EP4265985A1 - Domestic refrigeration device with two evaporators - Google Patents

Abstract

A household refrigeration appliance (10) with a first storage area (15) with a first target temperature and a second storage area (16) with a second target temperature that is lower than the first target temperature, has a refrigerant circuit which has a first evaporator (20, 20', 20") for cooling the first storage area and a second evaporator (30) for cooling the second storage area, wherein the second evaporator (30) corresponds to the first evaporator (20, 20', 20") in the refrigerant circuit is connected in series. The first evaporator (20, 20', 20") has a refrigerant-side surface for heat exchange with refrigerant circulating in the refrigerant circuit and an air-side surface for heat exchange with the first storage area (15). The ratio of the refrigerant-side surface to the air-side surface is for the first evaporator (20, 20', 20") in the range 0.12 to 0.25, the first evaporator (20, 20', 20") being a plate evaporator on a rear wall (19) of the first storage area (15). . The air-side surface of the first evaporator (20, 20', 20") is less than 60% of the area available on the rear wall (19) of the first storage area (15). A pipe cross section of the refrigerant pipe is less than 18 mm².

Description

The present invention relates to a household refrigeration appliance with a first storage area with a first target temperature and a second storage area with a second target temperature that is lower than the first target temperature, and with a refrigerant circuit that has a first evaporator for cooling the first storage area and comprises a second evaporator for cooling the second storage area, the second evaporator being connected in series after the first evaporator in the refrigerant circuit.

From the DE 10 2016 224 434 a refrigeration device with several temperature zones is known.

The object of the present invention is to create a household refrigeration device with two storage areas and evaporators assigned to the storage areas, the second evaporator being assigned to the compartment with a lower target temperature than the first compartment, and being connected in series to the first evaporator in a refrigerant circuit , in which the higher temperature storage area has improved temperature stratification and the evaporator requires little effort.

The task is solved by a household refrigeration device and according to claim 1.

The invention relates to a household refrigeration device with a first storage area with a first target temperature and a second storage area with a second target temperature that is lower than the first target temperature, a refrigerant circuit which has a first evaporator for cooling the first storage area and a second evaporator for cooling the second storage area, wherein the second evaporator is connected downstream of the first evaporator in the refrigerant circuit in the flow direction of the refrigerant. Each evaporator has a refrigerant-side surface for heat exchange with refrigerant circulating in the refrigerant circuit and an air-side surface for heat exchange with the storage area assigned to the evaporator. The ratio of the refrigerant-side surface to the air-side surface of the first evaporator is in the range 0.12 to 0.25. The first evaporator is a plate evaporator on a rear wall of the first storage area and has a refrigerant pipe with a pipe cross section smaller than 18 mm ² on. The first storage area has an upper partial storage area in which the household refrigerator is not equipped with bearing shells, the air-side surface of the first evaporator being less than 75% of the area available on the rear wall of the upper partial storage area.

Such a household refrigeration device is in particular a household refrigeration device in which normal household quantities of food are stored in different compartments at different temperatures and possibly undergo temperature treatment. With evaporators that operate at different temperatures, storage compartments can be maintained or operated at different temperatures.

While the above-mentioned prior art provides good cooling performance and good heat transfer in the warmer compartment in a refrigerator with two storage areas with serially arranged evaporators with little effort for the upstream evaporator, this invention is aimed at further improved temperature stratification by designing the heat transfer at different heights of the warmer compartment.

The refrigerant-side surface is the inner surface of the refrigerant pipe and can be determined from the inner diameter and length of the pipe on the evaporator plate if the pipe cross-section is round. The air-side surface is the surface of the evaporator plate.

The pipe cross-section smaller than 18 mm ² is the cross-sectional area enclosed by the pipe wall through which refrigerant flows. This cross-sectional area is smaller than the usual cross-sectional area of the refrigerant pipes of today's household refrigeration devices.

Due to the good heat transfer of the first evaporator, it is not necessary in the household refrigerator for the evaporator to take up the entire area of the rear wall of the first storage area, nor of the upper partial storage area. The air-side surface of the evaporator is less than 75%, preferably less than 65%, more preferably less than 55%, of the area available on the rear wall of the upper partial storage area.

The household refrigeration appliance can be equipped with bearing shells in a lower partial storage area of the first storage area. Such storage trays can be intended for storing vegetables or as a cold storage area. Such bearing shells belong to the first storage area in terms of storage temperature, but can have their own target temperatures that deviate from an average target temperature of the first storage area by a few °C.

Preferably, these optional bearing shells are not cooled by an evaporator, which is arranged in the rear wall directly behind the shells, but by the first evaporator via a suitable air duct.

According to one embodiment of the invention, a width of the first evaporator is less than 80% of a width of the first storage area. In the first storage area, usually a refrigerator compartment, a desired temperature distribution can be achieved with a sufficient height of the evaporator; by using the area reduction through an evaporator that is narrower than the rear wall.

By choosing a thinner refrigerant tube than usual, preferably with an outside diameter less than or equal to 5 mm, a longer refrigerant tube than usual is required in order to meet the ratio of refrigerant-side surface to air-side surface in the first evaporator. This increased pipe length is used to cool areas of the evaporator plate differently by covering the evaporator plate with pipe loops.

Preferably, a top side of the evaporator borders a ceiling of the first storage area. In this sense, the ceiling includes a possible curve in an edge between the back wall and the ceiling. In this way, the warmest region of the first storage area under natural convection can be intensively cooled.

The injection point is preferably arranged to the side of the evaporator with the advantage of a well-cooled top corner of the evaporator.

The plate evaporator preferably has an injection point near an upper edge. This means that the flow of the refrigerant is supported by gravity.

The injection area is preferably inclined in order to impart a clear direction via gravity to the refrigerant flow, which is very slow at this point.

In a further embodiment of the invention, the entire pipe run is designed to slope from the injection point of the upstream evaporator to the beginning of the downstream evaporator in order to avoid unintentional refrigerant accumulation in any pipe areas.

According to a preferred embodiment of the invention, a pipe guide of the first evaporator is implemented more densely in a zone in the flow direction shortly after the injection point than in the pipe sections underneath. With the longer pipe length per evaporator surface shortly after the injection point than in the lower areas of the evaporator, an almost homogeneous temperature distribution on the evaporator surface can be achieved with the further advantage of a uniform frost loading of the evaporator.

The pipe routing of the plate evaporator below the zone is advantageously implemented less densely.

Preferably, the pipe routing of the plate evaporator is implemented below the zone with constantly decreasing horizontal width of pipe meanders.

According to a further embodiment of the invention, the plate evaporator has a constant downward pipe inclination in the flow direction of the refrigerant. This means that the flow of the refrigerant is supported by gravity.

According to a preferred embodiment of the invention, the plate evaporator has a constant downward pipe inclination in the flow direction of the refrigerant. The pipe inclination is preferably greater than 2°.

The plate evaporator is preferably a roll-bond evaporator, a tube-on-sheet (TOS) evaporator, or a tube-on-foil (TOF) evaporator.

A bearing shell can be arranged below the first storage area, with a lower edge of the plate evaporator being arranged at least 50 mm above an upper edge of the bearing shell.

Preferably, the lower edge of the plate evaporator is arranged at most 200 mm above an upper edge of the bearing shell.

A preferred embodiment of the invention is a household refrigerator as a refrigerator-freezer combination with a cold storage area and a freezer storage area. The first evaporator in the refrigerant circuit in the direction of flow is assigned to the cold storage area and the second evaporator in series is assigned to the freezer storage area.

In this refrigerator, when the refrigerator compartment evaporator is operating, liquid refrigerant flows quickly through the upstream refrigerator compartment evaporator and the freezer compartment evaporator is well filled with liquid refrigerant. Since there is no throttle point between the refrigerator compartment evaporator and the freezer compartment evaporator, their evaporation pressures and evaporation temperatures are approximately the same.

A preferred embodiment of the refrigerator-freezer combination is a so-called bottom freezer with a cold storage area at the top and a freezer storage area below. Here, the connection between the evaporators can preferably be made with a constant gradient, so that no accumulation of refrigerant takes place between the evaporators. An evaporator tube layout can be chosen so that the end of the tube on the refrigerator compartment evaporator is placed on the opposite side to the connecting tube. The free laying of the pipe enables length compensation, which is helpful for assembly in production.

A first variant of such a refrigeration device contains the first and second evaporators in series without a refrigerant pipe opening in between. This embodiment describes a refrigeration device in which both evaporators are always operated at the same time and the same amount of refrigerant flows through it. This design avoids branches and requires fewer valves in the refrigerant circuit.

In this refrigeration device, only the warmer of the storage areas can be provided and controlled with a temperature sensor. The refrigeration device is then usually designed in such a way that the target temperature of the colder compartment is usually slightly below. The invention improves the filling of the downstream evaporator with liquid refrigerant in this refrigeration device, especially after a compressor has started up. Since both evaporators are operated at the same time and thus an energetically advantageous utilization of the entire heat exchanger surfaces is achieved, very efficient operation of the device is achieved.

A second variant of such a refrigeration device contains the first and second evaporators in series with an opening of a refrigerant pipe between them. This embodiment describes a refrigeration device in which both evaporators are always operated simultaneously in a first circuit and the same amount of refrigerant flows through them. In a second circuit, only the downstream evaporator is operated.

In this refrigeration device, both storage areas, each equipped with a temperature sensor, can be controlled independently of one another. Most of the time, both evaporators are operated in series, but occasionally the evaporator in the colder storage area can be operated alone in order to precisely maintain its target temperature. This means that further improved energy efficiency can be achieved, as the colder compartment is always operated at its target temperature.

When both evaporators are operated in series, fans in one or both storage areas or on one or both evaporators can be used to change the coordination of the storage areas with regard to their target temperatures to a small extent.

A further embodiment of the first variant of the refrigeration device has a fan on the evaporator of the upstream compartment, and a control that lowers its fan speed at low ambient temperatures and/or increases its fan speed at high ambient temperatures.

Another embodiment of the first variant of the refrigeration device has a fan on the evaporator of the downstream compartment and a controller that controls the fan speed. This expands a control range in which the target temperatures of both storage areas can be maintained simultaneously in serial operation of the evaporators.

The household refrigeration appliance can have a lower partial storage area with bearing shells in the first storage area. The lower storage area including the shells is cooled by the first evaporator in the upper partial storage area. The household refrigerator can advantageously be designed in such a way that a cold air flow is created on the rear wall in front of the evaporator, which flows along the rear wall to the storage shells.

Fig. 1

eine schematische Darstellung eines erfindungsgemäßen Haushaltskältegeräts;

Fig. 2

eine schematische Darstellung der Anordnung von Verdampfern eines erfindungsgemäßen Haushaltskältegeräts; und

Fig. 3

eine schematische Darstellung eines Plattenverdampfers eines erfindungsgemäßen Haushaltskältegeräts.

Further features and advantages of the invention result from the following description of exemplary embodiments with reference to the attached figures. Show it:

Fig. 1

a schematic representation of a household refrigeration device according to the invention;

Fig. 2

a schematic representation of the arrangement of evaporators of a household refrigerator according to the invention; and

Fig. 3

a schematic representation of a plate evaporator of a household refrigerator according to the invention.

In the various embodiments, functionally identical elements are designated with the same reference numbers, similar elements with primed reference numbers.

In Fig. 1 a household refrigeration appliance 10 is shown as a refrigerator and freezer combination, the heat-insulating housing 11 of which has two first and second storage areas 15, 16 which are thermally separated from one another by a heat-insulating partition 12 and are arranged vertically one above the other and can be closed with separate doors 13 and 14. The higher-lying first storage area 15, which can be closed with the door 13, is designed as a refrigerator compartment, which is equipped with tiers 17 arranged vertically one above the other and used to store refrigerated goods.

The other second storage area 16, which is arranged below the refrigerator compartment and is separated from it by the heat-insulating partition 12, is designed as a freezer compartment, which has frozen food containers 18 that can be pulled out like drawers to accommodate frozen goods.

Both the refrigerator compartment and the freezer compartment are equipped with evaporators to maintain their intended storage area temperature, of which the evaporator 20 of the first storage area 15 is indicated as a plate evaporator on a rear wall 19 of the first storage area 15. The evaporators are integrated into a refrigeration circuit, not shown, within which a compressor supplying the evaporators with liquid refrigerant is arranged.

The first storage area 15 has an upper partial storage area 28, in which the household refrigerator 10 is not equipped with bearing shells, and a lower partial storage area 29, in which bearing shells 21 are arranged. The bearing shells 21 are closed by a cover 22. The distance 23 from the cover 22 to the lower edge of the evaporator 20 is between 50 and 200 mm.

The width 24 of the evaporator 20 is less than 80% of the width 25 of the rear wall 19 of the first storage area 15.

The evaporator plate 27 of the first evaporator 20 faces the first storage area with its air-side surface in order to cool the air of the first storage area. The air-side surface of the evaporator plate 27 or the first evaporator 20 is less than 60% of the area of the rear wall 19 of the first storage area 15.

Fig. 2 shows an arrangement of first evaporators 20 ' and second evaporator 30 of the household refrigerator 10 Fig. 1 .

The first evaporator 20' is designed as a tube-on-sheet (TOS) evaporator with a refrigerant tube 31 on an evaporator plate 27'. The evaporator plate 20' is arranged on a rear wall 19' of the first storage area 15, the width 24' of the evaporator plate 27' being less than 80% of the width 25' of the rear wall 19'.

The evaporator 20' can be arranged behind a wall of an inner container with the refrigerant pipe on the side facing away from the inner container.

An injection point 34 is arranged laterally outside the upper right corner of the evaporator plate 27 '. The refrigerant pipe 31 protrudes beyond the evaporator plate at the upper right corner of the evaporator plate 27 '. The pipe routing on the evaporator plate is implemented more densely in a zone 33 shortly after an injection point 34 than in the subsequent pipe sections.

A constant downward inclination of the refrigerant pipe 31 is maintained in order to avoid accumulation of refrigerant due to gravity in this pipe section. The constantly falling pipe run design generally avoids the nesting of pipe meanders. This results in a relatively simple pipe route in terms of production.

In the case of the refrigerant pipe 31, the evaporator outlet 36 is connected by a connecting section 37 to the second evaporator 30, which runs with a constant inclination. The refrigerant pipe 31 can have a different diameter in the section on the evaporator plate 27 'than in the connecting section 37.

The evaporator 30 can be a finned evaporator or a coil evaporator.

A first capillary 38 runs in an insulating material to the injection point 34.

In Fig. 2 an optional second capillary 39 is shown, which opens into the refrigerant pipe 31 at the junction 32 and forms an injection point 40 in the refrigerant pipe 31 at the inlet of the second evaporator 30. The optional second capillary 39 enables a two-circuit refrigeration device with a so-called intermediate injection of refrigerant into the downstream evaporator.

Fig. 3 shows a further embodiment of the first evaporator 20" with several independent changes compared to the first evaporator 20' Fig. 2 .

The injection point 34' of the refrigerant pipe 31' is now no longer on the side, but above the evaporator plate 27".

Below zone 33' the pipe routing is now increasingly less dense. On the one hand, the horizontal width of other pipe meanders is constantly decreasing. On the other hand, the tube meanders are pulled apart in the vertical direction, so that their vertical distance becomes increasingly larger.

The first evaporator 20" has an evaporator plate 27" which tapers downwards.

REFERENCE SYMBOL LIST

10

Household refrigeration device

11

Housing

12

partition wall

13, 14

door

15

first storage area

16

second storage area

17

Cake stand

18

Frozen food container

19, 19'

Back wall

20, 20', 20"

first evaporator

21

bearing shell

22

cover

23

Distance

24, 24', 25

Width

27, 27'

evaporator plate

28

upper partial storage area

29

lower partial storage area

30

second evaporator

31, 31'

Refrigerant pipe

32

confluence

33, 33'

Zone

34, 34'

injection point

36

Evaporator outlet

37

connection section

38

first capillary

39

second capillary

40

injection point

Claims (15)

Household refrigeration device (10) with a first storage area (15) with a first target temperature and a second storage area (16) with a second target temperature that is lower than the first target temperature, a refrigerant circuit comprising a first evaporator (20, 20', 20") for cooling the first storage area and a second evaporator (30) for cooling the second storage area, wherein the second evaporator (30) corresponds to the first evaporator (20, 20' , 20") is connected in series in the refrigerant circuit, wherein the first evaporator (20, 20', 20') has a refrigerant-side surface for heat exchange with refrigerant circulating in the refrigerant circuit and an air-side surface for heat exchange with the first storage area (15), and wherein the ratio of refrigerant-side surface to air-side surface for the first evaporator (20, 20', 20") is in the range 0.12 to 0.25, the first evaporator (20, 20', 20") being a plate evaporator on a rear wall (19) of the first storage area (15) is and has a refrigerant pipe (31) with a pipe cross section, characterized in that the first storage area (15) has an upper partial storage area (28) in which the household refrigerator (10) is not equipped with bearing shells, wherein the air-side surface of the first evaporator (20, 20', 20") is less than 75% of the area available on the rear wall (19) of the upper partial storage area (28), and the pipe cross section of the refrigerant pipe is less than 18 mm ² . Household refrigeration appliance according to claim 1, characterized in that a width (24) of the first evaporator (20, 20', 20") is smaller than 80% of a width (25) of the first storage area (15). Household refrigeration appliance according to claim 1 or 2, characterized in that the refrigerant pipe (31) of the first evaporator (20, 20', 20") has an outer diameter less than or equal to 5 mm. Household refrigeration appliance according to claim 1, 2 or 3, characterized in that an upper side of the first evaporator (20, 20', 20") borders a ceiling of the first storage area (15). Household refrigeration appliance according to one of the preceding claims, characterized in that an injection point (34') of the first evaporator is arranged to the side of the first evaporator (20, 20', 20"). Household refrigeration appliance according to one of the preceding claims, characterized in that the first evaporator (20, 20', 20") has an injection point (34, 34') near an upper edge. Household refrigeration appliance according to one of the preceding claims, characterized in that a pipe guide of the first evaporator (20, 20', 20") is implemented more densely in a zone (33) shortly after the injection point (34, 34') than in the pipe sections underneath . Household refrigeration appliance according to claim 7, characterized in that the guidance of the refrigerant tube (31) of the first evaporator (20, 20', 20") is implemented below the zone (33) with constantly decreasing width of tube meanders. Household refrigeration appliance according to one of the preceding claims, characterized in that the first evaporator (20, 20', 20") has a constant downward pipe inclination in the flow direction of the refrigerant. Household refrigeration device according to claim 9, characterized in that the pipe inclination is greater than 2°. Household refrigeration appliance according to one of the preceding claims, characterized in that a bearing shell is arranged below the first storage area and a lower edge of the first evaporator (20, 20 ', 20") is arranged at least 50 mm above an upper edge of the bearing shell. Household refrigeration appliance according to claim 11, characterized in that the lower edge of the first evaporator (20, 20', 20") is arranged at most 200 mm above an upper edge of the bearing shell. Household refrigeration appliance according to one of the preceding claims, characterized in that the first storage area (15) or the second storage area (16) has a speed-adjustable fan. Household refrigeration appliance according to one of the preceding claims, characterized in that the second evaporator (30) is connected in series after the first evaporator (20, 20', 20") in the refrigerant circuit without a refrigerant pipe opening in between. Household refrigeration appliance according to one of claims 1 to 13, characterized in that the second evaporator (30) is connected in series after the first evaporator (20, 20', 20") in the refrigerant circuit with an opening (32) of a refrigerant pipe (31) in between .

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