JPH11264630A - Air-conditioning equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the efficiency of an entire cycle, by providing a heat transfer pipe where a plurality of grooves that are not parallel are formed on an inside surface in an indoor heat exchanger, and at the same time by providing the heat transfer pipe where a spiral groove is formed on the inside surface in an outdoor heat exchanger. SOLUTION: Air-conditioning equipment is provided with outdoor and indoor heat exchangers with a heat transfer pipe where a refrigerant flows in the inside. In a heat transfer pipe 101 used for the indoor heat exchanger, grooves 14 that are not parallel and have a different direction mutually are formed, or the top part is formed in an uneven shape and a nearly wavy shape by the groove 104. Also, for a heat transfer pipe 102 for the outdoor heat exchanger, a spiral groove 103 is formed on the inside surface, thus locally thinning the thickness of the liquid film of a refrigerant liquid on the surface in the pipe, reducing the heat resistance between the refrigerant liquid and the outside of the heat transfer pipe, and hence increasing heat transfer efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat exchanger used for a refrigerator / air conditioner, and more particularly to a heat exchanger tube and a heat exchanger having a groove formed on an inner surface for promoting heat transfer, and a refrigerator / air conditioner.

[0002]

2. Description of the Related Art FIG. 5 is a perspective view of a conventional cross-fin tube heat exchanger for an air conditioner. The cross fin tube heat exchanger is configured by inserting a heat transfer tube 2 into a fin 1. In the past, heat transfer tubes have also been upgraded to achieve higher performance of heat exchangers.Spiral grooved tubes have been widely used as heat transfer tubes if spiral grooves are formed in the tubes. Was. Since such a spiral grooved pipe has a much higher heat transfer performance than a smooth pipe, when it is used for indoor and outdoor heat exchangers, high performance of an air conditioner is achieved. In recent years, in order to further improve the performance of this spiral grooved tube, a grooved tube having non-parallel grooves, for example, a cross grooved tube where the main groove and the sub groove intersect, and a fine sub groove provided at the tip of the inner fin A fine secondary grooved tube, a pine needle grooved tube having an inner groove formed in a pine needle shape, and the like have been developed. When such a grooved tube is used, the performance of the heat exchanger is improved and the size of the heat exchanger can be reduced, so that it is very effective for an indoor unit that has a high demand for compactness.

[0003] Conventionally, there has been an example in which different heat transfer tubes are used for a heat exchanger of an indoor unit and an outdoor unit of an air conditioner.
For example, in the literature (Paper Collection of 1997 Annual Meeting of the Japan Society of Refrigeration and Air Conditioning Society, p. 89), a grooved tube is used for the indoor heat exchanger, and a smooth tube is used for the outdoor heat exchanger.

[0004]

However, based on such a conventional idea, the above-mentioned recently considered heat-exchange-periphery grooved tube is simply used for indoor and outdoor heat exchangers.
It has been found that the performance as an air conditioner is rather deteriorated.

[0005] It is an object of the present invention to provide an air conditioner that improves the efficiency of the entire cycle in consideration of the heat transfer performance of the indoor and outdoor heat exchangers.

[0006]

An object of the present invention is to provide an air conditioner having an outdoor heat exchanger and an indoor heat exchanger each having a heat transfer tube through which a refrigerant flows, and these heat exchangers are connected by piping. In the above, the indoor heat exchanger includes a heat transfer tube having a plurality of grooves that are not parallel to the inner surface, and the outdoor heat exchanger includes a heat transfer tube that has a spiral groove formed on the inner surface. You.

In an air conditioner having an outdoor heat exchanger having a heat transfer tube through which a refrigerant flows and an indoor heat exchanger, and these heat exchangers are connected by piping, the indoor heat exchanger is an inner heat exchanger. Having a first portion including the top of the fin and a second portion including the root of the fin, the ridge line of the first portion having an uneven shape or a substantially wave shape. Achieved by shaping.

Further, the heat resistance of the heat transfer tube of the indoor heat exchanger when the refrigerant passes through the inside thereof is determined by the heat resistance of the heat transfer tube of the outdoor heat exchanger when the refrigerant passes through the inside thereof. This is achieved by making it larger than the resistance.

The helical grooved tube has a pressure loss of about 20 to 40% as compared with a smooth tube, while the heat transfer coefficient is more than doubled. At present, several internally grooved tubes having a higher heat transfer coefficient than the spiral grooved tube have been proposed. For example, a cross-grooved tube in which the sub-groove and the main groove on the inner surface intersect, or a fine 2 having fine irregularities at the tip of the inner fin
A secondary grooved tube or a pine needle grooved tube having an inner surface groove formed in a pine needle shape. However, these high-performance grooved tubes certainly have a higher heat transfer coefficient than the spiral grooved tube, but also increase the refrigerant pressure loss in the tube. Even if the heat transfer coefficient is improved, if the pressure loss in the pipe increases, the saturation temperature of the refrigerant changes, and the work of the compressor may increase in order to ensure the same heat exchange amount. Furthermore, when used as an outdoor evaporator, there is a problem that frost is easily formed in a region where the refrigerant temperature is low.

According to the present invention, in an air conditioner in which an outdoor unit and an indoor unit are connected, a spiral grooved tube having a small pressure loss is used for a heat transfer tube of the outdoor unit heat exchanger, and a high heat transfer coefficient is used for the indoor unit. By using a cross grooved pipe, a fine secondary grooved pipe, or a pine needle grooved pipe, a high-performance air conditioner can be provided even when the sizes of the indoor and outdoor units and the refrigerant flow ranges are different. Furthermore, an air conditioner that is resistant to frost can be provided because the refrigerant saturation temperature does not change much.

[0011]

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

FIG. 1 shows the structure of a grooved heat transfer tube according to a first embodiment of the present invention. FIG. 1 shows a cross-groove heat transfer tube 101 used for an indoor heat exchanger and a spiral grooved heat transfer tube 1 having a spiral groove formed on an inner surface used for an outdoor heat exchanger.
02 (for example, Literature, Transactions of the Japan Society of Mechanical Engineers, B45-38)
9, p118). These heat transfer tubes are refrigerant tubes through which the refrigerant flows, and the refrigerant exchanges heat with the outside of the heat transfer tubes. The cross-grooved pipe is different from the main groove 103 formed in a spiral shape with respect to the axis of the pipe as shown in the figure by changing the angle from the ridge direction of these grooves to another groove, for example, This is a grooved tube in which a sub-groove 104 is formed substantially parallel to the tube axis.

In the present invention, grooves (fins) are formed on the inner surface of the heat transfer tube used in the indoor heat exchanger in directions different from each other. Alternatively, the top of the groove (fin) is formed in an uneven shape or a substantially wavy shape. In a heat transfer tube having such grooves formed in different directions on the inner surface, irregularities are formed not only in the direction of the cross section of the tube but also in the direction of the ridge of the groove. Rather, a so-called three-dimensional mountain shape is formed. For this reason, the surface tension of the refrigerant liquid acting on the surface of the inner surface of the tube is a heat transfer tube having a single-shaped groove on the inner surface,
For example, it becomes larger than a spiral grooved tube. Since the thickness of the liquid film of the refrigerant liquid on the inner surface of the tube can be locally reduced, the heat resistance between the refrigerant liquid and the outside of the heat transfer tube can be reduced, and the heat transfer efficiency can be increased. Also, since the liquid film is formed in a region where the thickness of the liquid film is small, the position of the liquid film in the height direction is changed according to the unevenness, the area of the portion where the liquid film is thin and effectively acts on heat transfer can be increased. The heat transfer efficiency can be increased. Also,
Due to the three-dimensional mountain shape, the refrigerant liquid flowing inside the heat transfer tube is agitated, the turbulence of the refrigerant liquid is increased, turbulent heat transfer is promoted, and the heat transfer coefficient of the heat transfer tube can be increased.

As described above, a heat transfer tube having a small heat resistance, for example, a heat exchanger using a cross grooved tube as the indoor heat exchanger is replaced with a heat transfer tube having a higher heat resistance, for example, a spiral grooved tube at the outdoor side. The reason why the combination used as the heat exchanger is good will be described below. FIG. 5 is a perspective view of a cross fin tube heat exchanger widely used in air conditioners at present. In the air conditioner of the present invention, the heat transfer tube shown in FIG. 1 is inserted into a fin as shown in FIG. 5 and configured as a heat exchanger. In this figure, the fins are inserted into multiple heat transfer tubes,
The same applies to independent fins having different fins for each heat transfer tube. Early cross fin tube heat exchangers used smooth tubes as heat transfer tubes. When spiral grooved tubes were developed, the spiral grooved tubes became widely used because of their higher heat transfer coefficient than smooth tubes.

The coefficient of performance indicating the heating performance at that time will be described with reference to FIG. . FIG. 6 is a graph showing the heating COP ratio in each case where a plurality of types of heat transfer tubes are used in combination for the indoor heat exchanger and the outdoor heat exchanger. It is obvious that the use of the grooved tube in the indoor unit alone can improve the performance, but the use of the grooved tube in both the indoor unit and the outdoor unit can further improve the performance. For example, when the spiral grooved pipe is used for the indoor and outdoor heat exchangers, the heating C is compared with the case where the spiral grooved pipe is used only for the indoor side and the smooth pipe is used for the outdoor side.
FIG. 6 shows that the OP ratio is high. In recent years, the cross-grooved tube, the fine secondary grooved tube, or the Matsuba grooved tube, which has a smaller heat resistance than the spiral grooved tube and has a higher heat transfer coefficient (for example, the Japan Refrigeration Association Academic Lecture Meeting, 199
6, p49) have been developed.

The use of these high-performance grooved pipes for heating in an indoor unit further improves the heating performance, but when applied to an outdoor unit, the performance may be deteriorated. For example, when using cross grooved tubes for indoor and outdoor heat exchangers,
FIG. 6 shows that the heating COP ratio is smaller than when a cross grooved pipe is used only on the indoor side and a spiral grooved pipe is used on the outdoor side. That is, from the smooth pipe to the spiral grooved pipe, it was possible to improve the performance of the entire air conditioner (higher heating COP) by increasing the heat transfer coefficient of the heat transfer pipe.
However, as the heat transfer performance of the heat transfer tubes has been improved by devising the groove shape, there have been cases where higher performance of grooved tubes does not lead to overall higher performance of air conditioners, FIG. 6 shows this.

The above-mentioned phenomena are caused by the characteristics of these high performance grooved pipes and the differences in the use conditions and forms of the indoor unit and the outdoor unit of the air conditioner. FIG. 7 is a schematic diagram showing a combination of an indoor unit and an outdoor unit of a room air conditioner. In general, indoor units and outdoor units have a higher demand for compactness on the indoor side, so that the indoor units are relatively small and the outdoor units are relatively large. Also, the temperature difference between the air and the refrigerant is generally smaller on the outdoor side. Further, due to the problem of frost, the outdoor heat exchanger has a large fin pitch and fin depth and low heat transfer performance. For these reasons, outdoor heat exchangers are generally larger than indoor heat exchangers. The indoor heat exchanger is required to be smaller than the outdoor heat exchanger, so it is necessary to increase the efficiency of heat exchange. It is effective to use a tube. On the other hand, since the outdoor heat exchanger is large, the length of the heat transfer tube is long, and the pressure loss of the refrigerant increases.

When a heat exchanger having a large refrigerant pressure loss is used in the refrigeration cycle shown in FIG. 8, the refrigeration cycle changes from a solid line 1-2-3-4 to a dotted line 1'-2'-3'-4 '. The compressor work increases and the efficiency of the air conditioner decreases. In particular, a pressure change is large in an evaporator having a small gas density and a large gas flow rate. Corresponding to this change, the condenser inlet pressure increases and the evaporator outlet pressure decreases, thus increasing compressor work. The increase in the pressure loss causes a problem in that the efficiency of the air conditioner decreases.

Since the cross-groove heat transfer tube promotes turbulent flow of the refrigerant liquid due to its groove shape and locally reduces the thickness of the liquid film to reduce the thermal resistance, the heat transfer tube with the spiral groove has a spiral groove. Naturally, the heat transfer coefficient is improved as compared with the tube, but the pressure loss of the liquid refrigerant is increased in these portions, and the performance is rather deteriorated. Therefore, a small indoor heat exchanger has a cross-grooved tube with low thermal resistance and high heat transfer efficiency, and performance degradation due to refrigerant pressure loss in the tube is problematic. It is effective to use a grooved tube having a small directional resistance and a small pressure loss, for example, a spiral grooved tube.

Further, in the outdoor unit during the heating operation, if the refrigerant saturation pressure changes in the refrigerant flow direction, frost is formed at a low refrigerant saturation temperature as shown in FIG. 9 and the fins are clogged to impede the air flow. The performance of the exchanger will be reduced. However, the wind is flowing in the direction perpendicular to the paper of FIG. Once frost starts to be formed in any region of the heat exchanger, the evaporation temperature of the refrigerant decreases in order to secure the amount of heat to be exchanged, causing a vicious cycle in which frost is further advanced. In order to prevent performance deterioration due to frost formation, it is important not to create a region where frost easily forms, that is, not to create a region where the refrigerant evaporation temperature is low. For this purpose, it is desirable to make the refrigerant saturation pressure in the heat exchanger substantially constant, and thus it is effective to use a heat transfer tube having a small pressure loss for the outdoor heat exchanger. Therefore,
A heat exchanger using a heat transfer tube with a small thermal resistance like a cross grooved tube on the indoor side, and a heat transfer tube with a large heat resistance but smaller pressure loss like a spiral grooved tube on the outdoor side, for example. Combination with a heat exchanger that uses frost prevents frost formation and reduces performance degradation due to frost formation.

Furthermore, as shown in FIG. 10, in a multi-air conditioner in which a plurality of indoor units 1001 and outdoor units 1002 are connected, a heat exchanger is used because the refrigerant flow rate of the outdoor units is relatively larger than that of the indoor units. It becomes large. Correspondingly, the flow path of the heat transfer tube becomes longer, and performance deterioration due to refrigerant pressure loss becomes more problematic. Therefore, in this case as well, a heat exchanger using a heat transfer tube having a small thermal resistance such as a cross grooved tube on the indoor side and a pressure loss on the outdoor side even if the thermal resistance is large, such as a spiral grooved tube, are used. Combination with a heat exchanger using a heat transfer tube smaller than the above is effective.

When a non-azeotropic refrigerant mixture is used, the heat transfer coefficient is greatly reduced in a region where the refrigerant mass velocity is small as shown in FIG. Accordingly, it is effective to use the refrigerant in a refrigerant mass velocity region larger than that of a single refrigerant or a pseudo-azeotropic mixed refrigerant in order to prevent any deterioration in performance. However, in the case of an outdoor unit, it must be large as described above,
Further, the pressure loss of the refrigerant becomes larger than the increase of the heat transfer coefficient due to frosting, and if the mass velocity of the refrigerant is increased unnecessarily, the performance of the non-azeotropic mixed refrigerant is reduced. Therefore, even in the case of a non-azeotropic refrigerant mixture, it is effective to use a heat transfer tube having a large heat resistance and a small pressure loss, such as a spiral grooved tube, for the outdoor unit.

If the outside air temperature becomes high during the cooling operation, the condensation pressure of the outdoor unit rises, and the pressure resistance of the heat transfer tube becomes a problem. Therefore, it is desirable that the heat transfer tube used in the outdoor heat exchanger be thick. In this case, since the material cost of the outdoor heat exchanger increases, the spiral grooved tube which is easy to process is reduced in cost and is effective.

Incidentally, similar means for obtaining the above-described effects include increasing the number of passes of the outdoor unit and increasing the pipe diameter. By increasing the number of passes,
This is because the refrigerant flow rate per path is reduced, so that the refrigerant pressure loss can be reduced, and even if the pipe diameter is increased, the flow rate per cross-sectional area is reduced, so that the refrigerant pressure loss can be reduced. However, an increase in the number of passes leads to an increase in the cost of manufacturing and assembling the piping, and an increase in the pipe diameter leads to an increase in the amount of filled refrigerant and the weight of the heat exchanger, or a decrease in the air-side heat transfer performance. It is desirable to avoid as much as possible.

The performance of each grooved tube and its positioning are summarized in FIG. FIG. 12 shows a line that gives an evaporation capacity equivalent to that of the existing spiral grooved tube when the indoor and outdoor heat exchangers are used as evaporators.

The way to read this figure is as follows. For example, even if the heat transfer coefficient increases, if the pressure loss increases so as to be on this line, the air conditioning function will be the same. In other words, a heat transfer tube on this line gives the same performance as the current spiral grooved tube as an evaporator, and a heat transfer tube in the hatched area at the lower right of this line uses the current spiral grooved tube. The performance is improved compared to the evaporator that was used.
This boundary line is not the same line between the indoor heat exchanger and the outdoor heat exchanger. This is because the performance required for the heat transfer coefficient in the pipe and the refrigerant pressure loss is different between the indoor unit and the outdoor unit as described above. Since the smooth tube is above both lines, it can be seen that the performance is lower than the current spiral grooved tube. On the other hand, when a grooved pipe having higher performance than the current spiral grooved pipe is used, for example, a higher performance spiral grooved pipe has improved performance when used in both indoor and outdoor units.

However, a grooved tube having a high heat transfer coefficient but a large pressure loss, such as a cross-grooved tube, is effective when used in an indoor unit, but deteriorates in performance when used in an outdoor unit. As described above, since the indoor heat exchanger and the outdoor heat exchanger have different use conditions and forms, the optimum grooved pipe also differs. A heat exchanger using a heat transfer tube having a small thermal resistance on the indoor side, for example, a heat exchanger using a cross grooved tube, and a heat exchanger using a heat transfer tube having a large thermal resistance but a smaller pressure loss on the outdoor side, for example, using a heat transfer tube with a spiral groove. By using the exchanger, high performance can be exhibited.

As an example of an air conditioner using different heat transfer tubes in each heat exchanger, as disclosed in Japanese Patent Application Laid-Open No. 5-340630, a primary heat exchanger for making ice in a heat storage tank is used. There is a technique using a grooved pipe as a secondary heat exchanger for transporting the stored heat of a smooth pipe into a room. In this technique, since ice is made in the primary heat exchanger, ice grows around the heat transfer tube, and the thermal resistance of the ice becomes a controlling factor of the heat exchange rate of the entire apparatus. In this case as well, the use of a grooved tube will provide higher performance, but since the heat resistance inside the tube does not affect the heat resistance of the entire primary heat exchanger, it is meaningless to improve the performance inside the tube unnecessarily. Absent. For this reason, a smooth tube is used for the primary heat exchanger.

The effect of the present invention can be obtained not only by making the refrigerant pipe of the indoor heat exchanger a cross grooved pipe, but by reducing the heat resistance of the indoor heat exchanger and the refrigerant pipe by the outdoor heat exchanger and the refrigerant. It is obtained by reducing the thermal resistance in the tube. FIG. 2 shows a cross grooved tube 201 used for an indoor heat exchanger of an air conditioner according to the present invention and a spiral grooved tube used for an outdoor heat exchanger as a modification of the embodiment shown in FIG. It is sectional drawing which shows the tube inner surface of 202. This cross-grooved tube has a first spiral main groove 203 and a sub-groove 204 engraved in a direction different from the spiral angle and sign of the main groove. The other description is the same as that of the above embodiment.

As shown in FIG. 3, as a modification of the above-described embodiment, a fine secondary grooved tube 301 provided with fine irregularities 303 at the tip of an inner fin may be used as a heat exchanger tube for an indoor heat exchanger. good. FIG. 3 is a cross-sectional view showing a fine secondary grooved tube 301 used in the indoor heat exchanger of the air conditioner according to the present invention and a spiral grooved tube 302 used in the outdoor heat exchanger. In the fine secondary grooved tube, the fine irregularities 303 at the tip of the inner fin effectively act on the surface tension effect, and the heat transfer coefficient is greatly improved. Regarding the unevenness of the groove, the action of this embodiment does not change not only in the depth direction of the groove but also when the height of the groove peak (convex portion) or the ridge of the groove peak is undulated. The other description is the same as in the above embodiment.

As shown in FIG. 4, as a modification of the above-described embodiment, a pine needle grooved tube 401 whose inner surface groove is carved into a pine needle shape may be used as a heat exchanger tube for an indoor heat exchanger. FIG.
FIG. 3 is a cross-sectional view showing the inner surface of a pine grooved tube 401 used for an indoor heat exchanger of an air conditioner according to the present invention and a spiral grooved tube 402 used for an outdoor heat exchanger.

In such a heat transfer tube, when the inner surface is developed, grooves formed in a pine needle shape are combined and formed. In the portion where the pine needle-shaped grooves gather, the refrigerant liquid is collected along the grooves, and the liquid film thickness increases. On the other hand, the liquid film thickness becomes thinner at the portion where the pine needle-shaped grooves are separated, so that regions having different liquid film thickness are formed on the inner surface of the tube. In the region where the liquid film thickness is reduced, the thermal resistance between the refrigerant liquid and the outside of the heat transfer tube can be reduced, and the thermal resistance can be reduced. Further, in the soot portion of the pine needle-shaped grooves, turbulence increases due to collision of the refrigerant liquid, and turbulent heat transfer can be promoted, so that the heat transfer coefficient can be increased. The other description is the same as that of the above embodiment.

[0033]

As described above, according to the present invention, it is possible to provide an air conditioner that improves the efficiency of the entire cycle in consideration of the heat transfer performance of the indoor and outdoor heat exchangers.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an inner surface of a cross grooved tube used in an indoor heat exchanger of an air conditioner according to the present invention and a spiral grooved tube used in an outdoor heat exchanger.

FIG. 2 is a cross-sectional view showing an inner surface of a cross grooved tube used for an indoor heat exchanger of an air conditioner according to the present invention and a spiral grooved tube used for an outdoor heat exchanger.

FIG. 3 is a sectional view showing an inner surface of a fine secondary grooved tube used in an indoor heat exchanger of an air conditioner according to the present invention and a spiral grooved tube used in an outdoor heat exchanger.

FIG. 4 is a cross-sectional view showing an inner surface of a pine grooved tube used in an indoor heat exchanger of an air conditioner according to the present invention and a spiral grooved tube used in an outdoor heat exchanger.

FIG. 5 is a perspective sectional view of a heat exchanger using a cross fin tube.

FIG. 6 is a graph showing a heating COP ratio in each case where a plurality of types of heat transfer tubes are used in combination for an indoor heat exchanger and an outdoor heat exchanger.

FIG. 7 is a schematic diagram showing a combination of an indoor unit and an outdoor unit of a room air conditioner.

FIG. 8 is a schematic diagram of a refrigeration cycle.

FIG. 9 is a schematic view of a frosted heat exchanger.

FIG. 10 is a schematic diagram of an air conditioner in which more indoor units are connected to the outdoor units than the outdoor units.

FIG. 11 is a graph showing heat transfer tube performance when a non-azeotropic mixed refrigerant is used.

FIG. 12 is a diagram showing the performance of various heat transfer tubes and their positioning.

[Explanation of symbols]

1 ... Fins. 2 ... heat transfer tubes. 101 Cross-grooved tube for indoor heat exchanger according to the first embodiment of the present invention. 102 Spiral grooved tube for outdoor heat exchanger according to the first embodiment of the present invention. 201 Cross-grooved tube for indoor heat exchanger according to the second embodiment of the present invention. 202 ... Spiral grooved tube for outdoor heat exchanger according to the second embodiment of the present invention. 301... Fine secondary grooved tube for indoor heat exchanger according to the third embodiment of the present invention. 302. A spiral grooved tube for an outdoor heat exchanger according to a third embodiment of the present invention. 401 ... Matsuba grooved tube for indoor heat exchanger according to the fourth embodiment of the present invention. 402 A spiral grooved tube for an outdoor heat exchanger according to a fourth embodiment of the present invention. 701 ... air conditioner indoor unit. 702 ... air conditioner outdoor unit. 703: Indoor heat exchanger. 704: outdoor heat exchanger. 705: refrigerant pipe. 801 Compressor. 802: A condenser. 803: Evaporator. 804 An expansion valve. 901: frost. 902 ... refrigerant flow direction. 1001 ... air conditioner indoor unit. 1002 ... Air conditioner outdoor unit. 1003 ... indoor heat exchanger. 1004 ... outdoor heat exchanger. 1005 ... refrigerant pipe.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masaaki Ito 502 Kandate-cho, Tsuchiura-shi, Ibaraki Pref. Machinery Research Laboratory, Hitachi, Ltd. Inside the Machinery Research Laboratory (72) Inventor Hisahei Ishibane 390 Muramatsu, Shimizu-shi, Shizuoka Prefecture Air Conditioning Systems Division, Hitachi, Ltd.

Claims (4)

[Claims] An air conditioner having a heat cycle in which an outdoor heat exchanger having a heat transfer tube through which a refrigerant flows, a compressor, an indoor heat exchanger, and an expansion valve are connected in this order.
An air conditioner in which an indoor heat exchanger includes a heat transfer tube having a plurality of non-parallel grooves formed on an inner surface thereof, and an outdoor heat exchanger includes a heat transfer tube having a spiral groove formed on an inner surface thereof. 2. An air conditioner having a heat cycle in which an outdoor heat exchanger having a heat transfer tube through which a refrigerant flows, a compressor, an indoor heat exchanger, and an expansion valve are connected in this order.
The indoor heat exchanger has fins formed on the inner surface,
The air conditioner includes a first portion including a top portion of the fin and a second portion including a root of the fin, and a ridge of the first portion has an uneven shape or a substantially wavy shape. 3. A heat cycle in which an outdoor heat exchanger having a heat transfer tube through which a refrigerant flows, a compressor, an indoor heat exchanger, and an expansion valve are connected in this order, and the outdoor heat exchanger has an inner surface. In an air conditioner having a heat transfer tube formed with a spiral groove, the indoor heat exchanger has a heat resistance when the refrigerant passes through the inside thereof, and the heat transfer tube of the outdoor heat exchanger has An air conditioner equipped with a heat transfer tube having a thermal resistance greater than the thermal resistance of the refrigerant when passing through the interior 4. The air conditioner according to claim 1, wherein a length of the heat transfer tube forming the indoor heat exchanger is longer than a length of the heat transfer tube forming the outdoor heat exchanger. Short air conditioner.