Patent Application
20080035318
The present invention relates to a refrigeration apparatus formed by a heat exchanger that has a heat exchanging surface.
In a refrigeration apparatus in which a heat exchanger is operated as an evaporator, frost usually forms on a heat exchanging surface of the heat exchanger when the temperature of air with which the heat exchanger exchanges heat is low or when the evaporation temperature of the evaporator is low. The frost formation lowers the heat exchanging capability of the heat exchanger, and consequently lowers the refrigeration capability of the refrigeration apparatus.
For example, in the case of a heat pump type air conditioner, which is one type of refrigeration apparatus, the evaporation temperature of an outdoor heat exchanger operating as an evaporator decreases when the outdoor air temperature decreases during operation. As a result, frost forms on the outdoor heat exchanger. The frost formation lowers the evaporation capability of the outdoor heat exchanger, and consequently lowers the heating capability of the air conditioner. To prevent this, the air conditioner performs a defrosting operation when necessary to remove frost from the outdoor heat exchanger. However, the defrosting operation may suspend the heating operation of the air conditioner or lower the heating capability of the air conditioner depending on the type of defrosting operation. This may lower the heating comfort of the air conditioner. Thus, it is required that the refrigeration operation (particularly, the heating operation for the heat pump type air conditioner which is a typical refrigeration apparatus) be extended by delaying frost formation on the heat exchanger and that the time taken by the defrosting operation be shortened.
To meet these requirements, methods for applying a frost formation prevention layer on a heat exchanging surface to reduce the amount of frost formed on a heat exchanger operating as an evaporator have been proposed. The methods for arranging a frost formation prevention layer prevent frost formation by increasing the water slippage and the water repellency of the heat exchanging surface.
Patent publication 1 describes one example of a method for applying a frost formation prevention layer. A coating film is formed by applying a composition containing 3 to 70 part by weight of a specific organo polysiloxane having a silanol group to 100 part by weight of specific organo polysiloxane to a heat exchanging surface and hardening the applied composition. The frost formation prevention layer increases the water slippage and the water repellency of the heat exchanging surface. When the heat exchanger operates as an evaporator in this state, water droplets that have condensed quickly run down on the heat exchanging surface. As a result, the amount of frost formation on the heat exchanging surface is reduced.
A drain pan 46 for receiving water droplets that drip from the heat exchanger 42 and discharging the water droplets is arranged below the heat exchanger 42. An upper surface 46a of the drain pan 46 is inclined to discharge water. The heat exchanger 42 is arranged substantially horizontally relative to the drain pan 46 of which the upper surface 46a is inclined so that a lower end of the heat exchanger 42, or specifically the lower ends of the plate fins 43, partially comes into contact with the upper surface 46a of the drain pan 46.
When the heat exchanger 42 of this structure operates as an evaporator, water droplets 48 that condense on the plate fins 43 run down as indicated by arrow 47. The water droplets 48 that have run down may accumulate and freeze at portions of contact between the lower ends of the plate fins 43 and the upper surface 46a of the drain pan 46. If ice 49 forms at the lower ends of the plate fins 43, the water droplets 48 may run down and reach the ice 49 and freeze. As a result, frost 51 would grow upward from the lower ends of the plate fins 43 as indicated by arrow 50. In this way, the frost 51 grows from the ice 49 formed at the lower end of the heat exchanger 42. Thus, even if the water slippage and the water repellency of the surface of the plate fins 43 is increased, a refrigeration apparatus using the conventional heat exchanger 42 would not sufficiently benefit from the resulting formation reduction effect.
The present invention provides a refrigeration apparatus that reduces the amount of frost that forms when a heat exchanger is operated as an evaporator.
One aspect of the present invention provides a refrigeration apparatus including a heat exchanger and a drain pan. The heat exchanger has a heat exchanging surface and exchanges heat between air circulating along the heat exchanging surface and a heating medium circulating through the heat exchanger. The drain pan is arranged below the heat exchanger. A space is formed entirely between a lower end of the heat exchanger and an upper surface of the drain pan.
Another aspect of the present invention provides a refrigeration apparatus including a refrigeration apparatus includes a heat exchanger and a drain pan. The heat exchanger has a heat exchanging surface and exchanges heat between air circulating along the heat exchanging surface and a heating medium circulating through the heat exchanger. The drain pan is arranged below the heat exchanger. The heat exchanger is arranged in a manner that a lower end of the heat exchanger partially comes into contact with an upper surface of the drain pan. A projection is arranged on the lower end of the heat exchanger, and the partial contact between the lower end of the heat exchanger and the upper surface of the drain pan is performed by a distal end of the projection coming in contact with the upper surface of the drain pan.
A further aspect of the present invention provides a refrigeration apparatus including a heat exchanger. The heat exchanger has a heat exchanging surface and exchanges heat between air circulating along the heat exchanging surface and a heating medium circulating through the heat exchanger. A high temperature portion is arranged below the heat exchanger and heats a water droplet that condenses and runs down the heat exchanging surface to 0° C. or higher when the heat exchanger operates as an evaporator.
A further aspect of the present invention provides a refrigeration apparatus including a heat exchanger. The heat exchanger has a heat exchanging surface and exchanges heat between air circulating along the heat exchanging surface and a heating medium circulating through the heat exchanger. The heat exchanger is a cross fin and tube heat exchanger including a plurality of fins that form the heat exchanging surface and a heat exchanger pipe through which the heating medium circulates. A projection is formed on lower ends of some of the plurality of fins, and the projection projects more downward than lower ends of the other fins.
A further aspect of the present invention provides a refrigeration apparatus including a heat exchanger and a drain pan. The heat exchanger has a heat exchanging surface and exchanges heat between air circulating along the heat exchanging surface and a heating medium circulating through the heat exchanger. The drain pan is arranged below the heat exchanger. The drain pan has an upper surface subjected to a water slipping and water repellent treatment.
A further aspect of the present invention provides a refrigeration apparatus including a heat exchanger and a drain pan. The heat exchanger has a heat exchanging surface and exchanges heat between air circulating on the heat exchanging surface and a heating medium circulating inside the heat exchanger. The drain pan is arranged below the heat exchanger. The drain pan has an upper surface subjected to hydrophilic treatment.
A heat pump type air conditioner, which is one type of refrigeration apparatus, according to a first embodiment of the present invention will now be described with reference to the drawings.
In the air conditioner 1, the outdoor heat exchanger 2, an expansion valve 9, an indoor heat exchanger 10, a four-way switch valve 11, and a compressor 12 are connected by a refrigerant pipe to form a refrigerant circuit as shown in
During a heating operation of the air conditioner 1, the four-way switch valve 11 is set as indicated by broken lines as shown in
As shown in
In the outdoor heat exchanger 2, each plate fin 3, which is arranged in a manner such that its longitudinal direction coincides with the vertical direction, forms a fin line. Although two fin lines are formed in the circulation direction 4 in
A drain pan 6 for receiving water droplets that drip from the outdoor heat exchanger 2 and discharging the water droplets is arranged below the outdoor heat exchanger 2. An upper surface 6a of the drain pan 6 is inclined to discharge water that drips from the outdoor heat exchanger 2. The outdoor heat exchanger 2 is arranged substantially horizontally to the drain pan 6 of which upper surface 6a is inclined.
In the first embodiment, space is formed between the entire lower end of the outdoor heat exchanger 2, or more specifically, lower ends 3a of the plate fins 3, and the upper surface 6a of the drain pan 6. Thus, water droplets 8, which condense when the outdoor heat exchanger 2 operates as an evaporator, run down the surface of the plate fins 3 and drip from the lower ends 3a of the plate fins 3 onto the upper surface 6a of the drain pan 6. With this structure, the outdoor heat exchanger 2 and the drain pan 6 have no contacting portions. The water droplets 8 that have run down do not accumulate at portions of contact between the outdoor heat exchanger 2 and the drain pan 6. This prevents frost from forming from water droplets and growing upward from the lower ends 3a of the plate fins 3.
The first embodiment has the advantages described below.
(1) In the first embodiment, the outdoor heat exchanger 2 and the drain pan 6 have no contacting portions. Thus, the water droplets 8 that have run down the surface of the plate fins 3 do not accumulate at portions of contact between the outdoor heat exchanger 2 and the drain pan 6. As a result, frost is prevented from forming from water droplets and growing upward from the lower ends 3a of the plate fins 3. This reduces the amount of frost formed on the outdoor heat exchanger 2.
The first embodiment may be modified in the following form.
In the first embodiment, a space is formed entirely between the outdoor heat exchanger 2 and the drain pan 6. Thus, air may circulate through the space and lower the heat exchanging efficiency of the outdoor heat exchanger 2. To reduce the amount of air circulating through the space, a shielding member may be arranged on the upper surface of the drain pan 6. In this case, the shielding member is arranged outward from the plate fins 3 so that the shielding member does not come into contact with the plate fins 3.
A second embodiment of the present invention will now be described with reference to FIGS. 3 to 5. The structure of the second embodiment is the same as the structure of the first embodiment except in the shape of the outdoor heat exchanger 2 and the positional relationship between the outdoor heat exchanger 2 and the drain pan 6. The components of the second embodiment common to the first embodiment will not be described in detail.
As shown in
In the second embodiment, the partial contact between the lower end of the outdoor heat exchanger 2, or specifically the lower ends of the plate fins 3, and the upper surface 6a of the drain pan 6 occurs at distal ends of inclined portions 3b, which are formed as projections, on the lower ends of the plate fins 3 that come into contact with the upper surface 6a of the drain pan 6. More specifically, the upper surface 6a of the drain pan 6 is inclined to discharge water, and the outdoor heat exchanger 2 is arranged substantially horizontally so that the lower end of the outdoor heat exchanger 2 partially comes into contact with the upper surface 6a of the drain pan 6. The inclined portions 3b are inclined relative to the air circulation direction 4. As shown in
In the outdoor heat exchanger 2 shown in
In this manner, the distal ends of the inclined portions 3b at the lower ends of the plate fins 3 come into contact with the upper surface 6a of the drain pan 6 in the second embodiment so that the area of contact between the plate fins 3 and the upper surface 6a of the drain pan 6 is reduced as compared with when the plate fins 3 have flat lower ends that come into contact with the upper surface 6a of the drain pan 6. Water droplets 8, which condense when the outdoor heat exchanger 2 operates as an evaporator, run down as indicated by arrow A1 in
FIGS. 5(a) to 5(c) are cross-sectional views showing projections having other shapes that are formed on the outdoor heat exchanger 2. The projections shown in
The projections 3d shown in
The projections 3e shown in
The second embodiment has the advantages described below.
(1) In the second embodiment, the inclined portions 3b and 3c and the projections 3d and 3e of the outdoor heat exchanger 2 come into contact with the upper surface 6a of the drain pan 6. Thus, the area of contact between the plate fins 3 and the upper surface 6a of the drain pan 6 is reduced as compared with the conventional structure in which the lower end of the outdoor heat exchanger 2 is entirely flat and the lower end of the outdoor heat exchanger 2 comes into contact with the upper surface 6a of the drain pan 6. Thus, the amount of ice formed at the portions of contact between the lower end of the outdoor heat exchanger 2 and the upper surface 6a of the drain pan 6 decreases, and the amount of frost growing upward from the contacting portions may be reduced.
(2) The inclined portions 3b and 3c serving as projections are formed easily by diagonally cutting the lower ends of the plate fins 3.
A third embodiment of the present invention will now be described with reference to
In the third embodiment, projections are formed on lower ends of some plate fins 3L in such a manner that the projections extend more downward than lower ends of other plate fins 3S. More specifically, two types of plate fins 3L and 3S that differ in vertical length are used (reference numeral 3 refers generically to the two different plate fins), and each of the plate fins 3L with the long vertical length is arranged at every predetermined number of plate fins 3S with the short vertical length. In
In this way, distal ends of the projections formed on the lower ends of the plate fins 3L, that is, distal ends of the lower ends of the plate fins 3L having the long vertical length come into contact with the upper surface 6a of the drain pan 6 in the third embodiment to enable the outdoor heat exchanger 2 and the drain pan 6 to partially come into contact with each other in the same manner as in the second embodiment. As compared with when all the plate fins 3 in the contact region R come into contact with the drain pan 6, the area of contact between the outdoor heat exchanger 2 and the drain pan 6 is reduced. As a result, the amount of water accumulating at the portions of contact between the outdoor heat exchanger 2 and the drain pan 6 decreases. This decreases the amount of ice formed on the contacting portions.
In the third embodiment, the plate fins 3S do not have any portions arranged between the lower ends of the adjacent plate fins 3L. This enlarges the air circulation passage at the lower end of the outdoor heat exchanger 2. In this case, the airflow resistance of the passage decreases and the airflow velocity increases. As a result, the surface temperature of the plate fins 3 increases. Thus, condensed water is less likely to freeze at the lower ends of the plate fins 3. Further, even if the condensed water freezes at the lower ends of the plate fins 3 and the ice 13 is formed on the plate fins 3, the ice 13 does not close the airflow passage because the airflow passage is large.
The third embodiment has the advantages described below.
(1) In the third embodiment, the lower ends of only the plate fins 3L having the long vertical length in the contact region R come into contact with the upper surface 6a of the drain pan 6. Thus, the area of contact between the outdoor heat exchanger 2 and the drain pan 6 is reduced as compared with the conventional structure in which all the plate fins in the contact region R come into contact with the drain pan 6. As a result, the amount of ice 13 formed on the contacting portions of the lower end of the outdoor heat exchanger 2 and the upper surface 6a of the drain pan 6 is reduced. This reduces the amount of frost growing upward from the contacting portions. Further, the projections are formed easily using the two types of plate fins 3L and 3S having different vertical lengths.
(2) In the third embodiment, the plate fins 3S do not have any portions arranged between the lower ends of the adjacent plate fins 3L. This enlarges the air circulation passage at the lower end of the outdoor heat exchanger 2. In this case, the airflow resistance decreases and the airflow velocity increases. As a result, the surface temperature of the plate fins 3 increases. Thus, condensed water is less likely to freeze at the lower ends of the plate fins 3, and frost formation on lower parts of the plate fins 3 is suppressed. As a result, the amount of frost formation on the outdoor heat exchanger 2 may be reduced.
(3) In the third embodiment, the air circulation passage is enlarged at the lower end of the outdoor heat exchanger 2. Thus, even if the condensed water freezes at the lower ends of the plate fins 3L having the long vertical length and the ice 13 is formed on the plate fins 3L, the ice 13 does not close the passage. As a result, the airflow resistance is prevented from increasing.
The third embodiment may be modified in the following forms.
Portions arranged at large pitches, or more specifically, the surfaces of the projections of the plate fins 3L having the long vertical length, may be subjected to hydrophilic treatment. The projections of the plate fins 3L are portions of the plate fins 3L that project more downward than the plate fins 3S having the short vertical direction. The hydrophilic treatment may, for example, be performed by applying a hydrophilic agent, such as polyacrylic acid, to the plate fins 3 when the plate fins 3 are made of aluminum. When the plate fins 3 are subjected to a water slipping and water repellent treatment and the hydrophilic treatment, the water slipping and water repellent treatment may be performed after or before the hydrophilic treatment is performed. In this way, because the surfaces of the projections are subjected to the hydrophilic treatment, the condensed water spreads thinly on the surface of the plate fins 3. Even when the condensed water freezes, ice resulting from the freezing has a low height from the surface of the plate fins 3. In other words, the ice resulting from the freezing grows toward adjacent plate fins 3 only by a small amount. Thus, the air circulation passage is not closed, and the airflow resistance is prevented from increasing.
Although the third embodiment describes a case in which the outdoor heat exchanger 2 comes into contact with the drain pan 6, a space may be formed entirely between the outdoor heat exchanger 2 and the drain pan 6 in the same manner as in the first embodiment.
A fourth embodiment of the present invention will now be described with reference to FIGS. 7 to 12. The structure of the fourth embodiment is the same as the structure of the second embodiment except in the structure of the outdoor heat exchanger 2. The components of the fourth embodiment common to the second embodiment will not be described in detail.
In the example shown in
The high temperature portion 14 is arranged in this manner. In this case, water droplets 8 that have condensed and run down are heated to 0° C. or higher by the high temperature portion 14 in the lower part when the outdoor heat exchanger 2 operates as an evaporator. As a result, water droplets 8 that have run down do not freeze at the lower end of the outdoor heat exchanger 2.
In the air conditioner 1 shown in
During a cooling operation of the air conditioner 1, the four-way switch valve 11 is set as indicated by the broken line shown in
The high temperature portion 14d functions in the same manner as the high temperature portion 14 shown in
The fourth embodiment has the advantages described below.
(1) In the fourth embodiment, if the water droplets 8 that have condensed run down when the outdoor heat exchanger 2 operates as an evaporator, the water droplets 8 are heated to 0° C. or higher by the high temperature portions 14, 14a, 14b, 14c, and 14d. Thus, the water droplets 8 do not freeze at the lower end of the outdoor heat exchanger 2. As a result, frost is prevented from growing upward from the lower end of the outdoor heat exchanger 2, and the amount of frost formation on the outdoor heat exchanger 2 is reduced.
(2) The high temperature portions 14 and 14b formed by only the plate fins 3 are easily formed by the piped structure or by changing the distance from the lower ends of the plate fins 3 to the lowest position of the heat exchanger pipe 5.
(3) The high temperature portion 14a of which surface is subjected to the hydrophilic treatment prevents the water droplets 8 from growing on the surface of the high temperature portion 14a and prevents the airflow resistance from increasing. This enables the surface temperature of-the high temperature portion 14a to increase. As a result, the temperature of the water droplets 8 increases more in the high temperature portion 14a.
(4) The high temperature portion 14c formed by heating the lower part of the outdoor heat exchanger 2 with the heater 16 is easily formed by arranging the heater 16 in the outdoor heat exchanger 2. Further, as compared with the high temperature portions 14, 14a, and 14b formed by only the plate fins 3, the temperature of the high temperature portion 14c can be set high. The high temperature portion 14c can quickly heat the water droplets to 0° C. or higher.
(5) The temperature of the high temperature portion 14d formed by the lower heat exchanging portion 2b that is obtained by dividing the outdoor heat exchanger 2 into upper and lower parts can be set to be high as compared with the high temperature portions 14, 14a, and 14b formed only by the plate fins 3. The high temperature portion 14d can quickly heat the water droplets to 0° C. or higher.
The fourth embodiment may be modified in the following forms.
Although the high temperature portion 14 is formed only by the plate fins 3 using the pipe-extracted structure, a high temperature portion may be formed by avoiding circulation of the refrigerant in portions of the heat exchanger pipe 5 extended through the portions of the plate fins 3 corresponding to the high temperature portion. In this case, the heat exchanger pipe 5 is extended throughout the plate fins 3. This improves the strength of the structure of the outdoor heat exchanger 2.
A fifth embodiment of the present invention will now be described with reference to
In the fifth embodiment, the upper surface 6a of a drain pan 6 is subjected to a water slipping and water repellent treatment. The water slipping and water repellent treatment is performed by applying a coating film having water slippage and water repellency to the upper surface 6a of the drain pan 6. In this structure, water dripping from the outdoor heat exchanger 2 flows smoothly on the upper surface 6a without accumulating on the upper surface 6a of the drain pan 6.
The drain pan 6 shown in
Further, the upper surface 6a of the drain pan 6 shown in
The fifth embodiment has the advantages described below.
(1) The upper surface 6a of the drain pan 6 is subjected to the water slipping and water repellent treatment so that water dripping from the outdoor heat exchanger 2 flows smoothly without accumulating on the upper surface 6a of the drain pan 6, and the water is drained smoothly. The upper surface 6a of the drain pan 6 is subjected to the water slipping and water repellent treatment and the distance from the highest position of the upper surface 6a to the lowest position of the upper surface 6a is shortened so that the water is drained more smoothly.
A sixth embodiment of the present invention will now be described. The structure of the sixth embodiment is the same as the structure of the fifth embodiment except in the structure of the drain pan 6. The components of the sixth embodiment common to the fifth embodiment will not be described in detail.
In the sixth embodiment, an upper surface 6a of a drain pan 6 is subjected to the hydrophilic treatment. The hydrophilic treatment may, for example, be performed by applying a hydrophilic agent, such as polyacrylic acid, to the upper surface 6a when the drain pan 6 is made of aluminum. Thus, water dripping from the outdoor heat exchanger 2 flows smoothly on the upper surface 6a of the drain pan 6.
The sixth embodiment has the advantage described below.
(1) The upper surface 6a of the drain pan 6 is subjected to the hydrophilic treatment so that water dripping from the outdoor heat exchanger 2 flows smoothly on the upper surface 6a of the drain pan 6, and the water is drained smoothly. The upper surface 6a of the drain pan 6 is subjected to the hydrophilic treatment and the distance from the highest position of the upper surface 6a to the lowest position of the upper surface 6a is shortened so that the water is drained more smoothly.
In the above embodiments, the present invention is applied to a heat pump type air conditioner serving as one type of refrigeration apparatus. However, the present invention may be applied to, for example, a refrigerator or a freezer.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-224898 | Jul 2004 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP05/13954 | 7/29/2005 | WO | 1/16/2007 |
