Patent Application
20060272349
The present invention relates to an indoor unit of an air conditioner that uses a fin-tube type heat exchanger to exchange heat between fluid such as air.
An indoor unit of a conventional air conditioner having a fin-tube heat exchanger is disclosed in Japanese Unexamined Patent Application-Publication No. 11-183077 (page 3 of the specification and FIGS. 1 and 2). Grilles serving as air inlets are provided on the top and front sides of the indoor unit, respectively. Louvered portions provided in a heat exchanger used in the indoor unit are partly removed in order to efficiently drain condensed water when the heat exchanger is used as an evaporator.
In another conventional heat exchanger disclosed in Japanese Unexamined Patent Application Publication No. 2000-179993 (page 3 of the specification and FIGS. 1 and 2), in order to enhance the heat exchange performance without reducing the draft resistance, louvered portions in the first row on the windward side are provided on only one of the front and rear sides of each plate fin, and louvered portions in the second row are provided on both the sides.
In the air conditioner disclosed in the former publication, no louvered portion is provided on the surface of a fin at an uppermost front portion in a lower heat exchanger so that condensed water flows down from an upper heat exchanger to a drip pan at a lower portion through the fins without being concentrated at the upper ends of the fins. While this indoor unit has two air inlets disposed at different positions, in a indoor unit having only one air inlet on the upper side, the wind velocity at the lower heat exchanger is insufficient, and the fan input increases.
When the fins of the heat exchanger disclosed in the latter publication are used in a heat exchanger of a similar air conditioner having only an upper air inlet, a sufficient wind velocity is not obtained at the lower heat exchanger because of the louvered portions provided in the first and second rows, and the fan input increases. Moreover, the louvered portions are provided on both sides of the fins in the second row Therefore, when air flows from the heat exchanger into the fan, it is separated by blades in the fan, and the fan input increases.
Accordingly, the present invention has been made to overcome the above problems, and an object of the invention is to provide an indoor unit of an air conditioner having a heat exchanger that ensures a sufficient wind velocity, that prevents the fan input from increasing, and that achieves a high heat transfer performance.
Another object of the present invention is to provide an indoor unit of an air conditioner having a heat exchanger that enhances assembling efficiency.
In order to achieve the above objects, according to an aspect, an indoor unit of an air conditioner according to the present invention includes an air inlet, a plurality of fin-tube type heat exchanger each having heat transfer tubes extending through stacked plate fins, a fan, an air passage, and an air outlet. The fin-tube type heat exchangers are arranged to surround the fan. The air pressure loss of an adjacent heat exchanger disposed adjacent to the air inlet, of the fin-tube type heat exchangers, is larger than the air pressure loss of a remote heat exchanger that disposed farther from the air inlet than the adjacent heat exchanger.
In the indoor unit of the present invention, the air pressure loss of the adjacent heat exchanger disposed adjacent to the air inlet is larger than the air pressure loss of the remote heat exchanger disposed farther from the air inlet than the adjacent heat exchanger. Therefore, a sufficient wind velocity can be obtained at the remote heat exchanger, the fan input is not increased, and a heat exchanger having a good heat transfer performance in heat exchanging is provided.
In these figures, the indoor unit of the air conditioner of the first embodiment includes an air inlet 7 of an upper grille, a heat exchanger 4 provided on the upstream side of air flows to surround a circulating fan 5, an air passage 6 defined by a casing for guiding air, which passes through the upper grille, the heat exchanger 4 and the circulating fan 5, to an air outlet 17, a condensed-water receiver 19 provided below the heat exchanger 4, and a housing including a front panel 8. In the indoor unit, air is mainly sucked from the upper side, and is blown toward the front lower side.
The heat exchanger 4 includes a lower front heat exchanger 4a substantially vertically standing at the lower front of the indoor unit, an upper front heat exchanger 4b provided between the upper grille 7 and the lower front heat exchanger 4a and slightly tilted so as to make its upper portion positioned backward and its lower portion positioned forward, and a rear heat exchanger 4c provided to extend from the upper grille 7 to the lower rear of the indoor unit and slightly tilted so as to make its upper portion positioned forward and its lower portion positioned backward. These heat exchangers 4a to 4c are arranged to surround the circulating fan 5.
The heat exchanger 4 is a fin-tube type heat exchanger including stacked plate fins 1, and heat transfer tubes 2 perpendicularly inserted into the plate fins 1. The pitch Fp in the stacking direction, thickness Ft, and width L of the plate fins 1 are 0.0011 m, 0.0001 m, and 0.0254 m, respectively. The wind velocity Uf at the front face of the heat exchanger 4 (mean wind velocity of the entire heat exchanger) is 1.0 m/s, and the distance Dp between the centers of the adjacent heat transfer tubes 2 is 0.0254 m.
The plate fins 1 in the lower front heat exchanger 4a are flat 3 without louvered portions. Each of the plate fins 1 in the upper front heat exchanger 4b and the rear heat exchanger 4c has a plurality of trapezoidal louvered portions 3. The upper front heat exchanger 4b and the rear heat exchanger section 4c have the same shape, and are produced in the same production line. The plate fins 1 of the rear heat exchanger 4c are partly folded to form a folded portion 21 so that the rear heat exchanger 4c is placed inside a rear guider.
The lower front heat exchanger 4a, the upper front heat exchanger 4b, and the rear heat exchanger 4c are not joined for the entire heat exchanger, but are separate from one another. Therefore, slit patterns of the heat exchangers 4a to 4c can be easily changed.
In
Air does not pass through the front panel 8. Therefore, in a case in which louvered portions are provided in the entire of the lower front heat exchanger 4a, as in the upper front heat exchanger 4b and the rear heat exchanger 4c, the wind velocity near the lower front heat exchanger 4a is much lower than near the other heat exchanger 4b and 4c.
For this reason, the lower front heat exchanger 4a does not have louvered portions in the first embodiment. That is, the air pressure loss of the lower front heat exchanger 4a disposed remotely from the air inlet 7, of the fin-tube type heat exchangers 4a to 4c, is set to be smaller than the air pressure losses of the upper front heat exchanger 4b and the rear heat exchanger 4c disposed near the air inlet 7. Since the air pressure loss of the lower front heat exchanger 4a is smaller than those of the upper front heat exchanger 4b and the rear heat exchanger 4c, the wind velocity on the lower side of the heat exchanger increases, and the intensity of turbulence generated around the vortex in the circulating fan increases. In this case, the static pressure in the vortex decreases, and the efficiency of the circulating fan increases.
In this way, air does not pass through the front panel 8, and is sucked from the air inlet 7 of the upper grille, and the lower front heat exchanger 4a has no louvered portions. Therefore, the front side of the indoor unit is visually simpler than in a case in which an air inlet is provided on the front side, and noise can be reduced. Moreover, a sufficient wind velocity can be ensured at the heat exchanger 4a disposed remotely from the air inlet 7. This prevents the input to the circulating fan 5 from increasing, and enhances the heat transfer performance of the heat exchanger.
A black circle shows a unit operating point when the lower front heat exchanger 4a has louvered portions, and a white circle shows a unit operating point when the lower front heat exchanger 4a has no louvered portions.
When louvered portions are not provided in the lower front heat exchanger 4a, the pressure loss of the lower front heat exchanger 4a is smaller than when louvered portions are provided. The fan characteristic is shifted toward the side where the pressure loss is greater. Since the unit operating point thus shifts from the point 12a to the point 12b, the air volume Ga increases at the same rotation speed. That is, the air volume Ga increases with no louvered portions.
In addition, the rotation torque in the circulating fan 5 can be stabilized, and air rarely flows back between the upstream and downstream sides of the circulating fan 5.
In a case in which the heat exchanger is used as an evaporator, when louvered portions are not provided in the lower front heat exchanger 4a, the drain efficiency for condensed water deposited on the plate fins 1 increases and the pressure loss decreases in comparison with the case where the louvered portions are provided.
For the same air volume, when louvered portions are not provided in the lower front heat exchanger 4a, the speed of rotation is lower than when louvered portions are provided. At the same speed of rotation, the air volume greatly increases, and the heat exchange performance also increases.
In the first embodiment, after the upper front heat exchanger 4b and the rear heat exchanger 4c are produced in the same shape, the portions of the plate fins 1 of the rear heat exchanger 4c which are in contact with the rear guider 18 are folded to form the folded portion 21. Therefore, the production line is simplified and the production cost can be greatly reduced, compared with a case in which the upper front heat exchanger 4b and the rear heat exchanger 4c are produced in different shapes.
When the louvered portion 3 is not provided on the most downstream side, a vortex having a low flow velocity is produced on the trailing side of the heat transfer tubes 2 in the air flow direction. This adversely affects the heat transfer performance, and increases noise in the circulating fan 5. However, the existence of the louvered portion 3 on the most downstream side can overcome these problems.
In this case, the pressure loss caused by air flow through the lower front heat exchanger 4a is smaller than that through the upper front heat exchanger 4b and the rear heat exchanger 4c, and the velocity of the air passing through the lower front heat exchanger 4a increases. Consequently, advantages similar to those of the heat exchanger 4 shown in
In order to reduce the air pressure loss of the lower front heat exchanger 4a, the height Sa of the louvered portions 3 of the plate fins 1 in the lower front heat exchanger 4a is set to be smaller than the heights Sb and Sc of louvered portions 3 of the plate fins 1 in the upper front heat exchanger 4b and the rear heat exchanger 4c. Other structures are the same as those in
In the fifth modification, the plate fins 1 of the lower front heat exchanger 4a, the upper front heat exchanger 4b, and the rear heat exchanger 4c are provided with the louvered portions 3, and the height Sa of the louvered portions 3 of the plate fins 1 in the lower front heat exchanger 4a is smaller than the heights Sb and Sc of the louvered portions 3 of the plate fins 1 in the upper front heat exchanger 4b and the rear heat exchanger 4c. Therefore, the pressure loss caused by air flow through the lower front heat exchanger 4a is smaller than that through the upper front heat exchanger 4b and the rear heat exchanger 4c, and the velocity of the air passing through the lower front heat exchanger 4a increases. Consequently, advantages similar to those of the heat exchanger 4 shown in
The velocity of the air passing through the lower front heat exchanger 4a is further increased by making both the settings shown in
In the sixth modification, the plate fins 1 shown in
That is, at the lowermost end of each plate fin 1 in a lower front heat exchanger 4a, a louvered portion 3 is provided only on the most downstream side in the louver pitch direction. The upstream portion of the plate fin 1 is flat. Plate fins 1 in an upper front heat exchanger 4b and a rear heat exchanger 4c are provided with louvered portions 3. The fin pitch ha between the plate fins 1 in the lower front heat exchanger 4a is set to be longer than the fin pitches hb and hc between the plate fins 1 in the upper front heat exchanger 4b and the rear heat exchanger 4c. In this case, the pressure loss caused by air flow through the lower front heat exchanger 4a is smaller than that through the upper front heat exchanger 4b and the rear heat exchanger 4c, and the velocity of the air passing through the lower front heat-exchanging section 4a increases. Consequently, advantages similar to those of the heat exchanger 4 shown in
While the addition of the auxiliary heat exchanger 4f increases the pressure loss on the lower front side of the indoor unit, the wind velocity on that side increases because air flows in not only from an upper grille 7, but also from the space 20 between the front panel 8 and the condensed-water receiver 19. Consequently, advantages similar to those of the heat exchanger 4 of the first embodiment shown in
When all the louvered portions 3 of the lower front heat exchanger 4a are trapezoidal, as shown in
In contrast, when the louvered portions 3 of plate fins 1 in the lower front heat exchanger 4a, which are provided closest to the circulating fan 5 and on the most downstream side in the row direction, are shaped like a parallelogram having opposite sides inclined downward at the angle θ to the row direction, air passing through the lower front heat exchanger 4a travels downward toward the circulating fan 5, and substantially follows the attack angle of blades in the circulating fan 5 as shown in
In the heat exchanger 4 of the conventional indoor unit, the upper front heat exchanger 4b and the rear heat exchanger 4c are in line contact with each other, and a sealing member 16 is frequently used to prohibit air from passing through the contact portion in order to prevent the air from being concentrated near the contact portion without passing through the heat exchanger. In this case, the air completely flows around the sealing member 16. Therefore, there is a possibility that the heat transfer area will decrease, that the pressure loss will increase, and that the fan input will increase.
In contrast, in the indoor units according to the present invention, an end face 35 of the upper heat exchanger 4b and a side face 36 of the rear heat exchanger 4c are in face contact, as shown in
In addition, since air does not flow through the panel 8, the wind velocity near the contact portion between the upper front heat exchanger 4b and the rear heat exchanger 4c is much higher than in the case where a grille through which air flows is provided on the front side. Therefore, the above-described advantages are improved.
Such an upper contact between the upper front heat exchanger 4b and the rear heat exchanger 4c can also be applied to the above-described structures (counter measures) for reducing the air pressure loss of the lower front heat-exchanging section 4a.
The refrigerant circuit includes a compressor 26, a condensing heat exchanger 27, a throttle 28, an evaporating heat exchanger 29, and a fan 30. The energy efficiency of the air conditioner can be enhanced by applying the heat exchanger of the first embodiment to the condensing heat exchanger 27, the evaporating heat exchanger 29, or both thereof.
Herein, the energy efficiency is given by the following expressions:
Heating energy efficiency=performance of indoor heat exchanger (condenser)/total input
Cooling energy efficiency=performance of indoor heat exchanger (evaporator)/total input
The above-described advantages of the heat exchanger 4 in the first and second embodiments and the air conditioner using the heat exchanger 4 can be achieved with any of refrigerants, for example, HCFC (R22), HFC (R116, R125, R134a, R14, R143a, R152a, R227ea, R23, R236ea, R236fa, R245ca, R245fa, R32, R41, RC318, or a mixture of some of these refrigerants such as R407A, R407B, R407C, R407D, R407E, R410A, R410B, R404A, R507A, R508A, or R508B), HC (butane, isobutane, ethane, propane, propylene, or a mixture of some of these refrigerants), a natural refrigerant (air, carbon dioxide, ammonia, or a mixture of some of these refrigerants), and a mixture of some of the above refrigerants.
While air and the refrigerants are exemplified as the working fluid, similar advantages can be obtained with other gases, liquids, and gas-liquid mixtures.
While the plate fins 1 and the heat transfer tubes 2 are frequently made of different materials, they may be made of the same material such as copper or aluminum. In this case, the plate fins 1 and the heat transfer tubes 2 can be brazed. This dramatically increases the contact heat transfer coefficient therebetween, and greatly enhances the heat exchange performance. Moreover, recyclability is enhanced.
When the plate fins 1 are closely bonded to the heat transfer tubes 2 by furnace brazing, they are coated with a hydrophilic material after brazing. This prevents the hydrophilic material from being burnt during brazing.
Furthermore, the heat transfer performance can be enhanced by applying a heat-radiating coating, which promotes radiant heat transfer, onto the plate fins 1.
The above-described advantages of the heat exchanger 4 in the first and second embodiments and the air conditioner using the heat exchanger 4 can be achieved with any refrigeration oil, such as mineral oil, alkylbenzene oil, ester oil, ether oil, or fluorine oil, regardless of whether the oil can mix the refrigerant.
1. plate fin
2. heat transfer exchanger
3. louvered portion
4. (4a, 4b, 4c) heat exchanger
5. circulating fan
6. air passage
7. air inlet
17. air outlet
20. space
35. end face
36. side face
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-070787 | Mar 2004 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP05/03745 | 3/4/2005 | WO | 3/30/2006 |
