Indoor pools, water parks and natatoriums can benefit from the efficient dehumidification provided by LDACs. In preparation for a demonstration that began 2012, AILR studied the potential energy savings for installing an LDAC at the Schaefer Athletic and Recreation Center at the Stevens Institute of Technology (Hoboken, NJ). The Stevens facility houses a 45’ x 75’ pool. The continuous evaporation from the pool creates a demand for dehumidification within the building as well as for direct heating of the pool to keep it at 80 F. Dehumidification and temperature control within the building had been provided by a 11,000 cfm, six-row, chilled water coil (45 F entering chilled water) that at design conditions provided 22.0 tons sensible cooling and 14.5 tons latent cooling. A water-to-water heat exchanger provided up to 681 MBH heating to the pool. Condensation on the cooler windows of the building had been controlled by heating 3,240 cfm of air to raise the air temperature to 120 F (140 MBH) and delivering this air to a perimeter air curtain that blankets the windows.
The liquid-desiccant air conditioner (LDAC) for the pool at the Schaefer Center eliminates essentially all of the 140 MBH that was used to heat the perimeter air and a significant fraction of the 681 MBH that was used to heat the pool. At the same time, the LDAC provides 11 tons of latent cooling to the space, which directly reduces the load on the chilled water coil that had been doing both sensible and latent cooling. The LDAC deeply dries the 3,240 cfm supplied to the perimeter air curtain. The supply dewpoint for this air is below 45 F, effectively avoiding condensation on the windows without heating the air. Pool water directly cools the LDAC, so the latent load served by the LDAC, which approximately equals the evaporative heat loss from the pool, is returned to the pool. The 200 MBH that is needed to regenerate the liquid desiccant is met by recovering heat from a 75 kW CHP system that is installed at the site.
Assuming that the equivalent of 2,000 hours per year of full load perimeter air heating had been occurring at Schaeffer, the LDAC saves 280 million Btu for this function. In addition, assuming that the LDAC operates at an equivalent of 2,500 full-load hours per year, it saves 380 million Btu for pool heating while reducing the load on the building’s chilled water loop by 27,500 ton-hours.