EP3732377B1 - Energy recovery circuit from a thermal source and related energy recovery method - Google Patents
Energy recovery circuit from a thermal source and related energy recovery method Download PDFInfo
- Publication number
- EP3732377B1 EP3732377B1 EP18839731.9A EP18839731A EP3732377B1 EP 3732377 B1 EP3732377 B1 EP 3732377B1 EP 18839731 A EP18839731 A EP 18839731A EP 3732377 B1 EP3732377 B1 EP 3732377B1
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- EP
- European Patent Office
- Prior art keywords
- operating fluid
- expander
- heat exchanger
- stator
- inlet
- Prior art date
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- 238000011084 recovery Methods 0.000 title claims description 25
- 238000000034 method Methods 0.000 title claims description 12
- 239000012530 fluid Substances 0.000 claims description 60
- 239000007788 liquid Substances 0.000 claims description 18
- 239000000314 lubricant Substances 0.000 claims description 5
- 229920000728 polyester Polymers 0.000 claims description 2
- 239000012809 cooling fluid Substances 0.000 claims 2
- 238000011144 upstream manufacturing Methods 0.000 claims 2
- 238000002347 injection Methods 0.000 description 6
- 239000007924 injection Substances 0.000 description 6
- 230000009467 reduction Effects 0.000 description 5
- 238000005516 engineering process Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 239000010687 lubricating oil Substances 0.000 description 2
- 238000005461 lubrication Methods 0.000 description 2
- 239000012071 phase Substances 0.000 description 2
- 238000004378 air conditioning Methods 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 239000010725 compressor oil Substances 0.000 description 1
- 230000001143 conditioned effect Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 239000002826 coolant Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 230000037361 pathway Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 239000002918 waste heat Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
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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
- F04C29/0007—Injection of a fluid in the working chamber for sealing, cooling and lubricating
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01C—ROTARY-PISTON OR OSCILLATING-PISTON MACHINES OR ENGINES
- F01C1/00—Rotary-piston machines or engines
- F01C1/30—Rotary-piston machines or engines having the characteristics covered by two or more groups F01C1/02, F01C1/08, F01C1/22, F01C1/24 or having the characteristics covered by one of these groups together with some other type of movement between co-operating members
- F01C1/34—Rotary-piston machines or engines having the characteristics covered by two or more groups F01C1/02, F01C1/08, F01C1/22, F01C1/24 or having the characteristics covered by one of these groups together with some other type of movement between co-operating members having the movement defined in group F01C1/08 or F01C1/22 and relative reciprocation between the co-operating members
- F01C1/344—Rotary-piston machines or engines having the characteristics covered by two or more groups F01C1/02, F01C1/08, F01C1/22, F01C1/24 or having the characteristics covered by one of these groups together with some other type of movement between co-operating members having the movement defined in group F01C1/08 or F01C1/22 and relative reciprocation between the co-operating members with vanes reciprocating with respect to the inner member
- F01C1/3441—Rotary-piston machines or engines having the characteristics covered by two or more groups F01C1/02, F01C1/08, F01C1/22, F01C1/24 or having the characteristics covered by one of these groups together with some other type of movement between co-operating members having the movement defined in group F01C1/08 or F01C1/22 and relative reciprocation between the co-operating members with vanes reciprocating with respect to the inner member the inner and outer member being in contact along one line or continuous surface substantially parallel to the axis of rotation
- F01C1/3442—Rotary-piston machines or engines having the characteristics covered by two or more groups F01C1/02, F01C1/08, F01C1/22, F01C1/24 or having the characteristics covered by one of these groups together with some other type of movement between co-operating members having the movement defined in group F01C1/08 or F01C1/22 and relative reciprocation between the co-operating members with vanes reciprocating with respect to the inner member the inner and outer member being in contact along one line or continuous surface substantially parallel to the axis of rotation the surfaces of the inner and outer member, forming the working space, being surfaces of revolution
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01C—ROTARY-PISTON OR OSCILLATING-PISTON MACHINES OR ENGINES
- F01C21/00—Component parts, details or accessories not provided for in groups F01C1/00 - F01C20/00
- F01C21/06—Heating; Cooling; Heat insulation
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
- F01K25/00—Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for
- F01K25/08—Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for using special vapours
-
- 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
- F04C23/00—Combinations of two or more pumps, each being of rotary-piston or oscillating-piston type, specially adapted for elastic fluids; Pumping installations specially adapted for elastic fluids; Multi-stage pumps specially adapted for elastic fluids
- F04C23/02—Pumps characterised by combination with, or adaptation to, specific driving engines or motors
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B31/00—Compressor arrangements
- F25B31/006—Cooling of compressor or motor
Definitions
- the present invention relates to an energy recovery circuit from a thermal source using a vane expander and an energy recovery method achievable by means of such circuit.
- Vane expanders comprising a stator provided with an inlet port and an outlet port, and a rotor eccentrically housed in the stator, internally tangent to a side wall of the stator and provided with a plurality of vanes sliding radially relative to the rotor and cooperating in a sealed manner with the stator.
- vane volumetric expanders in energy recovery systems (e.g. based on a Rankine cycle using a high molecular weight organic operating fluid, known as ORC) from waste heat sources in the industrial, automotive or civil sectors, etc.
- ORC high molecular weight organic operating fluid
- Volumetric vane expanders offer important advantages in terms of efficiency and power produced compared to other available technologies, especially when the enthalpic content of thermal sources is very low, for example when the temperature of the thermal source is between 80° and 120 °C.
- vane volumetric expanders is conditioned by the fluid dynamic losses occurring during the expansion phase due to the unavoidable clearance between the vanes, the rotor and the stator.
- Fluid dynamic losses due to leaks are also the cause of a deviation of the real pressure/volume curve from the (ideal) adiabatic curve.
- This rolling also results in a reduction of temperature and pressure inside the expander, which also results in an inefficient and incomplete filling phase and a less efficient subsequent expansion, further away from the ideal adiabatic curve. This penalises the work indicated and the volumetric yield.
- the present invention also relates to an energy recovery method according to claim 8.
- the fluid may be preheated prior to injection into the expander, so as to avoid lowering the temperature in the compartment.
- this can be achieved by means of the residual heat of the thermal source or by the hot fluid in output from the expander; in a recovery ORC circuit, the fluid can be drawn downstream of the recovery heat exchanger placed between the pump and the evaporator where it is heated by the hot fluid in output from the expander.
- the flow rate of liquid injected into the expander is less than 50 of the total flow rate, and preferably less than 3%. This optimises the seal without causing substantial and unwanted temperature reductions.
- the stator 2 comprises a substantially hollow cylindrical stator barrel 4 and a pair of axial closing heads 5, of which only one is visible in figure 1 .
- the stator barrel 4 has an inner cylindrical surface 6 of axis A.
- the chamber 14 communicates with an inlet port 16 and an outlet port 17 for an operating fluid made in the stator 2.
- the inlet port 16 is placed at one end of the chamber 9 near the tangent zone between the body 7 of the rotor 3 and the stator barrel 4, the outlet port extends from the area of maximum width of the chamber 14 to an opposite end of said chamber, near the tangent zone.
- This portion 18, indicated by a lined section in figure 1 is angularly distant from each of the inlet 16 and outlet ports 17 by an angle equal to the angular width of a compartment 15, and therefore extends along an angle ⁇ equal to the angular distance between the inlet port 16 and the outlet port 17 minus twice the angular width of a compartment 15.
- the rotor 3 is shown by a solid line in a first position where a first compartment 15 of the expansion zone begins to be isolated from the inlet port 16 by a vane 9.
- the vanes 9 are also illustrated (lined) in a second position in which a last compartment 15 of the expansion zone is in an incipient outlet position, i.e. a position in which a vane 9 still isolates such compartment 15 from the outlet port 17 but wherein a minimum rotation of the rotor 3 would bring it into communication therewith.
- the portion 18 is always isolated from both the inlet port 16 and the outlet port 17, at any angular position of the rotor 3.
- the fluid injected into such portion does not find low resistance pathways to the ports 16, 17 and tends to infiltrate the axial and radial clearance between the vanes 9, the body 7 of the rotor 3 and the stator 2, significantly improving the seal.
- the injection of fluid takes place through a calibrated radial hole 20 made in the stator barrel 4, and provided with a threaded fitting 21 for connection to a supply pipe.
- the fitting 21 is arranged in an initial area of the portion 18.
- the injection takes place through a pair of axial holes 22 arranged one after the other in a circumferential direction and made in one of the heads 5.
- the holes 22 are shifted towards the rotor relative to a longitudinal centreline of the chamber 14 so as to lubricate the interlocking zone of vanes 9 in the seats 10.
- FIG 3 illustrates a simple (non-recovery) ORC-type energy recovery circuit 25.
- the thermal source the residual energy of which is to be recovered is the lubricating oil of a compressor C.
- the circuit 25 uses an organic operating fluid, conveniently consisting of a hydrofluorocarbon (HFC) or a hydrofluoroolefin (HFO) to which a compatible lubricant is added, e.g. a polyester-based oil (POE), e.g. in a 5% by mass percentage.
- HFC hydrofluorocarbon
- HFO hydrofluoroolefin
- POE polyester-based oil
- the ORC circuit comprises:
- the operating fluid in the liquid state is drawn from the high pressure branch of the circuit 25, i.e. downstream of the circulation pump, and is injected into the expander 1 as described above.
- a duct 26 connects a node of the circuit downstream of the pump P to the fitting 21 or holes 22.
- this is preheated, e.g., by a third heat exchanger PXH in which it exchanges heat with the vapour at the outlet of the expander 1.
- the operating fluid in the liquid state may be preheated by the residual heat of the thermal source, in this case the compressor oil, rather than by the operating fluid in output from the expander.
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Engine Equipment That Uses Special Cycles (AREA)
Description
- This patent application claims priority from
Italian patent application no. 102017000151139 filed on 29/12/2017 - The present invention relates to an energy recovery circuit from a thermal source using a vane expander and an energy recovery method achievable by means of such circuit.
- Vane expanders are known comprising a stator provided with an inlet port and an outlet port, and a rotor eccentrically housed in the stator, internally tangent to a side wall of the stator and provided with a plurality of vanes sliding radially relative to the rotor and cooperating in a sealed manner with the stator.
- The stator and rotor delimit between them a circumferential chamber with width varying from zero in the tangent area to a maximum value near one end of the outlet port; the vanes divide the chamber into a plurality of compartments with volume varying with the rotation of the rotor, each of which has a minimum volume at the inlet port and a maximum volume near the beginning of the outlet port. The operating fluid entering a compartment communicating with the inlet port is thus expanded and discharged to the outlet port; the expansion makes mechanical energy available to an outlet shaft rotationally connected to the rotor.
- It is known to use vane volumetric expanders in energy recovery systems (e.g. based on a Rankine cycle using a high molecular weight organic operating fluid, known as ORC) from waste heat sources in the industrial, automotive or civil sectors, etc.
- Volumetric vane expanders offer important advantages in terms of efficiency and power produced compared to other available technologies, especially when the enthalpic content of thermal sources is very low, for example when the temperature of the thermal source is between 80° and 120 °C.
- Other advantages of vane volumetric expanders compared to other technologies available for energy recovery systems are the low-rotation speed operating capacity, automatic starting without the need to be driven by an electric motor, reduced noise emission, low vibration, and a structure based on simple components and absence of flow control valves.
- Despite the advantages described above, the performance of vane volumetric expanders is conditioned by the fluid dynamic losses occurring during the expansion phase due to the unavoidable clearance between the vanes, the rotor and the stator.
- In addition, in small ORC systems, to avoid significant system design complication, direct lubrication systems are not used but a small amount of lubricant mixed with the operating fluid is used.
- The fraction of lubricant that can be used to ensure the correct lubrication of the expander without causing an excessive reduction in the efficiency of heat exchange in the heat exchangers is insufficient to properly fill the geometric clearance and thus to ensure a good seal between the compartments of the expander: this generates a clear reduction in pressure during the filling of the compartments before closing the inlet port.
- Fluid dynamic losses due to leaks are also the cause of a deviation of the real pressure/volume curve from the (ideal) adiabatic curve.
- This condition is inherent to vane technology and cannot be improved merely with correct geometric design.
- Considering a typical ORC thermodynamic cycle associated with a recovery system equipped with a vane expander, there is a difference between the flow rate supplied by the pump and the flow rate of operating fluid that actually produces a useful effect during expansion: in fact, in the absence of a perfect seal between the compartments of the expander, a part of the flow rate supplied by the pump does not participate in the expansion process and leaks between the compartments in the direction of the lowest pressure. This phenomenon can be assimilated to expansion through a nozzle (therefore without useful production).
- The higher the leaks in the expander, the greater the difference between the flow rate that actually participates in the expansion and the total flow rate supplied by the pump. This difference can be up to 20%.
- This rolling also results in a reduction of temperature and pressure inside the expander, which also results in an inefficient and incomplete filling phase and a less efficient subsequent expansion, further away from the ideal adiabatic curve. This penalises the work indicated and the volumetric yield.
-
US 2008/0141705 A1 discloses an air conditioning system having an expander for recuperation of mechanical energy from the expansion of the operating fluid. The expander has an auxiliary inlet for the injection of fluid from downstream the condenser into the expansion chamber. - The purpose of the present invention is the construction of an energy recovery circuit comprising a vane expander, which overcomes the drawbacks described above.
- The above purpose is achieved by an energy recovery circuit according to
claim 1. - The present invention also relates to an energy recovery method according to claim 8.
- Thanks to the injection of operating fluid in the liquid state, the sealing of the compartments is improved and consequently the work and the volumetric efficiency of the expander are optimized.
- According to a preferred embodiment of the invention, the fluid may be preheated prior to injection into the expander, so as to avoid lowering the temperature in the compartment. In a non-recovery ORC circuit, this can be achieved by means of the residual heat of the thermal source or by the hot fluid in output from the expander; in a recovery ORC circuit, the fluid can be drawn downstream of the recovery heat exchanger placed between the pump and the evaporator where it is heated by the hot fluid in output from the expander.
- Conveniently, the flow rate of liquid injected into the expander is less than 50 of the total flow rate, and preferably less than 3%. This optimises the seal without causing substantial and unwanted temperature reductions.
- For a better understanding of the present invention some preferred embodiments are described below with reference to the appended drawings, wherein:
-
figure 1 is a cross-section of a first embodiment of a vane expander that can be used in an energy recovery circuit according to the invention; -
figure 2 is a cross-section of a second embodiment of a vane expander that can be used in an energy recovery circuit according to the invention; -
figure 3 is a diagram of a first embodiment of an energy recovery circuit according to the present invention; and -
figure 4 is a diagram of a second embodiment of an energy recovery circuit according to the present invention. - With reference to
figure 1 ,reference numeral 1 globally denotes a vane expander comprising astator 2 and arotor 3 eccentrically housed rotationally free inside thestator 2 and provided with at least one output shaft not shown. - The
stator 2 comprises a substantially hollowcylindrical stator barrel 4 and a pair ofaxial closing heads 5, of which only one is visible infigure 1 . Thestator barrel 4 has an innercylindrical surface 6 of axis A. - The
rotor 3 comprises a cylindrical body 7 of axis B tangent to theinner surface 6 of thestator barrel 4 and a plurality ofvanes 9 sliding in respectiveradial seats 10 of the body 7. Thevanes 9 are pushed in a centrifugal direction, e.g. by means of springs or ejection and motion control rings, fluid pressure or a combination thereof, to cooperate in a sealed manner with theinner surface 6 of thestator barrel 4. - The
stator barrel 4 and the body 7 of therotor 3 delimit between them acircumferential chamber 14 of radial width varying from a substantially null value at the tangent generatrix T to a maximum value at a diametrically opposite generatrix S. Thechamber 14 is divided by thevanes 9 into a plurality ofcompartments 15. - The
chamber 14 communicates with aninlet port 16 and anoutlet port 17 for an operating fluid made in thestator 2. In particular, theinlet port 16 is placed at one end of thechamber 9 near the tangent zone between the body 7 of therotor 3 and thestator barrel 4, the outlet port extends from the area of maximum width of thechamber 14 to an opposite end of said chamber, near the tangent zone. - The
chamber 14 therefore has an expansion zone (with increasing radial width) and an outlet zone (with decreasing radial width); depending on the number ofvanes 9, in the example shown seven, a certain number ofcompartments 15 are located in the expansion zone and a certain number of compartments are located in the outlet zone. - According to the present invention, the expander comprises at least one supplementary inlet for a supplementary introduction of operating fluid in the liquid state into an expansion portion 18 of the chamber isolated from the inlet port and the outlet port.
- This portion 18, indicated by a lined section in
figure 1 , is angularly distant from each of theinlet 16 andoutlet ports 17 by an angle equal to the angular width of acompartment 15, and therefore extends along an angle α equal to the angular distance between theinlet port 16 and theoutlet port 17 minus twice the angular width of acompartment 15. - In
figure 1 , therotor 3 is shown by a solid line in a first position where afirst compartment 15 of the expansion zone begins to be isolated from theinlet port 16 by avane 9. Thevanes 9 are also illustrated (lined) in a second position in which alast compartment 15 of the expansion zone is in an incipient outlet position, i.e. a position in which avane 9 still isolatessuch compartment 15 from theoutlet port 17 but wherein a minimum rotation of therotor 3 would bring it into communication therewith. - From this representation it can be seen clearly that the portion 18 is always isolated from both the
inlet port 16 and theoutlet port 17, at any angular position of therotor 3. Thus, the fluid injected into such portion does not find low resistance pathways to theports vanes 9, the body 7 of therotor 3 and thestator 2, significantly improving the seal. - In the embodiment illustrated in
Figure 1 , the injection of fluid takes place through a calibratedradial hole 20 made in thestator barrel 4, and provided with a threadedfitting 21 for connection to a supply pipe. Conveniently, thefitting 21 is arranged in an initial area of the portion 18. - In the embodiment of
figure 2 , the injection takes place through a pair ofaxial holes 22 arranged one after the other in a circumferential direction and made in one of theheads 5. Conveniently, theholes 22 are shifted towards the rotor relative to a longitudinal centreline of thechamber 14 so as to lubricate the interlocking zone ofvanes 9 in theseats 10. - The operation of the
expander 1 is described below, with reference to its application to an energy recovery circuit, of whichfigures 3 and 4 illustrate two embodiments. -
Figure 3 illustrates a simple (non-recovery) ORC-typeenergy recovery circuit 25. The thermal source the residual energy of which is to be recovered is the lubricating oil of a compressor C. Thecircuit 25 uses an organic operating fluid, conveniently consisting of a hydrofluorocarbon (HFC) or a hydrofluoroolefin (HFO) to which a compatible lubricant is added, e.g. a polyester-based oil (POE), e.g. in a 5% by mass percentage. - The ORC circuit comprises:
- a circulation pump P pressurising the operating fluid in the liquid state,
- a first high temperature heat exchanger HTHX, or evaporator, wherein the operating fluid exchanges heat with the fluid of which the thermal energy is to be recovered, in the example illustrated the lubricating oil of the compressor, and passes to the vapour state;
- the
expander 1, wherein the operating fluid expands producing mechanical energy available to the rotor output shaft, to which an electric generator G is conveniently connected; and - a second low temperature heat exchanger LTHX, or condenser, wherein the operating fluid exchanges heat with a coolant fluid, conveniently water, for cooling and condensing the operating fluid.
- According to an embodiment example of the present invention, the operating fluid in the liquid state is drawn from the high pressure branch of the
circuit 25, i.e. downstream of the circulation pump, and is injected into theexpander 1 as described above. To such purpose, aduct 26 connects a node of the circuit downstream of the pump P to the fitting 21 or holes 22. - Preferably, in order to avoid temperature reductions inside the
compartment 15 which the liquid is injected into, this is preheated, e.g., by a third heat exchanger PXH in which it exchanges heat with the vapour at the outlet of theexpander 1. - According to an alternative not shown, the operating fluid in the liquid state may be preheated by the residual heat of the thermal source, in this case the compressor oil, rather than by the operating fluid in output from the expander.
- The circuit of
figure 4 , denoted by reference numeral 27, differs from that offigure 3 described in that it is a recovery circuit, i.e. in which all the operating fluid in output from the pump P is subjected to a heat exchange with the vapour at the outlet of theexpander 1 in a heat exchanger RHX or recovery heat exchanger. In this case, the operating fluid in liquid phase is drawn downstream of the RHX heat exchanger, and injected into theexpander 1. - The amount of operating fluid drawn and injected in the liquid state into the evaporator is conveniently less than 5% of the flow rate of the circulation pump P, and preferably less than 30, in order to avoid unwanted temperature drops in the expander compartments. Within these limits, the effects of the liquid injection are neutral or even favourable from a purely thermodynamic point of view, and very favourable from the point of view of the work indicated and the volumetric efficiency thanks to the improvement of the seal in the compartments.
Claims (14)
- A circuit for recovering energy from a thermal source comprising an operating fluid circulation pump (P), a high-temperature heat exchanger (HTHX) in which the operating fluid exchanges heat with the thermal source, a vane expander (1) and a low-temperature heat exchanger (LTHX) in which the operating fluid exchanges heat with a cooling fluid, the vane expander (1) comprising:- a stator (2) provided with an inlet port (16) for the operating fluid in the vapour state connected to a high temperature heat exchanger (HTHX) outlet and an outlet port (17) connected to a low temperature heat exchanger (LTHX) inlet,- a rotor (3) eccentrically housed in the stator (2) and provided with a body (7) internally tangent to an internal surface (6) of the stator (2) and with a plurality of vanes (9) sliding in respective seats (10) provided in the body (7) of the rotor (3) and pushed in a centrifugal direction for cooperating in a sealed manner with the internal surface (6),the stator (2) and the body (7) of the rotor (3) delimiting between one another a circumferential chamber (14) with variable radial width, communicating with the inlet port (16) and the outlet port (17) and divided by the vanes (9) into a plurality of compartments (15);comprising at least one supplementary inlet (20, 21; 22) for a supplementary inflow of operating fluid into an expansion portion (18) of the chamber (14) isolated from the inlet port (16) and from the outlet port (17), characterised in that the circuit comprises a supply duct (26) for supplying operating fluid in the liquid state from a high pressure branch of the circuit downstream of said circulation pump (P) and upstream of said high-temperature heat exchanger (HTHX) to said supplementary inlet (20;22) of the expander (1) .
- The circuit according to claim 1, characterised by comprising a heat exchanger (PHX) for preheating the operating fluid in the liquid state by means of the operating fluid flowing out of the expander (1) or the residual heat of the thermal source.
- The circuit according to claim 1, characterised by comprising a recovery heat exchanger (RHX) for exchanging heat between the operating fluid flowing out of the expander (1) and the operating fluid in the liquid state downstream of the circulation pump (P).
- The circuit according to claim 3, characterised in that the operating fluid in the liquid state injected into the expander (1) is drawn downstream of the recovery heat exchanger.
- The circuit according to any of the preceding claims, characterised in that said portion (18) of the chamber (14) is angularly spaced from each of the inlet (16) and outlet (17) ports by at least the angular width of a compartment (15) .
- The circuit according to any of the preceding claims, characterised in that the supplementary inlet comprises at least a radial hole (20) made in a stator barrel of said stator (2).
- The circuit according to one of the claims from 1 to 5, characterised in that the supplementary inlet comprises at least an axial hole (22) made in a head (5) of said stator (2) .
- A method for recovering energy from a thermal source by means of a circuit comprising an operating fluid circulation pump (P), a high-temperature heat exchanger (HTHX) in which the operating fluid exchanges heat with the thermal source, a vane expander (1) and a low-temperature heat exchanger (LTHX) in which the operating fluid exchanges heat with a cooling fluid, the vane expander (1) comprising:- a stator (2) provided with an inlet port (16) for the operating fluid in the vapour state connected to a high temperature heat exchanger (HTHX) outlet and an outlet port (17) connected to a low temperature heat exchanger (LTHX) inlet,- a rotor (3) eccentrically housed in the stator (2) and provided with a body (7) internally tangent to an internal surface (6) of the stator (2) and with a plurality of vanes (9) sliding in respective seats (10) provided in the body (7) of the rotor (3) and pushed in a centrifugal direction for cooperating in a sealed manner with the internal surface (6),the stator (2) and the body (7) of the rotor (3) delimiting between one another a circumferential chamber (14) with variable radial width, communicating with the inlet port (16) and the outlet port (17) and divided by the vanes (9) into a plurality of compartments (15),the expander comprising at least one supplementary inlet (20, 21; 22) for a supplementary inflow of operating fluid into an expansion portion (18) of the chamber (14) isolated from the inlet port (16) and from the outlet port (17),the method being characterized by comprising the steps of drawing operating fluid in the liquid state from a high pressure branch of the circuit downstream of said circulation pump (P) and upstream of said high-temperature heat exchanger (HTHX) and injecting the drawn operating fluid into said supplementary inlet (20, 21; 22) of the expander.
- The method according to claim 8, characterised by comprising a step of preheating the operating fluid in the liquid state by means of the operating fluid flowing out of the expander (1) or the residual heat of the thermal source before injecting said operating fluid into the expander (1).
- The method according to claim 8, characterised by comprising the step of exchanging heat between the operating fluid flowing out of the expander (1) and the operating fluid in the liquid state downstream of the circulation pump (P).
- The method according to claim 10, characterised in that the operating fluid in the liquid state injected into the expander (1) is drawn downstream of the recovery heat exchanger.
- The method according to one of the claims from 8 to 11, characterized in that the flow rate of operating fluid in the liquid state injected into the expander (1) is not more than 50 of the flow rate supplied by the pump (P).
- The method according to one of the claims from 8 to 12, characterized in that the operating fluid is an organic fluid with the addition of a lubricant.
- The method according to claim 13, characterised in that the organic fluid is a hydrofluorocarbon or a hydrofluoroolefin, and in that the lubricant is a polyester-based oil.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
IT201700151139 | 2017-12-29 | ||
PCT/IB2018/060700 WO2019130266A1 (en) | 2017-12-29 | 2018-12-28 | Energy recovery circuit from a thermal source and related energy recovery method |
Publications (2)
Publication Number | Publication Date |
---|---|
EP3732377A1 EP3732377A1 (en) | 2020-11-04 |
EP3732377B1 true EP3732377B1 (en) | 2023-05-10 |
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ID=61873794
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP18839731.9A Active EP3732377B1 (en) | 2017-12-29 | 2018-12-28 | Energy recovery circuit from a thermal source and related energy recovery method |
Country Status (2)
Country | Link |
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EP (1) | EP3732377B1 (en) |
WO (1) | WO2019130266A1 (en) |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6595024B1 (en) * | 2002-06-25 | 2003-07-22 | Carrier Corporation | Expressor capacity control |
US7607314B2 (en) * | 2006-12-15 | 2009-10-27 | Nissan Technical Center North America, Inc. | Air conditioning system |
WO2013042141A1 (en) * | 2011-09-19 | 2013-03-28 | Ing Enea Mattei S.P.A. | Bladed expander |
JP6423614B2 (en) * | 2014-05-13 | 2018-11-14 | 株式会社神戸製鋼所 | Thermal energy recovery device |
-
2018
- 2018-12-28 WO PCT/IB2018/060700 patent/WO2019130266A1/en unknown
- 2018-12-28 EP EP18839731.9A patent/EP3732377B1/en active Active
Also Published As
Publication number | Publication date |
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WO2019130266A1 (en) | 2019-07-04 |
EP3732377A1 (en) | 2020-11-04 |
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