Heat transfer pipe for heat exchanger

Abstract

The invention provides a heat transfer pipe for heat exchanger, an inner surface of the heat transfer pipe being provided alternately with a plurality of helical primary teeth (21, 22, 23, 24, 25, 26, 27) and a plurality of grooves (31, 32, 33, 34, 35, 36), each groove being disposed between adjacent primary teeth, wherein a protrusion set is provided in at least one groove (31, 36), the protrusion set comprises a plurality of protrusions (41) sequentially and intermittently disposed in an extending direction of the primary teeth, and each protrusion (41) has a radial height lower than those of the primary teeth, and wherein at least one groove having no protrusion set (32, 33, 34, 35) is provided between the adjacent ones (31, 36) of the grooves each having a protrusion set. In this way, the above heat transfer pipe suppresses significantly increasing flow resistance of a fluid, and is easy to manufacture with low manufacturing cost, at the same time of improving the efficiency of heat exchange.

Description

TECHNICAL FIELD[0001]This invention relates to a heat transfer pipe for heat exchanger, more particularly to a heat transfer pipe with helical rifling or helical primary teeth.BACKGROUND[0002]A heat exchanger is an apparatus that makes it possible to exchange energy between two or more fluids for the purpose of heating, cooling and etc. In a heat exchanger regularly used nowadays, fluids under heat exchange are separated from each other with a solid dividing wall or a third fluid. The design of the heat transfer pipe for the heat transfer has great influence on the operating efficiency of the heat exchanger.[0003]FIG. 1 shows a typical heat transfer apparatus 100, which comprises a plurality of fins 101 and a plurality of heat exchange pipes 102. Lines of holes are provided in the fins 101, and the heat exchange pipes are inserted into these holes. During operation, a first fluid enters into the heat transfer pipe system comprising the plurality of heat exchange pipes 102, as the ar...

AI Technical Summary

Benefits of technology

[0007]The invention, intending to solve the aforementioned problems, provides a heat transfer pipe for heat exchanger, which can improve the heat transfer efficiency while not significantly increasing the transfer resistance to a fluid, and has a simple structure as well as low manufacturing cost.

[0010]With the above heat transfer pipe, on the one hand, the presence of the protrusions enhances the fluid (such as cooling agent or cold media) turbulence evoked by the bottoms of the primary teeth, and assists in forming more cores for bubbles during evaporation, and thus improves the efficiency of heat exchange; on the other hand, not all, but every few, grooves between the primary teeth are provided with protrusions, which suppresses significantly increasing flow resistance of a fluid, avoids too great a pressure decrease, and at the same time results in low manufacturing cost.

[0011]Preferably, the width of each protrusion in the circumferential direction of the heat transfer pipe is smaller than the width of the groove where the each protrusion is located in the circumferential direction of the heat transfer pipe. This further reduces the resistance of protrusions to a fluid. Moreover, a protrusion is only provided on part of the wide of a groove in the circumferential direction, which further destructs the formation of the boundary layer of a fluid, enhances the turbulence, and thus improves the effect of heat exchange.

[0014]Preferably, section of each protrusion that is perpendicular to the circumferential direction of the heat transfer pipe is a trapezoidal. The ratios of the radial height of each protrusion to the radial heights of the primary teeth can be between 0.05-0.5. The protrusions configured according to such preferred embodiments are more advantageous for formation of cores for condensing or vaporization and enhances the turbulence.

[0016]According to one embodiment, the radial height of each protrusion is gradually decreased from the side of the protrusion that is formed on a side surface of a primary tooth and in the extending direction of the primary tooth. The protrusion thus formed leads to less resistance to a fluid and avoidance of too great a pressure decrease, which improves the operating efficiency of the whole heat exchanger. Particularly, the protrusions can be formed into such shapes as sickles, crescents, horns, or the similar.

Problems solved by technology

On the basis of this, some heat transfer pipes are provided with, in addition to the primary teeth, intermittent secondary teeth with lower heights and disposed between the primary teeth, which results in further increasing the roughness within the heat transfer pipes.

Moreover, the shaping and positioning of the secondary teeth is not optimized with regard to the kinetics of the fluid, it is thereupon inconvenient to manufacture, which, de facto, raises the cost of manufacturing.

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