HVAC&R | Submarines
HVAC systems for submarines differ significantly from HVAC systems for surface ships. The HVAC system also differs between the type of submarine; conventional diesel-powered submarines versus nuclear-powered submarines. In both types of submarines oxygen is not handled by the HVAC system. Oxygen is handled by air purifiers or CO2 absorbers (on diesel-powered submarines) or oxygen generators (on nuclear-powered systems).
Electro Magnetic Compatibility
A vital factor in choosing the right HVAC system is selecting compact, EMI/EMC suitable and low-magnetic components. This is particularly important during stealth mode. Electric motors generate internal magnetic stray fields which can be detected. To avoid that it is necessary to reduce these signatures as much as possible by implementing degaussing techniques.
HVAC systems for submarines have to withstand BV043 or MIL-S-901D shock values and high seawater pressure levels. The condensers and pumps are directly subject to changing seawater pressures up to 40 bars under 400 meter depth. This requires very special (tailor-made) equipment and system design. Moreover, all the ships have to withstand severe shock levels in which generally a one-layer mounting is not sufficient, which can be solved by using multi-layer mounting.
All these requirements have to be solved in the most compact, maintenance-friendly design, because the most scarce thing on a submarine is space.
Another scarce thing on submarines, generally for diesel-powered ones, is power. The ships are powered by batteries (hundreds of them), and having an efficient system means less necessity to resurface. This is one of the most crucial specifications for submarines and largely influences the design of the HVAC system.
Finally; among all above parameters, probably the most important ones are airborne and structural borne noise. During stealth mode most of the systems are paused, but weaponry systems and the chiller still work in order to provide cooling to those systems. Therefore; the first and utmost goal of HVAC systems for submarines is to be quiet.