[ heat exchange ]
A sample from an ASHRAE database showing the distribution of temperature conditions at a specific location over the course of a year , essential for optimising cooling strategies in different climates .
is typically employed , with 30 – 45 % of the electrolysing capacity managed by this system over its lifecycle ( meaning 30 – 45 MWth to be dissipated ).
Design considerations for large-scale green hydrogen plants
There are multiple solutions to cool the process fluid :
• Wet cooling towers : These are costeffective , requiring less energy and space compared with other options . They can achieve a temperature approach of less than 5 ° C with a plate-and-frame heat exchanger for a closed-loop system . However , they result in a water loss of around 2 %, which can be significant in regions with water scarcity and may affect local acceptance .
• Air fin coolers : When water is unavailable or highly restricted , air-cooled heat exchangers such as air fin coolers are used . Kelvion has developed specific finned tubes called Groovy-Fin ® tubes , which enhance the heat exchange coefficient and allow a smaller temperature approach using the same surface area compared to AFCs equipped with standard tubes . However , despite their high performance , there are limitations in cooling the process fluid during hot weather or in harsh , arid environments when the Logarithmic Mean Temperature Difference ( LMTD ) is below 5 ° C .
Cascade Cooling reduces energy consumption and water waste
To optimise hydrogen production and minimise the levelised cost of hydrogen , a cooling system
Table 1
Equipment installed
Plot area required ( m x m ) without pump skids
Adiabatic fogging system
24 bays AFC + 8 pump skids ( 6 pumps each )
110 m x 18.3 m ( AFC )
Cascade Cooling
24 bays AFC + 6 cooling towers + skids ( 1 pump and 1 PHE )
110 m x 18.3 m ( AFC ) + 6 x 10 m x 9 m ( WCT )
Annual water consumption ( m ³) 120,000 m ³ 90,000 m ³ −25 % Annual electrical consumption ( MWh ) 4,450 3,650 −18 %
Hydrogen Tech World | Issue 18 | October 2024 17