Adaptive hot gas bypass control for centrifugal chillers
AssigneeYork International Corporation
InventorsGregory K. Beaverson, Harold B. Ginder, Dennis L. Deltz
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Abstract
An adaptive control apparatus and a method for automatically controlling a refrigeration system as a function of cooling load and head. A control panel controls the operation of a hot gas bypass valve so as to avoid surging of the compressor in response to cooling load and head. The control apparatus and method also allow for automatic self calibration.
Claims32
A method for automatically calibrating a surge control of a refrigeration system including a centrifugal compressor, a condenser, pre-rotational vanes, a load, and an evaporator through which a chilled liquid refrigerant is circulated, said method comprising:
- sensing a presence of a surge condition;
- sensing a head parameter representative of the head of the compressor;
- sensing a load parameter representative of the load;
- and
- storing the head parameter and the load parameter when the surge condition is sensed as calibration data to be used by the control of the refrigeration system;
- sensing a present head parameter representative of the present head of the compressor;
- sensing a present load parameter representative of the present load;
- and
- controlling the operation of a hot gas bypass valve so as to avoid surging in the compressor in response to the present head parameter, the present load parameter, and the stored control calibration data.
The method of 4, wherein storing the head parameter includes
- storing the pressure ratio, minus a small margin, as a stored control pressure ratio when the surge condition is sensed;
- and
- storing the corresponding vane position as a stored control vane position when the surge condition is sensed.
A method for controlling a hot gas bypass valve in a refrigeration system including a centrifugal compressor, a condenser, pre-rotational vanes, and an evaporator through which a chilled liquid refrigerant is circulated, said method comprising:
- sensing a present pressure representative of the present pressure of the liquid refrigerant in the condenser;
- sensing a present pressure representative of the present pressure of the liquid refrigerant in the evaporator;
- sensing a present vane position representative of the present position of the pre-rotational vanes;
- and
- controlling the operation of the hot gas bypass valve so as to avoid surging in the compressor in response to the present condenser pressure, the present evaporator pressure, and the present vane position to stored calibration data.
An apparatus for automatically calibrating a surge control of a refrigeration system including a centrifugal compressor, a condenser, pre-rotational vanes, a load, and an evaporator through which a chilled liquid refrigerant is circulated, said method comprising:
- means for sensing a presence of a surge condition;
- means for sensing a head parameter representative of the head of the compressor;
- means for sensing a load parameter representative of the load;
- means for storing the head parameter and the load parameter when the surge condition is sensed as calibration data to be used by the control of the refrigeration system;
- means for sensing a present head parameter representative of the present head of the compressor;
- means for sensing a present load parameter representative of the present load;
- and
- means for controlling the operation of a hot gas bypass valve so as to avoid surging in the compressor in response to the present head parameter, the present load parameter, and the stored control calibration data.
The apparatus of 18, wherein means for storing the head parameter includes
- means for storing the pressure ratio, minus a small margin, as a stored control pressure ratio when the surge condition is sensed;
- and
- means for storing the corresponding vane position as a stored control vane position when the surge condition is sensed.
An apparatus for controlling a hot gas bypass valve in a refrigeration system including a centrifugal compressor, a condenser, pre-rotational vanes, and an evaporator through which a chilled liquid refrigerant is circulated, said apparatus comprising:
- means for sensing a present pressure representative of the present pressure of the liquid refrigerant in the condenser;
- means for sensing a present pressure representative of the present pressure of the liquid refrigerant in the evaporator;
- means for sensing a present vane position representative of the present position of the pre-rotational vanes;
- and
- means for controlling the operation of a hot gas bypass valve so as to avoid surging in the compressor in response to the present condenser pressure, the present evaporator pressure, and the present vane position to stored calibration data.
A refrigeration system including a centrifugal compressor, a condenser, pre-rotational vanes, a hot gas bypass valve, and an evaporator through which a chilled liquid refrigerant is circulated, said apparatus comprising:
- means for sensing a present pressure representative of the present pressure of the liquid refrigerant in the condenser;
- means for sensing a present pressure representative of the present pressure of the liquid refrigerant in the evaporator;
- means for sensing a present position representative of the present position of the pre-rotational vanes;
- and
- means for controlling the operation of the hot gas bypass valve so as to avoid surging in the compressor in response to a comparison of the present condenser pressure, the present evaporator pressure, and the present vane position, or functions thereof, to stored calibration data.
Dependencies are inferred from the claim text.