Heat exchange – With coated – roughened or polished surface
Reexamination Certificate
1999-12-21
2002-01-08
Atkinson, Christopher (Department: 3743)
Heat exchange
With coated, roughened or polished surface
C165S184000, C165S177000, C029S890048
Reexamination Certificate
active
06336501
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a tube having a grooved inner surface preferable for a heat exchanger tube for use of a condenser as well as an evaporator which are used in a heat exchanger of an air conditioner or the like and its production method, particularly to a tube having a grooved inner surface achieving high condensing performance and evaporating performance even in a region in which a flow rate of a refrigerant is small and its production method.
2. Description of Related Art
There has conventionally been used a tube having a grooved inner surface having a plurality of spiral grooves at an inner surface of a tube as a heat exchanger tube to promote heat exchanging performance in a heat exchanger such as an air conditioner or the like.
According to heat exchange operation of an air conditioner or the like, there is utilized latent heat in evaporating a refrigerant liquid or condensing a refrigerant gas and in order to promote evaporating performance, there is needed a structure in which the refrigerant liquid is spread over a total of inside of a heat exchanger tube to thereby cause evaporation over an entire heat exchanger surface. In the meantime, in order to promote condensing performance, there is preferably used a structure in which the refrigerant liquid condensed on the heat exchanger surface can easily be removed and the liquid is easy to collect to one location such that the heat exchanger surface is not covered again by the removed liquid.
In recent times, in the case of an air conditioner or the like, in order to achieve energy conservation, there has been requested high heat exchanger performance (evaporating as well as condensing) and accordingly, it is indispensable to use a high heat exchanger performance tube even under a condition of small running load, that is, even in a region of a small flow rate of the refrigerant.
There have conventionally been proposed heat exchanger tubes shown below as tubes having grooved inner surfaces in which the inner surfaces of the tubes are fabricated to promote the heat exchanger performance.
According to a heat exchanger tube described in Japanese Unexamined Patent Publication No. 4-158193, there are installed a plurality of kinds of spiral groove groups. These spiral groove groups are formed such that at least one or more of factors in a pitch of groove in respect of a tube axis direction among adjacent spiral grooves, dimensions of the groove, the shape of the groove and a twist angle of the groove group in respect of the tube axis direction, differs.
Further, according to a heat exchanger tube described in Japanese Unexamined Patent Publication No. 8-121984, there are installed a plurality of continuous fins formed not to intersect with each other in the tube axis direction, discontinuous fins formed contiguous to the continuous fins in a discontinuous or sawtooth-like shape along a longitudinal direction such that the discontinuous fins do not intersect with the continuous fins and grooves formed between the discontinuous fins and the continuous fins.
Furthermore, according to a heat exchanger tube with grooves crossing an inner surface which is described in Japanese Unexamined Patent Publication No. 8-178574, in which grooves are formed at an inner surface of the tube to be inclined by 7° through 25° to the tube axis and sub grooves are installed in parallel with the tube axis or burrs are installed at three-dimensional projections left among the main grooves and the sub grooves to thereby conduct flow of the refrigerant in the direction of the sub groove.
Still further, according to a heat exchanger tube having a grooved inner surface described in Japanese Unexamined Patent Publication No. 10-206060, there are installed a first and a secondgroove group having the same groove pitch in a tube circumferential direction and different twist angles and twist directions in respect of the tube axis direction, there are arranged a plurality of sets of a first and a second groove fabricating region formed with the first and the second groove groups with different widths and there are arranged linear groove regions extending in the tube axis direction among the respective groove fabricating regions.
However, there are problems shown below in the above-described conventional heat exchanger tubes. First, according to the heat exchanger tube described in Japanese Unexamined Patent Publication No. 4-158193, although the flow of the refrigerant liquid is not hindered, the pressure loss cannot sufficiently be reduced in evaporation and accordingly, the evaporating performance is deteriorated and since discharge performance of the condensing refrigerant liquid is not sufficient in condensation, the performance of bringing the heat exchanger surface in contact with the refrigerant gas is lowered to thereby deteriorate the condensing performance. Further, when spiral groove groups having the same twist angle in respect of the tube axis direction are provided over the entire inner surface of the tube, the condensing refrigerant liquid is liable to spread over the entire heat exchanger surface in condensation, the heat exchanger surface is covered by the condensing refrigerant liquid and the condensing performance is deteriorated.
Further, according to the heat exchanger tube described in Japanese Unexamined Patent Publication No. 8-121984 and Japanese Unexamined Patent Publication No. 8-178574, the heat exchanger surface is designed with continuous grooves as a reference and accordingly, when the heat exchanger tube is used for a condenser, a swirl flow of the condensed refrigerant gas is liable to produce along the grooves. As a result, it is difficult to procure a dry heat exchanger surface necessary for condensation and accordingly, a deterioration in the condensing performance is resulted. Accordingly, there is a drawback in which the heat exchanger tube is not preferable in a heat pump type air conditioner requesting the evaporating performance and the condensing performance.
Further, according to the heat exchanger tube described in Japanese Unexamined Patent Publication No. 10-206060, there poses a problem in which the evaporating performance is deteriorated since a swirl flow of the refrigerant is hindered by the grooves in the reverse direction under a condition of a small flow rate of the refrigerant.
As mentioned above, in any of the conventional technologies, there are advantages and disadvantages and the performance excellent both in the evaporating and the condensing cannot be ensured.
SUMMARY OF THE INVENTION
The present invention have been carried out in view of such problems and it is an object of the present invention to provide a tube having a grooved inner surface capable of achieving high condensing performance and high evaporating performance even in a region of a small flow rate of a refrigerant and preferable as a heat exchanger tube for a condenser and an evaporator and its fabrication method.
According to an aspect of the present invention, there is provided a tube having a grooved inner surface comprising spiral groove fabricating zones formed with spiral grooves at an inner surface of a metal or an alloy tube, intersecting groove fabricating zones arranged at regions different from regions of the spiral groove fabricating zones at the inner surface of the metal or the alloy tube and formed with intersecting groove groups intersected with pluralities of grooves, wherein singles or pluralities of the spiral groove fabricating zones and the intersecting groove fabricating zones are arranged alternately in an inner peripheral direction of the metal or the alloy tube and when a fabrication width of the spiral groove fabricating zone in the inner peripheral direction is designated by a notation W
1
and a fabrication width of the intersecting groove fabricating zone is designated by a notation W
2
, a ratio W
1
/W
2
of W
1
to W
2
falls in a range of 0.3 through 0.9 or 1.1 through 3.0.
According to the present invention, in the case in which the tube h
Hinago Nobuaki
Ishikawa Mamoru
Ozeki Kiyonori
Saeki Chikara
Atkinson Christopher
Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel Ltd).
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