Oil-free liquid chiller

A centrifugal liquid chiller comprising:

• a condenser, said condenser condensing refrigerant gas to the liquid state when said chiller is in operation;
• a metering device, said metering device receiving refrigerant from said condenser and reducing the pressure thereof;
• an evaporator, said evaporator receiving refrigerant from said metering device and causing liquid refrigerant to evaporate when said chiller is in operation;
• a compressor, said compressor being driven by a motor, said compressor receiving refrigerant from said evaporator and delivering refrigerant in the gaseous state to said condenser when said chiller is in operation, said compressor having a shaft, at least one impeller being mounted on said shaft, said shaft being rotatably supported by at least one bearing, said at least one bearing being a rolling element bearing, the rolling elements of said bearing being fabricated from a ceramic material, said at least one bearing being lubricated by refrigerant and in the absence of oil, refrigerant delivered to said at least one bearing for lubrication purposes being at least primarily in the liquid state and a portion of the refrigerant used in the lubrication of said at least one bearing being permitted to vaporize at the location of said at least one bearing as a result of the bearing lubrication process;
• a source location for liquid refrigerant, discrete from said evaporator and condenser, from which liquid refrigerant is supplied to said at least one bearing for bearing lubrication purposes;
• and
• means for delivering liquid refrigerant [is delivered] from said condenser to said source location for bearing lubrication purposes and to said motor for motor cooling purposes while said chiller is in operation, and from a location other than said condenser when said chiller starts up and until such time as liquid refrigerant comes to be available for such purposes from said condenser.

A centrifugal liquid chiller comprising:

• a condenser, said condenser condensing refrigerant gas to the liquid state when said chiller is in operation;
• a metering device, said metering device receiving refrigerant from said condenser and reducing the pressure thereof;
• an evaporator, said evaporator receiving refrigerant from said metering device and causing liquid refrigerant to evaporate when said chiller is in operation;
• a compressor, said compressor being driven by a motor, said compressor receiving refrigerant from said evaporator and delivering refrigerant in the gaseous state to said condenser when said chiller is in operation, said compressor having a shaft, at least one impeller being mounted on said shaft, said shaft being rotatably supported by at least one bearing, said at least one bearing being a rolling element bearing, the rolling elements of said bearing being fabricated from a ceramic material, said at least one bearing being lubricated by refrigerant and in the absence of oil, refrigerant delivered to said at least one bearing for lubrication purposes being at least primarily in the liquid state and a portion of the refrigerant used in the lubrication of said at least one bearing being permitted to vaporize at the location of said at least one bearing as a result of the bearing lubrication process;
• a source location for liquid refrigerant, discrete from said evaporator and condenser, from which liquid refrigerant is supplied to said at least one bearing for bearing lubrication purposes;
• and
• means for delivering liquid refrigerant to both said source location for bearing lubrication purposes and to said motor for motor cooling purposes while said chiller is in operation, refrigerant used for bearing lubrication and motor cooling purposes being returned to said condenser after such uses.

A centrifugal liquid chiller comprising:

• a condenser, said condenser condensing refrigerant gas to the liquid state when said chiller is in operation;
• a metering device, said metering device receiving refrigerant from said condenser and reducing the pressure thereof;
• an evaporator, said evaporator receiving refrigerant from said metering device and causing liquid refrigerant to evaporate when said chiller is in operation;
• a compressor, said compressor receiving refrigerant from said evaporator and delivering refrigerant in the gaseous state to said condenser when said chiller is in operation, said compressor having a shaft, at least one impeller being mounted on said shaft, said shaft being rotatably supported by at least one bearing, said at least one bearing being a rolling element bearing, the rolling elements of said bearing being fabricated from a ceramic material, said at least one bearing being lubricated by refrigerant and in the absence of oil, refrigerant delivered to said at least one bearing for lubrication purposes being at least primarily in the liquid state and a portion of the refrigerant used in the lubrication of said at least one bearing being permitted to vaporize at the location of said at least one bearing as a result of the bearing lubrication process;
• and
• a reservoir, said reservoir being continuously replenished with liquid refrigerant when said chiller is operating and replenishment being discontinued when said chiller shuts down, said reservoir containing sufficient liquid refrigerant, when said chiller shuts down, to provide for the lubrication of said at least one bearing as said shaft coasts to a stop.

A centrifugal liquid chiller comprising;

• a condenser, said condenser condensing refrigerant gas to the liquid state when said chiller is in operation;
• a metering device, said metering device receiving refrigerant from said condenser and reducing the pressure thereof;
• an evaporator, said evaporator receiving refrigerant from said metering device and causing liquid refrigerant to evaporate when said chiller is in operation;
• a compressor, said compressor receiving refrigerant from said evaporator and delivering refrigerant in the gaseous state to said condenser when said chiller is in operation, said compressor having a shaft, at least one impeller being mounted on said shaft, said shaft being rotatably supported by at least one bearing, said at least one bearing being a rolling element bearing, the rolling elements of said bearing being fabricated from a ceramic material, said at least one bearing being lubricated by refrigerant and in the absence of oil, refrigerant delivered to said at least one bearing for lubrication purposes being at least primarily in the liquid state and a portion of the refrigerant used in the lubrication of said at least one bearing being permitted to vaporize at the location of said at least one bearing as a result of the bearing lubrication process;
• a source location for liquid refrigerant, discrete from said evaporator and condenser, from which liquid refrigerant is supplied to said at least one bearing;
• a motor for driving said compressor;
• a drive for said motor;
• and
• a pump, said pump pumping liquid refrigerant from one of said condenser and said evaporator to said source location for bearing lubrication purposes and to said motor and to said drive, for purposes of cooling said motor and said drive, while said chiller is in operation.

A centrifugal chiller comprising:

• a condenser, said condenser condensing refrigerant gas to the liquid state when said chiller is in operation;
• a metering device, said metering device receiving refrigerant from said condenser and reducing the pressure thereof;
• an evaporator, said evaporator receiving refrigerant from said metering device and causing liquid refrigerant to evaporate when said chiller is in operation;
• a compressor, said compressor receiving refrigerant from said evaporator and delivering refrigerant in the gaseous state to said condenser when said chiller is in operation, said compressor having a shaft and a motor, at least one impeller and the rotor of said motor being mounted on said shaft, said shaft being rotatably supported by at least one bearing of other than the magnetic, hydrostatic or hydrodynamic type, said at least one bearing having rolling elements, the rolling elements of said bearings being fabricated from a ceramic material and having a lower density, a higher modulus of elasticity and being less sensitive to thermal expansion than rolling elements fabricated from steel, the rolling elements of said bearing being lubricated exclusively by refrigerant;
• a reservoir, said reservoir being the location from which refrigerant is supplied to said at least one bearing for lubrication thereof and being isolated from said condenser when said chiller shuts down, isolation of said reservoir at chiller shutdown causing sufficient pressure to be retained in said reservoir to drive liquid refrigerant from said reservoir to said at least one bearing as said shaft coasts to a stop;
• and
• a pump, said pump pumping liquid refrigerant from said condenser to said reservoir subsequent to start-up of said chiller.

A method of operating a centrifugal refrigeration chiller having a condenser and an evaporator comprising the steps of:

• mounting an impeller on a shaft;
• mounting said shaft for rotation in a bearing, said bearing being a rolling element bearing, the rolling elements of said bearing being fabricated from a ceramic material;
• providing a source location for liquid refrigerant which is discrete from said condenser and said evaporator, said source location containing liquid refrigerant for purposes of lubricating said bearing both when said chiller is operating and for a period of time subsequent to shutdown of said chiller during which said shaft coasts to a stop in said bearing;
• delivering liquid refrigerant, in the absence of oil, from said source location to said bearing both while said chiller is in operation and as said shaft coasts to a stop subsequent to chiller shutdown;
• and
• permitting a portion of the liquid refrigerant delivered to said bearing for bearing lubrication purposes in said delivering step to vaporize at the location of said bearing as a result of the lubrication thereof by said refrigerant.

A method for lubricating a rolling element bearing in and for cooling the drive motor of a centrifugal refrigeration chiller having a condenser and an evaporator where the rolling elements of the bearing are fabricated from a ceramic material comprising the steps of:

• mounting at least one impeller and the rotor of the drive motor on a shaft;
• supporting the shaft for rotation in the rolling element bearing;
• delivering liquid refrigerant, in the absence of oil, to the rolling element bearing for purposes of lubricating the bearing;
• permitting a portion of the liquid refrigerant delivered to said bearing in said delivering step to vaporize at the location of said bearing;
• and
• delivering liquid refrigerant to the drive motor for purposes of cooling the motor when the chiller is in operation.

A liquid chiller comprising:

• a condenser, said condenser condensing liquid refrigerant to the liquid state when said chiller is in operation;
• a metering device, said metering device receiving refrigerant from said condenser;
• an evaporator, said evaporator receiving refrigerant from said metering device;
• a compressor, said compressor receiving refrigerant gas from said evaporator and delivering refrigerant gas to said condenser when said chiller is in operation, said compressor having a shaft, said shaft being rotatably supported by at least one bearing;
• and
• pump apparatus, said pump apparatus being connected to draw refrigerant from both said condenser and said evaporator and pumping liquid refrigerant from at least one of said condenser and said evaporator for the purpose of lubricating said at least one compressor bearing.

An oil-free bearing lubrication and motor cooling system in a centrifugal chiller comprising:

• a condenser, said condenser condensing refrigerant gas to the liquid state when said chiller is in operation;
• a metering device, said metering device receiving refrigerant from said condenser and reducing the pressure thereof;
• an evaporator, said evaporator receiving refrigerant from said metering device and causing liquid refrigerant to vaporize when said chiller is in operation;
• a motor housing;
• a motor, said motor being cooled by refrigerant;
• a compressor, said compressor having a shaft, at least one impeller and the rotor of said motor being mounted on said shaft, said shaft being rotatably supported by at least one bearing, said at least one bearing being a rolling element bearing, at least one component of said rolling element bearing being fabricated from a ceramic material, said bearing being lubricated by refrigerant in the absence of oil;
• a reservoir for liquid refrigerant;
• means for delivering liquid refrigerant both to said at least one bearing for lubrication thereof in the absence of oil and to said motor for motor cooling purposes, said at least one bearing being lubricated by liquid refrigerant which is first delivered to said reservoir and is then directed to said at least one bearing;
• and
• means for metering liquid refrigerant to said motor at a first flow rate during the start-up of said chiller and at a second and higher flow rate when the shaft of said chiller has achieved operational speeds and the load on said chiller exceeds a predetermined load.

A liquid chiller comprising:

• a compressor;
• a motor for driving said compressor;
• a condenser, said condenser receiving compressed refrigerant gas from said compressor;
• a metering device, said metering device receiving refrigerant from said condenser;
• an evaporator, said evaporator receiving refrigerant from said metering device;
• and
• a pump, said pump being connected to draw refrigerant from both said condenser and said evaporator and to deliver liquid refrigerant from at least one of said condenser and said evaporator to said motor for purposes of cooling said motor.

A method of lubricating a bearing in a refrigeration chiller comprising the steps of:

• connecting pump apparatus to pump liquid refrigerant from both the condenser and the evaporator of said chiller;
• controlling the output of said pump apparatus so that the liquid refrigerant pumped thereby is from the one of said condenser and said evaporator where liquid refrigerant is available and is at higher pressure;
• and
• delivering at least a portion of liquid refrigerant output of said pump apparatus to said bearing so as to lubricate said bearing.

A method of cooling a motor in a refrigeration chiller comprising the steps of:

• connecting pump apparatus to pump liquid refrigerant from both the condenser and the evaporator of said chiller;
• controlling the output of said pump apparatus so that the liquid refrigerant pumped thereby is from the one of said condenser and said evaporator where liquid refrigerant is available and is at higher pressure;
• and
• delivering at least a portion of liquid refrigerant output of said pump apparatus to said motor so as to cool said motor.