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Method for making brazed heat exchanger and apparatus

A technology of heat exchangers and heat conduction, applied in the field of manufacturing brazed heat exchangers including strengthening the boiling surface, can solve problems such as difficulties

Inactive Publication Date: 2006-08-02
UOP LLC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Maintaining the integrity and effectiveness of the EBL, especially the porous structure provided by the artificially bonded metal particles, is more difficult to achieve brazing during the second hotter heat treatment
This difficulty is due to the fact that there are no commercially available brazed heat exchangers with an EBL in the boiling channel

Method used

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  • Method for making brazed heat exchanger and apparatus
  • Method for making brazed heat exchanger and apparatus
  • Method for making brazed heat exchanger and apparatus

Examples

Experimental program
Comparison scheme
Effect test

Embodiment I

[0030] The enhanced boiling powder was obtained by mixing 83.6 wt-% Al3003 alloy, 8.4 wt-% brazing flux containing potassium aluminofluorate and 8.0 wt-% aluminum alloy 4047 brazing powder. A binder comprising 38 wt-% polyisobutylene sold by Clifton Adhesives under the trade designation CS-200 A3 and 62 wt-% hydrocarbon (VARSOL) light kerosene solvent was mixed and brushed onto a tri-tubular form comprising aluminum alloy 3003 on the wall. The enhanced boiling powder is then sprayed onto the binder and heated in nitrogen in a small furnace. Each coated tubular wall was heated to 621°C (1150°F) for 9 minutes. The binder and solvent evaporate and leave an EBL 0.3-0.4 mm (10-15 mil) thick. The resulting EBL has a porous structure and was determined to have a mass greater than 204,418 kJ / hr / m 2 K(10,000BTU / hr / ft 2 °F) boiling heat transfer coefficient.

Embodiment II

[0032] The two metal tubular walls were coated with the binder described in Example I and the enhanced boiling powder. Each metal tubular wall was heated to a brazing temperature of 623°C (1153°F) in a closed retort at about atmospheric pressure under a controlled nitrogen atmosphere and then cooled.

[0033] The first tubular wall was heated and cooled over a period of 48 minutes. The first tubular wall is tested and determined to have greater than 204,418 kJ / hr / m 2 K(10,000BTU / hr / ft 2 °F), which is large enough for a surface with an EBL. The first tubular metal wall is then subjected to a second calcination by heating the first tubular metal wall to 593°C (1100°F) and holding at that temperature for 24 hours before cooling, For vacuum brazing of the entire heat exchanger core. Visual observations indicated that the quality of the EBL was not affected. The first tubular metal wall was again measured and determined to have a mass greater than 204,418 kJ / hr / m 2 K(10,000BT...

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PUM

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Abstract

Disclosed is a heat exchanger comprising a boiling passage and cooling passage defined by opposite sides of metal walls. Layers of brazing material between the metal walls and a spacer member bond components of the heat exchanger together. An enhanced boiling layer (EBL) comprising metal particles bonded to each other and to a boiling side of the metal wall provides nucleate boiling pores to improve heat transfer. The EBL has a melting temperature that is higher than the melting temperature of the brazing material. Also disclosed is a process for assembling the heat exchanger.

Description

technical background [0001] The present invention relates to an improved method for manufacturing metal heat exchangers with high thermal conductivity. More specifically, the present invention relates to an improved method for manufacturing brazed heat exchangers including reinforced boiling surfaces. [0002] In cryogenic, smelting and chemical applications, heat exchangers used in reboiler-condensers generally come in two configurations. One type of heat exchanger currently in use is the vertical shell and tubular heat exchanger. In order to achieve a sufficiently high degree of heat transfer with relatively low temperature differences, an enhanced boiling layer (EBL) is used. EBLs generally have a structure that includes many pores that provide boiling nucleation sites, thereby promoting boiling. EBL is applied on the inside of each tube, and longitudinal grooves are provided on the outside of each tube to facilitate heat transfer. [0003] Enhanced boiling layers for h...

Claims

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Application Information

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IPC IPC(8): F28F13/18F28D9/00F25J3/00F25J3/04
CPCF28F13/18F25J2250/20F25J3/04412F25J2250/02F28D9/0062F25J2290/44F28F13/187F25J5/002F25J3/04406F25J2290/32F28F21/081F28F21/089F28F2275/04F28F2250/108Y10T29/4935F25J5/005F28D9/00F28F13/00
Inventor P·S·奥尼尔老·D·P·赫尔德T·J·戈德里
Owner UOP LLC
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