GB1564897A

GB1564897A – Gas compression system and method with oil cooling
– Google Patents

GB1564897A – Gas compression system and method with oil cooling
– Google Patents
Gas compression system and method with oil cooling

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Publication number
GB1564897A

GB1564897A
GB39768/75A
GB3976875A
GB1564897A
GB 1564897 A
GB1564897 A
GB 1564897A
GB 39768/75 A
GB39768/75 A
GB 39768/75A
GB 3976875 A
GB3976875 A
GB 3976875A
GB 1564897 A
GB1564897 A
GB 1564897A
Authority
GB
United Kingdom
Prior art keywords
oil
compressor
gas
measured
pressure
Prior art date
1975-09-29
Legal status (The legal status 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 status listed.)

Expired

Application number
GB39768/75A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)

Svenska Rotor Maskiner AB

Original Assignee
Svenska Rotor Maskiner AB
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.)
1975-09-29
Filing date
1975-09-29
Publication date
1980-04-16

1975-09-29
Application filed by Svenska Rotor Maskiner AB
filed
Critical
Svenska Rotor Maskiner AB

1975-09-29
Priority to GB39768/75A
priority
Critical
patent/GB1564897A/en

1976-09-23
Priority to SE7610520A
priority
patent/SE428487B/en

1976-09-28
Priority to DE19762643621
priority
patent/DE2643621A1/en

1976-09-28
Priority to CA262,170A
priority
patent/CA1052588A/en

1976-09-28
Priority to DK436376A
priority
patent/DK147686C/en

1976-09-28
Priority to FR7629163A
priority
patent/FR2325832A1/en

1976-09-29
Priority to US05/728,466
priority
patent/US4112701A/en

1976-09-29
Priority to AU18200/76A
priority
patent/AU510919B2/en

1976-09-29
Priority to IT27795/76A
priority
patent/IT1072580B/en

1976-09-29
Priority to JP51117058A
priority
patent/JPS58590B2/en

1980-04-16
Publication of GB1564897A
publication
Critical
patent/GB1564897A/en

Status
Expired
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

F25B31/002—Lubrication

F25B31/004—Lubrication oil recirculating arrangements

F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING

F04—POSITIVE – DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS

F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS

F04C29/00—Component parts, details or accessories of pumps or pumping installations, not provided for in groups F04C18/00 – F04C28/00

F04C29/0007—Injection of a fluid in the working chamber for sealing, cooling and lubricating

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

Description

PATENT SPECIFICATION () 1 564 897
( 21) Application No 39768/75 ( 22) Filed 29 Sept 1975 ( 23) Complete Specification filed 28 Sept 1976 ( 19)( ( 44) Complete Specification published 16 April 1980 ( 51) INT CL 3 F 04 C 29/02 ( 52) Index at acceptance FIN 2 C ( 54) GAS COMPRESSION SYSTEM AND METHOD WITH OIL COOLING ( 71) We, SVENSKA ROTOR MASKINER AKTIEBOLAG, a Swedish Company of Box 15085, 5-104 65 Stockholm, Sweden, do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by
the following statement:-
The present invention relates to a gas compression system and a method of cooling oil in such a system The invention may be used in various types of plants including the transfer of heat, and particularly in refrigeration plants.
The system comprises a rotary compressor, preferably a screw compressor for the gas, with oil injection into the working space of the compressor.
Screw compressors with oil injection have been used for many years and are well known in the art Such compressors have been used for compression of air and other gases, e g.
hydro carbons such as propane, as well as refrigeration plants using, e g halocarbons such as R 12 and R 22 as refrigerants The oil injected into the compressor has acted as a cooling, sealing and lubricating agent within the compressor and has after the passage of the compressor been separated from the compressed gas in a special oil separator disposed in the discharge line of the compressor The oil separated has then before its introduction into the compressor been cooled down in a special oil cooler, normally with water or air as a cooling agent, in order to increase its viscosity and cooling capacity However, such oil coolers are bulky and expensive and require much maintenance for which reason it has also been suggested to use special oil coolers using the compressed and condensed refrigerant as a cooling agent It has also been suggested to completely eliminate such oil coolers in some application by injection of liquified working fluid into the compressor in order to reduce the discharge temperature of the compressor to such a level that the temperature in the oil separator is decreased to such a value that the oil can be injected without any further cooling thereof.
It has also been found that by combining an oil of a specific type with certain types of gases the cooling of the oil can be dispensed with in certain processes Such processes and the combinations of gases and oils therein are described in U S patent No 3,945,216 In such processes «the working viscosity index» is so high that the viscosity of the oil is practically independent of the temperature within the interval 400 C-100 GC.
In an air conditioning process using R 22, R 502 or R 12 as the rerigerant, and having a compression ratio between 2 to 1 and 5 to 1 and a condensing temperature between 300 C and 500 C the working conditions will be such that the discharge temperature of the compressor will be less than 1000 C in spite of the fact that the oil is not exposed to any cooling, i.e the oil temperature at the injection is practically the same as the discharge temperature of the compressor.
However, in certain applications such as heat pump plants and air conditioning systeins for automotive cars the condensing temperature and/or the pressure ratio is so high that the discharge temperature of the compressor and thus the temperature of the oil falls within the interval 1000 C-150 GC.
The efficiency of the compressor will with those high discharge temperatures be lower than if the oil was cooled down to a temperature below 1000 C, primarily depending upon the losses owing to the increased temperature of the working fluid when brought into contact with the hot oil The magnitude of this decrease of the total adiabatic efficiency will be about 2 % for each c C, so that an increase of the temperature of 50 C results in a decrease in efficiency of about 1 %.
The high temperature may also result in some mechanical problems such as a shorter life of the bearings, increased clearances owing to heat deformation, and problems with the shaft seals It is thus essential that the temperature of the oil is kept at a relatively low level, preferably below 100)C.
The object of the invention is thus to 2 v 1,6 9 2 achieve a simple system and method for reducing the oil temperature.
The invention provides, according to one aspect thereof, a gas compression system comprising an oil separator in a discharge line of the compressor, and an oil supply line to the working space of the compressor connected to the oil separator, the gas and the oil being such that the solubility of the gas in the oil increases with the pressure, wherein a throttling device is provided within the oil supply line from the oil separator to the compressor to reduce the pressure of the oil, and the flow of the oil from the throttling device to the compressor takes a sufficiently long time to allow at least some of the dissolved gas in the oil to be released to decrease the temperature of the oil before the entrance thereof into the compressor.
According to another aspect thereof, the invention provides a method of cooling oil in a gas compression system comprising a rotary compressor for a refrigerant gas, an oil separator in a discharge line of the compressor, and an oil supply line to the working space of the compressor connected to the oil separator, the gas and the oil being such that the solubility of the gas in the oil increases with the pressure, wherein in said method the oil is throttled between the oil separator and the compressor to reduce the pressure of the oil, and the throttled flow of the oil to the compressor takes a sufficiently long time to allow at least some of the dissolved gas in the oil to be released to decrease the temperature of the oil before entrance thereof into the compressor.
The invention will now be discussed in more detail with reference to the annexed drawing which shows a refrigeration system in a diagrammatic way.
In the drawing the compressor 10, is driven by a prime mover 12 The compressed gas is delivered from the compressor through a discharge pipe 14 to an oil separator 16 The oil from the oil separator passes through a pipe 18 and a throttling valve 20 to a wide pipe 22 which communicates with the compressor through a separate inlet 24 The gas from the oil separator passes through a pipe 26 to a condensor 28 from which the working fluid after liquidation passes through a further pipe to an evaporator 32 and back to the compressor 10 At the inlet to the evaporator the liquid passes through an expansion valve 34 which can be connected to a thermostat 36 at the outlet of the evaporator and adjusted in dependence thereupon.
Preferably the refrigerant used in the system has a certain solubility in the oil which is dependant upon the characteristics of the following formula, with respect to the absolute value:
Ine, -flner 15 retri eralt oi where In is the natural logarithm, and where er is the relative capacitivity measured at 500 C of the liquified refrigerant and of the oil, respectively Compare the above mentioned US patent No 3,945,216.
In order to obtain acceptable lubrication and sealing within the compressor the viscosity of the oil must meet the following condition Pl cU v=Y e where v is the kinematic viscosity of the pure oil measured in centistokes (c St) at 500 C.
Y is a constant between 25 and 200, e is the base of the natural system of logarithms, Pl is the discharge pressure of the compressor, u is the tip speed of the male rotor, and c is a constant equal to cm, m 1 kp sec if ‘PT,» is measured in kp/cm 2 and «u» is measured in m/sec.
Compare the above mentioned US patent No 3,945,216.
When both these conditions are met the oil in the oil separator 16, having the same temperature as the discharge temperature of the compressor 10, will contain an amount of refrigerant dissolved therein The oil passes through the pipe 18 to the throttling valve 20, where the oil pressure is reduced from the compressor discharge pressure prevailing in the oil separator to the pressure in the adjoining wide pipe 22 which without restriction is in communication with the working space of the compressor 10 through the port 24 whereby the pressure in the pipe 22 is almost the same as that in the portion of the working space communicating therewith When passing through the valve 20 the pressure of the oil will thus be considerably reduced and it has been found that a considerable amount of the refrigerant dissolved in the oil will boil off from the oil so that the pipe 22 will be filled by a two phase fluid comprising gaseous refrigerant and oil with only a small amount of refrigerant dissolved therein Owing to the boiling off effect the temperature of the oil will be reduced, resulting in a higher viscosity and in increased heat absorbing capacity, whereby the efficiency of the compressor is increased It has further been found that a condition for this reduction of the temperature of the oil and the resulting increase of the efficiency of the compressor is that the time 1,564,897 _ _,_ 6 _97 _ 3 for the oil to flow from the valve 20 to the compressor port 24 falls within the interval 1 sec to 10 sec, preferably about 1 sec.
Especially good test results have been obtained when the pressure drop in the valve 20 was between 2 kp/cm 2 and 20 kp/cm 2.
Dependent upon the degree of solubility of the refrigerant in the oil and the magnitude of the pressure drop in the throttling valve the reduction of the temperature of the oil will then be between 50 C and 200 C.
This system should be compared with the earlier used system where the oil from the oil separator is kept at high pressure all the way up to the compressor where it was injected through narrow holes or nozzles where the pressure difference was obtained.

Claims (16)

WHAT WE CLAIM IS: –

1 A gas compression system comprising a rotary compressor for a refrigerant gas, an oil separator in a discharge line of the compressor and an oil supply line to the working space of the compressor connected to the oil separator, the gas and the oil being such that the solubility of the gas in the oil increases with the pressure, wherein a throttling device is provided within the oil supply line from the oil separator to the compressor to reduce the pressure of the oil, and the flow of the oil from the throttling device to the compressor takes a sufficiently long time to allow at least some of the dissolved gas in the oil to be released to decrease the temperature of the oil before the entrance thereof into the compressor.

2 A system according to claim 1, wherein the relative capacitivities of the gas and the oil are inter-related to meet the following formula Ine r -In,-, 1 < 15 where In is the natural logarithm } is the absolute value, is the relative capacitivity of the liquifled gas measured at 500 C, and E, is the relative capacitivity of the oil measured at 500 C, the kinematic viscosity of the pure oil meets the following formula P, cu v=Y-e where is the kinematic viscosity in centistokes (c St) measured at 50 C, Y is a constant between 25 and 200, e is the base of the natural system of logarithms, P, is the discharge pressure of the compressor, u is the tip speed of the male rotor, and c is a constant equal to cm, m 1 kp sec if "Pi" is measured in kp/cm 2 and "u" is measured in m/sec, and the time for the oil to pass from the throttling device to the compressor is between O 1 sec and sec, preferably about 1 sec. 3 A ssytem according to claim 1 or claim 2, wherein the reduction of the pressure in the throttling device is between 2 kp/cm 2 and 20 kp/cm 2. 4 A system according to any one of claims 1 to 3, wherein the throttling device is a fixed throttling opening. A system according to any one of claims 1 to 3, wherein the throttling device is a variable valve. 6 A system according to any one of claims 1 to 5, wherein the rotary compressor is of the meshing screw rotor type. 7 A system according to any one of claims 1 to 4, or claim 6, wherein the compressor and the oil separator are disposed within a common casing, at least a portion of the oil supply line is shaped as a channel within said casing, and the throttling device is formed as a fixed orifice within said channel. 8 A method of cooling oil in a gas compression system comprising a rotary compressor for a refrigerant gas, an oil separator in a discharge line of the compressor, and an oil supply line to the working space of the compressor connected to the oil separator, the gas and the oil being such that the solubility of the gas in the oil increases with the pressure, wherein in said method the oil is throttled between the oil separator and the compressor to reduce the pressure of the oil, and the throttled flow of the oil to the compressor takes a sufficiently long time to allow at least some of the dissolved gas in the oil to be released to decrease the temperature of the oil before entrance thereof into the compressor. 9 A method according to claim 8, wherein the relative capacitivities of the gas and the oil are inter-lated to meet the following formula finer -Iner J < 1 5 where In is the natural logarithm 1 I is the absolute valve, e, is the relative capacitivity of the liquibas fied gas measured at 50 C, and 1,564,897 1,564,897 er is the relative capacitivity of the oil oil measured at 50 C, the kinematic viscosity of the pure oil meets the following formula Pl C1 U 1 v=Y e where v is the kinematic viscosity in centistokes (c St) measured at 50 C, and Y, e, P 1, u and c are as defined in claim 2. 10 A method according to claim 8 or claim 9, wherein the reduction of the pressure during throttling is between 2 kp/cm 2 and 20 kp/cm 2. 11 A method according to any one of claims 8 to 10, wherein the throttling is produced by a fixed throttling opening. 12 A method according to any one of claims 8 to 10, wherein the throttling is produced by a variable valve. 13 A method according to any one of claims 8 to 12, wherein the rotary compressor is of the meshing screw rotor type. 14 A system according to claim 1, substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawing. A method according to claim 8, substantially as hereinbefore described. 16 A refrigeration system including a gas compression system according to any one of claims 1 to 7 or claim 14. WITHERS & ROGERS, Chartered Patent Agents, 148-150 Holborn, London, EC 1 N 2 NT. Agents from the Applicant. Printed for Her Majesty's Stationery Office, by the Courier Press Leamington Spa, 1980 Published by The Patent Office, 25 Southampton Buildings, London, WC 2 A l AY from which copies may be obtained. - GB39768/75A 1975-09-29 1975-09-29 Gas compression system and method with oil cooling Expired GB1564897A (en) Priority Applications (10) Application Number Priority Date Filing Date Title GB39768/75A GB1564897A (en) 1975-09-29 1975-09-29 Gas compression system and method with oil cooling SE7610520A SE428487B (en) 1975-09-29 1976-09-23 DEVICE FOR COOLING THE OIL IN A GAS COMPRESSOR DE19762643621 DE2643621A1 (en) 1975-09-29 1976-09-28 PROCESS AND ARRANGEMENT FOR COOLING OIL IN A GAS COMPRESSION SYSTEM, IN PARTICULAR A REFRIGERATION SYSTEM CA262,170A CA1052588A (en) 1975-09-29 1976-09-28 Method and means for cooling the oil in a system including a compressor with oil supply, as well as such systems DK436376A DK147686C (en) 1975-09-29 1976-09-28 ARRANGEMENT FOR COOLING THE OIL IN A GAS COMPRESSION PLANT FR7629163A FR2325832A1 (en) 1975-09-29 1976-09-28 METHOD AND DEVICE FOR COOLING THE OIL IN A SYSTEM INCLUDING A COMPRESSOR WITH OIL SUPPLY US05/728,466 US4112701A (en) 1975-09-29 1976-09-29 Method and means for cooling the oil in a system including a compressor with oil supply, as well as such systems AU18200/76A AU510919B2 (en) 1975-09-29 1976-09-29 Compressor cooling system IT27795/76A IT1072580B (en) 1975-09-29 1976-09-29 METHOD AND MEANS FOR COOLING OIL IN A PLANT INCLUDING A COMPRESSOR WITH OIL LIMITATION AND SAID PLANTS JP51117058A JPS58590B2 (en) 1975-09-29 1976-09-29 Oil cooling method and device Applications Claiming Priority (1) Application Number Priority Date Filing Date Title GB39768/75A GB1564897A (en) 1975-09-29 1975-09-29 Gas compression system and method with oil cooling Publications (1) Publication Number Publication Date GB1564897A true GB1564897A (en) 1980-04-16 Family ID=10411381 Family Applications (1) Application Number Title Priority Date Filing Date GB39768/75A Expired GB1564897A (en) 1975-09-29 1975-09-29 Gas compression system and method with oil cooling Country Status (10) Country Link US (1) US4112701A (en) JP (1) JPS58590B2 (en) AU (1) AU510919B2 (en) CA (1) CA1052588A (en) DE (1) DE2643621A1 (en) DK (1) DK147686C (en) FR (1) FR2325832A1 (en) GB (1) GB1564897A (en) IT (1) IT1072580B (en) SE (1) SE428487B (en) Cited By (1) * Cited by examiner, † Cited by third party Publication number Priority date Publication date Assignee Title GB2301629A (en) * 1995-05-25 1996-12-11 Compair Broomwade Ltd Oil recycling in screw compressor arrangements Families Citing this family (9) * Cited by examiner, † Cited by third party Publication number Priority date Publication date Assignee Title DE2822063A1 (en) * 1978-05-20 1979-11-22 Gutehoffnungshuette Sterkrade PROCEDURE FOR OPERATING A SCREW COMPRESSOR US4478054A (en) * 1983-07-12 1984-10-23 Dunham-Bush, Inc. Helical screw rotary compressor for air conditioning system having improved oil management US6116046A (en) * 1999-03-05 2000-09-12 American Standard Inc. Refrigeration chiller with assured start-up lubricant supply US6428296B1 (en) 2001-02-05 2002-08-06 Copeland Corporation Horizontal scroll compressor having an oil injection fitting JP4559241B2 (en) * 2005-01-21 2010-10-06 株式会社神戸製鋼所 Refrigeration equipment US7186099B2 (en) * 2005-01-28 2007-03-06 Emerson Climate Technologies, Inc. Inclined scroll machine having a special oil sump US7566210B2 (en) 2005-10-20 2009-07-28 Emerson Climate Technologies, Inc. Horizontal scroll compressor US8747088B2 (en) * 2007-11-27 2014-06-10 Emerson Climate Technologies, Inc. Open drive scroll compressor with lubrication system CN105649991A (en) * 2015-12-31 2016-06-08 深圳市共济科技有限公司 Variable-frequency air conditioner and compressor oil return system thereof Family Cites Families (10) * Cited by examiner, † Cited by third party Publication number Priority date Publication date Assignee Title US2665557A (en) * 1951-02-03 1954-01-12 Gen Electric Lubricant separating system for refrigerating machines US3079763A (en) * 1962-01-25 1963-03-05 Freezing Equipment Sales Inc Refrigeration DE2052286A1 (en) * 1970-02-27 1972-03-16 VEB Kühlautomat Berlin, χ 1197 Berlin Oil supply on rotary piston compressors GB1384397A (en) * 1971-12-28 1975-02-19 Svenska Rotor Maskiner Ab Refrigeration plants US3795117A (en) * 1972-09-01 1974-03-05 Dunham Bush Inc Injection cooling of screw compressors US3820350A (en) * 1972-12-14 1974-06-28 Stal Refrigeration Ab Rotary compressor with oil cooling JPS5252969Y2 (en) * 1973-05-16 1977-12-01 GB1479451A (en) * 1973-06-18 1977-07-13 Svenska Rotor Maskiner Ab Meshing screw compressors IT1016810B (en) * 1973-08-11 1977-06-20 Miller Allan Sinclair COMPRESSOR FOR PARTICOLARMEN T GAS FOR REFRIGERATION PURPOSES JPS5082607A (en) * 1973-11-26 1975-07-04 1975 1975-09-29 GB GB39768/75A patent/GB1564897A/en not_active Expired 1976 1976-09-23 SE SE7610520A patent/SE428487B/en not_active IP Right Cessation 1976-09-28 CA CA262,170A patent/CA1052588A/en not_active Expired 1976-09-28 FR FR7629163A patent/FR2325832A1/en active Granted 1976-09-28 DK DK436376A patent/DK147686C/en active 1976-09-28 DE DE19762643621 patent/DE2643621A1/en active Granted 1976-09-29 JP JP51117058A patent/JPS58590B2/en not_active Expired 1976-09-29 AU AU18200/76A patent/AU510919B2/en not_active Expired 1976-09-29 IT IT27795/76A patent/IT1072580B/en active 1976-09-29 US US05/728,466 patent/US4112701A/en not_active Expired - Lifetime Cited By (2) * Cited by examiner, † Cited by third party Publication number Priority date Publication date Assignee Title GB2301629A (en) * 1995-05-25 1996-12-11 Compair Broomwade Ltd Oil recycling in screw compressor arrangements GB2301629B (en) * 1995-05-25 1999-02-10 Compair Broomwade Ltd Oil recycling in screw compressor arrangements Also Published As Publication number Publication date US4112701A (en) 1978-09-12 DK147686B (en) 1984-11-12 SE428487B (en) 1983-07-04 IT1072580B (en) 1985-04-10 DE2643621C2 (en) 1987-10-08 AU1820076A (en) 1978-04-06 SE7610520L (en) 1977-03-30 CA1052588A (en) 1979-04-17 FR2325832A1 (en) 1977-04-22 DK436376A (en) 1977-03-30 DK147686C (en) 1985-05-20 AU510919B2 (en) 1980-07-17 JPS58590B2 (en) 1983-01-07 DE2643621A1 (en) 1977-04-07 JPS5256406A (en) 1977-05-09 FR2325832B1 (en) 1983-01-28 Similar Documents Publication Publication Date Title US4497185A (en) 1985-02-05 Oil atomizing compressor working fluid cooling system for gas/vapor/helical screw rotary compressors US3848422A (en) 1974-11-19 Refrigeration plants CN1091862C (en) 2002-10-02 Back pressure control for improved system operative efficiency US3856493A (en) 1974-12-24 Energy recovery system for oil injected screw compressors JPH0237256A (en) 1990-02-07 Improved refrigerator and method of improving efficiency of refrigerator US3913351A (en) 1975-10-21 Air conditioning system having reduced driving requirement GB1564897A (en) 1980-04-16 Gas compression system and method with oil cooling Herbas et al. 1993 Steady‐state simulation of vapour‐compression heat pumps US3931718A (en) 1976-01-13 Refrigerant screw compression with liquid refrigerant injection CN204555461U (en) 2015-08-12 Suction-jet type oil separating device and apply the refrigeration system of this device Jonsson 1991 Performance simulations of twin-screw compressors with economizer JPS5954712A (en) 1984-03-29 Rankine cycle oil return system JPS6032783B2 (en) 1985-07-30 Refrigeration equipment oil return device Tang et al. 1992 Simulation of the working process of an oil flooded helical screw compressor with liquid refrigerant injection US2096255A (en) 1937-10-19 Method of converting solid carbon dioxide to gaseous form and apparatus therefor JPH04203764A (en) 1992-07-24 Freezer device KR870700135A (en) 1987-03-14 Method for Refrigeration System GB1019703A (en) 1966-02-09 Improvements in and relating to refrigeration plant EP0953133A1 (en) 1999-11-03 Heat transport apparatus Eisa et al. 1986 Working fluids for high temperature heat pumps CN209101625U (en) 2019-07-12 A kind of nitrogen cooling device Hood et al. 1964 Helium Refrigerators for Operation in the 10°–30° K Range Mongey et al. 1996 R407C as an alternative to R22 in refrigeration systems Smith et al. 2001 Twin screw machines to replace throttle valves in refrigeration systems. Stosic et al. 2005 An investigation of liquid injection in refrigeration screw compressors Legal Events Date Code Title Description 1980-07-02 PS Patent sealed [section 19, patents act 1949] 1996-05-22 PCNP Patent ceased through non-payment of renewal fee Effective date: 19950928
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