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A separation wake zone behind a heat transfer tube in a heat transfer device of a heat exchanger or the like is reduced, whereby a heat transfer action of the heat transfer device can be augmented and a pressure loss thereof can be reduced. The heat transfer device of the heat exchanger has a linear

A separation wake zone behind a heat transfer tube in a heat transfer device of a heat exchanger or the like is reduced, whereby a heat transfer action of the heat transfer device can be augmented and a pressure loss thereof can be reduced. The heat transfer device of the heat exchanger has a linear or tubular heat transfer object (T) in heat transfer contact with a heat carrier fluid (A), and a heat transfer fin (F) integrally formed with the heat transfer object for heat transmission therebetween. The heat transfer fin is provided with a guide fin (10) positioned in vicinity of the heat transfer object, and the guide fin conducts the fluid to the rear of the heat transfer object, thereby reducing the separation wake zone behind the heat transfer object. A position (B) of separation point of the fluid is set to be at an angular position (β) equal to or greater than 90�� from a stagnation point (E) on the heat transfer object by setting of an attack angle, configuration, position and dimensional proportion of the guide fin.

대표청구항 ▼

The invention claimed is: 1. A heat transfer device having linear or tubular heat transfer objects which are in heat transfer contact with a heat carrier fluid, and heat transfer fins which are integrally formed with the heat transfer object for heat transmission therebetween, the heat transfer obj

The invention claimed is: 1. A heat transfer device having linear or tubular heat transfer objects which are in heat transfer contact with a heat carrier fluid, and heat transfer fins which are integrally formed with the heat transfer object for heat transmission therebetween, the heat transfer object having a circular cross-section, comprising: a pair of guide fins positioned on both sides of said heat transfer object in the vicinity of the heat transfer object, the guide fins being configured for delaying a position of separation of the heat carrier fluid, an upstream end of the guide fin being located on an upstream side of a center of the heat transfer object, a downstream end of the guide fin being located on a downstream side of the center, each of said guide fins having an upper edge in the form of a straight line or curved line gradually increasing in height in a direction of flow of said heat carrier fluid for generating a longitudinal vortex behind the guide fin, each of the guide fins having a base on a plane of said heat transfer fin and being oriented at an attack angle α in a range from 10�� to 60�� relative to the direction of flow of said fluid to define a fluid passage for the heat carrier fluid between the guide fin and the heat transfer object, the passage diverging toward an upstream side of the heat transfer object and converging toward a downstream side of the heat transfer object, an altitude (h) at a highest part of the guide fin being dimensionally set to be equal to or greater than one half of an interval (Pf) of said heat transfer fins, a length (L) of said base being greater than a radius (R) of the heat transfer object, a ratio of the length (L) the base to the altitude (h) at a highest part of the guide fin being set to be in a range from 2 to 7, the downstream end of the guide fin being spaced from the heat transfer object to form a narrow gap for spouting the heat carrier fluid therethrough, so that said fluid entering an area between said heat transfer objects is accelerated between the heat transfer object and said guide fin and conducted to the rear of said heat transfer object for reducing a separation wake zone behind said heat transfer object and generating, behind the guide fin, a swirl flow deflected in accordance with an obliquity of said guide fin. 2. A heat transfer device as defined in claim 1, wherein, in relation to the radius R of said heat transfer object, a ratio of a distance R' between said downstream end and the center of said heat transfer object is set to be in a range of R'/R=1.05˜2.6. 3. A heat transfer device as defined in claim 1, wherein said heat transfer object is a heat transfer tube through which a thermal medium fluid to be heated or cooled can be circulated, and said heat transfer fins are arranged in a lengthwise direction of the tube, spaced a predetermined distance from each other, so that the thermal medium fluid is cooled or heated by heat exchange between the thermal medium fluid in the tube and the heat carrier fluid flowing in close vicinity of the surfaces of the tube and the heat transfer fin; and wherein said guide fins are positioned symmetrically with respect to the tube. 4. A heat transfer device as defined in claim 1, wherein said guide fin has a triangular configuration which includes the base on the plane of said heat transfer fin. 5. An air-cooled type of heat exchanger comprising said heat transfer device as defined in claim 1, and a fan effecting compulsory draft of the heat carrier fluid, whereby noise caused in operation of the fan is diminished by reduction of pressure loss of said heat transfer device. 6. A method of controlling a position of separation in a heat transfer device which has linear or tubular heat transfer objects and heat transfer fins integrally formed with the heat transfer object for heat transmission therebetween, the heat transfer object having a circular cross-section, a heat carrier fluid being passed through a fluid passage formed between the heat transfer fins, comprising the steps of: disposing a pair of guide fins on both sides of said heat transfer object in the vicinity of said heat transfer object to generate longitudinal vortices behind said guide fins, the guide fins being configured for delaying a position of separation of the heat carrier fluid, an upstream end of the guide fin being located on an upstream side of a center of the heat transfer object, a downstream end of the guide fin being located on a downstream side of the center, each of said guide fins having an upper edge in a form of a straight or curved line gradually increasing in its height in a direction of flow of said heat carrier fluid for generating a longitudinal vortex behind the guide fin, each of the guide fins having a base on a plane of said heat transfer fin and being oriented at an attack angle α in a range from 10�� to 60�� relative to a direction of flow of said fluid to define a fluid passage for the heat carrier fluid between the guide fin and the heat transfer object, the passage diverging toward an upstream side of the heat transfer object and converging toward a downstream side of the heat transfer object, an altitude (h) at a highest part of the guide fin being dimensionally set to be equal to or greater than one half of an interval (Pf) of said heat transfer fins, a length (L) of said base being greater than a radius (R) of the heat transfer object, a ratio of the length (L) the base to the altitude (h) at a highest part of the guide fin being set to be in a range from 2 to 7, the downstream end of the guide fin being spaced from the heat transfer object to form a narrow gap for spouting the heat carrier fluid therethrough, and controlling a position (β) of a separation point of said fluid with respect to the heat transfer object to be in a range of angular position equal to or greater than 90�� from a stagnation point (E) on the heat transfer object by setting of an attack angle, configuration, position and dimensional proportion of the guide fin so that a swirl flow is generated behind said guide fin and that said fluid entering an area between said heat transfer object and the guide fin is accelerated therebetween and conducted to the rear of the heat transfer object. 7. A method according to claim 6, wherein in the disposing step, said guide fins are disposed in a direction of span of the heat transfer objects in symmetry and the attack angle (α) of said guide fin to a direction of flow of said heat carrier fluid is set to be a predetermined angle in a range from 10�� to 60��. 8. A method according to claim 6, wherein in the controlling step, the attack angle, configuration, position and dimensional proportion of said guide fin are so set as to generate said swirl flow deviating behind the guide fin in accordance with an obliquity of said guide fin. 9. A method according to claim 6, wherein said heat carrier fluid gradually accelerates while varying in its direction, as a width of a fluid passage gradually reduces between said heat transfer object and said guide fin in accordance with an obliquity of the guide fin; said heat carrier fluid spouts rearward through a narrow gap (13) for spouting said fluid to the rear of the heat transfer object; and a spouting flow through the gap is directed in a tangential direction of a close point (14) of the heat transfer object which opposes against the downstream end (12) of the guide fin. 10. A method according to claim 6, wherein in the controlling step, the position (β) of the separation point (B) is an angular position of the separation point with reference to said stagnation point (E) occurring at a position ranging from 100�� to 135�� with respect to the heat transfer object. 11. A method according to claim 6, wherein in the disposing step, said heat transfer objects are located in one of a staggered arrangement and an in-line arrangement, and said guide fins are provided only for a front-most row of said heat transfer objects. 12. A method according to claim 6, wherein in the disposing step, said heat transfer objects are located in one of a staggered arrangement and an in-line arrangement, and said guide fins are provided only for every two rows of said heat transfer objects, or for rows spaced a few rows thereof. 13. A heat transfer device having heat transfer tubes which are in heat transfer contact with a heat carrier fluid, and heat transfer fins which are integrally formed with the tubes for heat transmission therebetween, the tube having a circular cross-section, comprising: guide fins positioned on both sides of the tube, the guide fins being configured for delaying a position of separation of the heat carrier fluid, an upstream end of the guide fins being located on an upstream side of a center of the heat transfer object, a downstream end of the guide fins being located on a downstream side of the center, each of said guide fins having a triangular configuration which includes a base on a plane of said heat transfer fin and an upper straight edge gradually increasing in height in a direction of flow of said heat carrier fluid for generating a longitudinal vortex behind the guide fin, each of the guide fins being oriented at an attach angle of a in a range from 10�� to 60�� relative to a direction of flow of said fluid to define a fluid passage for the heat carrier fluid between the guide fin and the tube, the passage diverging toward an upstream side of the tube and converging toward a downstream side of the tube, a downstream end of the guide fin being spaced from a tube wall of the heat transfer tube to form a narrow gap for spouting the heat carrier fluid therethrough, wherein a close point located on said tube opposing against a rear end portion of the guide fin in a direction perpendicular to said heat carrier fluid is spaced a distance (S) from the rear end portion, an altitude (h) at a highest part of the guide fin being dimensionally set to be equal to or greater than one half of an interval (Pf) of said heat transfer fins, a length (L) of said base being greater than a radius (R) of the heat transfer object, and a ratio of the length (L) f the base to the altitude (h) at a highest part of the guide fin being set to be in a range from 2 to 7. 14. A heat transfer device as defined in claim 13, wherein said guide fins are positioned symmetrically with respect to the tube.