Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
  • F28F1/00—Tubular elements; Assemblies of tubular elements
  • F28F1/10—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses
  • F28F1/40—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses the means being only inside the tubular element

Definitions

• the present invention relates to a heat exchanger and a heat exchanging apparatus that are used for a cooling apparatus such as an air conditioning apparatus, a refrigerator and a freezer.
• a heat exchanging apparatus such as an air conditioner, a refrigerator and a freezer generally comprises a heat exchanger for condensation, a heat exchanger for evaporation, a pump that sends heat transfer gas from a downstream end of the heat exchanger for evaporation to an upstream end of the heat exchanger for condensation, and a capillary tube portion that controls flow of heat transfer liquid flowing from a downstream end of the heat exchanger for condensation to an upstream end of the heat exchanger for evaporation.
• Air-cooling or heating is performed by means that the heat exchanger for condensation liquidizes heat transfer gas to emit condensed heat while the heat exchanger for evaporation evaporates heat transfer liquid to take away the heat of evaporation.
• the present inventors researched the behavior of the heat transfer medium in the heat exchanger in detail, and as result, found out the following facts as a result.
• the present invention was made based on the above new findings.
• the object of the present invention is to provide a heat exchanger and a heat exchanging apparatus that is capable of improving the heat exchanging efficiency by reducing the loss of pressure while maintaining the heat conductivity of the heat transfer tube.
• the heat exchanger of the present invention comprises a number of planar fins parallelly arranged with spaces therebetween and a heat transfer tube that is fixed on these fins and forms a meandering form as an entire body, capable of flowing heat transfer medium from upstream to downstream of the heat transfer tube, and it is characterized in that the downstream portion having 10 to 30% of the entire length of the heat transfer tube includes an inner surface structure with a smaller loss of pressure at the time of passage of the heat transfer medium in comparison with that of the remaining upstream portion.
• a second heat exchanger comprises a number of planar fins parallelly arranged with spaces therebetween and a heat transfer tube that is fixed on these fins and forms a meandering form as an entire body, and it is characterized in that both end portions, each having 10 to 30% of the entire length of the heat transfer tube, include inner surface structures with a smaller loss of pressure at the time of passage of the heat transfer medium in comparison with that of the remaining central portion.
• a first heat exchanging apparatus comprises a heat exchanger for condensation, a heat exchanger for evaporation, a pump sending a heat transfer medium gas from a downstream end of the heat exchanger for evaporation to an upstream end of the heat exchanger for condensation, and a fluid resistance portion controlling a flow of the heat transfer medium liquid that flows from the downstream end of the heat exchanger for condensation to the upstream end of the heat exchanger for evaporation, and is characterized in that the heat exchanger for condensation and the heat exchanger for evaporation includes a number of planar fins parallelly arranged with spaces therebetween and a heat transfer tube that is fixed on these fins and forms a meandering form as an entire body, and further, at least in one of the heat exchanger for condensation and the heat exchanger for evaporation, the downstream portion having 10 to 30% of the entire length of the heat transfer tube includes an inner surface structure with a smaller loss of pressure at the time of passage of the heat transfer medium in comparison with that of the remaining upstream portion.
• a second heat exchanging apparatus comprises a first and a second heat exchangers, a pump sending the heat transfer medium from either one of the first and a second heat exchangers to the other one, a fluid resistance portion controlling a flow of the heat transfer medium that flows back from the other one of the first and second heat exchangers to the one, and a reversing mechanism reversing a flow of the heat transfer medium, and it is characterized in that the heat exchanger for condensation and the heat exchanger for evaporation includes a number of planar fins parallelly arranged with spaces therebetween and a heat transfer tube that is fixed on these fins and forms a meandering form as an entire body, and further, at least at either one of the heat exchanger for condensation and the heat exchanger for evaporation, the both end portions, each having 10 to 30% of the entire length of the heat transfer tube, include inner surface structures with a smaller loss of pressure at the time of passage of the heat transfer medium in comparison with that of the remaining central portion.
• the inner tube surface structure such as the fins or the grooves with a smaller loss of pressure at the time of passage of the heat transfer medium in comparison with that of the remaining portion of the heat transfer tube is provided on the inner surface of the heat transfer tube that are located in the area where most part of the heat transfer medium flowing in the heat transfer tube liquidizes or the area where most part of the heat transfer medium evaporates. Therefore, the loss of pressure of the heat transfer medium flowing in the heat exchanger can be minimized while maintaining an improving effect of the heat, and high heat exchanging efficiency can be obtained as a result.
• FIG. 1 is a schematic view showing one embodiment of the heat exchanging apparatus according to the present invention.
• FIG. 2 is a sectional view showing one embodiment of the heat exchanger that can be used in the heat exchanging apparatus.
• FIG. 3 is a cross sectional view showing another embodiment of the heat exchanger.
• FIG. 4 is a cross sectional view showing another embodiment of the heat exchanger.
• FIG. 5 is a cross sectional view of a principal portion showing another embodiment of the heat exchanger.
• FIG. 6 is a transverse cross sectional view of one example of the heat transfer tube that is used in the heat exchanger.
• FIG. 7 is a partially expanded plan view of the inner surface of the heat transfer tube.
• FIG. 8 is a cross sectional view showing another embodiment of the heat exchanger.
• FIG. 9 is a cross sectional view showing another embodiment of the heat exchanger.
• FIG. 10 is a cross sectional view showing still another embodiment of the heat exchanger.
• FIG. 11 is a schematic view showing another embodiment of the heat exchanging apparatus according to the present invention.
• FIG. 12 is a cross sectional view showing one embodiment of the heat exchanger that can be used in the heat exchanging apparatus.
• FIG. 1 is a sectional view showing one embodiment of a heat exchanging apparatus according to the present invention.
• This heat exchanging apparatus comprises a heat exchanger for condensation 1 , a heat exchanger for evaporation 2, a pump 4 that sends heat transfer gas from a downstream end 2B of the heat exchanger for evaporation 2 to an upstream end 1A of the heat exchanger for condensation 1, and a fluid resistance portion 6 controlling a flow of the heat transfer medium liquid that flows from the downstream end IB of the heat exchanger for condensation 1 to the upstream end 2 A of the heat exchanger for evaporation 2.
• Air-cooling or heating is performed by means that the heat exchanger for condensation 1 liquidizes heat transfer gas to emit condensed heat while the heat exchanger for evaporation 2 evaporates heat transfer liquid to deprive the heat of vaporization.
• a fluid resistance portion 6 a capillary tube or other flow adjusting valves, which have conventionally been used, can be used.
• FIG. 2 shows a first embodiment of the heat exchanger for condensation 1 and/or the heat exchanger for evaporation 2.
• the fundamental structures of the heat exchanger for condensation 1 and the heat exchanger for evaporation 2 are the same to each other, and the both heat exchangers are mainly constituted of a number of planar fins (heat sinks, or radiator fins) 14 parallelly arranged with spaces therebetween and a heat transfer tube 8 that is fixed on these planar fins 14 and forms a meandering form as an entire body.
• the heat transfer medium is made to flow from the upstream end (upper end of FIG. 2 in this example) to the downstream end (lower end of FIG. 2) of the heat transfer tube 8.
• the kind of the heat transfer medium is not limited in the present invention, but may be any kind such as a fluorine compound (such as fluorocarbon), carbon dioxide, water and alcohol that have conventionally been used.
• the heat transfer tube 8 is generally made of a metal with high heat conductivity such as copper, copper alloy, aluminum and aluminum alloy, and it comprises a number of straight tube portions 8A and 8B that perpendicularly penetrate and are fixed on the planar fins 14 made of a metal with high heat conductivity similar to the heat transfer tube 8, and bent tube portions 10 A, 10B, 12A and 12B connecting end portions of adjacent straight tube portions 8A and 8B, which constitute one tube as an entire body.
• a long u-shaped tube consisting of two straight tube portions 8A (8B) and a bent tube portion 10A (10B) is inserted into holes of the planar fins 14, and then the straight tube portions 8 A (8B) are subjected to tube enlargement process to fix the planar fins 14.
• short u-shaped tubes that are the bent tube portions 12A (12B) are fitted on the both ends of the long u-shaped tubes, and are fixed by brazing, welding or the like. With this method, the planar fins 14 are fixed substantially on entire length of the straight tube portions 8 A and 8B.
• the heat exchanger of the present invention is not limited to such assembling method, but other assembling method may be adopted.
• the heat exchanging apparatus is characterized in that, at least in either one of the heat exchanger for condensation 1 and the heat exchanger for evaporation 2, a downstream portion L or G having 10 to 30% of the entire length of the heat transfer tube 8 includes a inner tube surface structure with smaller loss of pressure at the time of passage of the heat transfer medium in comparison with that of the remaining upstream portion GL.
• the present invention is applied to only one of the heat exchanger for condensation 1 and the heat exchanger for evaporation 2
• the other one may be a regular heat exchanger.
• the heat exchanger according to the present invention is characterized in that the downstream portion L or G having 10 to 30% of the entire length of the heat transfer tube 8 includes a inner tube surface structure with smaller loss of pressure at the time of passage of the heat transfer medium in comparison with that of the remaining upstream portion GL.
• the downstream portion L of the heat exchanger for condensation 1 liquidizes, therefore, the downstream portion L becomes a single phase flow area where substantially only liquid flows.
• the downstream portion G of the heat exchanger for evaporation 2 since the most part of the heat transfer medium evaporate in the downstream portion G of the heat exchanger for evaporation 2, the downstream portion G becomes a single-phase flow area where substantially only gas flows. In these single-phase flow areas, the heat conductivity improving effect by the fins deteriorate in comparison with the double-phase flow area GL where gas and liquid heat transfer mediums coexist.
• the downstream portion L or G cannot cover the single-phase flow area sufficiently, resulting that there is a fear that the loss of pressure will be increased.
• the length of the downstream portion L or G is more than 30% of the entire length of the heat transfer tube 8, the heat conductivity improving effect by the fins 24 becomes insufficient, resulting that there is a fear that the entire heat exchange capability will deteriorate. More preferably, the length of the downstream portion L or G is made to be 15 to 20% of the entire length of the heat transfer tube 8.
• the fins 24 that are arranged in a form of zigzag to the circumference direction of the inner surface of the tube are formed as shown in FIG. 6 and FIG. 7, on the other hand, on the inner surface of the straight tube portions 8B that are located in the downstream area L (G) of the heat transfer tube 8, linear fins 28 that are parallel to the tube axis are formed. Note that the fins 24 and 28 are formed across entire length of the straight tube areas 8 A and 8B, but the fins 24 and 28 may be formed only partially on the inner surface of the straight tube portions 8 A and 8B as occasion demands.
• w-shaped fins On the inner circumference surface of the straight tube portions 8 A, w-shaped fins
• the straight tube portion 8A is manufactured by an electro resistance welded tube process, one weld line 20 extending to the tube axis direction is formed on the inner circumference surface across the entire length, and the fins 24 are divided with the weld line 20 as a boundary.
• the weld line 20 is preferably a protruded line having a smaller protruded amount than that of the fins 24.
• planar portions 22 of a specified width are formed for stabilizing welding.
• the fins 24 are parallelly arranged in the same area Rl to R4, but they may not necessarily be parallel and inclined angle may be different for each fin. Moreover, widths of the areas Rl to R4 also may be not equal to each other. The lead angles of the fins may be different for respective area Rl to R4. The bent portions of the fins 24 may be in a form of a gentle curve, or a cut (groove) may be made at the boundary among the areas Rl to R4 to reduce the loss of pressure.
• the lead angle ⁇ of the fin 24 to the tube axis is not limited, but it is generally preferable to be 5 to 25 degrees, more preferably 10 to 20 degrees. If the lead angle exceeds
• the loss of pressure becomes larger, which is not preferable. Moreover, if the lead angle is less than 5 degrees, the turbulent effect for the heat transfer medium by the fins 24 deteriorate.
• the sectional shape of the fin 24 may be any shape such as a triangular shape, an isosceles triangular shape, a triangular shape with its vertex roundly chamfered off, a half circular shape, a circular arc shape, a trapezoid shape, and a chamfered trapezoid shape.
• an isosceles triangular shape with its vertex chamfered off is taken as shown in FIG. 6.
• a pitch of the fin 24 is approximately 0.25 to 0.5 mm, a height of the fin 24 is approximately 0.1 to 0.3 mm, an angle made by the both sides of the fin 24 is approximately 5 to 50 degrees.
• the fin pitch is approximately 0.3 to 0.4 mm, the fin height is approximately 0.15 to 0.25 mm, and the angle made by the both sides of the fin 24 is approximately 20 to 25 degrees.
• the linear fins 28 that are formed on the inner circumference surface of the straight tube portion 8B may be the same as to the height, the sectional shape, pitch and the like as the fin 24 of the straight tube portion 8 A except the lead angle is substantially 0 degree.
• the fins are the same, the tube enlargement characteristic of the straight tube portion 8B and the tube enlargement characteristic of the straight tube portion 8 A becomes substantially identical, thus fixing work of the heat transfer tube to the planar fins 14 will be facilitated.
• the fins may be or may not be formed on the inner surface of the bent tube portions 10A, 10B, 12A and 12B. It is because the flow of the heat transfer medium in the bent tube portions 10 A, 10B, 12A and 12B makes an acute turn and the heat transfer medium flow is sufficiently agitated without the fins, thus the effect of fins is not significant. From a viewpoint of reducing the loss of pressure, the inner surface of the bent tube portions 10A, 10B, 12A and 12B may preferably be a smooth surface without the fins. However, since the bent tube portions 10A and 10B are generally formed by the same metal tube as the straight tube portions 8A and 8B, forming no fins only in the bent portions 10A and 10B will cause an increase of cost.
• the same fins as the ones in the straight tube portions 8A and 8B may be formed in the bent tube portions 10A and 10B. Because the bent tube portions 12A and 12B are constituted of the different members, it is easy to make the entire inner surface a smooth planar state.
• one or a plurality of protruded lines 18 for sound reduction may be formed in parallel to the tube axis.
• protruded lines 18 for sound reduction are formed, an effect of settling a vigorous turbulent flow in the bent tube portion is obtained, not only noise generation can be reduced but also an effect of settling the heat transfer flow that flows into the straight tube portions 8A and 8B is obtained.
• the linear fins 28 with smaller loss of pressure at the time of passage of the heat transfer medium in comparison with that of the remaining double-phase slow portion GL of the heat transfer tube 8 are formed on the inner surface of the heat transfer tube 8, which is located in the single-phase flow area L where most part of the heat transfer medium flowing in the heat transfer tube 8 liquidizes or in the single-phase flow area G where most part of the heat transfer medium evaporates. Therefore, the loss of pressure of the heat transfer medium flowing in the heat exchanger 1 (2) can be minimized while maintaining an improving effect of the heat conductivity by the zigzag-shaped fins 24 formed in the double-phase flow area GL.
• FIG. 3 shows a second embodiment of the heat exchanger 1 for condensation and/or the heat exchanger 2 for evaporation.
• the fins 24 are arranged in a form of zigzag similar to the first embodiment.
• spiral fins 30 having a specified lead angle against the tube axis are formed. The similar effect as the first embodiment can be obtained with such a heat exchanger. Other constitutions may be the same as that of the first embodiment.
• the lead angle of the fin 30 is not limited, it is preferably 10 degrees or less. If the lead angle is to large, the loss of pressure at the downstream portion L or G increases, thus the effect of the present invention cannot be obtained.
• Other parameters of the fin 30 may be the same as the above-described fin 24. When the parameters are the same, the tube enlargement characteristic of the straight tube portion 8C and the tube enlargement characteristic of the straight tube portion 8 A becomes substantially identical, thus there is advantage that fixing work of the heat transfer tube to the planar fins 14 will be facilitated.
• FIG. 4 shows a third embodiment of the heat exchanger 1 for condensation and/or the heat exchanger 2 for evaporation.
• the fins 24 are arranged in a form of zigzag similar to the first embodiment.
• the inner surface of the straight tube portions 8D that are located in the downstream portion L (G) of the heat transfer tube 8 is made to be a smooth surface with no fins formed. The similar effect as the first embodiment can be obtained with such a heat exchanger. Other constitutions may be the same as that of the first embodiment.
• FIG. 8 shows a fourth embodiment of the heat exchanger 1 for condensation and/or the heat exchanger 2 for evaporation.
• spiral fins 32 having a first lead angle against the tube axis are formed.
• the linear fins 28 that are parallel to the tube axis are formed. The similar effect as the first embodiment can be obtained with such a heat exchanger.
• the lead angle made by the fin 32 and the tube axis is not limited, from a viewpoint of improving the heat conductivity of the straight tube portion 8E, it is preferably 10 to 30 degrees, and more preferably, 15 to 20 degrees.
• Other parameters of the fin 32 may be the same as the fin 24 of the first embodiment.
• Other constitutions may be the same as that of the first embodiment.
• FIG. 9 shows a fifth embodiment of the heat exchanger 1 for condensation and/or the heat exchanger 2 for evaporation.
• the spiral fins 32 On the inner surface of the straight tube portions 8E that are located in the upstream portion GL of the heat transfer tubes 8, the spiral fins 32 having the first lead angle against the tube axis are formed.
• spiral fins 34 On the inner surface of the straight tube portions 8C that are located in the downstream portion L (G) of the heat transfer tube 8, spiral fins 34 that makes a second lead angle, which is smaller than the first lead angle, against the tube axis are formed.
• the second lead angle made by the fin 34 and the tube axis is not limited, from a viewpoint of reducing the loss of pressure of the straight tube portion 8C, it is preferably 10 degrees or less and more preferably 8 degrees or less.
• Other parameters of the fin 34 may be the same as the fin 24 of the first embodiment.
• Other constitutions may be the same as that of the first embodiment. The similar effect as the first embodiment can be obtained with such a heat exchanger.
• FIG. 10 shows a sixth embodiment of the heat exchanger 1 for condensation and/or the heat exchanger 2 for evaporation.
• the spiral fins 32 having the first lead angle against the tube axis are formed.
• the inner surface of the straight tube portions 8D that are located in the downstream portion L (G) of the heat transfer tube 8 is made to be a smooth surface with no fins formed.
• the similar effect as the first embodiment can be obtained with such a heat exchanger.
• Other constitutions may be the same as that of the first embodiment.
• FIG. 11 shows another embodiment of the heat exchanging apparatus and a seventh embodiment of the heat exchanger according to the present invention.
• This embodiment is the one in which the present invention is applied, for example, to an air conditioner capable of switching heating and air-cooling, for example, and it comprises a first heat exchanger 40, a second heat exchanger 42, a pump that sends the heat transfer medium from one of the first heat exchanger 40 and the second heat exchanger 42 to the other, a fluid resistance portion 6 that controls the flow of the heat transfer medium flowing back from the other one of the first heat exchanger 40 and the second heat exchanger 42 to the one, and a reversing mechanism 44 that reverses the flow of the heat transfer medium.
• a regular capillary tube or the like can be used similarly to the first embodiment.
• a reversing mechanism 44 a switching valve such as a four- way type valve can be used, and other types of reversing mechanism to reverse the action of the pump 4 itself may be provided.
• At least one of the first heat exchanger 40 and the second heat exchanger 42 includes a structure as shown in FIG. 12.
• the heat exchanger 40 (42) comprises a number of planar fins 14 parallelly arranged with spaces therebetween and a heat transfer tube 8 that is fixed on these fins 14 and forms a meandering form as an entire body, and both end portions D of the heat transfer tube 8 respectively having 10 to 30% of the entire length of the heat transfer tube includes an inner surface structure with smaller loss of pressure at the time of passage of the heat transfer medium in comparison with that of the remaining central portion C.
• the fins 24 are arranged in a form of zigzag to the circumference direction of the tube inner surface are formed.
• linear fins 28 that are parallel to the tube axis are formed.
• the fins 24 and 28 may be the same as those of the first embodiment.
• other constitutions also may be the same as those of the first embodiment.
• the shape of fin in the central portion C may be formed in a spiral shape such as the fin 32, or the shape of fin in the both end portions D may be formed in a gentle spiral shape or D may be a smooth surface without the fin.
• the single-phase flow area where most part of the heat transfer medium liquidizes or the single-phase flow area where most part of the heat transfer medium evaporates occurs in either one of the both end portions D in which the linear fins 28 with the smaller loss of pressure are formed. Therefore, the loss of pressure of the heat transfer medium flowing in the heat exchanger can be reduced while maintaining an improving effect of the heat conductivity by the in a form of zigzag fins 24 formed in the central portion C, and high heat exchanging efficiency can be obtained as a result.
• the shape of fin shape in the upstream portion GL or the central portion C may be changed to other inner surface structures having a good heat conductive capability.
• grooves with partially narrowed opening widths may be formed, for example, by crossing two kinds of grooves to form by rolling on the inner surface of the metal tube, or concave portions, dimples, or discontinuous short fins may be arranged in a specified pattern.
• the present invention is not limited to the above-described embodiments, and it is matter of course that the constitution may appropriately be changed if occasion demands without departing from the scope and the spirit of the present invention.
• the inner tube surface structure such as the fins or the grooves with a smaller loss of pressure at the time of passage of the heat transfer medium in comparison with that of the remaining portion of the heat transfer tube is provided on the inner surface of the heat transfer tube that are located in the area where most part of the heat transfer medium flowing in the heat transfer tube liquidizes or the area where most part of the heat transfer medium evaporates. Therefore, the loss of pressure of the heat transfer medium flowing in the heat exchanger can be minimized while maintaining an improving effect of the heat, and high heat exchanging efficiency can be obtained as a result.

Landscapes

• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Geometry (AREA)
• Thermal Sciences (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (1)

Family

ID=17972944

Family Applications (1)

Country Status (3)

Cited By (3)

Families Citing this family (6)

Citations (5)

• 1999
  • 1999-10-28 JP JP30775999A patent/JP2001124480A/ja active Pending
• 2000
  • 2000-10-27 AU AU79600/00A patent/AU7960000A/en not_active Abandoned
  • 2000-10-27 WO PCT/JP2000/007543 patent/WO2001031275A1/en active Application Filing

Patent Citations (5)

Non-Patent Citations (3)

Also Published As

Similar Documents

Legal Events