Abstract: A centrifugal compressor for a chiller includes a casing, an inlet guide vane, an impeller downstream of the inlet guide vane, a motor and a diffuser. The casing has inlet and outlet portions with the inlet guide vane disposed in the inlet portion. The impeller is rotatable about a rotation axis defining an axial direction. A liquid injection passage is provided to inject liquid refrigerant into an area between the impeller and the diffuser. The motor rotates the impeller. The diffuser is disposed in the outlet portion downstream from the impeller with an outlet port of the liquid injection passage being disposed between the impeller and the diffuser. A controller is programmed to control an amount of the liquid refrigerant injected into the area between the impeller and the diffuser.

Abstract: A refrigerating apparatus includes a centrifugal compressor, suction and discharge capacity control mechanisms that control capacity of the compressor by changing opening degrees of the suction and discharge capacity control mechanisms, and a controller that compares a compressor-specific surge curve with an isentropic head to perform rotational speed control of the compressor, rotational speed adjustment control of the compressor in order to avoid surge, and emergency shutdown control of the compressor upon detection of surge. The compressor-specific surge curve is stored in the controller in advance, and is defined by an actual rotational speed of the compressor and opening degrees of the suction and discharge capacity control mechanisms. The isentropic head is calculated based on a suction pressure, a discharge pressure, and a suction temperature during operation.

Abstract: A centrifugal compressor for a chiller includes a casing, an inlet guide vane, an impeller downstream of the inlet guide vane, a motor and a diffuser. The casing has inlet and outlet portions with the inlet guide vane disposed in the inlet portion. The impeller is rotatable about a rotation axis defining an axial direction, and the impeller is adjustably mounted within the casing along the axial direction between at least a first flow rate position and a second flow rate position. The motor rotates the impeller. The diffuser is disposed in the outlet portion downstream from the impeller with a outlet port of the outlet portion being disposed between the impeller and the diffuser.

Abstract: A centrifugal compressor for a chiller includes a casing, an inlet guide vane, an impeller downstream of the inlet guide vane, a rotational magnetic bearing, a magnetic bearing sensor, a motor, a diffuser and a controller. The casing has inlet and outlet portions with the inlet guide vane disposed in the inlet portion. The impeller is attached to a shaft. The radial magnetic bearing rotatably supports the shaft. The magnetic bearing sensor detects at least one of a position signal indicative of the shaft's position and a current signal indicative of current supplied to the magnetic bearing. The motor rotates the shaft in order to rotate the impeller. The diffuser is disposed in the outlet portion downstream from the impeller. An outlet port of the outlet portion is disposed between the impeller and the diffuser. The controller is programmed to predict surge based on the position signal and/or the current signal.

Abstract: A centrifugal compressor for a chiller includes a casing, an inlet guide vane, an impeller downstream of the inlet guide vane, a motor and a diffuser. The casing has inlet and outlet portions with the inlet guide vane disposed in the inlet portion. The impeller is rotatable about a rotation axis defining an axial direction. The motor rotates the impeller. The diffuser is disposed in the outlet portion downstream from the impeller with an outlet port of the outlet portion being disposed between the impeller and the diffuser. A hot gas injection passage is provided to inject hot gas refrigerant between the inlet guide vane and the impeller. A controller is programmed to control an amount of the hot gas refrigerant.

Abstract: A refrigerating apparatus includes a centrifugal compressor, a capacity control mechanism that controls a capacity of the compressor by changing an opening degree of the capacity control mechanism, an expansion mechanism that reduces a pressure of a refrigerant, and a controller. The controller calculates an opening degree of the expansion mechanism using compressor capacity as one of a plurality of indices of change in load. The compressor capacity is obtained from a current rotation number of the compressor, an opening degree of the capacity control mechanism, and a divergence rate of a current operation head from a surge region.

Abstract: A centrifugpl compressor for a chiller includes a casing, an inlet guide vane, an impeller downstream of the inlet guide vane, a motor and a diffuser. The casing has inlet and outlet portions with the inlet guide vane disposed in the inlet portion. The impeller is rotatable about a rotation axis defining an axial direction. The motor rotates the impeller. The diffuser is disposed in the outlet portion downstream from the impeller with an outlet port of the outlet portion being disposed between the impeller and the diffuser. A hot gas injection passage is provided to inject hot gas refrigerant between the inlet guide vane and the impeller. A controller is programmed to control an amount of the hot gas refrigerant.

Abstract: A centrifugal compressor for a chiller includes a casing, an inlet guide vane, an impeller downstream of the inlet guide vane, a motor and a diffuser. The casing has inlet and outlet portions with the inlet guide vane disposed in the inlet portion. The impeller is rotatable about a rotation axis defining an axial direction. A liquid injection passage is provided to inject liquid refrigerant into an area between the impeller and the diffuser. The motor rotates the impeller. The diffuser is disposed in the outlet portion downstream from the impeller with an outlet port of the liquid injection passage being disposed between the impeller and the diffuser. A controller is programmed to control an amount of the liquid refrigerant injected into the area between the impeller and the diffuser.

Abstract: A centrifugal compressor for a chiller includes a casing, an inlet guide vane, an impeller downstream of the inlet guide vane, a motor and a diffuser. The casing has inlet and outlet portions with the inlet guide vane disposed in the inlet portion. The impeller is rotatable about a rotation axis defining an axial direction, and the impeller is adjustably mounted within the casing along the axial direction between at least a first flow rate position and a second flow rate position. The motor rotates the impeller. The diffuser is disposed in the outlet portion downstream from the impeller with a outlet port of the outlet portion being disposed between the impeller and the diffuser.

Abstract: A centrifugal compressor for a chiller includes a casing, an inlet guide vane, an impeller downstream of the inlet guide vane, a rotational magnetic bearing, a magnetic bearing sensor, a motor, a diffuser and a controller. The casing has inlet and outlet portions with the inlet guide vane disposed in the inlet portion. The impeller is attached to a shaft. The radial magnetic bearing rotatably supports the shaft. The magnetic bearing sensor detects at least one of a position signal indicative of the shaft's position and a current signal indicative of current supplied to the magnetic bearing. The motor rotates the shaft in order to rotate the impeller. The diffuser is disposed in the outlet portion downstream from the impeller. An outlet port of the outlet portion is disposed between the impeller and the diffuser. The controller is programmed to predict surge based on the position signal and/or the current signal.

Abstract: A refrigerating apparatus includes a centrifugal compressor, suction and discharge capacity control mechanisms that control capacity of the compressor by changing opening degrees of the suction and discharge capacity control mechanisms, and a controller that compares a compressor-specific surge curve with an isentropic head to perform rotational speed control of the compressor, rotational speed adjustment control of the compressor in order to avoid surge, and emergency shutdown control of the compressor upon detection of surge. The compressor-specific surge curve is stored in the controller in advance, and is defined by an actual rotational speed of the compressor and opening degrees of the suction and discharge capacity control mechanisms. The isentropic head is calculated based on a suction pressure, a discharge pressure, and a suction temperature during operation.

Abstract: A refrigerating apparatus includes a centrifugal compressor, a capacity control mechanism that controls a capacity of the compressor by changing an opening degree of the capacity control mechanism, an expansion mechanism that reduces a pressure of a refrigerant, and a controller. The controller calculates an opening degree of the expansion mechanism using compressor capacity as one of a plurality of indices of change in load. The compressor capacity is obtained from a current rotation number of the compressor, an opening degree of the capacity control mechanism, and a divergence rate of a current operation head from a surge region.

Abstract: An absorption refrigeration unit adapted to attain energy-saving by suppressing a surplus refrigerating capacity at the time of a normal operation during which the cooling water temperature is low, improve the response by ensuring adequate heating at the time of start-up operation at which the cooling water temperature is low, and avoid a pressure rise in a generator when the cooling water temperature is high or abnormality occurs. Fundamentally the amount of heat applied by a burner 31a is controlled according to the cooled water outlet temperature Tm, while the maximum permissible temperature for a high temperature generator 3 is determined according to the cooled water inlet temperature. When the temperature Tgh in the high temperature generator 3 exceeds the maximum permissible temperature determined by the cooled water inlet temperature, the amount of heat applied is reduced. During the normal operation in which the cooling water temperature is low, the amount of heat applied is reduced.