Twisted tube heat exchanger and manufacturing method of twisted tube heat exchanger

Abstract

A twisted tube heat exchanger which can prevent corrosion of a brazed joined part of water tubing is provided. A twisted tube heat exchanger 1, comprises: water tubing 3 which is made of phosphorus deoxidized copper, and which is provided with plural rows of crests and valley bottoms on the circumference thereof in a continuous and spiral form for each row; refrigerant tubing 5 which is spirally wound up and secured along the shape of the crest and valley bottom on the circumference of the water tubing 3; and joint tubing 4 which is made of phosphorus deoxidized copper, and which is connected to an end of the water tubing 3, wherein a joined part between the water tubing 3 and the joint tubing 4 is brazed with a brazing material 2 of phosphorus copper filler metal containing 4.0 to 8.0 weight% of tin, and 6.8 to 8.0 weight% of phosphorus, but containing no silver.

Description

technical field [0001] The present invention relates to a twisted tube heat exchanger used in a heat pump water heater and a manufacturing method of the twisted tube heat exchanger. Background technique [0002] As a water-refrigerant heat exchanger used in a heat pump water heater, for example, a twisted tube heat exchanger is known. The twisted tube heat exchanger uses a twisted tube with a spiral groove on the outer periphery as a water pipe, and a refrigerant pipe is wound along the spiral groove on the outer periphery of the water pipe, and the water pipe and the refrigerant pipe are caulked. The heater exchanges heat between the water flowing in the water pipe and the refrigerant flowing in the refrigerant pipe. The spiral groove provided in the water pipe has the effect of generating eddy current on the water side to improve heat exchange performance. [0003] The water pipe of the water-refrigerant heat exchanger is connected with the external machine through the c...

AI Technical Summary

Problems solved by technology

In addition, if the low-melting-point brazing filler metal of the above-mentioned Patent Document 1 is used for joining water pipes, the brazing filler metal is selectively corroded because the phosphorus deoxidized copper tube used as the water pipe is inactive relative to the phosphor copper brazing filler metal.

Regarding this point, the above-mentioned patent document 2 discloses a method of using a brazing material added with Zn or Sn in order to prevent corrosion of the brazed portion, but the content of Zn and the content of Sn are not specified, so a perfect solution cannot be expected. Anti-corrosion effect

Images