DE102008028066B4 - Method for operating a stationary air conditioning system in a vehicle and vehicle stationary air conditioning system - Google Patents

Abstract

Method for operating a stationary air conditioning system in a vehicle using two coolant circuits (1, 2) connected by heat exchangers and at least one cold storage unit (12) that can be charged and discharged, at least during vehicle standstill phases, wherein a first coolant circuit (1) comprises at least one refrigerant compressor (3), a condenser (4), an expansion valve (5) and an evaporator (6) and a second coolant circuit (2) comprises at least one heat exchanger (8) containing the evaporator (6) of the first coolant circuit (1) for absorbing cold and a liquid/air heat exchanger (9') for releasing air conditioning cooling,
characterized by
that the refrigerant compressor (3) is driven electrically by means of low voltage independently of the vehicle drive motor in order to charge the cold storage unit (12) when sufficient electrical energy is available and to provide air conditioning cooling at the liquid/air heat exchanger (9') when the cold storage unit (12) is discharged during standstill phases of the vehicle drive,
wherein the second coolant circuit (2) is part of the cold storage unit (12) and is supplied by a second coolant medium (2A) independent of a first coolant medium (1A) of the first coolant circuit (1) and that both coolant circuits (1, 2) in the area of the evaporator (6) of the first coolant circuit (1) and the heat exchanger (8) of the second coolant circuit (2) containing it, directly deliver cold to the liquid/air heat exchanger (9').

Description

The invention relates to a method for operating a stationary air conditioning system in a vehicle according to the preamble of claim 1 and to a vehicle stationary air conditioning system according to the preamble of claim 7. Accordingly, the invention is based on a known operating mode of stationary air conditioning systems in which two coolant circuits connected by heat exchangers and at least one cold storage device that can be charged and discharged during vehicle standstill phases are used, and in which a first coolant circuit comprises at least a coolant compressor, a condenser, an expansion valve and an evaporator, and a second coolant circuit comprises at least a heat exchanger containing the evaporator of the first coolant circuit for absorbing cold, as well as a liquid/air heat exchanger for delivering air conditioning cooling and, optionally, a coolant pump.

The challenge with stationary vehicle air conditioning systems is to provide sufficiently cool air (air conditioning air) during breaks, such as rest stops, even in relatively warm and/or humid conditions. The energy required to operate such stationary vehicle air conditioning systems is considerable, typically ranging from 1 to 5 kWh.

• Eine bekannte integrierte Fahr- und Standklimaanlage besteht aus zwei Kreisläufen, nämlich einem konventionellen Kältekreislauf zur Kälteerzeugung und einem Kältetransportkreislauf, zur Kälte-Verteilung. Der konventionelle Kältekreislauf ist z. B. für das Kältemittel R134a ausgelegt; seine Komponenten sind ein Kältemittel-Kompressor, ein Kältemittel-Kondensator, ein Kältemittel-Expansionsventil und ein Verdampfer. In diesem Verdampfer wird aber nicht Luft, wie bei einer üblichen (Fahr-)Klimaanlage für Fahrzeuge - sondern ein Kälteträger, wie eine Wasser-Glysantin-Mischung abgekühlt. Der Verdampfer ist die Schnittstelle zwischen den beiden Kühlmittel-Kreisläufen. Der zweite Kühlmittel-Kreislauf setzt sich zusammen aus der erwähnten Verdampfer-Schnittstelle sowie einem Kältespeicher, einem Klimagerät und einer Verteil- und Regeleinheit für den Kälteträger. Das sogenannte Klimagerät wird an einem beliebigen, von dem Verdampfer entfernten Punkt angeordnet, um dort aus dem zirkulierenden zweiten Kühlmittel-Kreislauf Klimatisierungskälte an die zu kühlende Luft abzugeben. Hierfür wird ein Flüssig/Luft-Austauscher verwendet. Die Verteil- und Regeleinheit für das Kreislaufmedium des zweiten Kühlmittel-Kreislaufes kann wahlweise mit dem Flüssig/Luft-Wärmeaustauscher oder mit einem Kältespeicher verbunden werden. Der Kältespeicher besteht aus einem isolierten Gehäuse und einer Anzahl von Speicherelementen mit der dazwischen liegenden Strömungskanälen für Kälteträger. Der Kälteträger kann ein Gemisch aus Wasser und z. B. Glysantin sein.
• Durch die guten Wärmeübertragungseigenschaften zwischen dem aus Speicherelementen und dazwischen liegenden Strömungskanälen für Kälteträger bestehenden Kältespeicher und dem Verdampfer des ersten Kühlmittel-Kreislaufes, kann eine Kapazität von 5 kWh Kälteleistung in vergleichsweise kurzer Zeit in den Kältespeicher geladen werden. Wenn gleichzeitig zu einem solchen Ladevorgang die Kabinen-Klimatisierung erfolgt oder fortgesetzt wird, dauert die Kältespeicher-Aufladung entsprechend länger, z. B. die dreifache Zeit. Bei dieser bekannten Fahrzeug-Standklimaanlage zirkuliert bei Klimatisierung während der Fahrt der Kälteträger des zweiten Kühlmittel-Kreislaufes zwischen Verdampfer und Klimagerät. Im Flüssig/Luft-Wärmeaustauscher des Klimagerätes wird die Kabinenluft (Frischluft oder Umluft) abgekühlt und entfeuchtet. Bei dieser Betriebsart, die auch als Erhaltungsklimatisierung (ohne das „Herunterkühlen“ des Fahrerhauses) bezeichnet wird, liefert der kontinuierlich arbeitende Verdampfer in der Regel mehr Kälteenergie als für die Klimatisierung der Kabine erforderlich ist. Der nicht benötigte Teil der Kälteleistung wird zum Aufladen des Kältespeichers genutzt.
• Bei extremen Anforderungen an die Klimatisierung kann der Kältespeicher auch zur Erhöhung der Kühlleistung eingesetzt werden. Der Kälteträger wird dann nach dem Verdampfer im Kältespeicher weiter abgekühlt und erst dann zum Klimagerät in der Fahrzeugkabine geleitet.- Eine derartige kombinierte Fahr- und Standklimaanlage für Fahrzeuge ist außerordentlich komplex, auch was die Steuerung und die Kälteträgerverteilung anbelangt.

Commercially available vehicle air conditioning systems are typically designed to function as well, allowing them to maintain a comfortable climate in the driver's cabin while driving. This involves combining both systems and providing the energy required to drive the refrigeration compressor of a refrigerant circuit through mechanical coupling to the vehicle's engine. When the engine is running, the refrigeration compressor is mechanically driven by the engine. To bridge longer periods of inactivity, the cooling generated during driving is stored for later use. This is achieved as follows:

• A well-known integrated vehicle and stationary air conditioning system consists of two circuits: a conventional refrigeration circuit for generating the cooling and a refrigeration transfer circuit for distributing the cooling. The conventional refrigeration circuit is designed for refrigerant R134a, for example; its components are a refrigerant compressor, a refrigerant condenser, a refrigerant expansion valve, and an evaporator. However, unlike a typical vehicle air conditioning system, this evaporator does not cool air, but rather a refrigerant, such as a water-antifreeze mixture. The evaporator serves as the interface between the two refrigerant circuits. The second refrigerant circuit comprises the aforementioned evaporator interface, a cold storage unit, an air conditioner, and a distribution and control unit for the refrigerant. The air conditioner is positioned at a point remote from the evaporator to transfer cooling from the circulating second refrigerant circuit to the air being cooled. A liquid-to-air heat exchanger is used for this purpose. The distribution and control unit for the circulating medium of the second coolant circuit can be connected either to the liquid-to-air heat exchanger or to a cold storage unit. The cold storage unit consists of an insulated housing and a number of storage elements with flow channels for the refrigerant between them. The refrigerant can be a mixture of water and, for example, antifreeze.
• Due to the efficient heat transfer properties between the cold storage unit (consisting of storage elements and intervening flow channels for the refrigerant) and the evaporator of the first refrigerant circuit, a cooling capacity of 5 kWh can be charged into the cold storage unit in a relatively short time. If cabin air conditioning is running or continues during such a charging process, the cold storage unit charging takes correspondingly longer, e.g., three times as long. In this known stationary vehicle air conditioning system, when air conditioning is operating while driving, the refrigerant of the second refrigerant circuit circulates between the evaporator and the air conditioning unit. In the liquid-to-air heat exchanger of the air conditioning unit, the cabin air (fresh air or recirculated air) is cooled and dehumidified. In this operating mode, also known as maintenance air conditioning (without "cooling down" the cab), the continuously operating evaporator typically delivers more cooling energy than is required for cabin air conditioning. The unused portion of the cooling capacity is used to charge the cold storage unit.
• In cases of extreme air conditioning demands, the cold storage unit can also be used to increase cooling capacity. The refrigerant is then further cooled in the cold storage unit after passing through the evaporator, and only then is it directed to the air conditioning unit in the vehicle cabin. Such a combined driving and stationary air conditioning system for vehicles is exceptionally efficient. complex, also with regard to the control system and the distribution of the refrigerant.

Examples of stationary air conditioning systems are from the DE 10 2004 002 715 A1 and the DE 198 60 057 A1 known.

Based on this, the invention aims to simplify the design of stationary vehicle air conditioning systems and to improve the energy resources for cabin air conditioning when the vehicle's engine is not running. Such stationary vehicle air conditioning systems can, of course, cool various areas of a vehicle, not just the passenger compartment.

To solve this problem, a method with the features of claim 1 and a device with the feature of claim 7 are proposed. Accordingly, it is provided that the refrigerant compressor of the first coolant circuit is driven independently of the vehicle's drive motor, namely electrically by means of low voltage, in order to charge the cold storage unit when sufficient electrical energy is available and to provide air conditioning cooling at the liquid/air heat exchanger when the cold storage unit is discharged during periods when the vehicle's drive system is stationary. Furthermore, it can be provided that a refrigerant pump of the second coolant circuit, if used, is electrically driven by means of low voltage, particularly when the refrigerant compressor is stationary, in order to discharge the cold storage unit via the liquid/air heat exchanger and – if desired – to provide air conditioning cooling from the first coolant circuit at the liquid/air heat exchanger. The invention is therefore based on the basic idea of providing two energy reservoirs for cooling when the vehicle is stationary: namely, the rechargeable cold storage unit on the one hand and, on the other hand, the on-board battery for electrical voltage from the vehicle, through which, even when the cold storage unit is discharged, electrical energy for air conditioning cooling is still provided via the refrigerant compressor despite the vehicle being stationary.

The invention allows the cold storage unit to be significantly smaller compared to known vehicle stationary air conditioning systems, without compromising cooling performance during the occasional extended cooling phases. This reduction in size also decreases the weight of the cold storage unit and allows it to be positioned directly at the point of air conditioning delivery, thus improving compactness, particularly as described below. Cold storage capacities of approximately 2 kWh are sufficient for a large number of applications. The accumulator batteries are protected against deep discharge by suitable, known battery monitors, as is generally the case. The use of purely electrical drive energy for refrigerant compressors is therefore not possible. WO 85/03603 While the principle is generally known, the solution used there is intended for cooling coolers with eutectic storage plates. These coolers continue to operate at a significantly higher temperature level after the cold storage unit is discharged than when fully charged. Such temperature differences are fundamentally unacceptable for air conditioning. Furthermore, eutectic storage plates are unsuitable for transferring cold air to the conditioned air via liquid/air heat exchangers in a vehicle's stationary air conditioning system.

The invention can now be implemented in various ways. According to a first preferred operating mode, the second coolant circuit, driven by a refrigerant pump, transfers stored and/or in-situ generated cooling for immediate use to the liquid/air heat exchanger via a second circuit medium that is independent of the first circuit medium of the first coolant circuit and of the cold storage unit. Unlike the aforementioned vehicle stationary air conditioning systems, the cold storage unit's contents are thus kept separate from the circuit medium of the second coolant circuit. This makes it possible to keep the operating volume of the second coolant circuit extremely small and to optimally adapt the (second) circuit medium to the specific characteristics of this circuit and, in particular, to favorable material pairings in the area of the liquid/air heat exchanger. Therefore, any cold storage medium, including solid cold storage media, can be used, and, in particular, the quantity and weight of the storage medium can be optimized. Furthermore, a distribution and control unit for the second circulating medium can be omitted or significantly simplified. Such a method for operating a vehicle stationary air conditioning system and a corresponding vehicle stationary air conditioning system is of independent inventive significance even without the characterizing features of claim 1. Nevertheless, a separate heat exchanger, namely for charging and discharging the cold storage unit, can be omitted if the cold storage unit is combined with the evaporator of the first coolant circuit and with the heat exchanger of the second coolant circuit, which contains the evaporator for cold absorption, to form a heat exchange unit to be described in more detail below.

Furthermore, it is planned that the second coolant circuit will be part of the cold storage system. is and is traversed by a second circulating medium independent of the cooling medium of the first coolant circuit, and that in the area of the evaporator of the first coolant circuit and the heat exchanger of the cold storage unit containing it, cold is transferred directly to the liquid/air heat exchanger.

The cold storage substance can alternatively remain stationary within the cold storage unit. This eliminates the need for a dedicated refrigerant circuit for transporting the cold to the liquid-to-air heat exchanger used for air conditioning. The entire heat exchanger assembly can be installed directly at the point of use for cooling, similar to a conventional air conditioner. The cold storage unit adds a comparatively small amount of weight to the heat exchanger, as portions of the circulating cold storage medium can be stored in a thermally insulated auxiliary storage tank located away from the cooling point. Connecting lines between the auxiliary storage tank and the cold storage unit can be easily installed and thermally insulated. This results in a triple heat exchange process, and a refrigerant distribution and control unit, as described in the aforementioned prior art, is completely unnecessary. During operating phases without charging or discharging the cold storage unit, the refrigerant pump in this circuit simply needs to be switched off. The amount of cold storage medium contained in the combined liquid/air heat exchanger acts as a buffer, which evens out the cold absorption of the integrated heat exchanger, and in particular its cold emission, in a manner that is comfortable for the vehicle user. The second embodiment is of independent inventive significance, even apart from the characterizing features of claim 1.

If the cold storage unit is combined with the evaporator of the first coolant circuit and with the heat exchanger containing the evaporator for cold absorption, this is, as already explained, particularly advantageous from a thermal engineering and circuit engineering perspective and also allows for a reduction in the number of components as well as comparatively flexible placement in the vehicle and a compact design. This method and a corresponding integrated heat exchanger are also of independent inventive significance even without the characterizing features of claim 1.

If a tube-in-tube system is used for the evaporator and the heat exchanger containing it, a highly efficient heat exchange between the first refrigerant circuit, the second refrigerant circuit, and/or the cold storage unit and the liquid/air heat exchanger can be achieved in a particularly simple manner. This is because one of the heat exchange media is inserted between the other two heat exchange media, allowing for the selective exchange of cooling energy between the media via the shortest possible path. Relatively small quantities of cooling media may be sufficient for effective heat exchange. Such an integrated heat exchanger is of independent inventive significance, even without the characterizing features of claim 1.

The aforementioned components, as well as those claimed and described in the exemplary embodiments, to be used according to the invention, are not subject to any special exceptional conditions with regard to their size, shape, material selection, and technical design, so that the selection criteria known in the field of application can be applied without restriction. Further details, features, and advantages of the subject matter of the invention will become apparent from the dependent claims and from the following description of the associated drawing and table, in which—by way of example—an exemplary embodiment of a vehicle stationary air conditioning system is shown.

• 1 zeigt als Blockschaltbild die wesentlichen Elemente einer ersten Ausführungsform einer Fahrzeug-Standklimaanlage;
• 2 zeigt ein Blockschaltbild die wesentlichen Elemente einer zweiten Ausführungsform einer Fahrzeug-Standklimaanlage;
• 3 zeigt in Vertikalschnittdarstellung eine Prinzipdarstellung eines integrierten Wärmeaustauschers und Kältespeichers für die Ausführungsform nach 1 sowie
• 4 zeigt in Vertikalschnittdarstellung eine Prinzipdarstellung eines integrierten Wärmeaustauschers und Kältespeichers für die Ausführungsform nach 2

The drawing shows

• 1 The block diagram shows the essential elements of a first embodiment of a vehicle stationary air conditioning system;
• 2 A block diagram shows the essential elements of a second embodiment of a vehicle stationary air conditioning system;
• 3 The figure shows a schematic representation of an integrated heat exchanger and cold storage unit for the embodiment according to [reference missing]. 1 as well as
• 4 The figure shows a schematic representation of an integrated heat exchanger and cold storage unit for the embodiment according to [reference missing]. 2

The in 1 The vehicle stationary air conditioning system 10, shown in excerpts as a schematic diagram, has a first refrigerant circuit 1 and a second refrigerant circuit 2 connected to it. The first refrigerant circuit 1, filled, for example, with refrigerant R134a, comprises at least one, preferably controllable, refrigerant compressor 3, a condenser 4, an expansion valve 5, and an evaporator 6, as well as conventional piping that completes the circuit. The second, filled with water and optionally a The refrigerant circuit 2, filled with a known medium and used to lower the freezing temperature, comprises at least one refrigerant pump 7, a heat exchanger 8 containing the evaporator 6 of the first refrigerant circuit 1 for absorbing cold, and a liquid/air heat exchanger 9 for transferring cooling to the room air by means of an evaporator fan 11. The arrows within the two refrigerant circuits 1 and 2 indicate the flow direction of the first circuit medium (R134a) and the second circuit medium (water). The refrigerant compressor 3 is operated exclusively electrically with 24 volts direct current, thus being mechanically independent of the vehicle's drive motor. The electrical drive voltage can also be 12, 36, or even 48 volts. In this context, "low voltage" as used in the invention refers to an electrical voltage, particularly a direct current voltage, between approximately 10 and 50 volts.

In the first coolant circuit 1, the cooling required for the air conditioning system is generated, along with a surplus of cooling energy. This allows not only for maintenance air conditioning and cooling of at least one compartment in the vehicle, even under strong solar radiation, but also provides sufficient cooling energy to charge a cold storage unit. A corresponding cold storage unit 12 is also located in the unit, which also houses the evaporator 6 and heat exchanger 8. A corresponding integrated arrangement is described in connection with 3 will be explained.

In the second coolant circuit 2, a fluid refrigerant, such as water, is circulated between the unit consisting of evaporator 6, heat exchanger 8, and cold storage tank 12, and the liquid-to-air heat exchanger 9 by means of a refrigerant pump 7 designed as a water pump. With sufficient thermal insulation of the circuit lines and the two other components, the cooling loss due to the recirculation is minimal. By switching off the electrically operated water pump, the cooling loss in the second coolant circuit can be reduced to almost zero if required. If, with the water pump running, room air is then passed through the liquid-to-air heat exchanger 9 by means of a known evaporator fan 11, the cooling required for air conditioning is extracted from the second coolant circuit 2. Suitable piping, in particular air distribution piping 13 for air conditioning air, which may already be present in the vehicle, transports the cooling air to the preferred outlet locations. However, the air conditioning air can also exit directly from an air conditioning unit known per se, consisting of a liquid/air heat exchanger 9, evaporator fan 11 and air distribution medium 13, at the preferred central location for air conditioning air.

A preferred operating mode of this embodiment is as follows: With sufficient electrical voltage supply in the vehicle, i.e., preferably with the vehicle's drive engine running, an alternator (not shown in the drawing) generates sufficient direct current (DC) by means of the running vehicle drive engine to drive the refrigerant compressor 3, which in the illustrated and thus preferred embodiment is designed as a controllable 24V DC compressor. This occurs completely independently of any vehicle air conditioning system installed in the vehicle and also independently of the mechanical vehicle drive, i.e., purely electrically. The compressor runs while the vehicle, particularly a commercial vehicle, is in motion and uses the energy supplied by the alternator to supply the refrigerant in the evaporator 6 and the cold storage unit 12 preferably integrated therein. Various operating modes are possible during this phase of refrigeration supply. Firstly, the cooling energy can be immediately transferred via the second refrigerant circuit to the consumer, the air conditioning unit, consisting of a liquid/air heat exchanger 9, evaporator fan 11, and air distribution unit 13. If there is a particularly high demand for cooling, it is possible, in extreme cases, that not only is the cold storage unit not charged, but any residual cooling energy already stored in it is also used up. However, the second refrigerant circuit can also be switched off, so that all the cooling energy is supplied to the cold storage unit 12. The stored cooling energy is then available to the vehicle's stationary air conditioning system. If this system is now switched on to cool the cab during a break in driving or to keep it cool, the stored cooling energy is first drawn from the cold storage unit. Only the second refrigerant circuit is active during this process. The first refrigerant circuit is not used. Electrical power consumption is limited to the operation of the refrigerant pump 7 and the evaporator blower 11. If the cooling energy from the cold storage unit is depleted and the vehicle's drive engine is still off, the refrigerant compressor 3 switches on to meet the current cooling demand. The compressor draws the required energy from the vehicle battery. The cold storage unit is not recharged during this time, as the supplied cooling energy is transferred directly via the primary circuit (first refrigerant circuit) within the unit consisting of the evaporator 6, heat exchanger 8, and cold storage unit 12. is supplied to the secondary circuit (second coolant circuit).

The vehicle's stationary air conditioning system utilizes two energy storage devices when the vehicle is stationary: firstly, the cold storage unit 12, provided it is charged; and secondly, the vehicle battery, which powers the electrically driven refrigerant compressor. The cooling time can therefore easily last at least six to eight hours.

Out of 3 is one for the embodiment according to 1 A particularly suitable integrated heat exchanger is shown schematically. It comprises, firstly, a tube-in-tube cooling coil arrangement 14 and, secondly, a storage container 15 filled with a cold-storing substance 16 and preferably thermally insulated on the outside, into which the tube-in-tube cooling coil arrangement 14 is immersed. The circulating medium (R134a) of the primary circuit (first refrigerant circuit) flows through an outer tube 14A. The outer tube 14A contains the evaporator 6. The circulating medium of the secondary circuit (second refrigerant circuit), consisting, for example, of water and anti-caking agents, flows through an inner tube 14B. The cold-storing substance 16 in the storage container 15 can, for example, contain a water/anti-caking agent mixture, which is generally not circulated and is in liquid form in the preferred temperature range between +1° and -5°. Semi-solid and solid cold-storing substances can also be used. Outside the storage tank 15, the inner tube 14B extends from the outer tube 14A and is arranged separately. Inside the storage tank 15, the inner tube 14B serves as the heat exchanger 8, containing the evaporator 6 (on its outer surface), between the primary and secondary circuits.

The cooling medium 1A of the primary circuit transfers its cooling energy via indirect heat transfer not only to the cooling medium 2A of the secondary circuit, but also to the cold storage substance 16. It utilizes the outer tube 14A as a heat exchanger. In this way, cooling can be efficiently transferred to both the secondary circuit and the cold storage unit for charging.

When the cold storage unit is discharged, the pipe wall of the outer pipe 14A, which is inserted between the cold-storing substance 16 and the secondary circuit, together with the quantity of first cooling medium 1A enclosed by the outer pipe 14A, has a compensating effect on the cooling output to the cooling medium 2A of the second coolant circuit, without, however, hindering the discharge of the cold storage unit.

According to the in 2 the second embodiment shown and the special embodiment according to 4 , the first coolant circuit 1 is essentially identical to the first embodiment.

• Ein zur Verwendung mit dem zweiten Ausführungsbeispiel bevorzugter integrierter Wärmeaustauscher wird jetzt im Zusammenhang mit 4 erläutert. Dessen Aufbau stimmt insoweit mit dem Aufbau nach 3 überein, dass ein Außenrohr 14A einer Rohr-in-Rohr-Kühlschlangenanordnung 14 das Kühlmedium 1A des Primärkreislaufes, z. B. R134a, führt, wobei in seinem Inneren ein, insbesondere koaxial verlaufendes Innenrohr 14B angeordnet ist, innerhalb dessen das zweite Kühlmedium 2A, z. B. Wasser, gegebenenfalls mit einem die Erstarrungstemperatur absenkenden Zusatz, wie Antifugen, versehen ist.

The only difference is that the integrated heat exchanger unit, consisting of evaporator 6, heat exchanger 8, and liquid/air heat exchanger 9', is constructed differently, as explained below. In the second embodiment, the cooling is transferred directly to a liquid/air heat exchanger 9' integrated into the evaporator and heat exchanger 8, as described below. Therefore, a simple transport circuit, as in the first embodiment, is not used. However, a cold storage circuit may be provided, as described below.

• An integrated heat exchanger preferred for use with the second embodiment is now described in connection with 4 explained. Its structure corresponds insofar as it does not correspond to the structure according to 3 agrees that an outer tube 14A of a tube-in-tube cooling coil arrangement 14 carries the cooling medium 1A of the primary circuit, e.g. R134a, wherein an inner tube 14B, in particular coaxially extending, is arranged inside it, within which the second cooling medium 2A, e.g. water, is optionally provided with an additive to lower the freezing temperature, such as anti-caking agents.

In contrast to the integrated heat exchanger according to 3 A storage tank accommodating the pipe-in-pipe cooling coil arrangement 14 is not provided. Instead, a cold-storing substance 16 circulates in the inner pipe 14B by gravity flow or, as not shown, with the assistance of a fluid pump. Outside the actual heat storage unit is an auxiliary storage unit 12', which receives the inlet and outlet openings of the inner pipe 14B at spaced-apart ends. The second "coolant circuit 2" thus comprises, in addition to the inner pipe 14B, any connecting lines and the preferably externally located auxiliary storage unit 12', as well as optionally a circulation pump. The inner pipe 14B is therefore simultaneously part of a storage tank 15 for a cold-storing, preferably, but not necessarily, fluid cold-storing substance 16. However, solid cold-storing substances can also be provided in the inner pipe 14B.

The pipe-in-pipe cooling coil arrangement 14 is provided, in a manner known per se, with a plurality of closely spaced fins 17 for heat exchange with the air conditioning air. The fins 17 are part of the liquid/ Air heat exchanger 9' for cooling the air conditioning air and allow passage for air conditioning air.

The operating mode of the integrated heat exchanger according to 4 The outer pipe 14A contains the evaporator of the primary circuit and transfers cold to the fins 17 on its outer surface for transport by the air conditioning air. Cold is also transferred to the inner pipe 14B, which is part of the cold storage unit 12 and releases cold to the cold storage substance 16 when sufficient cooling energy is available or when there is no demand for cold at the fins 17 (an evaporator fan is switched on).

When the vehicle's drive motor is not running, cooling can now be drawn from the storage tank 15 until it is completely discharged. If cooling is still required afterwards, the refrigerant compressor can be powered by electricity from the vehicle's battery, as also explained in the first embodiment.

REFERENCE MARK

1

first coolant circuit

1A

Cooling medium

2

second coolant circuit

2A

Cooling medium

3

Refrigerant compressor

4

capacitor

5

Expansion valve

6

evaporator

7

Refrigerant pump

8

Heat exchanger

9

Liquid/air heat exchanger

9'

Liquid/air heat exchanger

10

Vehicle stationary air conditioning

11

Evaporator blower

12

Cold storage

12'

Additional storage

13

Air distribution medium

14

Pipe-in-pipe cooling coil arrangement

14A

outer pipe

14B

Inner tube

15

Storage container

16

cold-storing substance

17

slats

Claims (10)

A method for operating a stationary air conditioning system in a vehicle using two coolant circuits (1, 2) connected by a heat exchanger and at least one chargeable and, at least during vehicle standstill phases, dischargeable cold storage unit (12), wherein a first coolant circuit (1) comprises at least one refrigerant compressor (3), a condenser (4), an expansion valve (5), and an evaporator (6), and a second coolant circuit (2) comprises at least one heat exchanger (8) containing the evaporator (6) of the first coolant circuit (1) for absorbing cold, and a liquid/air heat exchanger (9') for delivering air conditioning cooling, characterized in that the refrigerant compressor (3) is driven electrically by low voltage independently of the vehicle's drive motor in order to charge the cold storage unit (12) when sufficient electrical energy is available and to provide air conditioning cooling at the liquid/air heat exchanger (9') when the cold storage unit (12) is discharged during standstill phases of the vehicle drive, wherein the second coolant circuit (2) is part of the cold storage unit (12) and is supplied by a second coolant medium (2A) independent of a first coolant medium (1A) of the first coolant circuit (1), and that both coolant circuits (1, 2) in the area of the evaporator (6) of the first coolant circuit (1) and the heat exchanger (8) of the second coolant circuit (2) containing it, directly deliver cold to the liquid/air heat exchanger (9'). Procedure according to Claim 1 , in which the cold storage unit (12) is not permeated by the second cooling medium (2A), but the second cooling medium (2A) remains stationary. Procedure according to one of the Claims 1 or 2 , characterized in that the cold storage unit (12) is combined with the evaporator (6) of the first coolant circuit (1) and with the heat exchanger (8) of the second coolant circuit (2) which contains the evaporator (6) for the purpose of cold absorption to form a heat exchanger unit. Procedure according to one of the Claims 1 until 3 , characterized by the use of a tube-in-tube system for the evaporator (6) and the heat exchanger (8) containing it. Vehicle stationary air conditioning system with two coolant circuits (1, 2) connected by a heat exchanger and with at least one rechargeable and dischargeable cold storage unit (12), wherein a first coolant circuit (1) comprises at least one refrigerant compressor (3), a condenser (4), an expansion valve (5) and an evaporator (6), and wherein a second coolant circuit (2) comprises at least one heat exchanger (8) containing the evaporator (6) of the first coolant circuit (1) for absorbing cold, as well as a liquid/air heat exchanger (9') for delivering air conditioning cooling, characterized in that the refrigerant compressor (3) is mechanically independent of the vehicle drive motor and can be electrically operated by means of low voltage in order to charge the cold storage unit (12) when sufficient electrical energy is available and to provide air conditioning cooling at the liquid/air heat exchanger (9') when the cold storage unit (12) is in use during periods when the vehicle drive is stationary is discharged, wherein the second coolant circuit (2) is part of the cold storage unit (12) and receives a second coolant medium (2A) independent of a first coolant medium (1A) of the first coolant circuit (1), and that both coolant circuits (1, 2) in the area of the evaporator (6) of the first coolant circuit (1) and the heat exchanger (8) of the second coolant circuit (2) containing it have heat exchangers, such as fins (17), for the direct transfer of cold to an air conditioning airflow. Vehicle stationary air conditioning system Claim 5 , characterized by a pipe-in-pipe system in which one pipe comprises the evaporator (6) of the first coolant circuit (1) and in which the other pipe receives the second cooling medium (2A) of the second coolant circuit (2) in the area of the heat exchanger (8) of the second coolant circuit (2). Vehicle stationary air conditioning system Claim 5 or 6 , characterized by an additional storage unit (12') which can be circulated through by the second cooling medium (2A) or a cold-storing substance (16) in conjunction with the cold storage unit (12). Vehicle stationary air conditioning after one of the Claims 5 until 7 , characterized in that the cold storage unit (12) is combined with the evaporator (6) of the first coolant circuit (1) and with the heat exchanger (8) of the second coolant circuit (2) which contains the evaporator (6) for the purpose of cold absorption to form a heat exchanger unit. Vehicle stationary air conditioning after one of the Claims 5 until 8 , characterized in that the evaporator (6) and the cold storage unit (12) in the area of the liquid/air heat exchanger (9') are designed as a pipe-in-pipe system. Vehicle stationary air conditioning after one of the Claims 5 until 9 , characterized in that the cold storage unit (12) is not permeated by the second cooling medium (2A), but the second cooling medium (2A) remains stationary.