DE102007015390A1 - Method and device for cooling a cold room and refrigerated vehicle - Google Patents

Abstract

The present invention relates to an apparatus and a method for cooling at least one cold room (1) using liquefied cold gas, in particular liquid nitrogen (LIN), using a heat exchanger (2) which can be cooled by the liquefied gas (LIN) and via which outside air (AIR) can be supplied to the cooling space (1), wherein at least a part of the cooling is supplied in a first time period by supplying liquefied gas (LIN) via the heat exchanger (2) to a first outlet, in particular a spraying device (10 ), is effected in the cooling space (1) and wherein for the venting, the supply of liquefied gas (LIN) is interrupted and in a second period of time, the supply of outside air (AIR) via the heat exchanger (2). Preferably, in a third period of time, liquefied gas (LIN) is supplied to the cooling space (1) bypassing the heat exchanger (2), and the third time interval is selected as long as the heat exchanger (2) requires for defrosting. As a heat exchanger (2) is a heat storage with suitable heat capacity and surface, in particular with a coil (15), preferably made of copper, used, which successively flows through the liquefied gas (LIN) in the first period and from the outside air (AIR) in the second Period is flowed around. The invention is particularly suitable for refrigerated vehicles cooled directly with liquid nitrogen (LIN) in delivery traffic with frequent door openings, since they provide a ...

Description

The The invention relates to a method and a device for cooling a refrigerator and a refrigerated vehicle. Especially The invention relates to a method and a device for cooling a mobile refrigerator, such as a container, as well a refrigerated vehicle with such a cooling space for the Transport of goods, where the cooling by direct spraying a liquid, cryogenic gas in the refrigerator takes place and for loading and unloading a frequent opening and entering is required.

since Nitrogen is used for vehicle cooling for a long time, in particular used in vehicles with multi-chamber systems. Such a thing The method is known by the name CryogenTrans (CT). In the CT procedure Nitrogen is in liquid, cryogenic form in one Vacuum insulated storage container carried on or in the vehicle. This is used for cooling via a pipeline taken and by the autogenous pressure of the medium directly into a cold room sprayed. The process is particularly simple and insensitive to interference. Furthermore, the cooling capacity is independent of the Ambient temperature always the same. It is in principle only by the Limited passage of the spray nozzles. Therefore show CT refrigerated trucks in distribution of food be used and of course multiple door openings during cooling, have significant benefits in the quality of cooling. Especially in the Midsummer when mechanical refrigeration systems with power drops to fight on the condensers and with icing on the evaporators the CT method shows its advantages in terms of efficiency, Reliability and performance. After a door opening the target temperature is reached again within seconds.

adversely At the CT procedure is that before entering the refrigerator for safety reasons, this fully ventilated must become. This gets a lot of hot air in the necessary Refrigerator. The new cooling down happens Although very fast, but costs more energy and causes it more costs than necessary. The usual installation of cold retention systems, such as B. from a curtain, separates in CT-cooled Vehicles out, as they turn the ventilation into dangerous Would hinder the way.

From the EP 1 252 471 B1 For example, a method for keeping cold a freezer compartment of a food transport vehicle and a corresponding vehicle are known. In this case, the freezer compartment is cooled by spraying liquid nitrogen. Upon intentional opening and entering of the freezer compartment, the nitrogen supply is interrupted and liquid nitrogen is passed through a heat exchanger. A fan presses external air into the freezer compartment via the heat exchanger, which cools the air and ventilates the freezer compartment. In this case, the nitrogen passed through the heat exchanger is passed to the outside.

In another embodiment is further known while of loading and unloading nitrogen by one on the ceiling of the refrigerator arranged coil to conduct as an evaporator and then in the Dismantle environment to the refrigerator at low temperature to keep.

adversely At this state of the art is that not the full theoretical Cooling power of nitrogen can be exploited. Further is disadvantageous that the discharged into the environment cold gaseous Nitrogen can cause problems, especially if the vehicle stands in enclosed unloading stations, such as halls or garages that are a relative have small volume.

Known is also the indirect cooling, in the heat exchanger are used, the z. B. cooled with liquid nitrogen and cool the air inside a refrigerator. Aeration before entering for security reasons is not necessary then.

adversely However, in this prior art is that the aforementioned Advantages of cooling with liquid nitrogen get lost. In particular, in the summer icing of the heat exchanger by the supply of warm air with high moisture content occur.

It is therefore an object of the present invention, a method and a device for cooling at least one cooling space and a corresponding refrigerated vehicle available to provide, in which the cooling by introducing liquid cryogenic gas occurs and to enter when loading and unloading the Refrigerator a ventilation with ambient air effectively and inexpensively.

These The object is achieved by a method according to claim 1, a device according to claim 6 and a refrigerated vehicle according to claim 15 solved. Advantageous embodiments and developments, the each individually or suitably combined with each other in any suitable manner are given in the subclaims.

In the method according to the invention, a cooling space is cooled in a first period of time by supplying liquefied gas, in particular liquid nitrogen, whereby the liquefied gas is simply sprayed into the cooling space. However, the liquefied gas is first passed through a heat exchanger, which serves as a cold storage in this case, causing this heat exchanger about cooled to the temperature of the liquefied gas. When the refrigerator is to be entered by a person, the supply of liquefied gas is first interrupted and the outside air is supplied to the refrigerator for ventilation. Depending on the outside temperature, this outside air would heat up the cooling chamber relatively quickly with direct supply, which according to the invention verhin changed that the outside air is now supplied in the second period of time via the heat exchanger. In this case, this acting as a cold storage heat exchanger releases the stored in him cold relatively quickly to the supplied outside air, so that it passes only after heavy cooling in the cold room. The cold previously stored in the heat exchanger can therefore be used almost completely for further cooling of the cold room when it is ventilated to prepare for the inspection by a person. This creates an easily breathable atmosphere in the cold room, which is considerably colder than with direct ventilation.

The outside air supplied by the heat exchanger typically contains a certain amount of moisture, which leads to ice formation in the heat exchanger. For this reason, after the end of the commission of the refrigerator in a third period liquefied gas the refrigerator supplied bypassing the heat exchanger. Thereby can Cold losses due to the inspection are compensated very quickly be, but at the same time defrosted the heat exchanger can be. Accordingly, the third period of time becomes at least that long chosen, as the heat exchanger for defrosting needed.

Around the inventive method particularly advantageous to be able to use the heat exchanger as Heat storage with suitable heat capacity and surface equipped. Particularly suitable is the Use of at least one pipe coil, preferably of a copper alloy, successively from the liquefied gas in the first period flows through and from the outside air in the second period is flowed around.

The inventive method is particularly suitable when using liquid nitrogen as a coolant a refrigerator of a refrigerated vehicle with a or more cooling chambers.

A Cooling device according to the invention at least one cold room by means of a liquefied Gas has a heat-storing heat exchanger on, the at least one primary inlet and at least a primary outlet for liquefied cold gas and at least one secondary inlet and one Secondary outlet for ambient air includes. there is the primary inlet with a reservoir connectable to liquefied gas. The secondary inlet is connectable to the environment. The primary outlet and the secondary outlet is connected to the refrigerator. There are also means to shut off the primary inlet available. This equipment allows, first liquefied cold gas from a reservoir through the heat exchanger to feed into the cold room and spray in this. While the liquefied gas from the primary inlet flows through the heat exchanger to the primary outlet, it cools the entire mass of the heat exchanger approximately at the temperature of the liquefied Gas off. When using liquid nitrogen meaning this is a cooling to about minus 196 ° C. To Actuate the means for shutting off the primary inlet no liquefied cold gas flows more into the Heat exchanger. Now outside air can through the Heat exchangers are routed to the refrigerator, wherein the outside air in the heat exchanger is very strong cools. Any residues present in the heat exchanger evaporate on liquefied cold gas and escape at the same time in the fridge. The refrigerator can be so in proportion short time, for example less than 90 seconds, with ambient air be flooded and remains relatively cold.

Prefers the heat exchanger has a heat capacity on, which is a cooling of an ambient air volume, the about the volume of the refrigerator corresponds to at least 5 Kelvin, preferably more than 10 Kelvin. Depending on the temperature requirements in the cold room And the continuity of cooling can also be a significant one stronger cooling with correspondingly higher Heat capacity of the heat exchanger can be achieved.

Around As fast as possible a walkability of the cold room To be able to produce, it is advantageous if the heat exchanger between secondary inlet and secondary outlet one Ambient air umströmbare heat exchanger surface and has a construction which, when flowing through ambient air Delivering 50% of its stored cold in less than 120 seconds, preferably in less than 60 seconds, especially preferably in less than 30 seconds.

When It has been shown to be favorable when the heat exchanger at least one of the primary inlet with the primary outlet connecting pipe bends, preferably made of a copper alloy, contains. Copper has a suitable heat capacity and thermal conductivity and is used as material for Heat exchangers particularly suitable for cooling units.

Optionally, the heat capacity, that is, the cold storage capacity, in the heat exchanger by an additional Latentwärmespei be increased cher, which is preferably integrated in the heat exchanger. Latent heat storage contain a material which has a phase transition in the desired temperature range and can absorb and release a lot of heat or cold in this area. In the present case, a latent heat storage can be used with a phase transition in the vicinity of the desired temperature of the cold room.

While the ventilation of the cold room with supply of Ambient air through the heat exchanger can vary depending on the duration the ventilation cause ice formation in the heat exchanger, because there the moisture contained in the ambient air largely freezes. Although this has the advantage that the moisture is not in the refrigerator and forms ice there, but in the long term frequent short vents and subsequent immediate cooling of the heat exchanger to a lead to complete icing. For this reason has the fiction, contemporary device in one special design bypass means for feeding from liquid cold gas into the refrigerator below Bypassing of the heat exchanger. So may after the end the commissioning directly reliquefied gas into the refrigerator be sprayed without the heat exchanger directly to cool again. This has enough time defrosting before the described procedure starts over, by passing the liquefied gas back through the heat exchanger the cooling space is supplied. The bypass device can be in a simple bypass line between primary inlet and primary outlet of the heat exchanger exist. Of course, a completely separate line from the Reservoir with liquefied gas to the refrigerator be used. Depending on the design, the same can be done Inlets or other inlets be used when operating in the first time interval.

While the primary system of the heat exchanger for the flow of liquefied gas is formed, ie may have a relatively small line cross section, the Secondary system for the passage of relatively large Quantities of ambient air should be designed to make it as an air cooler can serve. The secondary inlet of the heat exchanger is preferably via a connecting line with a Blower connected to the environment. To prepare the Inspection of the refrigerator promotes the fan in a short time a large volume of ambient air in the Refrigerator.

A alternative embodiment of the invention includes that the secondary inlet no ambient air, but air the inside of the hold sucks. In this case, the air circulation serves the support of a convection, which the construction too naturally ventilated, especially at open Door. With this type of ventilation also occurs Heat in the hold, which is stored by the Cold of the heat exchanger cooled again becomes.

to Control or regulation of the processes described has the device according to the invention preferably a central control on, which has signal lines with Valves and / or the fan and / or sensors in the refrigerator or heat exchanger is connected. The central control typically receives information about the temperature and / or the oxygen content in the refrigerator or above the temperature in the heat exchanger. She then controls both normal operation during the first period takes place, as well as on request the ventilation in the second time interval, as well as the re-cooling first bypassing the heat exchanger in the third time interval.

The In particular, the invention also relates to a refrigerated vehicle a refrigerator for transporting goods and with a device as described above.

The Invention is for the ventilation of all types of Cold rooms with direct cooling through cryogenic liquid gas suitable. In a vehicle arise however, special benefits, if here are many cycles of entering the refrigerator are required, for. B. in delivery. The refrigerator can be permanently installed in the vehicle be, or z. B. transported as a refrigerated container.

One Embodiment of the invention, to which, however is not limited, and the characteristics and advantages of Inventive process will be described with reference to explained below by way of example.

1 shows a schematic diagram of the structure of a device according to the invention for cooling.

2 shows a corresponding refrigerated vehicle.

1 shows a device according to the invention in a schematic representation. A refrigerator 1 has a spraying device 10 on, through which to cool the refrigerator 1 a liquefied gas LIN, preferably liquid nitrogen, can be sprayed. In addition, the refrigerator has 1 an air inlet 11 on, by the ambient air AIR can be supplied to the ventilation before committing by a person. In normal operation is from a reservoir 17 liquefied gas LIN to the refrigerator 1 fed. With a fridge sensor 19 the temperature is measured and sent via a signal line 25 a central control 20 fed. The liquefied gas LIN passes through a supply line 12 and an inlet valve 7 in the primary inlet 3 a heat exchanger 2 and flows through a pipe coil in this 15 up to a primary outlet 4 , From there, the liquefied gas reaches the sprayer 10 , A bypass line 13 with a bypass valve 8th serves as a bypass of the heat exchanger 2 and allows the direct supply of liquefied gas to the refrigerator 1 bypassing the heat exchanger 2 ,

In a first period corresponding to the normal operation, the bypass valve becomes 8th from the central control 20 kept constantly closed while the inlet valve 7 from the central control 20 each is opened when the temperature in the refrigerator 1 exceeds a predetermined setpoint. In normal operation, therefore, liquefied gas flows again and again through the pipe hammers 15 and thus keeps the heat exchanger 2 at a very low temperature, using liquid nitrogen at a temperature of about -196 ° C.

If a commission of the refrigerator 1 by a person is imminent, must send a corresponding request signal to the central control 20 are given. This then holds the bypass valve 8th closed further and also closes the inlet valve 7 so that no more liquefied gas is left on the heat exchanger 2 is supplied. Then a fan 9 via a signal line 23 turned on, which ambient air AIR through a supply channel 14 to the secondary inlet 5 of the heat exchanger 2 passes. The ambient air AIR flows through the heat exchanger 2 and cools down strongly until it reaches the secondary outlet 6 arrives. From there it will continue to the air intake 11 in the fridge 1 , This situation is controlled by the central control 20 during a second period of time necessary for safe ventilation of the refrigerator 1 sufficient, maintained. After that is the fridge 1 through a door 26 freely accessible, but is at a much lower temperature than the outside temperature.

After the end of the inspection of the cold room 1 , despite the measures described to a temperature increase in the refrigerator 1 has led the central control 20 if not already done, the blower 9 and opens the bypass valve 8th , As a result, flows from the reservoir 17 through the supply line 12 and the bypass 13 again liquefied gas to the sprayer 10 and cool the fridge 1 quickly down to the setpoint temperature. This is done during a third period of time, which must be long enough to allow the heat exchanger 2 to allow a defrost. During the third period, the central control regulates 20 the temperature in the refrigerator 1 by opening and closing the bypass valve accordingly 8th with closed inlet valve 7 , After the end of the third period, the central controller switches 20 back to normal operation as described for the first period. Of course, the refrigerator needs 1 at least one exhaust outlet 27 have, which at low pressure in the refrigerator 1 opens to discharge the re-evaporated sprayed liquefied gas LIN or excess blown ambient air AIR to the outside.

To the effect of the heat exchanger 2 can strengthen as heat storage, in these a latent heat storage 16 be integrated. This should be its phase transition in the range of the target temperature of the cold room 1 so that he ventilates the cold room 1 the supplied ambient air AIR at least for a while to the desired temperature in the refrigerator 1 can cool down.

In 2 is a corresponding refrigerated vehicle 28 with a fridge 1 and a heat exchanger 2 shown schematically. Typically, there is a reservoir 17 for liquid nitrogen in the lower part of the refrigerated vehicle 28 and it has a door at the back 26 on.

The Use of the system according to the invention, in particular including a heat exchanger serving as a cold storage, allows a particularly economical operation of cold rooms that are relatively common to Loading or unloading must be entered. This occurs in particular in refrigerated vehicles in delivery traffic, where by the invention high savings of liquefied gas, mostly liquid Nitrogen, can be achieved.

1

refrigerator

2

heat exchangers

3

primary inlet

4

primary outlet

5

secondary inlet

6

secondary outlet

7

intake valve

8th

bypass valve

9

fan

10

spraying

11

air intake

12

supply

13

bypass line

14

feed

15

coil

16

Latent heat storage

17

reservoir for liquefied gas

18

temperature sensor

19

Refrigerator sensor

20

central control

21-25

signal lines

26

Fridge door

27

exhaust outlet

28

Reefer Truck

LIN

liquefied Gas, in particular liquid nitrogen

AIR

ambient air

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - EP 1252471 B1 [0004]

Claims (15)

Method for cooling at least one cold room ( 1 using liquefied cold gas (LIN) using a heat exchanger ( 2 ), which can be cooled by the liquefied gas (LIN) and above the refrigerator ( 1 ) Outside air (AIR) can be supplied, characterized in that at least a part of the cooling in a first period of time by supplying liquefied gas (LIN) via the heat exchanger ( 2 ) to the cold room ( 1 ) and that for venting the supply of liquefied gas (LIN) is interrupted and in a second period the supply of outside air (AIR) via the heat exchanger ( 2 ) he follows. A method according to claim 1, characterized in that in a third period of time liquefied gas (LIN) the refrigerator ( 1 ) bypassing the heat exchanger ( 2 ) is supplied. A method according to claim 2, characterized in that the third period of time is chosen as long as the heat exchanger ( 2 ) needed for defrosting. A method according to claim 1 or 2, characterized in that as a heat exchanger ( 2 ) a heat storage with suitable heat capacity and surface, in particular with a coil ( 15 ), preferably made of copper, is used, which is successively flowed through by the liquefied gas (LIN) in the first time period and flows around by the outside air (AIR) in the second time period. Method according to one of the preceding claims, characterized in that as the liquid cold gas nitrogen is used. Device for cooling at least one cold room ( 1 ) by means of a liquefied gas (LIN) with a heat-storing heat exchanger ( 2 ) containing at least one primary inlet ( 3 ) and at least one primary outlet ( 4 ) for liquefied cold gas (LIN) and at least one secondary inlet (LIN) 5 ) and a secondary outlet ( 6 ) for ambient air (AIR), the primary inlet with a Vorartsbehälter ( 17 ) for liquefied gas (LIN), the secondary inlet (LIN) 5 ) is directly or indirectly connectable to the environment and the primary outlet ( 4 ) and the secondary outlet ( 6 ) with the cold room ( 1 ) and where means ( 7 ) for shutting off the primary inlet ( 3 ) available. Apparatus according to claim 6, characterized in that the heat exchanger ( 2 ) has a heat capacity which is a cooling of an ambient air volume, which is approximately the volume of the cooling space ( 1 ) allows for at least 5 Kelvin, preferably more than 10 Kelvin. Apparatus according to claim 6 or 7, characterized in that the heat exchanger ( 2 ) between secondary inlet ( 5 ) and secondary outlet ( 6 ) has a heat exchanger surface and structure that can be flown around by ambient air (AIR) which, when ambient air (AIR) flows, releases 50% of its stored cold in less than 120 s, preferably less than 60 s, particularly preferably less than 30 s, allows. Device according to one of claims 6 to 8, characterized in that the heat exchanger at least one of the primary inlet ( 1 ) with the primary outlet ( 6 ) connecting pipe coil ( 15 ), preferably of a copper alloy. Device according to one of claims 6 to 10, characterized in that the heat exchanger ( 2 ) a latent heat storage ( 16 ) contains. Device according to one of claims 6 to 10, characterized in that bypass means ( 8th . 13 ) for supplying liquid cold gas (LIN) into the cold room ( 1 ) bypassing the heat exchanger ( 2 ) available. Device according to one of claims 6 to 11, characterized in that a connecting line ( 14 ) with a blower ( 9 ) as a link between the secondary inlet ( 5 ) of the heat exchanger ( 2 ) and the environment is present. Device according to one of claims 6 to 11, characterized in that the secondary inlet ( 5 ) of the heat exchanger ( 2 ) with the cold room ( 1 ), so that in particular when the door ( 26 ) in the cold room ( 1 recirculated ambient air (AIR) and through the heat exchanger ( 2 ) can be cooled. Device according to one of claims 6 to 13, characterized in that a central control ( 20 ) present with valves ( 7 . 8th ) and / or a blower ( 9 ) and / or sensors ( 18 . 19 ) in the cold room ( 1 ) and / or heat exchangers ( 2 ) via signal lines ( 21 . 22 . 23 . 24 . 25 ) and which these elements ( 7 . 8th . 9 ) according to a method of any one of claims 1 to 4 controls. Refrigerated vehicle with a cold room ( 1 ) for the transport of goods and with a device according to one of claims 6 to 14.