Stevens Institute of Technology
IN-1: Innovation 1

Description Low-flow liquid desiccant air-conditioning (LDAC) avoid problems such as reducing sensible cooling loads, unwanted solar gains and internal heat gains by providing dehumidification. LDAC is a new technology with the innovation design of deeply drying the air before it enters the main cooling system without the need for overcooling and reheating. Some of the main additional benefits it has are: (a) avoids the increased fan energy associated with solid desiccant systems, (b) allows more efficient ways to remove heat of sorption than is possible in solid desiccant systems, (c) eliminates the desiccant carryover problem, thereby reducing maintenance requirements compared to high-flow LDAC systems, etc. Finally LCAC systems offer improved product shelf life from improved humidity control and it has the ability to optimize temperature and humidity to increase worker comfort and productivity. Building Description Therefore, an LCAC systems was used in the Schaefer Athletic and Recreation Center at Stevens, which houses a 45 ft x 75 ft swimming pool. The major problem in pools is the maintenance of dry indoor air conditions for comfort, and the elimination of mold and mildew problems from condensation. Then, drier air increases the pool water evaporation rate, which increases the need for pool water heating. The space is conditioned and dehumidified by an air handling unit (AHU) that processes return air and OA and includes chilled water coil supplied by a central plant chiller, and preheat and reheat hot water coil supplied by a central boiler. Implementation The LDAC system was installed in Schaefer Center in August 2012. It was designed to condition 100% recirculation air, which was supplied to the air jets along the perimeter windows and it runs continuously because the continuous evaporation of pool water kept the dehumidification loads relatively constant. The LDAC is able to remove latent loads from the air and generate sensible energy that can be directed back to the pool water. This design uses the pool water to remove the heat of absorption in the LDAC conditioner, which reduces the energy to heat the pool and the energy to cool the supply air from the LDAC. Finally, the system can use waste heat or heat generated as part of a combined heat and power gas (CHP) cogeneration system to regenerate the desiccant.

Outcome The LDAC performed very well at the Schaeffer Center pool. The pool condition and water temperatures were maintained at desirable levels, and more benefits were gained from the relationship between the pool operation and LDAC operation. The system provided all the pool heating (with no auxiliary heating required), space condition were as desired,and the vapor compression AHU was doing minimal dehumidification. while the outdoor conditions were hot and humid. Finally, in August 2012 the facility manager reported the LDAC system was performing better than expected and reports from pool occupants were outstanding.