![]() DEVICE FOR CONTROLLING A CLOSED CIRCUIT OPERATING ACCORDING TO A RANKINE CYCLE AND METHOD USING SUCH
专利摘要:
The present invention relates to a control device of a closed circuit (10) operating in a Rankine cycle, said circuit comprising a compression / circulation pump (12) of the fluid in liquid form, a heat exchanger (20) swept by a hot source (C) for evaporation of said fluid, means for expansion (32) of the fluid in vapor form, a cooling exchanger (44) swept by a cold source (F) for condensing the working fluid, a a working fluid reservoir (50), and working fluid flow lines (60, 62, 64, 66, 68). According to the invention, the tank (48) is connected to a pressure regulating device (52, 54). 公开号:FR3020090A1 申请号:FR1453388 申请日:2014-04-16 公开日:2015-10-23 发明作者:Pascal Smague 申请人:IFP Energies Nouvelles IFPEN; IPC主号:
专利说明:
[0001] The present invention relates to a control device of a closed circuit operating according to a Rankine cycle and to a method using such a device. [0002] As is widely known, the Rankine cycle is a thermodynamic cycle whereby heat from an external heat source is passed to a closed circuit that contains a working fluid. There are many types of Rankine cycle circuits, and more particularly those that involve a phase change (liquid / vapor) of a working fluid. This type of cycle is generally broken down into a step during which the working fluid used in liquid form is compressed isentropically, followed by a step where the compressed liquid fluid is heated and vaporized in contact with a heat source. This vapor is then expanded, in another step, isentropically in an expansion machine, then, in a final step, this expanded vapor is cooled and condensed in contact with a cold source. [0003] To perform these various steps, the circuit comprises a pump-compressor for circulating and compressing the fluid in liquid form, an evaporator which is swept by a hot fluid to achieve at least partial vaporization of the compressed fluid, a relaxation machine to relax steam, such as a turbine, which converts the energy of this steam into another energy, such as mechanical or electrical energy, and a condenser by which the heat contained in the steam is transferred to a cold source, usually outside air that sweeps this condenser, to turn this vapor into a fluid in liquid form. [0004] In this type of circuit, the fluid used is generally water, but other types of fluid, for example organic fluids or mixtures of organic fluids, can also be used. [0005] By way of example, these organic fluids may be butane, ethanol, hydrofluorocarbons, ammonia, carbon dioxide, etc. It is also known, in particular from document FR 2 884 555, to using the heat energy conveyed by the exhaust gases of an internal combustion engine, in particular that used for motor vehicles, as a hot source for heating and vaporizing the fluid passing through the evaporator. This makes it possible to improve the energy efficiency of this engine by recovering a large part of the energy lost in the exhaust to transform it into an energy that can be used for the motor vehicle through the Rankine cycle circuit. The Rankine cycle circuit thus improves the efficiency of the engine and contributes to the reduction of fuel consumption and pollutant emissions. In the context of mobile applications, particularly in the field of transport, access to a cold source for the condensation of the working fluid of the Rankine cycle circuit is not always obvious and, in some cases, can be expensive energetically . In addition, when using a low-boiling working fluid, such as organic fluids (especially HFC), to achieve an ORC (Organic Rankine Cycle), the attainment of condensation or sub-cooling of the fluid at the outlet of the condenser is not guaranteed. In the absence of sufficient subcooling of the fluid, a certain risk of cavitation at the inlet of the pump-compressor is to be expected in the event of a sudden drop in the pressure associated with the suction of the fluid at the inlet of the pump. pump. To guarantee the non-cavitation of the pump on the circuit, it is already known, in particular by US Pat. No. 7174732, to manage the subcooling by putting in place a forced ventilation at the condenser to increase its power. exchange and lower the temperature of the fluid output. [0006] This solution has the disadvantage of not being negligible to be energetically disadvantageous because it causes a significant energy consumption associated with ventilation, which is detrimental to the performance of the Rankine recovery cycle. [0007] The present invention proposes to overcome the above disadvantages by proposing an alternative to this drop in temperature while ensuring a lack of risk of cavitation at the pump inlet even in transient operation thereof. [0008] For this purpose, the invention relates to a device for controlling a closed circuit operating according to a Rankine cycle, said circuit comprising a compression pump / circulation fluid in liquid form, a heat exchanger swept by a hot source for evaporating said fluid, means for expanding the vapor-form fluid, a cooling exchanger cooled by a cold source for condensing the working fluid, a working fluid reservoir, and working fluid circulation lines, characterized in that the tank is connected to a pressure regulating device. [0009] The pressure regulating device may comprise an expander-pressure regulator associated with a discharge means. The discharge means may comprise a valve. [0010] The pressure regulator-regulator can be connected, on the one hand, to the reservoir and, on the other hand, to a source of pressure. The pressure source may include air or nitrogen. [0011] The reservoir may include an expandable portion for receiving the sky from the reservoir. The invention also relates to a control method of a closed circuit operating according to a Rankine cycle, said circuit comprising a compression pump / fluid circulation in liquid form, a heat exchanger swept by a hot source for the evaporation of said fluid, vapor-form fluid expansion means, a cold-source cooled heat exchanger for condensing the working fluid, a working fluid reservoir, and working fluid circulation lines, characterized in that it consists in regulating the pressure inside the tank. The method may consist in setting a regulator-regulator, connected to the tank, to a value such that the set pressure is around the saturation pressure of the fluid at the outlet of the cooling exchanger. The method may consist, when stopping the operation of the circuit, to produce a pressure above atmospheric pressure so as to prevent any introduction of outside air. [0012] The other features and advantages of the invention will appear on reading the following description, given solely by way of illustration and not limitation, and to which is appended the single figure which shows a control device of a closed circuit operating according to a Rankine cycle. [0013] In this figure, the Rankine cycle closed circuit 10 comprises a volumetric compression and circulation pump 12 of a working fluid, called pump in the following description for the sake of simplification, with an inlet 14 of the fluid of work in liquid form and an outlet 16 of this working fluid also in liquid form but compressed under high pressure. This pump is advantageously driven in rotation by an electric motor 18. The working fluid used is, here only by way of example, a fluid called R245fa (C3H3F5) from Honeywell or HFE7100 (C5H3F9O) from the company 3M or R365mfc (C4H5F5) from the company Solvay. This circuit also comprises a heat exchanger 20, called evaporator, traversed by the compressed working fluid between an inlet 22 of the liquid fluid and an outlet 24 through which the working fluid leaves the evaporator in the form of compressed steam. This evaporator is traversed by a hot source (Arrow C) from the exhaust gas flowing in the exhaust line 28 of an internal combustion engine 30 and more particularly of a motor vehicle engine. This circuit also comprises an expansion machine 32 receiving at its inlet 34 the working fluid in the form of vapor compressed at high pressure, this fluid emerging through the outlet 36 of this machine in the form of low-pressure expanded steam. Advantageously, this expansion machine may be in the form of an expansion turbine whose rotor is rotated by the working fluid in the form of steam by driving a connecting shaft 38. Preferably, this shaft makes it possible to transmit the energy recovered from any transformer device, such as an electric generator 40. This expansion machine may also be a reciprocating piston or rotary piston machine whose output shaft is connected to the transformer device. As illustrated in dashed lines in the figure, this expansion machine may also include a drive shaft 42 which connects the rotor of this machine to the rotor of the pump. In this configuration, the pump motor 18 can advantageously be eliminated and the rotor of this pump is then driven by the rotation of the rotor of the turbine to which it is connected by the shaft 42. The circuit further comprises a cooling exchanger 44, or condenser, with an inlet 46 for the reduced low pressure steam and an outlet 48 for the working fluid converted into liquid form after it has passed through this condenser. This condenser is swept by a cold source, usually a cold air flow (Arrow F) at room temperature, so as to cool the expanded steam so that it condenses and turns into a liquid. Of course, any other cold source of cooling, such as water, can be used to ensure condensation of the steam. This circuit also comprises a closed reservoir 50 which keeps the working fluid in the liquid state. [0014] This tank carries a pressure regulating device which comprises a pressure regulator-regulator 52 associated with a discharge means in the form of a discharge valve 54. The regulator-regulator is connected, on one side, to the sky. , generally air, present in the upper part of the tank 50 and, on the other hand, a pressure source 58 which is air or nitrogen under pressure. This regulator-regulator and the valve thus make it possible to ensure a controlled pressurization of the interior of the tank and more particularly of its sky. [0015] The different elements of the circuit are interconnected by fluid circulation lines 60, 62, 64, 66 and 68 for connecting the pump with the evaporator (evaporator line 60), the evaporator with the turbine (driving turbine 62), this turbine with the condenser (condenser line 64), the condenser with the pump (pump line 66), and this pump line to the tank (reservoir line 68). Additionally, the circuit comprises a temperature sensor 70 placed on the tank line 68 at the outlet of the condenser 44 and a pressure sensor 70 on the line 68 at the inlet of the pump 14. [0016] There is also provided a control unit 74 of the expander-regulator, and possibly of the relief valve 54, and which receives information from these sensors as well as any other sensors present in the circuit. [0017] During the operation of the circuit, the unit 74 controls the regulator-regulator 52 with a setting value such that the pressure in the reservoir 50 reaches the saturation pressure of the working fluid at the outlet of the condenser 44 with a margin of safety of cooling (10 ° C. for example). By way of example only, for a temperature measured by the sensor 70 at the outlet of the condenser of 85 ° C. corresponding to a saturation pressure of 4 bar of the working fluid, in the case of R365mfc for example, this regulator-regulator 52 is controlled to have a calibration value at a pressure of 5.2bar equivalent to the saturation pressure of the fluid at a temperature of 95 ° C. [0018] Thus configured, the regulator regulator ensures at all times that the fluid entering the pump has a sufficient level of subcooling (10 ° C in the example) with the almost total absence of fluid in vapor or gas phase , which avoids any risk of cavitation at the pump. [0019] In transient operation of the pump, the regulator regulator 52 associated with the relief valve 54 regulates the inlet pressure of this pump. This transient operation of the pump occurs during the transient operation of the heat source (increase or decrease in thermal energy) requiring a continuous adaptation of the coolant flow rate in the Rankine cycle to maintain stable temperature output of the heat sink. 'evaporator. Thus, when the pump increases its flow rate, the level of the working fluid present in the tank 50 will decrease. This lowering of the level then causes a drop in the pressure in the sky 56 of the reservoir. The pressure drop is then compensated by the setting in action of the regulator-regulator which will admit in this tank of the air or the nitrogen under pressure until reaching the desired level of pressure at the entrance of the pump in order to to be in a favorable condition of condensation at the outlet of the condenser Conversely, when the pump 12 reduces its flow circulated, the return of working fluid from the condenser 44 to the reservoir 50 is greater than the flow of fluid from this reservoir to the pump , the level in the tank will then increase causing an increase in the pressure in the sky 56. [0020] The relief valve is then controlled in opening, either by the unit 74, or automatically, to evacuate a portion of the gaseous fluid from the sky thereby limiting the increase in the pressure in the reservoir, which could adversely affect the efficiency of the recovery cycle. [0021] Of course, and without departing from the scope of the invention, it may be provided to carry out a variable adjustment of the pressure of the regulator-regulator which is slaved to the saturation pressure of the fluid temperature measured at the outlet of the condenser if this it is variable. [0022] Also, it may be provided to use a tank with an "expansible" sky, for example of the bladder type, to isolate the working fluid from the pressurization fluid in order to prevent a discharge to the atmosphere, by the discharge valve. , working fluid in vapor form if it is harmful to the environment. [0023] With this regulating device, it is ensured to have an optimal adjustment of the pressure in the low pressure part of the circuit (line 66, line 68 and reservoir 52). This makes it possible to have a good condensation of the working fluid and thus a lack of risk of cavitation for the pump while limiting the yield reduction of the recovery cycle inherent in the increase of the pressure in the low pressure part of the circuit. In addition, when the operation of the circuit is stopped, the elements of this circuit cool down to the temperature of its external environment, which in some cases may be less than zero degrees. Under these conditions, the pressure in the circuit will be established, without any particular device, the saturating vapor pressure of the fluid at this temperature. For certain heat transfer fluids, the saturation vapor pressure will be largely sub-atmospheric, creating a risk of air intrusion in the circuit during prolonged shutdowns. In order to guard against this effect which may impair the operation of the recovery circuit on a restart, the tank will be pressurized to a pressure slightly higher than atmospheric pressure via the expander-regulator, so that no air intrusion outside can not occur.
权利要求:
Claims (10) [0001] CLAIMS1) Control device of a closed circuit (10) operating in a Rankine cycle, said circuit comprising a compression / circulation pump (12) of the fluid in liquid form, a heat exchanger (20) swept by a hot source (C) for evaporation of said fluid, means for expanding (32) the fluid in vapor form, a cooling exchanger (44) swept by a cold source (F) for condensing the working fluid, a fluid reservoir working pump (50), and working fluid circulation lines (60, 62, 64, 66, 68), characterized in that the reservoir (48) is connected to a pressure regulating device (52, 54) . [0002] 2) Device according to claim 1, characterized in that the pressure regulating device comprises a pressure regulator (52) associated with a discharge means (54). [0003] 3) Device according to claim 2, characterized in that the discharge means comprises a valve (54). 20 [0004] 4) Device according to claim 2 or 3, characterized in that the pressure regulator (52) is connected, on the one hand, to the reservoir (50) and, on the other hand, to a pressure source (58). ). [0005] 5) Device according to claim 4, characterized in that the pressure source (58) comprises air or nitrogen. [0006] 6) Device according to one of the preceding claims, characterized in that the reservoir comprises an expandable portion for receiving the sky (56) of the reservoir. 30 [0007] 7) A method of controlling a closed circuit (10) operating in a Rankine cycle, said circuit comprising a compression / circulation pump (12) of the fluid in liquid form, a heat exchanger (20) swept by a hot source (C) for evaporation of said fluid, means for relaxing (32) the fluid in the vapor form, a cooling exchanger (44) swept by a cold source (F) for condensing the working fluid, a fluid reservoir of work (50), and circulating conduits of the working fluid (60, 62, 64, 66, 68), characterized in that it consists in regulating the pressure inside the reservoir. [0008] 8) Method according to claim 7, characterized in that it consists in setting a regulator-regulator (52), connected to the reservoir (50), to a value such that the calibration pressure is around the saturation pressure of the fluid at the outlet of the cooling exchanger (44). [0009] 9) A method according to claim 7, characterized in that it consists, when stopping the operation of the circuit, to produce a pressure greater than atmospheric pressure so as to prevent any introduction of outside air. [0010] 10 15
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同族专利:
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引用文献:
公开号 | 申请日 | 公开日 | 申请人 | 专利标题 EP0013045A1|1978-12-22|1980-07-09|GebràDer Sulzer Aktiengesellschaft|Steam-generation plant| DE19524171A1|1995-07-03|1997-01-09|Rauscher Georg|Low temp thermal energy machine - has closed liquid gas circuit for extraction of heat energy from ambient air or working machine| DE19853206C1|1998-11-18|2000-03-23|Siemens Ag|Feed-water vessel condensate warm-up device e.g. for steam electric power station| WO2011057724A2|2009-11-14|2011-05-19|Orcan Energy Gmbh|Thermodynamic machine and method for the operation thereof| JPS6249444B2|1982-02-22|1987-10-20|Mitsubishi Heavy Ind Ltd| JPH0229842B2|1983-09-07|1990-07-03|Tadao Kitajima| JPS6213490B2|1985-03-27|1987-03-26|Hitachi Ltd| JP2703123B2|1991-02-04|1998-01-26|三菱重工業株式会社|Power plant| US6571548B1|1998-12-31|2003-06-03|Ormat Industries Ltd.|Waste heat recovery in an organic energy converter using an intermediate liquid cycle| DE10228868B4|2002-06-27|2005-11-17|Enginion Ag|Steam engine with closed circuit| US7174732B2|2003-10-02|2007-02-13|Honda Motor Co., Ltd.|Cooling control device for condenser| FR2884555A1|2005-04-13|2006-10-20|Peugeot Citroen Automobiles Sa|Vehicle IC engine energy recuperator has nitrogen oxide trap in exhaust line and Rankine cycle system with loop containing compressor and evaporator| US20070101989A1|2005-11-08|2007-05-10|Mev Technology, Inc.|Apparatus and method for the conversion of thermal energy sources including solar energy| JP2009041409A|2007-08-07|2009-02-26|Toyota Motor Corp|Waste heat recovery device and path internal pressure holding device| US7735323B2|2008-02-12|2010-06-15|Lawrence Livermore National Security, Llc|Solar thermal power system| DE102009050068A1|2009-10-14|2011-04-21|Daimler Ag|Internal combustion engine has cooling circuit and Clausius-Rankine cycle for waste heat recovery, where Clausius-Rankine cycle is connected with cooling circuit in heat transmitting manner by heat exchanger device| SE535453C2|2010-12-01|2012-08-14|Scania Cv Ab|Arrangement and method for converting thermal energy into mechanical energy| DE102010054733A1|2010-12-16|2012-06-21|Daimler Ag|Waste heat recovery device, operating method| DE102012000100A1|2011-01-06|2012-07-12|Cummins Intellectual Property, Inc.|Rankine cycle-HEAT USE SYSTEM| JP5827480B2|2011-03-28|2015-12-02|株式会社神戸製鋼所|Power generator| CN102230401B|2011-05-19|2014-03-12|西安交通大学|Replacement system of organic Rankine cycle low-temperature power generation working medium and replacement method thereof| US20120325436A1|2011-06-27|2012-12-27|Shedd Timothy A|High efficiency thermal management system| FR2985767B1|2012-01-18|2019-03-15|IFP Energies Nouvelles|DEVICE FOR CONTROLLING A WORKING FLUID IN A CLOSED CIRCUIT OPERATING ACCORDING TO A RANKINE CYCLE AND METHOD USING SUCH A DEVICE| DE102013211875A1|2013-06-24|2015-01-08|Robert Bosch Gmbh|Waste heat recovery system for an internal combustion engine| DE102014223626A1|2013-11-20|2015-05-21|MAHLE Behr GmbH & Co. KG|Apparatus and method for recovering waste heat energy and a utility vehicle| DE102014206038A1|2014-03-31|2015-10-01|Mtu Friedrichshafen Gmbh|System for a thermodynamic cycle, control system for a system for a thermodynamic cycle, method for operating a system, and arrangement with an internal combustion engine and a system|US9784141B2|2015-01-14|2017-10-10|Ford Global Technologies, Llc|Method and system of controlling a thermodynamic system in a vehicle| DE102015215063A1|2015-08-06|2017-02-09|Mahle International Gmbh|Container for a waste heat recovery cycle| DE102016212232A1|2016-07-05|2018-01-11|Mahle International Gmbh|Waste heat utilization device| FR3055149B1|2016-08-18|2020-06-26|IFP Energies Nouvelles|CLOSED CIRCUIT OPERATING ACCORDING TO A RANKINE CYCLE WITH A DEVICE FOR EMERGENCY STOPPING OF THE CIRCUIT AND METHOD USING SUCH A CIRCUIT| DE102016222927A1|2016-11-21|2018-05-24|Mahle International Gmbh|heat recovery device| KR101868271B1|2017-03-20|2018-06-15|두산중공업 주식회사|Device and method for suppling of working fuid| KR101868273B1|2017-03-28|2018-06-15|두산중공업 주식회사|Control device for suppling of working fluid| FR3069912B1|2017-08-02|2020-07-03|Commissariat A L'energie Atomique Et Aux Energies Alternatives|DEVICE FOR REGULATING THE FLUIDIC LOAD IN CIRCULATION IN A RANKINE CYCLE BASED SYSTEM| US11136905B2|2017-09-22|2021-10-05|Tenneco Gmbh|Rankine power system with working fluid tank and control system| JP6996208B2|2017-10-05|2022-01-17|いすゞ自動車株式会社|Rankine cycle system and its control method| SE541729C2|2017-12-11|2019-12-03|Scania Cv Ab|A device and a method for volume compensation and pressure control of a working medium in a WHR-system| FR3084913B1|2018-08-09|2020-07-31|Faurecia Systemes Dechappement|RANKINE CIRCUIT THERMAL SYSTEM| EP3879082A1|2020-03-12|2021-09-15|Volvo Car Corporation|A tank pressure regulation system for a waste heat recovery system|
法律状态:
2016-04-20| PLFP| Fee payment|Year of fee payment: 3 | 2017-04-26| PLFP| Fee payment|Year of fee payment: 4 | 2018-04-13| PLFP| Fee payment|Year of fee payment: 5 | 2019-04-25| PLFP| Fee payment|Year of fee payment: 6 | 2020-04-29| PLFP| Fee payment|Year of fee payment: 7 | 2021-04-27| PLFP| Fee payment|Year of fee payment: 8 |
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申请号 | 申请日 | 专利标题 FR1453388|2014-04-16| FR1453388A|FR3020090B1|2014-04-16|2014-04-16|DEVICE FOR CONTROLLING A CLOSED CIRCUIT OPERATING ACCORDING TO A RANKINE CYCLE AND METHOD USING SUCH A DEVICE|FR1453388A| FR3020090B1|2014-04-16|2014-04-16|DEVICE FOR CONTROLLING A CLOSED CIRCUIT OPERATING ACCORDING TO A RANKINE CYCLE AND METHOD USING SUCH A DEVICE| EP15305403.6A| EP2933444A1|2014-04-16|2015-03-19|Device for controlling a closed circuit operating according to a Rankine cycle and method using such a device| US14/671,088| US10634011B2|2014-04-16|2015-03-27|System and method for controlling a closed loop working on a rankine cycle with a tank and a pressure regulating device| JP2015082279A| JP6660095B2|2014-04-16|2015-04-14|Apparatus for controlling a closed loop operating according to a Rankine cycle and method of using the same| CN201510277598.3A| CN105042952B|2014-04-16|2015-04-14|Device for controlling a closed circuit operating with a rankine cycle and method for using same| 相关专利
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