DE102012212227A1 - Cooling system, particularly vehicle air conditioning system, has heat transmission device with one or multiple thermoelectric elements, particularly Peltier elements, which are connected with subcooling path - Google Patents

Abstract

The cooling system (10) has a coolant circuit, which comprises an evaporator (1), a compressor (2), a capacitor (3) and an expansion device (4), and a heat transmission device (7), which comprises a subcooling path for cooling the coolant before entering the expansion device. The heat transmission device has one or multiple thermoelectric elements (14), particularly Peltier elements, which are connected with the subcooling path. The heat transmission device is structurally integrated in the capacitor. Independent claims are included for the following: (1) a motor vehicle with a recuperation device; and (2) a method for operating a cooling system in a motor vehicle.

Description

Technical area

The invention relates to a refrigeration system, in particular a vehicle air conditioning system, according to the preamble of claim 1.

State of the art

Refrigeration systems have a wide field of application, which extends to many areas, for example in industry and everyday life. Refrigeration systems are often used in air conditioning systems for the air conditioning of rooms and vehicles.

Conventional vehicle air-conditioning systems typically have a fluid refrigerant in the refrigeration system as the working medium. Thus, in a cooling mode of the air conditioner, the refrigerant is vaporized in an evaporator, wherein in order to achieve the cooling effect, the necessary heat of vaporization is taken from the environment, for example, from passing vehicle interior air. Furthermore, the heat absorbed in the coolant circuit at another point of the vehicle is discharged again by the refrigerant is condensed in a condenser or condenser, which in turn must be cooled to remove the released during this condensation heat.

At the condenser of conventional air conditioning circuits, the refrigerant first undergoes a desuperheating to be stored as a saturated liquid in a collector, where the refrigerant may be present in part in two phases.

Subsequently, the saturated refrigerant liquid is further cooled in a subcooling section, for example, to 5 K lower than the corresponding condensation temperature, whereby more heat is taken from the refrigerant. Furthermore, as a result of this, the vapor content present after a subsequent expansion of the refrigerant, for example by an expansion valve, may become smaller, whereby the more the subcooled, the smaller the vapor content becomes. This can minimize unwanted liquid-to-vapor conversion without effective heat absorption. Furthermore, less refrigerant flow is required to achieve a certain cooling capacity on the evaporator.

For the reasons mentioned, it is therefore expedient to further expand the described supercooling effect in order to further increase the enthalpy flow in the air conditioning system. In particular, it is known to provide further cooling of the refrigerant below the ambient temperature. However, according to a proposal that has been rarely used in the series, the refrigerant is subcooled after the condenser by means of internal heat exchange (IWT) below the ambient temperature. In such a method, however, the refrigerant after the evaporator, where it is typically in the superheated gaseous state, is heated to a higher degree. This means, among other things, that the compressor arranged between the evaporator and the condenser, which compresses the refrigerant before it enters the condenser, is subjected to greater stress. Thus, due to a higher volumetric gas flow rate at the compressor, the recovered enthalpy flow must be partially recirculated by mechanical work. However, this has a higher energy consumption in the motor vehicle, and since the air compressor is usually operated via a belt drive, in particular, a higher fuel consumption. The use of an internal heat exchanger normally reduces overall drive power. Due to the cooling of the refrigerant on the high-pressure side, a lesser mass flow of refrigerant is needed altogether. Although the specific compression work on the compressor increases due to greater overheating, the product of mass flow and specific compressor work with IWT is typically smaller than without IWT.

Presentation of the invention, object, solution, advantages

It is an object of the invention to provide a refrigeration system and a vehicle with a refrigeration system or an air conditioning system, in which an efficient cooling is made possible by introducing an increased supercooling performance, without this being accompanied at the same time by a consequent increased fuel and energy consumption.

This is achieved with the features of claim 1, according to which a refrigeration system, in particular a vehicle air conditioning system with a refrigerant circuit comprising an evaporator, a compressor, a condenser, and an expansion device, and with a heat transfer device, which is arranged upstream of the expansion device subcooling to Cooling of a refrigerant before entering the expansion device, is equipped, wherein the heat transfer device comprises one or more connected to the subcooling thermoelectric elements.

As an advantage of the invention, greater undercooling of the refrigerant liquefied at the condenser can be accomplished in the refrigeration cycle without having to remove this subcooling power internally from the cooling circuit itself. This is the case, since the subcooling capacity according to the invention is supplied to the refrigeration cycle directly at the location of the subcooling section by means of the thermoelectric elements. As a result, in particular the use of electrical energy present, generated or stored anyway in the vehicle is favorably promoted and made possible. By the measure according to the invention is further promoted to regulate the refrigerant circuit in a simple manner such that the receipt of the climate comfort, the dynamic onset of subcooling and the allowable / bidded withdrawal of the mechanical compressor performance are matched.

The thermoelectric elements are preferably designed as Peltier elements.

As a result, the refrigeration system according to the invention can be realized particularly robust and flexible. Thus, the conversion of electrical power in cooling capacity with Peltier elements without moving parts can be implemented. Also, Peltier elements can be flexibly adapted to different geometries of heat exchangers in a simple manner. Furthermore, unlike electric motors, Peltier elements are tolerant of a wider voltage and current range.

According to another aspect of the invention, there is provided a motor vehicle having an air conditioner, the air conditioner having a refrigerant circuit with an expansion device disposed between a condenser for liquefying a refrigerant and an evaporator, and a subcooling path. The subcooling path is arranged in the refrigerant circuit in front of the expansion device and serves to subcool the liquefied refrigerant. Furthermore, the subcooling path is formed as part of a heat transfer device and has one or more thermoelectric elements connected to the cooling section, in particular Peltier elements.

In an advantageous embodiment of the invention, the motor vehicle has a recuperation device for obtaining and storing electrical energy. Preferably, the recuperation device has a coupled to a drive train of the motor vehicle electric generator alternator). Here, the recuperation can be done in non-powered overrun mode, such as in downhill roles without drive power, as well as in active braking mode.

In this embodiment, an electrical energy coming from the recuperation device can be utilized by the thermoelectric elements of the refrigeration system according to the invention, in particular in a case in which the recuperation energy represents a potentially available surplus energy which is currently not needed or used by any other aggregate.

The recuperation device may typically be coupled to an energy storage device of the motor vehicle, which is arranged to supply the thermoelectric element with electrical energy. Often lead-acid batteries are used, where the charge capacity is very limited. Alternatively, vehicles with lithium-ion batteries are conceivable. If a maximum achievable by recuperation electric power at full battery can not be completely removed by other consumers, thanks to the invention otherwise unused energy saving potentials can be used.

According to a variant of the above-mentioned embodiment, the motor vehicle is a so-called micro-hybrid vehicle. As a micro-hybrid vehicle is generally understood vehicles, which can recuperate parts of their kinetic energy through the alternator, but otherwise have no other basic features of a hybrid vehicle, such as an electric drive assistance or electric driving.

In micro hybrids, the ancillaries are usually still mechanically driven by a belt drive, instead of the already possible today, electrical units. These conventionally driven units are unable to absorb electrical power from the recuperation, which also applies to the air conditioning compressor.

Especially with an application of the invention in such a micro hybrid vehicle, excess electrical power can thus be supplied to a useful, but less costly, use without, for example, having to exchange or retrofit an existing, non-adapted air conditioning compressor or having to take other expensive measures.

The invention can be used advantageously not only in a belt-driven compressor. If an electric compressor instead of a belt-driven compressor is used from the outset, the electric compressor can then absorb electrical power immediately. The invention can be used advantageously in particular when the total consumption of electrical energy with the same cooling capacity of the evaporator is lower than the higher consumption of the electric compressor of a system without thermoelectrics.

The heat transfer device according to the invention can be designed as a direct subcooler or as an indirect subcooler. In the direct subcooler embodiment, the subcooler may be air cooled, in the indirect subcooler embodiment it is fluid or water cooled.

According to a preferred embodiment, the heat transfer device is swept out as an indirect subcooler. This can simplify a problem remedy that starting from conventional capacitors, the subcooling, measured in terms of their Enthalpieabgabe, occupies a relatively high area compared to the condensation section. This is due to the fact that a lowering of the refrigerant temperature makes the heat transfer to the ambient air increasingly difficult. In addition, can be advantageously ensured in the embodiment as an indirect subcooler that the system of condenser and subcooling would not require an even larger Luftanströmfläche than that which is given in the existing, conventional subcooling, whereby additional air requirements and space requirements can be avoided.

The inventive heat transfer device or the subcooling can be structurally integrated into the capacitor.

Preferably, the embodiment is selected as an indirect subcooler, which ensures that does not have to be expected with a noticeably increased, dynamic driving unwanted weight in front of the front axle.

Thus, according to an advantageous development of the invention, it is provided that the heat transfer device with indirect subcooling has a thermoelectric liquid-liquid heat exchanger arranged in the liquid high-pressure line. As a result, a particularly compact design can be achieved, which results inter alia in the heat transfer to the cooling liquid in comparison to the heat transfer to the ambient air significantly higher alpha values. This also allows a denser packing of the thermoelectric elements or of the Peltier elements.

In the embodiment as an indirect subcooler, a low-temperature cooling circuit is further provided as a heat sink for the thermoelectric elements. Conveniently, a cooling circuit already present on vehicles with an indirect capacitor ("indirect converter") (ICON) and / or with indirect charge air cooling and / or with low-temperature cooling of electronic components can be used for this purpose. When the invention is used with an indirect capacitor (ICON), this advantageously results, as already mentioned above, in that the thermoelectric subcooler according to the invention can be integrated into the assembly with the capacitor with little effort. This is made possible, in particular, by virtue of the fact that the two functionalities of the refrigeration circuit and of the refrigeration circuit can work with the same fluids.

Further advantageous embodiments are described by the following description of the figures and by the subclaims.

Brief description of the drawings

The invention will be explained in more detail on the basis of at least one embodiment with reference to the drawings. Show it:

1 a first embodiment of a refrigeration system according to the invention, which has a thermoelectric subcooler,

2 a further embodiment of a refrigeration system according to the invention, which has a thermoelectric subcooler, which is structurally integrated into a capacitor,

3 a further embodiment of a refrigeration system according to the invention, which has an indirect thermoelectric subcooler, and

4 Yet another embodiment of a refrigeration system according to the invention, which has a structurally integrated in a capacitor, indirect thermoelectric subcooler.

Preferred embodiment of the invention

The 1 shows a first embodiment of the refrigeration system according to the invention 10 , The refrigeration system 10 is exemplified as a vehicle air conditioning system. However, the invention is not limited thereto. The refrigeration system 10 has a refrigerant circuit in which an evaporator 1 , a compressor 2 , a capacitor 3 , and an expansion device 4 are arranged, which are traversed by a refrigerant. As indicated by arrows in the drawing, both the capacitor are in operation 3 as well as the evaporator 1 in a passing stream of air. This is due to the prevailing at the components temperature gradient with respect to the environment at the evaporator 1 Heat from the air is added to the refrigerant, whereas at the condenser 3 Heat is released from the refrigerant to the air. To sustain this process is by means of a compressor 2 condenses the heated refrigerant in the evaporator, including mechanical Work must be expended. In the embodiment shown here, the compressor is a belt drive 9 powered by an engine crankshaft 8th is connected. After liquefaction of the refrigerant has taken place in the condenser, the refrigerant passes through the expansion device 4 , For example, an expansion valve, and relaxed by the coolant line 5 back to the evaporator 1 directed.

To increase the efficiency of the refrigeration process is in one between the condenser 3 and the expansion device 4 arranged heat transfer device 7 The refrigerant further withdrawn heat, so that the refrigerant comes in the state of a supercooled liquid. In this case, the heat transfer device in the first embodiment of the invention is a thermoelectric subcooler 7 and has a thermoelectric element 14 or a Peltier element. The Peltier element is powered by DC 6 operated so that it transports heat from the subcooling line to the outside.

Thanks to the invention can advantageously be used for excess electrical energy from the motor vehicle, for example from a recuperation device, and an increased cooling capacity can be switched on if necessary.

Like in the 1 is shown is the heat transfer device 7 or the direct thermoelectric subcooler arranged as a separate component in the motor vehicle.

According to another embodiment, for example the in 2 shown embodiment, the heat transfer device 7 also be structurally integrated into the capacitor.

Both according to 1 as well as according to 2 become the heat transfer devices 7 directly cooled by means of air.

The heat transfer device 7 can, as already mentioned, for example, be operated by means of Rekuperationsenergie. If, however, at a time no Rekuperationsenergie for the heat transfer device 7 is available, the Peltier elements of the heat transfer device can alternatively be acted upon in accordance with a sufficient, but comparatively minor continuous current, which leads to an increase in the effective thermal conductivity of the Peltier elements and thus to a better passive cooling performance on the assumption of a suitable Vorlegenden temperature gradient. Alternatively or additionally, recourse is sometimes made to a still existing conventional cooling section.

In 3 is another embodiment of a refrigeration system according to the invention 12 shown, wherein a heat transfer device 18 is designed here as an indirect thermoelectric subcooler. This is the heat transfer device 18 connected to both the refrigerant circuit and with a low-temperature refrigerant circuit. Like in the 3 shown becomes the indirect capacitor 15 flows through in each case in the opposite direction from the refrigerant and the coolant, whereby an effective heat dissipation can be achieved. The coolant flows through the coolant line 17 in a low temperature circuit cooler 16 cooled with air. Then the coolant flows, as in the 3 shown, on to the heat transfer device 18 which acts as an indirect subcooler. In this case, the coolant temperature is lower than the refrigerant temperature, and the heat transfer device 18 is passed through by both the coolant and the refrigerant in each case the same direction. As a result, the temperatures of the refrigerant and the coolant can be equalized, whereby an efficient cooling and heat removal by means of the thermoelectric elements 14 be achieved. Further, the heat transfer device 18 additionally cooled with incoming air.

In the 4 embodiment of the invention shown differs from the in 3 shown embodiment in that the designed as an indirect thermoelectric subcooler heat transfer device 18 according to 4 in the indirect capacitor 15 structurally integrated.

Further, the heat transfer device 18 Here, as well as the indirect condenser, by the two working fluids (coolant, refrigerant) flowed through in opposite directions. The working fluids may be the same in each case according to embodiments of the invention, different fluids being selected according to other embodiments.

In the 4 embodiment shown has the particular advantage that it can be made very compact, for example, when according to the invention, a thermoelectric liquid-liquid heat exchanger is used.

One skilled in the art will recognize that the invention is not limited to the particular embodiments discussed herein, but instead solely by the scope of protection defined in the appended claim. Thus, contrary to the embodiments shown above, various extensions, changes, and alternatives are possible. For example, in certain embodiments, the invention is not applied in vehicle air conditioners, but in airplanes, ships, and cold rooms where the heat transfer device of the present invention with the thermoelectric elements can be conveniently operated by excess electrical energy.

Claims (10)

Refrigeration system ( 10 . 11 . 12 . 13 ), in particular a vehicle air conditioning system, with a refrigerant circuit comprising an evaporator ( 1 ), a compressor ( 2 ), a capacitor ( 3 . 15 ) and an expansion device ( 4 ), and with a heat transfer device ( 7 . 18 ), one in front of the expansion device ( 4 ) arranged under cooling passage for cooling a refrigerant before entering the expansion device ( 4 ), characterized in that the heat transfer device ( 7 . 18 ) one or more thermoelectric elements connected to the subcooling section ( 14 ), in particular Peltier elements having. Refrigeration system ( 10 . 11 . 12 . 13 ) according to claim 1, characterized in that the heat transfer device ( 18 ) in the condenser ( 3 . 15 ) is structurally integrated. Refrigeration system ( 10 . 11 . 12 . 13 ) according to claim 2, characterized in that the heat transfer device ( 7 . 18 ) comprises a arranged in a high-pressure liquid line thermoelectric liquid-liquid heat exchanger. Refrigeration system ( 10 . 11 . 12 . 13 ) according to one of the preceding claims, characterized in that the compressor ( 2 ) is designed as an electric compressor or as a belt-driven compressor. Motor vehicle, in particular hybrid or micro hybrid vehicle, with a refrigeration system ( 10 . 11 . 12 . 13 ) according to any one of the preceding claims. Motor vehicle according to claim 5, further comprising a Rekuperationseinrichtung for obtaining and storing electrical energy by means of a coupled to a drive train of the motor vehicle electric generator, and coupled to the Rekuperationseinrichtung energy storage device, such as a lithium-ion battery or a lead-acid battery for supply of the thermoelectric element ( 14 ) is arranged. Motor vehicle according to claim 5 or 6, characterized in that the heat transfer device ( 7 . 18 ) as a direct subcooler ( 7 ) is configured. Motor vehicle according to claim 5 or 6, characterized in that the heat transfer device ( 7 . 18 ) as an indirect subcooler ( 18 ) is configured. Motor vehicle according to claim 8, characterized in that the heat transfer device ( 7 . 18 ) with a low-temperature coolant circuit of an indirect capacitor ( 15 ) and / or with a low-temperature coolant circuit of a charge air cooling and / or with a low-temperature coolant circuit of a low-temperature cooling for electronic components is connected. Method for operating the refrigeration system installed in a motor vehicle ( 10 . 11 . 12 . 13 ) according to one of claims 1 to 4, characterized in that the supply of the thermoelectric elements ( 14 ) by means of a control and monitoring device of the refrigeration system ( 10 . 11 . 12 . 13 ) is regulated such that if no additional excess electrical power from other vehicle units for setting an active cooling of the subcooling line for the thermoelectric elements ( 14 ) is available at a suitable temperature gradient in the thermoelectric elements ( 14 ) is carried out to increase their thermal conductivity sufficient energization.

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