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English to Indonesian: Passive Cooling: Radiation General field: Tech/Engineering Detailed field: Architecture
Source text - English Radiative cooling is the transfer of heat from a warmer surface to a cooler surrounding surface (or outer space). It may be used to cool the building (where warm building surfaces radiate heat to the sky) or to cool people (where the warm skin radiates heat to cooler surrounding room surfaces – to the cool walls of an underground building, for example). In general, the drier the atmosphere, the more readily terrestrial surfaces can radiate heat to outer space. If there were no atmosphere at all, then radiative loss to outer space would be extremely rapid. This “nocturnal radiation” effect can be costly to agriculture, causing frost at above-freezing air temperatures. Some fruit corps are sensitive to freezing and are protected from early morning frosts by the use of smudge pots and wind generators.
Radiative cooling was used to produce ice in hot-arid regions of ancient Iran. While the process was not used for summer comfort conditioning, it clearly demonstrates the potential of radiative cooling. The winter nighttime temperature often dropped within a few degrees of freezing. Enclosed patios and courtyards benefit from radiative cooling. This loss of night radiative cooling is typically more than counter balanced by protective daytime shading and the increased evaporation and transpiration. The roof can be designed to enhance this courtyard cooling cycle. If the roof surrounding the courtyard is sloped toward the courtyard, as the roof cools by radiation at night, the layer of air above the roof is also cooled. Reynolds et al. (1982) studied traditional courtyards in Colima, Mexico, and concluded that the subjective perception of coolness in these enclosures exceeded the measurable effects.
Harold Hay (1970) invented a roof-pond system that provided both passive summer cooling as well as winter passive solar heating. His invention was demonstrated by some early proof-of-concept experiments whereby a foam box was filled with water and the lid removed to receive insolation during the day and replaced at night to reduce heat loss. The measured increase in the water temperature demonstrated the passive solar heating potential of the system. Then by simply reversing the positions of the insulating lid (on during the day to prevent solar heat gain, off at night to allow cooling by radiation and evaporation), radiative cooling was effected.
The patented Skytherm system has subsequently been tested in a full-scale test room and occupied house. In operation, during summer day, the water absorbs heat through the metal roof/ceiling from the room below and is protected from solar heat gain by the insulating panels. At night, the panels are removed, allowing the water bags to radiate heat to the night sky. The system is most effective in mild climates which have both heating and cooling requirements. In colder climates, the horizontal slope is very inefficient collector orientation. Also, the presence of snow and ice may interfere with the operation of the insulting shutters that are essential to the system’s performance.
The cool pool is an innovative passive roof-cooling system. It consists of an open roof pond shaded from summer sun by sloping louvers which still allow exposure of the pond to the north sky. Cool pool tubes could be designed to function as a water wall for winter passive heating by locating them behind south glazing and blocking circulation to the roof pond. Horizontal surfaces are the most efficient radiative cooling surfaces because they are most directly exposed to the sky: tilted cooling surfaces are exposed to warmer terrestrial surfaces below the horizon, and thus experience a higher effective sky temperature. There should be a maximum thermal coupling between the conditioned space and the radiating surface: the area should be as large as practical and the thermal resistance should be minimized, allowing the heat to be readily transferred from the room to the roof. The warmer the roof, the greater the difference between the roof and sky temperatures and the greater the cooling effect. Because sky temperatures are typically below ambient air temperatures surrounding the building, any airflow across the radiative cooling surface heats it by convection. Therefore, any strategy that reduces airflow across the collector will enhance the cooling process.
Translation - Indonesian Pendinginan radiatif adalah perpindahan panas dari permukaan yang lebih hangat ke permukaan dingin di sekitarnya (atau luar angkasa). Pendinginan radiatif juga dapat digunakan untuk mendinginkan bangunan (di mana bangunan permukaan hangat memancarkan panas ke langit) atau orang-orang kedinginan (di mana kulit hangat memancarkan panas ke dingin permukaan kamar sekitarnya - dengan dinding dingin sebuah bangunan bawah tanah, misalnya). Secara umum, semakin kering atmosfer, semakin mudah permukaan bumi dapat memancarkan panas ke angkasa luar. Jika tidak ada atmosfer sama sekali, maka kerugian radiasi ke luar angkasa akan sangat cepat. Efek "radiasi nokturnal" ini dapat menjadi mahal untuk pertanian, menyebabkan kebekuan di atas titik beku suhu udara. Beberapa bibit buah sensitif terhadap pembekuan dan dilindungi dari salju pagi dengan menggunakan pot noda dan generator angin.
Pendinginan radiasi digunakan untuk memproduksi es di daerah panas-kering Iran kuno. Sementara proses itu tidak digunakan untuk pengkondisian kenyamanan pada musim panas, proses itu jelas menunjukkan potensi pendinginan radiasi. Suhu musim dingin malam hari seringkali menurun dalam beberapa derajat pembekuan. Teras tertutup dan halaman mendapat manfaat dari pendinginan radiasi. Kehilangan pendinginan radiatif pada malam hari tersebut biasanya lebih dari penyeimbang dengan perlindungan siang hari dan evaporasi dan transpirasi yang meningkat. Atap dapat dirancang untuk meningkatkan siklus pendinginan halaman. Jika atap sekitarnya halaman melengkung menuju halaman, seperti atap dingin oleh radiasi di malam hari, lapisan udara di atas atap juga didinginkan. Reynolds et al. (1982) mempelajari halaman tradisional di Colima, Meksiko, dan menyimpulkan bahwa persepsi subjektif dari kesejukan dalam kandang melebihi efek terukur.
Harold Hay (1970) menemukan sistem roof-pond yang disediakan baik pendinginan musim panas pasif serta pemanas musim dingin surya pasif. Penemuannya ditunjukkan oleh beberapa bukti konsep percobaan awal dimana kotak busa diisi dengan air dan penutup dihapus untuk menerima insolasi siang hari dan diganti pada malam hari untuk mengurangi kehilangan panas. Peningkatan diukur dalam suhu air menunjukkan potensi pemanasan pasif surya dari sistem. Kemudian hanya dengan membalikkan posisi tutup isolasi (pada siang hari untuk mencegah mendapatkan panas matahari, dimatikan di malam hari untuk memungkinkan pendinginan oleh radiasi dan penguapan), pendinginan radiasi telah dilakukan.
Sistem Skytherm dipatenkan kemudian telah diuji dalam ruang tes skala penuh dan rumah yang didiami. Dalam operasi, siang hari musim panas, air menyerap panas melalui atap metal / langit-langit dari ruang bawah dan dilindungi dari mendapatkan panas matahari oleh panel isolasi.Pada malam hari, panel akan dihapus, memungkinkan kantong air untuk memancarkan panas ke langit malam. Sistem ini paling efektif di iklim ringan yang memiliki kebutuhan pemanasan dan pendinginan. Dalam iklim dingin, kemiringan horizontal adalah orientasi kolektor sangat tidak efisien.Juga, kehadiran salju dan es dapat mengganggu pengoperasian jendela yang penting untuk kinerja sistem.
The cool pool adalah sebuah sistem pendinginan atap pasif yang inovatif Cool-pool ini terdiri dari sebuah kolam atap terbuka berbayang dari matahari musim panas dengan kisi-kisi miring yang masih memungkinkan paparan dari kolam ke langit utara. Tabung cool pool dapat dirancang untuk berfungsi sebagai dinding air untuk pemanasan musim dingin pasif dengan menempatkan mereka di belakang kaca selatan dan memblokir sirkulasi ke kolam atap. Permukaan horizontal adalah permukaan pendinginan radiasi yang paling efektif karena mereka yang paling langsung terkena langit: permukaan pendingin miring yang terkena permukaan bumi lebih hangat di bawah cakrawala, dan dengan demikian mengalami suhu langit tinggi yang efektif. Harus ada pasangan termal maksimum antara ruang AC dan permukaan memancar: daerah harus sama besar dengan praktis dan tahan panas harus diminimalkan, sehingga panas akan mudah dipindahkan dari ruangan ke atap. Semakin hangat atap, semakin besar perbedaan antara atap dan suhu langit dan efek pendinginan semakin besar. Karena suhu langit biasanya di bawah suhu udara ambien di sekitar gedung, setiap aliran udara di permukaan pendinginan radiasi memanaskan dengan konveksi. Oleh karena itu, setiap strategi yang mengurangi aliran udara di seluruh kolektor akan meningkatkan proses pendinginan.
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Years of experience: 1. Registered at ProZ.com: Jan 2013.
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