Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B49/00—Arrangement or mounting of control or safety devices
  • F25B49/02—Arrangement or mounting of control or safety devices for compression type machines, plants or systems
  • F25B49/022—Compressor control arrangements
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B40/00—Subcoolers, desuperheaters or superheaters
  • F25B40/02—Subcoolers
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B40/00—Subcoolers, desuperheaters or superheaters
  • F25B40/06—Superheaters
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B49/00—Arrangement or mounting of control or safety devices
  • F25B49/02—Arrangement or mounting of control or safety devices for compression type machines, plants or systems
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B2600/00—Control issues
  • F25B2600/21—Refrigerant outlet evaporator temperature
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B2600/00—Control issues
  • F25B2600/25—Control of valves
  • F25B2600/2513—Expansion valves
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
  • F25B2700/19—Pressures
  • F25B2700/193—Pressures of the compressor
  • F25B2700/1931—Discharge pressures
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
  • F25B2700/19—Pressures
  • F25B2700/193—Pressures of the compressor
  • F25B2700/1933—Suction pressures
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
  • F25B2700/21—Temperatures
  • F25B2700/2106—Temperatures of fresh outdoor air
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
  • F25B2700/21—Temperatures
  • F25B2700/2115—Temperatures of a compressor or the drive means therefor
  • F25B2700/21151—Temperatures of a compressor or the drive means therefor at the suction side of the compressor
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
  • F25B2700/21—Temperatures
  • F25B2700/2117—Temperatures of an evaporator
  • F25B2700/21171—Temperatures of an evaporator of the fluid cooled by the evaporator
  • F25B2700/21173—Temperatures of an evaporator of the fluid cooled by the evaporator at the outlet

Definitions

• the invention relates to the field of motor vehicles and more particularly to a motor vehicle air conditioning system and its management method in cooling mode.
• a refrigerant fluid passes successively in a compressor, a first heat exchanger, called a condenser, placed in contact with a flow of air outside the motor vehicle to release heat, an expansion device and a second heat exchanger, called evaporator, placed in contact with an interior air flow of the motor vehicle to cool it.
• the expansion device is a thermostatic valve whose bulb is disposed downstream of the evaporator.
• the expansion device can also be an electronic expansion valve controlled by a central control unit.
• This overheating is particularly useful for improving the coefficient of performance of the air conditioning circuit, but also to reduce the risk of refrigerant fluid in the liquid state passes into the compressor.
• One of the aims of the present invention is therefore to at least partially overcome the disadvantages of the prior art and to provide a method for managing an improved inverter cooling circuit, particularly in cooling mode.
• the present invention therefore relates to a method for managing an air conditioning circuit inside which a cooling fluid circulates in a cooling mode, the refrigerant flowing successively in:
• An evaporator for recovering heat energy from a second heat transfer fluid and transferring it to the cooling fluid
• said air conditioning circuit comprising a central control unit able to control the opening of the expansion device
• said method comprising:
• SHcomp_in_sp_min and a maximum superheat SHcomp_in_sp_max SHcomp_in_sp_min and a maximum superheat SHcomp_in_sp_max, SHcomp_in_sp_min and SHcomp_in_sp_max being determined as a function of the temperature Text of the first heat transfer fluid before passing through the condenser, the flow rate of the second heat transfer medium through the evaporator and the temperature of the second heat transfer fluid before its passage through the evaporator,
• a step of opening the expansion device according to Cestim and superheating control SHcomp_in by varying the opening of the expansion device so as to achieve the set superheat SHcomp_in_sp and maintain SHcomp_in between SHcomp_in_sp_min and SHcomp_in_sp_max.
• SHcomp_in is calculated according to the following formula
• Tcomp_in is the refrigerant temperature at the inlet of the compressor
• Tsat (Pcomp_in) is the saturation temperature of the refrigerant at the pressure Pcomp_in at the compressor inlet.
• the calculation of the Cestim opening of the expansion device is carried out according to one of the following formulas:
• Tevapo is the temperature of the second heat transfer fluid at the outlet of the evaporator
• Tevapo_sp is a set temperature of the second heat transfer fluid at the outlet of the evaporator
• Tsat (Pcomp_out) is the saturation temperature of the coolant at the pressure Pcomp_out of the refrigerant at the outlet of the compressor
• Text is the temperature of the first heat transfer fluid before passing through the condenser
• Pcomp_in is the refrigerant pressure at the inlet of the compressor
• Psat (Tevapo_sp) is the saturation pressure of the refrigerant at the setpoint temperature Tevapo of the second heat transfer fluid at the outlet of the evaporator
• KI being the average slope AC 'ATevapo with AC being the variation of the opening of the expansion device and ATevapo the variation of Tevapo measured during experimentation where the opening of the expansion device is varied for a regime of given compressor, a given flow rate of the first heat transfer fluid passing through the condenser and according to the value of Text
• Kl ' being the average slope AC / APcomp_in with AC being the variation of the opening of the expansion device and APcomp_in the variation of Pcomp_in measured during experimentation where the opening of the expansion device is varied for a regime of the given compressor and a given flow rate of first heat transfer fluid passing through the condenser and according to the value of Text.
• K2 being the average slope AC / A (Tsat (Pcomp_out) - Text) with AC being the variation of the opening of the expansion device and A (Tsat (Pcomp_out) - Text) the variation of (Tsat (Pcomp_out) - Text ) measured and calculated during the experiment where the opening of the expansion device is varied for a given compressor speed and a given flow rate of first heat transfer fluid passing through the condenser and according to the value of Text.
• the determination of the superheat set SHcomp_in_sp is such that:
• the value of SHcomp_in_sp allows an optimization of the coefficient of performance of the air conditioning circuit and allows the cooling fluid to be in a gaseous state at least 90% at its entry into the compressor,
• the value of SHcomp_in_sp allows the coolant to be at a temperature below the operating limit temperature of the compressor
• SHcomp_in_sp allows an optimization of the coefficient of performance of the air conditioning circuit and the cooling power of the second heat transfer fluid.
• SHcomp_in_sp_min is between 3 and 20 ° K and SHcomp_in_sp_max is between 8 and 25 ° K.
• SHcomp_in_sp_min is between 3 and 20 ° K and SHcomp_in_sp_max is between 8 and 25 ° K.
• the air conditioning circuit comprises an internal heat exchanger adapted to allow the exchange of heat energy between the refrigerant at the outlet of the condenser and the refrigerant at the outlet of the evaporator.
• FIG. 1 shows a schematic representation of an air conditioning circuit according to a first embodiment
• FIG. 1b shows a pressure / enthalpy diagram of the air conditioning circuit of FIG.
• FIG. 2a shows a schematic representation of an air conditioning circuit according to a second embodiment
• FIG. 2b shows a pressure / enthalpy diagram of the air conditioning circuit of FIG. 2a
• FIG. 3 shows a schematic representation of an air conditioning circuit according to a particular embodiment
• FIG. 4 shows a diagram of the evolution of the superheating as a function of the temperature of a first heat transfer fluid
• Figure 5 shows a diagram of the evolution of different parameters as a function of time during operation of the air conditioning circuit.
• first element or second element as well as first parameter and second parameter or else first criterion and second criterion, etc.
• first criterion and second criterion etc.
• it is a simple indexing to differentiate and name elements or parameters or criteria close but not identical.
• This indexing does not imply a priority of one element, parameter or criterion with respect to another, and it is easy to interchange such denominations without departing from the scope of the present description.
• This indexing does not imply either an order in time for example to appreciate this or that criterion.
• FIG. 1 shows a simple air conditioning circuit 1, especially for a motor vehicle, in which circulates a refrigerant.
• This air conditioning circuit 1 comprises in particular in the direction of circulation of the refrigerant fluid:
• An expansion device 7 more precisely in the present case an electronic expansion valve
• the condenser 5 is intended in particular to release the heat energy of the refrigerant in a first heat transfer fluid 50.
• This first heat transfer fluid 50 may for example be a flow of outside air when the first heat exchanger is for example disposed on the front face of the motor vehicle.
• the first coolant 50 is a fluid flowing in another temperature management loop, for example when the first heat exchanger is a two-fluid exchanger, this is particularly the case in the context of a circuit indirect air conditioning.
• the evaporator 9 is intended to recover the heat energy of a second coolant 90 and transfer it to the refrigerant.
• This second coolant 90 may for example be a flow of air to the passenger compartment when the second heat exchanger is for example disposed in a heating, ventilation and air conditioning.
• the second heat transfer fluid 90 is a fluid circulating in another temperature management loop, for example when the second heat exchanger is a two-fluid exchanger.
• the air conditioning circuit 1 also comprises a central control unit 10.
• This central control unit 10 is in particular connected to the compressor 3 to control its speed and thus control the pressure of the refrigerant.
• Central unity control 10 is also connected to the expansion device 7 to control and control its opening and thus control the loss of pressure of the refrigerant when it passes through.
• the central control unit 10 may also be connected to a first sensor 11 of the temperature Text of the first heat transfer fluid 50 before passing through the condenser 5. More precisely, Text may correspond to the ambient ambient temperature of the air.
• the central control unit 10 may be connected to a second sensor 12 of the pressure Pcomp_out of the refrigerant at the outlet of the compressor 3.
• This second sensor 12 may in particular be arranged downstream of the compressor 3 between said compressor 3 and the condenser 5 .
• the central control unit 10 can be connected to a third sensor 13 of the pressure Pcomp_in of the refrigerant before it enters the compressor 3.
• This third sensor 13 can in particular be arranged upstream of the compressor 3, between the evaporator 9 and said compressor 3.
• the central control unit may be connected to a fourth sensor 14 of the temperature Tcomp_in of the refrigerant before entering the compressor 3.
• This fourth sensor 14 may in particular be arranged upstream of the compressor 3, between the evaporator 9 and said compressor 3.
• the third 13 and fourth 14 sensors may more particularly be only one pressure / temperature sensor disposed upstream of the compressor 3, between the evaporator 9 and said compressor 3.
• the central control unit can be connected to a fifth sensor 15 of the temperature Tevapo of the second heat transfer fluid 90 after it has passed through the evaporator 9.
• the refrigerant In operation, in cooling mode, as shown in FIG. 1b, the refrigerant is in the gaseous phase at low pressure before entering the compressor 3. As it passes through the compressor 3, the refrigerant undergoes an increase in its pressure and passes at high pressure as shown by the arrow 300. The refrigerant then passes through the condenser 5 and transfer of the enthalpy to the first heat transfer fluid 50 as shown by the arrow 500. The refrigerant first crosses its saturation curve X and goes into a biphasic state. The refrigerant can also cross a second time its saturation curve X to go into the liquid phase. The difference between the temperature of the refrigerant at the outlet of condenser 5 and its saturation temperature at this pressure is called subcooling SC.
• the refrigerant then passes through the expansion device 7 and undergoes a loss of pressure to pass at low pressure, as shown by the arrow 700.
• the refrigerant again crosses its saturation curve X and goes into a two-phase state.
• the refrigerant then passes through the evaporator 9 in which the refrigerant absorbs heat energy from the second heat transfer fluid 90, cooling the latter, as shown by the arrow 900.
• the refrigerant passes through its saturation curve X and then returns to gas phase before joining the compressor 3.
• the difference between the temperature Tcomp_in of the refrigerant before it passes through the compressor 3 (measured by the fourth sensor 14) and its saturation temperature at this pressure Tsat (Pcomp_in), corresponds to an overheating SHcomp_in refrigerant.
• the air conditioning circuit 1 may also include an internal heat exchanger 20 adapted to allow heat energy to be exchanged between the refrigerant at the outlet of the condenser 5 and the refrigerant at the outlet of the evaporator 9
• This internal heat exchanger 20 comprises in particular an inlet and a coolant outlet coming from the condenser 5, as well as an inlet and a coolant outlet of the evaporator 9.
• the steps are similar to those of FIGS. 1a and 1b, with the difference that the internal heat exchanger absorbing the enthalpy with the refrigerant as shown by the arrow 200a and transferring it to the refrigerant at the outlet of the evaporator 9 as shown by the arrow 200b.
• the subcooling SR of the refrigerant before it passes through the expansion device 7 and the superheat SHcomp_in of the refrigerant before it enters the compressor 3 are both increased under the effect of the heat exchanger 20. This allows in particular an increase in the coefficient of performance of the air conditioning circuit 1.
• the air conditioning circuit 1 may for example be an indirect reversible air conditioning circuit 1 as shown in Figure 3. This indirect reversible air conditioning circuit 1 can operate in different modes of operation including a cooling mode.
• This indirect reversible air conditioning circuit 1 comprises in particular:
• a second loop of coolant B in which the first coolant 50 circulates and
• a two-fluid heat exchanger corresponding to the condenser 5 arranged jointly on the first refrigerant fluid loop A and on the second heat transfer fluid loop B, so as to allow exchanges of heat between said first refrigerant loop A and said second loop heat transfer fluid B.
• the first coolant loop A shown in solid line in FIG. 3, comprises more particularly in the direction of circulation of the refrigerant fluid:
• a first expansion device 7 more specifically an electronic expansion valve
• an evaporator 9 being intended to be traversed by the second heat transfer fluid 90 which here is an interior air flow to the motor vehicle towards the passenger compartment, 0 a second decompressing device 21, for example a tube orifice,
• the bypass line 30 can more specifically connect a first connection point 31 and a second connection point 32.
• the first connection point 31 is preferably arranged, in the flow direction of the coolant, downstream of the evaporator 9, between said evaporator 9 and evapo-condenser 13. More particularly, and as illustrated in FIG. first connection point 31 is disposed between the evaporator 9 and the second expansion device 21. It is however quite possible to imagine that the first connection point 31 is disposed between the second expansion device 21 and evapo-condenser 13 as long as the refrigerant has the ability to bypass the second expansion device 21 or to pass through without suffering pressure loss.
• the second connection point 32 is, for its part, preferably disposed downstream of the evapo-condenser 13, between the said evapo-condenser 13 and the compressor 3.
• the indirect reversible air conditioning circuit 1 also comprises a device for redirecting the refrigerant fluid from the evaporator 9 to evapo-condenser 13 or to the bypass line 30.
• This device for redirecting the refrigerant fluid from the evaporator 9 can comprise in particular:
• a first stop valve 22 arranged downstream of the first connection point 31 between said first connection point 31 and the second expansion device 21,
• Another alternative may also be to have a three-way valve at the first connection point 31.
• stop valve non-return valve, three-way valve or expansion device with stop function, here means mechanical or electromechanical elements that can be controlled by the central control unit 10.
• the first coolant loop A may comprise, in addition to an internal heat exchanger 20, a second internal heat exchanger 20 'allowing a heat exchange between the high-pressure refrigerant at the outlet of the heat exchanger.
• high-pressure refrigerant fluid is meant by a coolant having undergone a pressure increase at the compressor 3 and that it has not yet suffered a loss of pressure due to the electronic expansion valve 7 or the tube orifice 11.
• This second internal heat exchanger 20 comprises in particular an inlet and a coolant outlet coming from the first connection point 31, as well as a high-pressure refrigerant inlet and outlet from the internal heat exchanger 20.
• At least one of the two internal heat exchangers 20, 20 ' may be a coaxial heat exchanger, that is to say comprising two coaxial tubes and between which the exchange of heat is carried out. heat.
• the internal heat exchanger 20 may be a coaxial internal heat exchanger with a length of between 50 and 120 mm while the second internal heat exchanger 20 'may be a coaxial internal heat exchanger with a length of between 200 and 700mm.
• the first coolant loop A may comprise a desiccant bottle 18 disposed downstream of the bifluid heat exchanger 5, more precisely between said two-fluid heat exchanger 5 and the internal heat exchanger 20.
• a desiccant bottle 18 disposed on the high pressure side of the air conditioning circuit ie downstream of the compressor 3 and upstream of an expansion device, has a smaller footprint and a reduced cost compared to other phase separation solutions as an accumulator which would be disposed on the low pressure side of the air conditioning circuit, ie upstream of the compressor 3, in particular upstream of the internal heat exchanger 20.
• the second heat transfer fluid loop B shown in a line comprising three dashes and two dots in FIG. 3, may comprise:
• a first circulation pipe 70 of the first heat transfer fluid 50 having an internal heater 54 intended to be traversed by the inner air stream 90 to the motor vehicle, and connecting a first junction point 61 arranged downstream of the heat exchanger bifluid 5 and a second junction point 62 arranged upstream of said bifluid heat exchanger 5,
• the indirect reversible air-conditioning circuit 1 comprises, within the second heat-transfer fluid loop B, a device for redirecting the coolant from the two-fluid heat exchanger 5 to the first circulation pipe 70 and / or to the second water pipe. circulation 60.
• the device for redirecting the heat transfer fluid from the two-fluid heat exchanger 5 can in particular comprise a fourth stop valve 63 arranged on the second circulation pipe 60 in order to block or not the first fluid. coolant and prevent it from circulating in said second circulation pipe 60.
• the indirect reversible air conditioning circuit 1 may also include an obstruction flap 310 of the interior air flow 100 passing through the third heat exchanger 54.
• This embodiment makes it possible in particular to limit the number of valves on the second heat transfer fluid loop B and thus makes it possible to limit the production costs.
• the device for redirecting the heat transfer fluid from the two-fluid heat exchanger 5 may in particular comprise a fourth stop valve 63 disposed on the second circulation pipe 60 in order to block the fluid or not. coolant and prevent it from circulating in said second flow line 60, and a fifth stop valve disposed on the first flow line 70 to block or not the heat transfer fluid and prevent it from circulating in said first pipe 70.
• the second heat transfer fluid loop B may also include an electric heating element 55 of the heat transfer fluid.
• Said electric heating element 55 is in particular disposed, in the direction of circulation of the coolant, downstream of the bifluid heat exchanger 5, between said two-fluid heat exchanger 5 and the first junction point 61.
• the coolant does not pass through the evapolver 13 but passes through the bypass line 30.
• the first refrigerant 50 passes through the external radiator 64 in order to evacuate heat energy. in the external airflow 200.
• the coolant passes successively through a compressor 3, a condenser 5, an expansion device 7 and an evaporator 9.
• the present invention relates in particular to a method for managing the air conditioning circuit 1 in cooling mode and more specifically to managing the control of the opening of the expansion device 7 and thus the loss of pressure of the refrigerant when it passes through said device relaxing 7.
• the management method comprises in particular:
• SHcomp_in_sp is between a minimum superheat SHcomp_in_sp_min and a maximum superheat Shcomp_in_sp_max
• a second step of opening the expansion device 7 according to Cestim and superheating control SHcomp_in by varying the opening of the expansion device 7 so as to achieve the set superheat SHcomp_in_sp and maintain SHcomp_in between SHcomp_in_sp_min and SHcomp_in_sp_max.
• the calculation of the Cestim opening of the expansion device 7 is carried out according to one of the following formulas:
• Tevapo is the temperature of the second heat transfer fluid 90 at the outlet of the evaporator 9, measured by the fifth sensor 15,
• Tevapo_sp is an setpoint temperature of the second heat transfer fluid 90 at the outlet of the evaporator 9. This setpoint temperature Tevapo_sp is determined by the central control unit 10 as a function of the temperature required by the user inside the cabin, for example .
• Tsat (Pcomp_out) is the saturation temperature of the coolant at the pressure Pcomp_out of the refrigerant at the outlet of the compressor 3, the pressure Pcomp_out being measured by the second sensor 12.
• Text is the temperature of the first heat transfer fluid 50 before it passes through the condenser 5, measured by the first sensor 11.
• Pcomp_in is the pressure of the refrigerant at the inlet of the compressor 3, measured by the third sensor 13.
• Psat (Tevapo_sp) is the saturation pressure of the coolant at the setpoint temperature Tevapo of the second heat transfer fluid 90 at the outlet of the evaporator 90.
• Kl corresponds to the average slope AC / Tevapo with AC being the variation of the opening of the expansion device 7 and the variation of Tevapo ATevapo measured during experimentation where the opening of the expansion device 7 is varied.
• a given speed of the compressor 3 a given flow rate of the first heat transfer fluid 50 passing through the condenser 5 and according to the value of Text.
• This constant Kl is determined by experimentation and by the data stored in the central control unit 10.
• the variation of the opening of the expansion device 7 AC takes place between its maximum opening and its minimum opening.
• ⁇ corresponds to the average slope ACIAPcomp_in with AC being the variation of the opening of the expansion device 7 and APcomp_in the variation of Pcomp_in measured during experimentation where the opening of the expansion device 7 is varied for a regime of the given compressor 3 and a given flow rate of first heat transfer fluid 50 passing through the condenser 5 and according to the value of Text.
• This constant ⁇ is determined by experimentation and by the data stored in the central control unit 10.
• the variation of the opening of the expansion device 7 AC takes place between its maximum opening and its minimum opening.
• K2 corresponds to the average slope AC / A (Tsat (Pcomp_out) - Text) with AC being the variation of the opening of the expansion device 7 and of A (Tsat (Pcomp_out) - Text) the variation of (Tsat (Pcomp_out) - Text) measured and calculated during the experiment where the opening of the expansion device 7 is varied for a given speed of the compressor 3 and a given flow rate of the first heat transfer fluid 50 passing through the condenser 5 and according to the value of Text .
• This constant ⁇ is determined by experimentation and by the data stored in the central control unit 10.
• the variation of the opening of the expansion device 7 AC takes place between its maximum opening and its minimum opening.
• SHcomp_in_sp_min and SHcomp_in_sp_max are obtained by experimentation and are determined according to:
• the data concerning SHcomp_in_sp_min and Shcomp_in_sp_max are stored in the central control unit 10.
• SHcomp_in_sp_min can be between 3 and 20 ° K and SHcomp_in_sp_max between 8 and 25 ° K.
• SHcomp_in_sp_min and SHcomp_in_sp_max are variable depending on the nature of the coolant and the architecture of the air conditioning circuit 1.
• the value of Shcomp_in_sp always between SHcomp_in_sp_min and SHcomp_in_sp_max, allows an optimization of the coefficient of performance of the air conditioning circuit 1 and allows the cooling fluid to be in a gaseous state at minus 90% when entering the compressor 3.
• SHcomp_in_sp For a value of Text greater than a defined value T2, the value of SHcomp_in_sp, always between SHcomp_in_sp_min and SHcomp_in_sp_max, allows the refrigerant to be at a temperature below the operating limit temperature of the compressor 3 and thus avoids that the latter does not stop by getting in safety.
• SHcomp_in_sp For a value of Text between Tl and T2, the value of SHcomp_in_sp, always between SHcomp_in_sp_min and SHcomp_in_sp_max, allows an optimization of the coefficient of performance of the air conditioning circuit 1 and the cooling power of the second heat transfer fluid 90.
• the control unit 10 will decrease the opening of the expansion device 7 to increase the superheat SHcomp_in.
• SHcomp_in is greater than SHcomp_in_sp_max while the control unit 10 will increase the opening of the expansion device 7 in order to reduce the superheat SHcomp_in.
• the increase or decrease in the opening of the expansion device 7 is preferably performed by an integral proportional controller.
• SHcomp_in is between SHcomp_in_sp_min and SHcomp_in_sp_max, the increase or decrease of the opening of the expansion device 7 is preferably carried out by a proportional controller.
• FIG. 5 shows a diagram showing in solid lines the evolution, as a function of time, expressed in minutes, of:
• the refrigerant chosen is R134a and the temperature Text is 45 ° C.
• the management method according to the invention allows an increase of the superheat SHcom_in 102b with respect to the superheat SHcom_in 102a.
• This superheating SHcom_in 102b is more important because the opening 103b according to the invention is smaller than the opening 103a according to the prior art. Due to this superheating SHcom_in 102b more important, the temperature Tevapo 101b according to the invention is weaker than the temperature Tevapo 101a according to the prior art. The coefficient of performance is then increased compared to the prior art, because the compressor 3 is at an identical speed either for the prior art or for the management method according to the invention.
• the management method according to the invention allows good management and good control of the opening of the expansion device 7 allowing a good coefficient of performance of the air conditioning circuit 1 in cooling mode.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Mechanical Engineering (AREA)
• Thermal Sciences (AREA)
• General Engineering & Computer Science (AREA)
• Air-Conditioning For Vehicles (AREA)
• Compression-Type Refrigeration Machines With Reversible Cycles (AREA)

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