1. The Field of the Present Disclosure
This invention involves the technical field of heat-transfer tubes, especially a type of enhanced condensation heat-transfer tube.
2. Description of Related Art
With the concept of energy conservation and high efficiency being widely promoted, requirements for heat transfer performance in condenser design has gradually increased and a highly-efficient heat-transfer tube is the key factor affecting the heat transfer performance of a condenser. A Chinese patent document, with publication number of CN1982829A, discloses a type of copper heat-transfer tube with triangular smooth fins on the outside. Such smooth fins increase the heat transfer area. When used in a condenser, it reduces condensate membrane and accelerates condensate dripping. Thus, it is of higher heat transfer efficiency than a smooth tube. However, a smooth fin easily enables “bypass” of condensate and renders the condensate to flow less smoothly. As a result, condensation thermal resistance of the fins increases and the heat transfer efficiency is reduced. Another Chinese patent document, with the publication number CN101813433A, discloses another type of heat-transfer tube, for which a top slotted fin structure is adopted. Its serration structure may pierce through the condensate membrane and the fin platform can enhance condensation heat transfer performance to a certain extent.
Structures of the said heat-transfer tube of condensers in current use are shown in
The features and advantages of the present disclosure will be set forth in the description which follows, and in pal will be apparent from the description, or may be learned by the practice of the present disclosure without undue experimentation. The features and advantages of the present disclosure my be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims.
The features and advantages of the disclosure will become apparent from a consideration of the subsequent detailed description presented in connection with the accompanying drawings in which:
This invention solves the technical problem of low efficient heat transfer performance by providing an enhanced condensation heat-transfer tube with improved heat transfer performance.
To solve the above problems, the present invention discloses a type of enhanced condensation heat-transfer tube, which is furnished with spiral fins on the outer surface and features regular changes in axial direction and in the width of spacing between the said fins.
In preferred embodiments, for the said spiral fins, smooth fins are used; or slotted fins, formed by grooving on the top or both sides of smooth fins, are used.
In preferred embodiments, 26 to 60 of said spiral fins are arranged every inch along the axle and the axial spacing between the fins ranges from 0.4 to 1 mm.
In preferred embodiments, spacing between the said fins changes along the axle with alternating wide spacing and narrow spacing; or spacing between the said fins changes along the axle with alternating one wide spacing and two narrow spacing; or spacing between the said fins changes along the axle with alternating two wide spacing and one narrow spacing.
In preferred embodiments, the height of the said spiral fins regularly changes in the axial direction.
in preferred embodiments, the said spiral fins are 0.1 to 0.4 mm thick with their heights ranging from 0.4 to 1.5 mm.
In preferred embodiments, the height of the said spiral fins regularly changes along the axle with alternating one high fin and one short fin; or the height of the said spiral fins regularly changes along the axle with alternating one high fin and two short fins; or the height of the said spiral fins regularly changes along the axle with alternating two high fins and one short fin.
In preferred embodiments, the helical angle of the said spiral fins ranges from 0.3° to 1.5°.
In preferred embodiments, a threaded ridge is provided on the inner surface of the said heat-transfer tube.
In preferred embodiments, the angle between the said threaded ridge and the axle ranges from 30° to 60°; there are 6 to 60 internal threads on the threaded ridge, with heights ranging from 0.1 to 0.6 mm.
Compared to existing technologies, this invention is advantageous in the following aspects:
The preferred embodiments of this invention disclose that the spacing between the fins on the outside surface of the enhanced condensation heat-transfer tube and the height of the fins vary. Surface tension of the condensate changing evenly can be put into full utilization to reduce the thickness of the condensate membrane. Uneven distribution of thickness in condensate membranes may reduce average heat resistance and enhance the “Gregorig” effect, so as to increase the coefficient of heat transfer on the outer surface of the heat-transfer tube. At the same time, even changes in surface tension and variation of the curvature reduce the retention of the condensate and accelerate its dripping so as to improve heat transfer performance and mitigate the “tube bundle effect”. Heat transfer efficiency inside and outside of the tube provides optimal combination to increase the overall heat transfer efficiency of the enhanced condensation heat-transfer tube.
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The above embodiments of this invention can be combined to have different shapes of fins with their spacing and height varying.
In addition, in the above preferred embodiments of this invention, dedicated equipment can be used to acquire a threaded ridge 1 in the tube so as to improve the coefficient of heat transfer in the tube. The angle between the threaded ridge 1 and the axle is from 30° to 60°; there are 6 to 60 internal threads, and the ridges are 0.1 to 0.6 mm high. Threaded ridge 1 may damage the boundary of the fluid in the tube and increase disturbance to fluid in the tube, so as to enhance heat transfer and improve the coefficient of heat transfer in the tube.
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The specific structure of the enhanced heat-transfer tube for condenser as described in this invention will be introduced in the following in combination with specific embodiments:
When the enhanced condensation heat-transfer tube described in this invention is processed and manufactured as per the structure shown in
In addition, dedicated equipment will be used to process a threaded ridge 1 on the inner surface of the tube to improve the coefficient of heat transfer outside and inside the tube. In the seventh embodiment of this invention, the threaded ridge 1 is 0.38 mm high, the angle between the ridge and the axle is 42°, and there are 45 threads.
According to statistics obtained from actually measured data, when refrigerant R134a is used, the condensation heat transfer performance of this invention is 12% higher compared with existing technologies.
In the above embodiments of this invention, considering the heat transfer performance and cost performance of metal materials, copper is preferred to make this condensation heat-transfer tube. Other metal materials such as copper alloy, aluminum, aluminum alloy, low carbon steel, and copper and aluminum composite can also be used.
All embodiments in this Specification are described in a progressive manner. Description of each embodiment is emphasized on its difference from other embodiments and reference can be made to each other for the identical and similar parts of the embodiments.
This summary introduces in detail a type of enhanced condensation heat-transfer tube provided in this invention. It elaborates the principles and implementation methods of this invention through specific examples. Description of the above embodiments is merely used to help understand the core idea of this invention. At the same time, common technicians in this field may change the specific embodiment methods and application scope in line with the idea of this invention. To sum up, the contents of this Specification shall not be construed as the limit to this invention.
Number | Date | Country | Kind |
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20120181289.2 | Jun 2012 | CN | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/CN2013/070226 | 1/8/2013 | WO | 00 | 12/11/2013 |