JP4922669B2 - Air conditioner and heat exchanger for air conditioner - Google Patents

Description

  The present invention relates to an air conditioner that uses a vapor compression refrigeration cycle, and is suitable for achieving both compactness and high efficiency and achieving maximum performance in a limited installation space.

  In an air conditioner, it is desirable to reduce the outside diameter of the heat source side (outdoor unit) with respect to the cooling / heating capacity from the viewpoint of improving transportability, restrictions on installation space, and recyclability at the time of disposal. In particular, at the time of renewal of existing air conditioning equipment, due to the rapid spread of OA equipment in recent years, the target air conditioning load has increased significantly compared to before the renewal, and a larger air conditioning capacity is required in the existing installation space. As a means for reducing the outer diameter, the outdoor fan whose air-cooling standard capacity is 14 to 16 kW and whose outer diameter is 600 to 700 mm when viewed from the front side is improved by improving the performance of the blower fan. It is disclosed in Patent Document 1 (Japanese Patent No. 3491500) that the unit and an outdoor unit having a cooling standard capacity of 22 to 28 kW and an outer diameter dimension of 900 to 1200 mm as viewed from the front side are configured. Are listed. Moreover, in order to achieve downsizing of the outdoor unit, it is necessary to increase the efficiency of not only the blower but also the heat exchanger. Patent Document 2 (Distribution of parallel heat exchangers installed in parallel from the leeward side to the leeward side) (Patent No. 3219506).

Japanese Patent No. 3491500 Japanese Patent No. 3219506

  In order to realize a compact and high-performance outdoor unit, it is necessary to improve not only the fan performance but also the heat source side heat exchanger, and it is important to secure a large heat transfer area in the same installation space.

  Conventionally, in heat exchangers mainly used for store and building air conditioners, fin-tube heat exchangers that are arranged in two rows in parallel with the air flow of the blower, in which fins are combined with U-shaped heat transfer pipes, are used. It is common. In this case, since the installation area depends on the form of the blower and the arrangement of the heat exchangers, if the form of the blower does not change, the means for improving the size and performance of the heat exchanger is the number of rows of heat exchangers arranged in parallel. The method of increasing is easy.

  In the heat source side heat exchanger, by arranging two rows of heat exchangers in three rows, a heat transfer area of 1.5 times can be secured without changing the length around the heat exchanger that greatly affects the installation area. Can contribute to the downsizing of air conditioners. However, when the number of heat exchangers on the heat source side is increased from two rows to three rows, the length of the heat transfer tube inserted into the heat exchanger is also increased by 1.5 times, so that pressure loss due to passage resistance increases. This is because when the heat source side heat exchanger is used as an evaporator during heating, the fin surface temperature of the heat exchanger decreases due to a decrease in the evaporation pressure, causing frost formation on the fin surface and greatly reducing the heat exchanger performance. Let In particular, in a heat exchanger of an outdoor unit mainly used in air conditioning for buildings, where the performance of the heat source side heat exchanger exceeds 20 kW at the cooling standard time, the performance reduction due to frost formation is noticeable.

  Also, when the air flows through the first, second, and third rows of the heat exchanger as viewed from the windward side of the air flow of the blower, the air temperature fluctuates due to heat transfer with the heat exchanger on the windward side. However, the heat exchanger performance tends to decrease toward the leeward side in the blowing direction. Therefore, in order to make maximum use of the heat exchange performance of the three-row heat exchanger, the air flow direction of the blower must also be considered.

  The objective of this invention is providing the air conditioner provided with the heat exchanger for solving the subject of the said prior art and utilizing the heat exchanger performance in the limited installation space to the maximum.

  In order to solve the above problems, in one embodiment of the present invention, a compressor, a four-way valve, a heat source side heat exchanger, an outdoor expansion device, an outdoor unit including an outdoor blower, an electric expansion valve, a use side heat exchanger, an indoor In an air conditioner in which an indoor unit equipped with a blower is connected by a liquid connection pipe and a gas connection pipe, the heat source side heat exchanger is a fin tube type heat exchanger having three or more rows, and the heat source side heat exchanger The pipes are arranged so that the direction of the refrigerant flow in the pipe is opposed to the airflow direction of the blower during cooling, and the direction of the refrigerant flow through the pipe is parallel to the airflow direction of the blower during heating. .

  Further, in the above configuration, when the heat source side heat exchanger is used as a heating evaporator, the outlet of the Nth column from the upstream side in the refrigerant flow direction (N ≧ 1) to the inlet of the N + 1th column And a bifurcating branch at the inlet of the (N + 2) -th row piping, and the amount of refrigerant flowing in the (N + 1) -th row piping is preferably larger than the amount of refrigerant flowing in the N + 2-th row piping. .

  Further, in the above configuration, when the heat source side heat exchanger is used as a heating evaporator, the Nth column outlet (N ≧ 1) to the N + 1th column inlet and N + 2 from the upstream side in the refrigerant flow direction. It has a bifurcated branch at the inlet of the pipe in the row, and the amount of refrigerant flowing through the N + 1 row pipe is 0.5 to 0.6 with respect to the amount of refrigerant flowing through the N row pipe. Is desirable.

  Further, in the above configuration, when the heat source side heat exchanger is used as a heating evaporator, the outlet of the Nth column from the upstream side in the refrigerant flow direction (N ≧ 1) to the inlet of the N + 1th column Further, it is desirable that the pipe is branched into two at the inlet of the N + 2 row pipe, and the N + 2 row pipe is branched from the N + 1 row pipe.

  Further, in the above configuration, when the heat source side heat exchanger is used as a heating evaporator, the outlet of the Nth column from the upstream side in the refrigerant flow direction (N ≧ 1) to the inlet of the N + 1th column Further, it is desirable that the N + 2 row pipe be branched into two at the inlet of the N + 2 row pipe, and the N + 2 row pipe be branched from the N + 1 row pipe.

  Further, it is desirable that the N + 2 row pipe branches from the N + 1 row pipe at an angle of 60 degrees or more.

  Further, it is desirable that the N + 2th line pipe branches vertically from the N + 1th line pipe.

  Furthermore, in the above configuration, it is desirable that the refrigerant flowing in the pipe is a mixed refrigerant in which two or more kinds of non-chlorinated fluorocarbons are mixed.

  Further, in the above configuration, when the heat source side heat exchanger is used as a heating evaporator, the outlet of the Nth column piping (N ≧ 1) on the upstream side in the refrigerant flow direction to the inlet of the N + 1th column piping The refrigerant distribution ratio of each of the inlet of the N + 1 row and the inlet of the N + 2 row is adjusted by branching into the inlet of the N + 2 row of the pipe and adjusting the diameter of the branch joint portion with the branch main flow side. Is preferably adjustable.

  According to the present invention, since the maximum heat exchanger performance can be utilized in a limited installation space, it is possible to propose an air conditioner that achieves both compactness and high efficiency. It is suitable for enhancing the air conditioning capability.

Embodiments of the present invention will be described below with reference to the drawings.
In FIG. 1, the outdoor unit 13 has a variable capacity compressor 1 and a fixed capacity compressor 2 which are controlled by varying an operating frequency with an inverter, and each compressor is connected in parallel to a four-way valve 3. . The four-way valve 3 is connected to the heat source side heat exchanger 4 by piping, and is connected from the heat source side heat exchanger 4 to the refrigerant quantity regulator 7 via the outdoor expansion device 5. In addition, 6 is an electric valve that switches the flow path to the heat source side heat exchanger 4, and 8 is an outdoor fan that blows air to the heat source side heat exchanger 4.
Further, 9 is an electric expansion valve, 10 is a use side heat exchanger, 11 is an indoor blower, and constitutes an indoor unit 12. The indoor unit 12 is connected to the outdoor unit 13 through a liquid connection pipe 14 and a gas connection pipe 15. The variable capacity compressor 1, the fixed capacity compressor 2, the outdoor unit blower 8, and the indoor blower 11 are operated to exchange heat with the air, thereby performing indoor air conditioning.

  Next, the operation of the present embodiment will be described.

In the case of cooling operation, the refrigerant flows in the direction of the solid arrow in the figure, and the gas refrigerant discharged from the variable capacity compressor 1 and the fixed capacity compressor 2 passes through the four-way valve 3 and is a heat source configured by a plurality of refrigerant passages. It condenses in the side machine heat exchanger 4. The condensed refrigerant enters the refrigerant amount adjustment rod 7 and the liquid refrigerant derived from the refrigerant amount adjustment rod 7 is gasified by a pressure loss corresponding to the pipe length in the liquid connection pipe 14 connecting the outdoor unit 13 and the indoor unit 12. The electric expansion valve 9 enters the liquid two-phase flow.
The electric expansion valve 9 is an expansion device in which an arbitrary throttle amount can be set. The refrigerant decompressed by the electric expansion valve 9 is sent to the use side heat exchanger 10 serving as an evaporator, where it evaporates and the indoor air is cooled. The The evaporated refrigerant passes through the gas connection pipe 15 and returns to the suction side of the compressors 1 and 2.

In the case of heating operation, by switching the four-way valve 3, the refrigerant flows in the direction of the dotted arrow in the figure, and the refrigerant discharged from the variable capacity compressor 1 and the fixed capacity compressor 2 is the four-way valve 3, gas connection piping. 15, heat is dissipated and condensed in the use side heat exchanger 10 to heat the room.
The condensate is squeezed and expanded by the electric expansion valve 9, and is transferred to the outdoor unit 13 as a gas-liquid two-phase flow in the liquid connection pipe 14, and the refrigerant having a greater degree of cuteness due to the pressure loss of the liquid connection pipe 14 is a heat source. It is sent to the side heat exchanger 4. The refrigerant sent to the heat source side heat exchanger 4 evaporates to have a large degree of cuteness, passes through the four-way valve 3, and returns to the variable displacement compressor 1 and the fixed displacement compressor 2.

FIG. 2 shows a model of the heat source side heat exchanger of the comparative example. The heat transfer amount Q between the fin and air is
Q = U × ΔTln × A
Q: Heat transfer [W]
U: Heat transfer coefficient [W ・ m ^-2・ K ^-1 ]
A: Heat transfer area [m ² ]
ΔTln: Logarithmic average temperature difference [K]; ΔTln = (ΔT1−ΔT2) / {ln (ΔT1 / ΔT2)}
ΔT1, ΔT2: Fin surface temperature and air temperature difference (described in FIG. 3)
It is represented by

  As shown in FIG. 3, in order to maximize the logarithmic average temperature difference ΔTln between the fin surface temperature and the air, a heat exchanger is used for the air flow of the blower so as to be a condensing counterflow during cooling and an evaporating parallel flow during heating. Arrange the passage.

  In the case of FIG. 2, for example, when a building outdoor unit whose heat exchange amount exceeds 20 kW at the cooling standard time, the length of the heat exchanger per row may exceed 1000 mm, especially during heating, the pressure in the heat exchanger Decreasing evaporation pressure due to loss causes frost formation from the fin surface temperature, greatly reducing the heat exchange performance of the heat source side heat exchanger.

  FIG. 4 shows a model of a three-row heat exchanger according to the present invention. In order to reduce the pressure loss in the heat exchanger passage during heating, the refrigerant is allowed to flow in parallel from the first row outlet to the second row inlet and the third row inlet in FIG. The outlet passage at the time of heating can be doubled with respect to the heat exchanger model, which is suitable for avoiding problems due to the frost formation.

  Further, since the heat source side heat exchanger serves as a condenser during cooling, the area of the outlet passage is halved with respect to the heat exchanger inlet passage, so the flow rate of refrigerant flowing in the third row is doubled. The heat transfer coefficient between the heat exchanger heat transfer tube and the refrigerant can be improved.

  In addition, since the heat source side heat exchanger becomes an evaporating parallel flow during heating, the temperature of the air passing through the heat exchanger decreases as it moves to the second and third rows of heat exchangers that are leeward. I will do it. Therefore, if the heat exchange amounts in the second and third rows of the heat exchanger are Q2 and Q3, respectively, Q2> Q3. Therefore, by flowing more refrigerant through the second row of heat exchangers, where the heat exchange amount is larger than the third row of heat exchangers, the overheating area is expanded due to insufficient refrigerant circulation at the outlet of the second row of heat exchangers. The maximum performance as a heat exchanger can be achieved. In addition, the expansion of the superheated region causes a decrease in the evaporation pressure due to pressure loss, lowers the outlet temperature of the third row of heat exchangers, and may lead to frost formation, which is also suitable for avoiding frost formation.

  FIG. 5 shows a change example of the heat exchange amount when the ratio of the refrigerant circulation rate at the second-row inlet and the third-row inlet of the heat source side heat exchanger according to the embodiment of the present invention is changed. When the ratio of the refrigerant circulation amount flowing in the second row of the heat exchanger to the total refrigerant circulation amount is n (n = refrigerant circulation amount in the second row of heat exchanger / total refrigerant circulation amount), n = 0.5-0. The amount of heat exchange is high in the region 6, and it is necessary to distribute the refrigerant circulation amounts in the second and third rows within this range.

  In order to realize the refrigerant distribution of the heat source side heat exchanger, a bifurcated pipe is necessary. However, in the normal Y-shaped branch shape as shown in FIG. Since it becomes easier to flow, performance degradation occurs.

FIG. 7 shows the shape of the refrigerant pipe that enables the refrigerant branching of the heat source side heat exchanger in the present invention. By branching vertically from the mainstream straight line of the branch pipe, it is possible to avoid the influence of centrifugal force and ideal distribution is possible. The refrigerant distribution ratio can be adjusted by changing the hole diameter of the joint between the main stream side and the branched pipe, and can be realized with an inexpensive and easy structure. In the embodiment of FIG. 7, the third row of pipes branches vertically from the main flow part of the branch pipe, but the angle of the pipe branching from the branch main flow pipe to the main flow pipe is 60 degrees or more and 100 degrees or less. For example, it is considered that the refrigerant flowing in the mainstream pipe is larger than the refrigerant flowing in the branch pipe, and the heat exchange performance can be improved as compared with the case where the Y-type pipe of FIG.

  FIG. 8 shows a model of a 4-row and 5-row heat exchanger according to the present invention. In the case of a four-row heat exchanger, the pressure loss in the heat exchanger passage during heating can be reduced by using the branch piping shown in FIG. 7 for the third and fourth row branches. The same improvement effect as the heat exchanger model shown in FIG. In the case of a 5-row heat exchanger, the heat exchanger inlet during heating is distributed to the 1st and 3rd rows by a distributor such as a distributor, so that the 2-row heat exchanger and the 3-row heat exchanger heat exchanger It becomes a combination, and the same improvement effect as the heat exchanger model shown in FIG. 4 can be obtained. Therefore, the maximum performance as a heat exchanger can be exhibited by using the branch pipe according to the present invention in a multiple-row heat exchanger of three or more rows. Moreover, it is suitable also in avoiding frost formation by making it the structure which prevents the evaporating pressure fall by the pressure loss in a heat exchanger, and can prevent the fall of heat exchanger exit temperature.

  FIG. 9 shows a mounting example of the branch pipe shown in FIG. 7 in the heat source side heat exchanger in the embodiment of the present invention, and FIG. 10 shows an air conditioner in which the heat source side heat exchanger and the blower in the embodiment of the present invention are arranged. The outline drawing of is shown.

  In FIG. 10, the heat source side heat exchanger shown in FIG. 9 is configured so as to surround the blower, and is arranged so that the flow of air efficiently passes through the heat exchanger. Moreover, since the pipe connections of the heat source side heat exchanger can be concentrated on one side, the refrigerant pipes in the air conditioner housing can be compactly gathered.

  FIG. 11 shows a case where a plurality of the outdoor units are combined. By connecting the air conditioners with external piping, a larger capacity air conditioning facility can be realized with one refrigerant system. In this case, by using an air conditioner equipped with the heat source side heat exchanger, a larger number of air conditioners can be arranged in a limited space. Can cope with the increase. In addition, the unit of one outdoor unit can be made small, so it is superior in terms of transportability and recyclability.

  The figure at the time of using it as a larger capacity | capacitance heat exchanger by using two or more said heat source side heat exchangers of a different shape in FIG. 12 is shown. In this case, unlike the case of FIG. 10, it is not necessary to perform connection work between the outdoor units outside, the work period can be shortened, and this is an advantageous configuration in terms of safety.

  According to the embodiment of the present invention, the heat source side heat exchanger at the time of heating is less likely to be frosted, the deterioration of comfort due to defrosting is suppressed, and the refrigerant fluctuation due to the reverse cycle operation for defrosting is suppressed. As a result, reliability can be ensured. Since frost formation during heating becomes a big problem particularly when a mixed refrigerant in which two or more kinds of non-chlorinated fluorocarbons are mixed is used as a refrigerant, the present invention particularly relates to an air conditioner using a mixed refrigerant of non-chlorinated fluorocarbons. It is suitable for.

The block diagram of the refrigerating cycle which shows one embodiment by this invention. The figure which shows the 3 row heat exchanger model of a comparative example. The figure which shows the temperature distribution by one Embodiment of this invention. The figure which shows the heat exchanger model by one embodiment of this invention. Heat exchange performance comparison chart by refrigerant distribution ratio. The figure which shows the structure of the branch piping of a comparative example. The figure of the structure of the branch piping by one embodiment of the present invention. The figure which shows the 4-row and 5-row heat exchanger model by this invention. The figure which shows the external shape of the heat exchanger by one embodiment of this invention. The figure which shows the external shape of the air conditioner by one embodiment of this invention. The figure which shows the external shape of the external connection type air conditioner by one embodiment of this invention. The figure which shows the piping external shape in integrated air-conditioner machine by one embodiment of this invention.

Explanation of symbols

1 ... Variable capacity compressor, 2 ... Fixed capacity compressor, 3 ... Four-way valve, 4 ... Heat source side heat exchanger, 5 ... Outdoor expansion device, 6 ... Motorized valve, 7 ... Refrigerant amount regulator, 8 ... Outdoor Blower, 9 ... Electric expansion valve, 10 ... Use side heat exchanger, 11 ... Indoor fan, 12 ... Indoor unit, 13 ... Outdoor unit, 14 ... Liquid connection pipe, 15 ... Gas connection pipe, 16 ... Heat source side heat exchanger Heat transfer pipe, 17 ... Heat source side heat exchanger fins, 18 ... Heat source side heat exchanger heat transfer pipes, 19 ... Heat source side heat exchanger fins, 20 ... Heat source side heat exchanger branch pipe section, 21 ... Branch pipe refrigerant distribution Adjustment hole, 22 ... Heat source side heat exchanger, 23 ... Branch pipe, 24 ... Outdoor fan, 25 ... Heat source side heat exchanger, 26 ... Compressor, 27 ... Outdoor unit, 28 ... Liquid connection pipe, 29 ... Gas connection Piping, 30 ... heat source side heat exchanger, 31 ... compressor.

Claims (13)

Liquid connection piping and gas connection between compressor, four-way valve, heat source side heat exchanger, outdoor expansion device, outdoor unit equipped with outdoor blower and electric expansion valve, use side heat exchanger, indoor unit equipped with indoor blower In air conditioners connected by piping,
The heat source side heat exchanger is a fin tube type heat exchanger having three or more rows, and the direction of the refrigerant flow in the pipe of the heat source side heat exchanger is opposed to the wind direction of the outdoor fan during cooling. The piping is arranged, and the piping is arranged so that the direction of the flow of the refrigerant flowing through the piping during heating is parallel to the wind direction of the outdoor blower ,
Before SL when the heat source side heat exchanger is used as an evaporator in the heating, inlet and N + 2 columns from the upstream side of the flow direction of the refrigerant from the outlet of the N-th column of the pipe (N ≧ 1) of the N + 1 row pipe It has a bifurcated branch at the inlet of the second pipe, and the amount of refrigerant flowing in the N + 1th row of piping is larger than the amount of refrigerant flowing in the N + 2th row of piping. Air conditioner. In Claim 1 , when the said heat-source side heat exchanger is used as an evaporator at the time of heating, from the upstream of the refrigerant | coolant flow direction, the N-th row | line | column exit (N> = 1) to the inlet of the N + 1-th row piping and N + 2 A bifurcating branch is provided at the inlet of the pipe in the row, and the amount of refrigerant flowing in the pipe in the N + 1 row is set to 0.5 to 0.00 with respect to the amount of refrigerant flowing in the pipe in the N row. 6 is an air conditioner. In Claim 1 , when the said heat source side heat exchanger is used as an evaporator at the time of heating, from the upstream of the flow direction of a refrigerant | coolant, the exit (N> = 1) of the Nth line piping of the N + 1th line piping An air conditioner having a structure that bifurcates into an inlet and an inlet of an N + 2 row pipe, and the N + 2 row pipe branches from the N + 1 row pipe. 4. The air conditioner according to claim 3 , wherein the N + 2 row pipe branches from the N + 1 row pipe at an angle of 60 degrees to 110 degrees. 5. The air conditioner according to claim 4 , wherein the pipe in the (N + 2) th row branches substantially vertically from the pipe in the (N + 1) th row. The air conditioner according to claim 2 , wherein the refrigerant flowing in the pipe is a mixed refrigerant in which two or more kinds of non-chlorinated fluorocarbons are mixed. In Claim 1 , when the said heat source side heat exchanger is used as an evaporator at the time of heating, it is the inlet of the N + 1th line from the outlet (N ≧ 1) of the Nth line on the upstream side in the refrigerant flow direction. Each of the refrigerants at the inlet of the (N + 1) th line and at the inlet of the (N + 2) th line by branching to the inlet of the N + 2th line and adjusting the diameter of the branch joint portion with the branch main flow side. An air conditioner characterized in that the distribution ratio can be adjusted. The number of rows of heat exchangers is three or more, the direction of the refrigerant flow in the pipe of the heat exchanger is opposed to the direction of the wind of the outdoor fan during cooling, and the refrigerant flowing through the pipe during heating The piping is arranged so that the flow direction is parallel to the wind direction of the outdoor blower ,
When the heat source side heat exchanger is used as an evaporator at the time of heating, the outlet of the Nth column from the upstream side in the refrigerant flow direction (N ≧ 1) to the inlet of the N + 1th column and the N + 2th column The air is characterized in that it has a bifurcated branch at the inlet of the pipe, and the amount of refrigerant flowing in the N + 1th row of piping is larger than the amount of refrigerant flowing in the N + 2th row of piping. The heat exchanger of the harmony machine. In Claim 8 , When the said heat-source side heat exchanger is used as an evaporator at the time of heating, from the upstream of the flow direction of a refrigerant | coolant, the N line exit (N> = 1) to the N + 1 line piping inlet and A bifurcating branch is provided at the inlet of the (N + 2) -th row pipe, and the amount of refrigerant flowing through the (N + 1) -th row pipe is set to 0.5 to 0 with respect to the amount of refrigerant flowing through the N-th row pipe. An air conditioner heat exchanger characterized by .6. In Claim 8 , When the said heat source side heat exchanger is used as an evaporator at the time of heating, from the upstream of the flow direction of a refrigerant | coolant, the exit (N> = 1) of the Nth line piping of the N + 1th line piping An air conditioner heat exchanger characterized by having a structure bifurcated into an inlet and an inlet of an N + 2 row pipe, wherein the N + 2 row pipe branches from the N + 1 row pipe. 11. The heat exchanger for an air conditioner according to claim 10 , wherein the pipe in the (N + 2) th row branches from the pipe in the (N + 1) th row at an angle of 60 degrees to 110 degrees. 11. The heat exchanger for an air conditioner according to claim 10 , wherein the pipe in the (N + 2) th row branches vertically from the pipe in the (N + 1) th row. 9. The heat exchanger for an air conditioner according to claim 8 , wherein the refrigerant flowing in the pipe is a mixed refrigerant obtained by mixing two or more kinds of non-chlorinated fluorocarbons.

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