The disclosure relates to a heat exchanger of an air conditioner.
Conventionally, in a so-called fin-and-tube type heat exchanger, in order to increase the heat exchange efficiency, a cut-up member is provided not in a simple plate-like fin but in a spacing direction from each fin.
For example, when air passes through a flat-plate-shaped fin without a cut-up member, a temperature boundary layer is formed from an air inlet end of the fin, and the temperature boundary layers of each fin come into contact with each other at a position spaced a predetermined distance from the air inlet to an air outlet. As a result, the local heat transfer coefficient becomes lower at the same time as the temperature boundary layer develops, and the heat transfer coefficient becomes constant from a point where the temperature boundary layers contact with each other. On the other hand, when the cut-up member is formed on the fin, a new temperature boundary layer also develops at the air inlet end of each cut-up member, so that a high local heat transfer coefficient may be maintained at each position. Therefore, the total average heat transfer coefficient of the fin having the cut-up member may be made larger than the average heat transfer coefficient of the flat fin.
In addition, the average heat transfer coefficient as described above is influenced not only by the shape and size of the cut-up member but also by the spacing of refrigerant pipes passing through the fins.
If the height of the cut-up member becomes excessively large, the distance between the adjacent fins and the cut-up member becomes excessively small, thus the ventilation resistance becomes large. In this case, since it becomes difficult for air to pass between the fin and the cut-up member, the pressure loss becomes large and the energy efficiency is lowered.
In addition, in order to further improve the heat transfer coefficient in the presence of the cut-up member, there is still room for improvement as to how to arrange the refrigerant pipe.
It is an object of the present disclosure to provide a heat exchanger capable of increasing the effect of promoting heat transfer with air and suppressing an increase in the ventilation resistance to the greatest extent possible to solve the above problem.
In an air conditioner including a heat exchanger according to an aspect of the present disclosure, the heat exchanger includes a refrigerant pipe and a plurality of fins including a first fin and a second fin which are spaced apart from each other in an extension direction of the refrigerant pipe, wherein the first fin includes a flat portion and a cut-up member protruding in an arrangement direction of the second fin in the flat portion, and the height of the cut-up member in the extension direction is between 0.5 and 0.7 times the distance between the first fin and the second fin.
Also, a diameter of the refrigerant pipe is defined as D, the diameter of the refrigerant pipe satisfies 4.5 mm≤D≤5.5 mm.
Also, the refrigerant pipe includes a plurality of the refrigerant pipes, and the plurality of refrigerant pipes include a first refrigerant pipe and a second refrigerant pipe spaced apart from each other in a first direction that is an extension direction of the plurality of fins, a distance from the center of the first refrigerant pipe to the center of the second refrigerant pipe is defined as Dp, and the distance from the center of the first refrigerant pipe to the center of the second refrigerant pipe satisfies D*2.5≤Dp≤D*3.5.
Also, the plurality of refrigerant pipes further include a third refrigerant pipe spaced apart from the first refrigerant pipe in a second direction perpendicular to the first direction, wherein a distance from the center of the first refrigerant pipe to the center of the third refrigerant pipe in the second direction is defined as Lp, and the distance from the center of the first refrigerant pipe to the center of the third refrigerant pipe in the second direction satisfies D*2.0≤Lp≤D*2.5.
Also, the cut-up member includes a body portion spaced apart from the flat portion so that a slit is formed between the flat portion and the cut-up member, and an end portion connected to the flat portion at both ends of the body portion is formed to be inclined from 40 to 50 degrees with respect to the flat portion.
Also, the cut-up member includes a body portion spaced apart from the flat portion so that a slit is formed between the flat portion and the cut-up member, and an end portion connected to the flat portion at both ends of the body portion is formed to be inclined from 40 to 50 degrees with respect to the flat portion.
Also, the cut-up member protrudes from only one side of the flat portion
Also, the first fin further includes a through hole through which the refrigerant pipe passes, and the cut-up member includes a plurality of cut-up members, wherein a plurality of body portions of the plurality of cut-up members extends in a direction corresponding to a longitudinal direction of the first fin, and a plurality of end portions of the plurality of cut-up members is provided so as to surround the peripheries of the through hole.
Also, the longitudinal direction of the first fin is defined as a first direction and a direction being perpendicular to the first direction in which air flows into the heat exchanger is defined as a second direction, wherein the plurality of cut-up members includes a first cut-up member adjacent to the center of the through hole in the second direction, and a second cut-up member adjacent to an edge of the first fin in the second direction.
Also, an angle of an end of the first cut-up member with respect to the second direction is smaller than an angle of an end of the second cut-up member with respect to the second direction
Also, the angle of the end of the second cut-up member with respect to the second direction is formed between 20 degrees and 50 degrees with respect to the second direction.
Also, the plurality of cut-up members protrudes at the same height with respect to the flat portion
In an air conditioner including a heat exchanger according to another aspect of the present disclosure, the heat exchanger includes a refrigerant pipe extending in a first direction and a fin extending in a second direction orthogonal to the first direction through which the refrigerant pipe passes through, and when air flows into the fin in a third direction orthogonal to the first direction and the second direction, the fin includes a plurality of cut-up members having a first cut-up member protruding in the first direction and disposed on the inflow side of the air on the fin, and a second cut-up member protruding in the first direction and disposed on the outflow side of the air, and an area of the fin where the first cut-up member is disposed is smaller than an area of the fin where the second cut-up member is disposed.
Also, an extension length of the first cut-up member in the second direction is shorter than an extension length of the second cut-up member in the second direction.
Also, the refrigerant pipe includes a plurality of the refrigerant pipes, and the plurality of refrigerant pipes include a first refrigerant pipe and a second refrigerant pipe spaced apart in the second direction, and the plurality of cut-up members are disposed between the center of the first refrigerant pipe and the center of the second refrigerant pipe with respect to the second direction, and the second cut-up member extends in the second direction adjacent to the center of the first refrigerant pipe than the first cut-up member.
Also, the first cut-up member and the second cut-up member are respectively provided in plural, and the total number of the first cut-up members is smaller than the total number of the second cut-up members.
In accordance with the heat exchanger of the present disclosure, it is possible to optimize both the heat transfer effect with air and the effect of suppressing an increase in the ventilation resistance.
A heat exchanger 100 according to an embodiment of the present disclosure and an air conditioner using the heat exchanger 100 will be described with reference to the drawings. As shown in
As shown in
As shown in
The refrigerant pipe 2 is provided so as to pass through the plurality of fins 1, and refrigerant flows into the inside of the refrigerant pipe 2, and is configured to exchange heat with the air flow passing through the heat exchanger 100 through the outer surface of the refrigerant pipe 2 and the surface of the fin 1.
The refrigerant pipe 2 is provided at predetermined intervals in the vertical direction which is a short direction with respect to the fins 1, as shown in the sectional view of the heat exchanger element 10 in
More specifically, as shown in
Also, when two of the heat exchanger elements 10 are noted, the two heat exchanger elements 10 are provided at predetermined intervals so that the axial distances of the refrigerant pipes 2 in the column direction become a column pitch Lp. Here, in the adjacent heat exchanger element 10, the penetration positions of the refrigerant pipe 2 are crossed when viewed along the column direction.
The fin 1 is provided with a plurality of cut-up members 3 standing up from a flat portion in the separation direction of the respective fins 1. That is, the fin 1 may be provided such that an aluminum plate is press-worked so that a part thereof is sheared and stands in a direction perpendicular to the flat portion.
Further, in the present embodiment, each of the cut-up members 3 protrudes from only one side of the flat portion of the fin 1. By doing so, it is possible to reduce the number of steps for press working and to improve the productivity.
As shown in
As shown in
More specifically, a standing-up side angle between an end on the short-side direction of the cut-up member 3 and the flat plate portion of the fin 1 is configured to be θ which is set to be 40≤≤θ≤≤50.
Also, as shown in
The cut-up member 3 disposed on an air outlet side (the right side of the refrigerant pipe 2 in
A dead region may be formed in a downstream side (the right side of the refrigerant pipe 2 in
An angle formed by the upper end portion or the lower end portion of each of the cut-up members 3 in the column direction (horizontal direction) gradually decreases from the inlet side of the air flow (left side edge in
An angle formed by the column direction and the upper end or the lower end of the cut-up member 3 disposed on the air outflow side is set to be larger than an angle formed by the upper end portion or the lower end portion of the cut-up member 3 disposed on the center A of the refrigerant pipe 2 and the column direction. An angle range of the cut-up member 3 disposed on the air outflow side is set to be not less than 20 degrees and not more than 50 degrees.
This makes it easier for the air flow to flow toward the air outflow side of the refrigerant pipe 2, thereby making it possible to reduce the range of the dead region and to reduce an area of the fin 1 that does not contribute to the heat exchange which increases the heat exchange efficiency.
Next, the change in the heat transfer coefficient due to the formation of the cut-up member 3 in the fin 1 will be described.
In this case, the temperature boundary layer is developed from the fins 1 on both sides, and the temperature boundary layer developed from each of the fins 1 reaches half the distance from the air inflow end to the air outflow end. As a result, the heat transfer coefficient becomes constant after the point where each temperature boundary layer comes into contact with each other.
On the other hand as shown in
On the other hand, when the cut-up member 3 is formed on the fin 1 and a slit is formed between the flat portion of the fin 1 and the cut-up member 3, the pressure loss becomes larger than the original set pitch.
Here, the effect of improving the heat transfer coefficient by forming the cut-up member 3 and the increase of the pressure loss due to the formation of the cut-up member 3 have different characteristics, respectively. The heat exchanger 100 may be most preferable as long as the increase of the pressure loss can be reduced while the heat transfer coefficient is as large as possible.
Therefore, setting design parameters as the pitch of the fin 1 which is the installation interval of each of the fins 1, and the slit height which is the height of the cut-up member 3 of the fin 1, it is simulated how the ventilation resistance, which causes heat transfer coefficient and pressure loss, would change.
On the other hand, as shown in
From the results of these simulations, the HR which may increase the heat transfer performance and reduce the ventilation resistance will be examined. As shown in
Next, the performance calculation, when the heat exchanger 100 as described above mounted on the indoor unit 200 of a 4-Way cassette type air conditioner as shown in
(i) The diameter of the tube Φ, the number of columns, the number of stages, and the pitch of the fin 1 were changed as parameters.
(ii) Heat transfer coefficient ha on the air side and pressure loss dPa were calculated as follows.
h
a
=c
1
a
N
u
/D
e
,Nu=2.1×(PrReDe/L)0.58
dP
a=2ρav2(fL/De),fL/De=c2×0.43+c3×35.1×(ReDe/L)−1.07×c
c1=1.8, c2=6.142, c3=3.451, c4=1.325, De: Representative length, Nu: Nusselt number, Re: Reynolds number, L: width of the fin 1, f: Flow loss coefficient, Vsc: representative velocity, λa: Thermal Conductivity (Air), Pr: Prandtl number (Air), ρa: Density (air).
(iii) Heat transfer coefficient href on the refrigerant and pressure loss dPref were estimated using the following interaction equation.
Refrigerant heat transfer coefficient: href: Gungor and Winterton interaction equation; Refrigerant pressure loss: dPref: Lockhart-Martinelli interaction equation.
Based on this premise, the performance evaluation when the heat exchanger 100 of the present embodiment was applied to the indoor unit 200 of the 4-way cassette was simulated for cooling capacities of 2.2 kW to 16 KW.
As shown in
Therefore, as the heat exchanger 100 for the indoor unit 200 of the 4-way cassette, the maximum performance may be obtained when the value of the pitch of the slit height/the fin 1 is set in the range of 0.5 to 0.7, diameter Do of the pipe is set in the range of 4.5 mm≤≤Do≤≤5.5, the short pitch Dp is set in the range of 2.5Do≤≤Dp≤≤3.5Do, and the column pitch Lp is set in the range of 2.0Do≤≤Lp≤≤2.5Do.
For this reason, the heat exchanger 100 of the present embodiment constitutes the heat exchanger 100 so as to have the above-described numerical value range. Therefore, the ventilation resistance may be reduced while maximizing the heat transfer performance.
Other embodiments will be described.
As shown in
That is, the vertical length of the cut-up member 3 disposed on the left edge side of the fin 1 into which the air flows is shorter than the vertical length of the cut-up member 3 disposed on the right edge side of the fin 1.
In other words, the area of the cut-up member 3 formed on the left side of the fin 1 around the refrigerant pipe 2 may be smaller than the area of the cut-up member 3 formed on the right side of the fin 1 around the refrigerant pipe 2.
The cut-up member 3 is formed on the right side of the refrigerant pipe 2 such that the area of the cut-up member 3 is widened on the air outlet side toward the air outlet side to minimize the dead region.
Also, the cut-up member 3 formed on the right edge of the fin 1 with respect to the up and down direction of the fin 1 is positioned adjacent to the center of the cut-up member 3 disposed on the left edge of the fin 1.
As shown in
That is, the number of the cut-up members 3 formed on the left edge side of the fin 1 and the number of the cut-up members 3 formed on the right edge side of the fin 1 is different from each other.
For example, as shown in
However, the present disclosure is not limited to this, and the number of the cut-up members 3 may be reversed as shown in
Also, in order to achieve the predetermined performance as the heat exchanger 100, the slit height is set such that the value HR of (slit height)/(the fin 1 pitch) is 0.5≤≤HR≤≤0.7. Also, the heat exchanger 100 may be used not only in the air conditioner but also in other refrigeration cycle devices such as a refrigerator. It may be used not only as an indoor unit but also as an outdoor unit.
Other combinations and modifications of the various embodiments may be made without departing from the spirit of the present invention.
Number | Date | Country | Kind |
---|---|---|---|
2016-052942 | Mar 2016 | JP | national |
This application is a 371 of International Application No. PCT/KR2017/002824, filed Mar. 16, 2017, which claims priority to Japanese Patent Application No. 2016-052942 filed Mar. 16, 2016, the disclosures of which are herein incorporated by reference in their entirety.
Filing Document | Filing Date | Country | Kind |
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PCT/KR17/02824 | 3/16/2017 | WO | 00 |