WO2024047836A1

WO2024047836A1 - Air-conditioning apparatus and casing structure

Info

Publication number: WO2024047836A1
Application number: PCT/JP2022/032931
Authority: WO
Inventors: Manish Kumar; Vinay Shrivastava; Rohan Shah; Taku Iwase; Hideshi Obara
Original assignee: Hitachi-Johnson Controls Air Conditioning, Inc.
Priority date: 2022-09-01
Filing date: 2022-09-01
Publication date: 2024-03-07

Abstract

[Problem to be Solved] To provide air-conditioner and casing structure. [Means for Solving Problem] An air-conditioner of the present invention comprises heat exchanger, a fan unit, non-azeotropic refrigerant conducting heat exchange with the heat exchanger, and a casing enclosing at least the heat exchanger and a fan unit. The air-conditioning apparatus further comprises a fan unit comprising a propeller fan, the propeller fan rotating in a positive direction and a reverse direction depending on operating modes of the air-conditioning apparatus; and a fan motor for rotating the propeller fan in the positive direction and in the reverse direction to achieve a counter-flow heat exchange condition regardless of the operating modes, wherein the propeller fan includes a plurality of fan blades having a symmetrical shape with respect to a symmetry axis passing a center of the propeller fan. The air-conditioning apparatus further comprises a wind guides and crosspieces at the lateral side in order to eliminate short-cycling and enhance airflow performance respectively.

Description

AIR-CONDITIONING APPARATUS AND CASING STRUCTURE

Field of Invention

The present invention relates generally to an air-conditioning technology, and more particularly relates to an air-conditioning apparatus and a casing structure for improving performance of an air-conditioner.

Background of Invention

To reduce global warming potential usage of non-azeotropic refrigerant that may attain extremely low Global Warming Potential (hereafter referred to GWP) becomes consideration in place of refrigerant such as R32. However, because of temperature glide and high-specific volume of non-azeotropic refrigerant as compared to R32, cooling/heating capacity and efficiency would become reduced.

In the case where a heat exchanger of an outdoor unit (hereafter referred to ODU) is operated in conventional constant airflow direction in cooling & heating mode, flow directions of the refrigerant are reversed in heating mode, a parallel-flow heat exchanger condition will occur in heating mode. In this regard, the efficiency of the non-azeotropic refrigerant may become even worse due to generation of the parallel-flow condition in heat exchanger operation.

Fig. 28 shows a sample refrigerant-flow directions for explain the counter-flow and the parallel-flow occurring in a heat exchanger of the ODU in heating mode. In Fig. 28, the lower temperature refrigerant is illustrated by lighter gray lines and the higher temperature refrigerant is illustrated by deeper gray (black) lines.

Fig. 28(a) & Fig. 28(b) shows outdoor heat exchanger operation in heating mode with counterflow & parallel flow type arrangement respectively. The heat exchanger 2802 conducts heat exchange between an airflow 2801 drawn into the ODU (not shown) and refrigerant 2804 flowing through heat exchanger 2802 tubes.

In Fig. 28(a), the airflow 2801 drawn into the heat exchanger 2802 conducts the heat exchange with the refrigerant flow 2804 in a counter-flow where the drawn airflow 2801 first conducts the heat exchange with the high temperature refrigerant 2804. As well-known in the art, heat exchange efficiencies become higher and higher as temperature difference become larger and larger such that the heat exchange between the airflow 2801 and the refrigerant conducts high-efficiency heat exchange.

This condition will change in the parallel mode shown in Fig. 28(b) where a refrigerant flow direction reverses and the airflow drawn into the ODU (not shown) first conducts the heat exchange with the low temperature refrigerant 2804 such that the heat exchange efficiencies become lower. Even though this may be acceptable, but not optimal, with a heat exchange scheme in the case where the refrigerant is of one kind or of azeotropic (or pseudo-azeotropic). However, in the case where the refrigerant is of non-azeotropic, the air-conditioning efficiencies of the air-conditioning apparatus significantly lowered due to the parallel-flow, its temperature glide, and the high-specific volume.

Although it may be possible to keep a counter-flow arrangement between a refrigerant direction and an airflow direction during both in the heating and cooling modes using the non-azeotropic refrigerant, such design efforts may require large structural changes of air-conditioning designs and will require large costs.

Since the coolant air for the heat exchanger in the ODU is supplied normally by a propeller fan, if the propeller fan is rotated reversely in heating mode, the reverse airflow direction might be provided such that the counter-flow heat exchange scheme can be attained as shown in Fig. 28(a).

However, such reverse rotation of the propeller fan may increase power consumption of the propeller fan as well as decrease in airflow performances, because a conventional propeller fan has typically a concave surface 2902 facing to the rotational direction and also has a convex surface 2901 facing opposite to the rotational direction as shown in Fig. 29 (a). The conventional propeller fan for an air-conditioning apparatus further comprises a sharp blade tip at leading edge under the premise that the propeller fan would rotate in a predetermined direction in its normal usage. Also, the conventional bell-mouth shape is unsymmetrical in shape & has been optimally design for unidirectional flow as shown in Fig. 29 (b). This means that conventional propeller fans have not been designed as a bidirectional rotation in its practical usage.

In addition, such reverse operation of the propeller fan causes another problem that when the the propeller fan rotates reversely against to its premised rotational direction, air-short cycling may become increased in an ODU, which can also deteriorate the heat exchanger performance. Hence, this short cycling should be addressed by providing structures with compatible performances.

Many efforts have been made for improving performance of propeller fans, and for example, JPH08-285397 (Patent Literature 1) discloses an invention that can change flow direction in case of cooling and heating operations in air-conditioner using a non-azeotropic mixed refrigerant. Its blades are formed by a movable shape-memory material, and when changing the flow direction, a blade camber changes for flowing the airflow from grill to heat exchanger.

WO2021192237 (PCT／JP2020／014075) (Patent Literature 2) discloses a wind direction guide, which can make the direction of air blown from an outdoor unit change. The wind direction guide is attached to a front panel of an outdoor unit after a grille, and this wind direction guide is consisting of wind guide plates for changing the direction of exhaust air.

JP2002-229691 (Patent Literature 3) also discloses a wind-direction guide and an outdoor unit for controlling a direction of blowen-out air from the ODU. However, JP2002-229691 solely makes a direction of exhausted air change optionally rather than reducing the short cycling.

Thus, a novel technology has been still needed for using non-azeotropic refrigerant while improving air-conditioning performance without changing large design change of an air-conditioning apparatus.

[Patent Literature 1] JPH08-285397
[Patent Literature 2] WO2021192237
[Patent Literature 3] JP2002-229691

Problem to be Solved by Invention

The present invention has been completed considering above problems of conventional technologies, and an object of the present invention is to provide a novel air-conditioning apparatus suitably used for non-azeotropic refrigerant.

Means for Solving Problem

According to one or more embodiment of the present invention, an air-conditioning apparatus and a casing structure may be provided. The air conditioning apparatus comprises a heat exchanger, a fan unit, refrigerant conducting heat exchange with the heat exchanger, and a casing enclosing at least the heat exchanger and a fan unit, the air-conditioning apparatus comprising: a fan unit comprising a propeller fan, the propeller fan rotating in a positive direction and a reverse direction depending on operating modes of the air-conditioning apparatus; and a fan motor for rotating the propeller fan in the positive direction and in the reverse direction to achieve a counter-flow heat exchange condition regardless of the operating modes, wherein the propeller fan includes a plurality of fan blades having a symmetrical shape with respect to a symmetry axis passing a center of the propeller fan and a positive rotation generates an airflow in a direction from the heat exchanger to a fan unit, and a reverse rotation generates another air flow in a direction from the fan unit to the heat exchanger depending on the operating modes of the air-conditioning apparatus and wherein the propeller fan includes a plurality of fan blades having a symmetrical shape with respect to a symmetry line B passing a center of the propeller fan.

According to one more embodiment of the present invention, the refrigerant is non-azeotropic refrigerant.

According to one or more embodiment of the present invention, the outdoor unit uses a non-azeotropic refrigerant that has temperature glide more than 3 degrees.

According to one or more embodiment of the present invention, the air-conditioning apparatus further comprises a bell mouth having a flat region facing to the fan blade and extending to a direction of the airflow while surrounding the propeller fan, and a center of an outer periphery of the fan blade is positioned in a level within the flat region facing to the fan blade.

According to one or more embodiment of the present invention, the center of the outer periphery of the fan blade is positioned at a center of the flat region of the bell mouth or is shifted toward the heat exchanger from the center of the flat region.

According to another aspect of the present invention, a casing for an air-conditioning apparatus may be provided. The casing structure comprises a wind guide integrally disposed to a lateral side of the air-conditioning apparatus and the wind guide allows an airflow discharged from the lateral side to exit distally from a front side of the air-conditioning apparatus which may prevent short-cycling in reverse rotation of propeller fan, wherein the air-conditioning apparatus comprises a heat exchanger, a fan unit, non-azeotropic refrigerant conducting heat exchange with the heat exchanger, and the casing enclosing the heat exchanger and the air-conditioning apparatus further comprises a fan unit comprising a propeller fan, the propeller fan rotating in a positive direction and a reverse direction depending on operating modes of the air-conditioning apparatus; and a fan motor for rotating the propeller fan in the positive direction and in the reverse direction to achieve a counter-flow heat exchange condition regardless of the operating modes, wherein the propeller fan includes a plurality of fan blades having a symmetrical shape with respect to a symmetry axis passing a center of the propeller fan.

According to one or more embodiment of the present invention, the wind guide has an aperture or apertures positioned distally from the front side of the air-conditioning apparatus.

According to one or more embodiment of the present invention, the wind guide has inclined apertures or forms inclined apertures to a back side of the air-conditioning apparatus.

According to one or more embodiment of the present invention, the casing comprises a plurality of slots at the lateral side of the casing, and the plurality of slots is configured by crosspieces having almost a triangle rectangular cross-section with facing its top to towards the heat exchanger.

Advantageous Effect of Invention

According to the present invention, an air-conditioning apparatus and a casing structure suitably used to non-azeotropic refrigerant can be provided, which can provide excellent air flows to forward and reverse directions, acceptable static pressure rise, efficiency, and noise suppression.

[Fig. 1]Fig. 1 shows generally an exemplary embodiment of an air-conditioning apparatus 100 according to one embodiment of the present invention.
[Fig. 2]Fig. 2 shows a detailed structure of an ODU 101 according to one embodiment of the present invention.
[Fig. 3]Fig. 3 shows a partial cross-sectional view of an ODU 101 through a line A-A of Fig. 2.
[Fig. 4]Fig. 4 shows a novel structure of the propeller fan 102 according to one embodiments of the present invention together with a sample conventional fan blade 400.
[Fig. 5]Fig. 5 shows a detailed side view of the propeller fan 102 according to one embodiment according to the present invention.
[Fig. 6]Fig. 6 shows an alternative embodiment where the position of the propeller fan 102, i.e., fan blades 102-1, 102-2, and 102-3 is shifted to a HEX 125 according to on or more embodiment of the present invention.
[Fig. 7]Fig. 7 shows air-conditioning performances according to one or more embodiment of the present invention in a form of a table.
[Fig. 8]Fig. 8 shows air-conditioning performances according to one or more embodiment of the present invention in a form of a table.
[Fig. 9]Fig. 9 shows air-conditioning performances according to one or more embodiment of the present invention in a form of a table.
[Fig. 10A]Fig. 10A shows a plot of results of a cycle simulation of the air-conditioning apparatus according to one or more embodiments of the present invention in the heating mode.
[Fig. 10B]Fig. 10B shows parameters in the simulation for Examples and the comparative example and the simulated APF values as well as the simulated APF values.
[Fig. 11]Fig. 11 shows a result of a CFD (Computational Fluid Dynamics) calculation of the airflow around an ODU 101A (equipping conventional propeller fan 400) and an ODU 101 (equipping present propeller fan 102) in the reverse rotation operation according to one or more embodiment of the present invention.
[Fig. 12]Fig. 12 shows one embodiment of a wind guide 1201 and an ODU 101 to which the wind guide 1201 is attached.
[Fig. 13]Fig. 13 shows a CFD simulation illustrating the effect of a wind guide 1201 of one embodiment according to the present invention.
[Fig. 14]Fig. 14 shows another embodiment of a wind guide 1401 of one or more embodiments according to the present invention.
[Fig. 15]Fig. 15 shows an effect of the wind guide 1401 of Fig. 14 simulated by CFD according to the present invention.
[Fig. 16]Fig. 16 shows another embodiment of a wind guide 1601 according to one or more embodiments according to the present invention.
[Fig. 17]Fig. 17 shows an effect of the wind guide of Fig. 16 simulated by CFD according to the present invention.
[Fig. 18]Fig. 18 shows still another embodiment of the wind guide 1801 of one or more embodiment according to the present invention.
[Fig. 19]Fig. 19 shows an effect of the wind guide 1801 of Fig. 18 simulated by CFD according to the present invention.
[Fig. 20]Fig. 20 shows still further another embodiment of the wind guide 2001 of one or more embodiment according to the present invention.
[Fig. 21]Fig. 21 shows an effect of the wind guide 2001 of Fig. 20 simulated by CFD according to the present invention.
[Fig. 22A]Fig. 22A shows further another embodiment for performance enhancement of one or more embodiment according to the present invention.
[Fig. 22B]Fig. 22B shows an enlarged shape of crosspieces 2203 forming at the lateral slots of a casing.
[Fig. 23]Fig. 23 shows an effect of crosspieces shapes on airflow performance of one or more embodiment according to the present invention.
[Fig. 24]Fig. 24 shows a CFD calculation for an effect of crosspiece shapes on velocity distribution of one or more embodiment according to the present invention.
[Fig. 25]Fig. 25 shows a CFD calculation for effect of crosspiece shapes on velocity distribution of one or more embodiment according to the present invention.
[Fig. 26]Fig. 26 shows a CFD calculation for effect of crosspiece shapes on velocity distribution of one or more embodiment according to the present invention.
[Fig. 27]Fig. 27 shows a CFD calculation for effect of crosspiece shapes on velocity distribution of one or more embodiment according to the present invention.
[Fig. 28]Fig. 28 shows a sample refrigerant-flow directions for explain the counter-flow and the parallel-flow occurring in heating mode in a heat exchanger of the ODU.
[Fig. 29]Fig. 29 shows a conventional shape of propeller fan and a relative position between fan blade and a bell mouth.

Embodiment for Practicing Invention

General Configuration of Air-Conditioning Apparatus
Now, one or more embodiments will be described with referring to drawings which should be used for solely understanding the present invention. Drawings and following detailed description should not be understood to limit any how the present invention recited in appended claims. It should be understood that well-known elements and elements having relatively low importance in the description of drawings are not described in drawings for clearness of the description as well as understanding an essential principle of the present invention. However, such omission of the elements in descriptions should not imply that such elements are not used in the present invention. Hereafter, similar elements are referred by similar numeral and signs until otherwise stated.

Fig. 1 generally shows an exemplary embodiment of an air-conditioning apparatus 100 according to one or more embodiment of the present invention. Types of the air-conditioning apparatus 100 of one or more embodiment is not limited particularly, and may be implemented as a package air-conditioning apparatus (PAC), a room air-conditioning apparatus (RAC), a multiple air-conditioning apparatus such as a variable refrigerant flow (VRF) system or a refrigerator depending on particular applications.

The air-conditioning apparatus 100 includes an indoor unit (IDU) 110, an outdoor unit (hereafter referred to ODU) 101, and a refrigerant piping 140 connecting between the indoor unit 110 and the ODU 101 The indoor unit 110 is placed in indoor space where the air-conditioning is performed and provides the air-conditioning desired by users through a remote-controlled peripheral such as a remote controller 140 operated by a user.

The indoor unit 110 encloses a filter 113, a fan 114, and an indoor heat-exchanger (not shown), and the suction grill 112 is placed from the front to the top facing to the indoor space. The indoor unit 110 supplies the air for air-conditioning from a blow-out grill 115 into the indoor space and draws the indoor-air through the suction grill 112 into the indoor unit 110 for making it possible to perform the air-conditioning of the indoor-air.

In addition, the ODU 101 encloses at least a compressor 126, a heat-exchanger (HEX) 125, and a fan unit comprising a propeller fan 102 and a fan motor (not shown) in a casing 108. The propeller fan 102 comprises a hub 103 and a plurality of fan blades 102-1, 102-2, and 102-3 extending radially outwardly from the hub 103; however, number of the propeller fan blades may not be limited to three and other number of blades may be allowed according to one or more embodiment of the present invention.

The compressor 126 compresses the refrigerant returned from the indoor unit 110 after the air-conditioning of the indoor-air and sends it to the heat-exchanger 125 for adjusting the thermodynamic state of refrigerant so that it can provide the air-conditioning continuously in cooling mode The compressor 126 compresses the refrigerant returned from the outdoor heat exchanger 125 and sends it to the indoor unit 110 for adjusting thermodynamic state of refrigerant so that it can provide the air-conditioning continuously in heating mode. The propeller fan 102 is driven by the fan motor (not shown) and draws the outside-air into the ODU 101 from lateral slot and back side opening in positive rotation for cooling mode. The propeller fan 102 is driven by the fan motor (not shown) and draws the outside-air into the ODU 101 from a grill structure 107 attached on a front side of the ODU in a reverse rotation in heating mode. By this way, the present invention provides an always-counter-flow condition with respect to the HEX 125 and refrigerant regardless to operating modes.

Conventional propeller fans have been designed by optimizing efficiency to one major rotational direction, and then, if the propeller fan is rotated in the reverse direction, the efficiency of the propeller fan will become low. According to the present disclosure, in order to achieve the “always counter-flow configuration” with respect to the refrigerant flow direction due to change in the operation modes, a novel propeller fan structure will be described, which can suitably be used both in positive and reverse rotations without significant impacts on air-conditioning performance.

In the present description, the term “positive direction” refers, to the rotational direction of the propeller fan that causes an airflow from a back side to a front side of the casing 108, and the term “reverse direction” refers to the rotational direction of the propeller fan that causes an airflow from the front side to the back side of the casing 108. In addition, the term “front side” refers in the present description refers a side opposite to the side where the HEX 125 is placed beyond the fan unit, and is the side usually covered by a front panel. Now, the propeller fan of the present invention will be described in detail.

Propeller Fan
Fig. 2 shows a detailed structure of an ODU 101 of one or more embodiment of the present invention. The ODU 101 encloses at least the compressor 126, the HEX 125 and the propeller fan 102. The propeller fan 102 comprises a hub 103, a plurality of blades 102-1, 102-2, and 102-3 extending from the hub 103 radially outwardly. Behind the hub 103, a fan motor (not shown in Fig. 2 (being obscured by the propeller fan 102) is disposed, which is in turn supported by a support member 201 such that the propeller fan 102 and the fan motor are securely placed within the ODU 101.

The propeller fan 102 is circumferentially surrounded by a bell mouth 104 while leaving a certain distance between outer peripheries of the fan blade 102-1, 102-2, and 102-3 of the propeller fan 102 and the bell mouth 104. Furthermore, a back panel opening and a plurality of slots 105 are formed at a lateral side of the casing 108 of the ODU 101 for allowing outside air to flow in/out the ODU 101 for the heat exchange with the HEX 125 when the positive /reverse rotation.

Fig. 3 shows a partial cross-sectional view of the ODU 101 through a line A-A of Fig. 2, which shows further detail of a structure around the propeller fan 102. The ODU 101 comprises the HEX 125, disposed along a back wall of a casing 108 of the ODU 101. The HEX 125 conducts the heat exchange with the airflow from the outside environment with the refrigerant to attain desired air-conditioning. When used together with the non-azeotropic refrigerant, the flow direction of the airflows 203, 204 from an ambient environment will change as shown in Fig. 3 for heating & cooling mode respectively.

The propeller fan 102 is positioned and supported by a support member 201 extending from an upper panel to a bottom panel of the casing 108 of the ODU 101. The fan blades 102-1, 102-2, and 102-3 of the propeller fan 102 extend from an outer surface of the hub 103 radially outwardly adjacent to the bell mouth 104 while leaving a certain distance to the bell mouth 104. In one or more embodiment depicted in Fig. 3, the center of the outer periphery of the fan blade, for example, the fan blade 102-1 is positioned at about vertical center of the bell mouth 104 along to the airflow direction. This configuration may not be necessary and will be changed by considering the efficiencies of the air-conditioning apparatus such as airflow rates and/or power consumption. Detail of the positioning between the bell mouth 104 and the propeller fan 102/fan blades 102-1, 102-2, 102-3 will be discussed later.

In non-azeotropic refrigerants having low GWP such as R454A, R454C, a mixture of R32 50% and R123yf 50%, the temperature glide may become relatively large such that the counter-flow usage is strongly recommended. In this disclosure, the term “temperature glide” means difference in a start temperature and a terminal temperature of evaporation and condensation in a heat exchanger (HEX) due to difference of compositions between a liquid phase and a vapor phase.

When the airflow to the HEX 125 becomes the parallel-flow with respect to the refrigerant flow in the HEX 125, the heat exchange performance of the HEX 125 becomes deteriorated and this may even result in discards of merits using the non-azeotropic refrigerant. This fact raises a requirement for providing “always-counter-flow configuration” between the refrigerant flow in the HEX 125 and the airflow from the outside environment.

Furthermore, in this disclosure, the term “parallel-flow” means that the airflow introduced from the ambient environment contacts first with lower-temperature refrigerant flowing in the HEX 125 for heating mode. Alternatively, the term “counter-flow” means that the airflow introduced from the ambient environment contact first with higher-temperature refrigerant flowing in the HEX 125 for heating mode. Furthermore, the term “always counter-flow” means that the airflow introduced from the ambient environment contacts first with the higher temperature refrigerant in heating mode and the lower temperature refrigerant in cooling mode.

The ODU 101 of one or more embodiments of the present invention can address to the above requirement using a novel propeller fan 102 having a symmetric structure. Now, the propeller fan 102 and the fan blades 102-1, 102-2, and 102-3 of the present invention will be described in detail.

The propeller fan 102 of one or more embodiment of the present invention can change the airflow direction by changing rotational directions of the propeller fan 102. As shown in Fig. 3, the airflow 204 (see Fig. 3) is a positive direction for the heat exchange with the HEX 125 and the airflow 203 (see Fig. 3) is a reversed direction for the heat exchange with the HEX 125.

A conventional structure of a propeller fan (discussed later with referring to Fig. 4) has the sharp blade tip at leading edge as well as the concave face facing to the rotational direction and the convex face facing back to the rotational direction. The sharp blade suppresses noise.

As depicted in Fig. 3, for example, the fan blades 102-1, 102-2, and 102-3 of one or more embodiment of the present invention are fixed to the hub 103 with inclined angles along to the airflow direction, and the rotation of the propeller fan 102 generates the airflow 203 and airflow 204 depending on its rotational direction.

Fig. 4 shows a novel structure of the fan blade 102 according to one or more embodiments of the present invention together with a sample conventional fan blade 400. Fig. 4 (a) depicts a plane view of the propeller fan 102 of one or more embodiments of the present invention, and Fig. 4 (b) depicts a plane view of a conventional propeller fan 400.

Each of the fan blade 102-1, 102-2, and 102-3 has a line symmetry about an imaginary symmetry line B extending from the center of the propeller fan 102 to the center of an outer periphery of each of the fan blades 102-1, 102-2, and 102-3, while the imaginary symmetric line B is shown on the fan blade 102-2 as explanations. The other fan blades 102-1 and 102-3 also have the same structure.

In the conventional fan reverse rotation, the camber will become opposite, and the flow may not stick to the blade surface, due to flow separation the airflow reduces drastically.

Fig. 5 shows a detailed side view of the propeller fan 102 (Fig. 5 (a)), a blade section on circular plane at some radius (Fig. 5(b)), and a relative positioning between the propeller fan 102 and the bell mouth 104 (Fig. 5 (c)). The fan blade 102-2 is best depicted for showing its side structure, however, the other fan blades 102-1, 102-3 also have similar shapes and configurations, respectively.

Particularly, Fig. 5 (c), shows the detailed relative positioning between the fan blade 102-2 and the bell mouth 104. In one embodiment, the circumferential center of the outer periphery 102f of the fan blade 102-2 can be positioned at about the center of the bell mouth 104 as shown in Fig. 5 (c) along the airflow direction at the position where the outer periphery 102f becomes the nearest to the bell mouth 104. In an alternative embodiment, the outer periphery 102f of the fan blade 102-2 can be shifted from the center of the bell mouth 104 toward the HEX 125.

The bell mouth 104 comprises generally a rectangular cross-section with its corners are rounded to form a flat region and near circle regions. The flat region faces to the fan blade 102-1, 102-2, and 102-3 and extends to the direction of the airflow while surrounding the propeller fan 102. The bell mouth 104 rectifies the airflow passing through the ODU 101.

Although the direction of the shift and its amounts may change depending on particular requirements and shapes of the fan blades 102-1, 102-2, and 102-3 and so on. In one exemplary embodiment, when the propeller fan 102, i.e., the fan blades 102-1, 102, and 102-3 is shifted toward the direction of the HEX 125, the air-blow performance and the shaft power can be favorably improved as discussed later. Again, it is noted the relative position between the fan blades 102-1, 102-2, and 102-3 and the bell mouth 104 are explained only one example for well understanding the principle of the present invention, and the present invention is not limited to and/or is not considered as exhausted sorely to the disclosed embodiments.

Fig. 6 shows an alternative embodiment set forth where the position of the propeller fan 102, i.e., fan blades 102-1, 102-2, and 102-3 is shifted toward the HEX 125. In the exemplary embodiment in Fig. 6, the the center of the outer periphery 102f of the fan blade 102-1 are positioned about 10 mm inward with respect to the center of the bell mouth 104. Further another embodiment, the propeller fan 102 can be positioned at about 20 mm inward with respect to the bell mouth 104.

Now, referring to Fig. 7-10, the embodiments of the present invention and their practical advantage will be described by using simulated results.

The inventors configured the ODU 101 shown in Fig. 2, and its several performances were measured in several conditions. As a comparative example, another ODU including similar configurations except for the conventional fan blade likely to the propeller fan 400 being installed was used. Following table lists the condition of simulations.

1) having configuration of fan blade 102 in Fig. 4.
2) having configuration of likely to fan blade 400 in Fig. 4.
3) shift amount to inward (to HEX 125) in mili-meters (mm) from normal position.
4) dimensions of shroud position from front panel is in (mm)

Fig. 7 shows the results simulated under a rotation rate (RPM) as a table, and the results are summarized as follows:
1) In the same RPM, the airflow of the conventional ODU is reduced drastically by 14.1% in the reverse rotation, and the shaft power is reduced by 12.2% as compared with those when operated in the positive rotation.
2) In the same RPM, Examples 1-4 shows no drastic reduction and/or change in the airflow rates and the airflow rates in the reverse rotation increase for Example 1 -2 and slightly reduces in Examples 3-4. With respect to the shaft power for the positive rotation and the reverse rotation as compared with comparative example, Examples 1-4 show increase of the shaft power .
3) In the same RPM, the airflow of Examples 1-4 are kept within the range of 10%, and particularly, Example 3 shows the most excellent performances both in the airflow rate and the shaft power.
4) In the same RPM, In the positive rotation, the airflow of Example 3, as in the best result listed in the last column of the table shown in Fig. 7, increases by 5% and the shaft power increases by 16.4 % when compared with the comparative example. In the reverse rotation, the airflow in Example 3 increases by 21.2% and the shaft power increases by 31.5 % when compared with the comparative example as listed in the last column of the table in Fig. 7.

The last row of the table in Fig. 7 lists the shaft power changes when the RPMs of the propeller fan 102 are kept constant in the positive and reverse rotations. As shown in Fig. 7, all Examples shows relatively low changes between the rotational direction compared to the comparable example. Particularly, Example 3 (propeller fan 102 being positioned 10 mm inward) shows excellent results of the reduction by 0.9 % in the airflow and the reduction by 0.7 % in the shaft power between the positive and the reverse rotations when compared with its positive rotation as shown in Fig. 7.

Since the propeller fan 102 according to one or more embodiment of the present invention tends to increase the airflow rate when compared to the conventional propeller fan in the same rotational rates, the inventors further examined the performances of the ODU 101 equipped with the propeller fan 102 according to one or more embodiments and the comparative example in the same airflow rate of 3553 CMH (cubic meter per hour) in the positive and reverse rotations for examining performance change in the same airflow. The results are shown in Fig. 8 as a table.

As shown in Fig. 8, the ODU 101 according to the present invention shows excellent low changes on the shaft power for both the positive rotation and the reverse rotation as compared to shaft power of positive rotation of comparative example, while the comparative example shows significant increase in the shaft power by 38.7% in reverse rotation to keep the air flow rate to 3553 CMH as compared to its shaft power in the positive rotation.

It is noted that the shaft power, particularly of Example 3 is kept within 2.5% in the reverse rotation of the same airflow; this means that the shaft power of Example 3 is substantially kept constant regardless to the rotational direction of the propeller fan 102 at the same airflow rate. Hence, with the propeller fan according to one or more embodiments of the present invention, when the non-azeotropic refrigerant is used, the target performance requirements for suppressing performance change between the positive and reverse rotations, may be satisfied.

As set forth above, it is concluded that the ODU 101, e.g. the propeller fan 102 equipping the fan blades 102-1, 102-2, and 102-3 according to one or more embodiments of the present invention can provide the counter-flow to the heat exchanger (HEX) 125 without significant deteriorations on the air-conditioner performance such as the airflow rates and the shaft power. Hence, the efficiency of the air-conditioning apparatus 100, which uses non-azeotropic refrigerant, can be improved significantly and can also contribute to reduction in Global Warning according to the present invention.

Based on the above observation, the inventors have further examined performances for the shaft power and rotational rate (RPM) under the same airflow rate at 3553 CMH). The results are shown in Fig. 9 as a table. As shown in Fig. 9, it is found that the reduction in the rotation rates in RPM are reduced by 4.8% and 3.9% both in the positive and reverse rotations, in Example 3, respectively while keeping the shaft power to be substantially same with the conventional ODU. This means that relative positionings of the fan blades 102-1, 102-2, and 102-3 has importance in the performance of the fan blades 102-1, 102-2, and 102-3 of one or more embodiment of the present invention.

From the results shown in Fig. 9, the ODU 101, i.e., the fan unit comprising a propeller fan 102/fan blades 102-1, 102-2, and 102-3 can suppress excellently the performance change between the positive rotation and the reverse rotation while keeping the requirements such as airflow rates and the shaft power without significant defects compared to the conventional ODU.

Fig. 10A shows a graph of results of a cycle simulation of the air-conditioning apparatus 100 according to one or more embodiments of the present invention in the heating mode by assuming that the ODU 101 includes the fan unit including the propeller fan 102 of one embodiment of the present invention. The cycle simulation during the heating mode indicates improvement of an APF (Annual performance factor) value with the non-azeotropic refrigerant such as R454B, 50% of R32 and 50% of R1234yf, R454A, and R454C and the like.

The APF value increases gradually as the temperature glide increases up to 5K and the APF level starts to decrease slowly from the temperature glide of 5K, which means that present invention can provide a wider margin to the temperature glide of the non-azeotropic refrigerant such that the present invention can realize usage of wide variety of the non-azeotropic refrigerant while improving APF value. Fig. 10B shows parameters in the simulation for Examples and the comparative example and the simulated APF values as well as the simulated APF values. As shown in Fig. 10B, the conventional propeller fan decreases the APF value due to the reverses rotation, however, the propeller fan of the present embodiments improves the APF values.

Casing Structure
While the configuration of the ODU 101 has been described so far, the air-conditioning performance will be improved by adjusting the airflow characteristics around the ODU 101. Fig. 11 shows a result of a CFD (Computational Fluid Dynamics) calculation of the airflow around the ODU 101A (equipping conventional propeller fan) and the ODU 101 (equipping present propeller fan 102) in the reverse rotation operation. In Figs. 11, 13, 15, 17, 19, and 21, the airflow directions of the outdoor air drawn into the ODU 101, 101A are illustrated by arrows E.

A simulation 1110 shows the airflow around the ODU 101A equipping the conventional propeller fan likely to the propeller fan 400 in the reverse rotation operation. A simulation 1120 shows the airflow around the ODU 101 equipping the propeller fan 102 of one embodiment of the present invention in the reverse rotation operation.

In addition, the airflow discharged from the ODU 101, 101A though the slots 105 of a lateral side of the casing 108 of the ODU 101, 101A is shown by lines and this direction is illustrated by curved thick arrows in Fig. 11. In Figs. 13, 15, 17, 19, and 21, these thick arrows are omitted for clearness of the results.

Furthermore, velocities of the airflow are represented by a heat map and deeper colors indicates high velocities in each of the drawings. As clearness of the airflow directions in drawings, the outdoor air is drawn from the front side and has large velocities as the gray becomes deeper, and the air drawn into the ODU 101, 101A are discharged from the back side and lateral side of the casing 108 of the ODU 101, 101A.

With respect to the ODU 101A, which includes the conventional propeller fan likely to the propeller fan 400, the outside air is drawn into the ODU 101A due to thereverse rotation of the propeller fan 400. In the reverse rotation, the drawn airflows flow toward the HEX 125 and after the heat exchange air is discharged from the real side opening and slots 105 positioned at a lateral side of the casing 108 of the ODU 101A.

The discharged airflow tends to go round to the front side where the outside air is drawn into the ODU 101 due to the reverse rotation operation. This movement of the airflow discharged from the lateral side (through the slot 105) is referred as “short cycling” in this disclosure, and such short cycling causes negative effect on the air-conditioning performance both of ODUs 101, 101A.

As illustrated in CFD result 1120, in the ODU 101 including the propeller fan 102 of one embodiment of the present invention, the discharged air from the lateral side tends to go round to the front panel side along shorter paths when compared to the conventional ODU 101A such that the short cycling has to be suppressed more effectively in the ODU 101 equipping the propeller fan 102 according to one or more embodiment according to the present invention.

For suppressing the short cycling of the discharged air, one or more embodiments may adopt a wind guide disposed around the lateral side of the ODU 101. One embodiment of such wind guide 1201 is shown in Fig. 12. In Fig. 12, Fig. 12 (a) shows an exploded front view of the ODU 101; Fig. 12 (b) shows an exploded rear view of the ODU 101; and Fig. 12 (c) shows a front perspective view of the ODU 101 to which the wind guide 1201 is integrated to the ODU 101.

The wind guide 1201 may be attached to the ODU 101 at the lateral side to which the slots 1202 are formed by any fixture known in this technical art such as snap-in hooks, bolt screw, and the like. The wind guide 1201 shown in Fig. 12, particularly shown in Fig. 12 (c), comprises opposite bottom and top walls 1201a, 1201d and paired opposite-lateral walls 1201b. The lateral walls 1201b are integrated to the top and bottom walls 1201a and 1201d with their respective vertical edges to define a box-like shape leaving opposite apertures 1201c, 1201f between each of walls 1201a, 1201b, 1201c and 1201d.

Each of the lateral walls 1201b has a first sub-wall extending vertically from the edge contacting to the ODU 101 and a second sub-wall extending from the first sub-wall slantingly toward the opposite lateral walls 1201b for forming narrower aperture 1201c than the opposite aperture 1201f formed adjacent to the ODU 101.

The paired bottom and top walls 1201a, 1201d are slanted toward the upper aperture 1201c from the lower aperture 1201f respectively. The lateral walls 1201b and paired top and bottom walls 1201a, 1201d form a shape likely to a hood on the slots 1202 for allowing the exhausted air to be discharged distally to the ODU 101 while suppressing the short cycling of the exhausted air. This wind guide may be fabricated in low cost and is also simple in construction to be installed to the lateral side of the ODU 101

Fig. 13 shows the CFD simulations 1310, 1320 illustrating the effect of the wind guide 1201 and Fig. 13 (a) is a wide view 1310 around the ODU 101 and Fig. 13 (b) is an enlarged view 1320 round the ODU 101. As seen from Fig. 13, the short cycling of the exhausted air can be effectively suppressed when compared to Fig. 11 (illustration 1120) due to the installation of the wind guide 1201.

Fig. 14 shows another embodiment of the wind guide 1401 according to one or more embodiments according to the present invention. In Fig. 14, Fig. 14 (a) shows an exploded front view of the ODU 101; Fig. 14 (b) shows an exploded rear view of the ODU 101; and Fig. 14 (c) shows a front perspective view of the ODU 101 to which the wind guide 1401 is integrated. The wind guide 1401 of Fig. 14 generally has similar shape to the wind guide 1401 shown in Fig. 12 except for the bottom and top wall 1401a, 1401d, which extend horizontally from the lateral side of the ODU 101. This wind guide may also be fabricated in low cost and is also simple in construction to be installed to the lateral side of the ODU 101.

Fig. 15 shows the effect of the wind guide of Fig. 14 as the CFD simulations 1510, 1520, and Fig. 15 (a) is a wide view 1510 around the ODU 101 and Fig. 15 (b) is an enlarged view 1520 around the ODU 101. As seen in Fig. 15, the short cycling of the discharged air can also be effectively improved when compared to the case where the wind guide is not used as in Fig. 11.

Fig. 16 shows another embodiment of the wind guide 1601 according to one or more embodiments according to the present invention. In Fig. 16, Fig. 16 (a) shows an exploded front view of the ODU 101; Fig. 16 (b) shows an exploded rear view of the ODU 101; and Fig. 16 (c) shows a front perspective view of the ODU 101 to which the wind guide 1601 is integrated.

The wind guide 1601 of Fig. 16 has also paired lateral walls, however, a first lateral wall 1601b near to the front side of the ODU 101 has longer length than the second lateral wall 1601b and has a convex curve extending smoothly from the edge adjacent to the ODU 101 to the upper aperture 1601c.

A second lateral wall 1601b opposite to the first lateral wall 1601b has a shorter length than the first lateral wall 1601b and extends generally vertically from the edge adjacent to the ODU 101. The first lateral wall 1601b functions as the wind guide to the discharged air to deflect the airflow opposite to the front face of the ODU 101 such that the short cycling can be effectively improved. This wind guide may also be fabricated in low cost and is also simple in construction to be installed to the lateral side of the ODU 101.

Fig. 17 shows the effect of the wind guide of Fig. 16 as the CFD simulations 1710, 1720, and Fig. 17 (a) is a wide view 1710 around the ODU 101 and Fig. 17 (b) is an enlarged view 1720 around the ODU 101. As seen in Fig. 17, the short cycling of the discharged air can be effectively improved when compared to the case where the wind guide is not used as in Fig. 11.

Fig. 18 shows still another embodiment of the wind guide 1801 and Fig. 18 (a) shows an exploded rear view of the ODU 101; Fig. 18 (b) shows a rear view of the ODU 101 integrated with the wind guide 1801; and Fig. 18 (c) shows a front perspective view of the ODU 101 to which the wind guide 1801 is integrated.

In the embodiment shown in Fig. 18, to prevent the short cycling, multiple plates inclined opposite to the front face of the ODU 101 are formed to the wind guide 1801 and openings formed between the inclined plates allows the discharged air to escape from the ODU 101 toward the rear side. The inclined plates are disposed in the same pitch along the horizontal direction and also along the vertical direction, respectively to form the configuration likely to a louver on the lateral side of the ODU 101 toward the rear side.

Each of the inclined plates has, in one embodiment, about 23 mm in length and are inclined at an angle of about 45 degrees. Due to the inclination of the plates, the discharged flow from the slots 1802 on the casing 108 is deflected towards the back side of the ODU 101, and thus, the short cycling can be improved. Furthermore, this wind guide may be fabricated in low cost and is simple in construction to be installed to the lateral side of the ODU 101.

Fig. 19 shows the effect of the wind guide of Fig. 18 as the CFD simulations 1910, 1920, and Fig. 19 (a) is a wide view 1910 around the ODU 101 and Fig. 19(b) is an enlarged view 1920 around the ODU 101. As seen in Fig. 19, the short cycling of the exhausted air can be effectively improved as well when compared to the case where the wind guide is not used as in Fig. 11.

Fig. 20 shows still further another embodiment of the wind guide, and Fig. 20 (a) shows an exploded front view of the ODU 101; Fig. 20 (b) shows a front perspective view of the ODU 101 to which the wind guide 2001 is integrated.

In this embodiment, to prevent the short cycling, rectangular inclined wind guides segments facing to opposite the front side of the ODU 101 are formed to the wind guide 2001 at the corresponding positions to the slots 2001 as shown in Fig. 20. The length of each rectangular wind guides can vary, but not limited to, from about 20 mm to about 25 mm at an angle of 45 degrees extending opposite to the front face of the ODU 101. Due to its shape and inclination angle, the short cycling can be improved efficiently. This wind guide may also be fabricated in low cost and is also simple in construction to be installed to the lateral side of the ODU 101.

Fig. 21 shows the effect of the wind guide of Fig. 20 as the CFD simulations 2110, 2120, and Fig. 21 (a) is a wide view 2110 around the ODU 101 and Fig. 21 (b) is an enlarged view 2120 around the ODU 101. As seen in Fig. 21, the short cycling of the exhausted air can be effectively improved when compared to the case where the wind guide is not used as in Fig. 11.

In the above-described embodiments of the wind guide 1201, 1401, 1601, 1801, and 2001the discharge directions are explained that the discharge directions are to be the rear side, however, the discharge directions are not limited to, any direction other than the direction toward the front side, such as above, below and distally may be contemplated.

Fig. 22 A shows further another embodiment for enhancing the performance, and Fig. 22A (a) shows a front view of the ODU 101; Fig. 22A (b) shows a perspective rear view of the ODU 101; and Fig. 22A (c) shows an enlarged configuration of the slots 2202.

To further improve the airflow performance of the ODU 101 in both positive and reverse rotations, the embodiment shown in Fig. 22A comprises crosspieces for defining the slots 2202 formed on the casing 108 and each of the crosspieces have pair of inclined surfaces thereon towards the HEX 125 as shown in Fig. 22A. This configuration provides a rectangular cross-sectioned crosspiece 2203 facing its top inward. The inclined surfaces formed on the crosspieces 2203 have, in one embodiment, an about 5 mm length and the angle of the inclination is about 30 degrees. The length and angle can vary depending upon the performance change. In addition, this slot shape may be used in combination with the above wind guides 1201, 1401, 1601, 1801, and 2001 to further improve the performance.

Fig. 22B shows an enlarged shape of crosspieces 2203 forming slots at a casing. Fig, 22B (a) shows an exploded rear view and Fig. 22B (b) shown an enlarged view of the slots 2202 formed by the rectangular crosspieces 2203. Due to the shape of the crosspieces 2203, the velocity distribution may be improved when compared to the case where simple slots. Fig. 23 shows an effect of crosspiece shapes on the airflow performance of one or more embodiment according to the present invention as a form of a table. Because of this configuration of the slot 2202, the airflow performance increases as shown in Fig. 23. For example, in the same RPM, the airflow increases by 1.2% both in the positive and reverse rotations. In addition, in the same airflow rate, the shaft power reduces by 2.7% and 2.2% both in the positive and reverse rotations, respectively.

Figs. 24 -27 show CFD simulations 2410-2720 for the velocity distribution of the inside the ODU 101 of the ODU 101 of Example 3 with the triangular-shaped slots rectangular shaped crosspieces 2203 and with conventional simple rectangular-shaped slots 105. All figures indicate speed-up of the exhausted air through the rectangular shaped crosspieces 2203 on the lateral side of the ODU 101, which further contributes the discharged air to impart higher velocity which enhances the performance both in the positive and reverse rotations. In Figs. 24-27 improved velocity regions are indicated by arrows.

The present invention has been described so far with referring to accompanied drawings. The embodiments described and the drawings are provided only examples for understanding spirit of the present invention to those skilled in the art and should not be understood as any limitation to invention recited in claims.

The term used in the present disclosure has been selected to best explain the embodiments and principles of the present invention and does not imply any limitation to the claimed invention. The terms should be understood as its positive technical meaning, lexical meaning, and/or meaning that those skilled in the art usually uses to describe features and/or elements.

In the above disclosure, if numerical values are described accompanied with the word “about”, it should be understood that such numerical feature includes the numerical value per se, a range in a measurement error known in the art when the present application is filed, or further ±5% - ±10% range of the numerical value, within which the technical advantage of the present disclosure can be realized. In addition, the terms accompanying “almost” and/or “substantially” includes the range of elements and/or features that a person with ordinary skill in the art would understand elements and/or features designated by such terms as is.

It is also understood that a person skilled in the art understands many alternatives, modifications, and/or variations to explicitly described and/or implied embodiments and examples from the disclosures of the present specification; however, such alternatives, modifications, and/or variations and/or their equivalents should fall within the scope of the present invention recited in claims so far as such alternatives, modifications, and/or variation and/or equivalents exhibit technical advantages and spirit of the present invention described in this disclosure. The true scope of the present invention should be solely understood from features and elements as claimed in appended claims.

According to the present invention, an air-conditioning apparatus and casing structure suitably used to non-azeotropic refrigerant can be provided, which can provide excellent flow rates to forward and reverse directions, acceptable static pressure rise, efficiency, and noise suppression while contributing Global Warming Solution.

Brief Description of Signs and Numerals

100- air-conditioning apparatus
101- outdoor unit (ODU)
102- fan unit
102-1,102-2, 102-3- fan blade
103- hub
104- bell mouth
105- slots
106- wind guide
107- front grill
108- casing
125- heat exchanger (HEX)
126- compressor
201- support member
202- fan motor
203- airflow (reverse direction)
204- airflow (positive direction)
400- conventional propeller fan

Claims

　An air-conditioning apparatus, comprising a heat exchanger, a fan unit, refrigerant conducting heat exchange with the heat exchanger, and a casing enclosing at least the heat exchanger and a fan unit, the air-conditioning apparatus comprising:
　a fan unit comprising a propeller fan, the propeller fan rotating in a positive direction and a reverse direction depending on operating modes of the air-conditioning apparatus; and
　a fan motor for rotating the propeller fan in the positive direction and in the reverse direction to achieve a counter-flow heat exchange condition regardless of the operating modes,
　wherein the propeller fan includes a plurality of fan blades having a symmetrical shape with respect to a symmetry axis passing a center of the propeller fan and a positive rotation generates an airflow in a direction from the heat exchanger to a fan unit, and a reverse rotation generates another air flow in a direction from the fan unit to the heat exchanger depending on the operating modes of the air-conditioning apparatus.
　The air-conditioning apparatus according to claim 1, wherein the refrigerant is non-azeotropic refrigerant.
　The air-conditioning apparatus according to claim 1, wherein the outdoor unit using a refrigerant that has temperature glide more than 3 degrees.
　The air-conditioning apparatus according to claim 1, wherein the fan blade comprises generally a flat shape with slanting toward the airflow, and angles of slants to a horizontal plane change with respect to radial positions on the fan blade.
　The air-conditioning apparatus according to claim 1, wherein the air-conditioning apparatus further comprises a bell mouth having a flat region facing to the fan blade and extending to a direction of the airflow while surrounding the propeller fan, and a center of an outer periphery of the fan blade is positioned in a level within the flat region facing to the fan blade.
　The air-conditioning apparatus according to claim 5, the center of the outer periphery of the fan blade is positioned at a center of the flat region of the bell mouth or is shifted toward the heat exchanger from the center of the flat region.
　A casing for an outdoor unit of an air-conditioning apparatus comprising
　a wind guide integrally disposed to a lateral side of the air-conditioning apparatus, the wind guide allowing an airflow discharged from the lateral side to exit distally from a front side of the air-conditioning apparatus which may prevent short-cycling in reverse rotation of propeller fan, wherein the outdoor unit comprising:
　a heat exchanger, a fan unit, non-azeotropic refrigerant conducting heat exchange with the heat exchanger, and the casing enclosing the heat exchanger, the air-conditioning apparatus comprising:
　a fan unit comprising a propeller fan, the propeller fan rotating in a positive direction and a reverse direction depending on operating modes of the outdoor unit; and
　a fan motor for rotating the propeller fan in the positive direction and in the reverse direction to achieve a counter-flow heat exchange condition regardless of the operating modes,
　wherein the propeller fan includes a plurality of fan blades having a symmetrical shape with respect to a symmetry axis passing a center of the propeller fan.
　The casing according to claim 7, wherein the wind guide has an aperture or apertures positioned distally from the front side of the outdoor unit.
　The casing according to claim 7, wherein the wind guide has inclined apertures facing to a rear side or forms inclined apertures to a rear side of the outdoor unit.
　The casing according to claim 7, wherein the casing comprises a plurality of slots at the lateral side of the outdoor unit, and the plurality of slots is configured by crosspieces having almost a rectangular cross-section with facing its top to the heat exchanger.