EP1983270A1

EP1983270A1 - Air conditioner

Info

Publication number: EP1983270A1
Application number: EP07713779A
Authority: EP
Inventors: Shun Yoshioka; Naoyuki Ohta
Original assignee: Daikin Industries Ltd
Current assignee: Daikin Industries Ltd
Priority date: 2006-02-03
Filing date: 2007-02-02
Publication date: 2008-10-22
Also published as: KR20080083356A; AU2007210492B2; CN101375108B; CN101375108A; JP2007205661A; JP4495090B2; WO2007088964A1; EP1983270A4; AU2007210492A1; KR100981246B1

Abstract

A bottommost refrigerant path among a plurality of refrigerant paths provided in an indoor heat exchanger (5) is configured such that, in cooling operation, a refrigerant flows through heat transfer tubes (6) positioned on the upwind side and the downwind side of the indoor heat exchanger (5) in relation to air blown from an air blower (21) and the refrigerant exits from a heat transfer tube (6) which is positioned at the second bottommost level or a higher level and on the upwind side of the indoor heat exchanger (5).

Description

TECHNICAL FIELD

The present invention relates to an air conditioning system which restrains uneven flow of a refrigerant in a heat exchanger.

BACKGROUND ART

According to a recent trend toward energy conservation, a heat exchanger of a high-power air conditioning system requires multiple refrigerant paths, each of which consists of a single serpentine heat transfer tube, for the purpose of avoiding decrease in performance of the system caused by pressure loss in an evaporator.
When the number of the refrigerant paths is increased, it is necessary to reduce the difference in amount of heat exchange among the refrigerant paths derived from the difference in wind speed distribution such that indoor air sucked in the system is surely guided to an indoor heat exchanger without leakage. For this reason, the bottom end of the heat exchanger is directly placed on the bottom of a drain pan (cf. Patent Literature 1).
Hereinafter, a conventional configuration of the refrigerant paths is explained with reference to FIGS. 4 to 6 . In FIGS. 4 to 6 , an indoor heat exchanger (5) is used as an evaporator.
Among the refrigerant paths shown in FIG. 4 , a bottommost refrigerant path is configured such that the refrigerant flows into a second bottommost heat transfer tube (6) on the downwind side of the heat exchanger, passes through a second bottommost heat transfer tube (6) on the upwind side and a bottommost heat transfer tube (6) on the downwind side in this order, and then exits from a bottommost heat transfer tube (6) on the upwind side.
The bottommost refrigerant path shown in FIG. 5 is configured such that the refrigerant flows into the bottommost heat transfer tube (6) on the upwind side, passes through the second bottommost heat transfer tube (6) on the upwind side and the second bottommost heat transfer tube (6) on the downwind side in this order, and then exits from the bottommost heat transfer tube (6) on the downwind side.
The bottommost refrigerant path shown in FIG. 6 is configured such that the refrigerant flows into the bottommost heat transfer tube (6) on the upwind side, passes through the second bottommost heat transfer tube (6) on the upwind side and the bottommost heat transfer tube (6) on the downwind side in this order, and then exits from the second bottommost heat transfer tube (6) on the downwind side.

[Patent Literature 1] Japanese Unexamined Patent Publication No. 2005-315455

DISCLOSURE OF INVENTION

PROBLEM THAT THE INVENTION IS TO SOLVE

When the refrigerant path is configured as shown in FIG. 4 and the indoor heat exchanger (5) is used as an evaporator, condensate water generated in the indoor heat exchanger (5) is retained in a drain pan (22). As a result, the heat transfer tube (6) of the bottommost refrigerant path of the indoor heat exchanger (5) from which the refrigerant exits is submerged in the condensate water. Accordingly, part of the capacity of the heat exchanger is used for the heat exchange with the condensate water. This brings about extreme decrease in heat exchange capacity on the refrigerant exit side.
In the refrigerant paths configured as shown in FIG. 5 and FIG. 6 , the heat transfer tube (6) of the refrigerant path from which the refrigerant exits is positioned on the downwind side of the indoor heat exchanger (5). Therefore, heat exchange efficiency of the indoor heat exchanger (5) is reduced.
The present invention has been achieved with the foregoing in mind. An object of the invention is to provide an air conditioning system capable of restraining uneven flow of the refrigerant in the heat exchanger and offering excellent cooling capacity and heat exchange efficiency.

MEANS OF SOLVING THE PROBLEM

According to the present invention, in order to prevent the submersion of the heat transfer tube (6) of the bottommost refrigerant path from which the refrigerant exits, the heat transfer tube (6) from which the refrigerant exits is positioned at the second bottommost level or a higher level and on the upwind side of the heat exchanger.
In a first aspect, the present invention is directed to an air conditioning system including a heat exchanger (5) having a plurality of refrigerant paths, each of which is formed of a plurality of heat transfer tubes (6) arranged at predetermined intervals; an air blower (21) which blows indoor air to the heat exchanger (5) for heat exchange; and a drain pan (22) which retains condensate water generated in the heat exchanger (5).
A bottommost refrigerant path among the plurality of refrigerant paths is configured such that, in cooling operation, a refrigerant flows through the heat transfer tubes (6) positioned on the upwind side and the downwind side of the heat exchanger (5) in relation to the air blown from the air blower (21) and the refrigerant exits from the heat transfer tube (6) which is positioned at the second bottommost level or a higher level and on the upwind side of the heat exchanger (5).
According to the first aspect of the invention, the bottommost refrigerant path is configured such that, in cooling operation, the refrigerant flows through the heat transfer tubes (6) positioned on the upwind side and the downwind side of the heat exchanger (5) and the refrigerant exits from the heat transfer tube (6) which is positioned at the second bottommost level or a higher level and on the upwind side of the heat exchanger (5).
As a result, the number of curves of the heat transfer tubes (6) is increased to enhance the heat exchange capacity of the bottommost refrigerant path of the heat exchanger (5). This is advantageous from the aspect of restraining the decrease in evaporation capacity of the heat exchanger (5). Further, since the heat transfer tube (6) from which the refrigerant exits is positioned at the second bottommost level or a higher level and on the upwind side of the heat exchanger (5), decrease in heat exchange efficiency derived from the condensate water retained in the drain pan (22) is minimized.
According to a second aspect of the invention related to the first aspect of the invention, the air conditioning system further includes a drain pump (23) for draining the condensate water retained in the drain pan (22). The drain pump (23) is configured to drain the condensate water before the level of the condensate water retained in the drain pan (22) comes up to the level of the heat transfer tube (6) from which the refrigerant exits.
According to the second aspect of the invention, the condensate water is drained before the level of the condensate water retained in the drain pan (22) comes up to the level of the heat transfer tube (6) from which the refrigerant exits. Therefore, the heat transfer tube (6) of the refrigerant path from which the refrigerant exits is not submerged in the condensate water. As a result, the capacity of the heat exchanger is prevented from being partially used for the heat exchange with the condensate water and the decrease in heat exchange efficiency is restrained.
According to a third aspect of the invention related to the first aspect of the invention, the air conditioning system further includes a drain pump (23) for draining the condensate water retained in the drain pan (22) and a water level detector (24) for detecting that the level of the condensate water retained in the drain pan (22) has come up to a predetermined level lower than the level of the heat transfer tube (6) from which the refrigerant exits. The drain pump (23) is configured to drain the condensate water based on the detection result of the water level detector (24).
According to the third aspect of the invention, the water level detector (24) detects that the level of the condensate water retained in the drain pan (22) has come up to a predetermined level lower than the level of the heat transfer tube (6) from which the refrigerant exits and the drain pump (23) drains the condensate water based on the detection result of the water level detector (24). Therefore, the drain pump (23), which has conventionally been driven at all time for preventing the submersion of the refrigerant path irrespective of the level of the condensate water, is driven intermittently depending on the level of the condensate water. This makes it possible to reduce energy consumption.

EFFECT OF THE INVENTION

According to the present invention described above, the number of curves of the heat transfer tubes (6) is increased to enhance the heat exchange capacity of the bottommost refrigerant path of the heat exchanger (5). This is advantageous from the aspect of restraining the decrease in evaporation capacity of the heat exchanger (5). Further, since the heat transfer tube (6) from which the refrigerant exits is positioned at the second bottommost level or a higher level and on the upwind side of the heat exchanger (5), decrease in heat exchange efficiency derived from the condensate water retained in the drain pan (22) is minimized.
According to the second aspect of the invention, the heat transfer tube (6) of the refrigerant path from which the refrigerant exits is not submerged in the condensate water. Therefore, the capacity of the heat exchanger is prevented from being partially used for the heat exchange with the condensate water and the decrease in heat exchange efficiency is restrained.
According to the third aspect of the invention, the drain pump (23), which has conventionally been driven at all time for preventing the submersion of the refrigerant path irrespective of the level of the condensate water, is driven intermittently depending on the level of the condensate water. This makes it possible to reduce energy consumption.

BRIEF DESCRIPTION OF DRAWINGS

[FIG. 1]
FIGS. 1A and 1B are diagrams of a refrigerant circuit in an air conditioning system according to an embodiment of the present invention.
[FIG. 2 ]
FIG. 2 is a schematic view illustrating the internal configuration of an indoor unit of the air conditioning system according to the embodiment.
[FIG. 3 ]
FIG. 3 is a side view illustrating the configuration of refrigerant paths of an indoor heat exchanger according to the embodiment.
[FIG. 4 ]
FIG. 4 is a schematic view illustrating the internal configuration of an example of an indoor unit of a conventional air conditioning system.
[FIG. 5 ]
FIG. 5 is a schematic view illustrating the internal configuration of another example of the indoor unit of the conventional air conditioning system.
[FIG. 6 ]
FIG. 6 is a schematic view illustrating the internal configuration of still another example of the indoor unit of the conventional air conditioning system.

EXPLANATION OF REFERENCE NUMERALS

5: Indoor heat exchanger (heat exchanger)
6: Heat transfer tube
21: Air blower
22: Drain pan
23: Drain pump
24: Float switch (water level detector)

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of the present invention is described in detail with reference to the drawings. The description of the preferred embodiment is provided only for explanation purpose and does not limit the present invention, an object to which the present invention is applied and use of the invention.
FIGS. 1A and 1B are diagrams of a refrigerant circuit in an air conditioning system according to the embodiment of the present invention. As shown in FIG. 1 , a refrigerant circuit (1) is a closed circuit including a compressor (7) as a compression mechanism, a four-way switching valve (9) as a refrigerant controller, an outdoor heat exchanger (3), an expansion valve (11) as an expansion mechanism and an indoor heat exchanger (5) connected in this order. The refrigerant circuit (1) is filled with a refrigerant such that the refrigerant circulates therein to perform vapor compression refrigeration cycles. The four-way switching valve (9) has first to fourth ports (9a, 9b, 9c and 9d) to which pipes of the refrigerant circuit (1) are connected.
A diverting device (13) and a merging device (15) are connected to the indoor heat exchanger (5). In cooling operation, the diverting device (13) reduces the pressure of the refrigerant condensed in the outdoor heat exchanger (3) and distributes the refrigerant to the refrigerant paths of the indoor heat exchanger (5). The merging device (15) combines the refrigerants evaporated in the refrigerant paths of the indoor heat exchanger (5) and sends the combined refrigerant to the outdoor heat exchanger (3).
In the refrigerant circuit (1), a discharge port of the compressor (7) is connected to the first port (9a) of the four-way switching valve (9). The third port (9c) of the four-way switching valve (9) is connected to an end of the outdoor heat exchanger (3). The other end of the outdoor heat exchanger (3) is connected to an end of the indoor heat exchanger (5) through the expansion valve (11). The other end of the indoor heat exchanger (5) is connected to the fourth port (9d) of the four-way switching valve (9). The second port (9b) of the four-way switching valve (9) is connected to a suction port of the compressor (7).
The four-way switching valve (9) is switchable between a state in which the first port (9a) and the third port (9c) communicate with each other and the second port (9b) and the fourth port (9d) communicate with each other simultaneously (a state shown in FIG. 1A ) and a state in which the first port (9a) and the fourth port (9d) communicate with each other and the second port (9b) and the third port (9c) communicate with each other simultaneously (a state shown in FIG. 1B ).
Specifically, the four-way switching valve (9) is able to switch the circulating direction of the refrigerant in the refrigerant circuit (1). As a result, the state of the circuit is switched between the state in which the refrigerant in the outdoor heat exchanger (3) is condensed and the refrigerant in the indoor heat exchanger (5) is evaporated simultaneously and the state in which the refrigerant in the outdoor heat exchanger (3) is evaporated and the refrigerant in the indoor heat exchanger (5) is condensed simultaneously.
FIG. 2 is a schematic view illustrating the internal configuration of an indoor unit of the air conditioning system of the present embodiment. Referring to FIG. 2 , the indoor unit includes an indoor heat exchanger (5), an air blower (21) which blows the indoor air to the indoor heat exchanger (5) for heat exchange, a drain pan (22) which retains condensate water generated in the indoor heat exchanger (5) and on which the indoor heat exchanger (5) is placed, a drain pump (23) which drains the condensate water retained in the drain pan (22) and a float switch (24) as a water level detector which detects that the level of the condensate water retained in the drain pan (22) has come up to a predetermined level.
The indoor heat exchanger (5) has a plurality of refrigerant paths, each of which is formed of a plurality of heat transfer tubes (6) arranged at predetermined intervals. To be more specific, in the present embodiment, 24 heat transfer tubes (6) are used. The ends of the heat transfer tubes (6) are connected with U-shaped pipes to provide 11 refrigerant paths (see FIG. 3 ). In FIGS. 2 and 3 , the refrigerant circulating direction in the cooling operation is indicated by arrows.
The refrigerant distributed by the diverting device (13) flows into each of the refrigerant paths. The refrigerants exit from the refrigerant paths are combined by the merging device (15) and then the combined refrigerant flows into the outdoor heat exchanger (3).
The plurality of refrigerant paths are configured in the same manner except the bottommost refrigerant path. To be more specific, the bottommost refrigerant path consists of four heat transfer tubes (6). The refrigerant flows into the bottommost heat transfer tube (6) on the upwind side of the indoor heat exchanger (5), passes through the bottommost heat transfer tube (6) on the downwind side and the second bottommost heat transfer tube (6) on the downwind side in this order, and then exits from the second bottommost heat transfer tube (6) on the upwind side.
Each of the refrigerant paths other than the bottommost refrigerant path consists of two heat transfer tubes (6). The refrigerant flows into the heat transfer tube (6) on the upwind side and then exits from the heat transfer tube (6) on the downwind side.
For the heating operation, the refrigerant is circulated in the reverse direction in the refrigerant paths of the indoor heat exchanger (5). Specifically, in the bottommost refrigerant path, the refrigerant flows into the second bottommost heat transfer tube (6) on the upwind side of the indoor heat exchanger (5), passes through the second bottommost heat transfer tube (6) on the downwind side and the bottommost heat transfer tube (6) on the downwind side in this order, and then exits from the bottommost heat transfer tube (6) on the upwind side.
In each the refrigerant paths other than the bottommost refrigerant path, the refrigerant flows into the heat transfer tube (6) on the downwind side and then exits from the heat transfer tube (6) on the upwind side.
The float switch (24) is configured to detect that the level of the condensate water retained in the drain pan (22) has come up to a predetermined level lower than the level of the heat transfer tube (6) from which the refrigerant exits. To be more specific, the predetermined level is lower than the position of the second bottommost heat transfer tube (6) on the upwind side of the indoor heat exchanger (5).
The drain pump (23) is configured to drain the condensate water in the drain pan (22) based on the detection result of the float switch (24). This is advantageous from the aspect of preventing the submersion of the heat transfer tube (6) of the bottommost refrigerant path from which the refrigerant exits and ensuring the heat exchange efficiency.
According to the air conditioning system of the present invention, the number of curves of the heat transfer tubes (6) is increased to enhance the heat exchange capacity of the bottommost refrigerant path of the heat exchanger (5). This is advantageous from the aspect of restraining the decrease in evaporation capacity of the heat exchanger (5). Further, since the heat transfer tube (6) from which the refrigerant exits is positioned at the second bottommost level and on the upwind side of the heat exchanger (5), the decrease in heat exchange efficiency derived from the condensate water retained in the drain pan (22) is minimized.
The condensate water is drained before the level of the condensate water retained in the drain pan (22) comes up to the level of the heat transfer tube (6) from which the refrigerant exits. Therefore, the heat transfer tube (6) of the refrigerant path from which the refrigerant exits is not submerged in the condensate water. As a result, the capacity of the heat exchanger is prevented from being partially used for the heat exchange with the condensate water and the decrease in heat exchange efficiency is restrained.
The float switch (24) detects that the level of the condensate water retained in the drain pan (22) has come up to the predetermined level lower than the level of the heat transfer tube (6) from which the refrigerant exits and the drain pump (23) drains the condensate water based on the detection result. Therefore, the drain pump (23), which has conventionally been driven at all time for preventing the submersion of the refrigerant path irrespective of the level of the condensate water, is driven intermittently depending on the level of the condensate water. This makes it possible to reduce energy consumption.

INDUSTRIAL APPLICABILITY

As described above, the present invention is useful for minimizing the decrease in heat exchange efficiency derived from the condensate water generated in the cooling operation.

Claims

An air conditioning system comprising:
a heat exchanger (5) having a plurality of refrigerant paths, each of which is formed of a plurality of heat transfer tubes (6) arranged at predetermined intervals;

an air blower (21) which blows indoor air to the heat exchanger (5) for heat exchange; and

a drain pan (22) which retains condensate water generated in the heat exchanger (5), wherein

a bottommost refrigerant path among the plurality of refrigerant paths is configured such that, in cooling operation, a refrigerant flows through the heat transfer tubes (6) positioned on the upwind side and the downwind side of the heat exchanger (5) in relation to the air blown from the air blower (21) and the refrigerant exits from the heat transfer tube (6) which is positioned at the second bottommost level or a higher level and on the upwind side of the heat exchanger (5).
The air conditioning system of Claim 1, further comprising a drain pump (23) for draining the condensate water retained in the drain pan (22), wherein
the drain pump (23) is configured to drain the condensate water before the level of the condensate water retained in the drain pan (22) comes up to the level of the heat transfer tube (6) from which the refrigerant exits.
The air conditioning system of Claim 1, further comprising a drain pump (23) for draining the condensate water retained in the drain pan (22) and a water level detector (24) for detecting that the level of the condensate water retained in the drain pan (22) has come up to a predetermined level lower than the level of the heat transfer tube (6) from which the refrigerant exits, wherein
the drain pump (23) is configured to drain the condensate water based on the detection result of the water level detector (24).