JP5627635B2 - Air conditioner - Google Patents

Description

  The present invention relates to an air conditioner using a heat exchanger having a heat transfer tube.

  Conventionally, a fin tube type that is composed of fins that are arranged at regular intervals and through which gas (air) flows and heat transfer tubes that have grooves on the inner surface of the tubes and that are inserted at right angles to the fins and into which refrigerant flows. 2. Description of the Related Art A heat pump type air conditioner using such a heat exchanger is known.

  In general, an air conditioner is an evaporator that evaporates refrigerant and cools air, water, and the like by heat of vaporization at that time, and a compressor that compresses refrigerant discharged from the evaporator and supplies the refrigerant to a condenser at a high temperature And a condenser that heats air and water by the heat of the refrigerant, an expansion valve that expands the refrigerant discharged from the condenser and supplies the refrigerant to the evaporator at a low temperature, and switches the flow direction of the refrigerant in the refrigeration cycle Thus, a four-way valve that switches between heating operation and cooling operation is provided. And a heat exchanger tube is built in a condenser and an evaporator, and the refrigerant containing refrigerating machine oil is poured in the inside.

  In recent years, to improve the performance of heat exchangers, indoor heat exchangers use flat tubes with a flat cross section, and outdoor heat exchangers use heat transfer tubes with a spiral groove shape on the inner surface of a circular tube. It has been proposed (see Patent Document 1). In addition, an indoor heat exchanger that uses a cross groove shape that is not parallel to the inner surface of the circular tube and an outdoor heat exchanger that uses a heat transfer tube that uses a spiral groove shape on the inner surface of the circular tube has been proposed (Patent Literature). 2). The performance of the air conditioner can be improved by using heat transfer tubes having different types of inner surface groove shapes for the heat exchanger mounted on the indoor unit and the heat exchanger mounted on the outdoor unit.

JP-A-8-247576 (FIG. 2) Japanese Patent Laid-Open No. 11-264630 (FIG. 1)

By the way, in the air conditioner as described above, the pressure loss in the pipe of the outdoor heat exchanger during the heating operation is reduced by making the number of passes of the outdoor heat exchanger larger than the number of passes of the indoor heat exchanger. I am doing so. Further, it is conceivable to reduce the diameter of the heat transfer tube for the purpose of improving the performance of the heat exchanger.
However, by reducing the diameter of the heat transfer tube, the heat transfer coefficient in the tube increases, but the pressure loss increases. Therefore, it is necessary to optimize them. In addition, the small-diameter heat transfer tube is advantageous in terms of heat transfer performance, but has a problem that the manufacturing cost of the heat transfer tube increases. In recent years, improvement in efficiency during heating operation that greatly contributes to period energy consumption efficiency (APF) has been desired. In addition, it is desired to improve the low temperature heating performance in cold regions.

  In view of the above points, the present invention provides an air conditioner that can increase the heat exchange capacity of an indoor heat exchanger without increasing the pressure loss in the pipe of the outdoor heat exchanger.

An air conditioner according to the present invention is a refrigerant in which a compressor, an outdoor heat exchanger mounted on an outdoor unit, an expansion unit, and an indoor heat exchanger mounted on the indoor unit are sequentially connected by piping. The outdoor heat exchanger and the indoor heat exchanger are arranged at a predetermined interval and a plurality of fins through which airflow flows, and the refrigerant is passed through the fins and flows through the inside. A heat pipe, and the heat exchanger tube of the outdoor heat exchanger is a flat tube that has a flat cross section and is arranged so that the long direction of the flat shape faces the flow direction of the airflow, The flat long length is configured to be 14 mm or more and 22 mm or less, and the flow rate of the refrigerant flowing through the heat transfer tube of the indoor heat exchanger and the flow rate of the refrigerant flowing through the heat transfer tube of the outdoor heat exchanger ratio is greater than 2.3, it is configured to be less than 11.6 It has been.

  The present invention can increase the pressure on the low pressure side without increasing the pressure loss in the pipe of the outdoor heat exchanger, and can improve the efficiency of the air conditioner.

It is a figure which shows the structure of the air conditioner which concerns on Embodiment 1 of this invention. It is a figure which shows the outdoor side heat exchanger which concerns on Embodiment 1 of this invention. It is a figure which shows the influence of the elongate flat tube of the outdoor heat exchanger which concerns on Embodiment 1 of this invention. It is a figure which shows ratio of the refrigerant | coolant flow rate of the indoor side heat exchanger which concerns on Embodiment 1 of this invention, and the refrigerant | coolant flow rate of an outdoor side heat exchanger. It is a figure which shows the structure of the air conditioner which concerns on Embodiment 2 of this invention. It is a figure which shows the indoor side heat exchanger which concerns on Embodiment 3 of this invention.

Embodiment 1 FIG.
1 is a diagram showing a configuration of an air conditioner according to Embodiment 1 of the present invention.
As shown in FIG. 1, an air conditioner is mounted on a compressor 5, a four-way valve 8, an outdoor heat exchanger 3 mounted on an outdoor unit, an expansion valve 7 that is an expansion means, and an indoor unit. The indoor-side heat exchanger 2 is connected with a refrigerant pipe in order, and has a refrigeration cycle (refrigerant circuit) for circulating the refrigerant.
The four-way valve 8 switches between the heating operation and the cooling operation by switching the direction in which the refrigerant flows in the refrigeration cycle. In addition, when it is set as the air conditioner only for cooling or heating, the four-way valve 8 may be omitted. The outdoor heat exchanger 3 functions as a condenser that heats the air or the like with the heat of the refrigerant during the cooling operation, and functions as an evaporator that evaporates the refrigerant and cools the air or the like with the heat of vaporization during the heating operation. To do. The indoor heat exchanger 2 functions as a refrigerant evaporator during the cooling operation, and functions as a refrigerant condenser during the heating operation. The compressor 5 compresses the refrigerant discharged from the evaporator and supplies it to the condenser at a high temperature. The expansion valve 7 expands the refrigerant discharged from the condenser, and supplies it to the evaporator at a low temperature. As the refrigerant, any one of HC single refrigerant, a mixed refrigerant containing HC, R32, R410A, R407C, and carbon dioxide is used. If the heat transfer tubes of the indoor heat exchanger 2 and the outdoor heat exchanger 3 are made thinner, the pressure loss inside the heat transfer tubes will increase. Using either HC single refrigerant with low pressure loss in the pipe, or mixed refrigerant containing HC, R32, R410A, R407C, or carbon dioxide can increase the heat transfer performance of the evaporation pipe without increasing the pressure loss. Therefore, a highly efficient heat exchanger can be provided.

  The outdoor heat exchanger 3 and the indoor heat exchanger 2 are fin-tube heat exchangers widely used as evaporators and condensers such as refrigeration apparatuses and air conditioners. The outdoor heat exchanger 3 and the indoor heat exchanger 2 are composed of a plurality of fins and heat transfer tubes. Heat transfer tubes are provided so as to penetrate through holes provided in each fin with respect to a plurality of fins arranged at predetermined intervals. The heat transfer tube becomes a part of the refrigerant circuit in the refrigeration cycle, and the refrigerant flows inside the tube. By transferring the heat of the refrigerant flowing inside the heat transfer tube and the air flowing outside through the fins, the heat transfer area serving as a contact surface with the air is expanded, and heat exchange between the refrigerant and the air can be performed efficiently.

Next, details of the configuration of the outdoor heat exchanger 3 will be described with reference to FIG.
FIG. 2 is a diagram showing an outdoor heat exchanger according to Embodiment 1 of the present invention. In addition, FIG. 2 has shown a part of cross section which looked at the outdoor side heat exchanger 3 from the side surface side.
In FIG. 2, the fins 10 have, for example, a plate shape, and a plurality of fins 10 are stacked at a predetermined interval, and fluid flows between them.
The heat transfer tube of the outdoor heat exchanger 3 uses a flat tube 20 having a flat cross section and a flat long length L_out of 14 mm or more and 22 mm or less.
The flat tubes 20 are arranged in a plurality with a flat major axis direction in the fluid flow direction (left-right direction on the paper surface) and with a gap in the flat minor axis direction (up-down direction on the paper surface). Headers are respectively connected to both ends of the flat tube 20, and the refrigerant is distributed to the plurality of flat tubes 20. A plurality of refrigerant channels 21 are formed inside the flat tube 20.
In addition, although the example shown in FIG. 2 shows the case where two rows of flat tubes 20 are provided, the present invention is not limited to this, and one row may be provided, or three or more rows may be provided.

Here, the frosting strength and the bending strength of the outdoor heat exchanger 3 will be described.
FIG. 3 is a diagram showing the influence of the length of the flat tube of the outdoor heat exchanger according to Embodiment 1 of the present invention. In FIG. 3, the solid line indicates the bending strength of the heat exchanger, and the dotted line indicates the frosting strength of the heat exchanger.
When the outdoor heat exchanger 3 functions as an evaporator, a low-temperature refrigerant (for example, 0 ° C. or less) flows through the flat tube 20. At this time, moisture (water vapor) in the air passing between the fins 10 and around the flat tube 20 is condensed and attached (frosted) as frost. Frost is likely to form around the flat tube 20 through which a low-temperature refrigerant flows, and when the amount of frost increases, the flow of air passing between the fins 10 is hindered, increasing the ventilation resistance and reducing the frost resistance. .
As shown in FIG. 3, when the length of the flat tube 20 of the outdoor heat exchanger 3 is shortened, the frosting resistance is reduced. This is because, when the long length of the flat tube 20 is short, the frosting range is also narrowed, and the ventilation resistance accompanying the frosting is increased. Moreover, since the width | variety (length of the distribution direction of a fluid) of the fin 10 will also become short if the elongate length of the flat tube 20 is short, since the range which forms frost becomes narrow and the ventilation resistance accompanying frost formation increases. It is.

  On the other hand, when the long length of the flat tube 20 of the outdoor heat exchanger 3 is increased, the frosting resistance increases, but the bending resistance of the heat exchanger decreases. This is because if the length of the flat tube 20 is long, the contact area between the flat tube 20 and the fins 10 increases, and the fins are likely to be peeled off by bending or the like. Further, when the long length of the flat tube 20 is long, the width of the fin 10 (the length in the fluid flow direction) is also long, so that the fin 10 is likely to be deformed.

  From the above, the length of the flat tube 20 in the present embodiment is set to 14 mm or more and 22 mm or less as a range in which the frost proof strength and bending strength of the outdoor heat exchanger 3 are not significantly lowered. That is, the length of the flat tube 20 is set to 14 mm or more and 22 mm or less. When the length of the flat tube 20 of the outdoor heat exchanger 3 is set to 14 mm or less, the frosting resistance is reduced and the air conditioning is reduced. This is because the decrease in efficiency of the machine becomes remarkable. Further, when the long length of the flat tube 20 of the outdoor heat exchanger 3 is set to 22 mm or more, the bending strength of the heat exchanger is significantly lowered.

  By setting the long length of the flat tube 20 of the outdoor heat exchanger 3 as described above, the frosting resistance and bending resistance of the outdoor heat exchanger 3 can be further improved, and high efficiency. The outdoor heat exchanger 3 can be obtained.

Next, the ratio (Gr_indoor) between the flow rate of refrigerant flowing through the heat transfer tube of the indoor heat exchanger 2 (refrigerant flow rate; Gr_indoor) and the flow rate of refrigerant flowing through the heat transfer tube of the outdoor heat exchanger 3 (refrigerant flow rate; Gr_outdoor). / Gr_outdoor) will be described.
FIG. 4 is a diagram showing a ratio between the refrigerant flow rate of the indoor heat exchanger and the refrigerant flow rate of the outdoor heat exchanger according to Embodiment 1 of the present invention.
As shown in FIG. 4, when the ratio between the refrigerant flow rate of the indoor heat exchanger 2 and the refrigerant flow rate of the outdoor heat exchanger 3 increases, the outdoor performance and the indoor performance deteriorate, and the efficiency of the air conditioner decreases. Become prominent. On the other hand, when the ratio of the refrigerant flow rate of the indoor heat exchanger 2 and the refrigerant flow rate of the outdoor heat exchanger 3 is reduced, the pressure loss in the pipe of the outdoor heat exchanger is increased and the efficiency of the air conditioner is significantly reduced. Become.

As described above, in the present embodiment, the ratio (Gr_indoor / Gr_outdoor) between the refrigerant flow rate of the indoor heat exchanger 2 and the refrigerant flow rate of the outdoor heat exchanger 3 is larger than 2.3. The cross-sectional area and the number of passes of the heat transfer tubes of the outdoor heat exchanger 3 and the indoor heat exchanger 2 are set so as to be smaller than .6.
This is because when the ratio of the refrigerant flow rate of the indoor heat exchanger 2 to the refrigerant flow rate of the outdoor heat exchanger 3 (Gr_indoor / Gr_outdoor) is 2.3 or less, the outdoor performance and the indoor performance are reduced, and the air conditioner This is because the reduction in efficiency of the above becomes remarkable. Moreover, if the ratio (Gr_indoor / Gr_outdoor) of the refrigerant flow rate of the indoor heat exchanger 2 and the refrigerant flow rate of the outdoor heat exchanger 3 is 11.6 or more, the pressure loss in the pipe of the outdoor heat exchanger increases, This is because the reduction in the efficiency of the harmony machine becomes significant.

  By setting the ratio (Gr_indoor / Gr_outdoor) between the refrigerant flow rate of the indoor heat exchanger 2 and the refrigerant flow rate of the outdoor heat exchanger 3 as described above, the pressure loss in the pipe of the outdoor heat exchanger 3 is increased. Therefore, the heat exchange capability of the indoor heat exchanger 2 can be increased, and a highly efficient outdoor heat exchanger 3 can be obtained.

Thereby, a high-efficiency air conditioner can be obtained in any operation of cooling and heating.
The heat exchanger of the present embodiment is used as an evaporator or a condenser in a refrigeration cycle in which a compressor, a condenser, a throttle device, and an evaporator are sequentially connected by piping and a refrigerant is used as a working fluid. This contributes to improvement of the coefficient (COP). In addition, the efficiency of heat exchange between the refrigerant and air is improved. Therefore, improvement of period energy consumption efficiency (APF) can be expected.

  In order to reduce the pressure loss of the heat exchanger, it is conceivable to increase the number of passes. However, an increase in the number of passes increases the manufacturing cost of the heat exchanger. Therefore, a greater effect can be expected when using a flat tube having a long length of 14 mm or more and 22 mm or less as the flat tube 20 of the outdoor heat exchanger 3.

Embodiment 2. FIG.
FIG. 5 is a diagram showing a configuration of an air conditioner according to Embodiment 2 of the present invention.
As shown in FIG. 5, the second embodiment includes a plurality of indoor heat exchangers 2. Here, an example provided with three indoor side heat exchangers 2-1 to 2-3 will be described.
Other configurations are the same as those of the first embodiment, and the same reference numerals are given to the same portions.

In the present embodiment, the ratio (Gr0_indoor) of the sum of refrigerant flow rates of the plurality of indoor heat exchangers 2-1 to 2-3 to the refrigerant flow rate (Gr_outdoor) of the outdoor heat exchanger 3 ( The cross-sectional area and the number of passes of the heat transfer tubes of the outdoor side heat exchanger 3 and the indoor side heat exchanger 2 are set so that Gr0_indoor / Gr_outdoor) is larger than 2.3 and smaller than 11.6.

Here, a value (Gr0_indoor) obtained by adding the refrigerant flow rates of the plurality of indoor heat exchangers 2-1 to 2-3 is as follows.
Gr0_indoor = Σ (Grn_indoor) (n = 1, 2,... Number)
Grn_indoor is the refrigerant flow rate of the nth indoor heat exchanger 2.
Further, when the refrigerant flow speeds of the plurality of indoor heat exchangers 2 are the same, Gr0_indoor = Gr_indoor × the number of indoor heat exchangers 2 is obtained.

  Even when a plurality of indoor heat exchangers 2 are provided as described above, as in the first embodiment, the pressure loss in the indoor heat exchanger 2 is increased without increasing the pressure loss in the outdoor heat exchanger 3. The heat exchange capability can be increased, and a highly efficient outdoor heat exchanger 3 can be obtained.

In addition, it is good also as a structure provided with two or more outdoor heat exchangers 3. FIG. In this case, the ratio (Gr0_indoor / Gr0_outdoor) of the value (Gr0_indoor) obtained by adding the refrigerant flow rates of the plurality of indoor heat exchangers 2 to the refrigerant flow rate (Gr0_outdoor) of the plurality of outdoor heat exchangers 3 is 2 The cross-sectional area and the number of passes of the heat transfer tubes of the outdoor heat exchanger 3 and the indoor heat exchanger 2 are set so as to be larger than .3 and smaller than 11.6. The same effect can be obtained by such a configuration.

Embodiment 3 FIG.
FIG. 6 is a diagram showing an indoor heat exchanger according to Embodiment 3 of the present invention. In addition, FIG. 6 has shown a part of cross section which looked at the indoor side heat exchanger 2 from the side surface side.
In FIG. 6, the fins 10 have, for example, a plate shape, a plurality of fins 10 are stacked at a predetermined interval, and a fluid flows between them.
The heat transfer tube of the indoor side heat exchanger 2 uses a circular tube 30 having a circular cross section.
A plurality of circular tubes 30 are arranged at intervals in a direction (vertical direction in the drawing) perpendicular to the airflow direction. Headers are connected to both ends of the circular pipe 30, and the refrigerant is distributed to the plurality of circular pipes 30. In addition, although the example shown in FIG. 6 shows the case where the circular tubes 30 are provided in three rows, the present invention is not limited to this, and an arbitrary row may be provided.
Other configurations are the same as those in the first or second embodiment, and the flat tube 20 is used as the heat transfer tube of the outdoor heat exchanger 3.

The diameter D_in (inner diameter) of the circular tube 30 of the indoor heat exchanger 2 is 4 mm or more and 6.35 mm or less.
This is because if the diameter of the circular tube 30 of the indoor heat exchanger 2 is 4 mm or less, the pressure loss in the indoor tube increases and the efficiency of the air conditioner decreases significantly. Further, if the diameter of the circular tube 30 of the indoor heat exchanger 2 is set to 6.35 mm or more, the refrigerant flow rate in the indoor tube becomes slow, and the efficiency of the air conditioner decreases significantly.

  By setting the diameter of the circular tube 30 of the indoor heat exchanger 2 as described above, the heat transfer performance of the indoor heat exchanger 2 can be further improved, and the highly efficient outdoor heat exchanger 3 can be obtained. Can be obtained.

Moreover, the hydraulic diameter of the flat tube 20 of the outdoor heat exchanger 3 is 2 mm or more and 4 mm or less.
This is because when the hydraulic diameter of the flat tube 20 of the outdoor heat exchanger 3 is 2 mm or less, the pressure loss inside the outdoor tube increases and the efficiency of the air conditioner decreases significantly. Further, when the hydraulic diameter of the flat tube 20 of the outdoor heat exchanger 3 is 4 mm or more, the refrigerant flow rate in the outdoor tube becomes slow, and the efficiency of the air conditioner is significantly reduced.
The hydraulic diameter of the flat tube 20 is the diameter of a circular tube equivalent to the cross section of the plurality of refrigerant channels 21 of the flat tube 20.

  By setting the hydraulic diameter of the flat tube 20 of the outdoor heat exchanger 3 as described above, the heat transfer performance of the indoor heat exchanger 2 can be further improved, and the highly efficient outdoor heat exchanger 3 can be improved. Can be obtained.

Embodiment 4 FIG.
The heat transfer tube of the indoor side heat exchanger 2 in the fourth embodiment uses a flat tube 20 having a flat cross section.
Other configurations are the same as those in the first or second embodiment, and the flat tube 20 is used as the heat transfer tube of the outdoor heat exchanger 3.

The hydraulic diameter of the flat tube 20 of the indoor heat exchanger 2 is 0.5 mm or more and less than 2 mm, and the hydraulic diameter of the flat tube 20 of the outdoor heat exchanger 3 is 2 mm or more and 4 mm or less.
This is because if the hydraulic diameter of the flat tube 20 of the indoor heat exchanger 2 is 0.5 mm or less, the pressure loss in the pipe of the indoor heat exchanger 2 increases, and the efficiency of the air conditioner decreases significantly. It is. In addition, if the hydraulic diameter of the flat tube 20 of the indoor heat exchanger 2 is 2 mm or more, the refrigerant flow rate in the pipe of the indoor heat exchanger 2 is slowed down, and the efficiency of the air conditioner is significantly reduced.

  By setting the hydraulic diameter of the flat tube 20 of the indoor heat exchanger 2 as described above, the heat transfer performance of the indoor heat exchanger 2 can be further improved, and the highly efficient outdoor heat exchanger 3 can be improved. Can be obtained.

  The present invention is not limited to an air conditioner, and may be applied to other refrigeration cycle apparatuses having a heat exchanger that constitutes a refrigerant circuit, such as a refrigeration apparatus and a heat pump apparatus, and has an evaporator and a condenser. Can do.

  2 indoor side heat exchanger, 3 outdoor side heat exchanger, 5 compressor, 7 expansion valve, 8 four-way valve, 10 fin, 20 flat tube, 21 refrigerant flow path, 30 circular tube.

Claims (8)

A refrigerant circuit that sequentially connects a compressor, an outdoor heat exchanger mounted on the outdoor unit, an expansion means, and an indoor heat exchanger mounted on the indoor unit with a pipe to circulate the refrigerant;
The outdoor heat exchanger and the indoor heat exchanger are:
A plurality of fins arranged at predetermined intervals and airflow between them;
A heat transfer tube that is inserted through the fin and through which the refrigerant flows,
The heat exchanger tube of the outdoor heat exchanger is a flat tube having a flat cross section, and is arranged so that the long direction of the flat shape faces the flow direction of the airflow, the long tube of the flat shape The length is configured to be 14 mm or more and 22 mm or less,
The ratio between the flow rate of the refrigerant flowing through the heat transfer tube of the indoor heat exchanger and the flow rate of the refrigerant flowing through the heat transfer tube of the outdoor heat exchanger is configured to be larger than 2.3 and smaller than 11.6. An air conditioner characterized by being made. The ratio of the flow rate of the refrigerant flowing through the heat transfer tube of the indoor heat exchanger and the flow rate of the refrigerant flowing through the heat transfer tube of the outdoor heat exchanger is larger than 2.3 and smaller than 11.6. The air conditioner according to claim 1, wherein the cross-sectional area and the number of passes of the heat transfer tubes of the outdoor heat exchanger and the indoor heat exchanger are set. A plurality of indoor heat exchangers;
The ratio of the sum of the flow rates of the refrigerant flowing through the heat transfer tubes of the indoor heat exchangers to the flow rate of the refrigerant flowing through the heat transfer tubes of the outdoor heat exchanger is greater than 2.3. 3. The air conditioner according to claim 1, wherein the air conditioner is configured to be smaller . The air conditioner according to any one of claims 1 to 3, wherein the heat transfer tube of the indoor heat exchanger is a circular tube having a circular cross section. The circular tube of the indoor heat exchanger has a diameter of 4 mm to 6.35 mm,
The air conditioner according to claim 4, wherein the flat tube of the outdoor heat exchanger has a hydraulic diameter of 2 mm or more and 4 mm or less. The air conditioner according to any one of claims 1 to 3, wherein the heat transfer tube of the indoor heat exchanger is a flat tube having a flat cross section. The flat tube of the indoor heat exchanger has a hydraulic diameter of 0.5 mm or more and less than 2 mm,
The air conditioner according to claim 6, wherein the flat tube of the outdoor heat exchanger has a hydraulic diameter of 2 mm or more and 4 mm or less. The air conditioner according to any one of claims 1 to 7, wherein any one of HC single refrigerant, a mixed refrigerant containing HC, R32, R410A, R407C, and carbon dioxide is used as the refrigerant. .

Images