JPS6183889A - Heat exchanger for freezing machine - Google Patents

Abstract

PURPOSE:To achieve high efficiency, to reduce occupying space, to facilitate the manufacture and to reduce the defrosting energy by disposing more fin strips of refrigerating pipe and heater pipe fins near to the upstream side of the flow of heat exchanging fluid, and by bending or twisting the fin strips parallelly with the flow of the fluid. CONSTITUTION:Since the direction of protrusion of refrigerating pipe fins 15 and heater pipe fins 16 protruding from the surface of a refrigerating pipe 12 and a heater pipe 14 are different from the winding direction of a heat exchanging pipe 11, there is no restriction to the fins due to the winding, and as a result, the surface area can freely be set, a narrower winding pitch can be selected, and the occupying space can be reduced. Moreover, since the heat exchanging pipe 11 is wound parallelly with the airflow passing through a cooling chamber 5 and more number of fin strips 17, 18 are disposed near to the upstream side of fluid flow, a high heat exchanging efficiency can be obtained, and because the cooling effect of the upstream side fin strips which are prone to be frosted is lower than the downstream side, the uniform frosting will result, contributing to the reduction of the defrosting energy. Further, as the width of the fin strips in the pipe axial direction is constant, the manufacture can be facilitated.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention provides a heat exchanger for refrigeration machinery that achieves high efficiency, a reduction in exclusive volume, improved manufacturability, and a reduction in defrosting energy. Regarding.

[Technical background of the invention and its problems]

As is well known, in forced circulation type refrigeration machines, such as fan cool type refrigerators and showcases, refrigeration V (
Alternatively, a cooling chamber containing a heat exchanger and a cooling chamber are provided separately. The spaces are connected in series via a communication path, and air is forced to circulate between both rooms, thereby cooling the inside of the refrigerator compartment to a predetermined temperature.

By the way, as an evaporation heat exchanger incorporated in such a refrigeration machine, a plate fin type heat exchanger has conventionally been used exclusively. However, recently, it has been proposed to construct a heat exchanger using a heat exchange tube body formed by integrally extruding aluminum refrigerant tubes and fins. The container is already built into some refrigerators. A heat exchanger constructed of this integrally molded heat exchange tube has the advantage of inherently higher heat transfer coefficient and lower pressure loss than a plate-fin type heat exchanger.

However, in conventional heat exchangers configured using integrally molded heat exchange tubes, each fin is provided so that the tips of the fins face each other. The dedicated volume is larger than that of the exchanger, and as a result, there is a problem in that the entire refrigeration machine becomes larger. Also, when operating a refrigeration machine, it is necessary to periodically or irregularly remove frost that has adhered to the surface of the heat exchanger.
Conventional heat exchangers have the problem of non-uniform frost formation, which not only shortens the defrost interval but also takes a long time to defrost, resulting in low defrosting efficiency. Ta.

[Purpose of the invention]

The present invention was made in view of the above circumstances, and its purpose is to use an integrally molded heat exchange tube body, and to achieve high efficiency, a reduction in the exclusive volume, and an improvement in manufacturability. An object of the present invention is to provide a heat exchanger for a refrigeration machine that can reduce defrosting energy and defrosting energy.

[Summary of the invention]

A heat exchanger for a refrigeration machine according to the present invention includes a refrigerant pipe, a heater pipe connected in parallel to the refrigerant pipe via a strip-shaped connection part, and into which an electric heater for defrosting is inserted. From the length from the root to the tip of the refrigerant pipe-side fins and the refrigerant pipe-side fins that protrude on a line connecting the center of the heater pipe and the center of the refrigerant pipe on the surface of the heater pipe and the surface of the refrigerant pipe, respectively. A heat exchange tube body having short heater tube side fins and formed by integral extrusion of aluminum is placed on a surface perpendicular to a line connecting the center of the refrigerant tube and the center of the heater tube, and The refrigerant tube side fins and the heater tube side fins are arranged meanderingly on a plane parallel to the flow direction of the heat exchange fluid that exchanges heat with the refrigerant flowing through the refrigerant tube, and the refrigerant tube side fins and the heater tube side fins are respectively arranged along the tube axis. direction, the width in the tube axis direction is separated into a plurality of strip-shaped fin pieces, and the strip-shaped fin pieces are separated from each other into a plurality of strip-shaped fin pieces having a constant width in the direction of the tube axis, and each strip-shaped fin piece has a larger shape as it is located on the upstream side with respect to the flow direction of the heat exchange fluid. The fins are divided into a plurality of units having a large number of fins, and the tips of the units adjacent to each other in the tube axis direction are bent or twisted so that the tips thereof are separated from each other and the base portions are approximately parallel to the flow direction of the heat exchange fluid. It has become something that has been established.

〔Effect of the invention〕

With the above configuration, the protruding direction of the refrigerant pipe side fins and the heater pipe side fins protruding from the surface of the refrigerant pipe and the surface of the heater pipe is different from the direction in which the heat exchange pipe meanders. Therefore, the height of each fin does not affect the meandering, and the meandering does not limit the height of the fins. Therefore, the surface area of each fin can be set freely, and the meandering pitch can be narrowed to the maximum working limit of the heat exchange tube. Therefore, the exclusive volume can be significantly reduced compared to the conventional one. In addition, since the heat exchange tube having the above configuration is used,
Sufficiently high heat exchange efficiency can be obtained. In addition, the units constituted by the strip-shaped fin pieces are arranged approximately parallel to the flow direction of the heat exchange fluid and intermittently in the flow direction, and furthermore, are arranged on the upstream side with respect to the flow direction of the heat exchange fluid. The closer it is located, the wider it is. The heat transfer coefficient of each fin piece arranged in this way is the value near the leading edge of the flat plate boundary layer, so the cooling effect of each strip-shaped fin piece located on the upstream side where frost formation is most likely to occur is is lower than those located downstream. Therefore, frost can be formed almost uniformly from the upstream side to the downstream side. therefore,
It is possible to lengthen the time until clogging occurs, and as a result, the defrosting interval can be lengthened, resulting in energy savings. In addition, compared to the length from the root to the tip of the refrigerant pipe side fins, the heater pipe side fins are made shorter by the amount of the heater pipe, so that the heat transfer area of the fins etc. provided on both sides of the refrigerant pipes is reduced. can be made equal, and the cooling effects of both can be made equal.

Therefore, the surfaces of the refrigerant tube-side fins and the surfaces of the heater tube-side fins can be frosted to a substantially uniform thickness, making it possible to further lengthen the interval between snow removal operations. Moreover, since the heater tube is provided along the refrigerant tube in a thermally close state to the refrigerant tube, the heat generated by the defrosting heater can be quickly transferred to the refrigerant tube. therefore,
Furthermore, the defrosting energy can be further reduced. Furthermore, since the width of each strip-shaped fin piece in the tube axis direction is constant, the cutting operation for separating each strip-shaped fin piece can be completely mechanized, and manufacturing can be facilitated.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 schematically shows a fan-cooled refrigerator constructed by incorporating a heat exchanger according to the present invention.

That is, in the figure, 1 indicates a refrigerating room in which foods and the like are stored. The refrigerator compartment 1 is provided with a door 112 that can be opened and closed, and two opposing side walls are provided with an inlet 3 for introducing cold air and an outlet 4 for discharging cold air. The inlet port 3 and the outlet port 4 are
It communicates with the cooling chamber 5 via a communication path. The cooling chamber 5 accommodates a heat exchanger 6 according to the present invention and a fan 7 that forcibly circulates the air in the refrigerator compartment 1 along a path from the refrigerator compartment 1 to cooling 5 to the refrigerator compartment 1.

As shown in FIG. 2, the heat exchanger 6 is mainly composed of heat exchange tubes 11 arranged in a meandering manner. The heat exchange tube body 11 is formed by integral extrusion molding of aluminum, and as shown in FIG.
A heater pipe 14 and a refrigerant pipe 12 are connected in parallel via
and the length from the root to the tip of the refrigerant tube side fins 15 and the refrigerant tube side fins 15 protruding on the line connecting the center of the heater tube 14 and the center of the refrigerant tube 12 on the surface of the heater tube 14 and the surface of the heater tube 14, respectively. The heater tube side fins 16 are shorter than the heater tube side fins 16. The refrigerant tube side fins 15 and the heater tube side fins 16 are provided with notches perpendicular to the tube axis at a constant pitch in the tube axis direction, and each fin 15 and 16 is formed into a plurality of strip-shaped fin pieces 17 by these notches.
．． It is separated into 18 parts. Each short conical fin piece 17.18
is divided into a plurality of units W in which the number of strip-shaped fin pieces is larger as the unit is located on the upstream side with respect to the flow direction of the heat exchange fluid, which will be described later. Each unit W is bent alternately in opposite directions from its base so that two rows of units extending in the tube axis direction are formed in the circumferential direction.

After the defrosting heater 19 is inserted into the heat exchange tube 11 configured in this way, the defrosting heater 19 is inserted into the refrigerant tube 1.
2 and the center of the heater tube 14, and in a direction perpendicular to the flow direction Y while being bent in a direction parallel to the flow direction Y of the air flowing through the cooling chamber 5. The heat exchanger 6 is configured by being arranged in a meandering manner extending from the front to the right.

Here, the manufacturing process of the heat exchanger 6 will be briefly explained.

First, by integrally extruding aluminum, the refrigerant pipe 12 and the strip-shaped connecting portion 1 are assembled as shown in FIG. 4(a).
3, a heater tube 14, a refrigerant tube side fin 15, and a heater tube side fin 16 are integrated into a heat exchange tube body 11. Next, as shown in FIG. 4B, constant cuts P are provided in the refrigerant tube side fins 15 and the heater tube side fins 16, which are perpendicular to the tube axis. Next, the strip-shaped fin pieces 17, 18 formed in plurality in the tube axis direction by the cut P are divided into a plurality of units W, taking into consideration the meandering form, and each unit W is divided into a plurality of units W as shown in FIG. Alternately bend each piece in opposite directions from the base. Thereafter, the heat exchanger 6 is formed by arranging the heat exchange tubes 11 in a meandering manner so that the above-mentioned conditions are satisfied.

In this embodiment, when the meandering arrangement is performed, the gap R between the bent portions Q formed by the meandering is set smaller than the diameter of the bent portion Q. Further, in order to reduce the pressure loss at the bending portion Q, the strip-shaped fin pieces 17 and 18 located at this portion are twisted so as to be parallel to the flow direction Y.

Therefore, both ends of the refrigerant pipe 12 and both ends of the heater pipe 140 in the heat exchanger 6 configured as described above and housed in the cooling chamber 5 are connected to the cooling chamber 5, respectively.
It is led to the outside by passing through the side wall of the and,
One end of the refrigerant pipe 12 is connected to a compressor 21, as shown in FIG.
It is connected to the other end of the refrigerant pipe 12 via a condenser 22 and an expansion valve 23 in series. Further, both ends of the defrosting electric heater 19 led outside the cooling chamber 5 are connected to a power source 25 via a switch 24 . and the switch 24,
The compression 1121 and the fan 7 are driven and controlled by a control device (not shown). The control device detects the temperature inside the refrigerator compartment 1 using a temperature sensor installed in the refrigerator compartment 1, and controls the compressor 2 so that this temperature is always within a set range.
1 is 0N16FF III III. The control device detects the thickness of frost adhering to the upstream surface of the heat exchanger 6 using a frost sensor installed near the heat exchanger 6, and when this thickness reaches a predetermined value, the control device detects the thickness of the frost that has adhered to the upstream surface of the heat exchanger 6. , the compressor 21 and fan 7 are turned off, and the switch 24 is turned on. In addition, electric heater 19 for defrosting
When the heat exchanger 6 is energized, the frost adhering to the surface of the heat exchanger 6 melts and forms water droplets that fall to the bottom of the cooling chamber 5, but these water droplets are discharged to the outside by known means.

Since the heat exchanger 6 is configured as described above, the efficiency of the heat exchanger 6 can be improved and the occupied volume can be reduced, thereby making it possible to downsize the refrigerator. That is, since the integrally molded heat exchange tube body 11 is used, the heat exchange efficiency can be essentially improved. Also, the refrigerant pipe side fins 15.

The heater tube side fins 16 are provided to protrude in a direction different from the meandering direction of the heat exchange tube body 11 . Therefore, the height of each fin 15,16 does not affect the meandering. Therefore, the surface area of each fin 15, 16 can be set freely, and the meandering pitch can also be made sufficiently narrow. Therefore, the occupied volume can be reduced.

In addition, the refrigerant pipe side fins 15 and the heater pipe side fins 16
A strip-shaped fin piece 17.1 having a constant width in the tube axis direction
These strip-shaped fin pieces 17 and 18 are each divided into units W having a larger strip-shaped fin ordinal number as they are located on the upstream side with respect to the air flow direction Y, and each of these units W is bent. Since the arrangement is such that a plurality of unit rows are formed approximately parallel to the air flow direction Y, the units W located on the upstream side have a low cooling effect, and as a result, frost formation occurs along the air flow direction. Uniformity can be achieved. Therefore, the defrosting interval can be lengthened. In other words, the heat transfer coefficient α3 of a flat plate placed parallel to the flow is:
It is expressed by the following formula.

α8-(0,664λ 4)/P where λ is the heat transfer coefficient of air, P is the pitch, Re is the Reynolds number, and P is the Prandtl number.

As can be seen from this equation, the heat transfer coefficient can be easily controlled by changing the pitch. Therefore, if the width of the unit W is set on the upstream side, that is, in a place where frost is more likely to form, the pitch is larger, so that frost is formed almost uniformly along the air flow direction Y. You will be able to do that. For this reason, the defrosting interval can be lengthened, so energy savings can be achieved.

Furthermore, the length from the root to the tip of the heater tube side fin 16 is shorter than the length from the root to the tip of the refrigerant tube side fin 15 by the amount that the heater tube 14 is present. The cooling effect on the fin 15 side and the fin roller side can be set equally with respect to the center of the fin 12 as a boundary. therefore,
The surfaces of the refrigerant tube side fins 15 and the heater tube side fins 16 can be frosted to a uniform thickness, thereby making it possible to further lengthen the defrosting interval. Furthermore, since the heater pipe 14 is thermally brought into close contact with the refrigerant pipe 12, the heat generated by the defrosting electric heater 19 can be efficiently transmitted to the refrigerant pipe 12, and as a result, the defrosting energy is further reduced. It is possible to reduce the amount. Further, in order to form the above-mentioned unit W, a strip-shaped fin piece 17 of a constant width is provided.
18 is formed and this is divided into sections,
The notch can be formed by machining. Therefore, manufacturing can be facilitated, and as a result, the effects of the present invention described above can be achieved.

Note that the present invention is not limited to the embodiments described above, and can be modified in various ways. That is, the refrigerant tube-side fins 15 and the heater tube-side fins 16 may be rolled to make them thinner, increasing the surface area of each fin, and greatly increasing heat exchange efficiency with a small amount of material. Furthermore, as shown in FIG.
may be twisted parallel to the flow direction Y.

In this case, as shown in FIG. 6, each unit W may be alternately bent into a V-shape and then twisted at its base so that it is parallel to the air flow direction. Further, in order to reduce pressure loss, the strip-shaped fin piece W located at the bent portion Q may be removed.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a fan-cool type refrigerator incorporating a heat exchanger according to an embodiment of the present invention. Figure 2 shows internal cooling yi
Figure 3 is a perspective view showing the heat exchanger incorporated in the heat exchanger taken out; Figure 4 is a perspective view showing the heat exchange tube partially taken out, and Figure 4 There are also diagrams for explaining the manufacturing process of the exchanger, and Figures 5 and 6 for explaining modified examples of the present invention. 1...Refrigerating room, 5...Cooling, 6...Heat exchanger,
7... Fan, 11... Heat exchange tube, 12...
Refrigerant pipe, 13... Connection part, 14... Heater 9t, 15
=- Refrigerant pipe side fin, 16... Heater pipe side fin,
17.18...Strip-shaped fin piece, 1...Electric heater for defrosting, W...Unit. Applicant's representative Patent attorney Takehiko Suzue? 631 Figure 2 Figure 3 Figure 4 (a) (b)

Claims (2)

[Claims] (1) A refrigerant pipe, a heater pipe that is connected in parallel to the refrigerant pipe via a strip-shaped connection part and into which an electric heater for defrosting is inserted; refrigerant tube side fins and heater tube side fins that are shorter than the length from the root to the tip of the refrigerant tube side fins, each protruding on a line connecting the center of the heater tube and the center of the refrigerant tube on the surface; A heat exchange tube formed by integral extrusion of aluminum is placed on a plane perpendicular to a line connecting the center of the refrigerant tube and the center of the heater tube, and with the refrigerant flowing through the refrigerant tube. The refrigerant tube side fins and the heater tube side fins are arranged in a meandering manner on a surface parallel to the flow direction of the heat exchange fluid to be heat exchanged, and each of the refrigerant tube side fins and the heater tube side fins has a width in the tube axis direction. The fins are separated into a fixed plurality of strip-shaped fin pieces, and each strip-shaped fin piece is divided into a plurality of units in which the number of strip-shaped fin pieces is larger as the fin pieces are located on the upstream side based on the flow direction of the heat exchange fluid. A refrigeration machine characterized in that the base portions of the units are bent or twisted so that the tips of adjacent units in the tube axis direction are separated from each other and substantially parallel to the flow direction of the heat exchange fluid. heat exchanger. (2) The refrigeration machine according to claim 1, wherein the strip-shaped fin piece located at the bent portion formed by the meandering of the heat exchange tube body is removed. heat exchanger.