US3648479A - Refrigeration system with multiple centrifugal compressors and load balancing control - Google Patents

Refrigeration system with multiple centrifugal compressors and load balancing control Download PDF

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US3648479A
US3648479A US75914A US3648479DA US3648479A US 3648479 A US3648479 A US 3648479A US 75914 A US75914 A US 75914A US 3648479D A US3648479D A US 3648479DA US 3648479 A US3648479 A US 3648479A
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electric motor
compressor
capacity
electric
compressors
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US75914A
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Douglas K Richardson
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Daikin Applied Americas Inc
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Westinghouse Electric Corp
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Assigned to CITICORP INDUSTRIAL CREDIT INC. reassignment CITICORP INDUSTRIAL CREDIT INC. SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: SNYDERGENERAL CORPORATION
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Assigned to SNYDERGENERAL CORPORATION, A CORP. OF MINNESOTA, MCQUAY INC., A CORP. OF MINNESOTA reassignment SNYDERGENERAL CORPORATION, A CORP. OF MINNESOTA RELEASED BY SECURED PARTY (SEE DOCUMENT FOR DETAILS). Assignors: CITICORP NORTH AMERICA, INC.
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B49/00—Arrangement or mounting of control or safety devices
    • F25B49/02—Arrangement or mounting of control or safety devices for compression type machines, plants or systems
    • F25B49/022—Compressor control arrangements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D27/00—Control, e.g. regulation, of pumps, pumping installations or pumping systems specially adapted for elastic fluids
    • F04D27/02—Surge control
    • F04D27/0269—Surge control by changing flow path between different stages or between a plurality of compressors; load distribution between compressors
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D23/00—Control of temperature
    • G05D23/19—Control of temperature characterised by the use of electric means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
    • F25B2400/07—Details of compressors or related parts
    • F25B2400/075—Details of compressors or related parts with parallel compressors

Definitions

  • a refrigeration capacity control for a system having a single centrifugal compressor is shown in my copending patent application Ser. No. 28,678, filed Apr. 15, 1970. This invention relates to the specific electrical interconnection of two or more such capacity controls when two or more centrifugal gas compressors are to be used in a single refrigeration load circuit.
  • centrifugal gas compressor when used to compress a refrigerant gas are therefor required to have movable capacity controls and one such control determines the positions of movable suction inlet pre-rotation vanes for the compressor to vary the compressor capacity.
  • An electrical control circuit for automatically positioning such inlet vanes to provide a predetermined control of refrigeration of air conditioning system parameters such as for example the chilled outlet water temperature is disclosed in my copending patent application as previously referred to.
  • a current sensing coil is also provided to operate an overload relay whenever the current drawn by the electric motor driving the compressors exceeds a predetermined amount corresponding to an overload condition.
  • the operation of the overload relay causes the inlet vanes of the associated compressor to move in a decrease capacity direction until the sensed overload current is reduced to a safe value at which the operated overload relay restores to the nonoperated condition upon which the movement of the inlet vanes towards a decreased capacity position is stopped.
  • each gas compressor should have its own capacity control circuit responding to the common system condition such as chilled water temperature or the like.
  • Such a control should be simple, reliable and also inexpensive.
  • a refrigeration system is provided with at least two centrifugal gas compressors supplying compressed refrigerant gas to a single common refrigerant load circuit and each compressor is provided with an inlet capacity control and an electrical control circuit therefor.
  • Each control circuit includes a solenoid valve which, when energized, causes the capacity control to move in the decrease capacity direction.
  • the power supply to each compressor motor includes circuit means having a current responsive device such as a current sensing coil and a respective relay connected to the respective coil to be operated when the current drawn by the associated compressor motor is more than a predetermined amount.
  • An electrical circuit interconnection between the sensing coils for each compressor motor is such that the respective relay for the motor drawing the most current will be operated to decrease the compressor capacity until the current drawn by that motor is reduced to an amount balancing the respective current drawn by the other compressor motor.
  • Such electrical interconnection according to the invention is very simply effected by a particular interconnection of conductors and or resistors between the current sensing coils so that the current sensed by one coil will flow through a resistor in opposition to the current sensed by another coil and so forth.
  • This invention also provides respective circuit means including resistors and contactors responsive to energization of each compressor motor to short circuit the associated current sensing coil and relay when that respective compressor and motor are not energized and operating.
  • circuit means including resistors and contactors responsive to energization of each compressor motor to short circuit the associated current sensing coil and relay when that respective compressor and motor are not energized and operating.
  • FIG. I is a diagrammatic view of the refrigeration system having two compressors and a load balancing circuit of the invention
  • FIG. 2 is a diagrammatic and fragmentary sectional view of the mechanism for adjustment of a capacity control vanes of one of the centrifugal gas compressors: such as shown in FIG. 1 of the drawings;
  • FIG. 3 is an enlarged sectional view of the two interconnected solenoid adjusted valves of FIG. 2, the piston of the valves being shown in the positions they take when the solenoid coils of the two valves are deenergized;
  • FIG. 4 is a view similar to FIG. 3 except that one solenoid coil, the left one, is energized;
  • FIG. 5 is a view similar to FIG. 4 except that the other solenoid coil, the right one is energized;
  • FIG. 6 is a circuit diagram of the load sharing capacity control system of the invention as may be used with three electric motor driven compressors.
  • a centrifugal gas compressor 1 driven by an electric motor 2 and a second centrifugal gas compressor 3 driven by the electric motor 4 are connected in parallel in a refrigeration circuit including compressed gas conduits 5 and 6 to the condenser 7.
  • the condenser 7 is connected through an expansion valve 8 to the evaporator chiller 9 having a chilled water outlet at 10.
  • the evaporated refrigerant gas from the chiller 9 is connected through the suction pipes 11 and 12 in parallel to the inlets of the respective centrifugal gas compressors 1 and 3.
  • Each of the centrifugal gas compressors 1 and .3 is provided with inlet vanes which are movable to vary the capacity of the compressor, and-these inlet vanes are of the well known pre-rotation type which will be shown and described in some detail in connection with FIG. 2 of the drawings. It should be understood that this invention would apply to any refrigeration system having two or more compressors connected to a common refrigeration load whether or not the load includes a common refrigerant gas circuit. In other words a plurality of refrigerant gas circuits may be connected to chill a common water load or the like.
  • the electric motor 12 is supplied with operating current by means of the conductors l5 and 16 while similarly the electric motor 4 is supplied with operating current by means of conductors l7 and 18.
  • the gas compressor 1 is provided with a capacity control mechanism including a chilled water temperature sensing device 19 connected to the condition sensor 20 to actuate switches 21 or 22 according to sensed chilled water temperature.
  • the centrifugal gas compressor 3 is provided with a capacity control including the chilled water temperatures.
  • the centrifugal gas compressor 3 is provided with a capacity control including the chilled water temperature sensing element 23 connected to the condition sensor 24 to actuate switches 25 or 26 to maintain a desired chilled water temperature.
  • the details of the condition sensors 20 and 24 will not be described herein as they are not necessary to an understanding of the present invention but if more information is desired reference may be made to the aforementioned copending patent application Ser. No. 28678, filed Apr. 15, 1970 It should be mentioned, however, that if the chilled water temperature is lower than desired, the condition sensors 20 and 24 will respond to close contacts 21 and 25 respectively to energize the decrease capacity solenoid valve coils 27 and 28 respectively.
  • condition sensors 20, 24 respectively will respond to close switch contacts 22, 26 respectively and energize the increase capacity solenoid valve coils 29 and 30.
  • the solenoid valve coils 27 or 28 When either of the solenoid valve coils 27 or 28 is energized the inlet vanes for the associated centrifugal gas compressor 1 or 3 will be moving in the decrease capacity direction.
  • the increased capacity solenoids 29 or 30 When either of the increased capacity solenoids 29 or 30 is energized, the associated inlet vanes for the gas compressor 1, 3 will be moving in the increased capacity direction.
  • FIGS. 2-5 of the drawings A fluid pressure system for actuating or operating a centrifugal capacity control as is to be provided for each of the gas compressors 1 or 3 will not be described although if a more detailed understanding of such a system is desired, reference may be made to the aforementioned US. Pat. No. 3,350,897.
  • the inlet cone 40 of the associated centrifugal compressor is provided with a plurality of movable pre-rotation spin vanes such as shown at 41 and it should be understood that the rotatable position of the spin vane 41 as it may be rotated about its axis 42 will vary the capacity of the centrifugal compressor in a manner well known to those skilled in the art.
  • a piston 43 is slidable within a cylinder having cylinder portions 44 and 45. When fluid under pressure is supplied to cylinder portion 44 and drained from cylinder portion 45, the piston 43 will move to the right in a manner to rotate the capacity control means or vane 41 toward the position opening the intake and increasing the capacity of the compressor.
  • valves VA and VB are double acting valves as shown more in detail by FIGS. 35 of the drawings for supplying fluid under pressure selectively to either or both of the cylinder areas 44 and 45 and for selectively draining fluid under pressure from either cylinder areas 44 or 45.
  • both solenoid valves VA and VB are shown in their deenergized position with their solenoids coils 29 and 27 not connected to a source of electric energizing potential.
  • the valves VA and VB are in the deenergized position as shown by FIG. 3 of the drawings, fluid under pressure in the line 52 is passed through needle valves 53 and 54 through conduits and 51 to both respective cylinder portions 44 and 45 thus balancing the capacity control piston 43 at a predetermined position.
  • the associated valve VA will be operated to allow the pressure of the cylinder area 44 to drain through conduit 50 into the drain conduit thus allowing the fluid under pressure in the cylinder area 45 to overbalance the fluid pressure in the cylinder area 44 and move the pistons 43 to the left in a decrease capacity direction in a manner to change the capacity control to a lower capacity or closed position.
  • valve VB will be operated to allow the fluid under pressure in the cylinder area 45 to drain to the conduit 51 to the fluid pressure return conduit 60, thus allowing the pressure in the cylinder area 44 to overcome the pressure in the cylinder area 45 and move the pistons to the right in an increase capacity direction to change the capacity control to increase the capacity and open the intake valve.
  • a current sensing coil is positioned in inductive relation to the conductor 15 supplying current to the electric motor 2 for the gas compressor 1.
  • a current sensing coil 71 is provided in an inductive relation to the conductor 18 supplying the operating current to the electric motor 4 for this second gas compressor 3.
  • An overload relay 72 is connected across the terminals of the current sensing coil 70 and similarly an overload relay 73 is connected across the terminals of the current sensing coil 71. If the current drawn by either electric motor 2 or 4 should exceed a predetermined,
  • the potential induced in the respective sensing coil 70 or 71 will cause the respective voltage sensitive overload relay 72 or 73 to operate.
  • the overload relay 72 is operated by an overloaded condition for the electric motor 2 and gas com pressor l, the contact 72' will be closed to energize the down capacity solenoid valve coil 27 thus moving the inlet vanes for the gas compressor 1 in a decrease capacity direction.
  • the current drawn by the associated electric motor 2 will be reduced such as to cause the overload relay 72 to be restored to a non-operated condition, thus deenergizing the decrease capacity solenoid coil 27.
  • the overload relay 73 is energized, its contact 73' will be closed to operate the decrease capacity solenoid coil 28.
  • the current sensing coil 70 is interconnected with the current sensing coil 71 through resistors 75, 76 and 77. These interconnections and coils are of a polarity to result in opposing currents flowing through the resistor 76, one current flowing in one direction being the current induced in sensing coil 70 and the other current flowing in the opposite direction being the current induced in the sensing coil 71.
  • the associated overload relay 72 or 73 can be caused to be operated when the current drawn by one of the electric motors 2 or 4 appreciably differs from the current drawn by the other electric motor 2 or 4.
  • the connections are such that should the electric motor 2, for example, draw more current than the electric motor 4, indicating that the gas compressor 1 is working at higher capacity than the gas compressor 3, the overload relay 72 would be energized to close its contacts 72' and actuate the decrease capacity solenoid coil 27 to adjust the inlet vanes for the gas compressor 1 in a direction to reduce its capacity until its capacity approximates that of the capacity of the gas compressor 3 as may be indicated by a current flow through the conductor approximately the same as the current flow through conductor 18.
  • Another feature of the invention is the provision of shorting contactors 80 and 81 respectively for the associated current sensing contactor coils 70 and 71.
  • the shorting contactor 80 is normally open but is operated to be closed when current is not supplied to operate the electric motor 2 and energize the shorting contactor coil 82.
  • the shorting contactor 81 is normally opened but will be closed and operated when current is not passing through the shorting contactor coil 83 to the electric motor 4.
  • the resistors 75 and 77 will enable the capacity control and the overload responsive circuit for the operating one of the electric motors 2 or 4 to continue to function even though another one of them may be deenergized with its current sensing overload detecting coil shorted.
  • Sensing coil 90 is inductively related to the current leads for the electric motor of a first gas compressor not shown.
  • sensing coil 91 is associated with the current leads to the electric motor for a second centrifugal gas compressor while the current sensing coil 92 is associated with the current leads to a third electric motor driving a third centrifugal gas compressor not shown.
  • Resistors 93, 94, 95, 96, 97 and 98 are connected in the arrangement shown to provide the desired bridge circuit interconnections so that opposing currents flow through the resistors 94, 96 and 98 associated with a respective sensing coil 90, 91 and 92.
  • the sensing coils 90, 91 and 92 are poled as shown respectively to produce the desired opposing currents flowing in the sensing resistors 94, 96 and 98 as previously described.
  • Each overload relay controlling the associated decrease capacity solenoid valve is connected to the terminals of the respective sensing coils 90-93 as shown at 100, 101, 102, 103 and 104, 105 respectively.
  • a shorting contactor 110 is associated with the current sensing coil 90 and a similar shorting contactor 111 is associated with sensing coil 91 and shorting contactor 112 is associated with sensing coil 92.
  • Each of the shorting contactors 110-112 are operated by associated shorting contactor coils similar to the contactor coils 82 or 83 previously described in connection with FIG. 1 of the drawings.
  • any one of the electrically driven compressors associated with the respective current sensing coils 9092 to be deenergized and not operating while the remainder of the compressors that are connected in parallel in the common refrigerant system remain operated and the arrangement is such that the load sharing would be evenly divided between the total number of operating compressors regardless of how many of the other compressors are not energized for any reason whatsoever.
  • the chain circuit of FIG. 6 may be expanded indefinitely to include as many parallel connected electric motor driven centrifugal compressors as would be desired for a given refrigeration system.
  • the load sharing circuit of the invention has been described in connection with a particular type of capacity control designed to operate with inlet pre-rotation capacity controlling vanes for centrifugal compressors, it should be obvious that the load sharing circuit could be used with other forms of capacity controls and centrifugal compressor systems. Various mo ifications will occur to those skilled in the art.
  • a refrigeration system comprising, a refrigerant load, at least two electric motor driven centrifugal gas compressors cor mected in parallel to said load and each having movable capacity control means, respective electric control means to be energized to move the capacity control means of each compressor in the decrease capacity direction, respective electric circuit means responsive to current drawn by the respective electric motor of each compressor to energize the respective electric control means for reducing the capacity of the as sociated compressor, and means electrically interconnecting the respective electric circuit means of each compressor to decrease the capacity of a particular compressor as its electric motor current tends to increase above the current drawn by the other electric motors for the other compressors connected to the refrigerant load thus balancing the loads on all compressors.
  • each of said respective electric circuit means is overload responsive to energize the respective control means when the electric current drawn by the associated compressor motor exceeds a predetermined amount.
  • the means electrically interconnecting the respective electric circuit means is comprised of at least one resistor in which are passed in opposition respective electric currents corresponding to the respective currents drawn by one electric motor associated with one compressor and another electric motor associated with another compressor.
  • said respective electric circuit means includes a current sensing coil associated with a power conductor for the respective electric motor and there is provided means for short circuiting the respective coil when the associated electric motor is not energized 5.
  • said respective electric circuit means includes a current sensing coil associated with a power conductor for the respective electric motor and there is provided means for short circuiting the respective coil when the associated electric motor is not energized.
  • said respective electric circuit means includes a current sensing coil associated with a power conductor for the respective electric motor and there is provided means for short circuiting the respective coil when the associated electric motor is not energized.
  • said respective electric circuit means includes a current sensing coil associated with a power conductor for the respective electric motor and there is provided means for short circuiting the respective coil when the associated electric motor is not energized.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Automation & Control Theory (AREA)
  • Control Of Positive-Displacement Air Blowers (AREA)
  • Control Of Positive-Displacement Pumps (AREA)
  • Control Of Non-Positive-Displacement Pumps (AREA)
US75914A 1970-09-28 1970-09-28 Refrigeration system with multiple centrifugal compressors and load balancing control Expired - Lifetime US3648479A (en)

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US (1) US3648479A (enrdf_load_stackoverflow)
AU (1) AU465521B2 (enrdf_load_stackoverflow)
CA (1) CA923212A (enrdf_load_stackoverflow)
DE (1) DE2147394C2 (enrdf_load_stackoverflow)
ES (1) ES395343A1 (enrdf_load_stackoverflow)
FR (1) FR2108039B1 (enrdf_load_stackoverflow)
GB (1) GB1328628A (enrdf_load_stackoverflow)
IT (1) IT938839B (enrdf_load_stackoverflow)

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4205537A (en) * 1978-12-11 1980-06-03 General Electric Company Multiple hermetic-motor compressor in common shell
US4494006A (en) * 1982-09-15 1985-01-15 Compressor Controls Corporation Method and apparatus for controlling a multicompressor station
US4494382A (en) * 1983-10-11 1985-01-22 Carrier Corporation Method and apparatus for controlling when to initiate an increase in compressor capacity
US4519748A (en) * 1982-09-10 1985-05-28 Frick Company Micro-processor control of compression ratio at full load in a helical screw rotary compressor responsive to compressor drive motor current
US4614090A (en) * 1985-01-31 1986-09-30 Yanmar Diesel Engine Co. Ltd. Outdoor unit of an air conditioner of an engine heat pump type
US5195329A (en) * 1991-11-12 1993-03-23 Carrier Corporation Automatic chiller plant balancing
US5894739A (en) * 1997-07-10 1999-04-20 York International Corporation Compound refrigeration system for water chilling and thermal storage
US6602057B2 (en) 2001-10-01 2003-08-05 Dresser-Rand Company Management and optimization of load sharing between multiple compressor trains for controlling a main process gas variable
WO2004013494A1 (en) * 2002-08-06 2004-02-12 York International Corporation Stability control system and method for centrifugal compressors operating in parallel
CN103759482A (zh) * 2007-10-31 2014-04-30 江森自控科技公司 控制气体压缩系统容量的方法以及气体压缩系统
EP3156747A4 (en) * 2014-06-10 2018-01-17 Toshiba Carrier Corporation Heat source machine and heat source device
US20220290906A1 (en) * 2019-09-30 2022-09-15 YORK (WUXI) AIR CONDITIONING AND REFRIGERATION Co.,Ltd. Load Balancing Method for Two Compressors

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JPS58193055A (ja) * 1982-05-04 1983-11-10 株式会社東芝 ヒ−トポンプ形エアコン
US4560319A (en) * 1983-08-01 1985-12-24 MAN Maschinenfabrik Unternehmensbereich GHH Sterkrade Method and apparatus for controlling at least two parallel-connected turbocompressors
DE3937152A1 (de) * 1989-11-08 1991-05-16 Gutehoffnungshuette Man Verfahren zum optimierten betreiben zweier oder mehrerer kompressoren im parallel- oder reihenbetrieb
JPH055545A (ja) * 1991-04-26 1993-01-14 Toshiba Corp 空調システムの電流制御装置
KR100437054B1 (ko) * 2002-05-27 2004-06-23 엘지전자 주식회사 히트펌프의 과부하 방지장치 및 그 방법

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US2178100A (en) * 1937-05-13 1939-10-31 Curtis Refrigerating Machine C Refrigerating condensing unit
US2336671A (en) * 1933-11-29 1943-12-14 Gen Motors Corp Refrigerating apparatus
US3362185A (en) * 1966-06-20 1968-01-09 Westinghouse Electric Corp Refrigeration systems with centrifugal compressors and air cooled condensers

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DE972394C (de) * 1954-01-09 1959-07-16 Siemens Ag Einrichtung zur Drehmomentregelung von Doppelantrieben, insbesondere fuer Doppelantriebe von Walzgeruesten
DE1117710B (de) * 1954-05-24 1961-11-23 Siemens Ag Lastausgleichsregelung von Mehrmotorenantrieben mit Nebenschlussmotoren
US3350897A (en) * 1966-01-11 1967-11-07 Westinghouse Electric Corp Controls for centrifugal compressors having spin vanes in their inlets
US3609989A (en) * 1970-04-15 1971-10-05 Westinghouse Electric Corp Control for refrigeration system centrifugal compressor

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2336671A (en) * 1933-11-29 1943-12-14 Gen Motors Corp Refrigerating apparatus
US2178100A (en) * 1937-05-13 1939-10-31 Curtis Refrigerating Machine C Refrigerating condensing unit
US3362185A (en) * 1966-06-20 1968-01-09 Westinghouse Electric Corp Refrigeration systems with centrifugal compressors and air cooled condensers

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4205537A (en) * 1978-12-11 1980-06-03 General Electric Company Multiple hermetic-motor compressor in common shell
US4519748A (en) * 1982-09-10 1985-05-28 Frick Company Micro-processor control of compression ratio at full load in a helical screw rotary compressor responsive to compressor drive motor current
US4494006A (en) * 1982-09-15 1985-01-15 Compressor Controls Corporation Method and apparatus for controlling a multicompressor station
US4494382A (en) * 1983-10-11 1985-01-22 Carrier Corporation Method and apparatus for controlling when to initiate an increase in compressor capacity
US4614090A (en) * 1985-01-31 1986-09-30 Yanmar Diesel Engine Co. Ltd. Outdoor unit of an air conditioner of an engine heat pump type
US5195329A (en) * 1991-11-12 1993-03-23 Carrier Corporation Automatic chiller plant balancing
US5894739A (en) * 1997-07-10 1999-04-20 York International Corporation Compound refrigeration system for water chilling and thermal storage
US6602057B2 (en) 2001-10-01 2003-08-05 Dresser-Rand Company Management and optimization of load sharing between multiple compressor trains for controlling a main process gas variable
WO2004013494A1 (en) * 2002-08-06 2004-02-12 York International Corporation Stability control system and method for centrifugal compressors operating in parallel
US6772599B2 (en) 2002-08-06 2004-08-10 York International Corporation Stability control system and method for compressors operating in parallel
CN103759482A (zh) * 2007-10-31 2014-04-30 江森自控科技公司 控制气体压缩系统容量的方法以及气体压缩系统
CN103759482B (zh) * 2007-10-31 2016-04-20 江森自控科技公司 控制气体压缩系统容量的方法以及气体压缩系统
EP3156747A4 (en) * 2014-06-10 2018-01-17 Toshiba Carrier Corporation Heat source machine and heat source device
US20220290906A1 (en) * 2019-09-30 2022-09-15 YORK (WUXI) AIR CONDITIONING AND REFRIGERATION Co.,Ltd. Load Balancing Method for Two Compressors
US12196469B2 (en) * 2019-09-30 2025-01-14 York (Wuxi) Air Conditioning And Refrigeration Co., Ltd. Load balancing method for two compressors

Also Published As

Publication number Publication date
DE2147394C2 (de) 1984-04-05
FR2108039B1 (enrdf_load_stackoverflow) 1977-01-21
AU465521B2 (en) 1975-10-02
CA923212A (en) 1973-03-20
AU3289371A (en) 1973-03-08
FR2108039A1 (enrdf_load_stackoverflow) 1972-05-12
IT938839B (it) 1973-02-10
ES395343A1 (es) 1974-12-16
GB1328628A (en) 1973-08-30
DE2147394A1 (de) 1972-03-30

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