Liquid Desiccant System for Combined Humidity and Chloride Control

ABSTRACT: As stated in the solicitation, the Air Force spends $4.5 billion annually on aircraft maintenance related to corrosion. A significant fraction of this expenditure could be saved by a Corrosion Mitigation System (CMS) that both limited a shelter's indoor relative humidity to less than 50% while capturing airborne chloride particles. However, these functions, particularly humidity control, can be expensive to implement with conventional dehumidifiers. Liquid desiccant dehumidifiers are uniquely suited to efficiently control indoor humidity. Since a liquid desiccant can dehumidify air without over-cooling the air, the high latent loads of an active aircraft shelter in a humid locale can be met without excessive (and wasteful) sensible cooling. Furthermore, a liquid-desiccant CMS has the potential to capture airborne chloride particles as it absorbs moisture. Recent advances can significantly reduce the energy use and improve the O & M characteristics of a liquid-desiccant CMS. The proposed work will study (1) liquid desiccant conditioners that use membranes to prevent droplet carryover, (2) two-stage regenerators that can almost halve the thermal energy required by the CMS, and (3) non- corrosive alternatives to the traditional lithium chloride. The major deliverable for the proposed work is a recommended configuration for a liquid-desiccant CMS that could be field tested in a second phase of work. BENEFIT: If successful, the Corrosion Mitigation System (CMS) developed in the proposed work will provide the Air Force an effective means to significantly reduce maintenance costs for aircraft. The liquid desiccant technology that is the focus of this work can also be used for humidity control in standard HVAC applications. This close sharing of technology will lead to advances crossing over in both directions between the CMS and HVAC fields.