Finless heat exchangers for air conditioners using ultra-thin flat multi-port tubes

2016 Fiscal Year Final Research Report

• Project/Area Number: 15K13880
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Thermal engineering
• Research Institution: The University of Tokyo
• Principal Investigator: Eiji Hihara 東京大学, 大学院新領域創成科学研究科, 教授 (00156613)
• Research Collaborator: Saitoh Shizuo 東京大学, 大学院工学系研究科, 助教 (60170502) ; Li Jiyang 東京大学, 大学院新領域創成科学研究科
• Project Period (FY): 2015-04-01 – 2017-03-31
• Keywords: 熱交換器 / 冷凍空調機器

Outline of Final Research Achievements

Heat exchangers for air conditioners are conventionally made of copper tubes with a diameter of 6 to 8 mm crimped with aluminum fins. In order to improve the efficiency and reduce the amount of charged refrigerant, this research aimed to develop an aluminum finless heat exchanger using multi-port flat tubes. Since there is no fin between the tubes, drainage problems of condensed water and defrosted water are solved.
Specifically, the flow pattern and the boiling heat transfer characteristics inside the multi-port flat tubes were experimentally clarified, and a suitable cross-sectional geometry of the tube was examined. A vortex generator for enhancing air-side heat transfer was proposed, and its effectiveness was verified by experiments and CFD. The distribution of gas-liquid two-phase flow in the inlet header was visualized, and an effective header structure was proposed.

Free Research Field

熱工学