US20070095085A1 - Air-Conditioning Assembly - Google Patents

Air-Conditioning Assembly Download PDF

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Publication number
US20070095085A1
US20070095085A1 US10/578,462 US57846204A US2007095085A1 US 20070095085 A1 US20070095085 A1 US 20070095085A1 US 57846204 A US57846204 A US 57846204A US 2007095085 A1 US2007095085 A1 US 2007095085A1
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United States
Prior art keywords
refrigerant
inlet
expander
compressor
pressure
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US10/578,462
Inventor
Jin Liu
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Valeo Systemes Thermiques SAS
Teledyne e2v Semiconductors SAS
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Individual
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Assigned to ATMEL GRENOBLE reassignment ATMEL GRENOBLE ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: BRISSOT, LOUIS, RAMEL, ROMAIN
Assigned to VALEO SYSTEMES THERMIQUES S.A.S. reassignment VALEO SYSTEMES THERMIQUES S.A.S. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: BEN YAHIA, MOHAMED, LIU, JIN MING, MEURILLON, PAUL
Publication of US20070095085A1 publication Critical patent/US20070095085A1/en
Abandoned legal-status Critical Current

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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60HARRANGEMENTS OF HEATING, COOLING, VENTILATING OR OTHER AIR-TREATING DEVICES SPECIALLY ADAPTED FOR PASSENGER OR GOODS SPACES OF VEHICLES
    • B60H1/00Heating, cooling or ventilating [HVAC] devices
    • B60H1/32Cooling devices
    • B60H1/3204Cooling devices using compression
    • B60H1/3205Control means therefor
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25BREFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B41/00Fluid-circulation arrangements
    • F25B41/30Expansion means; Dispositions thereof
    • F25B41/31Expansion valves
    • F25B41/34Expansion valves with the valve member being actuated by electric means, e.g. by piezoelectric actuators
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25BREFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B9/00Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
    • F25B9/002Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the refrigerant
    • F25B9/008Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the refrigerant the refrigerant being carbon dioxide
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60HARRANGEMENTS OF HEATING, COOLING, VENTILATING OR OTHER AIR-TREATING DEVICES SPECIALLY ADAPTED FOR PASSENGER OR GOODS SPACES OF VEHICLES
    • B60H1/00Heating, cooling or ventilating [HVAC] devices
    • B60H1/32Cooling devices
    • B60H2001/3236Cooling devices information from a variable is obtained
    • B60H2001/3248Cooling devices information from a variable is obtained related to pressure
    • B60H2001/3254Cooling devices information from a variable is obtained related to pressure of the refrigerant at an expansion unit
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60HARRANGEMENTS OF HEATING, COOLING, VENTILATING OR OTHER AIR-TREATING DEVICES SPECIALLY ADAPTED FOR PASSENGER OR GOODS SPACES OF VEHICLES
    • B60H1/00Heating, cooling or ventilating [HVAC] devices
    • B60H1/32Cooling devices
    • B60H2001/3236Cooling devices information from a variable is obtained
    • B60H2001/3255Cooling devices information from a variable is obtained related to temperature
    • B60H2001/3263Cooling devices information from a variable is obtained related to temperature of the refrigerant at an evaporating unit
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60HARRANGEMENTS OF HEATING, COOLING, VENTILATING OR OTHER AIR-TREATING DEVICES SPECIALLY ADAPTED FOR PASSENGER OR GOODS SPACES OF VEHICLES
    • B60H1/00Heating, cooling or ventilating [HVAC] devices
    • B60H1/32Cooling devices
    • B60H2001/3269Cooling devices output of a control signal
    • B60H2001/3285Cooling devices output of a control signal related to an expansion unit
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25BREFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2309/00Gas cycle refrigeration machines
    • F25B2309/06Compression machines, plants or systems characterised by the refrigerant being carbon dioxide
    • F25B2309/061Compression machines, plants or systems characterised by the refrigerant being carbon dioxide with cycle highest pressure above the supercritical pressure
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25BREFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2341/00Details of ejectors not being used as compression device; Details of flow restrictors or expansion valves
    • F25B2341/06Details of flow restrictors or expansion valves
    • F25B2341/063Feed forward expansion valves
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25BREFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2500/00Problems to be solved
    • F25B2500/19Calculation of parameters
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25BREFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2600/00Control issues
    • F25B2600/17Control issues by controlling the pressure of the condenser
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25BREFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2700/00Sensing or detecting of parameters; Sensors therefor
    • F25B2700/13Mass flow of refrigerants
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02BCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B30/00Energy efficient heating, ventilation or air conditioning [HVAC]
    • Y02B30/70Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating

Definitions

  • the invention relates to motor vehicle air conditioning circuits.
  • the compressor of the air conditioning circuit is driven by the engine and therefore consumes part of the engine's power.
  • This drawback is problematic in the case of mechanical compressors with an external control, the use of which is commonplace.
  • the fuel injection computer of the vehicle does not have the instantaneous value of the actual power absorbed by the compressor and therefore chooses, for the operation of the compressor, fuel injection parameters by default, which correspond to the maximum value of the power absorbed, which value is rarely reached in practice.
  • one solution for optimizing the efficiency of the engine consists in estimating the instantaneous value of this power actually absorbed by the compressor. When this information is known, it is then possible to adapt the fuel injection parameters of the engine to the actual requirements.
  • the CO 2 refrigerant has a much smaller global warming effect than subcritical refrigerants, such as the HFC refrigerants of the R134a type.
  • An air conditioning circuit using a supercritical fluid comprises a compressor, a gas cooler, an internal heat exchanger, an expander and an evaporator, the refrigerant passing through these in the above order.
  • the cooling of the refrigerant after compression undergoes no phase change.
  • the refrigerant passes into the liquid state only during the expansion.
  • US 2003/0115896 A1 proposes an air conditioning unit for estimating the mass flow rate of a supercritical refrigerant, based on a measurement of the high pressure and a measurement of the low pressure.
  • the air conditioning circuit in order for the estimate for the mass flow rate to be sufficiently accurate, it is necessary for the air conditioning circuit to be controlled so that the refrigerant leaving the expander is almost entirely in the liquid state.
  • a sensor is required for measuring the low pressure, which increases the cost of the air conditioning unit.
  • French patent application 03/03362 also proposes an air conditioning unit for estimating the mass flow rate of a supercritical refrigerant.
  • the proposed air conditioning unit includes a calculating function that uses two differences in temperature relating to the gas cooler, at least one of which is based on the temperature of the refrigerant at a chosen intermediate point on the gas cooler. This intermediate point is in particular located at a distance x i from the inlet of the gas cooler that is between 5% and 35% of the total length of the gas cooler.
  • this assembly requires a large number of sensors (sensors for measuring the refrigerant pressure at the inlet and outlet of the compressor, the temperature of the refrigerant at the inlet of the gas cooler, the temperature of the stream of air received by the gas cooler and the temperature of the refrigerant at the chosen intermediate point on the gas cooler), which therefore increases the cost of the assembly.
  • the subject of the present invention is an air conditioning unit that remedies these known drawbacks of the prior art.
  • the invention proposes a motor vehicle air conditioning unit, provided with a supercritical refrigerant circuit comprising a compressor, a gas cooler, an expander, defining a refrigerant flow area, and an evaporator.
  • the assembly further includes an electronic control device designed to interact with the refrigerant circuit.
  • the electronic control device includes a calculating function using an estimate of the flow area of the expander, the density of the refrigerant and the pressure of the refrigerant at the inlet of the expander in order to calculate an estimate of the refrigerant mass flow rate at the expander.
  • the flow area of the expander is estimated from the refrigerant pressure at the inlet of the expander.
  • the electronic control device may be capable of reacting to the fact that the value of the refrigerant pressure P 20 at the inlet of the expander is:
  • the first pressure value P 1 is approximately equal to 80 bar
  • the second pressure value P 2 is approximately equal to 110 bar
  • the third pressure value P 3 is approximately equal to 135 bar
  • the first constant S 1 is approximately equal to 0.07 mm 2
  • the second constant S 2 is approximately equal to 0.5 mm 2
  • the third constant S 3 is approximately equal to 0.78 mm 2
  • the fourth constant S 4 is approximately equal to 3.14 mm 2 .
  • the calculating function is specific to calculating the density of the refrigerant from the refrigerant temperature at the inlet of the expander and from the refrigerant pressure at the inlet of the expander.
  • the air conditioning unit may include a probe placed at the inlet of the expander for measuring the refrigerant temperature at the inlet of the expander.
  • the air conditioning unit may also include a sensor placed at the inlet of the expander for measuring the refrigerant pressure at the inlet of the expander.
  • the electronic control device may include a power estimation function capable of estimating the power absorbed by the compressor from:
  • the electronic control device is capable of estimating the work of the compressor from the refrigerant pressure at the inlet of the expander, from the refrigerant pressure at the inlet of the compressor and from a refrigerant temperature relative to the compressor.
  • the refrigerant pressure at the inlet of the compressor is estimated from a pressure at the inlet or at the outlet of the evaporator combined with the refrigerant mass flow rate.
  • the pressure at the inlet or at the outlet of the evaporator is determined from the refrigerant temperature, said temperature being either measured by a probe or estimated from:
  • the refrigerant temperature relative to the compressor may be the refrigerant temperature at the inlet of the compressor.
  • the air conditioning unit may then include a probe placed at the inlet of the compressor for measuring the refrigerant temperature at the inlet of the compressor.
  • the refrigerant temperature relative to the compressor may be the refrigerant temperature at the outlet of the compressor.
  • the air conditioning installation may then include a probe placed at the outlet of the compressor for measuring the refrigerant temperature at the outlet of the compressor.
  • the invention also covers a product-program, which may be defined as comprising the functions used for estimating the refrigerant mass flow rate and the power consumed by the compressor.
  • FIG. 1A is a diagram of a motor vehicle air conditioning circuit operating with a supercritical refrigerant
  • FIG. 1B is a diagram of an air conditioning unit according to the invention.
  • FIG. 2 is a plot showing the variations in the flow area of the expander as a function of the refrigerant pressure at the inlet of the expander;
  • FIG. 3 is a flow diagram showing the steps implemented by the control device for estimating the refrigerant mass flow rate at the expander;
  • FIG. 4 is a flow diagram showing the steps implemented by the control device for estimating the flow area of the expander
  • FIG. 5 is a flow diagram representing the steps implemented by the control device for estimating the power consumed by the compressor, according to the invention.
  • FIGS. 6 and 7 are diagrams of the air conditioning circuit according to alternative embodiments of the invention.
  • FIGS. 8 to 12 are schematic diagrams showing the position of the temperature probes used for determining the pressure at the inlet or at the outlet of the evaporator;
  • FIG. 13 illustrates the method of determining the pressure of the refrigerant at the inlet of the compressor
  • FIG. 14 shows the relationship between the refrigerant mass flow rate and the refrigerant pressure at the inlet of the compressor.
  • Appendix A comprises the main mathematical equations used for implementing the assembly.
  • FIG. 1A represents an air conditioning circuit through which a supercritical refrigerant flows.
  • the description will refer to the supercritical refrigerant CO 2 as a nonlimiting example.
  • Such a circuit conventionally comprises:
  • the circuit may further include an internal heat exchanger 23 , allowing the refrigerant flowing from the gas cooler to the expander to give up heat to the refrigerant flowing from the evaporator to the compressor.
  • the circuit may further include an accumulator 17 placed between the outlet of the evaporator and the inlet of the compressor, in order to avoid liquid surges.
  • the gas cooler 11 receives a stream of external air 16 for extracting the heat taken from the passenger compartment, which stream under certain operating conditions is blown by a motor/fan unit 15 .
  • the evaporator 13 receives a stream of air from a blower, in order to produce a stream of conditioned air 21 .
  • the expander 12 may have a variable flow area, such as an electronic expander, a thermostatic expander or any other expander for which the flow area depends on the high pressure.
  • the expander 12 may also have a fixed flow area, such as a calibrated orifice.
  • the supercritical refrigerant is compressed in the gaseous phase and raised to a high pressure by the compressor 14 .
  • the gas cooler 11 then cools the refrigerant by means of the incoming stream of air 16 .
  • the cooling of the refrigerant after compression does not involve a phase change.
  • the refrigerant passes to the two-phase state, with a vapor content that depends on the low pressure, only during the expansion.
  • the internal heat exchanger 23 allows the refrigerant to be very strongly cooled.
  • FIG. 1B this shows an air conditioning unit according to the invention installed in a motor vehicle.
  • the motor vehicle is driven by an engine 43 , which may be controlled by a fuel injection computer 42 .
  • the fuel injection computer 42 receives information from various sensors, which it interprets in order to adjust the injection parameters.
  • the fuel injection computer 42 may also provide information about the conditions inside or outside the vehicle (information provided by a solar sensor, number of occupants, etc.). In particular, it may provide information about instantaneous values relating to the operation of the vehicle, and especially about the rotational speed N of the compressor.
  • the unit is also provided with an air conditioning computer 40 , comprising a passenger compartment regulator 41 and an air conditioning loop regulator 402 .
  • the passenger compartment regulator 41 is designed to set the temperature setpoint of the external air blown into the evaporator 13 .
  • the engine fuel injection computer may act on the air conditioning unit via an air conditioning regulator 402 . This link may prevent the operation of the air conditioning unit when the engine is on high load.
  • the air conditioning unit according to the invention is based on a model of the expander, in order to provide an estimate of the refrigerant mass flow rate m exp at the expander.
  • the air conditioning unit includes an electronic control device, for example an electronic card 401 , designed to interact with the air conditioning circuit 10 via the links 30 / 31 and with the fuel injection computer 42 via the links 32 / 33 .
  • an electronic control device for example an electronic card 401 , designed to interact with the air conditioning circuit 10 via the links 30 / 31 and with the fuel injection computer 42 via the links 32 / 33 .
  • the electronic card 401 may be considered as an integral part of the vehicle air conditioning computer 40 .
  • the electronic card 401 may receive information 30 coming from sensors fitted on the air conditioning circuit 10 . It may also receive information from the engine fuel injection computer 42 via the link 33 , in particular the rotation speed N of the compressor and/or the run speed V of the vehicle.
  • the expander may be modelled by equation A10 of Appendix A, where K is a coefficient that characterizes the expander, in particular its pressure drop.
  • the calculating function can calculate an estimate of the refrigerant mass flow rate m exp at the expander from:
  • the density ⁇ of the CO 2 refrigerant may be estimated from the temperature T 30 at the inlet of the expander and from the pressure P 20 at the inlet of the expander, according to equation A11 of Appendix A.
  • the Applicant has furthermore found that the flow area S (in mm 2 ) of an expander with a flow area depends on the refrigerant pressure P 20 at the inlet of the expander.
  • an estimate of the refrigerant mass flow rate m exp at the expander may be obtained from the refrigerant pressure P 20 at the inlet of the expander and from the temperature T 30 at the inlet of the expander.
  • the refrigerant pressure P 20 at the inlet of the expander and the refrigerant temperature T 30 at the inlet of the expander may be estimated or measured.
  • the air conditioning circuit may include two separate sensors for measuring the refrigerant pressure P 20 at the inlet of the expander and the refrigerant temperature T 30 at the inlet of the expander, respectively.
  • the air conditioning circuit may have a single sensor placed at the inlet of the expander for measuring both these quantities.
  • FIG. 2 is a plot showing the variation in the flow area S (in mm 2 ) as a function of the refrigerant pressure P 20 (in bar) at the inlet of the expander. The curves shown on this plot correspond to equations A2 to A5 of Appendix A.
  • the area S is equal to a first constant S 1 according to equation A2 of Appendix A.
  • the area S follows a straight line whose directrix is determined from the values of S 1 , P 1 , P 2 and a second constant S 2 , in accordance with equation A3 of Appendix A.
  • the value of S 2 corresponds to the value of the area S when P 20 is equal to the valave P 2 .
  • the area S follows a straight line whose directrix is determined from the values of S 2 , P 2 , P 3 and a third constant S 3 in accordance with equation A4 of Appendix A.
  • the first pressure value P 1 may be approximately equal to 80 bar
  • the second pressure value P 2 may be approximately equal to 110 bar
  • the third pressure value P 3 may be approximately equal to 135 bar
  • the first constant S 1 may be approximately equal to 0.07 mm 2
  • the second constant S 2 may be approximately equal to 0.5 mm 2
  • the third constant S 3 may be approximately equal to 0.78 mm 2
  • the fourth constant S 4 may be approximately equal to 3.14 mm 2 .
  • the estimate of the refrigerant mass flow rate, provided by the calculating function of the electronic card may be used to calculate the mechanical power absorbed.
  • the electronic card includes a power estimation function capable of estimating the power P abs absorbed by the compressor from the refrigerant mass flow rate m exp .
  • the power estimation function is capable of estimating the power P abs absorbed by the compressor from the isentropic work of compression W ise and from the rotation speed N of the compressor in accordance with equation A6 of Appendix A.
  • the coefficients a and b are related to operating parameters of the air conditioning circuit.
  • the coefficient a corresponds to the mechanical efficiency relative to the isentropic compression of the compressor and is around 1.38.
  • the coefficient b is the image of the compressor efficiency and corresponds to the friction factor of the compressor.
  • the refrigerant pressure P 35 at the inlet of the compressor and the temperature of the refrigerant T comp relative to the compressor may be estimated or measured.
  • the pressure of the refrigerant at the inlet of the compressor is estimated using the refrigerant mass flow rate m exp calculated above and from the pressure drop ⁇ p between the inlet of the evaporator 13 and the inlet of the compressor 14 .
  • this estimate of the refrigerant pressure at the inlet of the compressor may be determined using the refrigerant mass flow rate m exp calculated above and from the pressure drop ⁇ p between the outlet of the evaporator 13 and the inlet of the compressor 14 .
  • the speed of the refrigerant V co 2 can be determined from:
  • This saturation temperature T 50 of the pressure refrigerant may be measured or estimated.
  • equation A91 of Appendix A is used, in which:
  • FIGS. 8 and 9 illustrate the possibility of measuring the saturation temperature T 50 of the refrigerant at the inlet of the evaporator 13 either by means of an intrusive or direct temperature probe 51 , that is to say a probe directly bathed by the refrigerant ( FIG. 7 ), or by a nonintrusive or indirect probe 52 , which measures the temperature of the refrigerant on the basis of the temperature of the tube that is transporting it ( FIG. 8 ).
  • an intrusive or direct temperature probe 51 that is to say a probe directly bathed by the refrigerant ( FIG. 7 )
  • a nonintrusive or indirect probe 52 which measures the temperature of the refrigerant on the basis of the temperature of the tube that is transporting it ( FIG. 8 ).
  • FIGS. 10 and 11 show the possibility of measuring the saturation temperature T 50 of the refrigerant at the outlet of the evaporator 13 using means identical to the temperature measurement envisaged at the inlet of the evaporator 13 .
  • FIG. 13 This method of determining the refrigerant pressure at the inlet of the compressor is summarized in FIG. 13 in the form of a block diagram in which:
  • FIG. 14 illustrates the relationship between the refrigerant mass flow rate and the refrigerant pressure P 35 at the inlet of the compressor.
  • the x-axis of this curve represents the mass flow rate m exp in kilograms per hour and the y-axis of this curve illustrates the pressure drop ⁇ p in bar between the inlet or the outlet of the evaporator 13 and the inlet of the compressor 14 . It may be seen that an error of around 30 kg in the estimate of the mass flow rate results in an error of around 2 bar in the determination of P 35 . This error is minor compared with the absolute operating pressure values, which are often greater than 35 bar.
  • the refrigerant temperature relative to the compressor may be the refrigerant temperature T 35 at the inlet of the compressor, in accordance with equation A81 of Appendix A.
  • R is the perfect gas constant and M corresponds to the molar mass of the refrigerant.
  • the ratio R/M may especially be equal to 188.7.
  • the refrigerant temperature relative to the compressor may be the refrigerant temperature T 36 at the outlet of the compressor in accordance with equation A82 of Appendix A.
  • FIG. 3 is a flow diagram showing the steps implemented by the electronic card for estimating the refrigerant mass flow rate m exp and the power consumed by the compressor.
  • the refrigerant pressure P 20 at the inlet of the expander is estimated/measured.
  • the refrigerant pressure P 20 at the inlet of the expander may be measured by a sensor 20 placed at the inlet of the expander.
  • the pressure P 20 of the refrigerant at the inlet of the expander may be estimated.
  • the electronic card 401 estimates the flow area S of the expander 12 from the measured/estimated refrigerant pressure value P 20 at the inlet of the expander in accordance with equations A4 and A5 of Appendix A.
  • Step 102 is shown in detail in the flow diagram of FIG. 4 .
  • the electronic card determines if the measured value of the refrigerant pressure P 20 at the inlet of the expander is:
  • the electronic card provides an estimate/measurement of the temperature T 30 at the inlet of the expander.
  • the unit may include a temperature sensor 30 for measuring the refrigerant temperature T 30 at the inlet of the expander, as shown in FIGS. 1B, 6 and 7 .
  • the unit may include a single sensor 20 for measuring both the pressure P 20 and the temperature T 30 of the refrigerant at the inlet of the expander.
  • the refrigerant temperature T 30 at the inlet of the expander may also be estimated.
  • the electronic card 401 estimates the density ⁇ of the CO 2 refrigerant.
  • the density ⁇ of the CO 2 refrigerant may be calculated according to equation A11 of Appendix A from the refrigerant pressure P 20 at the inlet of the expander, obtained at step 100 , and from the refrigerant temperature T 30 at the inlet of the expander, obtained at step 103 .
  • the electronic card 401 can then calculate the refrigerant mass flow rate m exp according to equation A3 of Appendix A, from:
  • the estimate of the refrigerant mass flow rate m exp at the expander may be used to calculate the power P abs consumed by the compressor.
  • FIG. 5 is a flow diagram showing the steps implemented by the electronic card for calculating the power P abs consumed by the compressor from the estimate of the refrigerant mass flow rate m exp at the expander.
  • the estimate of the power absorbed by the compressor may in particular require a prior estimate of the work ⁇ H ise of the compressor, in accordance with equations A6 and A7 of Appendix A.
  • the electronic card calculates an estimate of the work ⁇ H ise of the compressor in accordance with equation A8 of Appendix A from:
  • the refrigerant temperature relative to the compressor is the refrigerant temperature T 35 at the inlet of the compressor (in accordance with equation A81 of Appendix A), it can be measured by a probe 35 placed at the inlet of the compressor, as shown in FIGS. 1B and 6 .
  • the refrigerant temperature relative to the compressor is the refrigerant temperature T 36 at the outlet of the compressor (in accordance with equation A82 of Appendix A), it can be measured by a probe 36 placed at the outlet of the compressor, as shown in FIG. 7 .
  • the refrigerant pressure P 12 at the inlet of the compressor may be estimated or measured.
  • the electronic card calculates the isentropic power W ise from the refrigerant mass flow rate m exp obtained at step 105 and the work ⁇ H ise of the compressor obtained at step 200 , in accordance with equation A7 of Appendix A.
  • the electronic card calculates an estimate of the power P abs absorbed by the compressor, according to equation A6 of Appendix A, from the isentropic power W ise obtained at step 202 and the rotation speed N of the compressor.
  • the rotation speed N of the compressor is supplied to the electronic card by the engine fuel injection computer 42 via the link 33 , with reference to FIG. 1B .
  • the computer may use the estimated value of the actual power consumed by the compressor to adjust the injection parameters, thereby making it possible to reduce the fuel consumption.
  • the air conditioning unit according to the invention makes it possible to obtain a satisfactory estimate of the refrigerant mass flow rate at the expander. Furthermore, this unit does not use a low-pressure sensor to estimate the refrigerant mass flow rate at the expander, thereby allowing the total cost of the unit to be reduced.
  • the present invention also covers the software code that it uses, most particularly when this is available on any medium that can be read by a computer.
  • the expression “medium that can be read by a computer” covers a storage medium, for example a magnetic or optical storage medium, and also a transmission means, such as a digital or analog signal.

Abstract

The invention relates to a motor vehicle air-conditioning assembly provided with a supercritical fluid refrigerant circuit and comprising a pressure relief member (12) defining a cross-section of fluid flow. The assembly comprises an electronic control device (401) for interacting with the fluid refrigerant circuit. The electronic control device includes a computing function using an estimation of the cross-section of flow of the pressure relief member, the density coefficient of the fluid refrigerant, and the pressure of the fluid refrigerant at the inlet of the pressure relief member for calculating an estimation of the mass flow rate of the fluid refrigerant in the pressure relief member (12).

Description

  • The invention relates to motor vehicle air conditioning circuits.
  • In conventional motor vehicles, the compressor of the air conditioning circuit is driven by the engine and therefore consumes part of the engine's power. The power absorbed by the compressor, when it is operating, reduces the efficiency of the engine and consequently increases the fuel consumption and the pollution generated by the exhaust gases from the vehicle. This drawback is problematic in the case of mechanical compressors with an external control, the use of which is commonplace.
  • Moreover, in existing constructions, the fuel injection computer of the vehicle does not have the instantaneous value of the actual power absorbed by the compressor and therefore chooses, for the operation of the compressor, fuel injection parameters by default, which correspond to the maximum value of the power absorbed, which value is rarely reached in practice.
  • Consequently, one solution for optimizing the efficiency of the engine consists in estimating the instantaneous value of this power actually absorbed by the compressor. When this information is known, it is then possible to adapt the fuel injection parameters of the engine to the actual requirements.
  • In existing constructions, an estimate of the refrigerant mass flow rate is used to calculate the instantaneous power absorbed by the compressor.
  • Such constructions generally involving subcritical refrigerants are unsuitable for supercritical refrigerants.
  • The use of supercritical refrigerants, especially the CO2 refrigerant R744, was developed for vehicle air conditioning circuits in order to limit the deleterious effects of refrigerants on the environment. The CO2 refrigerant has a much smaller global warming effect than subcritical refrigerants, such as the HFC refrigerants of the R134a type.
  • An air conditioning circuit using a supercritical fluid comprises a compressor, a gas cooler, an internal heat exchanger, an expander and an evaporator, the refrigerant passing through these in the above order. In such a circuit, the cooling of the refrigerant after compression undergoes no phase change. The refrigerant passes into the liquid state only during the expansion. This property of supercritical fluids means that the assembly given in patent application 01/16568 cannot be used to estimate the supercritical refrigerant flow rate and the power consumed by the compressor.
  • US 2003/0115896 A1 proposes an air conditioning unit for estimating the mass flow rate of a supercritical refrigerant, based on a measurement of the high pressure and a measurement of the low pressure. However, in order for the estimate for the mass flow rate to be sufficiently accurate, it is necessary for the air conditioning circuit to be controlled so that the refrigerant leaving the expander is almost entirely in the liquid state. Moreover, a sensor is required for measuring the low pressure, which increases the cost of the air conditioning unit.
  • French patent application 03/03362 also proposes an air conditioning unit for estimating the mass flow rate of a supercritical refrigerant. To do this, the proposed air conditioning unit includes a calculating function that uses two differences in temperature relating to the gas cooler, at least one of which is based on the temperature of the refrigerant at a chosen intermediate point on the gas cooler. This intermediate point is in particular located at a distance xi from the inlet of the gas cooler that is between 5% and 35% of the total length of the gas cooler. However, this assembly requires a large number of sensors (sensors for measuring the refrigerant pressure at the inlet and outlet of the compressor, the temperature of the refrigerant at the inlet of the gas cooler, the temperature of the stream of air received by the gas cooler and the temperature of the refrigerant at the chosen intermediate point on the gas cooler), which therefore increases the cost of the assembly.
  • The subject of the present invention is an air conditioning unit that remedies these known drawbacks of the prior art.
  • For this purpose, the invention proposes a motor vehicle air conditioning unit, provided with a supercritical refrigerant circuit comprising a compressor, a gas cooler, an expander, defining a refrigerant flow area, and an evaporator. The assembly further includes an electronic control device designed to interact with the refrigerant circuit. Advantageously, the electronic control device includes a calculating function using an estimate of the flow area of the expander, the density of the refrigerant and the pressure of the refrigerant at the inlet of the expander in order to calculate an estimate of the refrigerant mass flow rate at the expander.
  • According to one aspect of the invention, the flow area of the expander is estimated from the refrigerant pressure at the inlet of the expander.
  • In particular, the electronic control device may be capable of reacting to the fact that the value of the refrigerant pressure P20 at the inlet of the expander is:
      • less than or equal to a first pressure value P1, a first constant S1 being assigned to the flow area of the expander;
      • less than or equal to a second pressure value P2 greater than the first pressure value P1, by solving the following equation in order to calculate an estimate of the flow area S of the expander:
        S=S1+(S2−S1)×(P 20 −P1)/(P2−P1),
      • where S2 is a second constant;
      • less than or equal to a third pressure value P3 and greater than the second pressure value P2, solving the following equation in order to calculate an estimate of the flow area S of the expander:
        S=S2+(S3−S2)×(P 20 −P2)/(P3−P2),
      • where S3 is a third constant; and
      • greater than or equal to the third pressure value P3, a fourth constant S4 being assigned to the flow area of the expander.
  • In one particular embodiment, the first pressure value P1 is approximately equal to 80 bar, the second pressure value P2 is approximately equal to 110 bar and the third pressure value P3 is approximately equal to 135 bar, while the first constant S1 is approximately equal to 0.07 mm2, the second constant S2 is approximately equal to 0.5 mm2, the third constant S3 is approximately equal to 0.78 mm2 and the fourth constant S4 is approximately equal to 3.14 mm2.
  • According to another aspect of the invention, the calculating function is specific to calculating the density of the refrigerant from the refrigerant temperature at the inlet of the expander and from the refrigerant pressure at the inlet of the expander.
  • The air conditioning unit may include a probe placed at the inlet of the expander for measuring the refrigerant temperature at the inlet of the expander.
  • The air conditioning unit may also include a sensor placed at the inlet of the expander for measuring the refrigerant pressure at the inlet of the expander.
  • As a complement, the electronic control device may include a power estimation function capable of estimating the power absorbed by the compressor from:
      • the refrigerant mass flow rate provided by the calculating function;
      • the work of the compressor; and
      • the rotation speed of the compressor.
  • The electronic control device is capable of estimating the work of the compressor from the refrigerant pressure at the inlet of the expander, from the refrigerant pressure at the inlet of the compressor and from a refrigerant temperature relative to the compressor.
  • Advantageously, the refrigerant pressure at the inlet of the compressor is estimated from a pressure at the inlet or at the outlet of the evaporator combined with the refrigerant mass flow rate.
  • Furthermore, the pressure at the inlet or at the outlet of the evaporator is determined from the refrigerant temperature, said temperature being either measured by a probe or estimated from:
      • a temperature relative to the evaporator;
      • the efficiency of the evaporator; and
      • the temperature of the air to be cooled.
  • The refrigerant temperature relative to the compressor may be the refrigerant temperature at the inlet of the compressor.
  • The air conditioning unit may then include a probe placed at the inlet of the compressor for measuring the refrigerant temperature at the inlet of the compressor.
  • As a variant, the refrigerant temperature relative to the compressor may be the refrigerant temperature at the outlet of the compressor.
  • The air conditioning installation may then include a probe placed at the outlet of the compressor for measuring the refrigerant temperature at the outlet of the compressor.
  • The invention also covers a product-program, which may be defined as comprising the functions used for estimating the refrigerant mass flow rate and the power consumed by the compressor.
  • Other features and advantages of the invention will become apparent on examining the detailed description below and the appended drawings in which:
  • FIG. 1A is a diagram of a motor vehicle air conditioning circuit operating with a supercritical refrigerant;
  • FIG. 1B is a diagram of an air conditioning unit according to the invention;
  • FIG. 2 is a plot showing the variations in the flow area of the expander as a function of the refrigerant pressure at the inlet of the expander;
  • FIG. 3 is a flow diagram showing the steps implemented by the control device for estimating the refrigerant mass flow rate at the expander;
  • FIG. 4 is a flow diagram showing the steps implemented by the control device for estimating the flow area of the expander;
  • FIG. 5 is a flow diagram representing the steps implemented by the control device for estimating the power consumed by the compressor, according to the invention;
  • FIGS. 6 and 7 are diagrams of the air conditioning circuit according to alternative embodiments of the invention;
  • FIGS. 8 to 12 are schematic diagrams showing the position of the temperature probes used for determining the pressure at the inlet or at the outlet of the evaporator;
  • FIG. 13 illustrates the method of determining the pressure of the refrigerant at the inlet of the compressor; and
  • FIG. 14 shows the relationship between the refrigerant mass flow rate and the refrigerant pressure at the inlet of the compressor.
  • Appendix A comprises the main mathematical equations used for implementing the assembly.
  • The drawings essentially contain elements having a certain character. They therefore serve not only for making the description more clearly understood but also for contributing to the definition of the invention, where appropriate.
  • FIG. 1A represents an air conditioning circuit through which a supercritical refrigerant flows. Hereafter, the description will refer to the supercritical refrigerant CO2 as a nonlimiting example.
  • Such a circuit conventionally comprises:
      • a compressor 14 suitable for receiving the refrigerant in the gaseous state and compressing it;
      • a gas cooler 11 suitable for cooling the gas compressed by the compressor;
      • an expander 12 suitable for lowering the pressure of the refrigerant; and
      • an evaporator 13 suitable for making the refrigerant from the expander pass from the liquid state to the gaseous state in order to produce a stream of conditioned air 21 that is sent into the passenger compartment of the vehicle.
  • The circuit may further include an internal heat exchanger 23, allowing the refrigerant flowing from the gas cooler to the expander to give up heat to the refrigerant flowing from the evaporator to the compressor. The circuit may further include an accumulator 17 placed between the outlet of the evaporator and the inlet of the compressor, in order to avoid liquid surges.
  • The gas cooler 11 receives a stream of external air 16 for extracting the heat taken from the passenger compartment, which stream under certain operating conditions is blown by a motor/fan unit 15.
  • The evaporator 13 receives a stream of air from a blower, in order to produce a stream of conditioned air 21.
  • The expander 12 may have a variable flow area, such as an electronic expander, a thermostatic expander or any other expander for which the flow area depends on the high pressure. The expander 12 may also have a fixed flow area, such as a calibrated orifice.
  • The supercritical refrigerant is compressed in the gaseous phase and raised to a high pressure by the compressor 14. The gas cooler 11 then cools the refrigerant by means of the incoming stream of air 16. Unlike the air conditioning circuits operating with a subcritical refrigerant, the cooling of the refrigerant after compression does not involve a phase change. The refrigerant passes to the two-phase state, with a vapor content that depends on the low pressure, only during the expansion. The internal heat exchanger 23 allows the refrigerant to be very strongly cooled.
  • Referring now to FIG. 1B, this shows an air conditioning unit according to the invention installed in a motor vehicle.
  • The motor vehicle is driven by an engine 43, which may be controlled by a fuel injection computer 42. The fuel injection computer 42 receives information from various sensors, which it interprets in order to adjust the injection parameters.
  • The fuel injection computer 42 may also provide information about the conditions inside or outside the vehicle (information provided by a solar sensor, number of occupants, etc.). In particular, it may provide information about instantaneous values relating to the operation of the vehicle, and especially about the rotational speed N of the compressor.
  • The unit is also provided with an air conditioning computer 40, comprising a passenger compartment regulator 41 and an air conditioning loop regulator 402. The passenger compartment regulator 41 is designed to set the temperature setpoint of the external air blown into the evaporator 13.
  • The engine fuel injection computer may act on the air conditioning unit via an air conditioning regulator 402. This link may prevent the operation of the air conditioning unit when the engine is on high load.
  • The air conditioning unit according to the invention is based on a model of the expander, in order to provide an estimate of the refrigerant mass flow rate mexp at the expander.
  • The air conditioning unit includes an electronic control device, for example an electronic card 401, designed to interact with the air conditioning circuit 10 via the links 30/31 and with the fuel injection computer 42 via the links 32/33.
  • The electronic card 401 may be considered as an integral part of the vehicle air conditioning computer 40.
  • The electronic card 401 may receive information 30 coming from sensors fitted on the air conditioning circuit 10. It may also receive information from the engine fuel injection computer 42 via the link 33, in particular the rotation speed N of the compressor and/or the run speed V of the vehicle.
  • The Applicant has found that the expander may be modelled by equation A10 of Appendix A, where K is a coefficient that characterizes the expander, in particular its pressure drop.
  • From this model, the calculating function can calculate an estimate of the refrigerant mass flow rate mexp at the expander from:
      • the pressure P20 of the refrigerant at the inlet of the expander;
      • the density ρ of the CO2 refrigerant; and
      • the flow area S (in mm2) of the expander.
  • The Applicant has also found that the density ρ of the CO2 refrigerant may be estimated from the temperature T30 at the inlet of the expander and from the pressure P20 at the inlet of the expander, according to equation A11 of Appendix A.
  • The Applicant has furthermore found that the flow area S (in mm2) of an expander with a flow area depends on the refrigerant pressure P20 at the inlet of the expander.
  • Thus, an estimate of the refrigerant mass flow rate mexp at the expander may be obtained from the refrigerant pressure P20 at the inlet of the expander and from the temperature T30 at the inlet of the expander.
  • The refrigerant pressure P20 at the inlet of the expander and the refrigerant temperature T30 at the inlet of the expander may be estimated or measured.
  • The air conditioning circuit may include two separate sensors for measuring the refrigerant pressure P20 at the inlet of the expander and the refrigerant temperature T30 at the inlet of the expander, respectively. As a variant, the air conditioning circuit may have a single sensor placed at the inlet of the expander for measuring both these quantities.
  • FIG. 2 is a plot showing the variation in the flow area S (in mm2) as a function of the refrigerant pressure P20 (in bar) at the inlet of the expander. The curves shown on this plot correspond to equations A2 to A5 of Appendix A.
  • As long as the refrigerant pressure P20 at the inlet of the expander is less than or equal to a first pressure value P1, the area S is equal to a first constant S1 according to equation A2 of Appendix A.
  • When the pressure P20 is above the first pressure value P1 and less than or equal to a second pressure value P2, the area S follows a straight line whose directrix is determined from the values of S1, P1, P2 and a second constant S2, in accordance with equation A3 of Appendix A. The value of S2 corresponds to the value of the area S when P20 is equal to the valave P2.
  • When the pressure P20 is greater than the second pressure value P2 and less than or equal to a third pressure value P3, the area S follows a straight line whose directrix is determined from the values of S2, P2, P3 and a third constant S3 in accordance with equation A4 of Appendix A.
  • When the pressure P20 is greater than or equal to the third pressure value P3, the area S is equal to a fourth constant S4 greater than the third constant S3 in accordance with equation A5 of Appendix A.
  • In particular, the first pressure value P1 may be approximately equal to 80 bar, the second pressure value P2 may be approximately equal to 110 bar, the third pressure value P3 may be approximately equal to 135 bar, the first constant S1 may be approximately equal to 0.07 mm2, the second constant S2 may be approximately equal to 0.5 mm2, the third constant S3 may be approximately equal to 0.78 mm2 and the fourth constant S4 may be approximately equal to 3.14 mm2.
  • As a complement, the estimate of the refrigerant mass flow rate, provided by the calculating function of the electronic card, may be used to calculate the mechanical power absorbed. To do this, the electronic card includes a power estimation function capable of estimating the power Pabs absorbed by the compressor from the refrigerant mass flow rate mexp. In particular, the power estimation function is capable of estimating the power Pabs absorbed by the compressor from the isentropic work of compression Wise and from the rotation speed N of the compressor in accordance with equation A6 of Appendix A. The coefficients a and b are related to operating parameters of the air conditioning circuit. The coefficient a corresponds to the mechanical efficiency relative to the isentropic compression of the compressor and is around 1.38. The coefficient b is the image of the compressor efficiency and corresponds to the friction factor of the compressor.
  • In accordance with equation A7 of Appendix A, the isentropic compression power Wise is related:
      • to the refrigerant mass flow rate mexp, an estimate of which is calculated by the calculating function as described above; and
      • to the isentropic work ΔHise of the compressor.
  • The Applicant has found that the estimate of the work ΔHise of the compressor may be obtained, in accordance with equation A80 of Appendix A, from:
      • the refrigerant pressure P20 at the inlet of the expander;
      • the refrigerant pressure P35 at the inlet of the compressor; and
      • the temperature of the refrigerant Tcomp relative to the compressor.
  • The refrigerant pressure P35 at the inlet of the compressor and the temperature of the refrigerant Tcomp relative to the compressor may be estimated or measured.
  • The pressure of the refrigerant at the inlet of the compressor is estimated using the refrigerant mass flow rate mexp calculated above and from the pressure drop Δp between the inlet of the evaporator 13 and the inlet of the compressor 14.
  • As a variant, this estimate of the refrigerant pressure at the inlet of the compressor may be determined using the refrigerant mass flow rate mexp calculated above and from the pressure drop Δp between the outlet of the evaporator 13 and the inlet of the compressor 14.
  • The example below is described in relation to the inlet pressure of the evaporator 13, but this example can be transposed in a similar manner using the pressure at the outlet of the evaporator 13.
  • This pressure drop Δp is calculated from formula A90 of Appendix A, in which:
      • P50 is an estimate of the pressure at the inlet of the evaporator;
      • P35 is the estimate of the refrigerant pressure at the inlet of the compressor.
  • It is also known that this pressure drop Δp may be determined from formula A100 in which:
      • K is a pressure drop coefficient;
      • ρ is the density of the refrigerant; and
      • Vco 2 is the speed of the refrigerant.
  • In accordance with equation A101 of Appendix A, the speed of the refrigerant Vco 2 can be determined from:
      • the refrigerant mass flow rate mexp determined by means of equation A10;
      • the refrigerant density ρ; and
      • a constant S corresponding to the mean flow area and mean flow length, combining both the linear pressure drop and the singular pressure drop, experienced by the refrigerant. From the two equations A90 and A100 it is possible to estimate the pressure of the refrigerant at the inlet of the compressor, as illustrated by equation A9.
  • Thus, the only unknown in this equation is the estimate of the pressure P50 at the inlet of the evaporator.
  • It is known from the fluids saturation law, otherwise known as the fluid state law, that the pressure P50 at the inlet of the evaporator depends directly on the saturation temperature T50 at the inlet of the evaporator. Over the operating range of interest to us, this equation may be represented in the form of a second-order polynomial.
  • This saturation temperature T50 of the pressure refrigerant may be measured or estimated.
  • When it is estimated, equation A91 of Appendix A is used, in which:
      • T40 is a datum relating to the evaporator temperature available on many air conditioning units. This involves a CTN or CTP probe placed on the evaporator, the main objective of which in the prior art is to prevent the evaporator from icing up when the compressor stops. This temperature T40 corresponds to the surface temperature of one of the walls of the evaporator 13 (for example at the recess of the inserts, as illustrated in FIG. 12) or to the air temperature at the outlet of the evaporator;
      • ηevap is the image of the evaporator efficiency, which can be easily related to a function of the voltage U for the air blower of the evaporator in the passenger compartment and the run speed V of the vehicle, as expressed in equation A910 of Appendix A; and
      • T60 is the temperature of the air to be cooled by the air conditioning unit. This temperature is estimated according to the temperature inside the passenger compartment, the temperature outside the passenger compartment, the voltage U for the blower, the position of the recycling flap of the air conditioning unit and the run speed V of the vehicle. This function is expressed in equation A920 of Appendix A.
  • FIGS. 8 and 9 illustrate the possibility of measuring the saturation temperature T50 of the refrigerant at the inlet of the evaporator 13 either by means of an intrusive or direct temperature probe 51, that is to say a probe directly bathed by the refrigerant (FIG. 7), or by a nonintrusive or indirect probe 52, which measures the temperature of the refrigerant on the basis of the temperature of the tube that is transporting it (FIG. 8).
  • FIGS. 10 and 11 show the possibility of measuring the saturation temperature T50 of the refrigerant at the outlet of the evaporator 13 using means identical to the temperature measurement envisaged at the inlet of the evaporator 13.
  • This method of determining the refrigerant pressure at the inlet of the compressor is summarized in FIG. 13 in the form of a block diagram in which:
      • if the temperature T50 at the inlet or at the outlet of the evaporator is estimated, then the following are used:
        • the evaporator efficiency ηevap determined from the information available about the vehicle, such as blower voltage U and the run speed V of the vehicle,
        • these two items of information are used also to determine the temperature T60 of the air to be cooled, combined with the temperature inside the passenger compartment and the external temperature and
        • the evaporator efficiency ηevap, the temperature T60 of the air to be cooled and the surface temperature T40 of the evaporator are combined to estimate the temperature T50 at the inlet of the evaporator 13;
      • if the temperature T50 is measured, a temperature probe 51 or 52 delivers the expected value;
      • the estimated or measured temperature T50 is used to determine the pressure P50 according to the refrigerant saturation law;
      • this pressure P50 at the inlet or the outlet of the evaporator 13, combined with the refrigerant pressure P20 at the inlet of the expander, with the density ρ of the CO2 refrigerant and the flow area S (in mm2) of the expander allows the refrigerant mass flow rate to be determined; and
      • finally, the combination of this mass flow rate information with the estimate of the pressure P50 at the inlet of the evaporator allows the refrigerant pressure P35 at the inlet of the compressor to be determined without using a specific sensor and thus without increasing the cost of the air conditioning unit.
  • FIG. 14 illustrates the relationship between the refrigerant mass flow rate and the refrigerant pressure P35 at the inlet of the compressor. The x-axis of this curve represents the mass flow rate mexp in kilograms per hour and the y-axis of this curve illustrates the pressure drop Δp in bar between the inlet or the outlet of the evaporator 13 and the inlet of the compressor 14. It may be seen that an error of around 30 kg in the estimate of the mass flow rate results in an error of around 2 bar in the determination of P35. This error is minor compared with the absolute operating pressure values, which are often greater than 35 bar.
  • The refrigerant temperature relative to the compressor may be the refrigerant temperature T35 at the inlet of the compressor, in accordance with equation A81 of Appendix A. R is the perfect gas constant and M corresponds to the molar mass of the refrigerant. The ratio R/M may especially be equal to 188.7.
  • As a variant, the refrigerant temperature relative to the compressor may be the refrigerant temperature T36 at the outlet of the compressor in accordance with equation A82 of Appendix A.
  • FIG. 3 is a flow diagram showing the steps implemented by the electronic card for estimating the refrigerant mass flow rate mexp and the power consumed by the compressor.
  • At step 100, the refrigerant pressure P20 at the inlet of the expander is estimated/measured. Referring to FIGS. 1B, 6 and 7, the refrigerant pressure P20 at the inlet of the expander may be measured by a sensor 20 placed at the inlet of the expander. As a variant, the pressure P20 of the refrigerant at the inlet of the expander may be estimated.
  • At step 102, the electronic card 401 estimates the flow area S of the expander 12 from the measured/estimated refrigerant pressure value P20 at the inlet of the expander in accordance with equations A4 and A5 of Appendix A.
  • Step 102 is shown in detail in the flow diagram of FIG. 4. The electronic card determines if the measured value of the refrigerant pressure P20 at the inlet of the expander is:
      • less than or equal to the first pressure value P1 (step 1020), in which case the flow area of the expander is equal to S1;
      • greater than the first constant P1 and less than or equal to the second pressure value P2 (step 1021), in which case the flow area of the expander is given by equation A3 of Appendix A as a function of the pressure P20 obtained at step 100;
      • greater than the second pressure value P2 and less than or equal to the third pressure value P3 (step 1022), in which case the flow area of the expander is given by equation A4 of Appendix A, as a function of the pressure P20 obtained at step 100; and
      • greater than or equal to the third pressure value P3 (step 1023), in which case the flow area of the expander is equal to S4.
  • At step 103, the electronic card provides an estimate/measurement of the temperature T30 at the inlet of the expander. The unit may include a temperature sensor 30 for measuring the refrigerant temperature T30 at the inlet of the expander, as shown in FIGS. 1B, 6 and 7. As a variant, the unit may include a single sensor 20 for measuring both the pressure P20 and the temperature T30 of the refrigerant at the inlet of the expander. The refrigerant temperature T30 at the inlet of the expander may also be estimated.
  • At step 104, the electronic card 401 estimates the density ρ of the CO2 refrigerant. The density ρ of the CO2 refrigerant may be calculated according to equation A11 of Appendix A from the refrigerant pressure P20 at the inlet of the expander, obtained at step 100, and from the refrigerant temperature T30 at the inlet of the expander, obtained at step 103.
  • At step 105 of FIG. 3, the electronic card 401 can then calculate the refrigerant mass flow rate mexp according to equation A3 of Appendix A, from:
      • the refrigerant pressure P20 at the inlet of the expander, estimated/measured at step 100;
      • the flow area S (in mm2) of the expander, estimated at step 102; and
      • the density ρ of the CO2 refrigerant, estimated at step 104.
  • As a complement, the estimate of the refrigerant mass flow rate mexp at the expander may be used to calculate the power Pabs consumed by the compressor.
  • FIG. 5 is a flow diagram showing the steps implemented by the electronic card for calculating the power Pabs consumed by the compressor from the estimate of the refrigerant mass flow rate mexp at the expander. The estimate of the power absorbed by the compressor may in particular require a prior estimate of the work ΔHise of the compressor, in accordance with equations A6 and A7 of Appendix A.
  • At step 200, the electronic card calculates an estimate of the work ΔHise of the compressor in accordance with equation A8 of Appendix A from:
      • the refrigerant pressure P20 at the inlet of the expander;
      • the refrigerant pressure P35 at the inlet of the compressor; and
      • the refrigerant temperature Tcomp relative to the compressor.
  • When the refrigerant temperature relative to the compressor is the refrigerant temperature T35 at the inlet of the compressor (in accordance with equation A81 of Appendix A), it can be measured by a probe 35 placed at the inlet of the compressor, as shown in FIGS. 1B and 6.
  • When the refrigerant temperature relative to the compressor is the refrigerant temperature T36 at the outlet of the compressor (in accordance with equation A82 of Appendix A), it can be measured by a probe 36 placed at the outlet of the compressor, as shown in FIG. 7.
  • The refrigerant pressure P12 at the inlet of the compressor may be estimated or measured.
  • At step 202, the electronic card calculates the isentropic power Wise from the refrigerant mass flow rate mexp obtained at step 105 and the work ΔHise of the compressor obtained at step 200, in accordance with equation A7 of Appendix A.
  • At step 204, the electronic card calculates an estimate of the power Pabs absorbed by the compressor, according to equation A6 of Appendix A, from the isentropic power Wise obtained at step 202 and the rotation speed N of the compressor.
  • The rotation speed N of the compressor is supplied to the electronic card by the engine fuel injection computer 42 via the link 33, with reference to FIG. 1B.
  • The computer may use the estimated value of the actual power consumed by the compressor to adjust the injection parameters, thereby making it possible to reduce the fuel consumption.
  • The air conditioning unit according to the invention makes it possible to obtain a satisfactory estimate of the refrigerant mass flow rate at the expander. Furthermore, this unit does not use a low-pressure sensor to estimate the refrigerant mass flow rate at the expander, thereby allowing the total cost of the unit to be reduced.
  • Of course, the present invention is not limited to the embodiments described above. It encompasses all alternative embodiments that a person skilled in the art might envision.
  • The present invention also covers the software code that it uses, most particularly when this is available on any medium that can be read by a computer. The expression “medium that can be read by a computer” covers a storage medium, for example a magnetic or optical storage medium, and also a transmission means, such as a digital or analog signal.
  • APPENDIX A
  • Supercritical Refrigerant Mass Flow Rate
    m exp =KSρ ln(P 20 +C)   (A10)
    ρ=f(T 30 , P 20)   (A11)
  • Flow Area S of the Expander
  • IF P20≦P1:
    S=S1   (A2)
  • If P1<P20≦P2:
    S=S1+(S2−S1)(P 20 −P1)/(P2−P1)   (A3)
  • If P2<P20≦P3:
    S=S2+(S3−S2)/(P 20 −P2)/(P3−P2)   (A4)
  • If P20≧P3:
    S=S4   (A5)
  • Power Consumed by the Compressor
    P abs =aW ise +bN   (A6)
  • Isentropic Power Wise
    Wise=mexpΔHise   (A7)
  • Work ΔHise of the Compressor
    ΔH ise =f(P 20 , P 35 , T 35)   (A80)
    ΔH ise=[(P 20 /P 35)(k−1)/k−1](T 35+273.15)(R/M)/(k−1)   (A81)
    ΔH ise=[1−(P 20 /P 35)(1−k)/k](T 36+273.15)(R/M)/(k−1)   (A82)
  • Estimate of the Refrigerant Pressure P35 at the Inlet of the Compressor
    Δp=P 50 −P 35   (A90)
    Δp=k ρvCo 2/2   (A100)
    Vco 2 =M exp/(ρS)   (A101)
    P 36 =P 50 −M exp K(2ρS 2)   (A9)
    T 60=(T 40−(1−ηevap)T 60)/ηevap   (A91)
    T50=>P60 R744 refrigerant saturation law

Claims (15)

1. A motor vehicle air conditioning unit, provided with a supercritical refrigerant circuit (10) comprising a compressor (14), a gas cooler (11), an expander (12), defining a refrigerant flow area, and an evaporator (13), the assembly further including an electronic control device designed to interact with the refrigerant circuit,
characterized in that the electronic control device includes a calculating function using an estimate of the flow area of the expander, the density (ρ) of the refrigerant and the pressure (P20) of the refrigerant at the inlet of the expander in order to calculate an estimate of the refrigerant mass flow rate (mexp) at the expander.
2. The air conditioning unit as claimed in claim 1, characterized in that the flow area of the expander is estimated from the value of the refrigerant pressure (P20) at the inlet of the expander.
3. The air conditioning unit as claimed in claim 2, characterized in that the electronic control device is capable of reacting to the fact that the value of the refrigerant pressure P20 at the inlet of the expander is:
less than or equal to a first pressure value P1, a first constant S1 being assigned to the flow area S of the expander;
less than or equal to a second pressure value P2 greater than the first pressure value P1, by solving the following equation in order to calculate an estimate of the flow area S of the expander:

S=S1+(S2−S1)×(P 20 −P1)/(P2−P1),
where S2 is a second constant;
less than or equal to a third pressure value P3
less than or equal to a third pressure value P3 and greater than the second pressure value P2, solving the following equation in order to calculate an estimate of the flow area S of the expander:

S=S2+(S3−S2)×(P 20 −P2)/(P3−P2),
where S3 is a third constant; and
greater than or equal to the third pressure value P3, a fourth constant S4 being assigned to the flow area of the expander.
4. The air conditioning unit as claimed in claim 3, characterized in that the first pressure value P1 is approximately equal to 80 bar, the second pressure value P2 is approximately equal to 110 bar and the third pressure value P3 is approximately equal to 135 bar and in that the first constant S1 is approximately equal to 0.07 mm2, the second constant S2 is approximately equal to 0.5 mm2, the third constant S3 is approximately equal to 0.78 mm2 and the fourth constant S4 is approximately equal to 3.14 mm2.
5. The air conditioning unit as claimed in one of the preceding claims, characterized in that the calculating function is specific to calculating the density (ρ) of the refrigerant from the refrigerant temperature (T30) at the inlet of the expander and from the refrigerant pressure (P20) at the inlet of the expander.
6. The air conditioning unit as claimed in claim 5, characterized in that it includes a probe (30) placed at the inlet of the expander (12) for measuring the refrigerant temperature (T30) at the inlet of the expander.
7. The air conditioning unit as claimed in one of the preceding claims, characterized in that it includes a sensor (20) placed at the inlet of the expander (12) for measuring the refrigerant pressure (P20) at the inlet of the expander.
8. The air conditioning unit as claimed in one of the preceding claims, characterized in that the electronic control device further includes a power estimation function capable of estimating the power absorbed by the compressor from:
the refrigerant mass flow rate (mexp) provided by the calculating function;
the work (ΔHise) of the compressor; and
the rotation speed (N) of the compressor.
9. The air conditioning unit as claimed in claim 8, characterized in that the electronic control device is capable of estimating the work (ΔHise) of the compressor from the refrigerant pressure (P20) at the inlet of the expander, from the refrigerant pressure (P35) at the inlet of the compressor and from a refrigerant temperature (Tcomp) relative to the compressor.
10. The air conditioning unit as claimed in claim 9, characterized in that the refrigerant pressure (P35) at the inlet of the compressor is estimated from a pressure (P50) at the inlet or at the outlet of the evaporator (13) combined with the refrigerant mass flow rate (mexp).
11. The air conditioning unit as claimed in claim 10, characterized in that the pressure (P50) at the inlet or at the outlet of the evaporator (13) is determined from the refrigerant temperature (T50) at the inlet or at the outlet of the evaporator (13), said temperature being either measured by a probe or estimated from:
a temperature (T40) relative to the evaporator (13);
the efficiency (ηevap) of the evaporator (13); and
the temperature (T60) of the air to be cooled.
12. The air conditioning unit as claimed in one of claims 9 to 11, characterized in that the refrigerant temperature relative to the compressor (10) is the refrigerant temperature (T35) at the inlet of the compressor.
13. The air conditioning unit as claimed in claim 12, characterized in that it includes a probe (35) placed at the inlet of the compressor (14) for measuring the refrigerant temperature (T35) at the inlet of the compressor.
14. The air conditioning unit as claimed in one of claims 9 to 11, characterized in that the refrigerant temperature relative to the compressor (14) is the refrigerant temperature (T36) at the outlet of the compressor.
15. The air conditioning unit as claimed in claim 14, characterized in that it includes a probe (36) placed at the outlet of the compressor (14) for measuring the refrigerant temperature (T36) at the outlet of the compressor.
US10/578,462 2003-11-25 2004-11-17 Air-Conditioning Assembly Abandoned US20070095085A1 (en)

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FR03/13823 2003-11-25
FR0313823A FR2862573B1 (en) 2003-11-25 2003-11-25 AIR CONDITIONING INSTALLATION OF VEHICLE
PCT/IB2004/003769 WO2005051691A1 (en) 2003-11-25 2004-11-17 Vehicle air-conditioning assembly

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EP (1) EP1687161B1 (en)
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AT (1) ATE358602T1 (en)
DE (1) DE602004005745T2 (en)
ES (1) ES2285547T3 (en)
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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070028633A1 (en) * 2005-08-05 2007-02-08 Kenichi Suzuki Air Conditioning Systems For Vehicles
US20090272128A1 (en) * 2008-05-02 2009-11-05 Kysor Industrial Corporation Cascade cooling system with intercycle cooling
WO2018095785A1 (en) * 2016-11-22 2018-05-31 Danfoss A/S A method for handling fault mitigation in a vapour compression system
US10962262B2 (en) 2016-11-22 2021-03-30 Danfoss A/S Method for controlling a vapour compression system during gas bypass valve malfunction

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2913102B1 (en) * 2007-02-28 2012-11-16 Valeo Systemes Thermiques AIR CONDITIONING INSTALLATION EQUIPPED WITH AN ELECTRICAL RELIEF VALVE
JP4375437B2 (en) * 2007-05-28 2009-12-02 株式会社デンソー Compressor suction pressure estimation device for refrigeration cycle equipment
JP4380730B2 (en) * 2007-05-28 2009-12-09 株式会社デンソー Compressor suction pressure estimation device for refrigeration cycle equipment
FR2932262B1 (en) * 2008-06-09 2010-07-30 Valeo Systemes Thermiques METHOD FOR ESTIMATING THE POWER ABSORBED BY A COMPRESSOR AT STARTING AN AIR CONDITIONING FACILITY
JP2011031679A (en) * 2009-07-30 2011-02-17 Sanden Corp Air conditioner for vehicle
DE102022118623A1 (en) 2022-07-26 2024-02-01 Audi Aktiengesellschaft Method for operating a refrigeration system with supercritical refrigerant, refrigeration system and motor vehicle with refrigeration system

Citations (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1349409A (en) * 1918-09-07 1920-08-10 Vergne Machine Company De Method and apparatus for measuring the capacity of refrigerating plants
US4977529A (en) * 1973-02-23 1990-12-11 Westinghouse Electric Corp. Training simulator for a nuclear power plant
US5224354A (en) * 1991-10-18 1993-07-06 Hitachi, Ltd. Control system for refrigerating apparatus
US5402652A (en) * 1984-08-08 1995-04-04 Alsenz; Richard H. Apparatus for monitoring solenoid expansion valve flow rates
US5677677A (en) * 1995-04-21 1997-10-14 Carrier Corporation System for monitoring the operation of an evaporator unit
US6339933B2 (en) * 1999-12-20 2002-01-22 Valeo Climatisation Device for air conditioning a motor-vehicle passenger compartment, with improved ventilation control
US20020023451A1 (en) * 2000-08-28 2002-02-28 Yasutaka Kuroda Vehicle air conditioner with refrigerant flow-amount control of compressor
US20020116932A1 (en) * 1997-05-30 2002-08-29 Renders Marie Joseph Method and device for testing and diagnosing an automotive air conditioning system
US20030005710A1 (en) * 2001-05-03 2003-01-09 Abtar Singh Method of managing a refrigeration system
US20030159452A1 (en) * 2000-10-12 2003-08-28 Mohamed Ben Yahia Vehicle air conditioning device using a supercritical cycle
US20040060310A1 (en) * 2002-09-27 2004-04-01 Valeo Climatisation S.A. Air conditioning system comprising an electronic control device
US20050172652A1 (en) * 2001-12-20 2005-08-11 Mohamed Ben Yahia Motor vehicle air-conditioning installation equipped with an electronic control device

Family Cites Families (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1158A (en) 1839-05-25 Improvement in cotton-gins for cleaning cotton
JPS6115057A (en) * 1984-07-02 1986-01-23 株式会社日立製作所 Measuring device for flow rate of refrigerant of refrigeration cycle
JPS6373059A (en) * 1986-09-13 1988-04-02 ダイキン工業株式会社 Refrigerator
EP0324223B1 (en) * 1987-11-06 1996-01-17 Dataproducts Corporation Method and apparatus for improving print characteristics
JPH01148614A (en) * 1987-12-04 1989-06-12 Diesel Kiki Co Ltd Air-cooling device for automobile
NO175830C (en) * 1992-12-11 1994-12-14 Sinvent As Kompresjonskjölesystem
JPH08219591A (en) * 1995-02-15 1996-08-30 Mitsubishi Heavy Ind Ltd Throttling apparatus for refrigerating cycle
DE19935731A1 (en) * 1999-07-29 2001-02-15 Daimler Chrysler Ag Operating method for automobile refrigeration unit has cooling medium mass flow regulated by compressor and cooling medium pressure determined by expansion valve for regulation within safety limits
JP2001174076A (en) * 1999-10-08 2001-06-29 Zexel Valeo Climate Control Corp Refrigeration cycle
JP2002139259A (en) * 2000-10-31 2002-05-17 Zexel Valeo Climate Control Corp Refrigerating cycle controller
US6817193B2 (en) * 2001-11-23 2004-11-16 Daimlerchrysler Ag Method for operating a refrigerant circuit, method for operating a motor vehicle driving engine, and refrigerant circuit
JP3936200B2 (en) * 2002-01-25 2007-06-27 サンデン株式会社 Air conditioner for vehicles
JP4119143B2 (en) * 2002-03-22 2008-07-16 カルソニックカンセイ株式会社 Driving torque calculation device for variable displacement compressor

Patent Citations (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1349409A (en) * 1918-09-07 1920-08-10 Vergne Machine Company De Method and apparatus for measuring the capacity of refrigerating plants
US4977529A (en) * 1973-02-23 1990-12-11 Westinghouse Electric Corp. Training simulator for a nuclear power plant
US5402652A (en) * 1984-08-08 1995-04-04 Alsenz; Richard H. Apparatus for monitoring solenoid expansion valve flow rates
US5224354A (en) * 1991-10-18 1993-07-06 Hitachi, Ltd. Control system for refrigerating apparatus
US5677677A (en) * 1995-04-21 1997-10-14 Carrier Corporation System for monitoring the operation of an evaporator unit
US20020116932A1 (en) * 1997-05-30 2002-08-29 Renders Marie Joseph Method and device for testing and diagnosing an automotive air conditioning system
US6339933B2 (en) * 1999-12-20 2002-01-22 Valeo Climatisation Device for air conditioning a motor-vehicle passenger compartment, with improved ventilation control
US20020023451A1 (en) * 2000-08-28 2002-02-28 Yasutaka Kuroda Vehicle air conditioner with refrigerant flow-amount control of compressor
US20030159452A1 (en) * 2000-10-12 2003-08-28 Mohamed Ben Yahia Vehicle air conditioning device using a supercritical cycle
US20030005710A1 (en) * 2001-05-03 2003-01-09 Abtar Singh Method of managing a refrigeration system
US20050172652A1 (en) * 2001-12-20 2005-08-11 Mohamed Ben Yahia Motor vehicle air-conditioning installation equipped with an electronic control device
US20040060310A1 (en) * 2002-09-27 2004-04-01 Valeo Climatisation S.A. Air conditioning system comprising an electronic control device

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070028633A1 (en) * 2005-08-05 2007-02-08 Kenichi Suzuki Air Conditioning Systems For Vehicles
US20090272128A1 (en) * 2008-05-02 2009-11-05 Kysor Industrial Corporation Cascade cooling system with intercycle cooling
US9989280B2 (en) 2008-05-02 2018-06-05 Heatcraft Refrigeration Products Llc Cascade cooling system with intercycle cooling or additional vapor condensation cycle
WO2018095785A1 (en) * 2016-11-22 2018-05-31 Danfoss A/S A method for handling fault mitigation in a vapour compression system
US10962262B2 (en) 2016-11-22 2021-03-30 Danfoss A/S Method for controlling a vapour compression system during gas bypass valve malfunction
US11340000B2 (en) 2016-11-22 2022-05-24 Danfoss A/S Method for handling fault mitigation in a vapour compression system

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ATE358602T1 (en) 2007-04-15
JP2007512179A (en) 2007-05-17
DE602004005745T2 (en) 2007-12-27
EP1687161B1 (en) 2007-04-04
ES2285547T3 (en) 2007-11-16
FR2862573B1 (en) 2006-01-13
DE602004005745D1 (en) 2007-05-16
WO2005051691A1 (en) 2005-06-09
FR2862573A1 (en) 2005-05-27
JP4949036B2 (en) 2012-06-06

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