Learning from the Growth Process of Natural Ice ~Examination of Ice Making Technique for Single Crystal Ice Using Radiation Cooling~

2022 Fiscal Year Final Research Report

• Project/Area Number: 21K14091
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 19020:Thermal engineering-related
• Research Institution: Nagaoka University of Technology
• Principal Investigator: SUGIHARA Yukinobu 長岡技術科学大学, 工学研究科, 助教 (00824335)
• Project Period (FY): 2021-04-01 – 2023-03-31
• Keywords: 放射冷却 / 製氷技術 / 高電圧パルス印加 / 過冷却

Outline of Final Research Achievements

This study attempted to construct a radiation cooling system that reproduced the growth process of natural ice, and to develop a technology for the stable production of bubble-free single-crystal ice. In particular, the suppression of microbubble swarms that occur in the early stages of ice production was tackled. The effect of supercooling elimination by the application of high-voltage pulses on the deposition of microbubble swarms was investigated. The results showed that an applied voltage of 6000 V or higher was sufficient to promote the resolution of undercooling in the range of the present experimental conditions; when 9000 V was applied, the undercooling was resolved stably within 2 °C of the degree of undercooling and a small initial crystal growth rate was achieved. In other words, the application of a high voltage pulse of 9000 V was effective in suppressing the precipitation of microbubble groups in the early stages of ice making.

Free Research Field

雪氷工学

Academic Significance and Societal Importance of the Research Achievements

氷の性質に関する基礎研究を進めるためには、実験の標準試料となる直径10 cm以上の無気泡単結晶氷が必要となります。日常的に目にする氷はたくさんの結晶から構成されている多結晶氷と呼ばれるものです。多結晶氷を基礎的な研究に使うと、実験で設定した条件のほかに、多結晶氷の性質そのものが実験結果に影響します。そのため、氷の基礎研究を進めるためには、標準試料を定めることが望ましいです。本研究ではこのような要望に応えるべく、天然氷の成長過程に学んだ放射冷却装置を構築し、それに高電圧パルス印加装置を組み合わせることで、氷の基礎研究に使える無気泡単結晶氷を安定的に製造する技術の開発に挑戦したものです。