DE102019200673A1 - Refrigerator with automatically defrostable evaporator - Google Patents

Abstract

A refrigeration device, in particular a household refrigeration device, with at least a first storage compartment (20, 21) and a refrigerant circuit, in which a condenser (4), a throttle arrangement and a first one are located between a pressure connection (2) and a suction connection (9) of a compressor (1) Refrigerant line (25) of a first evaporator (7) cooling the first storage compartment (21) are connected in series, with a shunt line (11) parallel to the condenser (4) and a valve arrangement for selectively loading the condenser or the shunt line, characterized in that in the refrigerant circuit between the throttle arrangement and the first refrigerant line (25) of the first evaporator (7), a second evaporator (6) is connected and that the bypass line (11) is referred to as the second refrigerant line (15) over at least part of its length, is in closer thermal contact with the first evaporator (7) than with the second evaporator (6).

Description

The present invention relates to a refrigerator, in particular a household refrigerator with an automatically defrostable evaporator.

Commercial refrigeration devices with several storage compartments kept at different operating temperatures, in particular those with “static” evaporators, whose heat exchange with the storage compartment to be cooled is not intensified by a fan, typically with evaporators of the ToS or Rollbond type in the refrigerator compartment, thaw the evaporator passive heating, ie by waiting until the heat required for defrosting has flowed in from the surroundings. This can take a long time, especially at low ambient temperatures. If the compressor remains switched off during this time, even a colder storage compartment such as a cold storage compartment or a freezer compartment cannot be supplied with fresh refrigerant, and such a compartment can become undesirably heated.

One way to prevent such heating is to pre-cool the colder compartment below its normal operating temperature before the compressor is switched off to defrost. Such a strong cooling is only possible with reduced efficiency compared to normal operation; In addition, the ambient temperature range in which this approach is applicable is because the waiting time until the refrigerator compartment evaporator completely defrosts diverges as the ambient temperature approaches the operating temperature of the refrigerator compartment.

In order to prevent the waiting time from diverging at low ambient temperatures, it is therefore necessary to add heat to the evaporator to be defrosted in addition to the natural heat flow. DE 198 22 275 A1 discloses a refrigerator in which an electric heater is provided for this purpose. However, this undesirably increases energy consumption.

Out CN 106 225 358 A. and DE 10 2007 062 881 A1 refrigeration devices are known in each case, which make it possible to charge the evaporator with refrigerant, bypassing a condenser, and to heat it in this way. However, both concepts cannot be transferred to combination refrigeration units with several compartments, which are kept at different operating temperatures, since the heat input from the refrigerant during defrosting cannot be limited to one of the two evaporators.

The object of the present invention is to provide a refrigeration device with at least two evaporators connected in series, which reliably enables an energy-saving defrosting of the warmer evaporator even at a low ambient temperature.

The object is achieved in a refrigeration device, in particular a household refrigeration device, with at least a first storage compartment and a refrigerant circuit, in which a condenser, a throttle arrangement and a first refrigerant line of a first evaporator cooling the first storage compartment between a pressure connection and a suction connection of a compressor are connected to a shunt line parallel to the condenser and a valve arrangement for optionally acting on the condenser or the second refrigerant line, in the refrigerant circuit between the throttle arrangement and the first refrigerant line of the first evaporator a second evaporator is connected and that the second refrigerant line is in closer thermal contact with the first than with the second evaporator.

The close thermal contact can be established in that the second refrigerant line is an integral part of the first evaporator; However, it is also conceivable that the thermal contact only comes about when the refrigerator is assembled, e.g. the second refrigerant line is mounted in contact with the first evaporator.

The throttle arrangement can comprise a throttle point arranged downstream of the shunt line and the condenser, which is passed through both in the normal operation of refrigerant from the condenser on the way to the second evaporator and in the defrosting operation of refrigerant after passing through the second refrigerant line. However, it is not to be expected that a fixed flow resistance of a single throttle point is suitable for both refrigeration in normal operation and for defrosting; therefore such a throttle point should have a variable flow resistance and for this purpose e.g. be designed as an expansion valve. For reasons of cost, it is preferred that the throttle arrangement comprises a first throttle point connected between the condenser and the first refrigerant line and a second throttle point connected downstream of the second coolant line. These throttling points can then have a fixed flow resistance and in particular be designed as capillary tubes.

The first throttle point is preferably arranged as an internal heat exchanger in thermal contact with a suction line running from the first evaporator to the suction connection, in order to pre-charge refrigerant in normal operation in a manner known per se Pre-cool the evaporator below ambient temperature.

Such an arrangement as a heat exchanger is not expedient for the second throttle point, since when the second throttle point is reached the refrigerant is already sufficiently pre-cooled by the fact that it has given off heat to defrost the first evaporator. In order to minimize the inflow of heat from the first into the second storage compartment via the refrigerant line, the second throttling point can expediently be accommodated in a heat-insulating wall of the refrigeration device.

If, during defrosting, refrigerant enters the second evaporator via the second refrigerant line and the second throttle point, refrigerant must also flow from the second evaporator into the first refrigerant line of the first evaporator. In order to minimize the associated cooling effect on the first evaporator, the capacity of the shunt line and the second evaporator should be dimensioned in order to prevent liquid refrigerant from passing into the first evaporator during the loading of the second refrigerant line, i.e. the total amount of refrigerant circulating in the refrigerant circuit may at most exceed the capacity of the shunt line and the second evaporator so that that part of the refrigerant that is liquid during the defrosting can be accommodated in the shunt line and the second evaporator. In practice, the second refrigerant line should never be completely filled with liquid refrigerant during defrosting, since then the condensation in the second refrigerant line and thus the defrosting process comes to a standstill.

In order to ensure sufficient absorption capacity of the shunt line for liquid refrigerant, in particular if the first evaporator is a plate evaporator, the cross section of the second refrigerant line can be larger than that of the first, and / or a section of the shunt line downstream of the second refrigerant line can also be used as an expansion tank compared to other sections of the shunt line enlarged cross-section.

The total amount of refrigerant in the refrigerant circuit is preferably dimensioned such that it finds space in the liquid in the shunt line and the second evaporator; overflow of the second evaporator can be avoided regardless of the ambient temperature.

The second storage compartment cooled by the second evaporator should have a lower operating temperature than the first storage compartment. In particular, the first storage compartment can be a normal refrigeration compartment and the second a freezer compartment or a cold storage compartment.

In a simple embodiment, the valve arrangement can be formed by a shut-off valve arranged in the shunt line. The path through the condenser is then open in every state of the valve arrangement, but the proportion of the refrigerant which takes this path during the defrosting operation can be kept small by a suitable design of the refrigerant circuit. In particular, the flow resistance of the first throttle point should be large compared to that of the second throttle point. This not only causes a large part of the refrigerant to flow through the shunt line in defrost mode; it also ensures that the pressure (and thus the condensation temperature) in the second refrigerant line during defrosting remains lower than the pressure in the condenser during normal cooling. This prevents parts of the first evaporator from heating up well above 0 ° C during defrosting and subsequently having to be cooled down again, which is energy-intensive.

In order to completely prevent a flow of refrigerant to the second evaporator via the first throttle point and the associated cooling during defrosting, the valve arrangement can comprise a shut-off valve arranged parallel to the shunt line.

The first evaporator can be a plate evaporator, on the plate of which the second refrigerant line runs. Such a plate evaporator can be of conventional design; the second refrigerant line can only come into contact with such an evaporator in the course of assembling the refrigeration device.

Alternatively, the second refrigerant line can be an integral part of the same, which is already present in the refrigeration device before the evaporator is installed, e.g. by forming two separate channels for the first and the second refrigerant line in a single circuit board in a Rollbond evaporator, or in the case of a Rollbond evaporator two separate pipes, each with its own inlet and outlet connection, are attached to a common circuit board.

A finned evaporator can also be used as the first evaporator.

In known finned evaporators with electrical defrost heating, the latter often has the shape of an elongated heating wire or heating tube, the diameter of which is smaller than that of the first Refrigerant line is. If the diameter of the second refrigerant line is kept the same as that of the conventional electric defrost heater, the evaporator according to the invention can be implemented by simply replacing the electric defrost heater with the second refrigerant line without having to change anything on the fins or the first refrigerant line. This enables the invention to be implemented inexpensively.

The second refrigerant line can be fastened to the circuit boards of the evaporator by being pressed into notches on the circuit boards that are open at the edge.

• 1 eine schematische Darstellung des Kältemittelkreislaufs eines erfindungsgemäßen Kältegeräts;
• 2 einen schematischen Schnitt durch ein erfindungsgemäßes Kältegerät;
• 3 eine Draufsicht auf einen erfindungsgemäßen Plattenverdampfer;
• 4 einen Schnitt durch den Plattenverdampfer;
• 5 einen alternativen Schnitt durch den Plattenverdampfer;
• 6 einen erfindungsgemäßen Lamellenverdampfer; und
• 7 einen Schnitt durch den Lamellenverdampfer entlang einer zu den Lamellen parallelen Ebene.

Further features and advantages of the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying drawings. Show it:

• 1 a schematic representation of the refrigerant circuit of a refrigerator according to the invention;
• 2nd a schematic section through an inventive refrigerator;
• 3rd a plan view of a plate evaporator according to the invention;
• 4th a section through the plate evaporator;
• 5 an alternative section through the plate evaporator;
• 6 a lamella evaporator according to the invention; and
• 7 a section through the finned evaporator along a plane parallel to the fins.

The in 1 The refrigerant circuit shown comprises a compressor in a manner known per se 1 , from its pressure connection 2nd a pressure line 3rd a condenser 4th to a first choke point 5 extends. In one to the choke point 5 Subsequent low-pressure part of the refrigerant circuit is followed by an evaporator 6 and an evaporator 7 on top of each other, one from the evaporator 7 outgoing intake manifold 8th leads the refrigerant back to a suction port 9 of the compressor 1 .

In the pressure line 3rd is between the pressure connection 2nd and the condenser 4th a branch 10th intended. From the branch 10th a shunt line extends from 11 bypassing the condenser 4th and the throttling point 5 to a confluence 12th at the evaporator inlet 6 . The shunt line 11 is through a check valve 13 , typically a solenoid valve, can be shut off. A second check valve 14 can be between the branch 10th and the condenser 4th arranged to route the refrigerant to the condenser when needed 4th to block.

Part of the shunt line 11 is through a refrigerant line 15 formed in close thermal contact with the evaporator 7 runs. On the refrigerant line 15 a throttling point follows in the direction of flow of the refrigerant 16 . The flow resistance of the throttle point 16 can be chosen smaller than that of the throttle 5 to with the shut-off valve open 13 then sufficient refrigerant in the shunt line 11 to steer when no shut-off valve 14 is available. The throttling point is also located 5 in close thermal contact with the intake manifold 8th in order to form an internal heat exchanger in a manner known per se, in which the evaporator 7 extracted steam that through the throttle 5 to the evaporator 6 flowing refrigerant pre-cools, whereas such a thermal contact of the throttle point 16 is missing.

2nd shows an example of the arrangement of the components described above in a household refrigerator. The device has a body 17th with walls 18th , 19th , which are filled with a heat-insulating foam and at least two storage compartments 20 , 21 isolate from each other and the environment. The evaporators 6 , 7 are arranged to each one of the storage compartments 20 , 21 to cool. The case shown here is a plate evaporator of the Rollbond or ToS type, each on the inside of the walls 19th , typically between an inner container and the thermal insulation filling of the walls 19th are attached. Other types of evaporators are also possible, as will be explained in more detail later.

The thermal contact between the throttle point 5 and the suction pipe 8th is realized by the throttle point in a manner known per se 5 is designed as a capillary tube, which extends over at least part of its length within the suction tube 8th runs or around the intake manifold 8th is wrapped around. The capillary tube opens into an injection point 22 at the top of the evaporator 6 .

The branch 10th and the two check valves 13 , 14 are in the representation of the 2nd to a directional valve 23 drawn together. The shunt line 11 first reaches the evaporator 7 the warmer 21 of the two subjects 20 , 21 to the refrigerant line there 15 form, and descends from there to a second injection point 24th on the evaporator 6 of the colder subject 20 . The descending course of the shunt line 11 ensures that when the shunt line 11 is charged with refrigerant to the evaporator 7 defrost in the refrigerant line 15 condensing refrigerant to the evaporator 6 drains off and passes into it in liquid form. So during the Defrosting the evaporator 7 the supply of heat to the evaporator 6 and the volume flow through the latter, which is used to displace cold, liquid refrigerant from the evaporator 6 could be minimized.

The throttle point 16 between the refrigerant line 15 and the evaporator 6 ensures that during defrosting in the refrigerant line 15 the pressure is higher than in the evaporator 6 , and thus the temperature at which the refrigerant in the line 15 condensed, is higher than 0 ° C and the heat of condensation released for defrosting the evaporator 7 can contribute. The throttle point is preferably 16 set to a condensation temperature of a few degrees above 0 ° C, e.g. maximum + 5 ° C, in the refrigerant line 15 adjust. The closer the condensation temperature in the refrigerant line 15 at 0 ° C, the more selective the heat of condensation can only be in cold regions of the refrigerant line 15 are released, ie in those areas where there is still frost to be defrosted. In this way, the total amount of heat released during defrosting can be minimized.

Because the pressure difference between the refrigerant line 15 and the evaporator 6 during defrosting is smaller than that between the condenser 4th and the evaporator 6 in normal cooling operation, the flow resistance of the throttle point 16 be smaller than that of the throttle point 5 .

3rd shows a schematic plan view of the evaporator 7 and part of the evaporator 6 . On the evaporator 7 runs the refrigerant line 15 next to a refrigerant line 25th that have an end to an outlet of the evaporator 6 and with the other to the intake manifold 8th connected. It is sufficient if the refrigerant line 15 as shown by solid lines, only on part of the evaporator 7 , here within a single U-shaped loop of the refrigerant line 25th , extends; it can be the refrigerant pipe 25th but also, as shown with dashed lines, flank along their entire length. To one of the shunt line 11 to give sufficient volume to liquid refrigerant before the throttle 16 to be stowed without immediately causing the refrigerant line 11 is flooded, the cross section of the refrigerant line 15 larger than that of the line 25th to get voted. Alternatively or in addition, an expansion tank can be used 36 in the shunt line 11 between the refrigerant line 15 and the throttling point 16 be provided. Such an expansion tank 36 can expediently also provide space for a strainer which serves to trap particles carried in the refrigerant flow and to prevent the throttle point 16 to clog.

The evaporators 6 , 7 can be Rollbond or ToS evaporators.

4th shows a partial section through the evaporator designed as a roll bond evaporator 6 along the line IV-IV 3rd . During cooling operation, the volume flow in the refrigerant line 25th due to the resulting steam increases to the downstream end and this steam is sucked off, decreases in the refrigerant line 15 the volume flow due to condensation to the downstream end. In order for the condensed refrigerant to reach the downstream end reliably and without being hindered by steam bubbles, the cross section of the line can 15 be chosen larger than that of the line 25th . Both lines 15 , 25th are in the usual way by embossing grooves in a board 26 formed with a second, flat board 27 is soldered or connected in some other suitable way. The flat board 27 is on the inner container 28 attached snugly; the gutters of the other board 26 plunge into the heat-insulating foam of the wall 19th a.

5 shows a corresponding section through a ToS evaporator. The refrigerant line 25th is through solder 29 thermally conductive with a base plate 30th connected. The refrigerant line could also be used in a corresponding manner 15 as an integral part of the evaporator 6 on the base plate 30th be soldered. In the variant shown here, the solder is between the refrigerant line 15 and the base plate 30th through a thermal paste 31 replaced, and a large-area heat transfer contact between the base plate 30th and the refrigerant line 15 is ensured by placing the refrigerant line 15 a slide 32 taut over the foam-side surface of the base plate 30th is glued. This slide 32 gives the pressure of the expanding foam to the refrigerant line when foaming 15 further so that this is firm and good heat transfer to the base plate 30th is present.

Again related to 3rd is the confluence 12th here on the vaporizer 6 placed. This is especially easy when the vaporizer 6 is a rollbond vaporizer.

According to an alternative embodiment, the evaporator 7 , possibly also the evaporator 6 , replaced by a finned evaporator in one of the storage compartments to be cooled by it 21 , 20 remote evaporator chamber and is forced-ventilated by a fan. 6 shows such an evaporator. It comprises a large number of lamellae arranged parallel to one another 33 , in the elongated holes 34 are punched. Through these oblong holes 34 extend hairpin-shaped curved sections of the refrigerant line 25th . The refrigerant line 15 runs parallel to each such sections along two side surfaces of the evaporator 7 . To the refrigerant line 15 on the slats 33 The slats are able to be fixed 33 each as in 7 more clearly seen, with notches open to the edge 35 into which the refrigerant line 15 is pushed in and clamped.

The shunt line is in normal cooling operation 11 through the check valve 13 locked. Refrigerant is from the compressor 1 in the condenser 4th pumped in, condensed there and reached via the throttling point 5 the evaporator 6 . By placing a large part of the liquid refrigerant in the first evaporator 6 evaporates, its cooling capacity is higher than that of the evaporator 7 and the temperature of the storage compartment 20 accordingly lower than that of the storage compartment 21 .

The shunt line is in defrost mode 11 open, and depending on whether the check valve 14 Most of the refrigerant or all of the refrigerant enters the shunt line or not 11 . There it condenses predominantly at the coldest points, ie at those points on the refrigerant line 15 which are themselves covered with ice, or which if the refrigerant line 15 itself is already ice-free, remaining ice on the slats 33 and the refrigerant line 25th are neighboring.

The amount of refrigerant in the refrigerant circuit is selected so that the evaporator overflows 6 , ie penetration of liquid refrigerant from the evaporator 6 into the refrigerant line 25th of the evaporator 7 , can be safely prevented. For this purpose, the flow resistance of the throttle point 16 and the delivery rate of the compressor 1 be coordinated so that the amount of liquid refrigerant caused by the temperatures of the two evaporators 6 , 7 and the vapor pressures corresponding to these temperatures in the pressure difference specified therein the throttling point 16 happens is not greater than the amount that is in the evaporator at the same time 6 evaporates so the amount of liquid refrigerant in the evaporator 6 Do not grow during defrosting and to displace liquid refrigerant from the evaporator 6 into the refrigerant line 25th can lead. At the same time, the refrigerant line 11 do not fill up completely with liquid refrigerant during defrosting, since then there is no further condensation in the refrigerant line 11 is more possible and the defrosting process practically comes to a standstill. Under no circumstances should there be so much refrigerant that the evaporator 6 and the refrigerant line 11 can be filled with liquid refrigerant at the same time.

Reference list

1

compressor

2nd

Pressure connection

3rd

Pressure line

4th

Condenser

5

Throttling point

6

Evaporator

7

Evaporator

8th

Intake manifold

9

Suction connection

10th

branch

11

Shunt line

12th

confluence

13

Check valve

14

Check valve

15

Refrigerant line

16

Throttling point

17th

Body

18th

wall

19th

wall

20

Storage compartment

21

Storage compartment

22

Injection point

23

Directional control valve

24th

Injection point

25th

Refrigerant line

26

circuit board

27

circuit board

28

Inner container

29

Lot

30th

Base plate

31

Thermal paste

32

foil

33

Slat

34

Long hole

35

score

36

surge tank

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 19822275 A1 [0004]
• CN 106225358 A [0005]
• DE 102007062881 A1 [0005]

Claims (15)

Refrigeration device, in particular household refrigeration device, with at least a first storage compartment (20, 21) and a refrigerant circuit, in which a condenser (4), a throttle arrangement and a first refrigerant line between a pressure connection (2) and a suction connection (9) of a compressor (1) (25) a first evaporator (7) cooling the first storage compartment (21) are connected in series, with a shunt line (11) parallel to the condenser (4) and a valve arrangement for optionally acting on the condenser or the shunt line, characterized in that in a second evaporator (6) is connected to the refrigerant circuit between the throttle arrangement and the first refrigerant line (25) of the first evaporator (7) and that the shunt line (11) is referred to as the second refrigerant line (15) over at least part of its length closer thermal contact with the first evaporator (7) than with the second evaporator (6). Refrigerator after Claim 1 characterized in that the throttle arrangement comprises a first throttle point (5) connected between the condenser (4) and the first refrigerant line (25) and a second throttle point (16) connected downstream to the second coolant line (15). Refrigerator after Claim 2 , characterized in that the first throttle point (5) is arranged as an internal heat exchanger in thermal contact with a suction pipe (8) running from the first evaporator (7) to the suction connection (9). Refrigerator after Claim 2 or 3rd , characterized in that the second throttle point (16) is housed in a heat-insulating wall (18) of the refrigerator. Refrigerating appliance according to one of the preceding claims, characterized in that the capacity of the shunt line (11) and the second evaporator (6) is dimensioned in order to allow liquid refrigerant to pass from the second evaporator (6) into the second refrigerant line (15) to avoid the first evaporator (7). Refrigerating appliance according to one of the preceding claims, characterized in that a second storage compartment (20) cooled by the second evaporator (6) has a lower operating temperature than the first storage compartment (21). Refrigerating appliance according to one of the preceding claims, characterized in that the valve arrangement comprises a shut-off valve (13) arranged in the shunt line (11). Refrigerator after Claim 7 , characterized in that the valve arrangement comprises a shut-off valve (14) arranged parallel to the shunt line (11). Refrigerator according to one of the Claims 1 to 9 , characterized in that the first evaporator (7) is a plate evaporator and the second refrigerant line (15) runs on a plate (27, 30) of the first evaporator (7). Refrigerator according to one of the Claims 1 to 9 , characterized in that the first evaporator (7) is a Rollbond evaporator and the first and second refrigerant lines (25, 15) are formed by two separate grooves of a plate (26) of the Rollbond evaporator. Refrigerator according to one of the Claims 1 to 9 , characterized in that the evaporator is a ToS evaporator and the first and second refrigerant lines (25, 15) are formed by two pipes attached to the same plate (30) of the first evaporator. Refrigerator according to one of the Claims 9 to 11 , characterized in that the plate evaporator (6) has two input connections (22, 24). Refrigerator according to one of the Claims 1 to 8th , characterized in that the evaporator (7) is a finned evaporator. Refrigerator after Claim 13 , characterized in that the second refrigerant line (15) has a smaller diameter than the first refrigerant line (25). Refrigerator after Claim 13 , characterized in that the evaporator (7) has a plurality of fins (33) which are crossed by the first refrigerant line (25), and in that the second refrigerant line (15) is held in open-edge notches (34) in the fins (33) is.

Images