放射冷却の可能性（その２） ― 2019年08月07日
以前、このブログで電力等を消費しない冷却法として放射冷却利用の可能性について書いた（放射冷却の可能性19年5月26日）。これと似た概念を具体化した技術が19年8月5日のNatureの論文に掲載された。A polydimethylsiloxane-coated metal structure for all-day radiative coolingというニューヨーク州立大の論文である。以下そのAbstractを紹介する。
Radiative cooling is a passive cooling strategy with zero consumption of electricity that can be used to radiate heat from buildings to reduce air-conditioning requirements. Although this technology can work well during optimal atmospheric conditions at night, it is essential to achieve efficient cooling during the daytime when peak cooling demand actually occurs. Here we report an inexpensive planar polydimethylsiloxane (PDMS)/metal thermal emitter thin film structure, which was fabricated using a fast solution coating process that is scalable for large-area manufacturing. By performing tests under different environmental conditions, temperature reductions of 9.5 °C and 11.0 °C were demonstrated in the laboratory and an outside environment, respectively, with an average cooling power of ~120 W m–2 for the thin film thermal emitter. In addition, a spectral-selective structure was designed and implemented to suppress the solar input and control the divergence of the thermal emission beam. This enhanced the directionality of the thermal emissions, so the emitter’s cooling performance was less dependent on the surrounding environment. Outside experiments were performed in Buffalo, New York, realizing continuous all-day cooling of ~2–9 °C on a typical clear sunny day at Northern United States latitudes. This practical strategy that cools without electricity input could have a significant impact on global energy consumption.
金属箔にpolydimethylsiloxane (PDMS)という材料をコーティングすることで内部の熱を外部に放射する熱放射板を形成することが可能になるとのこと。テストでは9.5～11℃の温度低下が得られた。
Radiative cooling is a passive cooling strategy with zero consumption of electricity that can be used to radiate heat from buildings to reduce air-conditioning requirements. Although this technology can work well during optimal atmospheric conditions at night, it is essential to achieve efficient cooling during the daytime when peak cooling demand actually occurs. Here we report an inexpensive planar polydimethylsiloxane (PDMS)/metal thermal emitter thin film structure, which was fabricated using a fast solution coating process that is scalable for large-area manufacturing. By performing tests under different environmental conditions, temperature reductions of 9.5 °C and 11.0 °C were demonstrated in the laboratory and an outside environment, respectively, with an average cooling power of ~120 W m–2 for the thin film thermal emitter. In addition, a spectral-selective structure was designed and implemented to suppress the solar input and control the divergence of the thermal emission beam. This enhanced the directionality of the thermal emissions, so the emitter’s cooling performance was less dependent on the surrounding environment. Outside experiments were performed in Buffalo, New York, realizing continuous all-day cooling of ~2–9 °C on a typical clear sunny day at Northern United States latitudes. This practical strategy that cools without electricity input could have a significant impact on global energy consumption.
金属箔にpolydimethylsiloxane (PDMS)という材料をコーティングすることで内部の熱を外部に放射する熱放射板を形成することが可能になるとのこと。テストでは9.5～11℃の温度低下が得られた。
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