Energy Conservation in Process Chilled Water Systems

The energy consumption of the chiller and cooling tower in a process cooling application was analyzed using the TRNSYS computer code. The basic system included a constant speed centrifugal chiller and an induced-draft, counterflow cooling tower. Typical performance data was used to generate empirical models of the chiller and cooling tower. The cooling load profile was based on averaged electrical demand data for three plastic processing plants. The simulation was conducted using hourly Typical Meteorological Year weather data to determine the cooling tower operating conditions. Three alternative systems were modeled to predict the savings associated with the following energy conservation options: 1) variable speed drive chiller, 2) two-speed cooling tower fan, and 3) natural cycle cooling. The annual energy savings are presented as a function of cooling tower outlet temperature and average cooling load ratio