JPS61291990A - Heat exchanger tube - Google Patents

Abstract

PURPOSE:To obtain a heat exchanger tube having a boiling heat transfer accelerating effect by forming an uneven metallic layer on the surface of the inner wall of a group tube by plating with a plating soln. contg. an oxyethylene surfactant and low concn. chloride ions so as to increase the surface area. CONSTITUTION:An uneven metallic layer 5 of copper or the like having superior adhesion is uniformly formed on the surface 4 of the inner wall of a group tube having heat radiating fins 3 for a heat exchanger 1 by plating with a plating soln. contg. an oxyethylene surfactant such as polyoxyethylene oleyl ether and low concn. chloride ions as additives. The surface area is increased and a heat exchanger tube having a boiling heat transfer accelerating effect is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a heat exchanger tube used in a heat exchanger or a heat vibrator, particularly for flowing a liquid medium.

Conventional technology It is generally known to increase the surface area and promote boiling heat transfer by forming a porous layer in a heat exchange member, but it is not possible to form a porous layer in a heat exchanger tube using the sintering method. Since it is difficult to do so using the irradiation method or the radiation method, a plating method is usually used. However, the plating method used to increase the surface area and measure the effect of promoting boiling heat transfer requires processing under conditions different from those for smooth plating, and it is necessary to finish the plating layer with appropriate porousness and protrusions. .

The method for forming such a plating layer is to avoid adding complex salts, glue-like substances, brighteners, additives for making crystal fine particles, etc. to the plating solution, which are necessary to obtain normal smooth plating. A very small amount of plating solution is used, the plating conditions are generally high temperature and high current density, and the plating solution is formed by high-speed fluid stirring.

Problems to be Solved by the Invention However, even if the plating solution is introduced into the inner wall surface of the heat transfer tube under these conditions, the plating solution will be unstable if carried out at high temperature and high current. It is difficult to achieve uniform porous plating to the inside, as metal precipitates locally in areas where the spacing between electrodes is small, and the plating solution conditions are unstable due to the lack of complex salts, resulting in a short period of time. Not only does it decompose over time, making it unsuitable for mass production, but the adhesion between the wall surface of the heat exchanger tube vibrator and the plating layer is also insufficient, and when the liquid medium flows, There were problems such as the plating layer peeling off due to shock or shock.

In view of the above-mentioned problems, the present invention provides a heat transfer tube having a heat transfer wall surface that forms a uniform and highly adhesive uneven plating layer, increases the surface area, and is effective in promoting boiling heat transfer. It is.

Means for Solving the Problems In order to solve the above problems, the heat exchanger tube of the present invention contains polyoxyethylene oleyl ether, which is an oxyethylene surfactant, and an appropriate concentration of chloride in the plating solution. An uneven plating layer is formed on the inner wall surface of the group tubes by electroplating using a plating solution containing ions as an additive and using the heat transfer tube side as a cathode.

Effect The present invention has the above-described structure, so that the metal ions that are captured and complexed by the molecules of polyoxyethylene oleyl ether, which is an oxyethylene surfactant in the plating solution, are removed in the presence of a low concentration of chloride ions. , works to form an uneven plating layer by unstably combining with chloride ions. In other words, there is no need for an unstable plating solution with few complex salts or a plating method under excessive conditions, so there is less decomposition of the plating solution, and the adhesion between the plating layer and the wall surface of the heat transfer tube is good. , the surface area is significantly increased compared to ordinary smooth tubes, and the effect of promoting boiling heat transfer can be measured.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to FIGS. 1 to 4.

Reference numeral 1 denotes a heat exchanger, which consists of a group tube 2 made of a copper vibrator with grooves formed on its inner surface and a heat dissipation fin 3 made of thin aluminum. An uneven metal plating layer 5 made of copper is formed on the inner wall surface 4 of the group tube 2. Also, both ends 6a of this group tube 2.

6b is completely sealed by caulking and welding, and fluorocarbon gas is sealed inside. 7 is a plating layer whose temperature can be controlled by a heater 8, into which a plating solution 9 is placed.
u 3o 4 ・5H20,0,5moQ/ j2 H
2So4, 0.33 x 10-' m
oQ/ρ 1-tcp and 19u/ρ polyoxyethylene oleyl ether. Reference numeral 10 denotes a group tube before both ends 6a and 5b are sealed, and by combining a connecting tube 11 and a circulation pump 12, the plating solution 9 is circulated inside the group tube 10.

Incidentally, the heat dissipation fins 3 have already been installed using a tube expander (
It is fixed to the outer periphery of this group tube 10 by expanding the tube with a tube (not shown). Furthermore, in the connecting pipe 11,
A counter electrode 14, which is a titanium rod plated with platinum and is directly connected to a DC power supply 13, and a connecting terminal 15 to which a charge opposite to that of the counter electrode 14 is applied are fixed. group tube 10
A non-conductor spacer 16 made of polypropylene is inserted into the group tube 10 in order to prevent contact between the connection terminal 15 and the group tube 1G when the connecting tube 11 and the connecting tube 11 are connected using the connecting terminal 15. . Also, 17 is plated 'I & 9
It is an air pump that blows air into.

Next, a method for manufacturing a heat exchanger with such a configuration will be described.

First, the group tube 10 and the radiation fin 3 are temporarily fitted in a fixed position, and the group tube 10 is expanded using a predetermined tube expander (not shown), and the group tube 10 and the radiation fin 3 are crimped together. I'll keep it. Next, the group pipe 10, the connecting pipe 11, and the circulation pump 12 are combined, and the plating solution 9 in the plating bath 7 is circulated inside the group pipe 10 by the operation of the circulation pump 12. At this time, plating solution 9 and t, 4+, t
O,6mo4/j2 CU 3o 4 -5H20,
0,510ρ/ρ H2804, 0,33xlo-3n
oρ/ρ HCρ, 19u/Q An acidic copper sulfate plating solution containing polyoxyethylene oleyl ether is used. Therefore, the DC power supply 13 applies a positive charge to the counter electrode 14, which is a titanium rod plated with platinum, to make it the anode side, and a negative charge is applied to one of the connection terminals 15, making it the horn sword side. The current value at this time is approximately 200mA/cd, approximately 2
Turn on electricity for 0 minutes. Further, the plating solution 9 was heated by the heater 8 of the plating tank 7 to about 50°C.

Here, if a normal plating solution is used, copper will be deposited in a uniform thickness on the entire inner wall surface of the group tube 10 on the cathode side, but the plating solution 9 contains polyoxyethylene, which is an oxyethylene surfactant. Since it contains ethylene oleyl ether and chlorine ions generated by a low concentration of hydrochloric acid, the copper metal plating layer 5 does not have a uniform thickness over the entire surface, but an uneven metal plating layer 5 is formed. The reason for this is
This is because copper ions, which are captured and complexed by the molecules of polyoxyethylene oleyl ether, which is a surfactant, combine unstablely with chlorine ions in the presence of a low concentration of chlorine ions.

Next, the inner wall of the group tube 10 is washed with hot water, and after drying, Freon gas is sealed inside, and both ends 6a are sealed.

By caulking and welding 6b, the heat exchanger 1 having the heat transfer tubes 2 and the radiation fins 3 is completed.

In the heat exchanger 1 obtained in this manner, since polyoxyethylene oleyl ether, which is a surfactant in the plating solution, and the salt content are specified, the uneven inner wall surface 4 of the group tube 10 is further coated. The metal plating layer 5 with dendritic irregularities is formed densely, and the synergistic effect of the irregularities of the group tube 10 and the irregularities of the metal plating layer 5 not only increases the surface area but also makes the dendritic metal plating dense. Because of this, the uneven metal plating layer 5 serves as a boiling nucleus for boiling heat transfer, and can be more effective in promoting boiling heat transfer than ordinary needle-like uneven plating. Furthermore, when the fluorocarbon gas liquefies on the inner wall surface 4, the liquid layer turns into droplets on the convex portions of the uneven metal plating layer 5, and separates from the inner wall surface 4 faster than a smooth surface, resulting in a liquid layer that is a thick heat insulating layer. Since no is formed, heat transfer during condensation is also promoted. That is, it is possible to obtain a heat exchanger 1, which is a heat pipe-like heat pipe in which liquefied fluorocarbon gas is sealed and repeats evaporation and condensation, with significantly improved heat transfer efficiency.

Furthermore, the uneven metal plating layer 5 on the inner wall surface 4 of the heat exchanger tube 2 has a dense dendritic metal plating formed by the method described above.
Since this method does not require an unstable plating solution with few complex salts or a plating method under excessive conditions, there is little decomposition of the plating solution 9, its hardness and tightness are very good, and it can always be used to stabilize uneven metals. A plating layer 5 is formed.

In the embodiment of the present invention, an acidic copper sulfate plating solution was used as a means for forming the uneven metal plating layer 5, but although copper is advantageous in terms of thermal conductivity, other metal plating solutions may also be used. Yes, but not limited to copper plating. Furthermore, regarding hydrochloric acid, it is possible to use chloride such as Na (4), which contains all the chloride ions that are released as chloride ions in the plating solution. However, if the chloride ion concentration is greater than 1 mmol/ρ, unevenness may occur. Although the metal plating layer 5 is formed, since the density of the plating becomes sparse, the chlorine ion concentration must be kept at 1 mmol/Ω or less.

Although polyoxyethylene oleyl ether was used as a surfactant, all oxyethylene surfactants such as polyethylene glycol and polyododiethylene noryl phenyl ether are included.

Effects of the Invention As described above, the present invention forms an uneven metal plating layer on the wall surface of the group tube using a plating solution containing an oxyethylene surfactant and a low concentration of chloride ions as additives. Since it is a heat exchanger tube, the following effects can be obtained by 1q.

(a) Dendritic plating is densely formed on the uneven plating layer on the inner wall surface of the group pipe, and this not only further increases the surface area due to the synergistic effect of the unevenness of the group pipe and the unevenness of the plating layer, but also causes dendrites to form. Since the shaped plating is densely formed, the uneven plating layer becomes a boiling nucleus for boiling heat transfer, and can be more effective in promoting boiling heat transfer than normal needle-like uneven plating.

(b) Regarding heat transfer during condensation, when the fluorocarbon gas liquefies on the inner wall surface of the heat exchanger tube, the liquid layer becomes droplets on the convex parts of the uneven plating layer and separates from the inner wall surface faster than the smooth surface. Since a thick insulating liquid layer is not formed, heat transfer during condensation is also promoted.

(C) The uneven plating layer formed on the inner wall surface of the heat exchanger tube is
Since it does not require an unstable plating solution with few complex salts or a plating method under excessive conditions, there is little decomposition of the plating solution, its hardness and adhesion are very good, and a stable, uneven plating layer is always formed. be done.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, in which Fig. 1 is a cross-sectional view of a heat exchanger, Fig. 2 is a longitudinal sectional view of the heat exchanger, Fig. 3 is a perspective view of the heat exchanger, and Fig. 4 is a cross-sectional view of the heat exchanger. It is a schematic diagram of a plating apparatus. 1... Heat exchanger, 2.10... Group tube, 5...
・Uneven metal plating layer, 9...Plating solution, agent Yoshihiro Morimoto Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. Group A heat exchanger tube formed by forming an uneven metal plating layer on the tube wall surface using a plating solution containing an oxyethylene surfactant and a low concentration of chloride ions as additives.