American Standard Inc.

American Standard International Inc.

Paul F Haley

Dennis R Dorman

Paul C Rentmeester

Merle A Renaud

Brian S Junk

Rick T James

A method of optimizing the design of a chiller involves placing more emphasis on the chiller's performance at part load than at full load and rating the chiller accordingly. In some embodiments, compressor speed and impeller diameter are chosen to optimize the chiller's performance at part load. With the chosen impeller diameter, operation at full load is then achieved by increasing compressor speed, opening inlet guide vanes, and perhaps sacrificing some efficiency. If necessary, an inverter over speeds the compressor by driving it at a speed beyond that which the compressor would normally run if it were driven at the nominal line frequency of the electrical power feeding the inverter.

Method of optimizing and rating a variable speed chiller for operation at part load

This controller is used for controlling a centrifugal compressor along its path of minimum power consumption while avoiding a surge condition. It is especially useful in a refrigeration system having a variable speed centrifugal compressor with adjustable inlet guide vanes. In such an application, the controller opens the inlet guide vanes enough to satisfy the cooling demand and then, to minimize power consumption, reduces the speed of the compressor while further opening the vanes (compensating for the reduced speed) until either the inlet guide vanes are fully open or an impending surge condition is detected. The onset of a surge condition is detected by monitoring motor current fluctuations. When fluctuations above a predetermined amplitude occur in excess of a predetermined frequency, the controller determines that a surge is impending. The controller continues to control the compressor in this manner, providing a capacity that is minimally above a level that would cause a surge yet is sufficient to satisfy the cooling demand.

Centrifugal compressor controller for minimizing power consumption while

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La Crosse, WI, United States of America

Paul F Haley