流れるように安定した(Steady as it goes and flows)

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2022-08-01 オークリッジ国立研究所(ORNL)

Oak Ridge National Laboratory researchers developed a device called a piezoelectric-driven magnetic actuator, or PEDMA, that can be inserted into the header of a microchannel heat exchanger to keep refrigerants flowing evenly and the HVAC unit running efficiently. Credit: ORNL, U.S. Dept. of Energy

研究者は、圧電駆動磁気アクチュエータ(PEDMA)と呼ばれるデバイスを挿入することで、暖房・換気・空調装置のマイクロチャネル熱交換器が冷媒を均一かつ継続的に分配し続けることができることを実証しました。
研究チームは、3Dプリントした樹脂部品と小型の永久磁石からなるPEDMAインサートのプロトタイプを開発しました。

<関連情報>

マイクロチャネル熱交換器の偏在を解消する磁気結合型圧電アクチュエータの実験結果 Experimental results of a magnetically coupled piezoelectric actuator to relieve microchannel heat exchanger maldistribution

Joseph Rendall,TugbaTurnaoglu,Viral K.Patel
International Communications in Heat and Mass Transfer  Available online: 24 February 2022
DOI:https://doi.org/10.1016/j.icheatmasstransfer.2022.105944

Highlights

•Maldistribution in microchannel evaporators degrades performance.
•Active control of refrigerant maldistribution can increase lost performance.
•Experimental evaluation of prototypes of active systems shows significant impact.
•Maldistribution was controlled by magnetically coupled piezoelectric actuators.

Abstract

Refrigerant maldistribution is a common issue in microchannel heat exchangers. Refrigerant maldistribution can have significant negative effects on the heat transfer performance and increase the pressure drop, leading to increased superheat temperature at the outlet and increased compressor work, lowering system efficiency. A novel piezoelectric-driven magnetic actuator (PEDMA) was fabricated and inserted into the inlet header of the microchannel evaporator, with the goal of improving the non-uniformity of the flow distribution by regulating the flow in the header to the microchannels. Two prototype PEDMA designs were tested and showed significant impact on the refrigerant flow in the region of actuation. In the first design, the experimental data showed superheat reductions up to 9 °C when the individual channel temperatures were measured. The second design redistributed the refrigerant such that a 1% increase in capacity was calculated for the whole heat exchanger without significantly impacting the heating efficiency. The experimental results demonstrate the successful operation of the PEDMA devices and represent a new method of active flow distribution control which is based on a simple design with minimal additional energy consumption, and which can be inserted into microchannel heat exchanger headers to potentially relieve the refrigerant maldistribution.

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