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GB2530165A - Method of operating an air conditioning device and air conditioning device - Google Patents

Method of operating an air conditioning device and air conditioning device Download PDF

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Publication number
GB2530165A
GB2530165A GB1513896.9A GB201513896A GB2530165A GB 2530165 A GB2530165 A GB 2530165A GB 201513896 A GB201513896 A GB 201513896A GB 2530165 A GB2530165 A GB 2530165A
Authority
GB
United Kingdom
Prior art keywords
refrigerant
air conditioning
conditioning device
cycle system
boundary condition
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB1513896.9A
Other versions
GB201513896D0 (en
Inventor
Santosh Jangamwadimath
Shivakumar Banakar
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mercedes Benz Group AG
Original Assignee
Daimler AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Daimler AG filed Critical Daimler AG
Priority to GB1513896.9A priority Critical patent/GB2530165A/en
Publication of GB201513896D0 publication Critical patent/GB201513896D0/en
Publication of GB2530165A publication Critical patent/GB2530165A/en
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • B60H1/00642Control systems or circuits; Control members or indication devices for heating, cooling or ventilating devices
    • B60H1/00814Control systems or circuits characterised by their output, for controlling particular components of the heating, cooling or ventilating installation
    • B60H1/00878Control systems or circuits characterised by their output, for controlling particular components of the heating, cooling or ventilating installation the components being temperature regulating devices
    • B60H1/00899Controlling the flow of liquid in a heat pump system
    • 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
    • F25B45/00Arrangements for charging or discharging refrigerant
    • 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
    • B60H1/3211Control means therefor for increasing the efficiency of a vehicle refrigeration cycle
    • 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
    • B60H1/323Cooling devices using compression characterised by comprising auxiliary or multiple systems, e.g. plurality of evaporators, or by involving auxiliary cooling devices

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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)

Abstract

An air conditioning system 10, ideally of a motor vehicle 40, comprises a condenser 14, evaporator 18, compressor 20 and an expansion device 16 connected with one another by a circuit 12 containing a first refrigerant 24. The system includes an exchanging unit 28 operable to remove the first refrigerant from the circuit and replace with a second refrigerant 26 if a predetermined value (50, figure 2) of a boundary condition of the system is reached. Ideally the first refrigerant is carbon dioxide (46, figure 2) and the second refrigerant is R134a (48, figure 2) and the boundary condition corresponds to an ambient temperature (44, figure 2) such that if the ambient temperature exceeds the predetermined value, e.g. 40 degrees centigrade, R134a is used in place of carbon dioxide, thereby increasing the coefficient of performance (COP) of the system. The exchanging unit ideally comprises first and second reservoirs 36,38 containing the refrigerants and first and second valves 32,34 all located between the condenser and the expansion device. A counter-stream heat exchanger 22 and control unit 30 may also be included. A method of operating an air conditioning device is also claimed.

Description

Method for operating an air conditioning device and air conditioning device The invention relates to a method for operating an air conditioning device according to the preamble of patent claim 1. Furthermore, the invention relates to an air conditioning device, in particular for a motor vehicle according to the preamble of patent claim 5.
Air conditioning devices are widespread in the automotive sector, wherein different kinds of fluids are used as ref rigerants in order to meet the requirements for cooling efficiency and for an operating efficiency of the respective air conditioning device. Document WO 2014/1 56190 Al discloses a dual refrigeration device in which different refrigerant compositions are used parallel in order to both meet requirements for low-temperature-conditions and high-temperature-conditions.
Document KR20100136631 A discloses a two-part mixed refrigerant, which is provided to replace R134a. The two-part mixed refrigerant may be used for a freezer/conditioner and comprises 85.0 to 99.9 weight % of HFO-l 234yf and 0.1 to 15.0 weight % of Hi 34a. The refrigerant there lowers flammability and durability of a system due to a low discharged temperature of a compressor.
It is an object of the present invention to provide a method and an air conditioning device of the afore-mentioned kind which allow for an especially efficient conditioning.
This object is solved by a method having the features of patent claim 1 as well as by an air conditioning device having the features of patent claim 5. Advantageous embodiments with expedient developments of the invention are indicated in the other patent claims.
In order to provide a method of the kind indicated in the preamble of patent claim 1, which allows for an especially efficient conditioning, according to the present invention the at least one refrigerant is removed from the cycle system and at least a second refrigerant is discharged into the cycle system by an exchanging unit if a predetermined value of a boundary condition of the air conditioning device is reached. In other words, the at least one refrigerant is replaced by the second refrigerant, if the predetermined value is reached. This boundary condition may correspond to a minimum heat rejection temperature (minimum HRT) or ambient temperature to name only an example for such a boundary condition. The at least one refrigerant may have an especially high relative coefficient of performance (relative COP) within a certain boundary condition range, which may be limited by the predetermined value. As soon as the predetermined value is reached, the second refrigerant may be more appropriate for its usage within the cycle system of the air conditioning device. Thus, the relative COP of the second refrigerant may be higher than a relative COP of the at least one refrigerant, which means that the air conditioning device may be operated with the second refrigerant with higher efficiency (more efficient conditioning) as soon as the predetermined value is reached or even exceeded. This allows for an especially simple and efficient operation of the air conditioning device, wherein the air conditioning device may be designed especially compact. Thus, there is no need for using e.g. two condensers, evaporators, compressors or thermal expansion valves, each for one of the refrigerants. The air conditioning device is especially suitable for the use in a motor vehicle or other vehicles.
Furthermore the air conditioning device is also suitable for stationary applications, such as for air conditioning of buildings and for commercial use.
In a particularly advantageous embodiment of the invention, the boundary condition corresponds to an ambient temperature of the air conditioning device. The ambient temperature can be determined easily and exactly and is an especially appropriate boundary condition in dependency of which the air conditioning device may be operated.
It has turned out to be particularly advantageous, if CO2 is used as one of the refrigerants.
Carbon dioxide (GO2) is especially eco-friendly and available without difficulty.
In a further particularly advantageous embodiment of the invention Ri 34a is used as one of the ref rigerants. R134a is commonly used in the automotive sector, and is thus available without problems. Furthermore, R134a has no destructive effect on the ozone layer.
The invention further relates to an air conditioning device of the kind indicated in the preamble of patent claim 5, which also allows for an especially efficient conditioning. In order to achieve such an especially efficient conditioning, according to the invention an exchanging unit is provided, by means of which the at least one refrigerant is removable from the cycle system and by means of which at least a second refrigerant is dischargeable into the cycle system if a predetermined value of a boundary condition of the air conditioning device is reached. The exchanging unit may comprise e.g. one or more valves, a control unit as well as a sensor for detecting a value of the boundary condition. By means of the one or more valves, the filling and additionally or alternatively the discharging of different tank elements, each containing one of the refrigerants may be achieved, wherein the valves are controlled by means of the control unit of the exchanging unit. The valves may be operated in dependency on the values, which are measured by the sensor, wherein the exchanging unit exchanges the refrigerants in the cycle system, as soon as the measured value (measured by means of the sensor) reaches the predetermined value.
Advantageous embodiments of the method according to the invention are to be regarded as advantageous embodiments of the air conditioning device according to the invention and vice versa.
Further advantages, features, and details of the invention derive from the following description of a preferred embodiment as well as from the drawings. The features and feature combinations previously mentioned in the description as well as the features and feature combinations mentioned in the following description of the figures and/or shown in the figures alone can be employed not only in the respectively indicated combination but also in other combination or taken alone without leaving the scope of the invention.
The drawings show in: Fig. 1 A schematic illustration of an embodiment of a cycle system of an air conditioning device according to the invention; and Fig. 2 A diagram showing a relative coefficient of performance in dependency on a minimum heat rejection temperature of two different fluids, which each may be used as refrigerants of the air conditioning device.
Fig. 1 shows a schematic illustration of an air conditioning device 10, which is used in a motor vehicle 40. In the present embodiments, the air conditioning device 10 corresponds to a "heating, ventilation and air conditioning system" (HVAC system). The air conditioning device 10 comprises a cycle system 12 with two tank elements 36, 38, which are integrated to the cycle system 12. The tank element 36 corresponds to a first tank element, which is used as a reservoir for a first refrigerant 24, wherein the first refrigerant 24 corresponds to CO2 at present. The tank element 38 corresponds to a second tank element, which is used as a reservoir for a second refrigerant 26, wherein the second refrigerant 26 corresponds to Ri 34a. The air conditioning device 10 also comprises an exchanging unit 28, by means of which the first refrigerant 24 is removable from the cycle system 12 and by means of which the second refrigerant 26 is dischargeable into the cycle system 12. The cycle system 12 also comprises a condensation device 14, which is designed as a condenser, for condensing the respective refrigerant 24, 26, an expansion device 16, which is designed as a thermal expansion valve (TXV) for expanding the respective refrigerant 24, 26, an evaporation device 18, which is designed as an evaporator for evaporating the respective refrigerant 24, 26 and a compression device 20, which is designed as a compressor for compressing the respective refrigerant 24, 26. The air conditioning device also comprises a heat exchanging device 22, which is designed as an internal heat exchanger (IHX) and which helps increasing the cooling capacity of the air conditioning device 10. The heat exchanging device 22 is also integrated into the cycle system 12, wherein the heat exchanging device 22 is used for exchanging heat between the respective refrigerant 24, 26 which flows from the condensation device 14 towards the heat exchanging device 22 according to a flow direction 13, which is marked with an arrow, and the respective refrigerant 24, 26 which flows from the evaporation device 18 into the heat exchanging device 22, wherein a flow path from the evaporation device 18 to the heat exchanging device 22 is indicated by a dashed line. Thus, the IHX (heat exchanging device 22) is operated as counter stream heat exchanger.
In order to operate the air conditioning device 10 especially efficient, the exchanging unit 28 replaces the first refrigerant 24 by the second refrigerant 26 if a predetermined value of a boundary condition 44 of the air conditioning device 10 is reached. Both the predetermined value 50 and the boundary condition 44 are indicated in Fig. 2. In order to replace the first refrigerant 24 by the second refrigerant 26 the exchanging unit 28 comprises two valves at presents, namely a first valve 32 and a second valve 34.
Furthermore, the exchanging unit 28 comprises a control unit 30 for controlling the valves 32, 34, wherein the control unit 30 also comprises a sensor (which is not shown here) for measuring values concerning the boundary condition 44. In the present embodiments, the boundary condition 44 corresponds to an ambient temperature or a minimum heat rejection temperature (minimum HRT), which is measured by the sensor.
The firs! valve 32 is arranged upstream of the tank elements 36, 38, wherein the tank elements 36, 38 are arranged parallel to each other. The first valve 32 is used to discharge the cycle system 12 and thus to fill the respective refrigerant 24, 26 which is currently used in the cycle system 12 according to the flow direction 13, into the respective tank element 36, 38.
The second valve 34 is arranged downstream of the two tank elements 36, 38 and is thus arranged between the two parallel tank elements 36, 38 and the heat exchanging device 22 according to the present embodiment. The second valve 34 is used to fill the respective refrigerant 24, 26, which shall be used instead of the other refrigerant 24, 26 into the cycle system 12.
The air conditioning device 10 may also comprise a refrigerant separator, which is not shown at present. This refrigerant separator may be integrated into the cycle system and may be used to separate residual amounts of the respective refrigerants 24, 26. Thus, such a refrigerant separator may be useful to remove e.g. remaining residual amounts of the first refrigerant 24 from the cycle system 12 after a main part of the first refrigerant 24 has already been filled into the first tank element 36, when the cycle system 12 has already been filled with the second refrigerant 26. By using such a refrigerant separator, the efficiency of the air conditioning device 10 can be increased.
In the diagram shown in Fig. 2, the boundary condition 44 corresponds to the abscissa of the diagram. A relative coefficient of performance (relative COP) is plotted as ordinate 42 of the diagram. Furthermore, a CO2-curve 46 of the first refrigerant 24 and a Ri 34a-curve 48 of the second refrigerant 26 are illustrated in the diagram. The R134a-curve 48 is very similar to a curve of HCFC22, which corresponds to chlorofluorocarbon (CFC). In other words, the second refrigerant 26 (Ri 34a) has almost the same properties according to the ratio "relative COP/HRP" but is less harmful to the environment than HCFC22.
In Fig. 2, the predetermined value 50 corresponds to an intersection point of the two curves 46, 48, wherein the predetermined value 50 corresponds to a value of 40t of the ambient temperature or the minimum HRT. In other words, in the present embodiment the exchanging unit 28 replaces the first refrigerant 24 (C02) by the second refrigerant 26 (R134a) at the predetermined value 50 of 4093.
The air conditioning device 10 according to the invention uses the different refrigerants 24, 26 as a working fluid in the cycle system 12 in dependency on the ambient temperature, at which the air conditioning device 10 is being operated. CC2, as the first refrigerant 24, has a better efficiency at lower ambient temperatures (below 4093) than Ri 34a. Ri 34a, as the second refrigerant 26, has a better efficiency for higher ambient temperatures (above 40t) than CO 2* Hence, the proposed air conditioning device 10 may be operated with two different refrigerants 24, 26, wherein the selection of the refrigerant 24, 26 is based on the ambient temperature.
The efficiency (relative COP) is improved, when the air conditioning device 10 is operated with CO2 as the working fluid when the ambient temperatures are below 40'C. The efficiency of the air conditioning device 10 is improved, when the air conditioning device is operated with Ri 34a as the working fluid at ambient temperatures above 40t. The efficiency of the air conditioning device 10 has a direct implication on the fuel economy of the motor vehicle 40, hence improving the efficiency of the air conditioning device 10 results in better fuel economy of the motor vehicle 40.
List of reference signs air conditioning device 1 2 cycle system 13 flow direction 14 condensation device 16 expansion device 18 evaporation device compression device 22 heat exchanging device 24 first refrigerant 26 second refrigerant 28 exchanging unit control unit 32 first valve 34 second valve 36 first tank element 38 second tank element motor vehicle 42 ordinate 44 boundary condition 46 C02-curve 48 R134a-curve predetermined value

Claims (6)

  1. Claims Method for operating an air conditioning device (10), in particular fora motor vehicle (40), in which at least one refrigerant (24) is transported through a cycle system (12) of the air conditioning device (10) in which the at least one refrigerant (24) is -condensed by at least one condensation device (14), -expanded by at least one expansion device (16), -evaporated by at least one evaporation device (18), and -compressed by at least one compression device (20), characterized in that, the at least one refrigerant (24) is removed from the cycle system (12) and at least a second refrigerant (26) is discharged into the cycle system (12) by an exchanging unit (28) if a predetermined value (50) of a boundary condition (44) of the air conditioning device (10) is reached.
  2. 2. Method according to claim 1, characterized in that, the boundary condition (44) corresponds to an ambient temperature of the air conditioning device (10).
  3. 3. Method according to claim 1 or 2, characterized in that, CO2 is used as one of the ref rigerants (24, 26).
  4. 4. Method according to any one of the preceding claims, characterized in that, R134a is used as one of the ref rigerants (24, 26).
  5. 5. Air conditioning device (10), in particular for a motor vehicle (40), having at least one refrigerant (24) and having a cycle system (12) with -at least one condensation device (14) for condensing the refrigerant (24), -at least one expansion device (16) for expanding the refrigerant (24), -at least one evaporation device (18) for evaporating the refrigerant (24). and -at least one compression device (20) for compressing the refrigerant (24), characterized in that, an exchanging unit (28) is provided, by means of which the at least one refrigerant (24) is removable from the cycle system (12) and by means of which at least a second refrigerant (26) is dischargeable into the cycle system (12) if a predetermined value (50) of a boundary condition (44) of the air conditioning device (10) is reached.
  6. 6. Air conditioning device (10) according to claim 4, characterized in that, at least two tank elements (36, 38) are provided each for storing one of the refrigerants (24, 26), wherein the at least two tank elements (36, 38) are arranged downstream of the condensation device (14) and upstream of the expansion device (16).
GB1513896.9A 2015-08-06 2015-08-06 Method of operating an air conditioning device and air conditioning device Withdrawn GB2530165A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB1513896.9A GB2530165A (en) 2015-08-06 2015-08-06 Method of operating an air conditioning device and air conditioning device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB1513896.9A GB2530165A (en) 2015-08-06 2015-08-06 Method of operating an air conditioning device and air conditioning device

Publications (2)

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GB201513896D0 GB201513896D0 (en) 2015-09-23
GB2530165A true GB2530165A (en) 2016-03-16

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GB1513896.9A Withdrawn GB2530165A (en) 2015-08-06 2015-08-06 Method of operating an air conditioning device and air conditioning device

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090049848A1 (en) * 2007-07-26 2009-02-26 Ford Global Technologies, Llc Air Conditioning System for a Motor Vehicle and Method for its Operation
CN203881018U (en) * 2014-06-11 2014-10-15 陕西重型汽车有限公司 Automotive air conditioner system capable of automatically supplementing refrigerants

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090049848A1 (en) * 2007-07-26 2009-02-26 Ford Global Technologies, Llc Air Conditioning System for a Motor Vehicle and Method for its Operation
CN203881018U (en) * 2014-06-11 2014-10-15 陕西重型汽车有限公司 Automotive air conditioner system capable of automatically supplementing refrigerants

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Publication number Publication date
GB201513896D0 (en) 2015-09-23

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