[ gas cooling ]
hydrogen gas . Vaporised CO 2 gas returns to the
CO 2 liquefier equipment , and the cycle is repeated . In hydrogen refuelling systems where thermal energy storage is required , a larger aluminium block heat exchanger can be used to store cold energy from the vaporising CO 2
.
Hydrogen refuelling nozzle
Compressed hydrogen gas storage in a bus
At present , cooling hydrogen to -40 ° C is the common practice . However , it is likely that cooling to only -20 ° C will become more popular to avoid the need for low-temperature systems and decrease the energy consumption . The Society of Automotive Engineers ( SAE ) has published T40 and T20 Protocols in the J2601 series to allow for different pre-cooling temperatures at -40 ° C and -20 ° C .
The SAE is also considering additional refuelling protocols for cooling to -10 ° C and ambient temperature gas transfer . These will reduce the complexity of the cooling system .
Liquid hydrogen
When cryogenic liquid hydrogen is stored at the HRS , the thermal management may take a different approach . Liquid hydrogen is stored at around -253 ° C . If it is decanted directly into the vehicle to be stored as liquid onboard in a cryogenic tank , there is no need to vaporise or warm the liquid hydrogen .
If liquid hydrogen is used for storage at the HRS , but the vehicle tank is to receive highpressure compressed gaseous hydrogen , the configuration becomes more complex . The liquid is pumped to the required pressure of around 450 bar for trucks and buses , or 850 bar for cars . These pressures allow a driving force into the storage tanks , which will operate at 350 bar and 700 bar , respectively .
The high-pressure liquid is then vaporised in a heat exchanger and enters a high-pressure gas storage bank . The warm energy for vaporisation may either come from ambient air or a water bath . The vaporisation can be controlled to ensure that the hydrogen is warmed to -40 ° C . As the gas leaves the high-pressure storage bank , it can be chilled against liquid hydrogen . In this case , no additional chiller is required .
About the author
Stephen B . Harrison is the founder and managing director of sbh4 GmbH in Germany . He focuses on decarbonisation technologies and strategies . Hydrogen and Power-to-X are fundamental pillars of his consulting practice . With a background that includes 27 years at BOC Gases , BOC Group , and Linde Gas , Stephen possesses an intimate knowledge of hydrogen from commercial , technical , operational , and safety perspectives . His expertise extends across the full length of the value chain , from production , purification , distribution , and storage through to utilisation .
50 Hydrogen Tech World | Issue 16 | June 2024