Design and Testing of a Separate Sensible and Latent Cooling Packaged Terminal Air Conditioning Unit

Packaged terminal air conditioning (PTAC) systems are typically utilized for space heating and cooling in hotels and apartment buildings. However, they cool the air to low temperature for dehumidification and some reheating may be required to resolve overcooling. A prototype of a solid desiccant wheel assisted separate sensible and latent cooling (SSLC) PTAC system was designed and constructed, which has a cooling capacity of 3.5 kW. The heat exchangers and vapor compression cycle were modeled in in-house software, CoilDesigner and VapCyc. The modeling results show improvement in the coefficient of performance from 3.12 to 4.05 or 30%. Cost study was conducted to evaluate the economics of SSLC PTAC units within the U.S. climate conditions. The study shows the payback period for the national average could be as low as 2 years. The system was experimentally tested and its performance was not as expected due to some design challenges. This paper highlights the lessons learned from the modeling and experimental work and discusses the economic analysis in addition to future design improvements and system optimization.