Cookie Dough Cooling

Requirement:

Supply 40 degree water for human consumption on a year round basis for mixing with cookie dough on a batch basis. Groups of four mixers on each of four floors with mixer requiring 12 gpm of new water for 3 minutes per batch.

The total water drawdown requirement approximates 22 gallons per minute. The source of make-up water is from the city mains at a maximum temperature of 85 degrees F.

An existing winterized cooling tower is available for condensing purposes.

Solution:

Use a dual compressor 60 HP chiller with a two circuit stainless steel barrel to cool 22 gpm of make up water to 40 degrees and delivered with any unused water returned from the process to a 600 gallon storage tank for delivery through the mixer loop nominally 75 gpm, 48 gpm of which will be used by the mixers.

A secondary pair of pumps will continuously recirculate nominally 20 gpm in a loop between the tank and the chiller barrel.

Each of the compressors contains unloaders such that unloading will occur when the chiller barrel load decreases. The use of hot gas bypass on the last stage of unloading prevents short cycling.

The quantity of make up water required is electrically controlled by the tank water level. All materials in contact with the process water are of stainless steel, copper or brass with no galvanized or carbon steel present.

 

5/3/99

Kenneth W. Wicks

ASHRAE Fellow