WO2010091951A2

WO2010091951A2 - Refrigeration unit having uniform temperature distribution

Info

Publication number: WO2010091951A2
Application number: PCT/EP2010/050899
Authority: WO
Inventors: Bernd Schlögel; Walter Woldenberg
Original assignee: BSH Bosch und Siemens Hausgeräte GmbH
Priority date: 2009-02-13
Filing date: 2010-01-27
Publication date: 2010-08-19
Also published as: DE102009000840A1; EP2396610A2; WO2010091951A3

Abstract

The invention relates to a refrigeration unit having a heat-insulated storage chamber (1) and a vaporizer (4) having at least two injection points (11, 12) that cools the storage chamber (1), wherein the two injection points (11, 12) are separated by a region (4-1, 4-2,..., 4- 4; 17-1) of the vaporizer that is cooled solely by coolant supplied to one of the injection points (11).

Description

Refrigeration device with uniform temperature distribution

The present invention relates to a refrigerator, in particular a household refrigerator. The evaporator of such a refrigerating appliance usually has a refrigerant pipe guided in numerous loops, into which liquid refrigerant is injected at one end, while at the other end evaporated refrigerant is sucked off. The cooling capacity is distributed unevenly on such an evaporator, on the one hand because the temperature of the refrigerant is lowest immediately after passing through the injection point and on the other hand because the maximum achievable at a given point of the refrigerant line cooling capacity is limited by the flow rate of liquid refrigerant, which, of course, becomes progressively smaller due to the evaporation progressing on the way from the point of injection to the suction connection. In order nevertheless to achieve a reasonably uniform temperature distribution in a storage chamber cooled by the evaporator, the injection point is usually arranged at an upper and the suction connection at a lower end of the evaporator, so that the available cooling capacity in the upper region of the evaporator is higher and cooled air there due to its relatively high density can flow from alone into a lower area of the storage chamber.

The higher the storage chamber, the more difficult it is to ensure a uniform temperature distribution in it. This problem arises in particular in large-size refrigerators, especially in freezers in which dense-packed refrigerated goods significantly affect the convection of the air in the storage chamber. Also, the evaporator itself can be a flow obstacle, especially if he, as in household freezers quite common, several arranged one above the other in the storage chamber plate-like segments.

To ensure that the entire contents of such a device are adequately cooled, the temperature at the warmest point in the storage chamber must be used as a reference for the control of the compressor operation. As a result, at locations of the storage chamber which are better cooled than the measuring point,

Temperatures are reached that are several degrees lower than required. To maintain these unnecessarily low temperatures requires considerable power. The energy efficiency of a refrigeration device is therefore generally the better, the lower the temperature differences in its storage chamber.

DE 10 2007 016 849 A1 discloses a refrigeration device with three storage zones held at different temperatures, in which one storage zone is assigned an evaporator with two injection points and two refrigerant lines extending side by side over the surface of the evaporator from these injection points. One of these lines is connected in series with an evaporator of the second storage zone, the other with an evaporator of the third storage zone. An effect on the temperature distribution in the first storage zone does not duplicate the injection point at the evaporator.

Refrigeration appliances are also known in which a homogeneous temperature distribution in a storage chamber is achieved by means of a fan, which ensures increased air circulation in the storage chamber. However, the fan affects the efficiency of such a refrigerator in several ways. On the one hand, the operation of the fan directly leads to increased energy consumption of the device, on the other hand, the fan gives its waste heat mostly to the storage chamber whose air it circulates, with the result that the waste heat ultimately has to be eliminated via the evaporator of the chamber and in turn the energy demand for cooling increases.

Object of the present invention is therefore to provide a refrigeration device that achieves a homogeneous temperature distribution even in a large-sized storage chamber with purely passive, no drive energy consuming means.

The object is achieved in which in a refrigerator with a thermally insulated

Storage chamber and the storage chamber cooling, at least two injection points having evaporator, the injection points are clearly spatially separated from each other, more specifically, that the two injection points are separated by a portion of the evaporator, which is cooled solely by supplied at one of the injection points refrigerant. The spatial separation of the injection points results in two locally coldest points spaced apart in the storage chamber, whereby the distance between a locally coldest point and a locally or globally warmest Point of the chamber and, accordingly, also reduces the temperature gradient occurring at this distance.

Preferably, the distance between the injection points is a multiple of the distance between adjacent line sections of the evaporator.

A uniform refrigerant line may extend from the at least two spaced-apart injection points to a common suction point of the evaporator.

According to a first embodiment, this refrigerant line comprises two line sections, each starting from one of the injection points, which meet at a T-piece. Preferably, a suction line is connected to this tee at the same time, which leads to a refrigerant compressor.

According to a second aspect, the refrigerant piping may include an upstream pipe section extending from a first one of the injection sites to the second injection site, and a downstream pipe section extending from the second injection site to a suction pipe. Here, the refrigerant flows from the first and the second injection point mix on the downstream line section. By the supply of fresh refrigerant at the second injection point of the refrigerant flow is cooled to a certain extent, in order to ensure a sufficient cooling capacity on the adjoining to the suction line section.

Preferably, the cooling capacity of both line sections is at least approximately equal. For this purpose, the line sections - in particular at a wire tube evaporator - be at least approximately the same length. In the case of a plate evaporator in which different line cross sections can be easily realized, the sizing of the line cross sections for at least approximately the same residence times of the refrigerant in the two line sections can be taken care of.

The evaporator may be divided into a plurality of segments, each of the two pipe sections cooling at least one of the segments alone. The segments are preferably formed as a wire tube evaporator, that is, they comprise an in-plane meandering piece of pipe and a plurality of wires, each of which is fastened to the pipe piece at a plurality of crossing points.

These segments are conveniently arranged in several horizontal planes one above the other in the storage chamber to divide them into several superposed compartments.

In the case of the above-mentioned first embodiment, the injection points are preferably arranged on an uppermost and a lowermost of the segments.

In the case of the second embodiment, preferably the first injection point is located at an uppermost segment, while the suction line extends from a lowermost of the segments.

In this embodiment, the second injection point is preferably arranged on a pipe piece connecting two segments.

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

1 is a perspective view of an inner container of a refrigerator with an evaporator mounted therein according to the invention.

FIG. 2 is a perspective view of a wire tube type evaporator according to a first embodiment of the invention; FIG.

Fig. 3 is a perspective view of the evaporator according to a second

design;

FIG. 4 shows a plate evaporator analogous to FIG. 2; FIG. and

Fig. 5 is a similar to Fig. 3 plate evaporator. Fig. 1 illustrates the problem of the invention with reference to the perspective view of an inner container 1 of a household freezer with evaporator mounted therein 2. The evaporator 2 is divided into a plurality of superposed, held in grooves 3 on the side walls of the inner container 1 plate-shaped wire tube evaporator As can easily be seen, the respective meandering in a horizontal plane, each parallel pieces 15 at a distance of a few cm having coils 5 of the wire tube evaporator 4 and the wires crossing them 6 a flow obstruction, which obstructs the convection of air in the inner container 1. When fill in the operation of the device, the spaces between the wires 6 with frost, there is virtually no exchange of air between the compartments of the inner container 1 more. If these subjects also record closed-bottom drawers 7, convection in the inner container 1 is completely excluded.

In order nevertheless to prevent the formation of an excessive temperature gradient in the inner container 1, the evaporator 2 of a first embodiment of the invention results in the structure shown in Fig. 2 in a perspective view obliquely from behind. From a leading to a compressor, not shown suction line 8 branch off two throttle tubes 9, 10, which, when the compressor is in operation, lead liquid refrigerant. They rise along a rear corner of the inner container 1, namely the throttle tube 9 of the highest point to an injection point 11 at 4-1 designated here evaporator segment, the throttle tube 10, however, to an injection point 12 of a pipe section, which is approximately halfway up the evaporator 2 segments 4-4, 4-5 connecting together. The suction line 8 is connected to the lowest-lying evaporator segment 4-7. Thus, while the segments 4-1 to 4-4 are cooled exclusively by refrigerant supplied via the throttle pipe 9, the segments 4-5 to 4-7 are cooled by a mixture of the refrigerant from the throttle pipe 9 with fresh refrigerant from the throttle pipe 10. Thus, the segment 4-5 reaches a lower temperature than the immediately above segment 4-4.

In place of a continuous temperature gradient from bottom to top, a temperature profile is thus obtained which drops from a locally high temperature at the bottom of the inner container 1 to a first local minimum at the level of the segment 4-5, in the vicinity of segment 4-4 again reaches a local maximum and has a second local minimum at segment 4-1. The spatial distance between maximum and minimum temperature is thus significantly reduced, and heat flow through the chilled goods can contribute to a much greater extent to a compensation of the temperature differences, as is possible with a continuous over the entire height of the inner container 1 temperature gradient.

If the flow rates of the throttle tubes 9 and 10 are set appropriately, thus, the difference between the highest and lowest temperature in the inner container 1 can be significantly reduced. If throttle tubes 9 and 10 are used of the same cross-section, the ratio of their throughputs over the length of the throttle tubes used can be adjusted. Since the area of the evaporator 2 below the injection point 12 is smaller than above and in the lower region usually still a balance of the cooling capacity of the refrigerant from the upper injection point 1 1 is available, the flow rate of the throttle tube 10 should be smaller than that of the throttle tube 9 be. In order to accommodate the tube length required for this purpose, 10 loops 13 are formed in the throttle tube.

In the embodiment shown in Fig. 3, the positions of suction and second injection point 12 are reversed. The suction line 8 starts from a piece of pipe between the segments 4-4 and 4-5, and in the suction line 8 countercurrently guided throttle pipes 9, 10 emerge from this in the vicinity of the located between the segments 4-4 and 4-5 suction port 14 up and down to pass into injection ports 1 1, 12 of the uppermost and lowermost segment 4-1, 4-7. In this embodiment, locally coldest points of the inner container 1 are respectively at the level of the segments 4-1, 4-7, while the warmest region is at the level of the segments 4-4, 4-5. While in the embodiment of FIG. 2, four zones of the inner container 1 each have local extremes of temperature, in this embodiment, there are only three, which is less favorable for a temperature compensation in the inner container 1 per se. A better effectiveness may still be achieved with the second embodiment, however, because a mixing of fresh and already heated refrigerant at the injection point 12 is omitted. Figs. 4 and 5 show the application of the principle of the invention to a

Plate evaporator. On a one-piece evaporator plate an injection point 1 1 are arranged at an upper corner and a suction port 14 at a lower corner in a conventional manner. In about the middle of a connecting the terminals 11, 14 edge of the evaporator plate, a second injection point 12 is formed, which opens into the same refrigerant line as the upper injection point 11. The refrigerant line extends across the board in meanders with mutually parallel line sections 15. Since at the In the middle injection point 12 entering refrigerant flows only over the lower half of the board exists in the upper part of the board between the injection points 1 1, 12 a cooled exclusively on the injection point 1 1 area 17-1, while a lower portion 17-2 of the board by Refrigerant from both injection points 11, 12 is cooled simultaneously. The two areas 17-1, 17-2 are substantially coextensive, and also the lengths of the line sections extending into the area 17-1, 17-2 are substantially the same. As long as only at one of the two injection points 1 1, 12 refrigerant is injected, consequently, the cooling capacity of the area 17-1, 17-2 is substantially equal.

In the evaporator circuit board shown in Fig. 5, injection ports 11, 12 are disposed at upper and lower corners of the board, and a refrigerant piping passes over board sections 17-1, 17-2 to a suction port located centrally between the injection ports. Since the areas 17-1, 17-2 cooled in each case exclusively via one of the injection points 11, 12 are essentially the same area and the line sections running on them are of equal length, the cooling capacity of the sections 17-1, 17-2 is the same here as well, when both injection points 1 1, 12 are acted upon simultaneously with refrigerant.

Claims

claims

1. Refrigeration appliance, in particular household refrigeration appliance, with a thermally insulated

Storage chamber (1) and a storage chamber (1) cooling, at least two injection points (11, 12) having evaporator (4), characterized in that the two injection points (11, 12) by a region (4-1, 4-2 , ..., 4-4, 17-1) of the evaporator are separated, which is cooled solely by at one of the injection points (11) supplied refrigerant.

2. Refrigerating appliance according to claim 1, characterized in that the distance between the injection points (1 1, 12) is a multiple of the distance between adjacent line sections (15) of the evaporator (4).

3. Refrigerating appliance according to one of the preceding claims, characterized in that a refrigerant line in the evaporator (4) from the at least two spaced-apart injection points (1 1, 12) extends to a common suction point (14).

4. Refrigerating appliance according to claim 3, characterized in that the refrigerant line comprises two line sections, each emanating from an injection point (11, 12) and meet at a T-piece (14) to each other.

5. Refrigerating appliance according to claim 4, characterized in that to the T-piece (14) has a suction line (8) is connected, which leads to a refrigerant compressor.

6. Refrigerating appliance according to claim 3, characterized in that the refrigerant line extending from a first of the injection points (1 1) to the second injection point (12) extending upstream line section and from the second injection point (12) to a suction pipe (8) downstream conduit section.

7. Refrigerating appliance according to claim 4, 5 or 6, characterized in that the two

Line sections have at least approximately the same cooling performance.

8. Refrigerating appliance according to one of claims 4 to 7, characterized in that the two line sections have at least approximately equal lengths.

9. Refrigerating appliance according to one of claims 4 to 8, characterized in that the evaporator (4) comprises a plurality of segments (4-1, ..., 4-7), wherein each of the two line sections of at least one of the segments (4 -1, ..., 4-4; 4-5, ..., 4-7) alone cools.

10. Refrigerating appliance according to claim 9, characterized in that each segment (4-1, ..., 4-7) comprises a meandering in a plane pipe section (5) and a plurality of wires (6), each of which at several Crossing points on the pipe section (5) is attached.

11. Refrigerating appliance according to claim 9 or 10, characterized in that the segments (4-1, ..., 4-7) are arranged one above the other in several horizontal planes in the storage compartment (1).

12. Refrigerating appliance according to claim 11, as far as dependent on claim 4, characterized in that the injection points (11, 12) on an uppermost (4-1) and a lowermost (4-7) of the segments are arranged.

13. Refrigerating appliance according to claim 11, as far as dependent on claim 4, characterized in that the first injection point (1 1) on a topmost segment

(4-1) is arranged and the suction line (8) from a bottom of the segments (4-7) emanates.

14. Refrigerating appliance according to claim 13, characterized in that the second injection point (12) is arranged on a two segments (4-4, 4-5) connecting pipe section.