EP3742069B1 - Refrigeration apparatus and use thereof - Google Patents
Refrigeration apparatus and use thereof Download PDFInfo
- Publication number
- EP3742069B1 EP3742069B1 EP19175785.5A EP19175785A EP3742069B1 EP 3742069 B1 EP3742069 B1 EP 3742069B1 EP 19175785 A EP19175785 A EP 19175785A EP 3742069 B1 EP3742069 B1 EP 3742069B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- refrigerant
- lubrication
- flow
- coolant
- outlet
- Prior art date
- 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.)
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- 238000005057 refrigeration Methods 0.000 title claims description 69
- 239000003507 refrigerant Substances 0.000 claims description 232
- 239000002826 coolant Substances 0.000 claims description 175
- 238000005461 lubrication Methods 0.000 claims description 113
- 239000007788 liquid Substances 0.000 claims description 50
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 6
- 238000007599 discharging Methods 0.000 claims description 5
- 238000009795 derivation Methods 0.000 claims description 4
- 230000005484 gravity Effects 0.000 claims description 4
- 239000000314 lubricant Substances 0.000 description 6
- 230000001737 promoting effect Effects 0.000 description 5
- 238000001816 cooling Methods 0.000 description 4
- 238000011144 upstream manufacturing Methods 0.000 description 4
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- 238000013019 agitation Methods 0.000 description 2
- 239000012080 ambient air Substances 0.000 description 2
- 230000006835 compression Effects 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 230000001050 lubricating effect Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000002093 peripheral effect Effects 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- CDOOAUSHHFGWSA-OWOJBTEDSA-N (e)-1,3,3,3-tetrafluoroprop-1-ene Chemical compound F\C=C\C(F)(F)F CDOOAUSHHFGWSA-OWOJBTEDSA-N 0.000 description 1
- 239000003570 air Substances 0.000 description 1
- 238000004378 air conditioning Methods 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
Images
Classifications
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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
- F25B40/00—Subcoolers, desuperheaters or superheaters
- F25B40/02—Subcoolers
-
- 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
-
- 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
- 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
- F04C18/00—Rotary-piston pumps specially adapted for elastic fluids
- F04C18/08—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing
- F04C18/12—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type
- F04C18/14—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type with toothed rotary pistons
- F04C18/16—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type with toothed rotary pistons with helical teeth, e.g. chevron-shaped, screw type
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- 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
- F04C29/02—Lubrication; Lubricant separation
-
- 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
-
- 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
- F25B25/00—Machines, plants or systems, using a combination of modes of operation covered by two or more of the groups F25B1/00 - F25B23/00
- F25B25/005—Machines, plants or systems, using a combination of modes of operation covered by two or more of the groups F25B1/00 - F25B23/00 using primary and secondary systems
-
- 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
- F25B39/00—Evaporators; Condensers
- F25B39/02—Evaporators
-
- 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
- F25B2500/00—Problems to be solved
- F25B2500/16—Lubrication
Definitions
- the present invention concerns a refrigeration apparatus, a refrigeration system comprising such a refrigeration apparatus and the use of said refrigeration apparatus and said refrigeration system.
- the invention relates to the domain of machines that implement a thermodynamic cycle to a refrigerant, for producing a refrigeration effect.
- US 2017/0016651 A1 discloses an energy system capable of heating a refrigerant and lubricant oil in a screw compressor before start-up and cooling the lubricant oil while operating.
- CN109416049A discloses a turbo refrigeration apparatus where the compressor is lubricated by means of refrigerant derived from a liquid refrigerant storage unit formed at the bottom of a condenser.
- CN207035565U discloses an ultra-high temperature heat pump device with heat source recovery, utilizing the heat in a recovery subcooler and an oil cooler.
- WO00/22359A1 discloses a centrifugal refrigeration chiller where refrigerant is supplied at the bearings of the compressor.
- US5884498A1 discloses a turborefrigerator where saturated refrigerant, which is condensed in a condenser, is supercooled by a supercooler and then supplied to a bearing of a turbocompressor for lubrication.
- an example refrigerating apparatus comprising a refrigerant passage including a screw compressor, a condenser, an expansion valve and an evaporator.
- This known apparatus comprises a bypass flow passage, branching at a part of said refrigerant passage, between the condenser and the expansion valve, routing the refrigerant through throttle means, and communicating with a rotor cavity of the screw compressor.
- the refrigerant contains a quantity of lubricant, so that lubrication of the rotor cavity is achieved by the same fluid that is also used as the refrigerant in the passage, and in the absence of oil.
- the refrigerating apparatus For successfully lubricating the rotor cavity, one must ensure that a significant part of the refrigerant reaching the rotor cavity is in a liquid state. This is usually the case when the refrigerating apparatus is operating at high load, corresponding in particular to a high flow of refrigerant. When the refrigerating apparatus is operating at full load, the refrigerant emitted by the condenser is generally entirely in a liquid state, or in a diphasic state with little proportion of the refrigerant in gaseous state.
- the apparatus may be operating at low load, including in particular a smaller flow of refrigerant.
- the refrigerant circulating through the bypass flow passage is not entirely in liquid state and contains a non-negligible proportion of refrigerant in gaseous state, or even a high proportion of refrigerant in gaseous state. Since refrigerant in a gaseous state is not able to sufficiently lubricate the compressor, there is a risk of damaging or destroying the compressor due to a lack of lubrication during low load operation of the apparatus.
- An aim of the invention is to propose a refrigeration apparatus where satisfactory lubrication of the compressor by means of the refrigerant is obtained even during low load operation of the refrigeration apparatus.
- An object of the invention is to provide a refrigeration apparatus as defined by appended independent claim 1, inter alia comprising a main refrigerant circuit, including:
- the main refrigerant circuit is configured for a loop circulation of a main refrigerant flow of a refrigerant, successively through the compressor, the condenser, the expansion valve, and the refrigerant passage.
- the evaporator is configured for enabling an exchange of heat between the main refrigerant flow circulating through the refrigerant passage and a main coolant flow of a coolant circulating through the coolant passage.
- the refrigeration apparatus further comprises a lubrication branch, comprising:
- the refrigeration apparatus further comprises:
- the subcooling heat exchanger comprises: a heat exchange tank, belonging to the lubrication branch and being configured so that the lubrication refrigerant flow circulates through the heat exchange tank; and a heat exchange passage, belonging to the subcooling branch, being positioned within the heat exchange tank and being configured so that the subcooling coolant flow circulates through the heat exchange passage.
- the heat exchange tank comprises at least one liquid level sensor, detecting the presence of liquid refrigerant at a respective height within the heat exchange tank.
- the lubrication refrigerant flow used for lubricating the compressor, is cooled by the subcooling coolant flow through the subcooling heat exchanger, prior to introduction of the lubrication refrigerant flow into the compressor.
- the subcooling heat exchanger ensures that the lubrication refrigerant flow is in liquid form or ensures at least that the lubrication refrigerant flow contains enough refrigerant in liquid form for achieving sufficient lubrication of the compressor.
- the subcooling coolant flow is derived from the main coolant flow at a stage where the coolant is at the lowest temperature, namely at the evaporator or close to the evaporator. Thus, the subcooling coolant flow is at a lower temperature than the lubrication refrigerant flow.
- the invention also concerns a refrigeration system, comprising a refrigeration apparatus as defined above, and comprising a main coolant circuit, including the coolant passage and at least one client device to be cooled by the main coolant flow, the main coolant circuit being configured for loop circulation of the main coolant flow through the main coolant circuit, successively through the coolant passage and said at least one client device, the coolant of the main coolant flow preferably comprising water.
- the invention also concerns a use of the refrigeration apparatus as defined above, or of the refrigeration system as defined above, the use, as defined by appended independent claim 14, including:
- Figure 1 shows a refrigeration system, including a refrigeration apparatus.
- the refrigeration apparatus comprises a main refrigerant circuit 1 forming a closed loop for looped circulation of a main refrigerant flow 90 of refrigerant therein.
- the refrigerant endures a thermodynamic cycle imparted by the components of the main refrigerant circuit 1.
- the refrigerant of the refrigeration apparatus is a fluid material chosen to ensure both functions of refrigerant and lubricant.
- the refrigerant used in the apparatus is a hydrofluoroolefin (HFO), for example R 1234ze (1,3,3,3-tetrafluoroprop-1-ene).
- HFO hydrofluoroolefin
- the refrigeration system comprises a main coolant circuit 70, also designated as "coolant network", forming a closed loop for looped circulation of a main coolant flow 93 therein.
- the main coolant circuit 70 is connected to the refrigeration apparatus.
- the main coolant circuit 70 comprises one client device 72 and forms a single loop.
- the client device 72 is a device which the refrigeration apparatus aims to cool, by retrieving heat from the coolant of the circuit 70 as explained below.
- the client device is a fan coil unit for air conditioning of a building, or is an air handling unit.
- the circuit 70 may comprise one or more circulators, not shown in the figures, for circulating the coolant through the circuit 70.
- the main coolant circuit 70 may comprise several client devices 72 to be fed with coolant of the circuit 70.
- the main coolant circuit 70 may form a loop with derivate branches for feeding the several client devices 72.
- the coolant of the circuit 70 comprises water, or is constituted by water.
- the coolant is preferably always in liquid form, at a temperature comprised for example between 7-12 °C.
- the main refrigerant circuit 1 comprises a compressor 2, a condenser 4, an expansion valve 6 and a refrigerant passage 61.
- the refrigeration apparatus comprises an evaporator 8, through which the refrigerant passage 61 extends at least partially.
- the refrigerant passage 61 may belong to the evaporator 8 and may be entirely comprised within the evaporator 8.
- the compressor 2 comprises a compressor inlet 12 and a compressor outlet 13.
- the condenser 4 includes a condenser inlet 14, connected to the compressor outlet 13, and a condenser outlet 15.
- the expansion valve 6 includes a valve inlet 16, connected to the condenser outlet 15 and a valve outlet 17.
- the passage 61 includes a refrigerant inlet 18, connected to the valve outlet 17, and a refrigerant outlet 19, connected to the compressor inlet 12.
- the inlet 18 is designated as "refrigerant passage inlet”.
- the refrigerant of the flow 90 preferably enters the evaporator 8 by means of the inlet 18.
- the outlet 19 is designated as "refrigerant passage outlet”.
- the refrigerant of the flow 90 preferably exits the evaporator 8 by means of the outlet 19.
- the flow 90 of the aforementioned refrigerant is circulated through the main circuit 1 in a closed loop, successively through the compressor 2, outlet 13, inlet 14, condenser 14, outlet 15, inlet 16, expansion valve 6, outlet 17, inlet 18, refrigerant passage 61, i.e. through the evaporator 8, then outlet 19, inlet 12, and through the compressor 2 again, and so on.
- the refrigerant is compressed by compressor 2.
- the direction of the flow 90 is illustrated by arrows.
- the circulation of the flow 90 of refrigerant through the main circuit 1 is only imparted by the work of the compressor 2.
- additional compressor or pumps may be implemented.
- the main circuit 1 may comprise additional components than the compressor 2, condenser 4, expansion valve 6 and passage 61, for example, an additional expansion valve, or an additional branch for deriving a portion of the flow 90 from a part of the main refrigerant circuit to another part of the main refrigerant circuit, or an additional heat exchanger, that may have an economizer function.
- the low temperature is approximately between 5-10°C
- the high temperature is approximately between 35-40°C
- the low pressure is approximately between 3-4 bar
- the high pressure is approximately between 6-10 bar.
- the main circuit 1 comprises a high-pressure part, consisting in the compressor outlet 13, the condenser 4 and the valve inlet 16, and a low pressure part, consisting in the valve outlet 17, the passage 61 and the compressor inlet 12.
- the main circuit 1 comprises a so-called “supply part", which covers only a portion of the high pressure part, where the refrigerant is mostly in liquid state and high pressure, the supply part preferably consisting in the condenser 4, the valve inlet 16, and any part of the main circuit 1 between the condenser outlet 15 and the valve inlet 16, i.e. downstream from the outlet 15 and upstream from the inlet 16.
- the supply part advantageously constitutes a part of the circuit 1 where the refrigerant of the flow 90 is in the most appropriate state to be used as lubricant.
- the compressor 2 is a positive displacement-type compressor, also called volumetric compressor, such as piston compressor, scroll compressor, roots compressor or screw compressor. More preferably, the compressor 2 is a screw compressor, comprising two parallel meshing screw rotors, for imparting compression to the refrigerant.
- the screw rotors are supported in rotation relative to a frame of the compressor 2 by at least four bearings of the compressor 2, each of the screw rotors being individually supported by two of the four bearings.
- the compressor 2 is equipped with a motor, driving one of the screw rotors in rotation, the second screw rotor being also driven in rotation by meshing with the first screw rotor.
- the compressor 2 is configured to be lubricated by the refrigerant, and not by a separate lubricant.
- the compressor 2 may be qualified as an "oil-free compressor".
- the entire refrigeration apparatus is oil-free.
- the condenser 4 comprises or constitutes a heat exchanger, able to exchange heat between the refrigerant of the main circuit 1 and water, or ambient air, or any other suitable medium able to absorb heat from the main flow 90 of refrigerant circulating through the condenser 4.
- the circuit 70 comprises a coolant passage 71, extending at least partially through the evaporator 8.
- the circuit 70 is thermally linked to the refrigeration apparatus at the evaporator 8 of the refrigeration apparatus.
- the coolant passage 71 may belong to the evaporator 8 and may be entirely comprised within the evaporator 8.
- the coolant passage 71 comprises a coolant inlet 75 and a coolant outlet 76.
- the inlet 75 is designated as "coolant passage inlet”.
- the coolant of the flow 93 preferably enters the evaporator 8 through the inlet 75.
- the outlet 76 is designated as "coolant passage outlet”.
- the coolant of the flow 93 preferably exits the evaporator 8 by means of the outlet 76.
- the devices 72 are fed with the flow 93 of coolant emitted at the outlet 76, and the flow 93 of coolant that has passed through the devices 72 is admitted at the inlet 75.
- the temperature of flow 93 is at the highest, while at the outlet 76, the temperature of the flow 93 is at the lowest, since the coolant was cooled in the evaporator 8.
- the temperature of the coolant is at approximately 12°C at the inlet 75 and at approximately 7°C at the outlet 76.
- the evaporator 8 comprises or constitutes a heat exchanger, configured for enabling heat exchange between the flow 90 of refrigerant circulating though the passage 61 and the flow 93 of coolant circulating through the passage 71.
- the refrigerant of the flow 90 cools the coolant of the flow 93 by exchange of heat with the flow 93 within the evaporator 8.
- Flows 90 and 93 are not brought into contact or mixed together. Instead, the flows 90 and 93 are circulated close to each other with separation by a thin heat-conductive wall of the evaporator 8, provided along passages 61 and 71, promoting heat exchange between the flows 90 and 93.
- the flow 90 retrieves heat from the flow 93 for cooling of said flow 93.
- the flow 90 is heated by the flow 93 within the evaporator 8.
- the refrigeration apparatus comprises a lubrication refrigerant branch 20 distinct from the main refrigerant circuit 1 and from the main coolant circuit 70, and connected to the main refrigerant circuit 1.
- the lubrication branch 20 is a passage for a flow 91 of refrigerant originating from the main refrigerant flow 90 of the main circuit 1.
- the flow 91 is designated as "lubrication refrigerant flow”.
- the lubrication flow 91 is a flow of refrigerant, formed by a portion of the main flow 90.
- the branch 20 comprises an inlet 21, designated as “lubrication inlet” and an outlet 22, designated as “lubrication outlet”.
- the inlet 21 is connected to the main refrigerant circuit 1 at a bottom part 29 of the condenser 4, which belongs to the supply part of the main circuit 1.
- the inlet 21 could be connected for example between the condenser 4 and the expansion valve 6, preferably at the condenser outlet 15.
- any portion of the supply part of the main circuit 1 may be chosen, since, in the supply part of the main circuit 1, at least a part of the refrigerant is in liquid phase.
- the inlet 21 derives the refrigerant flow 91 from the main refrigerant flow 90 that has already circulated through the condenser inlet 14, that has already exchanged heat with the water, ambient air or similar medium through the condenser 4, and that has not yet circulated through the condenser outlet 15. More preferably, the inlet 21 derives the flow 91 at the bottom part 29 of the condenser 4 where liquid-state refrigerant from the flow 90 is received by gravity.
- the inlet 21 derives the flow 91 from the main flow 90 that circulates through the condenser outlet 15, where there is a good chance that most or all of the refrigerant of the flow 90 is in liquid form.
- the flow 91 is introduced into the branch 20 by the inlet 21.
- the outlet 22 is connected to the compressor 2, for feeding the compressor with the lubrication refrigerant flow 91, for lubrication of said compressor 2 by means of the flow 91.
- the outlet 22 is connected at inlets of the compressor 2 that differ from the inlet 12, for feeding mechanical parts of the compressor 2 that require lubrication.
- the outlet 22 is connected to inlets of the compressor 2 that feed the bearings and/or the compression cavities formed by the screw rotors, so that they are lubricated by the liquid refrigerant of the flow 91 fed by the branch 20.
- the branch 20 comprises one or more valves 23, such as solenoid valves and/or throttle valves, for adjusting the flow rate of the flow 91 admitted within the branch 20 and introduced into the compressor 2.
- valves 23 such as solenoid valves and/or throttle valves
- the flow 91 of refrigerant derived at the inlet 21 is usually liquid.
- the refrigerant of the flow 91 may be diphasic at the inlet 21.
- the refrigerant apparatus comprises a subcooling heat exchanger 31 and a subcooling coolant branch 40 for cooling the refrigerant of the flow 91.
- the subcooling coolant branch 40 is distinct from the main refrigerant circuit 1, from the main coolant circuit 70 and from the branch 20.
- the subcooling coolant branch 40 is connected to the main coolant circuit 70.
- the branch 40 is a passage for a flow 92 of coolant, originating from the main coolant flow 93 of the main coolant circuit 70.
- the flow 92 is designated as "subcooling coolant flow”.
- the subcooling coolant flow 92 is a flow of coolant, formed by a portion of the main coolant flow 93.
- the subcooling coolant branch 40 comprises an inlet 41, designated as “subcooling inlet”, and an outlet 42, designated as “subcooling outlet”.
- the inlet 41 is connected to the coolant passage 71 of the main coolant circuit 70, preferably at an exterior part of the evaporator 8 or within the evaporator 8.
- the inlet 41 derives the flow 92 from the flow 93 of coolant which has not yet exchanged heat with the flow 90 of refrigerant within the evaporator 8 but which has already cooled all the client devices 72 of the circuit 70.
- the flow 92 is introduced into the branch 40 by the inlet 41.
- the inlet 41 is connected to the inlet 75 at an exterior location of the evaporator 8.
- the outlet 42 is connected to the coolant passage 71 of the main coolant circuit 70, preferably at an exterior part of the evaporator 8 or within the evaporator 8.
- the outlet 42 reintroduces the derived coolant flow 92 into the coolant flow 93 the main coolant circuit 70, after said coolant flow 93 has exchanged heat with the refrigerant flow 90 in the evaporator 8 and before the coolant flow 93 has cooled any client device 72 from the circuit 70.
- the outlet 42 is connected to the outlet 76 at an exterior location of the evaporator 8.
- the outlet 42 is connected to the circuit 70 downstream relative to the inlet 41.
- the main coolant flow 93 is circulated through the circuit 70, for example by means of a non-shown circulator, connecting the inlet 41 upstream relative to the outlet 42 enables that the subcooling coolant flow 92 is also circulated, without further circulator, since the upstream pressure is higher than the downstream pressure in the passage 71 of the main coolant circuit 70.
- the inlet 41 may be connected at the outlet 76 and the outlet 42 may be connected at the inlet 75.
- a circulator or any other circulation means may be implemented for imparting a circulation of the flow 92 through the branch 40.
- the outlet 42 is connected at a part of passage 71 different from the part of the passage 71 where the inlet 41 is connected.
- the subcooling heat exchanger 31 is configured for enabling or promoting an exchange of heat between the flows 91 and 92, so that the refrigerant of the flow 91 is sub-cooled by exchange of heat with the coolant of the flow 92, within the subcooling heat exchanger 31.
- the flows 91 and 92 are not brought into contact or mixed together. Instead, the flows 91 and 92 are circulated close to each other with separation by a thin heat-conductive wall of the heat exchanger 31, promoting heat exchange between the flows 91 and 92.
- the flow 91 is cooled by the flow 92, and the flow 92 is heated by the flow 91.
- the apparatus ensures that the refrigerant of the lubrication flow 91 is in liquid-state, or has a high proportion of liquid refrigerant, when entering the compressor 2 at the outlet 22. Even when the apparatus operates at low load, i.e. low flow rate of the main refrigerant flow 90, appropriate lubrication of the compressor 2 is ensured.
- the branch 40 may be provided with a suitable valve, such as a throttle valve or solenoid valve, not shown in the figures, for adjusting or disabling the circulation of the flow 92 depending on the current load of the refrigeration apparatus.
- a suitable valve such as a throttle valve or solenoid valve, not shown in the figures, for adjusting or disabling the circulation of the flow 92 depending on the current load of the refrigeration apparatus.
- the circulation of the flow 92 may be interrupted or reduced when the apparatus operates at high load for improving thermal efficiency of the refrigeration apparatus.
- the circulation of the flow 92 may be enabled or increased when the apparatus operates a low load for improving lubrication of the compressor 2.
- the subcooling heat exchanger 31 is positioned outside of the evaporator 8, preferably outside of the main refrigerant circuit 1 and preferably outside of the main coolant circuit 70.
- implementing the heat exchanger 31 in an existing refrigeration system is made easier, since the refrigeration system, including the evaporator 8, does not need to be modified significantly, but only requires appropriate connections with the heat exchanger 31.
- the subcooling heat exchanger 31 comprises a heat exchange tank 32 and a heat exchange passage 33.
- the tank 32 belongs to the branch 20, whereas the heat exchange passage 33 belongs to the branch 40. In other non-shown embodiments not corresponding to the invention, this may be the opposite. More generally, one branch of the refrigeration apparatus, chosen among the lubrication refrigerant branch and the subcooling coolant branch, comprises the tank 32, while the other branch comprises the heat exchange passage 33.
- a quantity of refrigerant for lubrication from the flow 91 is received by the tank 32, allowing easy measuring of the proportion of liquid refrigerant received in the tank 32.
- the liquid refrigerant of the flow 91 received in the tank 32 may constitute a supply of liquid refrigerant that may be used at specific operation stages where little liquid refrigerant is available, for example during starting of the refrigeration apparatus.
- the flow 91 circulates through the tank 32, when circulating in the branch 20 from the inlet 21 to the outlet 22.
- the branch 20 preferably comprises an inlet duct 24, connecting the lubrication inlet 21 to the heat exchange tank 32, for circulation of the lubrication flow 91 from the lubrication inlet 21 to the heat exchange tank 32.
- the duct 24 crosses through a bottom wall of the tank 32 and comprises an open inlet end 25, positioned within the heat exchange tank 32, for admission of the lubrication flow 91 into the heat exchange tank 32 at the vicinity of a top wall of the tank 32.
- the branch 20 also preferably comprises an outlet duct 26, connecting the heat exchange tank 32 to the lubrication outlet 22, for circulation of the lubrication flow 91 from the heat exchange tank 32 to the lubrication outlet 22.
- the duct 26 crosses through the bottom wall of the tank 32 and comprises an open outlet end 27, positioned within the heat exchange tank 32 at the vicinity of the bottom wall of the tank 32, or at the bottom wall of the tank 32.
- the outlet end 27 is at a lower height than the inlet end 25.
- the refrigerant of the flow 91 temporarily rests in the tank 32 where heat is exchanged with the coolant flow 92 received in the passage 33.
- the refrigerant of the flow 91 is either fully liquid, in particular during high load operation of the apparatus, or diphasic, in particular during low load operation of the apparatus.
- diphasic the liquid refrigerant sits at the bottom of the tank 32 while the gaseous refrigerant is located at the top.
- the inlet end 25 is located above the outlet end 27, agitation of the refrigerant of the tank 32 is reduced, avoiding reintroduction of gaseous refrigerant into the liquid refrigerant of the tank 32 if the admitted refrigerant is partially gaseous.
- the outlet end 27 being located at the vicinity of the bottom wall of the tank, the risk of admitting gas bubbles into the outlet end 27 is reduced, even if a level 94 of liquid refrigerant in the tank 32 is low.
- the heat exchange tank 32 comprises at least one liquid level sensor, preferably two liquid level sensors 35 and 36, each configured for detecting the presence of liquid refrigerant within the heat exchange tank 32, at a respective height.
- the sensor 35 is configured to detect the presence of liquid refrigerant in the tank at the same height than, or slightly above, the outlet end 27. Thus, the sensor 35 may be used for detecting when the amount of available liquid refrigerant in the tank 32 is too low for correct lubrication of the compressor 2 in steady-state of the refrigerating apparatus, for example during low load operation of the refrigerating apparatus.
- the sensor 36 is configured to detect the presence of liquid refrigerant in the tank 32 at a higher height than the sensor 35, between the height of the end 25 and the height of the end 27.
- the sensor 36 may be used for detecting when the amount of available liquid refrigerant in the tank 32 is above or below an acceptable level for starting the refrigerating apparatus, which may require that a high amount of liquid refrigerant is available in the tank 32 for lubrication of the compressor 2.
- the level 94 of liquid refrigerant received within the tank 32 is at a height comprised between sensors 35 and 36, so that only sensor 35 detects the presence of liquid refrigerant.
- the tank 32 comprises a number of liquid level sensors different than two, each detecting the presence of liquid refrigerant in the tank 32 at a respective height.
- the heat exchange passage 33 is positioned within the heat exchange tank 32, so as to be surrounded by the refrigerant of the flow 91.
- the passage 33 is configured so that the coolant flow 92 circulating through the branch 40 circulates through the passage 33, when circulating from the inlet 41 to the outlet 42.
- the passage 33 is a coil duct, promoting heat exchange.
- the coil duct is preferably made of a material with high heat conductivity such as copper or the like.
- the coil duct has the advantage that it does not induce too much pressure drop for the flow 92 flowing through.
- any other suitable shape may be implemented for the passage 33, promoting heat exchange without inducing too much pressure drop of the flow 92 and too much agitation for the flow 91 sitting in the tank 32.
- the heat exchange passage 33 comprises a coolant inlet 43, connected to the subcooling inlet 41 by an inlet duct of the branch 40.
- the heat exchange passage 33 comprises a coolant outlet 44, connected to the subcooling outlet 42 by an outlet duct of the branch 40.
- the inlet 43 and the outlet 44 are preferably positioned at a peripheral wall of the heat exchange tank 32.
- the peripheral wall is preferably vertical, and connects the top wall to the bottom wall of the tank 32.
- the inlet 43 is preferably at a different height, such as a lower height, than the outlet 44, as shown in figure 2 .
- the coil duct of the passage 33, connecting the inlet 43 to the outlet 44, is preferably vertical overall.
- the inlet 43 is preferably connected to the tank 31 at the bottom of the tank 31, or at least at the vicinity of the outlet 27, so that the flow 92 entering the heat exchange passage 33 is close to the outlet 27.
- the heat exchanger 32 is preferably a counterflow heat exchanger.
- the heat exchange tank 32 and in particular the open outlet end 27, is positioned at a higher height than the compressor 2, so that the compressor is fed with the lubrication refrigerant flow 91 under the effect of gravity.
- the need for a circulator for circulating the flow 91 is reduced.
- the evaporator 8 is a flooded heat exchanger, such as a flooded tube heat exchanger.
- the refrigerant passage 61 comprises a tank, designated as "evaporator tank", receiving the refrigerant from the flow 90 of the main refrigerant circuit 1.
- the tank 61 is of generally cylindrical shape, as this is the case in figure 2 .
- the inlet 18 is preferably connected at the bottom of the tank 61 for admission of the flow 90 into the tank 61 by the bottom thereof.
- the outlet 19 is preferably connected at the top of the tank 61 for discharging of the flow 90 into the tank 61 by the top thereof.
- the refrigerant of the flow 90 received within the tank 61 is advantageously in diphasic form, so that the liquid part of the received refrigerant sits at the bottom of the tank 61, whereas the gaseous part of the received refrigerant evaporates towards the top of the tank 61, when receiving heat from the coolant flow 93 circulating through the coolant passage 71.
- the coolant passage 71 comprises a heat exchange duct, as depicted in figure 2 , crossing through the evaporator tank 61 so as to be surrounded by the refrigerant received in the tank 61.
- the coolant flow 93 flows through the heat exchange duct 71 so that heat is exchanged between said coolant flow 93 and the refrigerant flow 90 received within the tank 61.
- one end of the exchange duct 71 is connected to the inlet 75 whereas the other end of the exchange duct 71 is connected to the outlet 76.
- the heat exchange duct 71 is preferably made of a heat conductive material, such as copper or the like, so as to promote exchange of heat between the flows 90 and 93.
- the heat exchange duct 71 may be in the form of a coil duct.
- the coolant passage 71 may comprise several heat exchange ducts, each connected to the inlet 75 and 76, each crossing through the tank 61 so as to be surrounded with the refrigerant of the main circuit 1 received within the tank 61, and each circulated by a portion of the flow 93.
- valves 23, when both closed, may also be used for temporarily storing refrigerant within the branch 20, in particular within the tank 32 of the heat exchanger 31, especially for periods of time when the refrigeration apparatus is stopped, allowing that liquid-state refrigerant is available in the tank 31 before re-starting.
- one valve 23 is positioned upstream from the tank 32 and the other valve 23 is positioned downstream of from tank 32.
- the subcooling inlet and the subcooling outlet is positioned within the evaporator tank 61, preferably the subcooling inlet.
- the subcooling coolant flow 92 is derived from the part of the coolant passage 71 extending within the evaporator tank 61, namely the heat exchange duct.
- the derived subcooling coolant flow 92 is at a lower temperature, which may be useful at starting of the refrigeration apparatus.
- two subcooling inlets may be provided for deriving the flow 92, one connected to the inlet 75 and the other connected to the heat exchange duct 71.
- the branch 40 may be provided with appropriate valves for selecting by means of which of the subcooling inlets the flow 92 is derived, depending on the operation stage of the refrigeration apparatus.
- the refrigerant passage of the evaporator constitutes the heat exchange duct whereas the coolant passage of the evaporator constitutes the evaporator tank.
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Lubricants (AREA)
- Other Air-Conditioning Systems (AREA)
- Compression-Type Refrigeration Machines With Reversible Cycles (AREA)
Description
- The present invention concerns a refrigeration apparatus, a refrigeration system comprising such a refrigeration apparatus and the use of said refrigeration apparatus and said refrigeration system.
- The invention relates to the domain of machines that implement a thermodynamic cycle to a refrigerant, for producing a refrigeration effect.
-
US 2017/0016651 A1 discloses an energy system capable of heating a refrigerant and lubricant oil in a screw compressor before start-up and cooling the lubricant oil while operating. -
CN109416049A discloses a turbo refrigeration apparatus where the compressor is lubricated by means of refrigerant derived from a liquid refrigerant storage unit formed at the bottom of a condenser. -
CN207035565U discloses an ultra-high temperature heat pump device with heat source recovery, utilizing the heat in a recovery subcooler and an oil cooler. -
WO00/22359A1 -
US5884498A1 discloses a turborefrigerator where saturated refrigerant, which is condensed in a condenser, is supercooled by a supercooler and then supplied to a bearing of a turbocompressor for lubrication. - Further, an example refrigerating apparatus is also known from
EP 1 400 765 A2 - For successfully lubricating the rotor cavity, one must ensure that a significant part of the refrigerant reaching the rotor cavity is in a liquid state. This is usually the case when the refrigerating apparatus is operating at high load, corresponding in particular to a high flow of refrigerant. When the refrigerating apparatus is operating at full load, the refrigerant emitted by the condenser is generally entirely in a liquid state, or in a diphasic state with little proportion of the refrigerant in gaseous state.
- However, if the need for refrigeration is lower, the apparatus may be operating at low load, including in particular a smaller flow of refrigerant. During low load operation of the apparatus, it may happen that the refrigerant circulating through the bypass flow passage is not entirely in liquid state and contains a non-negligible proportion of refrigerant in gaseous state, or even a high proportion of refrigerant in gaseous state. Since refrigerant in a gaseous state is not able to sufficiently lubricate the compressor, there is a risk of damaging or destroying the compressor due to a lack of lubrication during low load operation of the apparatus.
- An aim of the invention is to propose a refrigeration apparatus where satisfactory lubrication of the compressor by means of the refrigerant is obtained even during low load operation of the refrigeration apparatus.
- An object of the invention is to provide a refrigeration apparatus as defined by appended
independent claim 1, inter alia comprising a main refrigerant circuit, including: - a compressor, including a compressor inlet and a compressor outlet,
- a condenser, including a condenser inlet, connected to the compressor outlet, and a condenser outlet,
- an expansion valve, including a valve inlet, connected to the condenser outlet and a valve outlet, and
- a refrigerant passage, extending at least partially within an evaporator of the refrigeration apparatus, the refrigerant passage including a refrigerant passage inlet, connected to the valve outlet, and a refrigerant passage outlet, connected to the compressor inlet, the refrigeration apparatus also including a coolant passage extending at least partially within the evaporator and including a coolant passage inlet and a coolant passage outlet.
- According to the invention the main refrigerant circuit is configured for a loop circulation of a main refrigerant flow of a refrigerant, successively through the compressor, the condenser, the expansion valve, and the refrigerant passage.
- According to the invention the evaporator is configured for enabling an exchange of heat between the main refrigerant flow circulating through the refrigerant passage and a main coolant flow of a coolant circulating through the coolant passage.
- According to the invention the refrigeration apparatus further comprises a lubrication branch, comprising:
- a lubrication inlet, connected to a supply part of the main circuit, the supply part consisting in the condenser, the valve inlet, and any part of the main circuit between the condenser outlet and the valve inlet, the lubrication inlet being configured to derive a lubrication refrigerant flow from the main refrigerant flow circulating through the supply part; and
- a lubrication outlet, connected to the compressor so as to feed the compressor with the lubrication refrigerant flow, for lubrication of said compressor with the refrigerant of the lubrication refrigerant flow.
- According to the invention, the refrigeration apparatus further comprises:
- a subcooling branch, comprising:
- oa subcooling inlet, connected to the coolant passage, so as to derive a subcooling coolant flow from the main coolant flow, and
- oa subcooling outlet, connected to the coolant passage, for reintroducing the subcooling coolant flow into the main coolant flow; and
- a subcooling heat exchanger, being configured for enabling an exchange of heat between the subcooling coolant flow circulating through the subcooling branch and the lubrication refrigerant flow circulating through the lubrication branch, so that the lubrication refrigerant flow may be cooled by the subcooling coolant flow within the subcooling heat exchanger.
- According to the invention, the subcooling heat exchanger comprises: a heat exchange tank, belonging to the lubrication branch and being configured so that the lubrication refrigerant flow circulates through the heat exchange tank; and a heat exchange passage, belonging to the subcooling branch, being positioned within the heat exchange tank and being configured so that the subcooling coolant flow circulates through the heat exchange passage.
- According to the invention, the heat exchange tank comprises at least one liquid level sensor, detecting the presence of liquid refrigerant at a respective height within the heat exchange tank.
- Thanks to the invention, the lubrication refrigerant flow, used for lubricating the compressor, is cooled by the subcooling coolant flow through the subcooling heat exchanger, prior to introduction of the lubrication refrigerant flow into the compressor. Thus, the subcooling heat exchanger ensures that the lubrication refrigerant flow is in liquid form or ensures at least that the lubrication refrigerant flow contains enough refrigerant in liquid form for achieving sufficient lubrication of the compressor. The subcooling coolant flow is derived from the main coolant flow at a stage where the coolant is at the lowest temperature, namely at the evaporator or close to the evaporator. Thus, the subcooling coolant flow is at a lower temperature than the lubrication refrigerant flow.
- Further advantageous features of the invention are defined below:
- The subcooling inlet is connected to a coolant passage inlet of the coolant passage, so as to derive the subcooling coolant flow from the main coolant flow circulating through the coolant passage inlet, and the subcooling outlet is connected to a coolant passage outlet of the coolant passage, for reintroducing the subcooling coolant flow into the main coolant flow circulating through the coolant passage outlet.
- The refrigerant passage comprises an evaporator tank of the evaporator, the evaporator tank being connected to the refrigerant passage inlet, for admitting the main refrigerant flow into the evaporator tank, and to the refrigerant passage outlet, for discharging the main refrigerant flow from the evaporator tank ; and the coolant passage comprises at least one heat exchange duct of the evaporator, the heat exchange duct extending within the evaporator tank so as to be surrounded by the main refrigerant flow received within the evaporator tank, the heat exchange duct being connected to the coolant passage inlet, for admitting the main coolant flow into the heat exchange duct, and to the coolant passage outlet, for discharging of the main coolant flow from the heat exchange duct.
- The subcooling heat exchanger is positioned outside of the evaporator.
- The lubrication branch comprises: an inlet duct, connecting the lubrication inlet to the heat exchange tank, for circulation of the lubrication refrigerant flow from the lubrication inlet to the heat exchange tank, and comprising an open inlet end positioned within the heat exchange tank for admission of the lubrication refrigerant flow into the heat exchange tank; and an outlet duct, connecting the heat exchange tank to the lubrication outlet, for circulation of the lubrication refrigerant flow from the heat exchange tank to the lubrication outlet, and comprising an open outlet end positioned within the heat exchange tank, at a lower height than the open inlet end.
- The heat exchange tank is positioned at a higher height than the lubrication outlet, so that the compressor is fed with the lubrication refrigerant flow by gravity.
- The heat exchange passage is a coil duct.
- For being connected to the supply part, the lubrication inlet is connected to a bottom part of the condenser.
- The compressor is a positive displacement-type compressor.
- The compressor is a screw compressor comprising two meshing screw rotors and bearings, the screw-rotors being supported by the bearings, and the lubrication outlet is connected to the compressor so as to feed the bearings and the screw rotors with the lubrication refrigerant flow, for lubrication of said bearings and screw rotors.
- The invention also concerns a refrigeration system, comprising a refrigeration apparatus as defined above, and comprising a main coolant circuit, including the coolant passage and at least one client device to be cooled by the main coolant flow, the main coolant circuit being configured for loop circulation of the main coolant flow through the main coolant circuit, successively through the coolant passage and said at least one client device, the coolant of the main coolant flow preferably comprising water.
- The invention also concerns a use of the refrigeration apparatus as defined above, or of the refrigeration system as defined above, the use, as defined by appended
independent claim 14, including: - closed loop circulation of the main refrigerant flow successively through the compressor inlet, the compressor, the compressor outlet, the condenser inlet, the condenser, the condenser outlet, the valve inlet, the expansion valve, the valve outlet, the refrigerant passage inlet, the refrigerant passage, and the refrigerant passage outlet;
- derivation of the lubrication refrigerant flow from the main refrigerant flow circulating through the supply part, by the lubrication inlet,
- circulation of the lubrication refrigerant flow through the lubrication branch, successively through the lubrication inlet, the subcooling heat exchanger and the lubrication outlet,
- derivation of the subcooling coolant flow from the main coolant flow circulating through the coolant passage, by the subcooling inlet,
- circulation of the subcooling coolant flow through the subcooling branch, successively through the subcooling inlet, the subcooling heat exchanger and the subcooling outlet,
- exchange of heat between the subcooling coolant flow and the lubrication refrigerant flow in the subcooling heat exchanger, so that the lubrication refrigerant flow is cooled by the subcooling coolant flow,
- feeding of the compressor, by the lubrication outlet, with the lubrication refrigerant flow that was cooled by the subcooling coolant flow in the subcooling heat exchanger, for lubrication of the compressor, and
- reintroduction, by the subcooling outlet, of the subcooling coolant flow that has cooled the lubrication refrigerant flow in the subcooling heat exchanger, into the main coolant flow circulating through the coolant passage.
- Exemplary embodiments according to the invention and including further advantageous features of the invention are explained below, referring to the attached drawings, wherein:
-
figure 1 is a synoptic drawing showing an embodiment of a refrigeration system, including a refrigeration apparatus according to the invention; -
figure 2 is a synoptic drawing showing only a part of the refrigeration apparatus offigure 1 . -
Figure 1 shows a refrigeration system, including a refrigeration apparatus. The refrigeration apparatus comprises amain refrigerant circuit 1 forming a closed loop for looped circulation of amain refrigerant flow 90 of refrigerant therein. During the circulation of the main refrigerant flow 90 of refrigerant through themain refrigerant circuit 1, the refrigerant endures a thermodynamic cycle imparted by the components of themain refrigerant circuit 1. - The refrigerant of the refrigeration apparatus is a fluid material chosen to ensure both functions of refrigerant and lubricant. Preferably, the refrigerant used in the apparatus is a hydrofluoroolefin (HFO), for example R 1234ze (1,3,3,3-tetrafluoroprop-1-ene).
- In addition to the refrigeration apparatus, the refrigeration system comprises a
main coolant circuit 70, also designated as "coolant network", forming a closed loop for looped circulation of amain coolant flow 93 therein. Themain coolant circuit 70 is connected to the refrigeration apparatus. In the embodiment offigures 1 and2 , themain coolant circuit 70 comprises oneclient device 72 and forms a single loop. Theclient device 72 is a device which the refrigeration apparatus aims to cool, by retrieving heat from the coolant of thecircuit 70 as explained below. For example, the client device is a fan coil unit for air conditioning of a building, or is an air handling unit. Thecircuit 70 may comprise one or more circulators, not shown in the figures, for circulating the coolant through thecircuit 70. - In an alternative embodiment, the
main coolant circuit 70 may compriseseveral client devices 72 to be fed with coolant of thecircuit 70. In this case, themain coolant circuit 70 may form a loop with derivate branches for feeding theseveral client devices 72. - Preferably, the coolant of the
circuit 70 comprises water, or is constituted by water. In the refrigeration system, the coolant is preferably always in liquid form, at a temperature comprised for example between 7-12 °C. - The main
refrigerant circuit 1 comprises acompressor 2, acondenser 4, anexpansion valve 6 and arefrigerant passage 61. The refrigeration apparatus comprises anevaporator 8, through which therefrigerant passage 61 extends at least partially. Therefrigerant passage 61 may belong to theevaporator 8 and may be entirely comprised within theevaporator 8. Thecompressor 2 comprises acompressor inlet 12 and acompressor outlet 13. Thecondenser 4 includes acondenser inlet 14, connected to thecompressor outlet 13, and acondenser outlet 15. Theexpansion valve 6 includes avalve inlet 16, connected to thecondenser outlet 15 and avalve outlet 17. Thepassage 61 includes arefrigerant inlet 18, connected to thevalve outlet 17, and arefrigerant outlet 19, connected to thecompressor inlet 12. Theinlet 18 is designated as "refrigerant passage inlet". The refrigerant of theflow 90 preferably enters theevaporator 8 by means of theinlet 18. Theoutlet 19 is designated as "refrigerant passage outlet". The refrigerant of theflow 90 preferably exits theevaporator 8 by means of theoutlet 19. - For obtaining the thermodynamic cycle of the refrigerant, the
flow 90 of the aforementioned refrigerant is circulated through themain circuit 1 in a closed loop, successively through thecompressor 2,outlet 13,inlet 14,condenser 14,outlet 15,inlet 16,expansion valve 6,outlet 17,inlet 18,refrigerant passage 61, i.e. through theevaporator 8, thenoutlet 19,inlet 12, and through thecompressor 2 again, and so on. For this purpose, the refrigerant is compressed bycompressor 2. In the figures, the direction of theflow 90 is illustrated by arrows. - Preferably, the circulation of the
flow 90 of refrigerant through themain circuit 1 is only imparted by the work of thecompressor 2. However, if necessary, additional compressor or pumps may be implemented. More generally, depending on the application, themain circuit 1 may comprise additional components than thecompressor 2,condenser 4,expansion valve 6 andpassage 61, for example, an additional expansion valve, or an additional branch for deriving a portion of theflow 90 from a part of the main refrigerant circuit to another part of the main refrigerant circuit, or an additional heat exchanger, that may have an economizer function. - Preferably, in a steady-state, during a high load operation of the refrigerating apparatus:
- in the
compressor 2, the refrigerant is in a gaseous state, and is compressed from a low pressure to a high pressure, which raises the temperature of the refrigerant from a low temperature to a high temperature; - in the
outlet 13 and in theinlet 14, the refrigerant is in a gaseous state, or essentially gaseous state, is at the high temperature and the high pressure; - in the
condenser 4, the refrigerant is in a diphasic state, including gaseous and liquid refrigerant, and is condensed to a liquid state by thecondenser 4; - in the
outlet 15 and in theinlet 16, the refrigerant is in a liquid state, or essentially liquid state, is at the high pressure, and may be at the high temperature or at a temperature between the high temperature and the low temperature; - in the
expansion valve 6, the refrigerant is brought to the low pressure, which lowers the temperature of the refrigerant to the low temperature while evaporating the refrigerant to the diphasic state; - in the
outlet 17 and in theinlet 18, the refrigerant is in a diphasic-state, where a major part is liquid and a smaller part is gaseous, and the refrigerant is at the low temperature and the low pressure; - in the
passage 61, through theevaporator 8, the refrigerant is in a diphasic state, including gaseous and liquid refrigerant, and is evaporated to a gaseous state by theevaporator 8; - in the
outlet 19 and in theinlet 12, the refrigerant is in a gaseous state, or essentially gaseous state, at the low pressure and at a low temperature, or at a temperature between the low and the high temperature. - For example, the low temperature is approximately between 5-10°C, the high temperature is approximately between 35-40°C, the low pressure is approximately between 3-4 bar, and the high pressure is approximately between 6-10 bar.
- Considering the above, the
main circuit 1 comprises a high-pressure part, consisting in thecompressor outlet 13, thecondenser 4 and thevalve inlet 16, and a low pressure part, consisting in thevalve outlet 17, thepassage 61 and thecompressor inlet 12. - The
main circuit 1 comprises a so-called "supply part", which covers only a portion of the high pressure part, where the refrigerant is mostly in liquid state and high pressure, the supply part preferably consisting in thecondenser 4, thevalve inlet 16, and any part of themain circuit 1 between thecondenser outlet 15 and thevalve inlet 16, i.e. downstream from theoutlet 15 and upstream from theinlet 16. The supply part advantageously constitutes a part of thecircuit 1 where the refrigerant of theflow 90 is in the most appropriate state to be used as lubricant. - Preferably, the
compressor 2 is a positive displacement-type compressor, also called volumetric compressor, such as piston compressor, scroll compressor, roots compressor or screw compressor. More preferably, thecompressor 2 is a screw compressor, comprising two parallel meshing screw rotors, for imparting compression to the refrigerant. The screw rotors are supported in rotation relative to a frame of thecompressor 2 by at least four bearings of thecompressor 2, each of the screw rotors being individually supported by two of the four bearings. Thecompressor 2 is equipped with a motor, driving one of the screw rotors in rotation, the second screw rotor being also driven in rotation by meshing with the first screw rotor. - The
compressor 2 is configured to be lubricated by the refrigerant, and not by a separate lubricant. Thus, thecompressor 2 may be qualified as an "oil-free compressor". Preferably, the entire refrigeration apparatus is oil-free. - Preferably, the
condenser 4 comprises or constitutes a heat exchanger, able to exchange heat between the refrigerant of themain circuit 1 and water, or ambient air, or any other suitable medium able to absorb heat from themain flow 90 of refrigerant circulating through thecondenser 4. - For the refrigeration apparatus to ensure cooling of the coolant of the
circuit 70, thecircuit 70 comprises acoolant passage 71, extending at least partially through theevaporator 8. Thus, thecircuit 70 is thermally linked to the refrigeration apparatus at theevaporator 8 of the refrigeration apparatus. Thecoolant passage 71 may belong to theevaporator 8 and may be entirely comprised within theevaporator 8. - The
coolant passage 71 comprises acoolant inlet 75 and acoolant outlet 76. Theinlet 75 is designated as "coolant passage inlet". The coolant of theflow 93 preferably enters theevaporator 8 through theinlet 75. Theoutlet 76 is designated as "coolant passage outlet". The coolant of theflow 93 preferably exits theevaporator 8 by means of theoutlet 76. Thedevices 72 are fed with theflow 93 of coolant emitted at theoutlet 76, and theflow 93 of coolant that has passed through thedevices 72 is admitted at theinlet 75. - Preferably, at the
inlet 75, the temperature offlow 93 is at the highest, while at theoutlet 76, the temperature of theflow 93 is at the lowest, since the coolant was cooled in theevaporator 8. For example, the temperature of the coolant is at approximately 12°C at theinlet 75 and at approximately 7°C at theoutlet 76. - The
evaporator 8 comprises or constitutes a heat exchanger, configured for enabling heat exchange between theflow 90 of refrigerant circulating though thepassage 61 and theflow 93 of coolant circulating through thepassage 71. In theevaporator 8, the refrigerant of theflow 90 cools the coolant of theflow 93 by exchange of heat with theflow 93 within theevaporator 8. Flows 90 and 93 are not brought into contact or mixed together. Instead, theflows evaporator 8, provided alongpassages flows evaporator 8, theflow 90 retrieves heat from theflow 93 for cooling of saidflow 93. Thus, theflow 90 is heated by theflow 93 within theevaporator 8. - The refrigeration apparatus comprises a
lubrication refrigerant branch 20 distinct from the mainrefrigerant circuit 1 and from themain coolant circuit 70, and connected to the mainrefrigerant circuit 1. Thelubrication branch 20 is a passage for aflow 91 of refrigerant originating from themain refrigerant flow 90 of themain circuit 1. Theflow 91 is designated as "lubrication refrigerant flow". Thelubrication flow 91 is a flow of refrigerant, formed by a portion of themain flow 90. - The
branch 20 comprises aninlet 21, designated as "lubrication inlet" and anoutlet 22, designated as "lubrication outlet". Theinlet 21 is connected to the mainrefrigerant circuit 1 at abottom part 29 of thecondenser 4, which belongs to the supply part of themain circuit 1. Alternatively, theinlet 21 could be connected for example between thecondenser 4 and theexpansion valve 6, preferably at thecondenser outlet 15. Alternatively, for connection of theinlet 21, any portion of the supply part of themain circuit 1 may be chosen, since, in the supply part of themain circuit 1, at least a part of the refrigerant is in liquid phase. - Preferably, the
inlet 21 derives therefrigerant flow 91 from themain refrigerant flow 90 that has already circulated through thecondenser inlet 14, that has already exchanged heat with the water, ambient air or similar medium through thecondenser 4, and that has not yet circulated through thecondenser outlet 15. More preferably, theinlet 21 derives theflow 91 at thebottom part 29 of thecondenser 4 where liquid-state refrigerant from theflow 90 is received by gravity. - In a preferred alternative, the
inlet 21 derives theflow 91 from themain flow 90 that circulates through thecondenser outlet 15, where there is a good chance that most or all of the refrigerant of theflow 90 is in liquid form. - The
flow 91 is introduced into thebranch 20 by theinlet 21. Theoutlet 22 is connected to thecompressor 2, for feeding the compressor with thelubrication refrigerant flow 91, for lubrication of saidcompressor 2 by means of theflow 91. Theoutlet 22 is connected at inlets of thecompressor 2 that differ from theinlet 12, for feeding mechanical parts of thecompressor 2 that require lubrication. Preferably, theoutlet 22 is connected to inlets of thecompressor 2 that feed the bearings and/or the compression cavities formed by the screw rotors, so that they are lubricated by the liquid refrigerant of theflow 91 fed by thebranch 20. - Optionally, the
branch 20 comprises one ormore valves 23, such as solenoid valves and/or throttle valves, for adjusting the flow rate of theflow 91 admitted within thebranch 20 and introduced into thecompressor 2. - As explained above, during high load operation of the apparatus, the
flow 91 of refrigerant derived at theinlet 21 is usually liquid. However, at a lower load of the apparatus, the refrigerant of theflow 91 may be diphasic at theinlet 21. For ensuring that, when reaching thecompressor 2, the refrigerant of theflow 91 is in liquid form, or is in diphasic form with sufficient proportion of liquid refrigerant, the refrigerant apparatus comprises asubcooling heat exchanger 31 and asubcooling coolant branch 40 for cooling the refrigerant of theflow 91. - The
subcooling coolant branch 40 is distinct from the mainrefrigerant circuit 1, from themain coolant circuit 70 and from thebranch 20. Thesubcooling coolant branch 40 is connected to themain coolant circuit 70. Thebranch 40 is a passage for aflow 92 of coolant, originating from themain coolant flow 93 of themain coolant circuit 70. Theflow 92 is designated as "subcooling coolant flow". Thesubcooling coolant flow 92 is a flow of coolant, formed by a portion of themain coolant flow 93. - The
subcooling coolant branch 40 comprises aninlet 41, designated as "subcooling inlet", and anoutlet 42, designated as "subcooling outlet". - The
inlet 41 is connected to thecoolant passage 71 of themain coolant circuit 70, preferably at an exterior part of theevaporator 8 or within theevaporator 8. Preferably, theinlet 41 derives theflow 92 from theflow 93 of coolant which has not yet exchanged heat with theflow 90 of refrigerant within theevaporator 8 but which has already cooled all theclient devices 72 of thecircuit 70. Theflow 92 is introduced into thebranch 40 by theinlet 41. Preferably, theinlet 41 is connected to theinlet 75 at an exterior location of theevaporator 8. - The
outlet 42 is connected to thecoolant passage 71 of themain coolant circuit 70, preferably at an exterior part of theevaporator 8 or within theevaporator 8. Preferably, theoutlet 42 reintroduces the derivedcoolant flow 92 into thecoolant flow 93 themain coolant circuit 70, after saidcoolant flow 93 has exchanged heat with therefrigerant flow 90 in theevaporator 8 and before thecoolant flow 93 has cooled anyclient device 72 from thecircuit 70. Preferably, theoutlet 42 is connected to theoutlet 76 at an exterior location of theevaporator 8. - More generally, it is preferred that the
outlet 42 is connected to thecircuit 70 downstream relative to theinlet 41. In this case, since themain coolant flow 93 is circulated through thecircuit 70, for example by means of a non-shown circulator, connecting theinlet 41 upstream relative to theoutlet 42 enables that thesubcooling coolant flow 92 is also circulated, without further circulator, since the upstream pressure is higher than the downstream pressure in thepassage 71 of themain coolant circuit 70. - Alternatively, the
inlet 41 may be connected at theoutlet 76 and theoutlet 42 may be connected at theinlet 75. However, in this case, a circulator or any other circulation means may be implemented for imparting a circulation of theflow 92 through thebranch 40. - In any case, it is preferred that the
outlet 42 is connected at a part ofpassage 71 different from the part of thepassage 71 where theinlet 41 is connected. - The
subcooling heat exchanger 31 is configured for enabling or promoting an exchange of heat between theflows flow 91 is sub-cooled by exchange of heat with the coolant of theflow 92, within thesubcooling heat exchanger 31. Theflows flows heat exchanger 31, promoting heat exchange between theflows exchanger 31, theflow 91 is cooled by theflow 92, and theflow 92 is heated by theflow 91. - Since the refrigerant of the
lubrication flow 91 is cooled in theheat exchanger 31, the apparatus ensures that the refrigerant of thelubrication flow 91 is in liquid-state, or has a high proportion of liquid refrigerant, when entering thecompressor 2 at theoutlet 22. Even when the apparatus operates at low load, i.e. low flow rate of themain refrigerant flow 90, appropriate lubrication of thecompressor 2 is ensured. - The
branch 40 may be provided with a suitable valve, such as a throttle valve or solenoid valve, not shown in the figures, for adjusting or disabling the circulation of theflow 92 depending on the current load of the refrigeration apparatus. For example, the circulation of theflow 92 may be interrupted or reduced when the apparatus operates at high load for improving thermal efficiency of the refrigeration apparatus. For example, the circulation of theflow 92 may be enabled or increased when the apparatus operates a low load for improving lubrication of thecompressor 2. - As shown in
figures 1 and2 , thesubcooling heat exchanger 31 is positioned outside of theevaporator 8, preferably outside of the mainrefrigerant circuit 1 and preferably outside of themain coolant circuit 70. Thus, implementing theheat exchanger 31 in an existing refrigeration system is made easier, since the refrigeration system, including theevaporator 8, does not need to be modified significantly, but only requires appropriate connections with theheat exchanger 31. - As shown in
figure 2 , thesubcooling heat exchanger 31 comprises aheat exchange tank 32 and aheat exchange passage 33. - In the example of
figure 2 , thetank 32 belongs to thebranch 20, whereas theheat exchange passage 33 belongs to thebranch 40. In other non-shown embodiments not corresponding to the invention, this may be the opposite. More generally, one branch of the refrigeration apparatus, chosen among the lubrication refrigerant branch and the subcooling coolant branch, comprises thetank 32, while the other branch comprises theheat exchange passage 33. - In the case illustrated in
figure 2 , a quantity of refrigerant for lubrication from theflow 91 is received by thetank 32, allowing easy measuring of the proportion of liquid refrigerant received in thetank 32. The liquid refrigerant of theflow 91 received in thetank 32 may constitute a supply of liquid refrigerant that may be used at specific operation stages where little liquid refrigerant is available, for example during starting of the refrigeration apparatus. - The
flow 91 circulates through thetank 32, when circulating in thebranch 20 from theinlet 21 to theoutlet 22. For this purpose, thebranch 20 preferably comprises aninlet duct 24, connecting thelubrication inlet 21 to theheat exchange tank 32, for circulation of thelubrication flow 91 from thelubrication inlet 21 to theheat exchange tank 32. Theduct 24 crosses through a bottom wall of thetank 32 and comprises anopen inlet end 25, positioned within theheat exchange tank 32, for admission of thelubrication flow 91 into theheat exchange tank 32 at the vicinity of a top wall of thetank 32. Thebranch 20 also preferably comprises anoutlet duct 26, connecting theheat exchange tank 32 to thelubrication outlet 22, for circulation of thelubrication flow 91 from theheat exchange tank 32 to thelubrication outlet 22. Theduct 26 crosses through the bottom wall of thetank 32 and comprises anopen outlet end 27, positioned within theheat exchange tank 32 at the vicinity of the bottom wall of thetank 32, or at the bottom wall of thetank 32. Thus, theoutlet end 27 is at a lower height than theinlet end 25. - During operation, the refrigerant of the
flow 91 temporarily rests in thetank 32 where heat is exchanged with thecoolant flow 92 received in thepassage 33. In thetank 32, the refrigerant of theflow 91 is either fully liquid, in particular during high load operation of the apparatus, or diphasic, in particular during low load operation of the apparatus. When diphasic, the liquid refrigerant sits at the bottom of thetank 32 while the gaseous refrigerant is located at the top. Thus, since theinlet end 25 is located above theoutlet end 27, agitation of the refrigerant of thetank 32 is reduced, avoiding reintroduction of gaseous refrigerant into the liquid refrigerant of thetank 32 if the admitted refrigerant is partially gaseous. In addition, with theoutlet end 27 being located at the vicinity of the bottom wall of the tank, the risk of admitting gas bubbles into theoutlet end 27 is reduced, even if alevel 94 of liquid refrigerant in thetank 32 is low. - The
heat exchange tank 32 comprises at least one liquid level sensor, preferably twoliquid level sensors heat exchange tank 32, at a respective height. Thesensor 35 is configured to detect the presence of liquid refrigerant in the tank at the same height than, or slightly above, theoutlet end 27. Thus, thesensor 35 may be used for detecting when the amount of available liquid refrigerant in thetank 32 is too low for correct lubrication of thecompressor 2 in steady-state of the refrigerating apparatus, for example during low load operation of the refrigerating apparatus. Thesensor 36 is configured to detect the presence of liquid refrigerant in thetank 32 at a higher height than thesensor 35, between the height of theend 25 and the height of theend 27. Thesensor 36 may be used for detecting when the amount of available liquid refrigerant in thetank 32 is above or below an acceptable level for starting the refrigerating apparatus, which may require that a high amount of liquid refrigerant is available in thetank 32 for lubrication of thecompressor 2. In the case illustrated infigure 2 , thelevel 94 of liquid refrigerant received within thetank 32 is at a height comprised betweensensors only sensor 35 detects the presence of liquid refrigerant. - If one of the
sensors 35 and/or 36 detect that liquid refrigerant is not available at their respective height, operating of thecompressor 2 may be interrupted to avoid the risk of damage to thecompressor 2. - In a non-shown embodiment, the
tank 32 comprises a number of liquid level sensors different than two, each detecting the presence of liquid refrigerant in thetank 32 at a respective height. - The
heat exchange passage 33 is positioned within theheat exchange tank 32, so as to be surrounded by the refrigerant of theflow 91. Thepassage 33 is configured so that thecoolant flow 92 circulating through thebranch 40 circulates through thepassage 33, when circulating from theinlet 41 to theoutlet 42. Preferably, as shown infigure 2 , thepassage 33 is a coil duct, promoting heat exchange. The coil duct is preferably made of a material with high heat conductivity such as copper or the like. The coil duct has the advantage that it does not induce too much pressure drop for theflow 92 flowing through. However, instead of a coil duct, any other suitable shape may be implemented for thepassage 33, promoting heat exchange without inducing too much pressure drop of theflow 92 and too much agitation for theflow 91 sitting in thetank 32. - The
heat exchange passage 33 comprises acoolant inlet 43, connected to thesubcooling inlet 41 by an inlet duct of thebranch 40. Theheat exchange passage 33 comprises acoolant outlet 44, connected to thesubcooling outlet 42 by an outlet duct of thebranch 40. Theinlet 43 and theoutlet 44 are preferably positioned at a peripheral wall of theheat exchange tank 32. The peripheral wall is preferably vertical, and connects the top wall to the bottom wall of thetank 32. - For better thermal efficiency, the
inlet 43 is preferably at a different height, such as a lower height, than theoutlet 44, as shown infigure 2 . The coil duct of thepassage 33, connecting theinlet 43 to theoutlet 44, is preferably vertical overall. As shown infigure 2 , theinlet 43 is preferably connected to thetank 31 at the bottom of thetank 31, or at least at the vicinity of theoutlet 27, so that theflow 92 entering theheat exchange passage 33 is close to theoutlet 27. In this case, as shown infigure 2 , theheat exchanger 32 is preferably a counterflow heat exchanger. - Preferably, the
heat exchange tank 32, and in particular theopen outlet end 27, is positioned at a higher height than thecompressor 2, so that the compressor is fed with thelubrication refrigerant flow 91 under the effect of gravity. Thus, the need for a circulator for circulating theflow 91 is reduced. - Preferably, as depicted in
figure 2 , theevaporator 8 is a flooded heat exchanger, such as a flooded tube heat exchanger. In this case, therefrigerant passage 61 comprises a tank, designated as "evaporator tank", receiving the refrigerant from theflow 90 of the mainrefrigerant circuit 1. Preferably, thetank 61 is of generally cylindrical shape, as this is the case infigure 2 . Theinlet 18 is preferably connected at the bottom of thetank 61 for admission of theflow 90 into thetank 61 by the bottom thereof. Theoutlet 19 is preferably connected at the top of thetank 61 for discharging of theflow 90 into thetank 61 by the top thereof. In operation of the refrigeration apparatus, the refrigerant of theflow 90 received within thetank 61 is advantageously in diphasic form, so that the liquid part of the received refrigerant sits at the bottom of thetank 61, whereas the gaseous part of the received refrigerant evaporates towards the top of thetank 61, when receiving heat from thecoolant flow 93 circulating through thecoolant passage 71. - Preferably, the
coolant passage 71 comprises a heat exchange duct, as depicted infigure 2 , crossing through theevaporator tank 61 so as to be surrounded by the refrigerant received in thetank 61. Thecoolant flow 93 flows through theheat exchange duct 71 so that heat is exchanged between saidcoolant flow 93 and therefrigerant flow 90 received within thetank 61. For this purpose, one end of theexchange duct 71 is connected to theinlet 75 whereas the other end of theexchange duct 71 is connected to theoutlet 76. - The
heat exchange duct 71 is preferably made of a heat conductive material, such as copper or the like, so as to promote exchange of heat between theflows - The
heat exchange duct 71 may be in the form of a coil duct. - Alternatively, the
coolant passage 71 may comprise several heat exchange ducts, each connected to theinlet tank 61 so as to be surrounded with the refrigerant of themain circuit 1 received within thetank 61, and each circulated by a portion of theflow 93. - The
valves 23, when both closed, may also be used for temporarily storing refrigerant within thebranch 20, in particular within thetank 32 of theheat exchanger 31, especially for periods of time when the refrigeration apparatus is stopped, allowing that liquid-state refrigerant is available in thetank 31 before re-starting. For this purpose, onevalve 23 is positioned upstream from thetank 32 and theother valve 23 is positioned downstream of fromtank 32. - Alternatively, at least one of the subcooling inlet and the subcooling outlet is positioned within the
evaporator tank 61, preferably the subcooling inlet. Thus, thesubcooling coolant flow 92 is derived from the part of thecoolant passage 71 extending within theevaporator tank 61, namely the heat exchange duct. Thus, the derivedsubcooling coolant flow 92 is at a lower temperature, which may be useful at starting of the refrigeration apparatus. - Alternatively, two subcooling inlets may be provided for deriving the
flow 92, one connected to theinlet 75 and the other connected to theheat exchange duct 71. Thebranch 40 may be provided with appropriate valves for selecting by means of which of the subcooling inlets theflow 92 is derived, depending on the operation stage of the refrigeration apparatus. - Alternatively, where the evaporator is a flooded heat exchanger, the refrigerant passage of the evaporator constitutes the heat exchange duct whereas the coolant passage of the evaporator constitutes the evaporator tank. Each feature disclosed for an embodiment disclosed above may be implemented in any other embodiment disclosed above, as long as technically feasible.
Claims (14)
- A refrigeration apparatus, comprising a main refrigerant circuit (1), including:- a compressor (2), including a compressor inlet (12) and a compressor outlet (13),- a condenser (4), including a condenser inlet (14), connected to the compressor outlet (13), and a condenser outlet (15),- an expansion valve (6), including a valve inlet (16), connected to the condenser outlet (15) and a valve outlet (17), and- a refrigerant passage (61), extending at least partially within an evaporator (8) of the refrigeration apparatus, the refrigerant passage (61) including a refrigerant passage inlet (18), connected to the valve outlet (17), and a refrigerant passage outlet (19), connected to the compressor inlet (12), the refrigeration apparatus also including a coolant passage (71) extending at least partially within the evaporator (8) and including a coolant passage inlet (75) and a coolant passage outlet (76),wherein the main refrigerant circuit (1) is configured for a loop circulation of a main refrigerant flow (90) of a refrigerant, successively through the compressor (2), the condenser (4), the expansion valve (6), and the refrigerant passage (61),wherein the evaporator (8) is configured for enabling an exchange of heat between the main refrigerant flow (90) circulating through the refrigerant passage (61) and a main coolant flow (93) of a coolant circulating through the coolant passage (71),wherein the refrigeration apparatus further comprises a lubrication branch (20), comprising:- a lubrication inlet (21), connected to a supply part (4, 16) of the main circuit (1), the supply part (4, 16) consisting in the condenser (4), the valve inlet (16), and any part of the main circuit (1) between the condenser outlet (15) and the valve inlet (16), the lubrication inlet (21) being configured to derive a lubrication refrigerant flow (91) from the main refrigerant flow (90) circulating through the supply part (4, 16); and- a lubrication outlet (22), connected to the compressor (2) so as to feed the compressor (2) with the lubrication refrigerant flow (91), for lubrication of said compressor (2) with the refrigerant of the lubrication refrigerant flow (91),wherein the refrigeration apparatus further comprises:- a subcooling branch (40), comprising:∘ a subcooling inlet (41), connected to the coolant passage (71), so as to derive a subcooling coolant flow (92) from the main coolant flow (93), and∘ a subcooling outlet (42), connected to the coolant passage (71), for reintroducing the subcooling coolant flow (92) into the main coolant flow (93); and- a subcooling heat exchanger (31), being configured for enabling an exchange of heat between the subcooling coolant flow (92) circulating through the subcooling branch (40) and the lubrication refrigerant flow (91) circulating through the lubrication branch (20), so that the lubrication refrigerant flow (91) may be cooled by the subcooling coolant flow (92) within the subcooling heat exchanger (31),wherein the subcooling heat exchanger (31) comprises:- a heat exchange tank (32), belonging to the lubrication branch (20) and being configured so that the lubrication refrigerant flow (91) circulates through the heat exchange tank (32), and- a heat exchange passage (33), belonging to the subcooling branch (40), being positioned within the heat exchange tank (32) and being configured so that the subcooling coolant flow (92) circulates through the heat exchange passage (33),characterized in that the heat exchange tank (32) comprises at least one liquid level sensor (35, 36), detecting the presence of liquid refrigerant at a respective height within the heat exchange tank (32).
- The refrigeration apparatus according to claim 1, wherein:- the subcooling inlet (41) is connected to a coolant passage inlet (75) of the coolant passage (71), so as to derive the subcooling coolant flow (92) from the main coolant flow (93) circulating through the coolant passage inlet (75), and- the subcooling outlet (42) is connected to a coolant passage outlet (76) of the coolant passage (71), for reintroducing the subcooling coolant flow (92) into the main coolant flow (93) circulating through the coolant passage outlet (76).
- The refrigeration apparatus according to any one of the preceding claims, wherein:- the refrigerant passage (61) comprises an evaporator tank of the evaporator (8), the evaporator tank being connected to the refrigerant passage inlet (18), for admitting the main refrigerant flow (90) into the evaporator tank, and to the refrigerant passage outlet (19), for discharging the main refrigerant flow (90) from the evaporator tank ; and- the coolant passage (71) comprises at least one heat exchange duct of the evaporator (8), the heat exchange duct extending within the evaporator tank so as to be surrounded by the main refrigerant flow received within the evaporator tank, the heat exchange duct being connected to the coolant passage inlet (75), for admitting the main coolant flow (93) into the heat exchange duct, and to the coolant passage outlet (76), for discharging of the main coolant flow (93) from the heat exchange duct.
- The refrigeration apparatus according to any one of the preceding claims, wherein the subcooling heat exchanger (31) is positioned outside of the evaporator (8).
- The refrigeration apparatus according to any one of the preceding claims, wherein the lubrication branch (20) comprises:- an inlet duct (24), connecting the lubrication inlet (21) to the heat exchange tank (32), for circulation of the lubrication refrigerant flow (91) from the lubrication inlet (21) to the heat exchange tank (32), and comprising an open inlet end (25) positioned within the heat exchange tank (32) for admission of the lubrication refrigerant flow (91) into the heat exchange tank (32); and- an outlet duct (26), connecting the heat exchange tank (32) to the lubrication outlet (22), for circulation of the lubrication refrigerant flow (91) from the heat exchange tank (32) to the lubrication outlet (22), and comprising an open outlet end (27) positioned within the heat exchange tank (32), at a lower height than the open inlet end (25).
- The refrigeration apparatus according to claim 5, wherein said at least one liquid level sensor (35, 36) comprises a first sensor (35), configured to detect the presence of liquid refrigerant in the heat exchange tank (32) at the same height than, or slightly above, the open outlet end (27).
- The refrigeration apparatus according to claim 6, wherein said at least one liquid level sensor (35, 36) comprises a second sensor (36), configured to detect the presence of liquid refrigerant (32) at a higher height than the first sensor (35), between the height of the open inlet end (25) and the height of the open outlet end (27).
- The refrigeration apparatus according to any one of the preceding claims, wherein the heat exchange tank (32) is positioned at a higher height than the lubrication outlet (22), so that the compressor (2) is fed with the lubrication refrigerant flow (91) by gravity.
- The refrigeration apparatus according to any one of the preceding claims, wherein the heat exchange passage (33) is a coil duct.
- The refrigeration apparatus according to any one of the preceding claims, wherein, for being connected to the supply part (4, 16), the lubrication inlet (21) is connected to a bottom part (29) of the condenser (4).
- The refrigeration apparatus according to any one of the preceding claims, wherein the compressor (2) is a positive displacement-type compressor.
- The refrigeration apparatus according to any one of the preceding claims, wherein:- the compressor (2) is a screw compressor comprising two meshing screw rotors and bearings, the screw-rotors being supported by the bearings, and- the lubrication outlet (22) is connected to the compressor (2) so as to feed the bearings and the screw rotors with the lubrication refrigerant flow (91), for lubrication of said bearings and screw rotors.
- A refrigeration system, comprising a refrigeration apparatus according to any one of the preceding claims, and comprising a main coolant circuit (70), including the coolant passage (71) and at least one client device (72) to be cooled by the main coolant flow (93), the main coolant circuit (70) being configured for loop circulation of the main coolant flow (93) through the main coolant circuit (70), successively through the coolant passage (71) and said at least one client device (72), the coolant of the main coolant flow (93) preferably comprising water.
- A use of the refrigeration apparatus according to any one of claims 1 to 12, or of the refrigeration system according to claim 13, the use including:- closed loop circulation of the main refrigerant flow (90) successively through the compressor inlet (12), the compressor (2), the compressor outlet (13), the condenser inlet (14), the condenser (4), the condenser outlet (15), the valve inlet (16), the expansion valve (6), the valve outlet (17), the refrigerant passage inlet (18), the refrigerant passage (61), and the refrigerant passage outlet (19);- derivation of the lubrication refrigerant flow (91) from the main refrigerant flow (90) circulating through the supply part (4, 16), by the lubrication inlet (21),- circulation of the lubrication refrigerant flow (91) through the lubrication branch (20), successively through the lubrication inlet (21), the subcooling heat exchanger (31) and the lubrication outlet (22),- derivation of the subcooling coolant flow (92) from the main coolant flow (93) circulating through the coolant passage (71), by the subcooling inlet (41),- circulation of the subcooling coolant flow (92) through the subcooling branch (40), successively through the subcooling inlet (41), the subcooling heat exchanger (31) and the subcooling outlet (42),- exchange of heat between the subcooling coolant flow (92) and the lubrication refrigerant flow (91) in the subcooling heat exchanger (31), so that the lubrication refrigerant flow (91) is cooled by the subcooling coolant flow (92),- feeding of the compressor (2), by the lubrication outlet (22), with the lubrication refrigerant flow (91) that was cooled by the subcooling coolant flow (92) in the subcooling heat exchanger (31), for lubrication of the compressor (2), and- reintroduction, by the subcooling outlet (42), of the subcooling coolant flow (92) that has cooled the lubrication refrigerant flow (91) in the subcooling heat exchanger (31), into the main coolant flow (93) circulating through the coolant passage (71).
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP19175785.5A EP3742069B1 (en) | 2019-05-21 | 2019-05-21 | Refrigeration apparatus and use thereof |
US16/874,645 US20200370803A1 (en) | 2019-05-21 | 2020-05-14 | Refrigeration apparatus and use thereof |
CN202010423682.2A CN111981716A (en) | 2019-05-21 | 2020-05-19 | Refrigeration equipment and use method thereof |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
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EP19175785.5A EP3742069B1 (en) | 2019-05-21 | 2019-05-21 | Refrigeration apparatus and use thereof |
Publications (2)
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EP3742069A1 EP3742069A1 (en) | 2020-11-25 |
EP3742069B1 true EP3742069B1 (en) | 2024-03-20 |
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EP19175785.5A Active EP3742069B1 (en) | 2019-05-21 | 2019-05-21 | Refrigeration apparatus and use thereof |
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US (1) | US20200370803A1 (en) |
EP (1) | EP3742069B1 (en) |
CN (1) | CN111981716A (en) |
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WO2024168030A1 (en) * | 2023-02-07 | 2024-08-15 | Tyco Fire & Security Gmbh | Bearing system for hvac&r system |
WO2024168044A1 (en) * | 2023-02-07 | 2024-08-15 | Tyco Fire & Security Gmbh | Fluid supply system for bearings of hvac&r system |
WO2024168042A1 (en) * | 2023-02-07 | 2024-08-15 | Tyco Fire & Security Gmbh | Pressure accumulator for hvac&r system |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5884498A (en) * | 1996-10-25 | 1999-03-23 | Mitsubishi Heavy Industries, Ltd. | Turborefrigerator |
Family Cites Families (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH04103573U (en) * | 1991-02-08 | 1992-09-07 | カルソニツク株式会社 | Oil separator of refrigerant recovery equipment |
JPH10220885A (en) * | 1997-01-31 | 1998-08-21 | Mitsubishi Heavy Ind Ltd | Refrigerating machine |
US6176092B1 (en) * | 1998-10-09 | 2001-01-23 | American Standard Inc. | Oil-free liquid chiller |
JP4330369B2 (en) | 2002-09-17 | 2009-09-16 | 株式会社神戸製鋼所 | Screw refrigeration equipment |
DE102004060596A1 (en) * | 2004-12-02 | 2006-06-22 | Bitzer Kühlmaschinenbau Gmbh | screw compressors |
US20060225459A1 (en) * | 2005-04-08 | 2006-10-12 | Visteon Global Technologies, Inc. | Accumulator for an air conditioning system |
JP4787070B2 (en) * | 2006-05-30 | 2011-10-05 | サンデン株式会社 | Refrigeration cycle |
DK2198214T3 (en) * | 2007-09-28 | 2011-06-27 | Carrier Corp | Refrigerant circuits and method for handling oil therein |
KR101668363B1 (en) * | 2015-07-15 | 2016-10-21 | 한국에너지기술연구원 | Energy system |
CN205156435U (en) * | 2015-11-19 | 2016-04-13 | 珠海格力电器股份有限公司 | Oil cooling system, refrigerating system and refrigerating unit |
JP6672056B2 (en) * | 2016-04-22 | 2020-03-25 | 三菱重工サーマルシステムズ株式会社 | Turbo compressor, turbo refrigeration device provided with the same |
CN207035565U (en) * | 2017-05-19 | 2018-02-23 | 江苏必领能源科技有限公司 | Superhigh-temperature heat pump device with thermal source recovery |
-
2019
- 2019-05-21 EP EP19175785.5A patent/EP3742069B1/en active Active
-
2020
- 2020-05-14 US US16/874,645 patent/US20200370803A1/en not_active Abandoned
- 2020-05-19 CN CN202010423682.2A patent/CN111981716A/en active Pending
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5884498A (en) * | 1996-10-25 | 1999-03-23 | Mitsubishi Heavy Industries, Ltd. | Turborefrigerator |
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EP3742069A1 (en) | 2020-11-25 |
US20200370803A1 (en) | 2020-11-26 |
CN111981716A (en) | 2020-11-24 |
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