Natural convection through openings and its application to cattle building ventilation

Bruce, J. M.

doi:10.1016/0021-8634(78)90046-x

Cited by 68 publications

(22 citation statements)

References 2 publications

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“…In buildings without artificial heating the only source of heat within the building is the animals themselves. Bruce (1978) has described in detail the mathematical principles that govern the natural ventilation of animal buildings in still air conditions. Simplifying his argument we can write '/(Ain)' + '/(Ao,,,)2 = !…”

Section: Natural Ventilation In Boxes and Barnsmentioning

confidence: 99%

“…This is valid for a well-designed individual box but almost impossible to achieve in a large barn containing 20 or more horses. In practice, it is often recommended, arbitrarily, that inlets should have twice the area of outlets (Bruce 1978). In this special case Equation 3 can be simplified t o (4) There is, however, an absolute constraint on the size of the smaller opening (usually the outlet) because however large the other opening…”

Section: Tq2mentioning

confidence: 99%

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Air hygiene in stables 1: Effects of stable design, ventilation and management on the concentration of respirable dust

Webster

Clarke

Madelin

et al. 1987

Equine Veterinary Journal

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Summary The concentration of fungal spores, the main constituents of respirable dust in stables, is determined by rates of release from fodder and bedding and rate of clearance, principally by ventilation. This paper outlines the principles that govern the application of natural ventilation to the control of air hygiene in barns and individual boxes for horses. When release rates are low, ventilation rates over four air changes per hour are satisfactory. Ventilation was satisfactory in individual boxes but usually unsatisfactory in barns and specific recommendations are made for improvement. Preliminary observations in stables with clean, well‐managed bedding revealed only small differences between straw, wood shavings and paper. In these circumstances hay tended to be the major source of respirable spores.

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Section: Natural Ventilation In Boxes and Barnsmentioning

confidence: 99%

Section: Tq2mentioning

confidence: 99%

Air hygiene in stables 1: Effects of stable design, ventilation and management on the concentration of respirable dust

Webster

Clarke

Madelin

et al. 1987

Equine Veterinary Journal

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“…Bruce J.M. [12] presented a generalised neutral height-based theory for natural ventilation through multiple openings in one wall. Axleyand Emmerich [13] proposed a method for assessing the suitability of natural ventilation in buildings.…”

Section: Introductionmentioning

confidence: 99%

The first natural ventilation assessment in building design in Djibouti

Omar¹,

Idriss²,

Dabar³

et al. 2016

JLS

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Abstract:With a sustained period of economic growth, rapidly growing populations and with more diversified economies Africa need sustainable development; hence the greater need for massive investments in energy. Sub-Saharan countries such as Djibouti have the potential and ability to harness their natural ventilation as a passive cooling system for designing new houses. The rapid expansion of the Djibouti city is affecting negatively the environment and the safety and comfort of its inhabitants. Proper atmospheric urban planning and management are key to making cities environmentally friendly and sustainable. Based on energy consumption, climate conditions in Djibouti and numerical analysis using Computational Fluid Dynamics (CFD), it is apparent that the natural ventilation creates a thermally comfortable indoor environment in buildings during the cool season of the year. Measured wind data from two measurement systems are presented and discussed. Statistical analyses, wind rose, Weibull distribution were carried out to understand the natural ventilation characteristic, which is used for evolving the basic criteria for economic viability of building in the semi-arid climate of Djibouti. The study found that it is possible to benefit from natural ventilation in buildings during the cool season of the year.

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“…With a view to optimising the design and handling of natural ventilation systems one must understand both quantitatively and qualitatively how this type of ventilation functions in greenhouses. The main driving forces of ventilation for a greenhouse equipped with both roof and side openings are the result of a combination of pressure differences induced by the following effects (Boulard & Baille, 1995;Kittas et al, 1997): the static wind effect due to the mean component of the wind velocity, which induces pressure differences (side wall effect) between the side and the roof openings (Bruce, 1978) and pressure differences between the windward and the leeward parts of the greenhouse ; the buoyancy forces (also called stack or chimney effect) generating a vertical distribution of pressures between the side and roof openings (Bruce, 1982); and the turbulent effect of the wind, generated by pressure fluctuations of the wind velocity along and across the greenhouse openings (Boulard & Baille, 1995;Boulard et al, 1996). Natural ventilation in greenhouses is the result of combining the airflows generated by the wind effect and by the buoyancy of the air (thermal or chimney effect).…”

Section: Introductionmentioning

confidence: 99%

Determinación de los patrones de flujo de aire en un invernadero multitúnel mediante anemometría sónica

López¹,

Valera²,

Molina-Aiz³

et al. 2012

Span. j. agric. res.

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The present work describes a methodology for studying natural ventilation in Mediterranean greenhouses using sonic anemometry. The experimental work took place in the three-span greenhouse located at the agricultural research farm belonging to the University of Almería. This methodology has allowed us to obtain patterns of natural ventilation of the experimental greenhouse under the most common wind regimes for this region. It has also enabled us to describe how the wind and thermal effects interact in the natural ventilation of the greenhouse, as well as to detect deficiencies in the ventilation of the greenhouse, caused by the barrier effect of the adjacent greenhouse (imply a mean reduction in air velocity close to the greenhouse when facing windward of 98% for u, 63% for u y , and more importantly 88% for u x , the component of air velocity that is perpendicular to the side vent). Their knowledge allows us to improve the current control algorithms that manage the movement of the vents. In this work we make a series of proposals that could substantially improve the natural ventilation of the experimental greenhouse. For instance, install vents equipped with ailerons which guide the air inside, or with vents in which the screen is not placed directly over the side surface of the greenhouse. A different proposal is to prolong the opening of the side vents down to the soil, thus fomenting the entrance of air at crop level.Additional key words: buoyancy; insect-proof screens; natural ventilation; wind effect. ResumenDeterminación de los patrones de flujo de aire en un invernadero multitúnel mediante anemometría sónicaEn este trabajo se ha desarrollado una metodología para estudiar la ventilación natural en invernaderos mediterrá-neos mediante anemometría sónica. Los ensayos se han realizado en un invernadero multitúnel de tres módulos situado en el Campo de Prácticas de la Universidad de Almería. Esta metodología nos ha permitido obtener los patrones de ventilación natural del invernadero experimental para los vientos más comunes de la región. También nos ha permitido describir la interacción entre el efecto eólico y térmico, así como detectar deficiencias en la ventilación natural del invernadero debidas al efecto barrera de otro invernadero adyacente (provocando una reducción media en la velocidad del aire en el exterior de la ventana de barlovento de hasta el 98% para u, 63% para u y y, más importante, 88% para u x , la componente de la velocidad del aire que es perpendicular a la superficie de ventilación lateral). Los conocimientos adquiridos en este trabajo nos permitirán mejorar los algoritmos de control del sistema de ventilación. En este trabajo se realizan una serie de propuestas que podrían mejorar sustancialmente la ventilación natural del invernadero. Por ejemplo, se proponen algunas posibles modificaciones de la configuración de las ventanas laterales, buscando una mayor captación del aire exterior: se podría optar por ventanas dotadas de alerones exteriores que dirijan al aire hacia el inte...

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Natural convection through openings and its application to cattle building ventilation

Cited by 68 publications

References 2 publications

Air hygiene in stables 1: Effects of stable design, ventilation and management on the concentration of respirable dust

Air hygiene in stables 1: Effects of stable design, ventilation and management on the concentration of respirable dust

The first natural ventilation assessment in building design in Djibouti

Determinación de los patrones de flujo de aire en un invernadero multitúnel mediante anemometría sónica

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