ES2955923T3 - Heat exchanger - Google Patents

Abstract

The purpose is to ensure evaporation capacity by suppressing heat transfer loss when there is a deviation in frosting advancing from a front row and a deviation in refrigerant distribution from a header to the flat tubes. A heat exchanger 1 comprises a plurality of flat tubes 11, fins 12 arranged on the flat tubes 11 and a header 13 (or 23) placed in the vertical direction D1 in which the flat tubes 11 are stacked and connected to the flat tubes. 11. , and the heat exchanger works as an evaporator that causes heat to be exchanged between the air and the refrigerant that flows into the flat tubes 11 through the header and causes the refrigerant to evaporate. A front row heat exchange element 10 comprising flat tubes 11, fins 12 and the head 13, and a rear row heat exchange element 20 comprising flat tubes 11, fins 12 and the head 23 are arranged. The cross-sectional area of the flow channel of the front row header 13 placed in the front row F is less than the cross-sectional area of the flow channel of the rear row header 23 placed in the rear row R so that the flow rate of the coolant flowing in the header of the front row 13 is greater than the flow rate of the coolant flowing in the header of the rear row 23. (Automatic translation with Google Translate, without legal value)

Description

DESCRIPTION

Heat exchanger

Technical field

The present invention relates to a heat exchanger used in, for example, an air conditioner, a freezer, a transport freezer and a water heater.

Background of the technique

A heat exchanger in which a refrigerant flows through each of a plurality of stacked flat tubes is used in an appliance such as an air conditioner and a freezer, and constitutes a refrigerant circuit of the appliance.

The heat exchanger has a configuration in which the plurality of flat tubes are assembled into a corrugated or plate-shaped fin and a pair of headers. Both end portions of each of the flat tubes are connected to the respective headers, and the refrigerant introduced into the headers from a pipe of the refrigerant circuit is distributed to each of the flat tubes. Heat is exchanged between the coolant flowing through the flat tubes and the air flowing into the gaps between the fins and the flat tubes from a direction orthogonal to the coolant flow.

In case the heat exchanger functions as an evaporator, the refrigerant from a two-phase gas-liquid flow flows to the headers. Within the headers, the distribution of a gas phase refrigerant and a liquid phase refrigerant having a density greater than the density of the gas phase refrigerant easily deviates in a stacking direction of the flat tubes. Therefore, a distribution state of the refrigerant to each of the flat tubes is easily deviated.

To uniform the amount of heat transfer throughout the stacked body, including the flat tubes and fins, in addition to uniform said state of coolant distribution and, consequently, achieve the necessary performance sufficiently, establishment of paths through which coolant flows efficiently in the headers and flat tubes, a configuration of each of the headers, a shape of each of the fins and the like have been devised in various ways.

To ensure a heat transfer area necessary for a predetermined heat exchange performance, a plurality of rows of heat exchange elements (each of the sets including flat tubes and fins) are arranged in a direction connecting one side of windward and a leeward side in some cases (e.g. Patent Bibliography 1).

In patent literature 1, an individual header is not provided on the windward side (front row) and the leeward side (rear row), and the flat tubes in the front row and the flat tubes in the rear row are connected to common heads. A large number of horizontal dividing plates are provided within each of the headers. The flat tube of the front row and the flat tube of the rear row in the same area in the stacking direction of the flat tubes communicate with the same section divided by the horizontal dividing plates. The refrigerant that has flowed from the refrigerant pipe to each of the sections within each of the headers flows through the flat tubes in the front row and the rear row in each zone.

Patent literature 2 discloses a heat exchanger according to the preamble of claim 1.

Appointment list

Patent bibliography

Patent Bibliography 1: JP 5840291 B2

Patent Bibliography 2: WO2016/121123A1

Summary of the invention

technical problem

When the large number of dividing plates is provided inside each of the headers, the heat transfer loss caused by the deviation of coolant distribution can be suppressed, but the number of parts is increased. Even in the case that the heads are shared by the front row and the rear row as in patent literature 1, the dividing plates corresponding to the number of zones are still necessary, and the number of parts is increased. Therefore, it is preferable to avoid the interior of each of the heads being finely divided by the dividing plates.

Furthermore, in the heat exchanger that functions as an evaporator in winter, frost progresses from the rear row which has a very different temperature from that of the air. Therefore, the frost state deviation between the front row and the back row cannot be avoided. Therefore, if an air passage with frost is closed in the front row and the air flow rate in the rear row is reduced, the rear row that can carry out heat exchange because the amount of frost is still small cannot operate sooner. .

Accordingly, an object of the present invention is to provide a heat exchanger that can ensure evaporation performance while suppressing heat transfer loss in a state in which there is deflection of frost advancing from the front row and deflection of the refrigerant distribution from the headers to each of the flat tubes.

Solution to the problem

A first heat exchanger according to the present invention is a heat exchanger that includes a plurality of stacked flat tubes, fins arranged on the flat tubes, and headers erected in a stacking direction in which the flat tubes are stacked. and connect to flat tubes. The heat exchanger works as an evaporator that causes heat exchange between the air and the refrigerant flowing into the flat tubes through the headers, to evaporate the refrigerant. Heat exchange elements, each including flat tubes, fins and headers, are arranged in a front row located on an upstream side of the air flow and a rear row located on a downstream side of the air flow. air flow. The cross-sectional area of the flow path of each of the front row headers that are the headers in the front row is smaller than the cross-sectional area of the flow path of each of the back row headers which are the headers in the back row, such that a flow rate of the coolant flowing through each of the front row headers is greater than a flow rate of the coolant flowing through each of the headers back row.

The first heat exchanger according to the present invention preferably further includes a dividing portion configured to divide the interior of at least any of the front row headers and the rear row headers by extending in the stacking direction, and the area of Cross section of the flow path is preferably established by the dividing portion.

In the first heat exchanger according to the present invention, a width of each of the flat tubes in the rear row in the air flow direction is preferably wider than the width of each of the flat tubes in the row. front in the direction of air flow.

In the first heat exchanger according to the present invention, the heat exchange elements preferably include two or more heat exchange elements connected in series, and one heat exchange element of the heat exchange elements on the side. further downstream it is preferably located in the front row.

In the first heat exchanger according to the present invention, the heat exchange elements preferably include three or more heat exchange elements connected in series, and one heat exchange element of the heat exchange elements on the side. further upstream it is preferably located in the front row.

Advantageous effects of the invention

According to the present invention, as described below, a heat transfer amount can be balanced in the stacking direction (up and down direction) of the flat tubes as a whole of the front row and the back row. . Therefore, even when the divider plate is not provided for uniformization of refrigerant distribution, the deterioration of heat exchange performance due to deviation of refrigerant distribution can be avoided. Additionally, even in an operating state where frost occurs, a time may be extended before the operation switches to defrosting operation while the heat exchange capacity remains at least on one lower zone side in the back row.

Brief description of the drawings

[Figure 1] Figure 1 is a perspective view schematically illustrating a heat exchanger according to a first embodiment.

[Figure 2] Figure 2 is a schematic diagram to explain the difference between the flow rate of a refrigerant flowing through a front row header and the flow rate of a refrigerant flowing through a row header rear illustrated in figure 1.

[Figures 3A to 3C] Figures 3A to 3C are graphs illustrating a state of distribution of a liquid phase refrigerant to flat tubes in each of the front and rear rows at the respective refrigerant flow rates.

[Figure 4] Figure 4 is a schematic diagram to explain the action of the heat exchanger illustrated in Figure 1.

[Figure 5] Figure 5 is a schematic diagram illustrating a front row header and a rear row header according to a modification of the first embodiment.

[Figure 6] Figure 6 is a schematic diagram illustrating a heat exchange element in a front row and a heat exchange element in a rear row according to another modification of the first embodiment.

[Figures 7A to 7D] Figure 7A is a schematic diagram illustrating a heat exchanger according to a second embodiment, Figure 7B is a schematic diagram illustrating a heat exchanger according to a modification of the second embodiment, and Figures 7C and 7D are diagrams illustrating the distribution of refrigerant in liquid phase in a case where dryness is high.

[FIGS. 8A and 8B] Figure 8A is a schematic diagram illustrating a heat exchanger according to a third embodiment not in accordance with the invention, and Figure 8B is a schematic diagram illustrating a modification of the third embodiment.

[FIGS. 9A and 9B] Figures 9A and 9B are schematic diagrams each illustrating a heat exchanger according to a fourth embodiment, which is not in accordance with the invention, without illustration of fins.

Description of the achievements

Some embodiments of the present invention are described below with reference to the accompanying drawings.

[First realization]

A heat exchanger 1 illustrated in Figure 1 includes a front row heat exchange element 10 and a rear row heat exchange element 20. The heat exchanger 1 constitutes a refrigerant circuit of an air conditioner, a freezer , a water heater, or similar. The refrigerant circuit includes a compressor, a condenser, a decompression unit, and heat exchanger 1 which serves as an evaporator.

As described below, the heat exchanger 1 according to the present embodiment suppresses the deterioration of heat exchange performance while accepting the deviation of refrigerant distribution from the headers 13 and 23 to each of the flat tubes. 11 and frost diversion.

(Heat exchange element)

The front row heat exchange element 10 includes the plurality of stacked flat tubes 11 (tubes), a plurality of fins 12 and a pair of front row headers 13 (13A and 13B) connected to the flat tubes 11.

The front row heat exchange element 10 exchanges heat between a coolant flowing into each of the flat tubes 11 through one (13A) of the front row headers 13 and air flowing into the gaps between the fins. 12 and the flat tubes 11 from a direction orthogonal to the flat tubes 11.

As with the front row heat exchange element 10, the rear row heat exchange element 20 includes the plurality of stacked flat tubes 11, the plurality of fins 12 and the pair of rear row headers 23 (23A and 23B) connected to the flat tubes 11. The rear row heat exchange element 20 exchanges heat between a refrigerant flowing to each of the flat tubes 11 through one (23A) of the rear row headers 23 and the air.

The flat tubes 11 and the fin 12 are common components to the front row heat exchange element 10 and the rear row heat exchange element 20.

In this example, a direction in which the flat tubes 11 are stacked (stacking direction) is called the up and down direction DI.

Furthermore, in the flow of air subjected to heat exchange with the refrigerant flowing through the flat tubes 11, an upstream side is called "front" and a downstream side is called "rear". The air drawn by a non-illustrated fan or the like is preferably supplied to an entire region of the heat exchanger 1.

The front row heat exchange element 10 and the rear row heat exchange element 20 are arranged in the direction of air flow (illustrated by the empty arrow). In each of the drawings, the front row is indicated by an "F" and the back row is indicated by an "R."

The front row heat exchange element 10 and the rear row heat exchange element 20 are connected to refrigerant circuit pipes in parallel. The coolant of the same flow rate flows through the front row heat exchange element 10 and the rear row heat exchange element 20.

The heat exchanger 1 includes the heat exchange elements 10 and 20 in at least a portion thereof. The heat exchanger 1 may include, but is not illustrated, another heat exchange element in addition to the heat exchange elements 10 and 20.

(flat tube)

Each of the flat tubes 11 is a flat tube through which the refrigerant flows, has a predetermined length and extends linearly. Both end portions of each of the flat tubes 11 are connected to the respective headers 13 (or respective headers 23). Each of the heads 13 and 23 includes insertion holes (not shown), each of which receives the corresponding end portion of the flat tubes 11 inside the heads 13 and 23.

The plurality of flat tubes 11 are stacked parallel to each other with predetermined intervals in the upward and downward direction D1. The end portions of each of the flat tubes 11 open into the respective headers 13 (or respective headers 23).

(Fin)

Each of the fins 12 according to the present embodiment has a substantially rectangular plate-like exterior shape, and are provided on the flat tubes 11 to increase the surface area that comes into contact with air.

Each of the fins 12 includes a plurality of notches 121 into which the respective flat tubes 11 are inserted.

The fins 12 of the front row F and the fins 12 of the rear row R may have different shapes.

Figure 1 illustrates only a part of the fins 12 in each of the front row F and the rear row R. The large number of fins 12 are actually provided in the stacked body of the flat tubes 11 with intervals in the longitudinal direction of the flat tubes 11 in each of the front F and rear R rows.

Instead of the plate-shaped fins 12, the other type of fins can be provided on the flat tubes 11. For example, a corrugated fin can be provided between the adjacent flat tubes 11 in the up and down direction D1.

The members configuring the heat exchanger 1, such as the flat tubes 11, the fins 12, the front row headers 13 and the rear row headers 23, are made of a metallic material such as an aluminum alloy and a metal alloy. copper. These members are integrated using a joining material, such as a brazing filler metal, to constitute the heat exchanger 1.

(front row head)

The pair of front row headers 13 are erected in the stacking direction (D1) of the flat tubes 11 in the front row F. The flat tubes 11 in the front row F are connected to these front row headers 13. Each The front row head pair 13 has a cylindrical shape and has a closed upper end and a closed lower end.

The coolant flows to each of the flat tubes 11 through one (13A) of the pair of front row headers 13, and the coolant flows to the other (13B) of the pair of front row headers 13 from each of the flat tubes 11.

The front row header 13A includes an introduction portion 131 that introduces coolant from a non-illustrated coolant pipe or the like into the interior of the front row header 13. The interior of the front row header 13A serves as a flow path through from which the refrigerant introduced through the introduction portion 131 flows upward.

The introduction portion 131 is preferably located below the flat tube 11 which is arranged at the lowest part within the front row header 13A because a gas phase refrigerant floating from the introduction portion introduction 131 and a liquid refrigerant rising together with the gas phase refrigerant can flow in all the flat tubes 11, including the flat tube 11 arranged in the lowest part of the front row F.

The coolant introduced into the front row header 13A is distributed and flows to each of the flat tubes 11 in the front row F. In addition, heat is exchanged between the air passing through the gaps (air passages) between the fins 12 and the flat tubes 11 and the refrigerant inside the flat tubes 11 while the coolant flows through each of the flat tubes 11 (dashed arrows in Figure 1). At this time, the refrigerant flowing through the flat tubes 11 evaporates by absorbing heat from the air.

The refrigerant that has flowed through each of the flat tubes 11 is combined inside the front row header 13B, and the combined refrigerant exits the front row header 13B to a refrigerant pipe or the like outside the heat exchanger 1. Alternatively, in case the heat exchanger 1 includes the other heat exchange element connected to the front row header 13B, the refrigerant exits from the front row header 13B to the other heat exchange element.

(Rear row head)

The rear row headers 23 are briefly described because the rear row headers 23 have a configuration similar to the configuration of the front row headers 13, except that each of the rear row headers 23 has a cross-sectional area of the flow path different from a cross-sectional area of the flow path of each of the front row headers 13.

The coolant flows to each of the flat tubes 11 in the rear row R through one (23A) of the pair of rear row headers 23, and the coolant flows to the other (23B) of the pair of rear row headers 23 of each of the flat tubes 11 in the rear row R.

The rear row header 23A includes an introduction portion 231 that introduces refrigerant from a refrigerant pipe or the like into the interior of the rear row header 23.

The refrigerant introduced into the rear row header 23A through the introduction portion 231 is distributed and flows into each of the flat tubes 11 in the rear row R. The refrigerant flowing through each of the flat tubes 11 in the rear row R undergoes heat exchange with the air passing through the front row F. Thereafter, the refrigerant is combined within the rear row header 23B, and the combined refrigerant exits the rear row header 23B to a refrigerant pipe outside heat exchanger 1 or to the other heat exchange element.

The heat exchanger 1 is basically used in a state in which the front row headers 13 and the rear row headers 23 are arranged along the up and down direction D1 (vertical direction). At this time, the flat tubes 11 extend in the horizontal direction and are stacked in the up and down direction D1.

Note that the front row headers 13 and the rear row headers 23 may be slightly inclined with respect to the up and down direction D1.

(Main features of the present embodiment)

The present embodiment is mainly characterized in that the cross-sectional area of the flow path Af (Figure 2) of each of the front row headers 13 is smaller than the cross-sectional area of the flow path Ar (Figure 2 ) of each of the rear row headers 23 such that the flow rate of the coolant flowing through each of the front row headers 13 is greater than the flow rate of the coolant flowing through each of the rear row headers 23.

Each of the front row headers 13 and the rear row headers 23 according to the present embodiment includes a flow path having a circular cross section, and an inner diameter of each of the front row headers 13 is smaller than an inner diameter of each of the rear row heads 23.

Note that the cross-sectional shape of each of the front row headers 13 and the rear row headers 23 may have an optional shape such as a rectangular shape and an elliptical shape.

As illustrated in Figure 5, the appropriate flow path cross-sectional areas Af and Ar can be established by respectively installing vertical divider plates 14 and 24 within the front row header 13 and the rear row header 23. Only You can install any of the 14 and 24 vertical divider plates.

The vertical dividing plate 14 is erected along the up and down direction D1 orthogonally to a paper surface of Figure 5, and divides the interior of the front row header 13 into a section 141 on the side of the portion introduction 131 and a section 142 on the side of the flat tubes 11.

The coolant introduced from the introduction portion 131 in the section 141 flows to the section 142 through an opening 14A that penetrates a lower end portion of the vertical dividing plate 14 in the thickness direction and is distributed to each of the flat tubes 11 while flowing upward within the section 142.

The vertical divider plate 24 has a similar configuration to the vertical divider plate 14 described above, and divides the interior of the rear row header 23 into a section 241 on the side of the introduction portion 231 and a section 242 on the side of the flat tubes 11. An opening 24A is provided in a lower end portion of the vertical dividing plate 24.

When the positions of the vertical dividing plates 14 and 24 are set so that a dimension G2 of a gap between the vertical dividing plate 24 and the end portion of each of the flat tubes 11 is greater than a dimension G1 of a gap between the vertical dividing plate plate 14 and each of the flat tubes 11, the cross-sectional area of the flow path Ar which is greater than the cross-sectional area of the flow path Af of the row head section 142 front 13 can be provided to section 242 of the rear row headers 23.

(Action for this realization)

As illustrated in Figure 2, the coolant after flowing, at the predetermined flow rate, from the coolant circuit pipe to the front row header 13A through the introduction portion 131 is distributed to each of the flat tubes 11 in the front row while flowing upward into the front row header 13A at the flow velocity Vf corresponding to the cross-sectional area of the flow path Af of the front row header 13A.

In contrast, the coolant after flowing, at the same rate as the flow rate of the coolant flowing into the introduction portion 131 of the front row header 13A, from the coolant circuit pipe to the rear row header 23A through the portion introduction 231 is distributed to each of the flat tubes 11 in the rear row while flowing upward into the rear row header 23A at the flow velocity Vr corresponding to the cross-sectional area of the flow path Ar of the row header rear 23A.

At this time, since the flow rate of the coolant flowing into the front row header 13 through the introduction portion 131 and the flow rate of the coolant flowing into the rear row header 23 through the introduction portion 231 are equal to each other and Af < Ar is satisfied for the cross-sectional areas of the flow path, Vf > Vr is established for the flow velocities.

In other words, the flow rate Vf of the refrigerant flowing through the front row header 13A is greater than the flow rate Vr of the refrigerant flowing through the rear row header 23A.

The lengths of the arrows illustrated in gray in Figure 2 schematically represent relative magnitudes of the flow velocities Vf and Vr.

The refrigerant of a two-phase gas-liquid flow expanded by passing through the decompression unit of the refrigerant circuit flows to the front row header 13A and the rear row header 23A. A gas phase component of the refrigerant is called a gas phase refrigerant, and a liquid phase component of the refrigerant is called a liquid phase refrigerant. The liquid phase refrigerant is transported upward by being trapped in the floating gas phase refrigerant. The density of the refrigerant in the liquid phase is greater than the density of the refrigerant in the gas phase. Therefore, the distribution of the gas phase refrigerant and the liquid phase refrigerant in the up and down direction D1 is easily diverted in each of the front row header 13a and the rear row header 23A.

Such a distribution state of the gas phase refrigerant and the liquid phase refrigerant is different between the front row header 13A and the rear row header 23A based on the difference between the flow rates Vf and Vr.

In the front row header 13A which has the highest flow rate Vf, the liquid phase refrigerant is transported to a higher part compared to the rear row header 23A which has a relatively low flow rate Vr. Accordingly, a percentage of the liquid phase refrigerant to the gas phase refrigerant is relatively high at the top of the flow path from a lower end to an upper end of the front row header 13A, and the percentage of the liquid phase refrigerant the gas phase refrigerant is low at a lower part of the flow path. The liquid phase refrigerant that makes a phase transition to the gas phase while flowing through the flat tubes 11 absorbs heat from the air based on the latent heat. When the flow rate of the liquid phase refrigerant is high, the amount of heat transfer between the air and the refrigerant is large.

A width of each of the gray arrows illustrated in Figure 2 represents the percentage of refrigerant in the liquid phase with respect to the refrigerant in the gas phase as a function of the flow rate. In the front row header 13A, the Liquid phase coolant flow percentage gradually increases as it rises from a lower side.

In contrast, in the rear row header 23A which has the low flow rate Vr, the liquid phase coolant is difficult to bring to the top compared to the front row header 13A. Therefore, a range in which the liquid phase refrigerant is sufficiently transported from the introduction portion 231 is limited to the bottom of the flow path of the rear row header 23A.

Therefore, unlike the front row header 13A described above, the percentage of liquid phase refrigerant to gas phase refrigerant is high at the bottom of the flow path of the rear row header 23A, and the percentage of refrigerant liquid phase to gas phase refrigerant is low at the top of the flow path.

Therefore, both in the distribution state of the liquid phase refrigerant distributed from the front row header 13A to each of the flat tubes 11 in the front row F and in the distribution state of the liquid phase refrigerant distributed from the header from rear row 23A to each of the flat tubes 11 in the rear row R, the deviation in the upward and downward direction D1 is found in different ways.

Figures 3A to 3C respectively illustrate the percentage of liquid phase refrigerant flow (ratio of flow to gas phase refrigerant) in the refrigerant that has flowed into the flat tubes 11 in each of the front row F and the rear row R based on the experimental results in a case of Figure 3A where the flow rate of the refrigerant introduced into the heat exchanger 1 is small, in a case of Figure 3B where the flow rate is medium, and in a case of Figure 3C where the flow is large. The numbers 1, 2, 3... are provided to the flat tubes 11 in order from the topmost flat tube 11 to the bottom located flat tube 11 in each of the front row header 13A and the rear row header 23A. It should be noted that in the experiment to obtain the data in Figures 3A to 3C, one front row heat exchange element and one rear row heat exchange element were used, each of which included seven flat tubes 11 .

Figures 3A to 3C illustrate a trend similar to the previous description, specifically, a tendency for the percentage of liquid phase refrigerant flowing inward to be high in the flat tube 11 located at the top of the front row F, while the percentage of liquid phase coolant flowing in is high in the flat tube 11 located at the bottom of the rear row R.

As illustrated in Figures 3A to 3C, the degree of deviation of the liquid phase coolant flow rate percentage in the up and down direction D1 in the front row F increases as the coolant flow rate increases. In contrast, the degree of deviation of liquid phase coolant flow percentage in the up and down direction D1 in the rear row R decreases as the coolant flow rate increases. The trend is established qualitatively because the cross-sectional area of the flow path of each of the front row headers 13 is smaller than the cross-sectional area of the flow path of each of the rear row headers 23 .

As the flow rate relative to Figure 3C, the flow rate of the heat exchanger 1 in a situation where frost is easily formed, for example, in a situation where the air conditioner performs heating operation in winter, is assumed. When the flow rate is large as described before, the uneven distribution of the liquid phase coolant at the top of the front row F becomes noticeable as illustrated in Figure 3C. At this time, in the heat exchange element 10 in the front row F, the heat exchange is mainly carried out in an upper area.

(Effects of this realization)

In the present embodiment, as described above, the cross-sectional area of the flow path Af of each of the front row headers 13 and the cross-sectional area of the flow path Ar of each of the headers of rear row 23 are made different from each other to provide a different distribution to the liquid phase refrigerants in the front row F and in the rear row R. This suppresses the heat transfer loss and ensures the heat exchange performance as a all of heat exchanger 1.

The action of the present embodiment is described with reference to Figure 4 and Figure 2. According to the present embodiment, even when the deviation is present in the percentage of liquid phase flow of the refrigerant distributed to each of the flat tubes 11 in each of the front row F and the rear row R, the heat transfer amount is uniformized and the necessary heat exchange performance is ensured even under capacity restriction of the heat exchanger or the like, as a whole of the heat exchanger 1.

In the front row header 13 (Figure 2) which has the high flow rate, the liquid phase coolant is sufficiently brought to the top. Therefore, the amount of heat transfer between the air and the refrigerant flowing through the flat tube 11 on the upper zone side which has the large percentage of liquid phase refrigerant flow between the flat tubes 11 in the row front F to which the coolant is distributed from the front row header 13 is large, while the amount of heat transfer at the bottom is small.

In contrast, in the rear row header 23 (Figure 2) which has a flow rate lower than the flow rate of the front row header 13, the liquid phase coolant is not sufficiently brought to the top. Therefore, the amount of heat transfer between the air and the refrigerant flowing through the flat tube 11 on the lower zone side which has the large percentage of liquid phase refrigerant flow between the flat tubes 11 in the row rear R to which the coolant is distributed from the rear row header 23 is large, while the amount of heat transfer at the top is small.

The air flowing along an arrow 1 illustrated in Figure 4 passes through the lower zone side having the small heat transfer amount in the front row F and the lower zone side having the small heat transfer amount large heat flow in the rear row R. At this time, even if the heat of the air that has passed through the lower zone side that has the low flow rate of liquid phase refrigerant in the front row sufficient to the refrigerant, an amount of liquid phase refrigerant flowing through the flat tubes 11 on the lower zone side in the rear row R in which the air subsequently flows to the front row F is sufficient to dissipate heat from air.

Furthermore, the air flowing along an arrow 2 illustrated in Figure 4 passes through the upper zone side having the large amount of heat transfer in the front row F and the upper zone side having the small amount of heat transfer in the rear row R. In this case, the air, whose heat has already been dissipated to the refrigerant that has the high percentage of liquid phase refrigerant flow in the upper zone side of the front row F, flows to the rear row R. Therefore, it is sufficient for the liquid phase refrigerant in an amount sufficient to exchange heat with the air after heat dissipation in the front row F to flow through the flat tubes 11 in the side of upper zone in the rear row R.

Accordingly, the heat transfer surface is effectively utilized while heat transfer loss is avoided throughout the heat exchanger 1, including the upper zone side and the lower zone side of the front row F and the upper zone side and the lower zone side of the rear row R. Therefore, even when the heat exchanger 1 is small, it is possible to sufficiently ensure the heat exchange performance. The flow rate is made different between the front row header 13 and the rear row header 23 as in the present embodiment, which makes it possible to balance the amount of heat transfer in the up and down direction D1 as the whole of the front row F and the back row R as described above. This can prevent the deterioration of heat exchange performance due to deviation of refrigerant distribution. As a result, it is not necessary to provide the horizontal divider plate in each of the heads 13 and 23 to uniform the distribution of the coolant. This makes it possible to avoid increasing the number of parts and eliminate the manufacturing cost of the heat exchanger 1.

Contrary to the present embodiment, even in the case that the cross-sectional areas of the flow path are determined to set Af > Ar, and the flow speed Vf of the front row header 13 becomes lower than the speed of flow Vr of the rear row header 23, effects similar to the purposes of the present embodiment can be achieved in terms of avoiding performance deterioration due to deviation of coolant distribution.

Furthermore, the present embodiment addresses the performance deterioration caused by frost in addition to the performance deterioration caused by the deviation of refrigerant distribution. When the temperature of external air as heat source is low during heating operation, frost progresses from the front row F which has a very different temperature with the contact air compared to the rear row R in heat exchanger 1 used in an external heat exchanger of air conditioning. Alternatively, frost may occur on the heat exchanger 1 used to cool a heat load, for example, a heat exchanger within a refrigerator/freezer such as a refrigeration/freezing display case. Also in this case, the frost advances from the front row F.

To avoid performance deterioration caused by frost, it is preferable that the relationship between the flow rate Vf of the front row header 13 and the flow rate Vr of the rear row header 23 be specified such that the flow rate Vf of the front row header 13 is greater than the flow rate Vr of the rear row header 23, as with the present embodiment. Furthermore, in the present embodiment where refrigerant at the same flow rate is introduced into each of the front F and rear R rows, the cross-sectional areas of the flow path are specified for Af < Ar.

In the upper zone side that has a large percentage of liquid phase refrigerant flow in the front row F, where frost easily occurs, frost easily occurs because the air is sufficiently cooled by the refrigerant that has the large percentage refrigerant flow rate in liquid phase. In contrast, hardly any frost occurs on the lower zone side, even in the front row up and down D1 in the front row (e.g., figure 3C).

It is assumed that the frost on the upper zone side in the front row F which has a large flow rate of the liquid phase refrigerant progresses as illustrated in Figure 3C and the air flow rate on the upper zone side in the rear row R is reduced due to the closure of the air passage caused by frost. At this time, however, the frost does not progress much on the lower zone side in the front row F. Therefore, the air flow can be maintained at least on the lower zone side in the leeward rear row R on the lower zone side in the front row F.

In other words, after the heat exchange capacity on the upper zone side including the rear row R is lost due to frost, air is fed to the rear row R on the lower zone side. Since the heat exchange capacity remains on the heat transfer surface on the lower zone side in the rear row R where no frost adheres, it is extended for a period of time before the operation switches to defrosting operation. .

According to the present embodiment, suppression of the heat transmission loss caused by frost makes it possible to avoid interruption of the heating operation or the like by the defrosting operation, and to continue the heating operation or the like.

Figure 6 illustrates an example in which each of the flat tubes 11 inserted into the rear row headers 23, each of which has a diameter greater than the diameter of each of the front row headers 13, has a width Dr wider than a width Df of each of the flat tubes 11 in the front row F. To increase the heat transfer area, the large width Dr of each of the flat tubes 11 in the direction of air flow substantially equal to the diameter of each of the rear row headers 23 is preferably secured. Expanding the width Dr of each of the flat tubes 11 in the rear row R allows the capacity of heat exchanger 1 to be improved without changing the space required for the installation of heat exchanger 1.

It should be noted that, instead of expanding the width Dr of each of the flat tubes 11 in the rear row R, two flat tubes 11 can be arranged in the width direction.

[Second realization]

Next, a second embodiment of the present invention is described with reference to Figures 7A to 7D.

In the second embodiment, an example of application to a heat exchanger that includes a plurality of paths connected in series is described.

A heat exchanger 2 illustrated in Figure 7A includes heat exchange elements 10 and 20 corresponding to the series connected paths. This is different from the heat exchange elements 10 and 20 which are connected to the parallel refrigerant circuit piping of the heat exchanger 1 according to the first embodiment.

Figure 7A schematically illustrates the heat exchange elements 10 and 20. Each of the heat exchange elements 10 and 20 has a similar configuration to the respective heat exchange elements 10 and 20 in the first embodiment (Figure 1). .

In other words, as illustrated in Figure 1, the front row heat exchange element 10 includes the flat tubes 11, the fins 12 and the front row headers 13. The rear row heat exchange element 20 also includes the flat tubes 11, the fins 12 and the rear row headers 23. Since the cross-sectional area of the flow path Af of each of the front row headers 13 is smaller than the cross-sectional area of the flow path Ar of each of the rear row headers 23, the coolant flow rate Vf of each of the front row headers 13 is greater than the coolant flow speed Vr of each of the front row headers back row 23.

As in the first embodiment, the amount of heat transfer in the upward and downward direction D1 as the entire front row F and the rear row R can be balanced based on the difference in flow speed, and The time before the operation switches to defrost operation when frost occurs may be prolonged.

The rear row heat exchange element 20 corresponds to a first path P1 on the most upstream side. The front row heat exchange element 10 corresponds to a second path P2 subsequent to the first path P1. In this example, the second path P2 is a path on the most downstream side.

The dryness of the coolant increases as the coolant flows from the most upstream path P1 to the most downstream path P2.

When the refrigerant is introduced from a non-illustrated refrigerant pipe to the rear row header 23A (Figure 1) of the first path P1, the refrigerant is distributed from the rear row header 23A to each of the flat tubes 11 in the row rear R. The coolant that has flowed through each of the flat tubes 11 is combines inside the rear row header 23B (Figure 1), and the combined refrigerant flows to the second path P2 in the front row F through a U-shaped pipe 17. Subsequently, the refrigerant is distributed from the row header front 13B (Figure 1) in the second path P2 to each of the flat tubes 11 in the flat row F, and the coolant that has flowed through each of the flat tubes 11 exits the front row header 13A (Figure 1) to the refrigerant pipe.

When the refrigerant absorbs heat from the air and the dryness of the refrigerant increases, an absolute amount of the liquid phase refrigerant flow rate is reduced. Therefore, it is particularly difficult to make the liquid phase refrigerant flow into the flat tube 11 on the upper zone side inside the header in the most downstream path P2.

Figure 7C and Figure 7D illustrate the distribution of refrigerant in liquid phase in a case where the dryness of the refrigerant is high, based on the experiment; However, the cross-sectional area of the flow path of a header is different in Figure 7C and Figure 7D. Figure 7C illustrates a case where the head has a typical flow path cross-sectional area (for example, the flow path cross-sectional area Am in Figure 8) and Figure 7D illustrates a case where which the cross-sectional area of the header flow path is smaller than the typical area. Since the coolant flow rate is the same in Figures 7C and 7D, the flow velocity within the header is higher in the header that has the small cross-sectional area of the flow path (Figure 7D). Therefore, compared to the head in which the flow rate is relatively low in Figure 7C, the liquid phase refrigerant reaches the flat tube 11 located at the top of the head illustrated in Figure 7D.

Based on the above description, the most downstream trajectory P2 where the dryness is the highest is arranged in the front row F as illustrated in Figure 7A. In the front row headers 13, where the flow rate is high due to the small cross-sectional area of the flow path, the liquid phase coolant can rise enough to the top to flow into the flat tube 11 located at the top. As a result, the heat transfer surface of the most downstream path P2 can be sufficiently used and can contribute to the performance.

[Modification of the second embodiment]

In a case where a heat exchanger 2A includes three or more paths connected in series as illustrated in Figure 7B, a fourth path P4 on the most downstream side is preferably arranged in the front row F and the first path P1 on the most upstream side it is also preferably arranged in the front row F as in the illustration of Figure 7A.

The second path P2 and a third path P3 are arranged in the rear row R.

Heat exchanger 2A includes the four paths P1 to P4. The first path P1 and the second path P2 on the upstream side are located at the bottom of the heat exchanger 2A, and the third path P3 and the fourth path P4 on the downstream side are located at the top in the exchanger heat 2A.

On the upstream side of a series circuit in heat exchanger 2A, the pressure loss in the same cross-sectional area of the flow path is less than the pressure loss on the downstream side because the in-phase refrigerant liquid is larger on the upstream side than on the downstream side where dryness increases. Accordingly, the cross-sectional area of the flow path of each of the paths P1 and P2 on the upstream side is suppressed (the number of zones is reduced (number of flat tubes 11)) to an extent that does not cause an excessive pressure loss compared to paths P3 and P4 on the downstream side, thus eliminating a heat exchanger height 2A.

Figure 7B also schematically illustrates the heat exchange elements 10 and 20. Each of the heat exchange elements 10 and 20 has a similar configuration to the respective heat exchange elements 10 and 20 in the first embodiment (Figure 1 ).

As in the first embodiment, the amount of heat transfer as the entire front row F and the rear row R can be balanced based on the flow rate difference between the front row headers 13 and the rear row headers 13. rear row 23, and the time before the operation switches to defrost operation when frost occurs may be extended.

When the coolant is introduced into the header 13A (Figure 1) of the first path P1 in the configuration illustrated in Figure 7B, the coolant is distributed from the front row header 13A to each of the flat tubes 11 in the front row F. The coolant that has flowed through each of the flat tubes 11 is combined within the front row header 13B (Figure 1), and the combined coolant flows to the second path P2 in the rear row R through a U-shaped pipe 181. Subsequently, the refrigerant is distributed from the rear row header 23B of the second path P2 to each of the flat tubes 11, and the refrigerant that has Fluid through each of the flat tubes 11 flows from the rear row header 23A to the rear row header 23A of the third path P3 on the upper zone side through a U-shaped pipe 182. Further , the refrigerant flows through the flat tubes 11 of the third path P3 and flows to the front row header 13B of the fourth path P4 through a U-shaped pipe 183. Subsequently, the refrigerant flows through the flat tubes 11 of the fourth path P4 and then flows into the refrigerant pipe.

According to the configuration illustrated in Figure 7B, the most downstream path P4 where the dryness is greatest is arranged in the front row F as in the second embodiment illustrated in Figure 7A. This makes it possible to sufficiently use the heat transfer surface of the most downstream path P4 and contribute to the performance.

Additionally, the cross-sectional area of the flow path is small at the header 13 in the most upstream path P1 where the pressure loss of the coolant is relatively small due to the lower dryness of the coolant flowing into the header 13. , in particular, in the head 13A as input of the path P1. This makes it possible to suppress the increase in evaporation temperature caused by the loss of refrigerant pressure. Suppressing the increase in evaporation temperature makes it possible to avoid deterioration in evaporation performance.

[Third realization]

A third embodiment is described below with reference to Figures 8A and 8B.

A heat exchanger 3 according to the third embodiment illustrated in Figure 8A includes the front row heat exchange element 10 and the rear row heat exchange element 20 as with the heat exchanger 1 (Figure 2) of according to the first embodiment.

In the first embodiment (Figure 2), the cross-sectional area of the flow path Af that is less than the cross-sectional area of the flow path Ar of the rear row header 23 is provided to the front row header 13 of such that the flow velocity Vf of the front row header 13 is greater than the flow velocity Vr of the rear row header 23. In contrast, in the third embodiment, a distributor 15 (flow rate adjustment unit) is used which You can adjust the flow rate of the coolant to be introduced into each front row header 13 and rear row header 23.

The distributor 15 including a capillary tube and the like divides the refrigerant flowing from the non-illustrated refrigerant pipe, at a predetermined flow ratio such that the flow rate Rf of the refrigerant flowing to the front row header 13 is greater than the flow rate Rr of coolant flowing to rear row header 23.

As a result, the flow velocity Vf corresponding to the flow rate Rf and the cross-sectional area of the flow path Am is provided to the front row header 13, and the flow velocity Vr corresponding to the flow rate Rr and the cross-sectional area of flow path Am is provided to rear row header 23.

In the present embodiment, since the cross-sectional area of the flow path Am of the front row header 13 and the cross-sectional area of the flow path Am of the rear row header 23 are equivalent to each other, Rf is set /Rr = Vf/Vr.

According to the present embodiment, the distributor 15 is provided. Therefore, even when the cross-sectional area of the flow path of the front row header 13 and the cross-sectional area of the flow path of the row header rear 23 are equivalent to each other, the coolant flow rate difference is provided to the front row header 13 and the rear row header 23, and the action and effects similar to the action and effects according to the first embodiment can be achieved based on the flow percentage distribution of liquid phase refrigerant in the up and down direction D1 caused by the difference in flow rate.

In addition, the use of the same headers with the same diameter makes it possible to avoid incorrect assembly of the front row heat exchange element 10 and the rear row heat exchange element 20 in the manufacture of the heat exchanger 3.

Instead of the distributor 15, a regulator 16 (flow adjustment unit) can be used as illustrated in Figure 8B. The regulator 16 is provided in a conduit introduced into the rear row header 23 from conduits divided at the equivalent flow rate of the non-illustrated refrigerant pipe. The pressure loss is provided by the regulator 16 to the refrigerant flowing to the rear row header 23. As a result, the flow rate Rr of the refrigerant introduced into the rear row header 23 is less than the flow rate Rf of the refrigerant introduced into the rear row header 23. front row 13.

[Fourth realization]

A fourth embodiment is described below with reference to Figures 9A and 9B.

Figures 9A and 9B each illustrate a heat exchanger 4 having the same configuration. The illustration in Figures 9A and 9B is different only in an image of the distribution of the refrigerant in the liquid phase.

The heat exchanger 4 according to the fourth embodiment includes two heat exchange elements 10 stacked in the up and down direction D1 in the front row F, and two heat exchange elements 20 stacked in the up and down direction down D1 in back row R.

In the heat exchanger 4, the front row heat exchange elements 10 and the rear row heat exchange elements 20 are arranged while moving in the up and down direction D1. Each of the front row heat exchange elements 10 and the rear row heat exchange elements 20 has the same height from a lower end to an upper end.

In addition, the front row heat exchange elements 10 and the rear row heat exchange elements 20 are connected to the refrigerant circuit pipe in parallel or in series, and the refrigerant of the same flow rate flows through the elements. front row heat exchange elements 10 and rear row heat exchange elements 20.

The heat exchanger 4 includes the front row heat exchange elements 10 and the rear row heat exchange elements 20, each of which has a similar configuration to the front row heat exchange element 10 and the rear row heat exchange element 20. rear row heat exchanger 20, respectively, according to the first embodiment. Unlike the first embodiment, however, the cross-sectional area of the flow path of each of the front row headers 13 and the cross-sectional area of the flow path of each of the rear row headers 23 are equivalent to each other.

Since the front row heat exchange elements 10 and the rear row heat exchange elements 20 move in the up and down direction D1, the positions of the introduction portions 131 connected to the front row headers 13 and the positions of the introduction portions 231 connected to the rear row headers 23 are different in the upward and downward direction D1.

In a case where the coolant flow rate is small or in a case where the dryness is high, the flow rate of the liquid phase coolant that has flowed into each of the heads 13 and 23 is low, as illustrated by gray arrows. depicting liquid phase refrigerant distribution images along the up and down direction D1 in Figure 9A. Therefore, the liquid phase coolant easily flows into the flat tubes 11 at the bottom, specifically, at the bottom zone side of each of the headers 13 and 23.

In contrast, in a case where the refrigerant flow rate is large or in a case where the dryness is low, the flow rate of the liquid refrigerant is high, as illustrated by gray arrows representing images of distribution of the refrigerant in liquid phase at along the up and down direction in Figure 9B. Therefore, the liquid phase coolant easily flows into the flat tubes 11 at the top, specifically, at the upper zone side of each of the headers 13 and 23.

As a result, as described with reference to Figure 4, the amount of heat transfer in the upward and downward direction D1 as the entire front row F and the rear row R can be balanced, and the time before The operation switching to defrosting operation when frost occurs may be prolonged.

In addition, the use of the same headers with the same diameter makes it possible to avoid incorrect assembly of the front row heat exchange elements 10 and the rear row heat exchange elements 20 in the manufacture of the heat exchanger 4.

In the fourth embodiment, the interior of the front row header 13 and the rear row header 23 can be divided into a plurality of sections, and introduction portions can be prepared that introduce the coolant into the respective sections. Also in this case, the introduction portions in the front row F and the introduction portions in the rear row R can have different height positions from each other by moving the front row heat exchange elements 10 and the heat exchange elements of rear row 20 in the up and down direction D1. Therefore, similar actions and effects can be achieved.

Apart from the foregoing description, the configurations described in the above-described embodiments may be appropriately selected or modified without departing from the scope of the present invention as defined in the appended claims.

For example, any of the heat exchangers according to the present invention may include one or more intermediate rows located between the front row F and the rear row R in addition to the front row F and the rear row R.

In each of the embodiments described above, each of the heat exchange elements 10 and 20 includes a line of flat tube element that includes the plurality of flat tubes 11 stacked in the up and down direction D1. The configuration is not limited to this, and each of the heat exchange elements according to the present invention may include two lines, namely, two flat tube elements arranged side by side in the direction of air flow, and These flat tube elements may be connected to the same headers.

List of reference signs

I to 4 Heat exchanger

10 Front row heat exchange element

I I Flat tube

12 Fin

13, 13A, 13B Front row header

14 Vertical dividing plate (dividing portion) 14A Opening

15 Distributor (flow adjustment unit)

16 Regulator (flow adjustment unit)

17 U-shaped pipe

20 Rear row heat exchange element

23, 23A, 23B Rear row header

24 Vertical dividing plate (dividing portion)

24A Opening

121 Notch

131 Introductory Portion

141 Section

142 Section

181, 182, 183 U-shaped pipe

231 Introductory Portion

241 Section

242 Section

Af, Ar, Am Flow path cross-sectional area

D1 Up and down direction

Df, Dr Ancho

F Front row

G1 Dimension

G2 Dimension

P1 to P4 Trajectory

R Back row

Rf, Rr Flow

Vf, Vr Flow rate

Claims (5)

1. A heat exchanger (1), comprising: a front row heat exchange element (10) and a rear row heat exchange element (20); the rear row heat exchange element (10) includes a plurality of stacked flat tubes (11); fins (12) provided on the flat tubes (11); and front row heads (13) erected in a stacking direction in which the flat tubes (11) are stacked, and connected to the flat tubes (11), where The front row heat exchange element (10) is configured to function as an evaporator that causes heat exchange between the air and a refrigerant that flows into the flat tubes (11) through the headers (13), to evaporate the refrigerant, the rear row heat exchange element (20) includes a plurality of stacked flat tubes (11); fins (12) provided on the flat tubes (11); and rear row headers (23) erected in a stacking direction in which the flat tubes (11) are stacked and connected to the flat tubes (11), the rear row heat exchange element (20) is configured to operate as an evaporator that causes heat exchange between air and a refrigerant that flows into the flat tubes (11) through the headers (23), to evaporate the refrigerant, The front row heat exchange element (10) and the rear row heat exchange element (20) are in use arranged in the direction of air flow with the front row heat exchange element (10) arranged in a front row (F) located on an upstream side of the air flow and the rear row heat exchange element (20) arranged in a rear row (R) located on a downstream side of the air flow, characterized because a cross-sectional area of the flow path (Af) of each of the front row headers (13) is less than a cross-sectional area of the flow path (Ar) of each of the rear row headers (23), the heat exchanger being configured so that the flow rate of the coolant flowing through each of the front row headers (13) is greater than the flow rate of the coolant flowing through each one of the rear row headers (23). 2. The heat exchanger according to claim 1, further comprising a dividing portion (14) configured to divide the interior of at least any of the front row headers (13) and the rear row headers (13) to extend in the direction of stacking, where The flow path cross-sectional area is established by the dividing portion (14). 3. The heat exchanger according to claim 1 or 2, wherein the width of each of the flat tubes (11) in the rear row (R) in the air flow direction is wider than the width of each of the flat tubes (11) in the front row (F) in the direction of air flow. 4. The heat exchanger according to any one of claims 1 to 3, wherein heat exchange elements include two or more heat exchange elements connected in series, and a heat exchange element of the heat exchange elements on the most downstream side is located in the front row (F). 5. The heat exchanger according to claim 4, wherein the heat exchange elements include three or more heat exchange elements connected in series, and one heat exchange element of the heat exchange elements in the most upstream side is located in the front row (F).