Method and apparatus for variable refrigerant chiller operation

摘要

A refrigeration system includes a compressor, a condenser, an expansion device, an evaporator, and an additional refrigerant vessel connected in a closed refrigerant loop. The additional refrigerant vessel is connected to the condenser at the high pressure side by a first valve and to the evaporator at a low pressure side by a second valve. A controller controls operation of the first valve and the second valve. Only one of the first valve and the second valve may be open at the same time. Refrigerant from the additional refrigerant vessel may be added to the closed refrigerant loop when the controller receives a low refrigerant level indication of in the evaporator. Refrigerant may also be removed from the closed refrigerant loop when the controller receives a high refrigerant level indication in the evaporator.

主权项

1. A refrigeration system comprising:
a compressor, a condenser, an expansion device, an evaporator, and an additional refrigerant vessel connected in a closed refrigerant loop; the additional refrigerant vessel connected to the condenser at a high pressure side by a first valve and to the evaporator at a low pressure side by a second valve; a controller to control operation of the first valve and the second valve, wherein only one of the first valve and the second valve is open at a time to allow additional refrigerant to be added to the closed refrigerant loop in response to the controller receiving a low refrigerant level indication of a refrigerant level in the evaporator, or to remove refrigerant from the closed refrigerant loop in response to the controller receiving a high refrigerant level indication of a refrigerant level in the evaporator, a chamber in fluid communication with the evaporator; and a fluid level sensor disposed within the chamber to provide a direct measurement of the refrigerant level to the controller; the controller configured to: count the number of surges occurring within a predetermined interval; increment a surge count when a surge is indicated; compare the surge count with a surge count threshold; and in response to the surge count exceeding the surge count threshold: observe a liquid refrigerant level in the evaporator with respect to a target refrigerant level; and in response to observing no change in the liquid refrigerant level over the predetermined interval, return to the step of monitoring a parameter associated with the compressor and monitor a motor current for surge indication.