Technology Description

The LDDX technology is a small-tonnage, packaged air conditioner that has more than twice the dehumidification capacity (latent cooling) of a conventional air conditioner. High latent cooling is achieved by integrating a liquid desiccant with the evaporator and condenser of a vapor-compression refrigeration circuit. This integration is effectively accomplished by replacing the traditional aluminum-finned/copper-tube heat exchangers found in a conventional direct-expansion (DX) air conditioner with a unique wicking-fin heat exchanger that allows thin films of the liquid desiccant to cover the surfaces of the heat exchanger. On the cooled evaporator surfaces of the LDDX, the cool desiccant absorbs more water than would be condensed in a conventional evaporator. On the heated condenser surfaces, the water that was absorbed in the evaporator is released by the warm desiccant and carried by the condenser's cooling air flow. Since air does not have to be cooled below its dewpoint to condense the water vapor, the LDDX's evaporator can run at a higher temperature than that of a conventional DX air conditioner. This relatively high evaporator temperature leads to an efficient, high latent cooling system.

This project will install a 3-ton and a 5-ton LDDX on buildings at Picatinny Arsenal, New Jersey, and Fort Belvoir, Virginia. In addition to demonstrating the LDDX's ability to control indoor humidity without overcooling or reheating (i.e., the traditional approach to humidity control in humid climates), the demonstration will identify the operations and maintenance (O&M) procedures required to keep the LDDX operating effectively.