[ heat transfer ]
Table 1 : Technology comparison ( fixed process temperature )
Air Fin Cooler ( AFC ) AFC with spray system AFC with adiabatic pads Cooling tower
Installation |
12 bays , 2 bundles per bay , tube length 15 m |
6 bays , 2 bundles per bay , tube length 15 m |
6 bays , 2 bundles per bay tube length 15 m |
4 cells 8.7 m x 8.7 m |
Min . achievable process temp . |
39 ° C |
39 ° C |
39 ° C |
29 ° C |
Number of fans |
36 |
18 |
18 |
4 |
Total plot space 80 x 15 m ( 1200 m 2 ) 40 x 15 m ( 600 m 2 ) 40 x 15 m ( 600 m 2 ) 8.7 m x 37.8 m ( 329 m 2 ) Installed motor power 1,330 kW 666 kW 900 kW 300 kW
Annual electrical consumption |
100 % |
50 % |
70 % |
25 % |
Annual Evaporated water amount |
N / A |
6,395 m 3
|
6,395 m 3
|
385,440 m 3
|
Annual Water usage * |
N / A |
6,395 m 3
|
8,527 m 3
|
514,212 m 3
|
CAPEX factor |
100 % |
65 % |
85 % |
25 % |
* Based on a cycle of concentration ( CoC ) of 4 , which depends on make-up water quality |
Electrolyser capacity : 100 MW |
Design capacity of the central cooling system : 32 MW |
Dry / Wet-bulb temperature : 30 ° C / 21 ° C |
Switch-on temperature of the spray system : 23 ° C |
Table 2 : Technology comparison ( aiming at lowest process temperature )
Air Fin Cooler ( AFC ) AFC with spray system AFC with adiabatic pads Cooling tower
Installation |
12 bays , 2 bundles per bay , tube length 15 m |
6 bays , 2 bundles per bay , tube length 15 m |
6 bays , 2 bundles per bay tube length 15 m |
4 cells 8.7 m x 8.7 m |
Min . achievable process temp . |
39 ° C |
31.5 ° C |
31.5 ° C |
29 ° C |
Number of fans |
36 |
36 |
36 |
4 |
Total plot space |
80 x 15 m ( 1200 m 2 ) |
80 x 15 m ( 1200 m 2 ) |
80 x 15 m ( 1200 m 2 ) |
8.7 m x 37.8 m ( 329 m 2 ) |
Installed motor power |
1,330 kW |
1,330 kW |
1,725 kW |
300 kW |
Annual electrical consumption |
100 % |
102 % |
130 % |
25 % |
Annual Evaporated water amount |
N / A |
10,924 m 3
|
10,924 m 3
|
385,440 m 3
|
Annual Water usage * N / A 10,924 m 3 14,565 m 3 514,212 m 3 CAPEX factor 100 % 115 % 140 % 25 %
* Based on a cycle of concentration ( CoC ) of 4 , which depends on make-up water quality Electrolyser capacity : 100 MW Design capacity of the central cooling system : 32 MW Dry / Wet-bulb temperature : 30 ° C / 21 ° C Switch-on temperature of the spray system : 23 ° C
While water and air flow through the tube bundle , the water evaporates , causing the water film on the tubes to cool down . Below the bundle , the water drops in the water basin , from where it is pumped back to the top to be sprayed over the tube bundle . The air turns to the second part of the tower and flows upwards , through the fan . The air velocities in the turning section and in the second part of the tower are designed in such a way that any droplets will drop back into the water basin .
Because air and water flow downwards together ( co-current flow ), the air helps to spread water evenly over the entire tube surface . There will be no dry spots , resulting in less scaling and fouling .
The Tundracel is therefore suitable for poor water qualities , such as :
• Blowdown from cooling towers and boilers
• Waste streams from demineralizers , scrubbers , etc .
• Plant effluent wastewater
• Brackish water
Conclusion
At the two extremes , for thermal management in green hydrogen plants there is the choice for dry cooling or wet cooling . In general , it can be
18 Hydrogen Tech World | Issue 6 | October 2022