florian predicted a focus on natural refrigerants, as synthetic ones have significant global warming potential. CO2 is their choice for this application because of its eco-friendliness and suitability for cooling down to -40° C. Other natural refrigerants include flammable ones like Propane or Ethane, which are posibly better suited to other applications and temperature values.
If you like the video, please also subscribe to our new Hyfindr Youtube Channel. We launched Hyfindr Tech Talks in January – a new format that is specifically designed for engineers who are interesed in the hydrogen economy!
Steven is a fuel cell system designer and he will deep-dive into the technology that makes the hydrogen economy work with real experts. We hope you will like the new format.