“The most energy efficient, zero condensate, low GHG impact dehumidification sub-system for air conditioning”.
In HVAC, Ionic Liquid Desiccant (ILD) sub-systems are being developed to provide latent cooling for high humidity environments, decoupled from sensible cooling. Currently, both sensible and latent cooling are provided by conventional vapor compression (DX) systems utilizing HCFC coolants.
A closed-loop membrane contactor charged with an ionic liquid acts like a cooling coil, dehumidifying the incoming fresh air by absorbing water vapor into the desiccant solution. Like a conventional condensing unit, a second closed-loop membrane contactor utilizes warm outdoor air supplemented by waste heat (from separately provided sensible cooling or other available sources) to remove the absorbed moisture to the outside environment. ILD systems do not produce condensate water, eliminating the requirement to manage this discharge.
Xergy is developing this technology in conjunction with heat pumps that employ novel electrochemical compressors and metal hydride heat exchangers to produce high efficiency air conditioning units.
In HVAC latent cooling (dehumidification) applications, water vapor is selectively removed from the humid supply air, permeating through the walls of the XION™ pervaporative tubes into an ionic liquid dessicant (ILD) circulated in a closed-loop membrane contactor. A second membrane contactor and waste heat are employed to remove the added moisture from the liquid desiccant and reject it to the outside as water vapor. No liquid condensate water is produced.
Schematic courtesy of the National Renewable Energy Laboratory.
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