Patent ID: 7849916

Claim:
An apparatus for use with a process liquid for controlling the temperature of a target, comprising a tank adapted for holding the process liquid and having an inlet for receiving the process liquid from the target and an outlet for returning the process liquid to the target, a pump for drawing the process liquid out of the tank and having an input and an output, a heat exchanger having a process liquid input and a process liquid output, a first liquid passageway for fluidly coupling the output of the pump to the process liquid input of the heat exchanger, a second liquid passageway for fluidly coupling the process liquid output of the heat exchanger to the inlet of the tank and including a middle section that bifurcates into first and second branches, first and second digital valves disposed respectively in the first and second branches of the second liquid passageway, and a controller coupled to the first and second digital valves and configured to determine a period of time to open the first digital valve when a temperature value is in a lower temperature range and to open the second digital valve when the temperature value is in a higher temperature range so as in each case to allow a portion of the process liquid from the output of the pump to be diverted toward the tank through the heat exchanger, the temperature value being selected from the group consisting of a temperature reading of the target, a temperature reading of the process liquid, a desired temperature for the target, and a desired temperature for the process liquid.