A comparison of winter pre-heating requirements for natural displacement and natural mixing ventilation

Woods, Andrew W.; Fitzgerald, Shaun; Livermore, Stephen R.

doi:10.1016/j.enbuild.2009.07.030

Cited by 35 publications

(14 citation statements)

References 6 publications

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“…In addition to the building orientation, research shows that natural ventilation improves thermal comfort in buildings that are located in hot and humid climates [45][46][47][48][49][50]. Natural ventilation can be become an integral part of the building envelope by introducing any one of the following ventilation elements viz., wind scoop, wind tower, chimney, double façade, atrium, ventilation chamber, embedded duct and/or ventilation opening in the facade [51,52].…”

Section: Factors Influencing Thermal Comfort Of Buildingmentioning

confidence: 99%

Role of building material in thermal comfort in tropical climates – A review

Latha

Darshana

Venugopal

2015

Journal of Building Engineering

140

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Section: Factors Influencing Thermal Comfort Of Buildingmentioning

confidence: 99%

Role of building material in thermal comfort in tropical climates – A review

Latha

Darshana

Venugopal

2015

Journal of Building Engineering

140

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“…Much of this work has focused on the dynamics of displacement ventilation in conditions where the flow is controlled by buoyancy forces associated with the temperature differences between the interior and exterior (Linden 1999). However there has been some interest in mixing ventilation owing to the potential energy savings in winter (Woods, Fitzgerald & Livermore 2009;Kuesters & Woods 2010). There have also been some studies of the impact of steady or slowly changing wind in natural ventilation and its interaction with buoyancy forces (Hunt & Linden 2001, 2005Lishman & Woods 2008).…”

Section: Introductionmentioning

confidence: 98%

Natural ventilation driven by periodic gusting of wind

Mott¹,

Woods²

2011

J. Fluid Mech.

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We investigate the mixing of a warm enclosed space by a series of discrete gusts of cold air from a high-level opening. Initially we examine the case of a series of gusts of identical size each modelled as a turbulent buoyant thermal. We develop a model of the filling box-like flow which develops in the space and identify the key parameter in the system as the ratio between the initial gust size and the product of the height of the room and the entrainment coefficient. We find an approximate analytic solution for the evolution of the density profile within the space which is in good agreement with a full numerical solution of the governing equations. We successfully test the predictions of the model with a series of new laboratory experiments. The experiments combined with the model also provide a new independent estimate for the entrainment coefficient of a thermal, = 0.37 ± 0.02, based on the propagation speed of a filling box front. We then examine the mixing produced by a series of thermals of non-identical size which we characterize in terms of a mean size and coefficient of variation. We find that as the coefficient of variation increases, the density profile becomes progressively more stratified owing to the asymmetry of dilution through entrainment of large and small thermals. We discuss the implications of these results for the ventilation of a building subject to gusts of wind.

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“…Despite the benefits of passive ventilation systems providing fresh, clean air whilst reducing energy consumption, there are limitations to the operational window of wind towers [32]. In temperate climates where the uptake of wind towers has been high, the operational window of wind towers is limited by the external climate conditions.…”

Section: Previous Related Workmentioning

confidence: 99%

A novel design of a desiccant rotary wheel for passive ventilation applications

2016

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Rotary desiccant wheels are used to regulate the relative humidity of airstreams. These are commonly integrated into Heating, Ventilation and Air-Conditioning units to reduce the relative humidity of incoming ventilation air. To maximise the surface area, desiccant materials are arranged in a honeycomb matrix structure which results in a high pressure drop across the device requiring fans and blowers to provide adequate ventilation. This restricts the use of rotary desiccant wheels to mechanical ventilation systems. Passive ventilation systems are able to deliver adequate ventilation air but cannot control the humidity of the incoming air. To overcome this, the traditional honeycomb matrix structure of rotary desiccant wheels was redesigned to maintain a pressure drop value below 2Pa, which is required for passive ventilation purposes. In addition to this, the temperature of the regeneration air for desorption was lowered. Radial blades extending out from the centre of a wheel to the circumference were coated in silica gel particles to form a rotary desiccant wheel. Computational Fluid Dynamics (CFD) modelling of the design was validated using experimental data. Reduction in relative humidity up to 55% was seen from the system whilst maintaining a low pressure drop across the new design. As an outcome of the work presented in this paper, a UK patent GB1506768.9 has been accepted.

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A comparison of winter pre-heating requirements for natural displacement and natural mixing ventilation

Cited by 35 publications

References 6 publications

Role of building material in thermal comfort in tropical climates – A review

Role of building material in thermal comfort in tropical climates – A review

Natural ventilation driven by periodic gusting of wind

A novel design of a desiccant rotary wheel for passive ventilation applications

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