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Updated: Jun 20, 2025
08:25
Measurements of Local Instantaneous Convective Heat Transfer in a Pipe - Single and Two-phase Flow
Published on: April 30, 2018
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Experimental study of the two-phase flow distribution in helical-structured vertical headers.
Moojoong Kim1, Jongsoo Jeong2, Kiyoshi Saito2
1Research Institute for Science and Engineering, Waseda University, Shinjuku-ku, Tokyo, 169-8555, Japan.
Heliyon
|July 18, 2024
Summary
A novel helical structure in vertical headers significantly improves refrigerant distribution in microchannel heat exchangers. This enhancement is crucial for optimizing the performance of air conditioning systems by ensuring even two-phase flow.
Area of Science:
- Thermodynamics and Heat Transfer
- Fluid Dynamics in Microchannels
- Refrigeration and Air Conditioning Systems
Background:
- Vertical headers are critical for distributing two-phase refrigerants in microchannel heat exchangers.
- Optimal performance relies on even refrigerant distribution, which is influenced by header geometry and flow rate.
- Existing designs face challenges in achieving uniform distribution, impacting overall system efficiency.
Purpose of the Study:
- To investigate the impact of a helical structure within a vertical header on two-phase flow distribution.
- To compare the distribution performance of a helical header against a conventional straight vertical header.
- To evaluate the influence of varying mass flow rates and vapor qualities on flow characteristics.
Main Methods:
- An experimental setup simulating a microchannel heat exchanger was utilized.
- Distribution characteristics were measured for a helical vertical header under varied inlet conditions (mass flow rate: 50-100 kg/h; vapor quality: 0.1-0.2).
- Performance was benchmarked against a straight vertical header with identical cross-sectional properties.
Main Results:
- The helical structure promoted a distinct flow pattern, enhancing the mixing of the two refrigerant phases.
- Reduced inertial forces were observed in the helical header compared to the straight header.
- The helical design demonstrated superior refrigerant distribution performance.
Conclusions:
- Implementing a helical structure in vertical headers significantly improves two-phase flow distribution in microchannel heat exchangers.
- This structural modification leads to better refrigerant distribution, crucial for optimizing heat exchanger performance.
- The helical header offers a promising solution for enhancing the efficiency of refrigeration and air conditioning systems.
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