JP7079395B2 - A three-dimensional three-dimensional element for promoting heat transfer and a heat exchanger in which the element is inserted inside a heat transfer tube. - Google Patents

Description

The present invention relates to a tube-side heat transfer promoting three-dimensional element of a heat exchanger having improved heat transfer performance.

The so-called shell-and-tube (body & tube: multi-tube cylindrical) type heat exchanger is very useful for heat recovery in the industrial field, and some devices for improving its heat transfer efficiency have been proposed.

To increase the overall heat transfer coefficient of the heat exchanger, it is necessary to increase the flow velocity in order to increase the boundary film heat transfer coefficient between the tube side and the body side, that is, to increase the Reynolds number, and the body side is based on the baffle. The design has been optimized, such as increasing the cross path and increasing the number of paths on the pipe side.

A three-dimensional metal wire three-dimensional element (trade name: Hytran) has been proposed as one of the means for achieving heat transfer promotion on the pipe side without increasing the flow velocity on the pipe side, and is widely used for industrial purposes.

This metal wire three-dimensional element is provided individually according to the inner diameter of the heat transfer tube, the minimum diameter is 6 mmΦ, and in order to insert it into the heat transfer tube, a jig is used in advance to determine the diameter of the element. It is necessary to narrow down.

It is thought that the principle of heat transfer promotion of the three-dimensional solid element is to break the liquid film staying on the inner wall of the circular tube with the loop metal wire in contact with the wall surface to form a pseudo turbulent flow, and the loop-shaped wire is the wall surface. It is important to be in contact with.

Therefore, the outer diameter of the loop wire of the three-dimensional solid element is manufactured to be slightly larger than the inner diameter of the heat transfer tube used, and after being narrowed down at the time of insertion, it adheres to the inner wall of the heat transfer tube by the restoring force of the metal wire. There is.

The actual high-tran loop wire is tilted and fixed to the core wire so that it is narrowed down in one direction, and the three-dimensional element inserted in the heat transfer tube is relatively easy in the direction to narrow down this tilt. It can be pulled out, but in the opposite direction it cannot be pulled out without destroying its structure.

That is, in order for the metal three-dimensional element to exert the heat transfer promoting effect, it is necessary to use a loop wire having an outer diameter several percent larger than the inner diameter of the heat transfer tube, and the smaller the percentage is, the smaller the inner diameter of the heat transfer tube is. If it is not reduced, the frictional resistance at the time of insertion will increase, and the workability of insertion will deteriorate.

For example, the loop outer diameter of a metal three-dimensional solid element used for a heat transfer tube with a nominal diameter of 25 A should have a loop wire that is about 10% larger than the inner diameter, and at the time of insertion, use a jig below the inner diameter of the heat transfer tube to remove the loop wire. The diameter can be narrowed down and the wire can be brought into close contact with the tube wall by the restoring force of the wire after insertion.

However, as the size of the heat transfer tube becomes smaller, the processing accuracy of the loop outer diameter is required to be higher, and the smallest metal three-dimensional element actually supplied is for a heat transfer tube with an inner diameter of 6 mmΦ. Nothing less than this is available.

Furthermore, since the restoring force of the metal loop wire is limited, it is necessary to create a metal three-dimensional element according to the inner diameter.For example, assuming that an element for an inner diameter of 6 mmφ is inserted into a heat transfer tube with an inner diameter of 8 mmφ. However, since there is no contact with the inner wall of the pipe, its heat transfer promoting effect is limited.

If the body diameter is the same, the smaller the inner diameter of the heat transfer tube, the larger the heat transfer area, but it becomes difficult to process the head. / We are proposing a small heat exchanger that separates the fluid in the cylinder.

Japanese Unexamined Patent Publication No. 2018-151104

Watanabe, Sakai, "Utilization of tube-side three-dimensional wire element" hiTRAN "that promotes heat exchanger transmission (No. 5)", Chemical Equipment, Kogyo Tsushin Co., Ltd., June 2016, Vol. 58, No. 6 , P64-69.

An object of the present invention is to provide a structure of a three-dimensional heat transfer promoting three-dimensional element that can be easily inserted into a small-diameter heat transfer tube using Tegs for a loop wire that contacts the inner wall of the tube, and a method for manufacturing the element. This is to achieve the configuration of a high-efficiency compact multi-tube cylindrical heat exchanger.

Since the loop wire of the three-dimensional heat transfer promoting element of the present invention has a supple Tegs, when it is inserted into a heat transfer tube having an inner diameter of 10 mmφ or less, it can be inserted with less force than that of a metal loop wire. Unlike the high-tran, it is not necessary to narrow down the loop portion before insertion, and it can be inserted and removed regardless of the insertion direction.

Specifically, the three-dimensional element having an outer diameter of 8 mm for the loop wire of the present invention is used for an inner diameter of 7 mmφ of a heat transfer tube, but at the same time, it can be easily inserted into a heat transfer tube having an inner diameter of 5 mmφ, so that it is a conventional metal loop. The range of the inner diameter of the heat transfer tube that can be applied is wider than that of a three-dimensional element having a wire, which is considered to be due to the small deformation stress and frictional resistance of the loop wire.

The loop-shaped fishing line used in the present invention is No. 1.5 (0.205 mmφ) to No. 10 (0.520 mmφ), and the heat transfer tube with an inner diameter of 4 to 7 mm is No. 3 (0.285 mmφ) or No. 4 (0.330 mmφ). preferable. The material of Tegs is preferably nylon yarn, fluorocarbon yarn, polyester yarn, polypropylene yarn, polyphenylene sulfide yarn, and fluorine yarn.

For the metal core wire for twisting and fixing the loop-shaped fishing line, for example, SUS304 # 20 to # 22 (0.9 to .66 mmφ) is suitable.

Before fixing the spiral loop-shaped fishing line to the metal core wire, the fishing line must be fixed in a spiral loop shape. It is annealed at a temperature lower than the softening temperature to form a spiral loop.

A metal core wire is passed through this Tegs spiral loop, folded in half, and then twisted to manufacture the heat transfer promoting three-dimensional element of the present invention.

As a result of making a prototype of a heat exchanger in which the element was inserted into a heat transfer tube and comparing the heat exchange capacities, the heat transfer promoting effect was equivalent to that of Hytran.

Schematic diagram before twisting through a Tegs fixed in a spiral loop and a metal core wire. A photograph of the number of twists and changes in the shape of the core wire. A photograph of the body of the heat exchanger that evaluated the heat transfer promotion performance.

Hereinafter, embodiments of the present invention will be shown, and the effects thereof will be described with reference to Examples.

Nylon No. 3 (0.285mmφ) Tegs was fixed around an aluminum tube with a diameter of 3mmΦ, and a single-wound 30cm spiral loop Tegs rod was created.

At this time, the total length of the wound line was 8 m, and the number of turns was 850, which was 80% of the theoretical close-packed number.

It was soaked in boiling water for 5 minutes for annealing the Tegs wrapped around this rod.

After cooling, attach the # 20SUS core wire for twisting to the end, and then open both ends of the Tegs wound around the rod, the spiral diameter will be about 5 mm and the core wire as shown in Fig. 1 will be formed. A spiral loop of passed Tegus was obtained.

After folding the SUS core wire in half, the open end was fixed, and the bent part on the opposite side was hooked on the hook of the machine from the rotating string and twisted to fix the spiral loop tegs to the core wire.

FIG. 2 is a photograph showing the number of twists of the core wire at the metropolitan stage and the fixed state of the spiral loop teg. In the present invention, the spiral loop teg is finally twisted until it is firmly fixed to the core wire. be.

The spiral loop fishing line in Fig. 1 is attached to one side of the core wire, but the fishing line is placed on the folded side and can be twisted.

In order to confirm the heat transfer performance of the three-dimensional heat transfer promoting three-dimensional element of the present invention manufactured in this way, two types of small heat exchangers were manufactured and the heat transfer promotion performance was measured.

The small heat exchanger is a 320 mm long heat exchanger with 30 aluminum pipes with an inner diameter of 5 mmφ and a thickness of 0.5 mm mounted on a PVC pipe with an inner diameter of 52 mmφ. The number of fluid paths in is one countercurrent path.

The outside of the aluminum heat transfer tube is a plain with nothing to be a baffle, and two types of twisted wires are prepared, in which two twisted 1 mm aluminum wires are spirally wound 10 times in anticipation of a swirling flow on the body side. did.

Figure 3 is a photograph in which both ends are sealed and a heat transfer promoter is inserted. The left side is a plain, the right side is a twisted wire, and the head for a pipe is attached to this to complete the heat exchanger.

In order to confirm the effect of the three-dimensional heat transfer promoting three-dimensional element of the present invention, the heat exchange performance was measured between the heat exchanger in which the element was inserted and the case where the element was not inserted (empty).

The fluids that exchange heat are water at 20 ° C and 38 ° C, and the flow rate is 6 L / min on the low temperature side and 10 L / min on the high temperature side. rice field.

As a result, when the body side was plain, the emptyness was 2.1 kW, whereas when the element of the present invention was inserted, the heat exchange performance was observed to be 3.3 kW, which is a 160% increase in heat exchange performance.

In the case of a heat exchanger equipped with a twisted wire on the body side, the emptyness was 3.0 kW, whereas when the element of the present invention was inserted, it was 4.3 kW, an increase of 143% was observed.

As described above, it was confirmed that the three-dimensional heat transfer promoting three-dimensional element using the Tegs of the present invention as a loop wire reduces the heat transfer resistance on the tube side and improves the heat transfer performance by about 50%.

Development of energy-saving technology is desired to prevent global warming, but high-efficiency heat recovery technology from low-temperature wastewater is desired, and a heat exchanger equipped with the three-dimensional three-dimensional element for heat transfer promotion of the present invention is desired. Is expected to make a great contribution.

Claims (4)

A three-dimensional heat transfer promoting three-dimensional element placed inside a heat transfer tube with an inner diameter of 26 mmφ or less. A plastic spiral loop made of Tegs with a diameter of 0.1 to 1.0 mm and a loop diameter of 3 to 15 mm. A three-dimensional element for heat transfer , characterized in that the plastic spiral loop is fixed to the core wire by folding the metal core wire passed through the inside of the core wire in half and further twisting the metal core wire. ..
The three-dimensional element for heat transfer according to claim 1, wherein the material of the Tegs is a nylon thread, a fluorocarbon thread, a polyester thread, a polypropylene thread, or a polyphenylene sulfide yarn. A heat exchanger in which the heat transfer promoting three-dimensional element according to claim 1 or 2 is inserted in the heat transfer tube. Pass the metal core wire through the inside of the plastic spiral loop made from Tegs molded with a diameter of 0.1 to 1.0 mm and a loop diameter of 3 to 15 mm, fold the metal core wire in half, and twist it further. A method for manufacturing a three-dimensional three-dimensional element for promoting heat transfer, which comprises fixing the plastic spiral loop to the metal core wire.

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