US 6,718,779 B1 · Method to optimize chiller plant operation

Abstract

A chiller plant which produces chilled water for airconditioning, or an industrial process and which is comprised of chillers, cooling fluid pumps, and cooling towers with electrical motor drives uses a substantial amount of energy. A method that coordinates the operation of the cooling tower, cooling fluid pumps, and refrigeration machines so that the chiller plant operates at a higher overall efficiency thus reducing the power usage has been developed and is presented herein. The flow rate of the cooling fluid pumps are controlled to maintain a precise temperature difference across the refrigerant condenser. The cooling tower fans are controlled by comparing the cooling fluid temperature and the cooling fluid flow rate to selected design parameters. The heat rejection rate is measured for each chiller in the chiller plant and operating set points are established for each operating chiller to provide the optimum operation for best energy efficiency.

Claims17

Dependent claims

A method to optimize a chiller plant, that reduces overall energy use, comprising:

(a) a first means for measuring temperature difference of a cooling fluid entering and leaving a condenser of a chiller,
(b) a second means for providing a predetermined temperature difference set point, thereby providing a constant temperature difference demand between said cooling fluid entering and leaving said condenser of said chiller during any operating condition of said chiller,
(c) a third means for controlling flow rate of said cooling fluid to maintain the cooling fluid temperature at said predetermined set point, whereby the reduction of pumping energy is larger then the increase in energy use of said chiller and a cooling tower of said chiller plant so that the total energy use of said chiller plant is reduced without changing the refrigeration output of said chiller.

A method to optimize a chiller plant, that reduces overall energy use, comprising:

(a) a first means for measuring a flow rate of cooling fluid entering a condenser of a chiller of said chiller plant,
(b) a second means for providing a maximum fan speed set point of a fan or fans of a cooling tower of said chiller plant,
(c) a third means for adjusting said maximum fan speed set point as a function of said flow rate, whereby the reduction in the energy use of the fan is greater then the increase in energy use of said chiller so that the total energy use of said chiller plant is reduced without changing the refrigeration output of said chiller.

A Chiller Plant Optimizer comprising:

(a) a computerized controller for calculating a temperature difference between the entering and leaving temperatures of a cooling fluid that flows through a condenser of a chiller of a chiller plant and,
(b) said computerized controller for comparing the actual temperature difference of said cooling fluid to a predetermined temperature difference of said cooling fluid and,
(c) said computerized controller for calculating a control output signal as a function of the calculated difference between said actual temperature difference and said predetermined temperature difference, thereby controlling a flow rate of said cooling fluid to maintain the cooling fluid temperature difference at or near said predetermined temperature difference, whereby the reduction of energy use by a cooling fluid pump of said chiller plant is greater then the increase in energy use of said chiller and a cooling tower of said chiller plant so that the total energy use of said chiller plant is reduced without changing the refrigeration output of said chiller.

Dependencies are inferred from the claim text.

Method to optimize chiller plant operation

Life of this patent

Method to optimize chiller plant operation

Life of this patent

Abstract

Claims17