Patent Grant
7762318
The present application claims priority to Chinese Patent Application No. 200510134632.8, entitled “A Condensing Heat-Exchange Copper Tube for a Flooded Type Electrical Refrigeration Unit”, filed on Dec. 13, 2005.
The present invention relates to a condensing heat-exchange tube, especially to a condensing heat-exchange copper tube for a flooded type electrical refrigeration unit.
In recent years, the development of the manufacturing technology for a refrigerator or an air conditioner has been advanced due to a rapid development in the refrigeration technique and air-conditioning technique. Most effort is concentrated on providing a refrigerator or air conditioner with higher efficiency, less volume and lower weight, as well as an improved refrigerant. Meanwhile, the design and technical application for a heat-exchange tube used in the refrigerator or air conditioner has also been continuously improved. However, current heat-exchange tubes are all problematic in that a condensate film which functions as a thermal resistance develops when the refrigerant tries to condense, which thermal resistance adversely affects the heat transfer thus degrades the refrigeration efficiency. A most commonly used solution is to incorporate fins on the heat-exchange tube or directly form fins on the heat-exchange tube. However, heat resistance develops between the interface of the incorporated fins and the heat-exchange tube, which degrades the heat transfer efficiency of the heat-exchange tube. On other hand, fins directly formed on the heat-exchange tube are usually of small height, and it is difficult to achieve a relatively large heat transfer area on the heat-exchange tube. To increase the heat transfer area, one method is to stamp down a large portion of the fin so as to form a boss extending outwardly from the fin. However, heat transfer area for a heat-exchange tube so developed has not been increased markedly, since the only difference is that a portion of the original lateral surface is converted into a top surface perpendicular to the fin. Meanwhile, the boss is ineffective to attenuate or eliminate the condensate film, neither is it beneficial for a breaking off of the condensate film from the surface of the heat-exchange tube. Therefore, this boss configuration may not substantially improve or enhance the heat transfer property of the condensing heat-exchange tube and the condenser.
An object of the present invention is to provide a heat-exchange tube with higher efficiency.
A technical solution is developed to achieve said object. A condensing heat-exchange copper tube for a flooded type electrical refrigeration unit according to the present invention comprises a smooth surface portion, a finned portion provided with plurality of fins and a transitional portion connecting the smooth surface portion to the finned portion, with a fin base close to the outer surface of the heat-exchange tube and a fin top away from the outer surface provided on a fin. Said fin is further provided with a secondary fin, wherein a certain distance is provided between two axially adjacent secondary fins, and the distance between the secondary fin and the top surface of the fin is between ⅓ and ⅔ of the overall height of the fin.
Preferably, the fin is further provided with a third fin developed by stamping the fin radially downwardly from the top surface of the fin, wherein a certain distance is provided between two axially adjacent third fins.
Preferably, the third fin is arranged above the secondary fin along the same radial line.
Preferably, the third fin and the secondary fin are staggeredly arranged along the axial direction.
Preferably, the cross-section of the third fin defines a right triangle perpendicular to the fin, wherein a third groove is defined between the top surface of the third fin and the fin top, with the depth of the third groove between 0.15 and 0.45 mm, and the width of the third fin between 0.15 and 0.35 mm.
Preferably, the cross-section of the secondary fin defines a right triangle perpendicular to the fin, wherein a distance between the upper surface of the secondary fin and the top surface of the fin is between 0.3 and 0.7 mm, and the width of the secondary fin is between 0.15 and 0.35 mm.
Preferably, the width of the secondary fin is equal to the distance between two neighboring edges of two axially adjacent secondary fins 32.
Preferably, inner teeth are provided on the inner surface of the heat-exchange tube, wherein the inner tooth defines a substantially triangular section, with both the top and the root of the tooth rounded.
Preferably, the height of the inner tooth is between 0.2 and 0.4 mm, the addendum angle thereof is between 30° and 60°, and the pitch angle for the inner tooth is between 30° and 60 °.
Preferably, characterized in that: fins are arranged through a single spiral configuration, with a pitch angle between 0.3° and 1.5°.
The present invention is advantageous over prior art in that the condensing heat-exchange tube according to the present invention provides a larger heat transfer coefficient for the inner surface as well as the outer surface of the heat-exchange tube. Therefore, the heat transfer efficiency within the tube and outside the tube is enhanced, and the overall heat transfer efficiency is improved. The explanation is as follows. Secondary fins as well as third fins are provided on the fins arranged on the outer surface of the condensing heat-exchange tube according to the invention. Beside the fins, secondary fins and third fins further increase the heat transfer area for the heat-exchange tube. Meanwhile, secondary fins and third fins help to attenuate the condensate film such that the condensate film is substantially eliminated, and vapor condensation and heat discharge may be carried out in a better way. At the same time, secondary fins and third fins help to guide the condensate film away from the surface of the heat-exchange tube such that heat resistance may be reduced and temperature difference may be kept. Thus, the overall efficiency of heat transfer through condensation is enhanced, and the property of the condenser is improved. Inner teeth arranged on the inner surface of the tube are provided with substantially triangular configuration, and appropriate numbers of inner teeth are provided. Therefore, the heat transfer area for the inner surface of the heat-exchange tube is increased, and secondary turbulence is further developed in the cooling agent within the tube. Thus, the heat transfer efficiency within the tube is also enhanced.
Preferred embodiments of the present invention will be described in more detail with reference to accompanying drawings. The present invention relates to a condensing heat-exchange copper tube 100 for a flooded type electrical unit, which is developed based on a research on the heat transfer mechanism for a flooded heat-exchange tube, molding device and molding process thereof, and which has a size between 12 and 26 mm, is adapted to be used in electrical cooling condenser so as to achieve a higher heat transfer efficiency.
Referring to
Fins 31 are provided on the outer surface of the finned portion 3. Fins 31 are continuously arranged on the outer surface of the condensing heat-exchange tube 100 through a single spiral configuration, with an outer pitch angle β1 between 0.3° and 1.5°. The fin 31 comprises a fin base 311 and a fin top 312. A cross-section of the fin base 311 defines a rectangular, with a smooth transaction with the outer surface of the tube. A cross-section of the fin top 312 defines a trapezoid with a shorter top edge and a longer bottom edge, preferably an isosceles trapezoid. The wall thickness Tf of the finned portion 3 is between 0.5 and 0.9 mm. The height H1 of the fin 31 is between 0.7 and 1.2 mm, the width L1 thereof is between 0.15 and 0.35 mm, and the number of fins FPI per inch is between 30 and 70. These fins 31 advantageously result in an increase of the heat transfer area for the condensing heat-exchange tube, a decrease in the height of the condensate film, and a change in the surface tension. Therefore, the condensate film gets thinner, the heat resistance decreases, and the heat transfer coefficient of the heat-exchange tube 100 increases.
Referring to
A fin 31 is further provided with a third fin 33. The third fin 33 is developed by stamping the fin 31 radially downwardly with a tool from the top surface of the fin 31. The third fin 33 is interposed between two adjacent secondary fins 32 along the axial direction of the heat-exchange tube 100, that is to say secondary fins 32 and third fins 33 are arranged in stagger manner, that is to say secondary fins 32 and third fins 33 are not provided on the same radial line. A third groove 331 is defined between the top surface of the third fins 33 and two adjacent fins 31. The height H3 for a third groove 331 is between 0.15 and 0.45 mm, while the width L3 for the third fin is between 0.15 and 0.35 mm. A third fin 33 is provided with a similar configuration with that of a secondary fin 32, i.e. a right triangle, with the longer leg perpendicular to the fin 31.
Inner teeth 35 are also provided on the inner surface of the condensing heat-exchange tube 100. Said inner tooth 35 has a substantially triangular cross-section, with both the top and the bottom of the tooth rounded. The inner teeth 35 are spirally arranged on the inner surface of the heat-exchange tube 100. The number of the inner teeth per inch is between 30 and 60, the height Rh of the inner tooth is between 0.2 and 0.4 mm, the pitch angle β for the inner tooth 35 is between 30° and 60°, and the addendum angle γ for the inner tooth 35 is between 30° and 60°.
Fins 31, secondary fins 32 and third fins 33 of a condensing heat-exchange tube 100 according to the present invention increase the heat transfer area for the heat-exchange tube 100, and the top structure of secondary fins 32 and third fins 33 facilitates attenuating or eliminating the condensate film such that vapor may be condensed more easily, as well as guiding the condensate film to flow away from the surface of the heat-exchange tube 100 such that heat resistance may be reduced and temperature difference may be kept. Therefore, vapor condensation and heat transfer may be carried out in a better way. Thus, the efficiency of heat transfer through condensation is enhanced, and the property of the condenser is improved. The inner tooth 35 is provided with a substantially triangular cross-section. Therefore, the heat transfer area for the inner surface of the condensing heat-exchange tube 100 is increased, and secondary turbulence is developed in the cooling medium within the condensing heat-exchange tube 100. Thus, the heat transfer efficiency within the tube is also enhanced.
Referring to the second embodiment of this invention shown in
The preferred embodiment disclosed above is in all aspects merely illustrative. An ordinary person skilled in the art may understand that amendments and modifications can be made without departing from the scope of the invention. All these amendments and modifications shall fall within the scope of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2005 1 0134632 | Dec 2005 | CN | national |
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