GB2542971A

GB2542971A - Air conditioning apparatus

Info

Publication number: GB2542971A
Application number: GB1622015.4A
Authority: GB
Inventors: Najima Kohei; Morishita Yuya
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2014-07-01
Filing date: 2014-07-01
Publication date: 2017-04-05
Anticipated expiration: 2034-07-01
Also published as: WO2016002009A1; GB201622015D0; JP6272481B2; JPWO2016002009A1; GB2542971B

Abstract

This air conditioning apparatus is provided with: a flow rate adjustment apparatus (42), which is provided on a bypass circuit (41), and which adjusts the quantity of a cooling medium flowing on the bypass circuit (41); a housing (10a) having a heat source-side heat exchanger (5) mounted thereon; a base heat exchanger (43) that is provided on the bypass circuit (41), said heat exchanger being on the bottom surface (10a1) of the housing (10a); and a control means (91) that controls the opening degree of the flow rate adjustment apparatus (42). A drain hole (10a2) is provided in the bottom surface (10a1) of the housing (10a).

Description

DESCRIPTION Title of Invention AIR-CONDITIONING APPARATUS Technical Field [0001]

The present invention relates to an air-conditioning apparatus.

Background Art [0002] A conventional air-conditioning apparatus including an outdoor unit provided outside a building, an indoor unit provided inside the building, and a refrigerant circuit that connects the outdoor unit and the indoor unit is known (e.g., Patent Literature 1 to 3).

Citation List Patent Literature [0003]

Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2005-337658 (e.g., Fig. 1)

Patent Literature 2: Japanese Unexamined Patent Application Publication No. 2005-337657 (e.g., Fig. 1)

Patent Literature 3: Japanese Unexamined Patent Application Publication No. 2005-337661 (e.g., Fig. 1)

Summary of Invention Technical Problem [0004]

An example of the air-conditioning apparatus includes, for example, a multi-air-conditioning apparatus for a building. The multi-air-conditioning apparatus for a building includes a compressor that is provided inside an outdoor unit and that serves as a heat source. The multi-air-conditioning apparatus for a building also includes a heat source side heat exchanger provided inside the outdoor unit and a use side heat exchanger provided inside an indoor unit. The bottom surface of the housing that constitutes the outdoor unit of the multi-air-conditioning apparatus for a building has drain holes. The drain holes are openings for draining, to the outside of the outdoor unit, drainage water generated from condensation formed on the heat source side heat exchanger and flowing downward.

[0005]

The multi-air-conditioning apparatus for a building can operate in a heating operation mode for heating an indoor space and in a cooling operation mode for cooling the indoor space. In the heating operation mode, refrigerant circulating through a refrigerant circuit receives heat by heat exchange with outside air supplied to the heat source side heat exchanger. Then, the refrigerant transfers the heat to air supplied to the use side heat exchanger by heat exchange with the air, thereby heating the air to be sent to an air-conditioned space. In the cooling operation mode, the refrigerant circulating through the refrigerant circuit receives heat by heat exchange with the air supplied to the use side heat exchanger and cools the air to be sent to the air-conditioned space. Then, the refrigerant transfers the heat to the outside air supplied to the heat source side heat exchanger by heat exchange with the outside air.

[0006]

When outside air humidity is high, for example, during winter, condensation may form on the heat source side heat exchanger and drainage water may flow downward in the heating operation mode in which the heat source side heat exchanger functions as an evaporator. The flowing drainage water may freeze at the drain holes due to the low outside air temperature. If the drainage water freezes at the drain holes, the drain holes become clogged and cannot drain the drainage water. This may result in growth of ice on the bottom surface of the housing of the outdoor unit. If the ice grows on the bottom surface of the housing of the outdoor unit, problems as described below may arise. For instance, the operation performance of the air-conditioning apparatus may decrease, rupture of a refrigerant pipe may cause a gas leakage, and other problems may arise. In view of this, attaching an electric heater to the bottom surface of the housing of the outdoor unit is a measure to suppress the drainage water from freezing at the drain holes.

[0007]

However, since power needs to be supplied to the electric heater to melt the ice with the electric heater, power consumption increases. Moreover, if the electric heater breaks, the heating performance is lost.

[0008]

In view of the problems, the objective of the present invention is to obtain an air-conditioning apparatus that has better drainage of drainage water compared with the conventional technique, has decreased power consumption, and does not lose heating performance.

Solution to Problem [0009]

An air-conditioning apparatus according to an aspect of the present invention includes: a main circuit in which at least a compressor, a use side heat exchanger, an expansion device, and a heat source side heat exchanger are connected sequentially by pipes; a bypass that diverges from the main circuit at a branch portion positioned on the outlet side of the compressor and on the inlet side of the use side heat exchanger, and that joins the main circuit at a junction portion positioned on the outlet side of the expansion device and on the inlet side of the heat source side heat exchanger; a flow rate adjusting device that is provided in the bypass and that adjusts the amount of refrigerant flowing through the bypass; a housing accommodating the heat source side heat exchanger; a base heat exchanger provided in the bypass and on the bottom surface of the housing; and a control unit that controls the opening degree of the flow rate adjusting device, in which the bottom surface of the housing has an opening. Advantageous Effects of Invention [0010]

According to an aspect of the present invention, the base heat exchanger is provided in the bypass, to which high-temperature refrigerant discharged from the compressor is supplied, and heats portions around drain holes. This can suppress the possibility of drainage water freezing at the drain holes, thereby realizing better drainage of the drainage water compared with the conventional technique. Moreover, since the portions around the drain holes are heated with the base heat exchanger, power consumption does not increase. Since the base heat exchanger does not break, there is no possibility that the heating performance is lost.

Brief Description of Drawings [0011] [Fig. 1] Fig. 1 illustrates a configuration example of a refrigerant circuit of an air-conditioning apparatus 100 according to Embodiment 1 of the present invention.

[Fig. 2] Fig. 2 illustrates an example of the shape of a housing 10a of the air-conditioning apparatus 100 according to Embodiment 1 of the present invention.

[Fig. 3] Fig. 3 illustrates an example of the shape of a bottom surface 10a1 of the air-conditioning apparatus 100 according to Embodiment 1 of the present invention.

[Fig. 4] Fig. 4 is a perspective view of a heat source side heat exchanger 5 and the bottom surface 10a1 of the air-conditioning apparatus 100 according to Embodiment 1 of the present invention.

[Fig. 5] Fig. 5 is a side view of the heat source side heat exchanger 5 and the bottom surface 10a1 of the air-conditioning apparatus 100 according to Embodiment 1 of the present invention.

[Fig. 6] Fig. 6 is a side view illustrating an example of positioning of a base heat exchanger 43 of the air-conditioning apparatus 100 according to Embodiment 1 of the present invention.

[Fig. 7] Fig. 7 is a configuration example of the refrigerant circuit in a cooling operation mode of the air-conditioning apparatus 100 according to Embodiment 1 of the present invention.

[Fig. 8] Fig. 8 is a configuration example of the refrigerant circuit in a heating operation mode of the air-conditioning apparatus 100 according to Embodiment 1 of the present invention.

[Fig. 9] Fig. 9 is a flowchart illustrating control of the base heat exchanger 43 of the air-conditioning apparatus 100 according to Embodiment 1 of the present invention.

Description of Embodiments [0012]

Embodiment 1

Details of an air-conditioning apparatus 100 of the present invention are described below with reference to the drawings. It should be noted that the sizes of structural components in the drawings referred to below may be different from the actual sizes. Moreover, in the drawings referred to below, structural components designated by identical reference signs are the same or corresponding components throughout the description. Furthermore, aspects of structural components described throughout the description are mere examples, and are not limited to these examples.

[0013]

Fig. 1 is a schematic diagram illustrating an example of positioning of the components of the air-conditioning apparatus 100 according to Embodiment.

The example of positioning of the components of the air-conditioning apparatus 100 is described below with reference to Fig. 1. The air-conditioning apparatus 100 has a refrigeration cycle for circulating refrigerant, and each indoor unit 20 can freely select a cooling mode or heating mode as an operation mode. The description of Fig. 1 below assumes a state in which a flow switching device 3 has changed a direction in which the refrigerant flows so that a heating operation is performed.

[0014]

As Fig. 1 illustrates, the air-conditioning apparatus 100 includes an outdoor unit 10, the indoor unit 20, an outside air temperature detecting unit (not illustrated), and an outside air humidity detecting unit (not illustrated). The outdoor unit 10 and the indoor unit 20 are connected by a refrigerant pipe 4.

The outside air temperature detecting unit is a temperature detecting unit for detecting the temperature of air outside the outdoor unit 10. The outside air humidity detecting unit is a humidity detecting unit for detecting the humidity of the air outside the outdoor unit 10.

[0015]

The outdoor unit 10 includes a compressor 1, a check valve 2, the flow switching device 3, a heat source side heat exchanger 5, and an accumulator 6.

The enclosure of the outdoor unit 10 serves as a housing 10a (Fig. 2). The shape and other details of the housing 10a are described later. The indoor unit 20 includes a use side heat exchanger 11, a use side air sending unit (not illustrated), an expansion device 12, and a control unit 91. It should be noted that the accumulator 6 is not an essential component of the air-conditioning apparatus 100.

[0016]

The compressor 1 is a variable capacity compressor that compresses suctioned refrigerant and discharges high-temperature, high-pressure refrigerant. The compressor 1 suctions and compresses the refrigerant flowing from the accumulator 6 and changes the state of the refrigerant to a high-temperature, high-pressure state. The compressor 1 includes, for example, a capacity-controllable inverter compressor. The check valve 2 prevents reverse flow of the refrigerant discharged from the compressor 1.

[0017]

The flow switching device 3 can change a direction in which the refrigerant discharged from the compressor 1 flows, in accordance with, for example, the implemented operation mode such as the heating operation mode or the cooling operation mode. With reference to Fig. 1, as an example, the following describes a case in which the flow switching device 3 has changed the direction in which the refrigerant flows so that the heating operation is performed.

[0018]

The use side heat exchanger 11 functions as an evaporator during the cooling operation and functions as a condenser during the heating operation.

The use side air sending unit supplies indoor air to the use side heat exchanger 11 and generates an air flow. The use side heat exchanger 11 exchanges heat between the refrigerant and the air supplied from an air sending unit such as the use side air sending unit (not illustrated). The expansion device 12 is a decompressing unit provided on the outlet side of the use side heat exchanger 11.

[0019]

The heat source side heat exchanger 5 functions as an evaporator during the heating operation and functions as a condenser during the cooling operation. A heat source side air sending unit supplies outside air to the heat source side heat exchanger 5 and generates an air flow. The heat source side heat exchanger 5 exchanges heat between the refrigerant and the air supplied from an air sending unit such as the heat source side air sending unit (not illustrated).

[0020]

The accumulator 6 accumulates surplus refrigerant generated due to a difference between refrigerant flowing in the heating operation mode and refrigerant flowing in the cooling operation mode or accumulates surplus refrigerant caused by a transient operation change or a load condition. The accumulator 6 is provided on the inlet side of the compressor 1. Here, the "transient operation change" means, for example, a change in the number of the indoor units 20 in operation. The accumulator 6 separates the refrigerant that has flowed into the accumulator 6 into a liquid phase containing a lot of high boiling point refrigerant and a gas phase containing a lot of low boiling point refrigerant. This allows the accumulator 6 to accumulate the liquid phase refrigerant containing a lot of high boiling point refrigerant. If a lot of liquid-phase refrigerant exists in the accumulator 6, the low boiling point refrigerant tends to form a large proportion of the refrigerant circulating through the refrigerant circuit.

[0021]

The configuration of a main circuit 31 is obtained by connecting the compressor 1, the check valve 2, the flow switching device 3, the use side heat exchanger 11, the expansion device 12, the heat source side heat exchanger 5, and the accumulator 6 sequentially with, for example, pipes. In the main circuit 31, a branch portion 51 is provided on the outlet side of the compressor 1 and on the inlet side of the use side heat exchanger 11 (the check valve 2 and the flow switching device 3). In the main circuit 31, a junction portion 52 is provided on the outlet side of the expansion device 12 and on the inlet side of the heat source side heat exchanger 5. A bypass 41 is provided so that the main circuit 31 of the branch portion 51 and the main circuit 31 of the junction portion 52 are connected.

[0022]

The bypass 41 diverges from the main circuit 31 at the branch portion 51, which is provided on the outlet side of the compressor 1 and on the inlet side of the use side heat exchanger 11. The bypass 41 joins the main circuit 31 at the junction portion 52, which is provided on the outlet side of the expansion device 12 and on the inlet side of the heat source side heat exchanger 5. In the bypass 41, a flow rate adjusting device 42, the base heat exchanger 43, and an opening and closing device 44 are provided in this order from the branch portion 51 toward the junction portion 52.

[0023]

The flow rate adjusting device 42 adjusts how much of the refrigerant that has flowed from the branch portion 51 into the bypass 41 passes through the flow rate adjusting device 42. The opening degree of the flow rate adjusting device 42 can be, for example, adjusted to more than one level. The base heat exchanger 43 is provided on the downstream side of the flow rate adjusting device 42. The base heat exchanger 43 functions as a condenser during the heating operation, exchanges heat with outside air, and transfers the heat to the outside air. Details of the base heat exchanger 43 are described later with reference to Fig. 6. The opening and closing device 44 functions as a check valve for suppressing the refrigerant flowing from the heat source side heat exchanger 5 during the cooling operation from flowing into the bypass 41.

[0024] A control unit 91 controls the opening degree of the flow rate adjusting device 42 on the basis of at least one of a result obtained with the outside air temperature detecting unit and a result obtained with the outside air humidity detecting unit. The control unit 91 is provided inside the indoor unit 20, for example. Specifically, for instance, the control unit 91 adjusts the opening degree of the flow rate adjusting device 42 on the basis of the result of detection by an outside air temperature sensor. More specifically, the control unit 91 decreases the opening degree of the flow rate adjusting device 42 as temperature detected by the outside air temperature sensor increases. That is, the control unit 91 increases the opening degree of the flow rate adjusting device 42 as the temperature detected by the outside air temperature sensor decreases.

[0025]

Moreover, for instance, when the air-conditioning apparatus 100 starts operating, the control unit 91 controls the use side air sending unit so as to rotate the use side air sending unit, and controls the heat source side air sending unit so as to rotate the heat source side air sending unit. The control unit 91 also controls the flow switching device 3 on the basis of an instruction to start the heating operation and an instruction to start the cooling operation.

[0026]

It should be noted that the control unit 91 is, for example, hardware such as a circuit device that realizes the functions of the control unit 91 or software running on an arithmetical unit such as a microcomputer or a CUP. The control unit 91 controls each component of the air-conditioning apparatus 100 on the basis of an operation signal sent from an operation unit such as a remote controller.

[0027]

Fig. 2 illustrates an example of the shape of the housing 10a of the air-conditioning apparatus 100 according to Embodiment 1 of the present invention. As Fig. 2 illustrates, the outdoor unit 10 includes the housing 10a. The housing 10a has, for example, an upward-blowing structure in which air obtained through heat exchange by the heat source side heat exchanger 5 is discharged from the top of the housing 10a. The housing 10a has, for example, a hexahedral (cuboid) shape. The bottom of the housing 10a is a bottom surface 10a1.

[0028]

Fig. 3 illustrates an example of the shape of the bottom surface 10a1 of the air-conditioning apparatus 100 according to Embodiment 1 of the present invention. As Fig. 3 illustrates, the bottom surface 10a1 is, for example, rectangular in plan view and is inclined, for example. The heat source side heat exchanger 5 is provided in the bottom surface 10a1. The heat source side heat exchanger 5 has, for example, a shape following the periphery of the bottom surface 10a1. The heat source side heat exchanger 5 is, for example, U-shaped. The bottom surface 10a1 has, for example, drain holes 10a2. It should be noted that the bottom surface 10a1 may be made of a non-inclined horizontal material.

[0029]

The drain hole 10a2 is an opening for discharging, to the outside of the outdoor unit 10, drainage water that has been generated from condensation formed on the heat source side heat exchanger 5 and has flowed downward on the surface of the heat source side heat exchanger 5. For instance, two or more drain holes 10a2 are provided. The drain holes 10a2 are provided at a portion of the bottom surface 10a1, which is inclined downward from a portion under the heat source side heat exchanger 5 toward the portion where the drain holes 10a2 are provided. The drain holes 10a2 are provided on the downstream side in a direction in which the drainage water, which has flowed downward on the surface of the heat source side heat exchanger 5, flows on the bottom surface 10a1. It should be noted that the "direction in which the drainage water, which has flowed downward on the surface of the heat source side heat exchanger 5, flows on the bottom surface 10a1" is a direction from the periphery of the bottom surface 10a1 toward the inside of the bottom surface 10a1 beyond the inner surface of the heat source side heat exchanger 5.

[0030]

Fig. 4 is a perspective view of the heat source side heat exchanger 5 and the bottom surface 10a1 of the air-conditioning apparatus 100 according to Embodiment 1 of the present invention. Fig. 5 is a side view of the heat source side heat exchanger 5 and the bottom surface 10a1 of the air-conditioning apparatus 100 according to Embodiment 1 of the present invention.

[0031]

Figs. 4 and 5 illustrate directions in which the drainage water flows when condensation is formed on the heat source side heat exchanger 5 functioning as an evaporator, during the heating operation and, for example, in a case in which the temperature falls below the freezing point in winter. The arrows in Figs. 4 and 5 denote the directions in which the drainage water flows. The drainage water generated on the heat source side heat exchanger 5 flows downward on the surface of the heat source side heat exchanger 5 and reaches the bottom surface 10a1. After reaching the bottom surface 10a1, the drainage water is discharged to the outside of the outdoor unit 10 through the drain holes 10a2.

[0032]

Fig. 6 is a side view illustrating an example of positioning of the base heat exchanger 43 of the air-conditioning apparatus 100 according to Embodiment 1 of the present invention. As Fig. 6 illustrates, the base heat exchanger 43 is provided in the bottom surface 10a1 and extended in an area more inward than an inward area of the bottom surface 10a1 enclosed with each of the centers of the drain holes 10a2, in consideration of the direction in which the drainage water flows. The base heat exchanger 43 is positioned on the air flow downstream side of the opening edge of the drain hole 10a2 closest to the heat source side heat exchanger 5. By providing the base heat exchanger 43 in this manner, it is possible to suppress deterioration of drainage at the drain holes 10a2 due to blocking the flow of the drainage water and to suppress the possibility of the drainage water freezing on the bottom surface 10a1 compared with the case in which the base heat exchanger 43 is positioned on the air flow upstream side of the opening edge of the drain hole 10a2 closest to the heat source side heat exchanger 5.

[0033]

Fig. 7 is a configuration example of the refrigerant circuit in the cooling operation mode of the air-conditioning apparatus 100 according to Embodiment 1 of the present invention. Fig. 8 is a configuration example of the refrigerant circuit in the heating operation mode of the air-conditioning apparatus 100 according to Embodiment 1 of the present invention.

[0034]

The following describes each operation mode performed by the air-conditioning apparatus 100 with reference to Figs. 7 and 8. If two or more indoor units 20 are provided, the air-conditioning apparatus 100 can perform the same operation for all the indoor units 20 on the basis of an instruction from each indoor unit 20.

[0035] [Cooling Operation Mode]

Fig. 7 is a configuration example of the refrigerant circuit in the cooling operation mode of the air-conditioning apparatus 100 according to Embodiment 1 of the present invention. It should be noted that the arrows in Fig. 7 denote directions in which refrigerant flows.

[0036]

As Fig. 7 illustrates, the control unit 91 causes the flow switching device 3 to change the direction in which the refrigerant flows so that the cooling operation is performed. Thus, low-temperature, low-pressure refrigerant flowing on the suctioning side of the compressor 1 flows into the compressor 1 and is compressed by the compressor 1. The refrigerant compressed by the compressor 1 becomes high-temperature, high-pressure gas refrigerant and is discharged from the compressor 1. The high-temperature, high-pressure gas refrigerant discharged from the compressor 1 flows into the heat source side heat exchanger 5 via the check valve 2 and the flow switching device 3. Here, the flow rate adjusting device 42 and the opening and closing device 44 are closed. Thus, the refrigerant discharged from the compressor 1 does not flow into the bypass 41, and heat is not exchanged by the base heat exchanger 43.

[0037]

After flowing into the heat source side heat exchanger 5, the refrigerant becomes high-pressure liquid refrigerant while transferring heat to outside air and flows from the heat source side heat exchanger 5. The high-pressure refrigerant flowing from the heat source side heat exchanger 5 is decompressed by the expansion device 12 and becomes low-temperature, low-pressure two-phase refrigerant. The low-temperature, low-pressure two-phase refrigerant flows into the use side heat exchanger 11, cools an indoor space by removing heat from indoor air, and flows from the use side heat exchanger 11. The refrigerant flowing from the use side heat exchanger 11 flows into the outdoor unit 10 again through the refrigerant pipe 4. After flowing into the outdoor unit 10, the refrigerant flows through the flow switching device 3 and the accumulator 6 in this order and is suctioned by the compressor 1 again.

[0038] [Heating Operation Mode]

Fig. 8 is a configuration example of the refrigerant circuit in the heating operation mode of the air-conditioning apparatus 100 according to Embodiment 1 of the present invention. It should be noted that the arrows in Fig. 8 denote directions in which the refrigerant flows.

[0039]

As Fig. 8 illustrates, the control unit 91 causes the flow switching device 3 to change the direction in which the refrigerant flows so that the heating operation is performed. Thus, the low-temperature, low-pressure refrigerant flowing on the suctioning side of the compressor 1 flows into the compressor 1 and is compressed by the compressor 1. The refrigerant compressed by the compressor 1 becomes high-temperature, high-pressure gas refrigerant and is discharged from the compressor 1. A portion of the high-temperature, high-pressure gas refrigerant discharged from the compressor 1 flows into the use side heat exchanger 11 via the check valve 2 and the flow switching device 3. Here, the flow rate adjusting device 42 and the opening and closing device 44 are open. Thus, a portion of the refrigerant discharged from the compressor 1 flows into the bypass 41 and then flows into the base heat exchanger 43.

[0040]

After flowing into the use side heat exchanger 11, the portion of the refrigerant becomes high-pressure liquid refrigerant while transferring heat to indoor air and flows from the use side heat exchanger 11. The high-temperature refrigerant flowing from the use side heat exchanger 11 is decompressed by the expansion device 12 and becomes low-temperature, low-pressure two-phase refrigerant. The low-temperature, low-pressure two-phase refrigerant flows into the heat source side heat exchanger 5, becomes low-temperature, low-pressure gas refrigerant by removing heat from outside air, and flows from the heat source side heat exchanger 5. The low-temperature, low-pressure gas refrigerant flowing from the heat source side heat exchanger 5 flows through the flow switching device 3 and the accumulator 6 in this order and is suctioned by the compressor 1 again.

[0041] A portion of the high-temperature, high-pressure refrigerant gas discharged from the compressor 1 that has not flowed toward the check valve 2 flows through the bypass 41. The refrigerant flowing through the bypass 41 flows through the flow rate adjusting device 42, the base heat exchanger 43, and the opening and closing device 44 in this order and joins the refrigerant flowing through the main circuit 31 at the junction portion 52. Here, after flowing into the base heat exchanger 43, the high-temperature, high-pressure gas refrigerant transfers heat to the bottom surface 10a1 and melts ice near the drain holes 10a2. It should be noted that preferably, the bottom surface 10a1 is made of a high thermal conductivity material such as a metal. The refrigerant condensed by the heat transfer flows through the opening and closing device 44 and joins the refrigerant flowing from the use side heat exchanger 11.

[0042]

Fig. 9 is a flowchart illustrating control of the base heat exchanger 43 of the air-conditioning apparatus 100 according to Embodiment 1 of the present invention. The following describes steps S101 to S123 with reference to Fig. 9.

[0043]

In step S101, the control unit 91 controls each component so that the heating operation is performed. For instance, the control unit 91 controls the flow switching device 3 and other components so that the heating operation is performed. Then, the procedure proceeds to step S102.

[0044]

In step S102, the control unit 91 determines whether or not the temperature of outside air is zero degrees Celsius or below. In step S102, if the control unit 91 determines that the temperature of the outside air is zero degrees Celsius or below (Yes in step S102), the procedure proceeds to step S111. Meanwhile, in step S102, if the control unit 91 determines that the temperature of the outside air is above zero degrees Celsius (No in step S102), the procedure proceeds to step S121.

[0045]

In step S111, the control unit 91 performs control so that the base heat exchanger 43 is turned on. Then, the procedure proceeds to step S112. In step S112, if the control unit 91 determines that the heating operation is being performed, the procedure goes back to step S102. In step S112, if the control unit 91 determines that the heating operation is not being performed, the procedure proceeds to step S113. In step S113, the control unit 91 performs control so that the base heat exchanger 43 is turned off.

[0046]

In step S121, the control unit 91 performs control so that the base heat exchanger 43 is turned off. Then, the procedure proceeds to step S122. In step S122, if the control unit 91 determines that the heating operation is being performed, the procedure goes back to step S102. In step S122, if the control unit 91 determines that the heating operation is not being performed, the procedure proceeds to step S123. In step S123, the control unit 91 performs control so that the base heat exchanger 43 is turned off.

[0047]

It should be noted that in the above explanation, "control so that the base heat exchanger 43 is turned on" means, for example, control of the flow rate adjusting device 42 in which the control unit 91 opens at least a portion of the flow rate adjusting device 42. It should be noted that in the above explanation, "control so that the base heat exchanger 43 is turned off' means, for example, control of the flow rate adjusting device 42 in which the control unit 91 closes the flow rate adjusting device 42.

[0048]

Thus, the air-conditioning apparatus 100 according to Embodiment 1 includes the flow rate adjusting device 42, the housing 10a, the base heat exchanger 43, and the control unit 91. The flow rate adjusting device 42 is provided in the bypass 41 and adjusts the amount of refrigerant flowing through the bypass 41. The housing 10a accommodates the heat source side heat exchanger 5. The base heat exchanger 43 is provided in the bypass 41 and on the bottom surface 10a1 of the housing 10a. The control unit 91 controls the opening degree of the flow rate adjusting device 42. The bottom surface 10a1 of the housing 10a has the drain holes 10a2.

The base heat exchanger 43 provided in the bypass 41, to which high-temperature refrigerant discharged from the compressor 1 is supplied, heats portions around the drain holes 10a2. This can decrease the possibility of drainage water freezing at the drain holes 10a2. Thus, the drainage of the drainage water is better than that with the conventional technique. Moreover, since the portions around the drain holes 10a2 are heated with the base heat exchanger 43, power consumption does not increase. Since the base heat exchanger 43 does not break, there is no possibility that the heating performance is lost.

[0049]

It should be noted that the above describes an example in which the base heat exchanger 43 is turned on at an outside air temperature of zero degrees Celsius or below, and the base heat exchanger 43 is turned off at an outside air temperature of above zero degrees Celsius. However, this is not the only example. For instance, a unit for detecting a physical value other than the outside air temperature may be provided, and the opening degree of the flow rate adjusting device 42 may be controlled on the basis of a detection result. For instance, the base heat exchanger 43 may be turned off at an outside air humidity of a predetermined value or below, and the base heat exchanger 43 may be turned on at an outside air humidity of above the predetermined value.

In another example, the opening degree of the flow rate adjusting device 42 may be controlled on the basis of a result of detection by the outside air temperature detecting unit and a result of detection by the outside air humidity detecting unit.

[0050]

The opening degree of the flow rate adjusting device 42 may be controlled so that the lower the temperature detected by the outside air temperature detecting unit, the larger the opening degree of the flow rate adjusting device 42. The opening degree of the flow rate adjusting device 42 may be controlled so that the higher the humidity detected by the outside air humidity detecting unit, the larger the opening degree of the flow rate adjusting device 42.

[0051]

Moreover, after the end of the processing of step S101, a reverse defrosting operation may be performed. Then, the procedure may proceed to step S102. Specifically, after the end of the processing of step S101, the control unit 91 causes the flow switching device 3 to change the direction in which the refrigerant flows so that the cooling operation is performed. Thus, the cooling operation is performed. Then, by guiding the high-temperature, high-pressure refrigerant discharged from the compressor 1 to the heat source side heat exchanger 5, frost on the heat source side heat exchanger 5 melts. The heating operation is performed by causing the flow switching device 3 to change the direction in which the refrigerant flows so that the heating operation is performed. Then, the procedure proceeds to step S102.

Reference Signs List [0052] 1 compressor 2 check valve 3 flow switching device 4 refrigerant pipe 5 heat source side heat exchanger 6 accumulator 10 outdoor unit 10a housing 10a1 bottom surface 10a2 drain hole 11 use side heat exchanger 12 expansion device 20 indoor unit 31 main circuit 41 bypass 42 flow rate adjusting device 43 base heat exchanger 44 opening and closing device 51 branch portion 52 junction portion 91 control unit 100 air-conditioning apparatus

Claims

CLAIMS [Claim 1] An air-conditioning apparatus comprising: a main circuit in which at least a compressor, a use side heat exchanger, an expansion device, and a heat source side heat exchanger are connected sequentially by pipes; a bypass diverging from the main circuit at a branch portion positioned on an outlet side of the compressor and on an inlet side of the use side heat exchanger, and joining the main circuit at a junction portion positioned on an outlet side of the expansion device and on an inlet side of the heat source side heat exchanger; a flow rate adjusting device provided in the bypass and configured to adjust an amount of refrigerant flowing through the bypass; a housing accommodating the heat source side heat exchanger; a base heat exchanger provided in the bypass and on a bottom surface of the housing; and a control unit configured to control an opening degree of the flow rate adjusting device, the bottom surface of the housing being provided with an opening. [Claim 2] The air-conditioning apparatus of claim 1 further comprising a heat source side air sending unit configured to supply outside air to the heat source side heat exchanger, and generate an air flow, wherein in plan view of inside of the housing, the base heat exchanger is provided on a downstream side of an opening edge of the opening closest to the heat source side heat exchanger, the downstream side being a downstream side of the airflow. [Claim 3] The air-conditioning apparatus of claim 1 or 2 further comprising a physical value detecting unit configured to detect a physical value relating to outside air, wherein the control unit is configured to control the opening degree of the flow rate adjusting device based on a result of detection by the physical value detecting unit. [Claim 4] The air-conditioning apparatus of claim 3, wherein the physical value detecting unit includes an outside air temperature detecting unit that is configured to detect a temperature of the outside air, and the control unit is configured to control the opening degree of the flow rate adjusting device so that the lower the temperature detected by the outside air temperature detecting unit, the larger the opening degree of the flow rate adjusting device. [Claim 5] The air-conditioning apparatus of claim 3, wherein the physical value detecting unit includes an outside air humidity detecting unit that is configured to detect humidity of the outside air, and the control unit is configured to control the opening degree of the flow rate adjusting device so that the higher the humidity detected by the outside air humidity detecting unit, the larger the opening degree of the flow rate adjusting device. [Claim 6] The air-conditioning apparatus of claim 3, wherein the physical value detecting unit includes an outside air temperature detecting unit that is configured to detect a temperature of the outside air and an outside air humidity detecting unit that is configured to detect humidity of the outside air, and the control unit is configured to control the opening degree of the flow rate adjusting device based on a result of detection by the outside air temperature detecting unit and a result of detection by the outside air humidity detecting unit. [Claim 7] The air-conditioning apparatus of any one of claims 1 to 6, wherein the base heat exchanger is U-shaped. [Claim 8] The air-conditioning apparatus of any one of claims 1 to 7, wherein a plurality of openings each of which is the opening are provided.