US3408826A - Refrigeration system and systems for cooling and controlling compressors - Google Patents

Refrigeration system and systems for cooling and controlling compressors Download PDF

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Publication number
US3408826A
US3408826A US612222A US61222267A US3408826A US 3408826 A US3408826 A US 3408826A US 612222 A US612222 A US 612222A US 61222267 A US61222267 A US 61222267A US 3408826 A US3408826 A US 3408826A
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United States
Prior art keywords
oil
compressor
gas
valve
refrigerant
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Expired - Lifetime
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US612222A
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English (en)
Inventor
Soumerai Henri
Clark B Hamilton
James R Blatt
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Dunham Bush Inc
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Dunham Bush Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Dunham Bush Inc filed Critical Dunham Bush Inc
Priority to US612222A priority Critical patent/US3408826A/en
Priority to GB46998/70A priority patent/GB1220132A/en
Priority to GB46999/70A priority patent/GB1220133A/en
Priority to GB2606/68A priority patent/GB1220131A/en
Priority to BE709704D priority patent/BE709704A/xx
Priority to DE1601058A priority patent/DE1601058C2/de
Priority to DE19681728619 priority patent/DE1728619A1/de
Priority to CH113768A priority patent/CH483607A/fr
Priority to FR1553294D priority patent/FR1553294A/fr
Priority to NL6801229A priority patent/NL6801229A/xx
Priority to DK32168AA priority patent/DK122415B/da
Application granted granted Critical
Publication of US3408826A publication Critical patent/US3408826A/en
Priority to SE9638/70A priority patent/SE342501B/xx
Anticipated expiration legal-status Critical
Assigned to BT COMMERCIAL CORPORATION reassignment BT COMMERCIAL CORPORATION SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). (ASSIGNS THE ENTIRE INTEREST). Assignors: DUNHAM-BUSH, INC.
Expired - Lifetime legal-status Critical Current

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Classifications

    • 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
    • F25B31/00—Compressor arrangements
    • F25B31/006—Cooling of compressor or motor
    • 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
    • F25B1/00—Compression machines, plants or systems with non-reversible cycle
    • F25B1/04—Compression machines, plants or systems with non-reversible cycle with compressor of rotary type
    • F25B1/047—Compression machines, plants or systems with non-reversible cycle with compressor of rotary type of screw type
    • 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

Definitions

  • An object of thisinvention is to provide an improved refrigeration system. Another object is to provide an improved method and means for operating compressors of the screw type. Another object is to provide. improved means for maintaining desirable operating conditions: in a screw compressor. under varyingv loads andextreme conditions of use. A further object is to provide for the above in a manner which avoids the ditficulties'which have been encountered in the past with similar constructions.
  • FIGURE 1 is a schematic representation of one embodiment of the invention.
  • FIGURE 2 is an enlarged vertical section of the lower left-hand portion of the evaporator-chiller shown at the bottom of FIGURE 1.
  • a refrigeration system 2 includes: a screw compressor 4 having an unloader 5 and driven byan electric motor 6; an oil separator 8; a refrigerant discharge li ne 10; a watercooled condenser 12; a liquid refrigerant line 14 extending to a heat exchanger 16 which acts as a superheater unit; a liquid refrigerant dryer-filter 18;'-a liquid supply control assembly 20 through which the liquid refrigerant flows'to a distributor header 22 for aplurality of liquid distributor tubes 24; an evaporator-chiller 26 having a refrigerant inlet header28 and a refrigerant outlet tube plate 30; and, a gas refrigerant return line 32 through which the gas refrigerant returns to compressor 4.
  • the system also includes an oil circulating system including the following in series: an oil sump 34; an oil pump 36 driven by an electric motor 37; an oil cooler 38 through which water flows from a water' inlet 40.t0 a water outlet 42 and which cools the oil flowing from the pump; and, an oil filter 44.
  • An oil supply line 46 delivers oil under controlled pressure through distributor lines 48 to the motor bearings 50 and through lines 52 and 54 and 56' to compressor 4. Oil is also delivered from line 46 through a line 58 to the unloader 5,'and through a line 59 to a load control unit 60.
  • the dense high-pressure oil-gas mix ture is discharged from compressor 4 into a chamber 62 and thence through the motor where it is discharged axially against a bafile 64.
  • This gas-oil mixture uniform ly blankets and cools the stator and rotor of the motor,
  • 3,408,826 Patented Nov. 5, 1968 and themotor! also serves as -a first-stage oil-separator and-removes, by centrifugal action, the-'bulk'ofthe oil entrained in. the gas. It has been-found-that something of the ordersof 9.5% .of the oil is. removed by the motor, and the. oil'accumulates at 66 in the-bottom of the lion's.- ing-from-which it flows through a line 35 .to oil sump 342 The remaining fine oil'mist is then separated. from the gas by the action of battle 64 and oil separator 8.
  • the disk-like bafile:- 64 deflects the stream" of gas radially outwardly toward the outer-wall and the oil then flows axiallypast the edge of the-battle through a passage- 1 way 68.
  • an annular separatorunit 70 Positioned in. axial alignment with passageway 58 is an annular separatorunit 70 which -effectively removes the oil-.from-the gas passing. through 'it.
  • Unit 70 is a..loosely-formed ring': of: woven rnetal mesh "which is wound upon a perforated tubular-mandrel 72.'-Mandrel 72 forms acentralgas discharge'passageway 74-throu-gh which the gas flows-to a gas discharge tube 73 and thence pasta check valve 75 to. line .10.
  • the gas flowing axially through passageway 68 may proceed in the axial-direction and fiow into and through unit 70, or it may flow radially inwardly through passageway- 76 without restriction into the central passageway 74.
  • the oil from unit 70 adheres to the exposed surfaces of the wire mesh and fiows downwardly and it collects at the bottom of unit 70 in the body of oil 66. It then flows to sump 34 through line 35. During operation there may be a tendency for the oil to bridge some of the passageways between the adjacent lmesh portions in unit 70. Such bridging of the passageways could be expected to cause the oil to be re-entrained in the gas so as to reduce the effectiveness of the oil separator.
  • Chiller 26 has refrigerant tubes 80 which are supported within the shell between their ends and are mounted at their ends in tube plates 82 and 84, respectively (see also FIGURE 2).
  • Tube plates 82 and 84 mounted at their ends in tube plates 82 and 84, respectively (see also FIGURE 2).
  • Mounted upo n tube plate 82 is an orifice plate 86 which is held in place beneath a header 88.
  • Orifice plate 86 has a plurality of small round openings or orifices 90 which are so positioned that one of them is in axial alignment with the end of each of the evaporator tubes 80.
  • Header 88 has a plurality of ribs 92 which rest against orifice plate 86 and divide the area of the orifice plate into a number of header through one -of-thedistributor tubes
  • The-pattern 'of' ribs 92 is such that substantially the same number of orifices 90 is in each of the header chambers 94.
  • the refrigerant supplied to-each of tubes 24 is delivered through one of the headers and its orifices 90 to a specific group of evaporator tubes 80.
  • R'estrictor 142 controls the rate of flow of oil from chamber 130 and therefore frigerant substantially equally to all of the evaporator Controls the rate f movemeht 0f the Piston from a mh i partial-loadposition to the full-load position.
  • a control line 152 extends from other hhuid to he-cooled hows to n m w-93 unit 146 to thedischarge chamber 162 of the compressor through a'pair f lines oo- 102' e f i f as so that unit 146 is responsive to the compressor discharge flowi g h 11. '9 of heat a g -1 cools h pressure.
  • Unit 146 and its valve 148 act as a relief valve liquid refrigerant in coil 104, and the gas then fiows to maintain a p i l e 146 which is a predeterthrough a filt 106 a o h '32 k to mined amount above the pressure in chamber 62.
  • Illuspressor 4 extends from other hhuid to he-cooled hows to n m w-93 unit 146 to thedischarge chamber 162 of the compressor through a'pair f lines oo- 102' e f i
  • the Pressure in line 46 is liquid supply or regulator valves 112 and 114, respectively 240 Pounds Pef'Square ihch- Hence, the Oil delivered to through controllers 116 and 118. Valves 112 and 114' are the compressor through the Various lines 54 and in parallel.
  • Valve 114 is fully' closed at low loads, for 56, and thr0ugh'1ineS'58 an 59 o the unloader is maincham'ple, below 35% f fullload, and valve 112 defeptained at a predetermined value above the compressor dismines the supply ofliquid refrigerant to header 22 below charge Pressure This insures 3 P p and vadequate of full load.
  • valve 114 At loads above 35% of full load valve PP Y l t0 the motor hearings and t0 the compressor- 112 is fully open and the'control is exerted by valve 114.
  • a hot gas bypass line 11 is connected between the gas toward the fully loaded position against the action of the f ig rant discharge line 10 and the liquid supply line 21 oil hd Pressure in h b 130 H h oil i through which liquid refrigerant flows from valves 112 su to h b 139 at a ressure greater than the and 114 todistributor header 22.
  • Line 11 includes a cutdischarge pressure, piston 126 is moved to the left; and, ofii'valve 23 and a restrictor 15.
  • Oil strictor 15 to" prevent Stratification of the liquid phase supply line 58 is connected to chamber 130 through'a and unstable operation of the refrigerant controls.
  • shut-off valve 132 and a line 134 When valve 132 The inventioncontemplates that some of the evaporator is open the oil at the full pressure in lines 46 and 58 is tubes 80 may be supplied with more refrigerant than supplied at once to chamber 130. Also, a flow circuit is others. Such arrangements permit variations in the heat provided in parallel with valve 132 by line 59 and a retransfer or cooling'effect in various zones, Accordingly, strictor valve 136 and a shut-off valve 138.
  • valve 132 when the orifices SN may be of different sizes in any chamber valve 132 is closed and valve 138 is opened, the oil at the 94 and from one chamber to another.
  • various of pressure of line 46 flows through line 59, restrictor 136, the chambers may have different numbers of tubes convalve 138'and line 134 to chamber 130.
  • ren'e'cted to them, with or without variations in the orifice strictor 136 limits the rate of, flow so that piston 126 is size.
  • great freedom of design is provided while moved at a reduced but controlled rate, whereas when valve 132 is open the piston moves at a rapid rate. This permits unloading rapidly by opening valve 132, or unloading at a slower rate by opening valve 138.
  • An additional control circuit is provided by a shut-olf permitting dependableand accurately controlled operation.
  • FIGURE l includes standard components and controls. It is also understood that the embodiment herein disclosed is illustrative, and it is contemplated that f ,5 changesand modifications .may be made within the scope of thexinvention, H v I I ,lNzhat -isclaimed is: ,v v v 1.
  • a compressor having .an unloader means and connectormeans by which it is moved between a fully-loadedposition and fullyeunloaded position, aacylinder and piston assembly operatively connected to said connector means .to move said-unloader: means throughout itspperating range, said compressor and unloader means including means, utilizing force produced bypompressed gas :on the discharge side of the compressor to move said unloader means toward the fully-loaded position against-the unloading-action of said cylinder and piston assembly, an. oil supply means, control means for said cylinder and piston ,assembly including means providing twoparallel flow. paths for oil flowing from fsaid.,oil supply means to: .one endof ,the.
  • said motor separates a substantial portion of the oil from the refrigerant, and which includes an oil separator positioned in axial alignment with the path of gas flow from said motor and including a central bafiie which deflects the gas radially outwardly to an axially directed flow path, said oil separator also including an annular separator-unit positioned in alignment with said annular flow path whereby the-gas impinges against said separator unit, said separator unit being'spaced from said bafiie upon the opposite side-of said motor to provide a free flow path radially inwardly between said separator unit and said baflie and then axially through said unit.
  • a'screw-type compressor having an unloader slide which is moved from and tea full-load position to control the operating capacity, operatingmeans to move said unloader slide throughout its operating range and comprisinga cylinder and piston assembly operatively conh 6 V d I nected to said unloader slide, oil supply means to cool and lubricate said compressor and toprovide oil under pressure to operate said cylindefand piston assembly, and control means to controlthesupplying'of oilj't'o said cylinder and piston assembly including a firsf'valve which is opened to movesaid unloader slide to its fully-unloadd position and a second vane which is opened to provide a fluid flow path from one end to the other ofth'e cylinder of s'aidcylinder and piston-assembly.
  • a screw-type compressor having an unloader slide which is moved to and from a full-load position to control the compressing of refrigerant, said unloader slide being urged 'to its full-load position by the action of the compressed refrigerant
  • aicylinder and piston assembly operati-vely connected to move said unloader slide away from said fullload position under the action of fluid supplied to said cylinder
  • oil supply means connnected to circulate oil through said compressor and also connected to supply oil under pressure to said cylinder, to move said unloader slide away from said full-load position.
  • a refrigeration system the combination of, an electric motor, a compressor connected to said motor and operative to compress the refrigerant in the system, ashell construction enclosing said motor and said compressor and including means forming a passageway through which the compressed refrigerant flows directly from said compressor through said motor, means constituting a con tinuous supply of oil, means to deliver oil from said supply to said compressor with the refrigerant which is being compressed, means to cool said oil prior to passing to said compressor to a temperature which is sufficiently low to permit said motor to be cooled by the refrigerant and accompanying oil flowing therethrough, and means to return the oil passing from said motor to said means constitut- References Cited UNITED STATES PATENTS 2,762,204 9/ 1956 Hanson 62-193 3,041,847 7/1962 Hatter et a1 62193 3,081,604 3/1963 Namisnia-k et al.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Applications Or Details Of Rotary Compressors (AREA)
  • Compressor (AREA)
  • Materials Applied To Surfaces To Minimize Adherence Of Mist Or Water (AREA)
US612222A 1967-01-27 1967-01-27 Refrigeration system and systems for cooling and controlling compressors Expired - Lifetime US3408826A (en)

Priority Applications (12)

Application Number Priority Date Filing Date Title
US612222A US3408826A (en) 1967-01-27 1967-01-27 Refrigeration system and systems for cooling and controlling compressors
GB46998/70A GB1220132A (en) 1967-01-27 1968-01-17 Improvements in or relating to refrigeration systems
GB46999/70A GB1220133A (en) 1967-01-27 1968-01-17 Improvements in or relating to refrigeration systems
GB2606/68A GB1220131A (en) 1967-01-27 1968-01-17 Refrigeration system and systems for cooling and controlling compressors
BE709704D BE709704A (xx) 1967-01-27 1968-01-22
DE19681728619 DE1728619A1 (de) 1967-01-27 1968-01-24 Kuehlsystem mit kompressor und entlastungsventil
DE1601058A DE1601058C2 (de) 1967-01-27 1968-01-24 Motor-Kompressor-Einheit mit Ölabscheider für eine Kälteanlage
CH113768A CH483607A (fr) 1967-01-27 1968-01-25 Installation de réfrigération
FR1553294D FR1553294A (xx) 1967-01-27 1968-01-26
NL6801229A NL6801229A (xx) 1967-01-27 1968-01-26
DK32168AA DK122415B (da) 1967-01-27 1968-01-26 Køleanlæg med en skruekompressor, hvor kompressoren såvel som dennes elektriske drivmotor er indkapslet i en tætsluttende kappe.
SE9638/70A SE342501B (xx) 1967-01-27 1970-12-10

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US612222A US3408826A (en) 1967-01-27 1967-01-27 Refrigeration system and systems for cooling and controlling compressors

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US3408826A true US3408826A (en) 1968-11-05

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US612222A Expired - Lifetime US3408826A (en) 1967-01-27 1967-01-27 Refrigeration system and systems for cooling and controlling compressors

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US (1) US3408826A (xx)
BE (1) BE709704A (xx)
CH (1) CH483607A (xx)
DE (2) DE1601058C2 (xx)
DK (1) DK122415B (xx)
FR (1) FR1553294A (xx)
GB (3) GB1220133A (xx)
NL (1) NL6801229A (xx)
SE (1) SE342501B (xx)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3710590A (en) * 1971-07-19 1973-01-16 Vilter Manufacturing Corp Refrigerant cooled oil system for a rotary screw compressor
US3738116A (en) * 1971-10-01 1973-06-12 Dunham Bush Inc Compressor unloader indicator and refrigeration system controlled thereby
DE2261336A1 (de) * 1971-12-28 1973-07-05 Svenska Rotor Maskiner Ab Kuehlanlage mit einem aussenachsigen drehkolbenverdichter mit schraubenfoermig ineinander eingreifenden maennlichen und weiblichen rotoren
US4091638A (en) * 1976-12-13 1978-05-30 Borg-Warner Corporation Cooling system for hermetic compressor
US4180986A (en) * 1978-04-25 1980-01-01 Dunham-Bush, Inc. Refrigeration system on/off cycle
US5159820A (en) * 1989-07-05 1992-11-03 Nippondenso Co., Ltd. Oil separator integrally mounted on compressor
WO2001018461A1 (en) * 1999-09-03 2001-03-15 American Standard Inc. Prevention of oil backflow from a screw compressor in a refrigeration chiller
US20180017059A1 (en) * 2016-07-13 2018-01-18 Trane International Inc. Variable economizer injection position

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2486207B1 (fr) * 1980-07-07 1987-09-25 Dunham Bush Inc Systeme de pompe a chaleur
GB2161597B (en) * 1984-07-02 1989-04-19 Stewart Colin Minerals Ltd Heating system
DE10145028A1 (de) * 2001-09-13 2003-04-03 Behr Gmbh & Co Kältesystem, insbesondere Kältekreislaufsystem zur Klimatisierung eines Fahrzeugs, und Kühleinrichtung zum Einsatz in einem derartigen Kältesystem
WO2008112554A1 (en) * 2007-03-09 2008-09-18 Johnson Controls Technology Company Refrigeration system
CN107314586B (zh) * 2017-07-20 2023-05-02 爱阔特(上海)清洗设备制造有限公司 一种混蒸油分离装置
CN112113076A (zh) * 2020-09-09 2020-12-22 江西风石压缩机有限公司 一种便于拆修维护的降温式螺杆机组

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2762204A (en) * 1952-12-13 1956-09-11 Carrier Corp Automatic service valves for use in refrigeration systems
US3041847A (en) * 1960-03-21 1962-07-03 Borg Warner Compressor capacity controllers
US3081604A (en) * 1959-05-28 1963-03-19 Carrier Corp Control mechanism for fluid compression means
US3200603A (en) * 1963-11-15 1965-08-17 Carrier Corp Lubricant control means for refrigeration apparatus
US3280576A (en) * 1965-07-26 1966-10-25 Carrier Corp Refrigeration lubrication system and method
US3299655A (en) * 1965-06-01 1967-01-24 Worthington Corp Oil lubrication system for refrigeration apparatus

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB373645A (en) * 1930-02-14 1932-05-17 Lipman Patents Corp Improvements in means for cooling electrically driven rotary compressors of refrigerating apparatus
DE703840C (de) * 1939-03-24 1941-03-17 Siemens Schuckertwerke Akt Ges Einrichtung zur Abfuhr der in einem Motorkompressoraggregat einer Kompressionskaeltemaschine frei werdenden Waerme
DE733969C (de) * 1941-01-07 1943-04-06 Frigera Fabrik Fuer Kuehlanlag Einrichtung zum OElabscheiden aus Kaeltemitteldaempfen bei Tiefkuehlanlagen
US2513912A (en) * 1947-04-23 1950-07-04 Jack & Heintz Prec Ind Inc Compressor
US2597243A (en) * 1949-02-25 1952-05-20 Borg Warner Refrigerator compressor cooling arrangement

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2762204A (en) * 1952-12-13 1956-09-11 Carrier Corp Automatic service valves for use in refrigeration systems
US3081604A (en) * 1959-05-28 1963-03-19 Carrier Corp Control mechanism for fluid compression means
US3041847A (en) * 1960-03-21 1962-07-03 Borg Warner Compressor capacity controllers
US3200603A (en) * 1963-11-15 1965-08-17 Carrier Corp Lubricant control means for refrigeration apparatus
US3299655A (en) * 1965-06-01 1967-01-24 Worthington Corp Oil lubrication system for refrigeration apparatus
US3280576A (en) * 1965-07-26 1966-10-25 Carrier Corp Refrigeration lubrication system and method

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3710590A (en) * 1971-07-19 1973-01-16 Vilter Manufacturing Corp Refrigerant cooled oil system for a rotary screw compressor
US3738116A (en) * 1971-10-01 1973-06-12 Dunham Bush Inc Compressor unloader indicator and refrigeration system controlled thereby
DE2261336A1 (de) * 1971-12-28 1973-07-05 Svenska Rotor Maskiner Ab Kuehlanlage mit einem aussenachsigen drehkolbenverdichter mit schraubenfoermig ineinander eingreifenden maennlichen und weiblichen rotoren
US3811291A (en) * 1971-12-28 1974-05-21 Svenska Rotor Maskiner Ab Method of operating a refrigeration plant and a plant for performing the method
USRE30869E (en) * 1971-12-28 1982-02-23 Svenska Rotor Maskiner Aktiebolag Method of operating a refrigeration plant and a plant for performing the method
US4091638A (en) * 1976-12-13 1978-05-30 Borg-Warner Corporation Cooling system for hermetic compressor
US4180986A (en) * 1978-04-25 1980-01-01 Dunham-Bush, Inc. Refrigeration system on/off cycle
US5159820A (en) * 1989-07-05 1992-11-03 Nippondenso Co., Ltd. Oil separator integrally mounted on compressor
WO2001018461A1 (en) * 1999-09-03 2001-03-15 American Standard Inc. Prevention of oil backflow from a screw compressor in a refrigeration chiller
US20180017059A1 (en) * 2016-07-13 2018-01-18 Trane International Inc. Variable economizer injection position
US10837445B2 (en) * 2016-07-13 2020-11-17 Trane International Inc. Variable economizer injection position
US11959483B2 (en) 2016-07-13 2024-04-16 Trane International Inc. Variable economizer injection position

Also Published As

Publication number Publication date
SE342501B (xx) 1972-02-07
DE1728619A1 (de) 1976-10-21
DE1601058A1 (de) 1970-06-18
DE1601058C2 (de) 1981-10-15
GB1220131A (en) 1971-01-20
BE709704A (xx) 1968-05-30
CH483607A (fr) 1969-12-31
FR1553294A (xx) 1969-01-10
GB1220132A (en) 1971-01-20
DK122415B (da) 1972-02-28
GB1220133A (en) 1971-01-20
NL6801229A (xx) 1968-07-29

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AS Assignment

Owner name: BT COMMERCIAL CORPORATION

Free format text: SECURITY INTEREST;ASSIGNOR:DUNHAM-BUSH, INC. A CORP. OF DE.;REEL/FRAME:004546/0912

Effective date: 19851212