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Cryogenic H2-cooling system for refueling vehicles.

Number: 117

Author(s) : HERZOG F., GOCKEL F., ALTINDAL S.

Summary

When vehicles are refueled with hydrogen, the gas flows from a high-pressure storage tank through a dispenser into the vehicle tank and heats up because of a negative Joule-Thomson coefficient. In addition, compression of the hydrogen in the tank results in further temperature increase. To fill the vehicle tank completely without exceeding permissible pressures and temperatures, the hydrogen must be cooled during the overflow process.
Corresponding H2 coolers with the associated refrigeration compressors are available, but they are expensive, maintenance-intensive and not particularly reliable. In addition, their design is difficult because the refueling processes are highly fluctuating and demand short-term peak loads from the cooling system.
To avoid the problems with mechanical chillers Messer has developed an alternative cooling system which runs on liquid nitrogen.
The apparatus consists of a vessel with an internal coil for conducting the hydrogen. This spiral is surrounded by cooling tubes that are flooded with liquid nitrogen. The apparatus is filled with a water/glycol mixture so that all hydrogen and nitrogen tubes are immersed in this buffer medium.
In operation, the apparatus is first cooled with liquid nitrogen till a complete phase change of the water/glycol mixture (from liquid to slurry) is achieved. The phase change temperature can be set between -10°C and -55°C by selecting the appropriate mixing ratio. In the frozen state, the H2-cooler is held in waiting position.
When a vehicle is connected to the H2-dispenser, refueling can start and hydrogen passes through the coil where its temperature decreases. During this process, the water/glycol mixture melts at (almost) constant temperature. As a result, the hydrogen temperature at the cooler outlet is also almost constant, even if the refueling process is interrupted or switched on and off in short terms. This is important to enable efficient refueling.

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Pages: 6 p.

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Details

  • Original title: Cryogenic H2-cooling system for refueling vehicles.
  • Record ID : 30031049
  • Languages: English
  • Source: Proceedings of the 17th IIR International Conference on Cryogenics, Dresden, Germany, april 25-28 2023
  • Publication date: 2023/04/25
  • DOI: http://dx.doi.org/10.18462/iir.cryo.2023.0117

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