Chiller Design Model - Impact of chiller failure on the short-term temperature variation in the incubation of salmonids

In salmon recovery programs it is commonly necessary to chill incubation and early rearing temperatures to match wild development times. The most common failure mode for a chiller system is failure of the chiller or circulating pumps. Following chiller failure, the water temperature can rise from 5-7 C to 10-13 C depending on the well temperatures and ambient air temperatures.

The speed and magnitude of the temperature increases depends on how the chillers are designed. The simplest design is a direct-coupled chiller with chilled gas/process water heat exchanger. Other chiller designs include both chilled glycol and water reservoirs. The addition of these reservoirs serves to reduce the maximum rate of temperature change following chiller failure. Increased deformities have been observed in direct-coupled chiller systems for sockeye salmon following chiller failures.
This model can be used to size glycol and water reservoirs to control the rise in temperature following chiller failure.