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E-book Attachment Ventilation Theory

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Penilaian

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Air distribution affects air quality, thermal environment, and work efficiency. The goal of ventilation is to provide occupants with clean air for breathing and thermal comfort. In essence, ventilation means controlling air movement in rooms or built environments. It is the science of studying the interaction of natural convection and organized currents of ventilation air. Ventilation affects not only indoor air quality and thermal comfort, but also energy consumption over the building’s life. The air distribution is a result of the complex interaction of different flows. Therefore, room air distribution in space and in time domains should be carefully considered in order to avoid regions of high velocity and low temperature as well as regions of polluted air, which may affect occupants’ comfort and well-being. This book introduces the principle and methods of applying fluid mechanics to predict the air movement along various wall surfaces in a ventilated room. Attachment ventilation (attached ventilation) theory and design methods are put forward. The air currents induced by production processes or heated objects are diverse in any room, industrial workshop, or any given space. The purpose of ventilation is to meet the required air parameters (such as temperature t, velocity u, and rela-tive humidity RH, etc.) in a given space and guarantee the environmental condition of people’s lives or industrial production. It is essential to control those natural air currents by jets of air supplied, as a result of interaction, eventually achieving specified parameters of the built environment. The ventilation task is to regulate the air change in a confined enclosure to create the intended temperature, velocity, concentration field, etc. For mechanical ventila-tion, the air is supplied to given spaces in the form of jets by air diffusers or openings of the air passage. The ventilation jets can dilute or blow thermal air (excessive heat and moisture) or hazardous pollutants to a specific area and then remove them in an ordered manner. A wide variety of definitions exist in literature for air distribution. ASHRAE defines air distribution as “room air distribution systems are intended to provide thermal comfort and ventilation for space occupants and processes” (ASHRAE 2017). In a broad sense, air distribution is a rationalized and organized air flow process in any given space to meet the requirements of air temperature, velocity, humidity, airflow rate, and human comfort (CIBSE 2016). The “given spaces” comprise ordi-nary industrial and civil buildings, enclosed and semi-enclosed zones involved in aeronautic and astronautic, transportation, facility agriculture environment, etc. Up to date, there have mainly been traditionally two kinds of ventilation modes, mixing and displacement ventilation, since the invention of central air-conditioning systems. The former is based on the dilution principle, supplying a high momentum flow from the ceiling or upper sidewall to the room, while the latter is based on the displacement principle, supplying a low momentum flow from the floor or lower wall area into the occupied zone. This chapter briefly presents their pros and cons. Following this, a novel ventilation mode has been proposed, i.e., vertical wall attach-ment (VWAV) and column attachment ventilation (CAV). The ventilation evaluation indexes are prsented, such as vertical temperature gradient, effective draft tempera-ture, air diffusion performance index, ventilation efficiency, and thermal stratification height.

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Ketersediaan

Informasi Detail

Judul Seri

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No. Panggil

624 ANG a

Penerbit

Singapore : Springer Nature., 2023

Deskripsi Fisik

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Bahasa

English

ISBN/ISSN

9789811992599

Klasifikasi

624

Tipe Isi

text

Tipe Media

computer

Tipe Pembawa

online resource

Edisi

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Subjek

Civil Engineering

Info Detail Spesifik

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Pernyataan Tanggungjawab

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Versi lain/terkait

Lampiran Berkas

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