Multiple steady states in stack ventilation

Chenvidyakarn, Torwong; Woods, Andrew W.

doi:10.1016/j.buildenv.2004.06.020

Cited by 44 publications

(17 citation statements)

References 1 publication

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“…This may be understood by considering the limiting case in which the low-level vents are all closed: the mixing ventilation flow regime through the roof becomes established, with the net circulation, in order that the mall can ventilate. 3 As the lowlevel vents are gradually opened, this mixing ventilation flow The net circulation pattern may be seen in the photograph by the inclined streaks of dye within the fluid. This blue zone corresponds to the layer of cool air in the mall associated with the supply of air from the mechanical cooling system and the natural ventilation flow persists until the low-level vents provide sufficient inflow area that a pure upward displacement ventilation regime is able to reverse the flow in the upper stacks.…”

Section: Upward Displacement Ventilationmentioning

confidence: 99%

Energy efficiency with natural ventilation: a case study

Fitzgerald¹,

Woods²

2007

Proceedings of the Institution of Civil Engineers - Energy

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Application of laboratory analogue modelling of air flow in a naturally ventilated shopping mall is reviewed in this paper. A detailed study of the ventilation was undertaken to establish the principles and to explore how natural ventilation might interact with a localised mechanical ventilation system designed to enhance the cooling of a high density food court area. The case study is used to show how the combination of laboratory modelling and simplified mathematical modelling enables one to rapidly identify the various flow regimes which can occur, to quantify the resultant flows and mean temperatures and to thereby develop appropriate ventilation strategies for the different external conditions which occur through the year. INTRODUCTION 1.Energy use in buildingsThe UK domestic energy gap is widening and national demand is set to outstrip indigenous supply. Crucially, there are major opportunities to close the gap by reducing the UK energy demand. The provision of energy to buildings accounts for 40% of all energy consumed and much of this is associated with heating and cooling. It is well known that energy inefficiency is wide-ranging in current UK building stock. Older buildings are typically less well insulated than newer structures, and have inefficient energy management systems and inefficient lighting. Improving the energy efficiency of existing buildings is important, but can be challenging owing to the limited budgets often allowed for refurbishment. However, even in new buildings that are intended to be low energy, there are considerable variations in energy efficiency. For example, air-conditioned buildings, which are increasingly becoming the norm, typically cost more and may consume tens of per cent more energy than those without airconditioning. Properly designed non-air-conditioned buildings therefore provide a significant opportunity for minimising fuel consumption within the building sector. One of the key challenges for engineers is to design low-energy building systems that provide comfortable conditions by responding effectively to changes in external conditions (such as wind and temperature) and internal heat loads.

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Section: Upward Displacement Ventilationmentioning

confidence: 99%

Energy efficiency with natural ventilation: a case study

Fitzgerald¹,

Woods²

2007

Proceedings of the Institution of Civil Engineers - Energy

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“…Typically an adjustment time of 3:5t s is sufficient for the room to reach steady state [11]. By applying the appropriate values of geometry from the apparatus and using for example a 1 ¼ a 3 ¼ 3:5 cm 2 and Q 1 ¼ 250 W we obtain a convergence time of approximately 50 min for the lab scale experiments.…”

Section: Appendixmentioning

confidence: 99%

“…Following Chenvidyakarn and Woods [11], a dimensional timescale to converge to equilibrium, t s , may be given by…”

Section: Appendixmentioning

confidence: 99%

Natural ventilation of a building with heating at multiple levels

Livermore

Woods

2007

Building and Environment

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“…In order to test the model, an analogue experiment has been developed similar to that employed by Chenvidyakarn and Woods [6]. The apparatus has two floors connected to a series of stacks.…”

Section: Apparatusmentioning

confidence: 99%

“…As well as ventilating lower level floors of minimal heat load, the scheme could also be used to enhance night or evening cooling of thermal mass in an undercroft, in for example, theatres. In this work, attention is restricted to the case of upward displacement ventilation, although it is noted that where multiple stacks are employed it is possible for some of the stacks to witness downward flow [6].…”

Section: Introductionmentioning

confidence: 99%