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Hydrogen
Photo courtesy of Kelvion.
A temperature approach of minimum approx. 5 K in relation to the dry bulb temperature should be present for a dry cooling system to make sense. In cases where the ambient air conditions are high and pure dry cooling cannot be realized, the air coolers can be equipped with an adiabatic system in the form of a spray, pad or hybrid system. Depending on the size of the plant and the amount of waste heat there are two directions to consider – dry, adiabatic or hybrid cooling based on V-type standard coolers up to a thermal duty of approx. 50 MW. If the thermal duty exceeds 50 MW it can make sense to use Air Cooled Heat Exchangers( ACHE) as the cooling system, being by nature more customized, using bigger fans, a steel structure beneath and, if needed, fulfilling higher requirements like API 661. If enough water for cooling purposes is available, a purely wet cooling system by means of a cooling tower is the right choice. In general, a pure dry cooling system has the biggest footprint and highest electrical consumption whilst a pure wet system has the smallest footprint, but the highest water consumption. Regarding heat exchange solutions in an electrolyzer system, the ambient air-based cooling system has, in most cases, the highest CAPEX share in relation to the required heat exchanger equipment for the electrolyzer plant. Furthermore, temperature levels in PEM and AWE are moderate in the range of 60- 80 ° C. Depending on the ambient conditions, the temperature difference to the ambient air temperature can be very small. It is therefore hugely important to follow an holistic approach when designing the thermal management of the plant. This means optimizing the different heat exchangers and temperature levels to each other to achieve the most efficient setup. When investigating and designing the central recooling system, all factors that are relevant for its
design must be taken into account to come up with the best system setup. The factors to consider for the central cooling system are manifold and include:
• Ambient conditions like dry bulb temperature and wet bulb temperature
• Planned CAPEX budget
• Water availability on site
• Allowed sound power / sound pressure level
• Temperature levels and thermal duties of the sub-systems
• Electrical consumption and OPEX
• Plant location like altitude, pollution, atmosphere
• Available plot size
So, for example, for one project the available footprint can be the dominant driver while for another project the allowed water consumption is dominant.
Photo courtesy of Kelvion. www. heat-exchanger-world. com Heat Exchanger World July 2025
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