A novel technology for cooling and dehumidification is nearing commercialization through several strategic partnerships, including GE Vernova, BASF and Carrier Global. Montana Technologies’ (Ronan, Mont.; www.mt.energy) AirJoule technology employs a metal-organic-framework (MOF) desiccant material that exhibits higher water-uptake capacity and faster atmospheric water extraction when compared to traditional desiccant systems, and with significantly reduced energy consumption. “When desiccant dehumidifier systems remove water from air, a significant heat of adsorption is naturally generated that up to now has been transferred to the air stream and warms it up. In addition, most desiccant systems require adding even more external heat to regenerate the desiccant media, which is often added to the system’s cooling load. With AirJoule, we use a pressure-swing approach and do not introduce any external heat. In addition, we capture that heat of adsorption and use it for regeneration. We basically have a net-zero thermal energy balance when extracting water from an airstream,” explains Pete McGrail, chief technology officer of Montana Technologies. The AirJoule system is configured as two chambers working in tandem. As humid air is drawn into one chamber, the MOF media adsorbs water vapor. Simultaneously, the heat of adsorption is transferred to the other chamber to begin regenerating the media. “Air is flowing through one chamber all the time, while the other chamber is being regenerated under a modest vacuum,” says McGrail. The system cycles between chambers every 5–10 min.
However, there are limitations on the system’s ability to compress water vapor while maintaining its energy balance. “We’re compressing the water vapor just enough to condense it. We have designed specialized equipment to handle low-pressure water vapor and minimize the energy requirement,” adds McGrail. Once the water is a liquid, it takes a trivial amount of energy to bring it up to atmospheric pressure for discharge and use.
Many applications for AirJoule are in HVAC and water-heating installations, but the company has also seen interest in applying the technology as a replacement for evaporative cooling systems in aluminum-smelting and data-center applications.