Heat exchanger

Abstract

The present invention provides a heat exchanger comprising: a first header to which an inlet pipe and an outlet pipe are connected; a second header which is spaced a predetermined distance apart from the first header; a plurality of tubes which are horizontally arranged between the first header and the second header and include a plurality of micro-channels through which refrigerant flows; and fins which are coupled to the outer surfaces of the tubes in parallel with the flow direction of air, wherein the tubes are formed such that the width thereof facing the first header and the second header is smaller than the width of the fins.

Description

heat exchanger

[0001] The present invention relates to a heat exchanger.

[0002] A heat exchanger comprises tubes through which refrigerant flows and multiple fins attached to the outer surface of the tubes. The refrigerant flowing inside the tubes exchanges heat with the air outside the tubes through the multiple fins in contact with the outer surface of the tubes. The refrigerant absorbs heat from the air, and the temperature of the air decreases. Therefore, for the efficiency of the heat exchanger, it is important that heat exchange between the refrigerant and the air occurs efficiently.

[0003] A heat exchanger equipped with microchannels is one of the MEMS (Micro Electron-Mechanical System) technologies.

[0004] Microchannel heat exchangers are fabricated by stacking several to tens of thin, small metal plates equipped with microchannels processed using MEMS (Micro Electro-Mechanical System) technology. Microchannels used in heat exchangers refer to channels with a characteristic length between 1 µm and 1 mm.

[0005] A microchannel heat exchanger is a device that creates narrow microchannels and flows fluid through them to exchange heat between a high-temperature fluid and a low-temperature fluid, and is mainly used for cooling small devices.

[0006] Microchannel heat exchangers utilize the fact that the heat transfer coefficient within the tube is inversely proportional to the tube diameter in steady-state tube flow.

[0007] As the channel size decreases and the number of channels increases, a larger heat transfer surface area per unit volume is achieved, demonstrating superior performance compared to conventional macro-scale heat exchangers while enabling miniaturization and weight reduction. Due to these advantages, interest in the application of microchannel heat exchangers is growing in various fields requiring localized cooling, such as ultra-small electronic devices.

[0008] Generally, microchannel heat exchangers are fabricated by alternately joining different plates in which flow channels are formed by etching the plates. Furthermore, with the advancement of the field of Micro-Electro-Mechanical Systems (MEMS), microchannel heat exchangers can utilize various microfabrication technologies to form millimeter-scale flow channels in diverse shapes.

[0009] Microchannel heat exchangers have the advantage of allowing not only gases but also liquids to flow freely while having a large heat transfer surface area. Therefore, microchannel heat exchangers, which have a large heat transfer surface area relative to the space used, are being applied in various fields, including information technology fields such as computers and semiconductors, as well as energy technology fields such as energy-related industries.

[0010] Furthermore, the ripple effect is significant not only in petrochemical plants requiring high-temperature, high-pressure, and microchannel heat exchangers, but also in other industries such as fuel cell reactors, wastewater treatment systems, CO₂ heat pumps, and water heaters in the refrigeration and air conditioning sector.

[0011] However, as mechanical and electronic equipment has recently become increasingly smaller, the amount of heat generated per unit area has increased significantly, and as a result, problems such as system instability and shutdown of operation are emerging when the cooling system's limits are exceeded.

[0012] In addition, microchannel heat exchangers must be manufactured compactly to optimize thermal performance improvement and raw material cost reduction. In other words, costs can be reduced by decreasing the volume of the tubes and fins.

[0013] However, in the case of compact heat exchangers with reduced volume, problems such as reduced thermal performance, increased pressure loss on the refrigerant and air sides, and issues with product reliability and manufacturability may arise.

[0014] Therefore, heat exchangers manufactured with a compact structure must resolve the problems of reduced thermal performance and increased pressure loss on the refrigerant and air sides.

[0015] Patent Document 1 (KR No. 10-2012-0034499, published April 12, 2012) discloses a microchannel heat exchanger comprising a first inlet plate, a second inlet plate, a first inlet plate, a second inlet plate, and a cover plate, or further comprising a second inlet plate and a third inlet plate between the first inlet plate and the second inlet plate.

[0016] Patent Document 1 is configured to enable fine temperature control and faster heat exchange than conventional heat exchangers by stacking plates with etched microchannels so that cold fluid and hot fluid can flow alternately on one plate.

[0017] However, Patent Document 1 does not include a configuration that reduces the volume of the microchannel heat exchanger to realize a heat exchanger with a compact structure while increasing thermal performance by minimizing the refrigerant differential pressure.

[0018] Patent Document 2 (KR No. 10-0991113, registered on October 26, 2010) discloses a microchannel heat exchanger comprising: a first plate including a plurality of first microchannels formed to allow fluid to pass through; a second plate stacked on top of the first plate and including a plurality of second microchannels formed to allow fluid to pass through, and a first communication hole formed in at least one of the second microchannels to communicate with the first microchannel; and a third plate stacked on top of the second plate and including a plurality of third microchannels formed to allow fluid to pass through, and a second communication hole formed in at least one of the third microchannels to communicate with a second microchannel in which the first communication hole is not formed.

[0019] Patent Document 2 is configured to improve heat transfer efficiency by forming heat flux in multiple directions through a structure in which a flow path through which a high-temperature fluid and a low-temperature fluid pass is interlocked in three dimensions.

[0020] However, Patent Document 2 also does not include a structure that reduces the volume of the microchannel heat exchanger to realize a heat exchanger with a compact structure while increasing thermal performance by minimizing the refrigerant differential pressure.

[0021] Therefore, there is a need to develop a microchannel heat exchanger that can reduce raw material costs by manufacturing a heat exchanger with a compact structure by reducing the volume of tubes and fins, while maximizing thermal performance through a structure that minimizes refrigerant differential pressure.

[0022] The present invention has been devised to solve the above-mentioned problem, and the objective of the present invention is to provide a heat exchanger with a compact structure that reduces raw material costs by reducing the volume of tubes and fins.

[0023] Another objective of the present invention is to provide a heat exchanger that maximizes thermal performance through a structure in which the refrigerant differential pressure is minimized.

[0024] Another objective of the present invention is to provide a heat exchanger that maximizes heat exchanger performance by applying a louver structure optimized for a fin shape and a differential tube structure that minimizes refrigerant differential pressure.

[0025] Another objective of the present invention is to provide a heat exchanger with reduced cost by forming a tube having a width smaller than the fin width.

[0026] Another objective of the present invention is to provide a heat exchanger that achieves cost reduction in a limited installation space by reducing the volume of tubes, which have a high heat transfer coefficient and are less affected by performance degradation due to a reduction in the heat transfer surface area, and by reducing the volume of tubes that consume a large amount of material.

[0027] Another objective of the present invention is to provide a heat exchanger configured to reduce the volume of the tubes while maintaining the volume of the fins, thereby preventing dust clogging or an increase in material costs.

[0028] To solve the above problem, the heat exchanger of the present invention comprises: a first header to which an inlet pipe and a discharge pipe are connected; a second header spaced apart from the first header at a predetermined distance; a plurality of tubes arranged horizontally between the first header and the second header and each tube containing a plurality of micro-channels through which refrigerant flows; and a fin coupled to the outer surface of the tube in parallel with the direction of air flow, wherein the width of the tube facing the first header and the second header is formed to be smaller than the width of the fin.

[0029] As a result, the present invention can reduce the raw material costs of the heat exchanger by reducing the volume of the tubes and fins to produce a heat exchanger with a compact structure.

[0030] According to one example related to the present invention, the fin is formed in a wavy plate shape including a curved portion and includes a louver for air flow.

[0031] Therefore, the airflow passing over the fins is disrupted by the louvers, and the boundary layer does not grow, so the heat exchange efficiency can be increased.

[0032] The above tube is eccentrically positioned on the front side of the fin into which air enters.

[0033] In addition, the above tube is eccentrically positioned on the rear side of the fin through which air exits.

[0034] In addition, the tube is positioned on the center side of the pin.

[0035] According to another example related to the present invention, the tube comprises: at least one first tube disposed in a first range adjacent to the inlet pipe and through which a superheated steam refrigerant flows; and at least one second tube disposed in a second range adjacent to the discharge pipe and through which a subcooled liquid refrigerant flows.

[0036] The above refrigerant is introduced into the inlet pipe and flows from the first tube to the second tube.

[0037] Preferably, the width of the second tube is formed to be smaller than the width of the first tube, thereby reducing the refrigerant differential pressure between the inlet tube and the discharge tube.

[0038] As a result, the second tube of the present invention reduces the amount of pressure drop that occurs when the width is reduced compared to the first tube. This reduces the refrigerant differential pressure at the inlet and outlet sides of the heat exchanger, thereby enabling the heat exchange performance to be maintained smoothly.

[0039] According to another example related to the present invention, the width of the first tube is the same as the width of the second tube.

[0040] In this case, the first tube comprises a plurality of first microchannels, and the second tube comprises a plurality of second microchannels, and the number of the second microchannels is greater than the number of the first microchannels.

[0041] In addition, the size of the hole in the first microchannel is formed to be larger than the size of the hole in the second microchannel, thereby reducing the refrigerant differential pressure between the inlet pipe and the discharge pipe.

[0042] This disperses the liquid refrigerant flowing through the second microchannel, thereby allowing the thickness of the liquid film formed on the wall of the hole to be thin. When the thickness of the liquid film is reduced, the number of heat transfers inside the microchannel can be improved.

[0043] The first tube comprises a plurality of first microchannels, and the second tube comprises the same number of second microchannels as the first microchannels.

[0044] Preferably, the second microchannel is in the shape of a groove tube including a heat transfer projection protruding inwardly into the hole.

[0045] The above-mentioned heating projection includes a first heating projection protruding inward from the upper surface of the hole; and a second heating projection protruding inward from the lower surface of the hole, wherein the first heating projection and the second heating projection are arranged offset from each other.

[0046] Preferably, the second heating protrusions are formed in a greater number than the first heating protrusions.

[0047] This configuration disperses the liquid film concentrated downward by condensation, and allows the liquid film at the shear portion (upper) of the heat transfer protrusion to be kept thin.

[0048] In addition, the difference in the number of the first heating protrusion and the second heating protrusion is an odd number.

[0049] The second microchannel includes a guide groove formed between the second heat transfer protrusion and an adjacent second heat transfer protrusion to guide the flow of the refrigerant.

[0050] As a result, the guide groove forms a space where the refrigerant, which has undergone a phase change to a liquid state, sinks and collects due to the influence of gravity, thereby improving the flowability of the liquid refrigerant, improving the flow of the refrigerant moving toward the second header, and increasing the high dryness maintenance time of the tube.

[0051] In addition, the above-mentioned shear projection has an elliptical shear section having a constant curvature.

[0052] The curvature of this shear section (314a) causes the thickness of the liquid film to be formed thinly, thereby reducing the thermal resistance of the liquid film.

[0053] A heat exchanger according to another embodiment of the present invention comprises: a first header to which an inlet pipe and a discharge pipe are connected; a second header spaced apart from the first header at a predetermined distance; a plurality of tubes arranged horizontally between the first header and the second header, each tube including a plurality of micro-channels through which a refrigerant flows; and a fin coupled to the outer surface of the tubes parallel to the direction of air flow, wherein the tubes include a first tube positioned in a first range adjacent to the inlet pipe; and a second tube positioned in a second range adjacent to the discharge pipe, wherein the width of the second tube is formed to be smaller than the width of the first tube.

[0054] The width of the first tube is the same as the width of the pin.

[0055] In addition, the width of the second tube is formed to be smaller than the width of the pin.

[0056] As a result, the refrigerant differential pressure at the inlet and outlet sides of the heat exchanger is reduced, thereby preventing a decrease in heat exchange performance caused by the refrigerant differential pressure and ensuring that heat exchange performance is maintained smoothly.

[0057] The heat exchanger of the present invention has the advantage of reducing raw material costs by manufacturing a heat exchanger with a compact structure by reducing the volume of tubes and fins.

[0058] The present invention differs from conventional technology in that it maximizes thermal performance through a structure in which the refrigerant differential pressure is minimized.

[0059] The present invention has the effect of maximizing heat exchanger performance by applying a louver structure optimized for a fin shape and a differential tube structure that minimizes refrigerant differential pressure.

[0060] In addition, the present invention reduces costs by forming a tube having a width smaller than the pin width.

[0061] The present invention has the advantage of achieving cost reduction in a limited installation space by reducing the volume of tubes, which have a high heat transfer coefficient and are less affected by performance degradation due to a reduction in the heat transfer surface area, and by reducing the volume of tubes that consume a large amount of material.

[0062] In addition, the present invention is configured to reduce the volume of the tube while maintaining the volume of the fin, thereby having the effect of preventing dust clogging or an increase in material costs.

[0063] FIG. 1 is a perspective view illustrating the overall configuration of a heat exchanger according to the present invention.

[0064] FIG. 2 is a partially enlarged view illustrating the detailed configuration of a tube and a pin according to the present invention.

[0065] FIG. 3 is a front view of a heat exchanger according to the present invention.

[0066] FIG. 4 is a first side view illustrating the configuration of a tube and a fin according to a first embodiment of the present invention (an embodiment in which the tube is positioned on the center side of the fin).

[0067] FIG. 5 is a second side view illustrating the configuration of a tube and a fin according to a first embodiment of the present invention (an embodiment in which the tube is positioned on the front side of the fin).

[0068] FIG. 6 is a third side view illustrating the configuration of a tube and a fin according to a first embodiment of the present invention (an embodiment in which the tube is positioned on the rear side of the fin).

[0069] FIG. 7(a) is a first side view illustrating the configuration of the first tube and pin according to the second embodiment.

[0070] FIG. 7(b) is a first side view illustrating the configuration of a second tube and a pin according to a second embodiment (the second tube is positioned on the front side of the pin).

[0071] FIG. 8(a) is a second side view illustrating the configuration of the first tube and pin according to the second embodiment.

[0072] FIG. 8(b) is a second side view illustrating the configuration of a second tube and a pin according to a second embodiment (the second tube is positioned on the center side of the pin).

[0073] FIG. 9 is a side view illustrating the configuration of the first tube according to the third embodiment.

[0074] FIG. 10 is a side view illustrating the configuration of a second tube according to a third embodiment.

[0075] FIG. 11(a) is a side view illustrating the configuration of the first tube according to the fourth embodiment.

[0076] FIG. 11(b) is a side view illustrating the configuration of a second tube according to a fourth embodiment.

[0077] FIG. 12(a) is a cross-sectional view illustrating a state in which the heat transfer protrusions are arranged facing each other.

[0078] FIG. 12(b) is a cross-sectional view illustrating the configuration of a heat transfer protrusion according to the fourth embodiment.

[0079] FIG. 13 is a cross-sectional view illustrating the configuration of the heat transfer protrusion and the upper liquid film according to the fourth embodiment.

[0080] FIG. 14 is a perspective view illustrating the detailed configuration of a pin according to the present invention.

[0081] FIG. 15(a) is a first side view illustrating the configuration of the first tube and fin of a heat exchanger according to another embodiment of the present invention.

[0082] FIG. 15(b) is a first side view illustrating the configuration of the second tube and fin of a heat exchanger according to another embodiment of the present invention.

[0083] FIG. 16(a) is a second side view illustrating the configuration of the first tube and fin of a heat exchanger according to another embodiment of the present invention.

[0084] FIG. 16(b) is a second side view illustrating the configuration of the second tube and fin of a heat exchanger according to another embodiment of the present invention.

[0085] Hereinafter, a heat exchanger (1) related to the present invention will be described in more detail with reference to the drawings.

[0086] In this specification, identical or similar reference numbers are assigned to identical or similar configurations even for different embodiments, and redundant descriptions thereof are omitted.

[0087] In addition, even if the embodiments are different, as long as there is no structural or functional contradiction, the structure applied to one embodiment can be applied identically to another embodiment.

[0088] Singular expressions include plural expressions unless the context clearly indicates otherwise.

[0089] In describing the embodiments disclosed in this specification, if it is determined that a detailed description of related prior art could obscure the essence of the embodiments disclosed in this specification, such detailed description is omitted.

[0090] The attached drawings are intended only to facilitate understanding of the embodiments disclosed in this specification, and the technical concept disclosed in this specification is not limited by the attached drawings; it should be understood that all modifications, equivalents, and substitutions included within the concept and technical scope of the present invention are included.

[0091] FIG. 1 is a perspective view illustrating the overall configuration of a heat exchanger according to the present invention, FIG. 2 is a partially enlarged view illustrating the detailed configuration of tubes and fins according to the present invention, and FIG. 3 is a front view of a heat exchanger according to the present invention.

[0092] Referring to FIGS. 1 to 3, the heat exchanger (1) according to the present invention includes a first header (100), a second header (200), a tube (300), and a fin (400).

[0093] The first header (100) is positioned vertically.

[0094] The first header (100) is spaced apart from the second header (200) at a certain distance.

[0095] The first header (100) is connected to an inlet pipe (110) and an outlet pipe (120).

[0096] The inlet pipe (110) introduces a refrigerant. In this case, the refrigerant may be in a superheated steam state at high temperature and high pressure.

[0097] As an example, the inlet pipe (110) may be positioned above the first header (100).

[0098] The inlet pipe (110) may be placed on the lower side of the first header (100).

[0099] The discharge pipe (120) is a pipe through which the refrigerant, having completed heat exchange while passing through the tube (300), is discharged.

[0100] The refrigerant discharged through the discharge pipe (120) may be in a low-temperature, high-pressure supercooled liquid state.

[0101] As an example, the discharge pipe (120) may be positioned below the first header (100).

[0102] The discharge pipe (120) may be positioned on the upper side of the first header (100).

[0103] The second header (200) is spaced apart from the first header (100) by a predetermined distance and is positioned vertically.

[0104] On the mutually facing surfaces of the first header (100) and the second header (200), a tube coupling portion (not shown) is formed by cutting to a size corresponding to the cross-section of the tube (300) to which the tube (300) is joined.

[0105] The first header (100) and the second header (200) may each include a front tank (not shown) and a rear tank (not shown) separated by a bulkhead.

[0106] Although not shown, the front tank and rear tank can each be further divided vertically by baffles.

[0107] A tube (300) is installed between the first header (100) and the second header (200) to guide the refrigerant by connecting the first header (100) and the second header (200).

[0108] The tube (300) is arranged horizontally between the first header (100) and the second header (200).

[0109] The tube (300) is a passage through which the refrigerant passes.

[0110] The refrigerant circulates while being compressed or expanded inside the heat exchanger (1), enabling cooling and heating.

[0111] The tube (300) is arranged to pass through a plurality of fins (400) horizontally in the left-right direction of the heat exchanger (1), which is perpendicular to the direction of air flow.

[0112] When multiple fins (400) are arranged in an up-and-down direction along the direction of air flow, the tube (300) can also be bent and provided so as to cross multiple times along the direction of air flow.

[0113] The tube (300) includes a plurality of micro-channels (310) through which refrigerant flows.

[0114] The tube (300) is made using a metal material with good thermal conductivity.

[0115] The microchannel (310) is etched into the tube (300) of the metal plate through chemical etching to have a characteristic length between 1 μm and 1 mm.

[0116] As an example, the tube (300) may be rectangular in shape.

[0117] Although not shown, the tube (300) has main inlet holes (not shown) formed on both sides for the entry and exit of fluid. The main inlet holes (not shown) are divided into an inlet hole (not shown) and an outlet hole (not shown).

[0118] The microchannel (310) connects the main entrance / exit holes (not shown) on both sides and forms a channel.

[0119] In this case, the length of the microchannel (310) is connected in a straight line.

[0120] Although not shown, the microchannel (310) may be formed in a curved shape to extend beyond the length of a straight connection. Forming it in this curved shape increases the length of the heat exchange, thereby improving the heat exchange performance.

[0121] The heat exchanger (1) is a device installed in a limited space, and requires a compact structure to reduce the limited installation space and costs.

[0122] In the composition of the heat exchanger (1), the weight of the tube (300) accounts for more than 60%. Therefore, in order to reduce the cost of the heat exchanger (1) and to realize a compact structure, it may be efficient to reduce the amount of tube (300), which has a large proportion of material costs.

[0123] In contrast, a fin (400) with a low convective heat transfer coefficient has a significant impact on the performance of the heat exchanger (1). That is, the heat transfer surface area of ​​the fin (400) has a significant impact on the performance of the heat exchanger (1).

[0124] Accordingly, the heat exchanger (1) according to the present invention is configured to reduce the size of the tube (300) while maintaining the heat transfer area of ​​the fin (400). That is, the heat exchanger (1) can be configured compactly, and high-efficiency heat exchange performance can be achieved without reducing heat exchange performance.

[0125] Hereinafter, the configuration of the tube (300) according to the first embodiment will be described.

[0126] FIG. 4 is a first side view illustrating the configuration of a tube and a fin according to a first embodiment of the present invention (an embodiment in which the tube is positioned on the center side of the fin), FIG. 5 is a second side view illustrating the configuration of a tube and a fin according to a first embodiment of the present invention (an embodiment in which the tube is positioned on the front side of the fin), and FIG. 6 is a third side view illustrating the configuration of a tube and a fin according to a first embodiment of the present invention (an embodiment in which the tube is positioned on the rear side of the fin).

[0127] Referring to FIGS. 4 to 6, in the first embodiment, the tube (300) is formed such that the width (Wt) of the tube (300) facing the first header (100) and the second header (200) is smaller than the width (Wp) of the pin (400). (Wt < Wp)

[0128] The tube (300) is formed in a narrow shape with a small width and a thin height.

[0129] This reduces the use of tubes (300), which have a relatively high heat transfer coefficient, so that performance degradation due to the reduction in heat transfer surface area is less severe, while also reducing the amount of material consumed.

[0130] In contrast, the size of the fin (400), which has a low heat transfer coefficient and is significantly affected by performance degradation due to the reduction in heat transfer surface area, is manufactured without change. By maintaining the usage (size) of the fin (400), dust clogging or an increase in material costs can be prevented.

[0131] A certain portion of the pin (400) is made to protrude outward by a tube (300) having a width smaller than the width (Wp) of the pin (400).

[0132] Referring to FIG. 4, the tube (300) can be positioned at the center of the pin (400).

[0133] Referring to FIG. 5, the tube (300) may be eccentrically positioned on the front side of the fin (400) into which air is introduced.

[0134] Referring to FIG. 6, the tube (300) may be eccentrically positioned on the rear side of the fin (400) through which air is discharged.

[0135] That is, the pin (400) can protrude forward, backward, or in both directions relative to the tube (300).

[0136] Among the three embodiments described above, the embodiment in which the tube (300) is positioned at the center of the fin (400) and the fin (400) protrudes a predetermined range in both the front and rear directions may be somewhat superior in terms of reliability. That is, when the tube (300) is positioned at the center of the fin (400), the heat conduction between the tube (300) and the fin (400) can be implemented most efficiently.

[0137] Hereinafter, the configuration of the tube (300) according to the second embodiment will be described.

[0138] As described above, the heat exchanger (1) is formed with a compact structure to reduce installation space and costs, but problems such as reduced heat exchange performance, increased pressure loss on the refrigerant and air sides, and reduced product reliability must be overcome.

[0139] Accordingly, the heat exchanger (1) according to the present invention is configured to reduce the refrigerant differential pressure between the inlet pipe (110) (see FIG. 3) and the discharge pipe (120) (see FIG. 3) in order to solve the problem of reduced heat exchange performance and increased pressure loss of the compacted heat exchanger (1).

[0140] The refrigerant flowing in the upstream tube (300) of the heat exchanger (1), which is the inlet pipe (110) side, is superheated steam. Superheated steam has a high temperature and high pressure and a large specific volume.

[0141] In addition, the refrigerant in the downstream tube (300) of the heat exchanger (1), which is the discharge pipe (120) side, is heat-exchanged while flowing, causing the temperature and pressure to decrease, resulting in lower dryness and smaller specific volume. That is, the downstream refrigerant is in a low-temperature, high-pressure supercooled liquid state.

[0142] Generally, an air conditioner is divided into a condenser (not shown) and an evaporator (not shown).

[0143] The condenser (not shown) has a pressure difference of 100 kPa or less between the inlet and outlet, which may be a high-pressure state compared to the evaporator in a low-pressure state. Therefore, although there is a difference in that the refrigerant on the discharge pipe (120) side has a lower pressure than the refrigerant on the inlet pipe (110) side, it is expressed as a low-temperature, high-pressure state compared to the evaporator.

[0144] Additionally, during most of the process of the condenser, the internal refrigerant maintains its temperature and only undergoes a phase change from gas to liquid. Therefore, within the tube (300) adjacent to the discharge pipe (120), the liquid refrigerant maintains a relatively low temperature state compared to the inlet pipe (110), in a subcooled region where the temperature of the liquid refrigerant is lowered. Thus, the refrigerant on the discharge pipe (120) side (downstream side) can be described as a low-temperature, high-pressure subcooled liquid state.

[0145] As described above, a refrigerant differential pressure appears at the inlet and outlet of the heat exchanger (1). Since the pressure difference between the inlet and outlet of the heat exchanger (1) affects the reduction of heat quantity, it is necessary to minimize the pressure difference between the inlet and outlet to increase heat exchange performance.

[0146] FIG. 7(a) is a first side view illustrating the configuration of a first tube and a pin according to a second embodiment, FIG. 7(b) is a first side view illustrating the configuration of a second tube and a pin according to a second embodiment (the second tube is positioned on the front side of the pin), FIG. 8(a) is a second side view illustrating the configuration of a first tube and a pin according to a second embodiment, FIG. 8(b) is a second side view illustrating the configuration of a second tube and a pin according to a second embodiment (the second tube is positioned on the center side of the pin).

[0147] As a second embodiment, the tube (300) has a difference in width between the tube (300) positioned upstream of the heat exchanger (1) and the tube (300) positioned downstream.

[0148] Referring to FIGS. 7(a) to FIGS. 8(b), the tube (300) may be divided into a plurality of first tubes (320) placed in a first range adjacent to the inlet pipe (110) and a plurality of second tubes (330) placed in a second range adjacent to the discharge pipe (120).

[0149] The first tube (320) is positioned upstream of the heat exchanger (1).

[0150] The first tube (320) carries a superheated steam refrigerant.

[0151] That is, the refrigerant in the first tube (320) has a large specific volume.

[0152] The first range is the part where multiple first tubes (320) are stacked.

[0153] The second tube (330) is positioned downstream of the heat exchanger (1).

[0154] The second tube (330) carries a supercooled liquid refrigerant. As the superheated steam refrigerant flowing through the first tube (320) flows downstream, it changes into a supercooled liquid due to a drop in temperature and pressure.

[0155] That is, the refrigerant in the second tube (330) has a small specific volume.

[0156] The second range is the part where multiple second tubes (330) are stacked.

[0157] In the tube (300) according to the second embodiment, the width (Wt₂) of the second tube (330) is formed to be smaller than the width (Wt₁) of the first tube (320). (Wt₁ > Wt₂)

[0158] That is, the width (Wt₁) of the tube (300) on the inlet pipe (110) side (upstream side) of the heat exchanger (1) is formed wide, and the width (Wt₂) of the tube (300) on the discharge pipe (120) side (downstream side) is formed small.

[0159] The width of the tube (300) is applied differentially.

[0160] The second tube (330) has a reduced width compared to the first tube (320), thereby reducing the amount of pressure drop. This reduces the refrigerant differential pressure at the inlet and outlet sides of the heat exchanger (1).

[0161] Accordingly, the heat exchanger (1) of the present invention prevents a decrease in heat exchange performance due to refrigerant differential pressure, thereby ensuring that heat exchange performance is maintained smoothly.

[0162] Therefore, in the second embodiment, when comparing the widths of the pin (400), the first tube (320), and the second tube (330), it is summarized as follows.

[0163] "Width of pin > Width of 1st tube > Width of 2nd tube (Wp > Wt₁ > Wt₂)"

[0164] Hereinafter, the configuration of the tube (300) according to the third embodiment of the present invention will be described.

[0165] FIG. 9 is a side view illustrating the configuration of a first tube according to a third embodiment, and FIG. 10 is a side view illustrating the configuration of a second tube according to a third embodiment.

[0166] As a third embodiment, the tube (300) includes a first tube (320) of a first range and a second tube (330) of a second range.

[0167] The first range is a section adjacent to the inlet pipe (110) where the refrigerant of high temperature and high pressure superheated steam flows. The first range refers to the upstream side of the heat exchanger (1).

[0168] The second range is a section adjacent to the discharge pipe (120) where low-temperature, high-pressure supercooled liquid flows. The second range refers to the downstream side of the heat exchanger (1).

[0169] The first tube (320) and the second tube (330) have the same width (Wt₁= Wt₂).

[0170] That is, when comparing the widths of the pin (400), the first tube (320), and the second tube (330), it is summarized as follows.

[0171] "Width of pin > Width of 1st tube = Width of 2nd tube (Wp > Wt₁= Wt₂)"

[0172] Referring to FIGS. 9 and 10, the first tube (320) includes a plurality of first microchannels (311) inside, and the second tube (330) includes a plurality of second microchannels (312).

[0173] In addition, the number of second microchannels (312) is configured to be greater than the number of first microchannels (311).

[0174] Accordingly, the size of the hole (313) of the first microchannel (311) can be formed larger than the size of the hole (313) of the second microchannel (312). This can reduce the refrigerant differential pressure between the inlet pipe (110) and the discharge pipe (120) of the heat exchanger (1).

[0175] As the heat exchanger (1) moves downstream to the second range, the dryness of the refrigerant decreases, and the proportion of liquid refrigerant increases.

[0176] Accordingly, the second microchannel (312) included in the second tube (330) has a greater number of holes (313) than the number of holes (313) of the first microchannel (311). This disperses the liquid refrigerant flowing through the second microchannel (312), thereby allowing the thickness of the liquid film formed on the wall of the holes (313) to be thin. When the thickness of the liquid film is thin, the number of heat transfers inside the microchannel (310) is improved.

[0177] That is, in the third embodiment, the tube (300) is configured such that the number of holes (313) in the second microchannel (312) is greater than the number of holes (313) in the first microchannel (311), and the size of the holes (313) in the second microchannel (312) is smaller than the size of the holes (313) in the first microchannel (311), thereby reducing the refrigerant differential pressure on the inlet / outlet side of the heat exchanger (1).

[0178] Accordingly, the heat exchanger (1) of the present invention prevents a decrease in heat exchange performance due to refrigerant differential pressure, thereby ensuring that heat exchange performance is maintained smoothly.

[0179] Hereinafter, the configuration of the tube (300) according to the fourth embodiment of the present invention will be described.

[0180] FIG. 11(a) is a side view illustrating the configuration of a first tube according to a fourth embodiment, FIG. 11(b) is a side view illustrating the configuration of a second tube according to a fourth embodiment, FIG. 12(a) is a cross-sectional view illustrating a state in which heat transfer protrusions are arranged facing each other, FIG. 12(b) is a cross-sectional view illustrating the configuration of heat transfer protrusions according to a fourth embodiment, and FIG. 13 is a cross-sectional view illustrating the configuration of heat transfer protrusions and an upper liquid film according to a fourth embodiment.

[0181] As a fourth embodiment, the tube (300) includes a first tube (320) of a first range and a second tube (330) of a second range.

[0182] The first tube (320) and the second tube (330) have the same width (Wt₁= Wt₂).

[0183] That is, when comparing the widths of the pin (400), the first tube (320), and the second tube (330), it is summarized as follows.

[0184] Width of pin > Width of 1st tube = Width of 2nd tube (Wp > Wt₁= Wt₂)

[0185] The first tube (320) includes a plurality of first microchannels (311) inside, and the second tube (330) includes a plurality of second microchannels (312).

[0186] In addition, the first microchannel (311) and the second microchannel (312) are distributed in equal numbers.

[0187] Referring to FIG. 11(b), the second microchannel (312) includes a heat transfer projection (314) that protrudes into the hole (313).

[0188] That is, the second microchannel (312) is a grooved tube shape.

[0189] Referring to FIG. 11(a), the first microchannel (311) does not include a projection protruding into the hole (313).

[0190] That is, the first microchannel (311) has a smooth tube shape.

[0191] The heat transfer projection (314) is a projection that protrudes into the hole (313) of the second microchannel (312).

[0192] The refrigerant flowing through the tube (300) changes from a gaseous state to a liquid state. That is, the gaseous refrigerant introduced through the inlet pipe (110) condenses into a liquid state by heat exchange while flowing through the tube (300). In this case, the flow pattern of the refrigerant changes inside the microchannel (310).

[0193] When looking at changes in the flow pattern of the refrigerant, as the gaseous refrigerant condenses into the liquid phase, the annular flow of the refrigerant transitions into a stratified flow, such as a slug flow or a wavy flow.

[0194] Annular flow is observed in gaseous refrigerant velocity and liquid refrigerant flow.

[0195] Under gaseous and liquid flow conditions, the buoyancy effect tends to make the liquid thickness at the top of the channel wall thinner and the liquid thickness at the bottom thicker. However, at significantly high gaseous (gaseous refrigerant) flow velocities, the gaseous flow is always turbulent, and strong lateral Reynolds stress and shear forces due to secondary flow act to distribute the water (liquid, liquid refrigerant) more evenly around the channel, contrary to the gravitational tendency to stratify the flow.

[0196] In slug flow, the formation and destruction of waves at the interface occur simultaneously due to the high velocity of the gas phase in the context of wave flow. Additionally, at high flow velocities of the liquid phase, the amplitude of the waves increases, causing the liquid phase to form across the entire height of the channel and create large slug-shaped bubbles. Due to their buoyancy, air slugs flowing along the channel tend to be pushed toward the upper part of the channel.

[0197] Wavy flow is formed in a wave-like shape when the flow rate and velocity increase in a stratified flow region, causing the interface between the liquid and gas phases to be in an unstable state.

[0198] Refrigerants have a high heat transfer coefficient in annular flow. Therefore, it is efficient for the refrigerant to maintain the annular flow state for an extended period.

[0199] The heating protrusion (314) can increase the pressure difference inside the microchannel (310) to increase the power required by the compressor.

[0200] If a narrow, thin tube (300) is used, the cross-sectional area through which the refrigerant passes is reduced, and the differential pressure between the inlet and outlet of the heat exchanger (1) increases.

[0201] As it moves downstream to the second range, the dryness of the refrigerant decreases, and the proportion of liquid refrigerant increases. Therefore, the second tube (330) of the second range requires a heat transfer promoting structure.

[0202] The heat transfer protrusion (314) is a component of the heat transfer promoting structure.

[0203] The heating protrusion (314) strengthens the surface tension inside the second microchannel (312).

[0204] Referring to FIG. 13, the heat transfer protrusion (314) disperses the liquid film of the refrigerant and reduces the thickness of the liquid film, thereby reducing the thermal resistance of the liquid film.

[0205] In addition, the heat transfer protrusion (314) can disperse the liquid film of the refrigerant to prevent delay in the annular flow.

[0206] In addition, the heat transfer protrusion (314) has the advantage of increasing the heat transfer area within the tube (300), thereby improving heat transfer performance while maintaining a similar pressure loss.

[0207] That is, the heat transfer protrusion (314) maximizes the effect of improving the heat transfer area inside the microchannel (310), thereby improving heat exchange performance.

[0208] The heating protrusion (314) includes a first heating protrusion (314b) and a second heating protrusion (314c).

[0209] The first heat-transfer projection (314b) is a projection that protrudes into the interior of the hole (313) from the upper surface of the hole (313).

[0210] The second heat projection (314c) is a projection that protrudes from the lower surface of the hole (313) into the interior of the hole (313).

[0211] Referring to FIGS. 11 and 12, the first heat transfer projection (314b) and the second heat transfer projection (314c) are arranged offset from each other.

[0212] The heat transfer protrusion (314) is manufactured by extrusion. When the first heat transfer protrusion (314b) and the second heat transfer protrusion (314c) are arranged in an offset manner, the width of the die can be formed wide when using the extrusion die of the heat transfer protrusion (314).

[0213] Referring to FIG. 12(a) and FIG. 12(b), when the first heat transfer projection (314b) and the second heat transfer projection (314c) are arranged to face each other without misalignment, the spacing distance (ℓ₁) between the heat transfer projections (314) is smaller than the spacing distance (ℓ₂) between the heat transfer projections (314) and the corresponding surfaces when the first heat transfer projection (314b) and the second heat transfer projection (314c) are arranged misaligned. (ℓ₁ < ℓ₂)

[0214] That is, when the first heat transfer projection (314b) and the second heat transfer projection (314c) are arranged offset from each other, the width of the die can be formed wider when using the extrusion die of the heat transfer projection (314). This structure ensures that the first heat transfer projection (314b) and the second heat transfer projection (314c) are arranged so as not to interfere with each other, thereby increasing manufacturability and stability through extrusion.

[0215] In addition, by arranging the first heat transfer protrusion (314b) and the second heat transfer protrusion (314c) in an offset manner, a wide flow space for the refrigerant is secured. This secures space inside the microchannel (310), thereby improving the flow efficiency of the refrigerant.

[0216] The second heating protrusion (314c) is formed in greater numbers than the first heating protrusion (314b).

[0217] That is, the number of first heat-reducing protrusions (314b) and second heat-reducing protrusions (314c) is applied differentially.

[0218] In addition, the difference in the number of the first heating protrusion (314b) and the second heating protrusion (314c) is formed to be an odd number.

[0219] The first heat-reducing protrusions (314b) are arranged in an odd number (1, 3, 5 …) fewer than the second heat-reducing protrusions (314c).

[0220] For example, as shown in FIG. 11(b) and FIG. 12(b), the first heating projection (314b) may be formed as one and the second heating projection (314c) as two. Alternatively, although not shown, when the first heating projection (314b) is one, the second heating projection (314c) may be four or six.

[0221] Additionally, if there are two first heat transfer protrusions (314b), the second heat transfer protrusions (314c) may be formed as three or five.

[0222] In this case, the first heat transfer projection (314b) is positioned to correspond to the second heat transfer projection (314c).

[0223] An increase in the number of heat transfer protrusions (314) increases the heat transfer area within the microchannel (310) while slightly reducing the cross-sectional area. In other words, the heat transfer performance is improved.

[0224] A guide groove (314d) is formed between a plurality of second-order protrusions (314c).

[0225] The guide groove (314d) is a groove formed between the second row protrusion (314c) and the adjacent second row protrusion (314c).

[0226] The guide groove (314d) is a space where the refrigerant, which has undergone a phase change to a liquid state, settles and collects due to the influence of gravity.

[0227] The guide groove (314d) improves the flowability of the liquid refrigerant, thereby improving the flow of the refrigerant moving toward the second header (200).

[0228] Therefore, the guide groove (314d) increases the high dryness retention time of the tube (300).

[0229] In an abnormal flow where liquid and gas phases coexist, the microchannel (310) maintains internal flow in the form of an annular flow surrounding the inner surface of the liquid film hole. At this time, at a specific dryness level, the liquid phase may concentrate towards the bottom surface due to gravity. The liquid film acts as a thermal resistance inside the microchannel (310). This is because the liquid film has a lower thermal conductivity than the microchannel (310) composed of metal, thereby increasing thermal resistance.

[0230] Accordingly, the heat transfer protrusions (314) are formed protruding from the lower part of the hole where the liquid film is relatively thick, thereby facilitating the action of penetrating the liquid film and directly exchanging heat with the gaseous refrigerant, which can enhance heat exchange. Additionally, by forming the second heat transfer protrusions (314c) in greater numbers than the first heat transfer protrusions (314b), the heat exchange performance can be further improved.

[0231] In addition, by forming the second heat transfer protrusion (314c) more than the first heat transfer protrusion (314b), the liquid film concentrated downward by condensation is dispersed, and the liquid film at the shear portion (upper) of the heat transfer protrusion (314) can be kept thin.

[0232] The shear projection (314) has an elliptical shear portion (314a) with a constant curvature.

[0233] It may be preferable for the shear portion (314a) of the shear projection (314) to have a certain curvature.

[0234] Specifically, the shear portion (314a) of the shear projection (314) has a curvature positioned at the shear of the major axis vertex of the ellipse. That is, the angle of inclination of the shear portion (314a) increases significantly as it approaches the center.

[0235] Referring to FIG. 13, the curvature of this shear section (314a) allows the thickness of the liquid film to be formed thinly.

[0236] This reduces the thermal resistance of the liquid film.

[0237] Meanwhile, the heating protrusion (314) may be provided in both the first microchannel (311) and the second microchannel (312).

[0238] FIG. 14 is a perspective view illustrating the detailed configuration of a pin according to the present invention.

[0239] Referring to FIG. 14, the fin (400) is coupled to the outer surface of the tube (300) parallel to the direction of air flow.

[0240] The heat exchanger (1) may include a plurality of fins (400).

[0241] The fin (400) contacts the outer surface of the tube (300) to facilitate heat exchange between the refrigerant flowing inside the tube (300) and the air passing through the heat exchanger (1). The heat of the refrigerant flowing inside the tube (300) is transferred to the air flowing around the tube (300) and the fin (400) and is easily dissipated to the outside.

[0242] Conversely, the same applies when the heat of the air flowing around the fin (400) is transferred to the refrigerant through the fin (400) and the tube (300).

[0243] That is, the heat exchanger (1) can be defined as including fins (400), tubes (300), and ducts (not shown) that are directly related to the generation of cold air.

[0244] The pin (400) can be made of various metal materials, including aluminum, which has high thermal conductivity.

[0245] Referring to FIG. 2 and FIG. 14, the pin (400) is formed in the shape of a plate with a wavy section.

[0246] The plate includes louvers (410) for air flow.

[0247] Accordingly, the fins (400) can be arranged to be spaced apart in the left and right directions of the heat exchanger (1), which is perpendicular to the direction of air flow.

[0248] The narrower the spacing of the fins (400), the more fins (400) can be arranged, but if the spacing becomes too narrow, it acts as resistance to the air passing through the heat exchanger (1), and there is a concern for pressure loss, so it is necessary to adjust the spacing appropriately.

[0249] Louvers (410) are arranged parallel to each other at regular intervals, parallel to the direction of air flow. As a result, slits (430) are formed between the louvers (410).

[0250] Therefore, air can flow naturally across the surface of the fin (400) without receiving significant resistance from the fin and can exchange heat.

[0251] The louvers (410) are arranged such that the direction of the front louvers (410) into which wind (air) enters and the rear louvers (410) into which wind exits are mutually symmetrical. Additionally, the plates of the fins (400) forming a wave shape are formed at a predetermined angle. Therefore, the flow of air passing over the fins (400) is disrupted by the louvers (410), and the boundary layer does not grow, so the heat exchange efficiency can be further increased.

[0252] Hereinafter, a heat exchanger according to another embodiment of the present invention will be described.

[0253] FIG. 15(a) is a first side view illustrating the configuration of a first tube and fin of a heat exchanger according to another embodiment of the present invention, FIG. 15(b) is a first side view illustrating the configuration of a second tube and fin of a heat exchanger according to another embodiment of the present invention, FIG. 16(a) is a second side view illustrating the configuration of a first tube and fin of a heat exchanger according to another embodiment of the present invention, and FIG. 16(b) is a second side view illustrating the configuration of a second tube and fin of a heat exchanger according to another embodiment of the present invention.

[0254] In another embodiment, the heat exchanger (1) includes a first tube (320) positioned in a first range adjacent to an inlet pipe (110) and a second tube (330) positioned in a second range adjacent to an outlet pipe (120).

[0255] As illustrated in FIGS. 15(a) and FIGS. 16(a), the first tube (320) is formed with a width equal to the width of the pin (400). That is, the width (Wt₁) of the first tube (320) is equal to the width (Wp) of the pin (400). (Wt₁ = Wp)

[0256] As shown in FIGS. 15(b) and FIGS. 16(b), the width (Wt₂) of the second tube (330) is formed to be smaller than the width (Wt₁) of the first tube (320). (Wt₁ > Wt₂)

[0257] Therefore, the width (Wt₂) of the second tube (330) is formed to be smaller than the width (Wp) of the pin (400). (Wt₂ < Wp)

[0258] That is, when comparing the widths of the pin (400), the first tube (320), and the second tube (330), it is summarized as follows.

[0259] "Fin width = Width of 1st tube > Width of 2nd tube (Wp = Wt₁ > Wt₂)"

[0260] Accordingly, in the heat exchanger (1) according to another embodiment, the width of the tube (300) on the inlet pipe (110) side (upstream side) is the same as the width of the fin (400), but the width of the tube (300) on the discharge pipe (120) side (downstream side) is formed to be smaller than the width of the fin (400).

[0261] That is, the width of the tube (300) is applied differentially.

[0262] The second tube (330) has a reduced width compared to the first tube (320), thereby reducing the amount of pressure drop. This reduces the refrigerant differential pressure at the inlet and outlet sides of the heat exchanger (1).

[0263] Accordingly, the heat exchanger (1) of the present invention prevents a decrease in heat exchange performance due to refrigerant differential pressure, thereby ensuring that heat exchange performance is maintained smoothly.

[0264] The heat exchanger of the present invention has the advantage of reducing raw material costs by manufacturing a heat exchanger with a compact structure by reducing the volume of tubes and fins.

[0265] The present invention differs from conventional technology in that it maximizes thermal performance through a structure in which the refrigerant differential pressure is minimized.

[0266] The present invention has the effect of maximizing heat exchanger performance by applying a louver structure optimized for a fin shape and a differential tube structure that minimizes refrigerant differential pressure.

[0267] In addition, the present invention reduces costs by forming a tube having a width smaller than the pin width.

[0268] The present invention has the advantage of achieving cost reduction in a limited installation space by reducing the volume of tubes, which have a high heat transfer coefficient and are less affected by performance degradation due to a reduction in the heat transfer surface area, and by reducing the volume of tubes that consume a large amount of material.

[0269] In addition, the present invention is configured to reduce the volume of the tube while maintaining the volume of the fin, thereby having the effect of preventing dust clogging or an increase in material costs.

[0270] The heat exchanger (1) described above is not limited to the configuration and method of the embodiments described above, and all or part of each embodiment may be selectively combined to allow for various modifications to be made.

[0271] It is obvious to those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit and essential features of the invention. Accordingly, the foregoing detailed description should not be interpreted restrictively in all respects but should be considered exemplary. The scope of the invention shall be determined by a reasonable interpretation of the appended claims, and all modifications within the equivalent scope of the invention are included within the scope of the invention.

[0272] The present invention can be used in a heat exchanger.

Claims

1. A first header to which the inlet pipe and the discharge pipe are connected; A second header spaced apart from the first header above by a predetermined distance; A plurality of tubes arranged horizontally between the first header and the second header, each including a plurality of micro-channels through which refrigerant flows; and It includes a fin coupled to the outer surface of the above tube parallel to the direction of air flow, and The above tube is, A heat exchanger in which the width facing the first header and the second header is formed to be smaller than the width of the fin.

2. In Paragraph 1, The above pin is, A heat exchanger formed in a corrugated plate shape including a bend and including louvers for air flow.

3. In Paragraph 1, The above tube is, A heat exchanger eccentrically positioned on the front side of the fin where air enters.

4. In Paragraph 1, The above tube is, A heat exchanger eccentrically positioned at the rear side of the fin through which air exits.

5. In Paragraph 1, The above tube is, A heat exchanger positioned at the center of the above fin.

6. In Paragraph 1, The above tube is, At least one first tube disposed in a first range adjacent to the above-mentioned inlet pipe, through which a refrigerant of superheated steam flows; and A heat exchanger comprising at least one second tube disposed in a second range adjacent to the discharge pipe and through which a refrigerant of a supercooled liquid flows.

7. In Paragraph 6, The above refrigerant is, A heat exchanger that flows into the inlet pipe and from the first tube to the second tube.

8. In Paragraph 6, The width of the second tube above is, A heat exchanger formed to be smaller than the width of the first tube, thereby reducing the refrigerant differential pressure between the inlet pipe and the discharge pipe.

9. In Paragraph 6, The width of the first tube above is, A heat exchanger with the same width as the second tube above.

10. In Paragraph 9, The first tube above includes a plurality of first microchannels, and The second tube above includes a plurality of second microchannels, and A heat exchanger in which the number of the second microchannels is greater than the number of the first microchannels.

11. In Paragraph 10, The size of the hole in the first microchannel is, A heat exchanger formed larger than the size of the hole in the second microchannel above, thereby reducing the refrigerant differential pressure between the inlet pipe and the discharge pipe.

12. In Paragraph 9, The first tube above includes a plurality of first microchannels, and The above second tube is a heat exchanger comprising the same number of second microchannels as the first microchannel.

13. In Paragraph 12, The above second microchannel is, A heat exchanger having a groove tube shape including a heat transfer projection protruding inwardly into the hole.

14. In Paragraph 13, The above-mentioned heating protrusions are, A first heat transfer projection protruding inward from the upper surface of the above hole; and It includes a second heat transfer projection protruding inward from the lower surface of the above hole, and The first heat transfer protrusion and the second heat transfer protrusion are arranged offset from each other in a heat exchanger.

15. In Paragraph 14, The above second heating projection is, A heat exchanger formed with a greater number than the first heat transfer protrusions mentioned above.

16. In Paragraph 15, The difference in the number of the first heat transfer protrusions and the second heat transfer protrusions is, Odd-numbered individual heat exchangers.

17. In Paragraph 15, The above second microchannel is, A heat exchanger comprising a guide groove formed between the second heat transfer protrusion and an adjacent second heat transfer protrusion to guide the flow of refrigerant.

18. In Paragraph 13, The above-mentioned heating protrusions are, A heat exchanger having an elliptical shear section with a constant curvature.

19. A first header to which the inlet pipe and the discharge pipe are connected; A second header spaced apart from the first header above by a predetermined distance; A plurality of tubes arranged horizontally between the first header and the second header, each including a plurality of micro-channels through which refrigerant flows; and It includes a fin coupled to the outer surface of the above tube parallel to the direction of air flow, and The above tube is, A first tube disposed in a first range adjacent to the above-mentioned inlet pipe; and It includes a second tube disposed in a second range adjacent to the discharge pipe, and A heat exchanger in which the width of the second tube is formed to be smaller than the width of the first tube.

20. In Paragraph 19, The width of the first tube above is, A heat exchanger with the same width as the above fins.

21. In Paragraph 19, The width of the second tube above is, A heat exchanger formed with a width smaller than the above fin.

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