KR20100032388A - Rear wall condenser for domestic refrigerators and freezers - Google Patents

Abstract

The invention relates to a condenser for refrigerators and freezers,with free convection, particularly for domestic refrigerators and freezers. The condenser has at least one tape-like pipeline (1), the width of which is at least twice the thickness, which has at least two separate channels (3, 4) which extend next to one another and which, when used as intended, extend on edge and largely close to and parallel to the lower edge of the refrigerator or freezer. For pipeline sections, disposed consecutively in the flow direction, the upper edge of a preceding section is offset in the flow direction parallel to the lower edge of the pipeline section which follows. A reasonably priced condenser with excellent heat exchange properties can be produced by the use of conventional, commercial, extruded aluminum profile pipes.

Description

Rear wall condenser for home refrigerators and freezers {REAR WALL CONDENSER FOR DOMESTIC REFRIGERATORS AND FREEZERS}

The present invention relates to a condenser for cooling machines using gravity type convection, in particular for home refrigerators, freezers or combined refrigerators / freezers, which can be manufactured easily and economically and are characterized by high efficiency. It is done.

Common refrigerators, freezers or combined refrigerators / freezers are so-called compressed refrigerators. Refrigerators operating according to other cooling principles, such as absorber refrigerators with low noise generation or thermoelectric refrigerators which enable compact designs, offer the particular beneficial features mentioned but consume significantly higher energy. It has a disadvantage and can therefore only be used for peripheral applications.

In compressed refrigerators, the compressor compresses the gaseous refrigerant so that the refrigerant is heated. The refrigerant passes through a condenser located outside the refrigerator. Condensers allow the refrigerant to release their heat into the environment to condense. The refrigerant then flows to an evaporator disposed inside the refrigerator via a throttle, such as an expansion valve or capillary tube, where the pressure of the refrigerant is lowered, where the refrigerant vaporizes and cools significantly. The evaporator provides heat exchange that allows the internal space of the refrigerator to cool.

The energy consumption of a compressed refrigerator is highly dependent on the rate at which the condenser can release heat to the environment. On the one hand, because energy and power prices are always on the rise and on the other hand, the environmental awareness of humans is growing, it is increasingly important to manufacture energy-saving home refrigerators.

Condensers used in household refrigerators generally include a tube that bends into a serpentine shape with wire ribs welded to the tube for better heat dissipation. In order to increase heat release by heat radiation, the tube and the wire ribs are provided with a black paint coating.

However, the condenser has the disadvantage that the wire ribs are heated to the same temperature as the tube only in the region where the wire ribs are coupled to the tube. Due to the relatively large distances between the tubes and the undesirable geometry of the wire ribs, ie large length and small diameter, the larger areas of the ribs are only slightly heated. As a result, the efficiency of the ribs is low. This leads to somewhat undesirable heat transfer, which in turn leads to an increase in the power consumption of the refrigerator.

Other known embodiments of condensers do not have wire ribs welded to the tube but have a metal plate that completely covers the tube. However, it would be necessary to provide as many welding points as possible between the tube and the metal plate to achieve efficient thermal interaction between the tube and the metal plate. More effectively, the tube can be joined with the metal plate by continuous welding or brazing seams. This concept is improved over the heat transfer surface but still provides a non-uniform temperature distribution. Therefore, the average temperature difference between the refrigerator and the air is lowered as the heat transfer rate per unit area is lowered. Another disadvantage is the relatively high manufacturing cost.

Many concepts are known from the state of the art aimed at improving heat dissipation and / or reducing the manufacturing cost of condensers for household refrigerators.

In EP 0 125 642 A2, for example, a rear wall condenser is proposed and the rear wall condenser consists only of tubes which are curved in a serpentine shape, where the straight tube sections have an elliptical cross section and the bent sections have a circular cross section. Since the tubes with elliptical cross section have a larger surface area compared to the tubes with circular cross section, the wires or metal plates are not welded to the tubes in this case. Although this leads to a reduction in the manufacturing cost, it will not improve the efficiency of the heat exchanger.

In EP 0 843 138 A1, a rear wall condenser for household refrigerators is described, the condenser comprising a tube which is bent in a serpentine shape and clamped between two metal plates. One of the two metal plates is joined to the third metal plate to form a receptacle filled with a high heat capacity liquid.

In CN 1616904 A, a back wall condenser is disclosed, wherein the back wall condenser consists of two tubes arranged one above the other horizontally, the two tubes arranged in a parallel and vertical arrangement. Are connected to each other by. Vertical tubes have a diameter of 1 to 3 mm, ie the vertical tubes are relatively thin. The refrigerator is distributed into vertical tubes by the upper horizontal tube and collected again in the lower tube. To improve heat dissipation, a metal plate can be mounted in the tubes. The use of multiple thin tubes or microchannel lines can increase the surface area and ensure effective heat exchange. However, the use of thin tubes or microchannel lines requires the tubes to be connected in parallel to minimize pressure loss, which leads to higher manufacturing costs. Another disadvantage arises from the fact that air continues to flow in the longitudinal direction of the tubes or microchannel lines, resulting in relatively thick layered boundary layers which hinder optimal heat release.

In addition, condensers for refrigerators using forced convection are known, wherein compression molded section lines of aluminum are used and the lines are tape-shaped and contain several parallel channels. Thus, EP 1 557 662 A2, US 2006/0144076 A1 and DE 10 2004 024 825 A1 describe condensers for forced convection with headers, while US 2005/0076506 A1 and JP 06317363 describe condensers for forced convection without headers. Describe them.

Due to the construction of these condensers these condensers are not suitable as side-wall condensers for refrigerators using gravity type convection. Although condensers are installed on the end and air can flow from bottom to top by gravity through the condensers, the condensers will have extremely poor efficiency because the first horizontal section lines produce high flow resistance and Secondly, due to the orientation of the lines, heat can hardly be released to the environment by radiation. However, condensers using gravity type convection dissipate heat up to 45% by radiation, unlike forced convection.

It is an object of the present invention to obviate the disadvantages of the state of the art previously described. In particular, it is an object to provide a condenser for household refrigerators using gravity type convection, which has high efficiency and can be easily manufactured at low cost.

This problem is solved by the features of claim 1 according to the invention; Useful embodiments of the invention are described in claims 2 to 15.

According to the invention, a condenser for refrigerators using gravity type convection comprises at least one line for a refrigerator formed like a tape, the width of the line being at least twice the line thickness size and the lines separated from each other. And integrate at least two channels extending adjacent to each other. In an application according to the intended use, the line is installed mostly parallel to the lower edge of the refrigerator on the end.

Air flows through the lines in a gravity type, ie from bottom to top, thus striking the narrow edges of the lines.

In line sections arranged successively in the flow direction, wherein the line sections are sections of one and the same line of the condenser or sections of other lines, the upper edge of the preceding line section is parallel in the flow direction with respect to the next line section. Is offset. In this way the air flow starts anew in each line section and thus the thickness of the insulating layered boundary layer in the line sections will be minimized. This can increase the efficiency of the condenser by 15%.

Parallel displacement of the upper and lower edges is achieved by arranging the line sections at a position offset parallel in the flow direction or by inclining the line sections. In terms of flow conditions, the effective tilt angles should be within the range of 0 ° to 45 °. It is also possible to offset and incline all of the line sections but this will not produce any particular advantage.

In an embodiment of the condenser according to the invention, in which the refrigerant is particularly affected by low flow resistance, the condenser comprises a header arranged perpendicularly to the inlet and outlet of the refrigerant. The two headers may have round, ie round, semicircle, oval and oval, or angled, ie triangular, square or rectangular flow cross sections. At the inlet, the header may incorporate a distributor.

The headers are connected mainly in parallel by a number of lines for the refrigerant arranged horizontally and parallel to each other at different vertical levels. However, the headers can also incorporate built-in elements that allow all lines or several parallel lines to be connected in series, so that the refrigerant flows through the condenser in a tortuous mode from top to bottom. The lines are installed in a straight line between the headers or bent in a wavy or serpentine shape in the horizontal direction.

It is intended that several lines be placed at a horizontal level next to each other and generally spaced in parallel. Preferably, the lines should be equipped with spacers, for example metal plates, which at the same time provide a secondary heat exchange surface.

In another embodiment of the condenser, in particular characterized by a simple configuration, the lines to the coolant are arranged in at least one layer which is curved in shape and formed as a spiral, spiral, spiral or three-dimensional serpentine contour. Headers are not used in this concept.

The preferred three-dimensional serpentine layout of the lines means that the side view is serpentine and also provides spiral depth. Typically, the line does not have circular or elliptical cross-sectional surfaces as generally found for screws / helicals, but is formed as a rectangle with rounded corners or contoured cross section (such as a “8-shaped” shape) (in a top view). ), But is characterized by spatially helixes or spirals.

A layer formed as a plane is understood to be a level arrangement of lines, such as, for example, a three dimensional winding, characterized by the depth of space. Depending on the nature of the invention, several layers of this type may also be arranged next to each other.

For common-type home refrigerators, it is sufficient in this embodiment to use only one line in the condenser which is preferably bent in a three-dimensional serpentine shape. The condenser is particularly easy to manufacture and ensures a sufficiently good heat exchange between the refrigerant and the ambient air. However, certain applications may also be set by some separate lines where spacers are installed, if applicable, or by lines arranged in several layers arranged one above the other.

It is also possible to use lines installed by connectors, for example sleeves. Lines of this configuration can be cost effective if lines of standardized lengths can be used.

On the one hand, in order to achieve large surface areas for heat transfer and on the other hand to avoid large pressure drops due to too small flow cross sections, line cross-sectional areas of 3 to 30 mm ² have no deformation and no headers with headers. Used for both modifications, where the hydraulic diameters of the channels range from 0.1 to 3 mm.

A particularly economical embodiment of the condenser is achieved if a compression molded section tube is used in the lines. The rib structure can be formed on the outside of the section tube for further improvement of the heat transfer properties.

In order to provide a simple connection to the household refrigerator, a line is formed with connectors at the inlet and outlet of the refrigerator, which outlet preferably incorporates a filter drier.

The lines are generally made of aluminum because aluminum has good thermal conductivity and can be reasonably and easily bent in cost. Coatings with high emission coefficients applied to the lines will result in improved heat release by radiation to ambient air.

According to the nature of the present invention, small condensers for refrigerators using forced convection are made of compression molded section tubes which are bent, so that several layers are formed in stacks arranged side by side in the flow direction, where they are placed side by side Line sections are offset relative to each other.

In condensers using forced convection, the offset arrangement can also lead to 10% higher efficiency. Other advantages arise from the fact that an arrangement of several layers can better use the available space compared to conventional single-layer configurations.

The invention will now be described in more detail with reference to two embodiments of condensers using gravity type convection.

1 schematically shows a cross section of a condenser line.

2 is a side view of a condenser with headers.

3 is a top view of the condenser with headers.

4 is a diagram of a condenser (no headers) with lines bent in a three-dimensional serpentine shape.

The line 1 according to FIG. 1 consists of aluminum tubes of a compression molded section having a width of 2.54 cm and a thickness of 2.1 mm. The sides 5 of the section tubes 1 are rounded, for example with a radius of 1 mm. In order to improve heat transfer properties, the sections are coated with black paint. The section tubes 1 are made of standardized material and thus can be provided at a reasonable price.

Line 1 has thirteen channels 3, 4 through which refrigerant 2 will pass. The channels 3 have a regular rectangular cross section with rounded corners and an edge length of approximately 1.5 mm. The two outer channels 4 are approximately rectangular in shape and the sides facing the outside are rounded. In this embodiment the channels 4 have a length of 1.5 mm and a width of 0.5 mm.

As is clear from FIG. 2, in the condenser with header tubes 9, the header tubes are connected by several pairs of lines 1 arranged one above the other in parallel and each of the pairs on a horizontal plane. Disposed and separated by spacers 8 (see FIG. 3). Pairs of lines 1 arranged on adjacent levels are offset relative to each other in the flow direction (not shown).

It is virtually impossible for pressure losses to affect efficiency in a condenser with headers, because each channel has 26 channels 3 extending in parallel, so a very large flow cross section is provided for the refrigerator. Because it becomes.

In the condenser without headers (see FIG. 4), the line 1 is bent into a three-dimensional serpentine shape, the bending radii being approximately 1.5 cm. The parallelly arranged lines 1 are spaced apart from each other by approximately 3 to 8 cm, which means that the lines are arranged relatively densely (see FIG. 4). Multiple parallel channels provide a large flow cross section for the refrigerators so that the pressure loss of the refrigerator is also minimized due to the large length of line 1.

Also in this embodiment, the line sections constituting the tortuous wires arranged one above the other are offset in the flow direction. The condenser can be manufactured particularly easily and economically since there is no need to weld any components.

In either embodiment, the planar tape-shaped lines 1 and the dense, parallel and curved arrangement of the lines ensure a condenser of a large surface area. The offset arrangement of the section tubes 1 causes the air flow to restart on the longitudinal sides of all sections. As a result, the thickness of the separated layered boundary layer at this location is minimized and efficient heat transfer is ensured.

The surface area of the condenser can be increased to the same tube length by using section tubes 1 having a rib structure.

The good thermal conductivity of the closely spaced channels 3, 4 and aluminum will cause the total surface area of the condensers to take the same temperature while operating within a very short time.

Condensers can be easily and economically manufactured because low cost standard components can be used due to the aluminum tubes of the compression molded section. Condensers can easily be cleaned, which contributes significantly to the constant performance characteristics of the condensers.

These two versions of condensers can achieve 15% higher heat dissipation than conventional condensers when the surface area is the same. On the other hand, the surface area of the condensers can be reduced by approximately 15% when at the same heat transfer rate.

List of Reference Numbers Used

1. Line / section tube

2. Refrigerant

3. Internal Channel

4. External Channel

5. Rounded side

6. Entrance

7. Exit

8. Spacer

9. Header

Claims (15)

A condenser for gravity type convection household refrigerators, comprising at least one line for refrigerant, The line is formed in the form of a tape, the width of the line being at least twice the thickness of the line, the line having two channels 3, 4 extending side by side, at least separated from each other, The line 1, when used according to its intended purpose, runs longitudinally, almost parallel, to the lower edge of the refrigerator on the end, in which case the upper edges are arranged identically or in succession in the direction of air flow. Respectively offset from the sections of the other lines to the lower edges of the subsequent section, Condenser. 2. The headers 9 according to claim 1, when used according to the intended purpose, the headers 9 at the inlets and outlets 6,7 connected with the lines 1 for the refrigerator installed vertically parallel to one another on the end. Including, the lines (1) is straight or bent horizontally in a wavy or serpentine shape, Condenser. The method according to claim 2, wherein the several lines 1 are horizontally spaced apart from each other, Condenser. The process according to claim 2 or 3, wherein each of the two lines 1 is arranged in a horizontal plane and spaced parallel to each other, Condenser. 5. The spacer 8 according to claim 2, wherein spacers 8 with large surface areas are arranged between the lines 1, the spacers functioning as secondary heat exchanger surfaces, 6. Condenser. The system of claim 1, wherein the line to the refrigerator is arranged in at least one layer formed as a plane of a spiral, helicoidal, helical or three-dimensional serpentine contour. Condenser. The line sections 1 according to any one of the preceding claims, wherein the line sections 1 are offset in the flow direction, Condenser. 8. The line section of claim 1, wherein the line sections are inclined by an angle of 0 ° to 45 °, Condenser. The line 1 according to any one of the preceding claims, wherein the line 1 has a cross-sectional area of 3 to 30 mm ² , Condenser. The channel according to claim 1, wherein the channels 3, 4 have hydraulic diameters of 0.1 to 3 mm. Condenser. The line (1) according to claim 1, wherein the line (1) is a compression molded section aluminum tube, Condenser. The line (1) according to claim 1, wherein the line (1) has a coating of black paint, for example characterized by a high emission coefficient for heat radiation. Condenser. The line (1) according to claim 1, wherein the line (1) has an increased outer surface area, for example through a rib structure. Condenser. 14. The line (1) according to any one of the preceding claims, wherein the line (1) has connections formed at the inlet and outlet (6,7) of the refrigerator, Condenser. The filter drier according to claim 1, wherein the filter drier is integrated in a connection piece of the refrigerator outlet. Condenser.

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