Oil-free liquid chiller
First Claim
1. A 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 compressive element 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 non-metallic material, said at least one bearing being lubricated by refrigerant and in the absence of oil; and
a source location for liquid refrigerant, discrete from said evaporator and condenser, from which liquid refrigerant is supplied to said at least one bearing.
1 Assignment
0 Petitions
Accused Products
Abstract
A refrigeration chiller employs a centrifugal compressor the impellers of which are mounted on a shaft which is itself mounted for rotation using rolling element bearings lubricated only by the refrigerant which constitutes the working fluid of the chiller system. Apparatus is taught for providing liquid refrigerant to (1.) the bearings immediately upon chiller start-up, during chiller operation and during a coastdown period subsequent to shutdown of the chiller and (2.) the drive motor of the chiller'"'"'s compressor for motor cooling purposes. By use of a variable speed-driven motor to drive the compressor, optimized part load chiller performance is achieved in a chiller which does not require or employ an oil-based lubrication system.
33 Citations
133 Claims
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1. A liquid chiller comprising:
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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 compressive element 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 non-metallic material, said at least one bearing being lubricated by refrigerant and in the absence of oil; and
a source location for liquid refrigerant, discrete from said evaporator and condenser, from which liquid refrigerant is supplied to said at least one bearing. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45)
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46. A centrifugal chiller comprising:
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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 bearing having rolling elements and being lubricated exclusively by refrigerant, the rolling elements of said bearing having a lower density, a higher modulus of elasticity and being less sensitive to thermal expansion than rolling elements fabricated from steel;
a reservoir, said reservoir being the location from which refrigerant is supplied to said at least one bearing for the lubrication thereof; and
means for replenishing the liquid refrigerant in said reservoir when said chiller is in operation. - View Dependent Claims (47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58)
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59. An oil-free bearing lubrication and motor cooling system in a centrifugal chiller comprising:
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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;
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 and said motor being cooled by refrigerant; and
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. - View Dependent Claims (60, 61, 62, 63, 64, 65, 66, 67, 68, 69)
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70. A method of operating a centrifugal refrigeration chiller having a condenser and an evaporator comprising the steps of:
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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; and
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. - View Dependent Claims (71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87)
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88. 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:
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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; and
delivering liquid refrigerant to the drive motor for purposes of cooling the motor when the chiller is in operation. - View Dependent Claims (89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102)
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103. A liquid chiller comprising:
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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. - View Dependent Claims (104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115)
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116. A liquid chiller comprising:
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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. - View Dependent Claims (117, 118, 119, 120)
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121. A method of lubricating a bearing in a refrigeration chiller comprising the steps of:
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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. - View Dependent Claims (122, 123, 124, 125, 126, 127, 128)
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129. A method of cooling a motor in a refrigeration chiller comprising the steps of:
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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. - View Dependent Claims (130, 131, 132, 133)
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Specification