HK1173210A - Heat transfer tube for heat exchanger, heat exchanger, refrigeration cycle device, and air conditioning device - Google Patents

Description

Heat transfer tube for heat exchanger, refrigeration cycle device, and air conditioning device

Technical Field

The present invention relates to a heat transfer tube for a heat exchanger having a groove formed on the inner surface of the tube, a heat exchanger, a refrigeration cycle apparatus, and an air conditioner.

Background

Conventionally, in a heat exchanger used in a refrigeration apparatus, an air conditioning apparatus, a heat pump, or the like, generally, through holes are provided in a plurality of fins arranged in parallel at a predetermined interval, and a heat transfer pipe having a groove formed in an inner surface thereof is disposed in the through holes. The heat transfer pipe is a part of a refrigerant circuit in the refrigeration cycle apparatus, and a refrigerant (fluid) flows inside the pipe.

The grooves in the inner surface of the tube are formed so that the direction of the tube axis forms an angle with the direction in which the grooves extend. Here, the grooves form the concave and convex portions on the inner surface of the pipe, and the space of the concave portion is defined as a groove portion, and the convex portion formed by the side wall of the adjacent groove is referred to as a ridge portion.

The refrigerant flowing through the heat transfer tubes undergoes a phase change (condensation or evaporation) by heat exchange with air or the like outside the heat transfer tubes. In order to efficiently perform this phase change, the heat transfer performance of the heat transfer tube is improved by increasing the surface area in the tube, the fluid agitation effect of the groove portions, the liquid film holding effect between the groove portions due to the capillary action of the groove portions, and the like (for example, see patent document 1).

Documents of the prior art

Patent document 1: japanese laid-open patent publication No. Sho 60-142195 (page 2, FIG. 1)

The heat transfer tube of patent document 1 described above is generally made of a metal such as copper or a copper alloy. In the manufacture of the heat exchanger, a mechanical tube expansion method is employed in which a tube expansion ball is pressed into the tube to expand the heat transfer tube from the inside, and the fin and the heat transfer tube are brought into close contact and joined together. However, when expanding the tube, the crests are pressed down by the tube expansion balls, which lowers the close contact between the heat transfer tube and the fins, and also increases the pressure loss in the tube, which lowers the heat transfer performance.

Disclosure of Invention

The present invention has been made to solve the above-described problems, and an object thereof is to provide a heat transfer tube for a heat exchanger, a heat exchanger using the heat transfer tube, a refrigeration cycle apparatus using the heat exchanger, and an air conditioner using the refrigeration cycle apparatus, which can improve the close contact between the heat transfer tube and fins and obtain a predetermined heat transfer performance without increasing the loss of pressure in the tube.

In the heat transfer tube for a heat exchanger of the present invention, a peak and a lower peak lower than the peak are spirally provided at a predetermined height along the tube axis direction of the tube inner surface, 11 to 19 peaks are formed at the peak, 3 to 6 peaks are formed between the peaks, the peak is in a cross-sectional trapezoidal shape in which the peak top is planar before the tube expansion, and the ratio of the top width of the peak top portion after the tube expansion to the outer diameter of the heat transfer tube is 0.011 to 0.040.

The heat exchanger according to the present invention is the heat transfer tube described in any of the above-described embodiments including the plurality of fins for performing heat exchange and the penetrating fins, and the heat transfer tube is expanded by applying pressure from the inner surface side of the heat transfer tube, and the fins are joined to the heat transfer tube.

In the refrigeration cycle apparatus of the present invention, a refrigerant circuit for circulating a refrigerant is configured by connecting a compressor for compressing the refrigerant, a condenser for condensing the refrigerant by heat exchange, an expansion mechanism for decompressing the condensed refrigerant, and an evaporator for evaporating the decompressed refrigerant by heat exchange, by pipes, and the heat exchanger described in any one of the above-described embodiments is provided in both or either one of the condenser and the evaporator.

In addition, the air conditioner of the present invention performs cooling and heating of the target space by the refrigeration cycle device.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the heat transfer tube for a heat exchanger of the present invention, when the heat transfer tube is expanded by the mechanical tube expansion method, the expansion ball comes into contact with the peak and the peak portion is crushed and flattened, but the peak portion is not crushed, and the heat transfer performance in the tube can be improved without increasing the pressure loss as compared with the conventional heat transfer tube. In addition, the outer surface of the heat transfer tube is processed into a polygonal shape, so that springback of the heat transfer tube can be suppressed, and the close contact between the heat transfer tube and the fins can be improved.

Further, the heat transfer tube can be used to provide a heat exchanger, a refrigeration cycle device, and an air conditioner having high efficiency.

Drawings

Fig. 1 is a perspective view of a heat exchanger according to embodiment 1 of the present invention, and a side sectional view of the heat exchanger cut in parallel with a fin surface.

Fig. 2 is an enlarged cross-sectional view of the heat transfer pipe at section a of fig. 1 before and after expansion.

Fig. 3 is an explanatory diagram showing an expanded state of the heat transfer pipe of fig. 1 in a mechanical tube expansion method.

Fig. 4 is a graph showing the relationship between the number of peaks of the heat transfer tubes and the heat exchange rate in embodiment 1.

Fig. 5 is a diagram showing the relationship between the heat exchange rate and the ratio between the tip width of the peak and the outer diameter of the heat transfer pipe after expansion of the heat transfer pipe in embodiment 1.

Fig. 6 is a cross-sectional view showing the shape of the inner surface of the heat transfer pipe after expansion according to embodiment 2 of the present invention.

Fig. 7 is a diagram showing the relationship between the difference between the groove and the crest and the heat exchange rate after expansion of the heat transfer pipe of embodiment 2.

Fig. 8 is a front sectional view of the inner surface of the tube of the heat transfer tube according to embodiment 3 of the present invention.

Fig. 9 is a diagram showing the relationship between the lead angle of the spiral groove of the heat transfer pipe and the heat exchange rate in embodiment 3.

Fig. 10 is a cross-sectional view showing the inner surface shape of the heat transfer tube according to embodiment 4 of the present invention.

Fig. 11 is a graph showing the relationship between the apex angle of the peak of the heat transfer tube and the heat exchange rate in embodiment 4.

Fig. 12 is a system circuit diagram of an air conditioner according to embodiment 5 of the present invention.

Detailed Description

Embodiment mode 1

In fig. 1, a heat exchanger 1 is a fin-and-tube heat exchanger widely used as an evaporator and a condenser of a refrigeration apparatus, an air-conditioning apparatus, and the like.

The heat exchanger 1 is constituted by a plurality of heat exchanger fins 10 and heat transfer tubes 20. Each of the plurality of fins 10 arranged in parallel at a predetermined interval is provided with a through hole 11, and the heat transfer pipe 20 penetrates the through hole 11. The heat transfer tube 20 is a part of a refrigerant circuit in the refrigeration cycle apparatus, and heat of the refrigerant flowing inside the heat transfer tube 20 and the air flowing outside is transferred through the fins 10, whereby the heat transfer area is increased, and heat exchange between the refrigerant and the air is efficiently performed.

As shown in fig. 2, the inner surface of the heat transfer tube 20 is provided with grooves 21 and crests 22 by forming the grooves, and as shown in fig. 2, the crests 22 are constituted by two crests, i.e., crests 22a and troughs 22 b. A plurality of low peaks 22b are formed between the high peaks 22a, the high peaks 22a are formed in a flat cross-sectional trapezoidal shape at the peak top before expansion (FIG. 2 (b)), and the ratio W1/D of the peak top width W1 to the outer diameter D of the heat transfer tube 20 after expansion (FIG. 2 (a)) is 0.011 to 0.040. The height t1 of the low peak 22b before expansion is 0.04mm or more lower than the height t2 of the high peak 22a by t 3. However, since the thermal performance may be degraded due to a decrease in the surface area in the tube when the difference between the high peak 22a and the low peak 22b is too large (the low peak 22b is too small), the difference is close to 0.04mm in the present embodiment.

In fig. 3, in the heat exchanger 1, first, a plurality of capillaries to be the heat transfer tube 20 are formed, and the plurality of capillaries are bent at a predetermined bending pitch in the central portion in the longitudinal direction to be formed into a hairpin shape. Next, after the capillary tube is inserted into the through hole 11 of the fin 10, the capillary tube is expanded mechanically to form the heat transfer tube 20, and the heat transfer tube 20 is joined to the fin 10 in close contact therewith. The mechanical tube expansion method is a method of causing a rod 31 having a tube expansion ball 30 at the tip end thereof, which has a diameter slightly larger than the inner diameter of the heat transfer tube 20, to pass through the inside of the heat transfer tube 20 to expand the outer diameter of the heat transfer tube 20 and thereby to be brought into close contact with the fins 10.

When the pipe is expanded by the mechanical pipe expansion method, the expansion ball 30 contacts, so that the peak top portion of the peak 22a is crushed to be flat, and the peak height becomes low. On the other hand, the low peak 22b is not deformed because the peak top is lower than the crush height by 0.04m (see fig. 2). Further, as in the conventional art, since the pressure for inserting the expansion ball 30 is not applied to all the crests in the tube and the tube is expanded by applying the pressure only to the portion of the crest 22a, the outer surface of the heat transfer tube 20 is processed into a polygonal shape, and the springback of the heat transfer tube 20 can be suppressed. This improves the close contact between the heat transfer tube 20 and the fins 10, and improves the heat exchange efficiency.

Fig. 4 shows the relationship between the number of the peaks 22a and the heat exchange rate, and 11 to 19 peaks 22a are formed continuously in a spiral shape in the axial direction on the inner surface of the heat transfer tube 20, and 3 to 6 peaks 22b are formed between the peaks 22a and the peaks 22 a.

In this way, in the heat exchanger 1, the reason why the high peaks 22a of the heat transfer tubes 20 are set to be in the range of 11 to 19 is that, during expansion, the expansion balls 30 are in contact with the high peaks 22a, the peak top portions are crushed by about 0.04mm, flattened, and the peak heights are lowered, but when the number of the high peaks 22a of the heat transfer tubes 20 is less than 11, the peak top portions of the low peaks 22b are also crushed and flattened, and the in-tube heat transfer performance is lowered. When the number of the high peaks is larger than 19, the number of the low peaks 22b decreases, and the heat transfer performance in the tube decreases.

In the expanded heat transfer tube 20, the ratio W1/D of the peak width W1 of the peak portion of the peak 22a to the outer diameter D of the heat transfer tube 20 is 0.011 to 0.040 (see fig. 2).

Fig. 5 shows the relationship between the heat exchange rate and the ratio W1/D of the tip width W1 of the peak 22a to the outer diameter D of the heat transfer tube 20 after expansion, and when the ratio W1/D of the tip width W1 to the outer diameter D of the heat transfer tube 20 after expansion is 0.011 or less, the peak top portion is crushed during expansion using the expansion ball 30, and the pressure generated by insertion is weakened. Therefore, the heat transfer tubes 20 are insufficiently expanded, the close contact between the heat transfer tubes 20 and the fins 10 is deteriorated, and the heat exchange rate is remarkably reduced. When the ratio W1/D between the distal end width W1 and the outer diameter D of the heat transfer tube 20 is 0.040 or more, the cross-sectional area of the groove portion 21 decreases, and therefore the liquid film of the refrigerant becomes thick, and the heat conductivity significantly decreases.

On the other hand, when the radius of curvature R1 at the tip portion (peak top) of the low peak 22b is 0.03mm to 0.035mm, the width of the bottom of the peak becomes narrow and becomes narrow as a whole, thereby increasing the heat transfer area and improving the heat conductivity in the tube (see fig. 2).

The peak 22a has a cross-sectional trapezoidal shape in which the peak top is formed into a flat surface before the pipe expansion, and thus the pressure at the peak top is reduced and the amount of collapse at the peak top is reduced. However, if the respective radii of curvature of the flat surface of the crest portion and the two side surfaces are 0.01mm or less, the manufacturing cost of the heat transfer pipe 20 may increase. Therefore, the curvature radius of the plane of the peak top and the two side surfaces is preferably 0.01 to 0.03 mm.

As described above, according to the heat exchanger 1 of embodiment 1, the crests 22, which are formed of the high crests 22a and the low crests 22b, are formed in a spiral shape in the tube inner surface of the heat transfer tube 20 with respect to the tube axis direction, the high crests 22a are formed in a flat cross-sectional trapezoidal shape before expansion, the ratio W1/D of the crest width W1 of the crest portion after expansion to the outer diameter D of the heat transfer tube 20 is 0.011 to 0.040, and the crest curvature radius R1 of the low crests 22b, which are formed in a range of 3 to 6 rows between the high crests 22a and have a height lower than the high crests 22a, is 0.03mm to 0.045mm, so that the heat transfer performance of the heat transfer tube 20 can be improved. Further, since the tube expansion balls 30 expand while contacting only the peaks 22a, the outer surface of the heat transfer tube 20 is formed into a polygonal shape, so that springback of the heat transfer tube 20 can be suppressed, the close contact between the heat transfer tube 20 and the fins 10 can be improved, and the heat exchange rate (the ratio of heat before and after the heat transfer tube passes) can be improved, thereby achieving energy saving. In addition, the amount of refrigerant in the refrigerant circuit can be reduced, and downsizing can be achieved while maintaining high efficiency.

Embodiment mode 2

Fig. 6 shows the shape of the inner surface of the heat transfer tube 20 according to embodiment 2 of the present invention, and the structure of the heat exchanger 1 is the same as that of embodiment 1. Note that portions that exhibit the same or equivalent functions as those in embodiment 1 are denoted by the same reference numerals (the same applies to the following embodiments). In the present embodiment, the difference H between the groove portion 21 and the ridge portion 22 after the pipe expansion will be described.

Fig. 7 shows a relationship between a difference between the groove 21 and the crest 22 after the expansion (the peak 22a after the expansion) and a heat exchange rate, and in the heat transfer pipe 20, the larger the difference H between the groove 21 and the crest 22 after the expansion, the larger the surface area in the pipe, and the like, the higher the heat transfer coefficient. However, when the difference H between the groove portion 21 and the ridge portion 22 becomes larger than 0.26mm, the increase in pressure loss is larger than the increase in thermal conductivity, and the heat exchange rate is lowered. On the other hand, when the difference H between the groove 21 and the ridge 22 is less than 0.1mm, the thermal conductivity is not improved. Therefore, the heat transfer pipe 20 has a peak 22a and a low peak 22b formed so that the difference H between the groove 21 and the crest 22 after expansion is 0.1mm to 0.26 mm.

According to the heat exchanger 1 of embodiment 2 described above, the high peak 22a and the low peak 22b are formed so that the difference H between the groove portion 21 and the crest 22 after expansion is 0.1mm to 0.26mm, and therefore the heat transfer performance of the heat transfer tube 20 can be improved.

Embodiment 3

Fig. 8 shows the shape of the inner surface of the heat transfer tube 20 according to embodiment 3 of the present invention, and the angle (lead angle or twist angle) γ between the straight line parallel to the tube axial direction of the inner surface of the heat transfer tube 20 and the direction in which the groove portions (spiral grooves) 21 (crest portions 22) extend is 10 degrees to 50 degrees.

Fig. 9 shows the relationship between the lead angle γ of the groove portion (spiral groove) 21 of the heat transfer pipe 20 and the heat exchange rate, and basically, the lead angle γ of the groove portion (spiral groove) 21 of the heat transfer pipe 20 is set in the range of 10 degrees to 50 degrees because, when the lower limit of the lead angle γ of the groove portion (spiral groove) 21 is 10 degrees or less, the reduction in the heat exchange rate becomes remarkable, and further, when the upper limit of the lead angle γ of the groove portion (spiral groove) 21 is 50 degrees or more, the pressure loss in the pipe increases. This makes it difficult to generate a fluid flowing over the groove (spiral groove) 21, and thus a high-efficiency air conditioner can be obtained by improving the heat exchange rate without increasing the pressure loss in the pipe.

As described above, according to the heat exchanger 1 of embodiment 3, the lead angle γ of the groove portion (spiral groove) 21 of the heat transfer pipe 20 is formed to have a peak at 10 degrees to 50 degrees, and therefore, the heat transfer performance of the heat transfer pipe 20 can be improved.

Embodiment 4

Fig. 10 shows the shape of the tube inner surface of the heat transfer tube 20 according to embodiment 4 of the present invention, and in the heat exchanger 1, the apex angle α of the high peak 22a of the heat transfer tube 20 is 15 degrees to 30 degrees, and the apex angle β of the low peak 22b is 5 degrees to 15 degrees.

Basically, the smaller the apex angle at the peak, the larger the heat transfer area of the entire heat transfer pipe 20, and therefore the heat transfer rate increases. However, as shown in fig. 11, when the apex angle α of the peak 22a is smaller than 15 degrees, workability in manufacturing the heat exchanger 1 is significantly reduced, and thus the heat exchange rate is finally reduced. On the other hand, when the apex angle α is larger than 30 degrees, the cross-sectional area of the groove portion 21 becomes smaller, the liquid film of the refrigerant overflows from the groove portion 21, and the liquid film covers the peak portion, so that the thermal conductivity is lowered.

On the other hand, when the apex angle β of the low peak 22b is set to 5 to 15 degrees, the width of the bottom of the peak is also made narrow, and the entire width is made narrow, whereby the heat transfer area becomes large, and the heat conductivity in the tube increases.

As described above, according to the heat transfer tube 20 of embodiment 4, the peak 22a and the low peak 22b are formed such that the vertex angle α of the peak 22a is 15 degrees to 30 degrees and the vertex angle β of the low peak 22b is 5 degrees to 15 degrees, whereby the heat transfer performance of the heat transfer tube 20 can be improved.

Embodiment 5

Fig. 12 shows an air conditioning apparatus as a refrigeration cycle apparatus according to embodiment 5 of the present invention, which includes a heat source side unit (outdoor unit) 100 and a load side unit (indoor unit) 200 that are connected by refrigerant pipes to form a refrigerant circuit and circulate a refrigerant. Among the refrigerant pipes, a pipe through which a gaseous refrigerant (gas refrigerant) flows is a gas pipe 300, and a pipe through which a liquid refrigerant (liquid refrigerant, in some cases, a gas-liquid two-phase refrigerant) flows is a liquid pipe 400. Here, as the refrigerant, for example, a HC single refrigerant or a mixed refrigerant containing an HC refrigerant, R32, R410A, R407C, a non-azeotropic mixed refrigerant composed of tetrafluoropropene (for example, 2, 3, 3, 3-tetrafluoropropene) and an HFC-based refrigerant having a lower boiling point than that of the tetrafluoropropene, carbon dioxide, or the like can be used.

In the present embodiment, the heat-source-side unit 100 is configured by each device (means) of a compressor 101, an oil separator 102, a four-way valve 103, a heat-source-side heat exchanger 104, a heat-source-side fan 105, an accumulator 106, a heat-source-side expansion device (expansion valve) 107, an inter-refrigerant heat exchanger 108, a bypass expansion device 109, and a heat-source-side control device 110.

The compressor 101 has a motor, sucks a refrigerant, compresses the refrigerant, turns into a high-temperature and high-pressure gas state, and flows into a refrigerant pipe. For example, the operation control of the compressor 101 includes a master-side inverter circuit, a slave-side inverter circuit, and the like in the compressor 101, and the capacity (amount of refrigerant to be delivered per unit time) of the compressor 101 can be accurately changed by arbitrarily changing the operating frequency.

The oil separator 102 is used to separate lubricating oil mixed with the refrigerant and discharged from the compressor 101. The separated lubricating oil is returned to the compressor 101. The four-way valve 103 switches the flow of the refrigerant between the cooling operation and the heating operation based on an instruction from the heat source side control device 110. The heat source side heat exchanger 104 is configured using the heat exchanger 1 described in embodiments 1 to 4, and performs heat exchange between the refrigerant and air (outdoor air). For example, during the heating operation, the heat exchanger functions as an evaporator, and performs heat exchange between the low-pressure refrigerant flowing in through the heat-source-side expansion device 107 and air to evaporate and gasify the refrigerant. Further, in the cooling operation, the refrigerant functions as a condenser, and performs heat exchange between the refrigerant compressed in the compressor 101 and the air flowing from the four-way valve 103 side, thereby condensing and liquefying the refrigerant. The heat source-side heat exchanger 104 is provided with a heat source-side fan 105 for efficiently exchanging heat between the refrigerant and the air. The heat source-side fan 105 may have an inverter circuit (not shown) to change the operating frequency of the fan motor arbitrarily and accurately change the rotational speed of the fan.

The heat exchanger 108 related to refrigerant exchanges heat between the refrigerant flowing through the main flow path of the refrigerant circuit and the refrigerant branched from the flow path and having its flow rate adjusted by the bypass expansion device 109 (expansion valve). In particular, when the refrigerant needs to be supercooled during the cooling operation, the refrigerant is supercooled and supplied to the load side unit 200. The heat exchanger related to refrigerant 108 is also configured using the heat exchanger 1 described in embodiments 1 to 4.

The liquid flowing through the bypass throttle device 109 is returned to the accumulator (liquid separator) 106 through a bypass pipe. The accumulator 106 is a mechanism for storing surplus refrigerant of the liquid, for example. The heat source side controller 110 is configured by, for example, a microcomputer or the like, and can perform wired or wireless communication with the load side controller 204, and for example, controls each unit of the air conditioner such as the operation frequency control of the compressor 101 by inverter circuit control based on data detected by various detection units (sensors) in the air conditioner, thereby performing operation control of the entire air conditioner.

On the other hand, the load side unit 200 is composed of a load side heat exchanger 201, a load side expansion device (expansion valve) 202, a load side fan 203, and a load side control device 204. The load-side heat exchanger 201 is also configured using the heat exchanger 1 described in embodiments 1 to 4, and performs heat exchange between the refrigerant and the air in the space to be air-conditioned. For example, during the heating operation, the refrigerant functions as a condenser, and performs heat exchange between the refrigerant flowing from the gas pipe 300 and air, condenses and liquefies (or forms a gas-liquid two-phase) the refrigerant, and flows out to the liquid pipe 400 side. On the other hand, during the cooling operation, the refrigerant functions as an evaporator, and performs heat exchange between the refrigerant in a low-pressure state by the load-side expansion device 202 and air, and the refrigerant takes heat of the air, evaporates, vaporizes, and flows out to the gas pipe 300 side. In addition, the load side unit 200 is provided with a load side fan 203 for adjusting the flow of air for heat exchange. The operating speed of the load side fan 203 is determined by, for example, user settings. The load-side expansion device 202 adjusts the pressure of the refrigerant in the load-side heat exchanger 201 by changing the opening degree.

The load-side controller 204 is also configured by a microcomputer or the like, and can perform wired or wireless communication with the heat-source-side controller 110, for example. Each device (means) of the load side unit 200 is controlled so that the indoor temperature becomes a predetermined temperature, for example, based on an instruction from the heat source side control device 110 or an instruction from an occupant or the like. In addition, a signal including data detected by a detection mechanism provided in the load side unit 200 is transmitted.

Hereinafter, the operation of the air conditioner will be described. First, a basic refrigerant cycle in the refrigerant circuit during the cooling operation will be described. By the driving operation of the compressor 101, the refrigerant of the high-temperature and high-pressure gas (gaseous state) discharged from the compressor 101 passes through the four-way valve 103, passes through the heat source side heat exchanger 104, is condensed, turns into a liquid refrigerant, and flows out to the heat source side unit 100. The refrigerant flowing into the load side unit 200 through the liquid pipe 400 is turned into a low-temperature low-pressure liquid refrigerant whose pressure has been adjusted by adjusting the opening degree of the load side expansion device 202, passes through the load side heat exchanger 201, evaporates, and flows out. Then, the gas flows into the heat source side unit 100 through the gas pipe 300, is sucked into the compressor 101 through the four-way valve 103 and the accumulator 106, is pressurized again, and is discharged, thereby circulating.

A basic refrigerant cycle in the refrigerant circuit during heating operation will be described. By the driving operation of the compressor 101, the refrigerant of the high-temperature and high-pressure gas (gaseous state) discharged from the compressor 101 flows from the four-way valve 103 into the load side unit 200 through the gas pipe 300. In the load side unit 200, the pressure is adjusted by the opening degree adjustment of the load side expansion device 202, and the refrigerant passes through the load side heat exchanger 201, is condensed, becomes a liquid at an intermediate pressure or a gas-liquid two-phase refrigerant, and flows out of the load side unit 200. The refrigerant flowing into the heat source side unit 100 through the liquid pipe 400 is adjusted in pressure by adjusting the opening degree of the heat source side expansion device 107, passes through the heat source side heat exchanger 104, is evaporated into a gas refrigerant, is sucked into the compressor 101 through the four-way valve 103 and the accumulator 106, is pressurized and discharged as described above, and circulates.

As described above, according to the air conditioning apparatus of embodiment 5, the heat exchangers 1 of embodiments 1 to 4 having high heat exchange rates are used as the evaporator and the condenser in the heat source side heat exchanger 104 of the heat source side unit 100, the heat exchanger 108 related to the refrigerant, and the load side heat exchanger 201 of the load side unit 200, and therefore COP (Coefficient of Performance) and the like can be improved, and energy saving and the like can be achieved.

In embodiment 5 described above, the heat exchanger according to the present invention is used in an air conditioning apparatus, but the present invention is not limited to these apparatuses, and can be used in other refrigeration cycle apparatuses such as a refrigeration apparatus and a heat pump apparatus that constitute a refrigerant circuit and include a heat exchanger serving as an evaporator and a condenser.

Examples

Hereinafter, examples of the present invention will be described in comparison with comparative examples outside the scope of the present invention. As shown in table 1, heat exchangers 1 (example 1 and example 2) having an outer diameter of 7mm, a bottom wall thickness of the groove 21 of 0.25mm, a lead angle of 30 degrees, and the number of peaks 22a of 11 and 19 were produced. Further, as comparative examples, heat exchangers having an outer diameter of 7mm, a bottom wall thickness of the groove of 0.25mm, and the number of peaks of 6 and 30 were produced (comparative examples 1 and 2).

[ Table 1]

	Outer diameter (mm)	Wall thickness of the bottom (mm)	Lead angle (degree)	Number of strips (Peak) ()	Heat exchange Rate (%)
						Comparative example 1	7	0.25	30 degree	6	99
Example 1	7	0.25	30 degree	11	101.3
						Example 2	7	0.25	30 degree	19	101
Comparative example 2	7	0.25	30 degree	30	99.5

As is clear from table 1, the heat exchange rates of the heat exchangers 1 of example 1 and example 2 were 101.3% and 101%, the heat exchange rates of the heat exchangers of comparative example 1 and comparative example 2 were 99% and 99.5%, and the heat exchangers 1 of example 1 and example 2 were high in both heat exchange rates and improved in-pipe heat transfer performance as compared with the heat exchangers of comparative example 1 and comparative example 2.

Next, as shown in table 2, heat exchangers 1 (examples 3, 4, and 5) were produced in which the outer diameter was 7mm, the bottom wall thickness of the groove 21 was 0.25mm, the lead angle was 30 degrees, and the ratio W1/D of the tip width W1 of the peak 22a to the outer diameter D of the heat transfer tube 20 was 0.011, 0.020, and 0.040. Further, as comparative examples, heat exchangers were produced in which the outer diameter was 7mm, the bottom wall thickness of the grooves was 0.25mm, the lead angle was 30 degrees, and the ratio W1/D between the tip width of the peak and the outer diameter of the heat transfer tube was 0.005 and 0.050 (comparative examples 3 and 4).

[ Table 2]

As is clear from table 2, the heat exchange rates of the heat exchangers 1 of examples 3, 4 and 5 were 101.2%, 101.8% and 101%, the heat exchange rates of the heat exchangers of comparative examples 3 and 4 were 99.2% and 98%, and the heat exchangers 1 of examples 3, 4 and 5 were high in all of the heat exchange rates and improved in-tube heat transfer performance as compared with the heat exchangers of comparative examples 3 and 4.

Next, as shown in table 3, heat exchangers 1 (example 6 and example 7) having an outer diameter of 7mm, a bottom wall thickness of the groove 21 of 0.25mm, a lead angle of 30 degrees, and groove depths after pipe expansion of 0.1mm and 0.26mm were produced. Further, as comparative examples, heat exchangers having an outer diameter of 7mm, a groove bottom wall thickness of 0.25mm, a lead angle of 30 degrees, a groove depth after pipe expansion of 0.05mm, and a groove depth after pipe expansion of 0.3mm were produced (comparative examples 5 and 6).

[ Table 3]

As is clear from table 3, the heat exchange rates of the heat exchangers 1 of examples 6 and 7 were 101.5% and 101.2%, the heat exchange rates of the heat exchangers of comparative examples 5 and 6 were 99% and 99.4%, and the heat exchangers 1 of examples 6 and 7 were high in both heat exchange rates and improved in-tube heat transfer performance as compared with the heat exchangers of comparative examples 5 and 6.

Next, as shown in table 4, heat exchangers 1 (example 8, example 9, and example 10) having an outer diameter of 7mm, a bottom wall thickness of the groove 21 of 0.25mm, a vertex angle of 30 degrees, and lead angles γ of 10 degrees, 30 degrees, and 50 degrees were produced. Further, as comparative examples, heat exchangers having an outer diameter of 7mm, a bottom wall thickness of the groove of 0.25mm, a vertex angle of 30 degrees, and lead angles of 5 degrees and 60 degrees were produced (comparative examples 7 and 8).

[ Table 4]

	Outer diameter (mm)	Wall thickness of the bottom (mm)	Top angle (degree)	Lead angle (degree)	Heat exchange Rate (%)
						Comparative example 7	7	0.25	30 degree	5	99.2
Example 8	7	0.25	30 degree	10	100.9
						Example 9	7	0.25	30 degree	30	101.5
Example 10	7	0.25	30 degree	50	100.8
						Comparative example 8	7	0.25	30 degree	60	99.5

As is clear from table 4, the heat exchange rates of the heat exchangers 1 of examples 8, 9 and 10 were 100.9%, 101.5% and 101.8%, the heat exchange rates of the heat exchangers of comparative examples 7 and 8 were 99.2% and 99.5%, and the heat exchangers 1 of examples 8, 9 and 10 were high in the heat exchange rate and improved in the tube heat transfer performance as compared with the heat exchangers of comparative examples 7 and 8.

Next, as shown in table 5, heat exchangers 1 (examples 11 and 12) having an outer diameter of 7mm, a bottom wall thickness of the groove 21 of 0.25mm, a lead angle of 30 degrees, and a vertex angle α of 15 degrees and 30 degrees were produced. Further, as comparative examples, heat exchangers having an outer diameter of 7mm, a bottom wall thickness of 0.25mm, a lead angle of 30 degrees, and vertex angles of 10 degrees and 40 degrees were produced (comparative examples 9 and 10).

[ Table 5]

	Outer diameter (mm)	Wall thickness of the bottom (mm)	Lead angle (degree)	Top angle (degree)	Heat exchange Rate (%)
						Comparative example 9	7	0.25	30 degree	10	99
Example 11	7	0.25	30 degree	15	101
						Example 12	7	0.25	30 degree	30	101.3
Comparative example 10	7	0.25	30 degree	40	99.3

As is clear from table 5, the heat exchange rates of the heat exchangers 1 of examples 11 and 12 were 101% and 101.3%, the heat exchange rates of the heat exchangers of comparative examples 9 and 10 were 99% and 99.3%, and the heat exchangers 1 of examples 11 and 12 were high in both heat exchange rates and improved in-tube heat transfer performance as compared with the heat exchangers of comparative examples 9 and 10.

Description of reference numerals

1 heat exchanger, 10 fins, 11 through-holes, 20 heat transfer tubes, 21 grooves, 22 crests, 22a crests, 22b troughs, 30 expansion balls, 31 rods, 100 heat source side units, 101 compressor, 102 oil separator, 103 four-way valve, 104 heat source side heat exchanger, 105 heat source side fan, 106 accumulator, 107 heat source side throttling device, 108 inter-refrigerant heat exchanger, 109 bypass throttling device, 110 heat source side control device, 200 load side unit, 201 load side heat exchanger, 202 load side throttling device, 203 load side fan, 204 load side control device, 300 gas piping, 400 liquid piping, apex angle of α crest, apex angle of β crest, direction (lead angle) in which crest extends with respect to tube axis direction, outer diameter of heat transfer tubes of D, height of crest after H expansion, curvature radius of crest of R1 crest, w1 expands the width of the top of the peak top part of the post-expansion peak.

Claims (11)

1. A heat transfer tube for a heat exchanger, characterized in that,

a peak and a low peak lower than the peak are spirally arranged at a predetermined height in the tube axis direction of the inner surface of the tube,

11 to 19 peaks are formed at the high peaks, 3 to 6 peaks are formed at the low peaks between the high peaks,

the peak is in a trapezoidal section with a plane peak top part before pipe expansion, and the ratio of the top end width of the peak top part after pipe expansion to the outer diameter of the heat transfer pipe is 0.011-0.040.

2. The heat transfer tube for a heat exchanger according to claim 1, wherein the peak height before expansion is 0.04mm or more higher than the peak height.

3. The heat transfer tube for a heat exchanger according to claim 1 or 2, wherein the plane of the peak top of the peak before expansion and the respective radii of curvature of both side surfaces are 0.01mm to 0.03 mm.

4. The heat transfer tube for a heat exchanger according to any one of claims 1 to 3, wherein the apex angle of the high peak before tube expansion is 15 degrees to 30 degrees, and the apex angle of the low peak is 5 degrees to 15 degrees.

5. The heat transfer tube for a heat exchanger according to any one of claims 1 to 4, wherein the curvature radius of the crest of the low peak is 0.03mm to 0.045 mm.

6. The heat transfer pipe for a heat exchanger according to any one of claims 1 to 5, wherein a direction in which the crest extends is 10 degrees to 50 degrees with respect to a pipe axial direction.

7. A heat exchanger, comprising: a plurality of fins for performing heat exchange; the heat transfer tube according to any one of claims 1 to 6 penetrating the fin,

the heat transfer tube is expanded by pressurizing the heat transfer tube from the inner surface side, and the heat transfer tube is joined to the fin.

8. The heat exchanger of claim 7, wherein the height of the peaks after tube expansion is 0.10mm to 0.26 mm.

9. A refrigeration cycle apparatus in which a refrigerant circuit for circulating a refrigerant is configured by connecting a compressor for compressing the refrigerant, a condenser for condensing the refrigerant by heat exchange, an expansion mechanism for decompressing the condensed refrigerant, and an evaporator for evaporating the decompressed refrigerant by heat exchange via pipes,

the heat exchanger according to claim 7 or 8 is provided in both or either one of the condenser and the evaporator.

10. A refrigeration cycle apparatus according to claim 9, wherein any one of a HC single refrigerant or a mixed refrigerant containing HC, R32, R410A, R407C, a non-azeotropic mixed refrigerant of tetrafluoropropene and an HFC-based refrigerant having a lower boiling point than that of tetrafluoropropene, or carbon dioxide is used as the refrigerant.

11. An air conditioning apparatus, characterized in that cooling and heating of a target space are performed by the refrigeration cycle apparatus according to claim 9 or 10.