TED-AJ03-236 GAS-LIQUID FLOW DISTRIBUTION IN MULTIPLE-PASS FLAT CHANNELS WITH NARROW CLEARANCE

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概要

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• In compact heat exchangers accompanied by gas-liquid phase change phenomena, small refrigerant passes with multiple branches are often used, and the flow maldistribution to the branching channels causes deterioration of thermal and hydraulic performances. A good understanding of flow characteristics involved in those channels is required to improve the phase distribution. The two-phase flow structure in such small multiple-pass channels is, however, so complex that only few studies have been hitherto reported on the two-phase flow distributions in such geometries. In this study, experiments have been conducted on the gas-liquid (nitrogen-water) isothermal flow distribution in horizontal multiple-pass flat channels with a relatively narrow channel clearance. Figure A-1 shows an example of the test channel used in this study. The main and branching channels have flat rectangular cross-sections. The width of the main channel is 10 mm, and that of the branches is 6 mm. The channel clearances (height) of the main and branching channels are the same; three kinds of clearances, 0.5 mm, 1.2 mm, and 2.0 mm, have been tested. The first branch is adjoined to the main channel to form a T-junction at a location 214mm downstream from the gas-liquid mixing section of the main channel, and totally 3-5 branches are connected at 30 mm intervals. Measurements include the observation of the flow pattern, distribution ratios of gas and liquid to each branch, and local void fractions in the main and branching channels. Figure A-2 shows examples of the liquid distribution ratios (left figure) and gas distribution ratios (right one) in each branch (B1∿B5) obtained for different channel clearance C. It has been found that, in all the channels with different clearances, the liquid distribution ratio is the maximum in the branch located furthest downstream (B5 in the figure), but the maximum difference of this ratio among all branches becomes smaller as the channel clearance is decreased. As to the gas distribution ratio, on the other hand, the maximum fraction is attained in the branch located in the middle and the minimum in the last branch irrespective of the channel clearance. It has been found that the local void fraction in a branch can be well correlated to that in the main channel obtained just before each T-junction.[figure]

• 社団法人日本機械学会の論文

著者

• Hirota Masafumi

  Dept. Of Mechanical Engineering Nagoya University

• NAKAYAMA Hiroshi

  Dept. of Mechanical Engineering, Nagoya University

• FUJITA Hideomi

  Dept. of Mechanical Engineering, Meijo University

• MATSUI Hajime

  Dept. of Mechanical Engineering, Nagoya University

• NAKATANI Yuko

  Canon Inc.

• MATSUOKA Katsuya

  Toyota Motor Co.

• Hirota Masafumi

  Dept. Of Mech. Eng. Mie University

• Fujita Hideomi

  Dept. Of Mechanical Engineering Meijo University

• Matsui Hajime

  Dept. Electronics And Information Science Toyota Technological Institute

• Matsui Hajime

  Dept. Of Mechanical Engineering Nagoya University

• Nakayama Hiroshi

  Dept. Of Mechanical Engineering Nagoya University

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