A numerical investigation into the effect of windvent dampers on operating conditions

Abstract

a b s t r a c tThe United Kingdom has made a commitment to reduce buildings carbon emissions, placing a greater onus on sustainable energy sources. Therefore, an anticipated increase of usage of zero carbon technologies in new and existing building has led to the emergence of passive ventilation devices as an alternative to mechanical ventilation and air conditioning. The windvent is a commercially available passive ventilation device. The device is constructed from sheet metal and works on the principle of pressure differential. Whereby air rises, creating a low pressure in the receiving room, which then draws in the fresh air. The ensuing air delivery velocity is controlled by the dampers, installed at the room entry interface. The dampers are actuator operated, and form the basis of the control system for the device. The purpose of this paper is to investigate the control mechanism for the device and ascertain an optimum operating range. Numerical analysis is carried out using a commercial computational fluid dynamics (CFD) code, to investigate the effect of various damper angles (range 0-901). The results show that optimum operating occurs at a damper angle range of 45-551, at the UK average 4.5 m/s external wind speed. The operating range when considered in tandem with macro climatic influences is central to determining the overall control strategy for the fresh air supply. The results provide useful information for both engineers and architects when examining ways to reduce new and existing buildings running costs, and conform to new legislation.

Anti-short-circuit device: A new solution for short-circuiting in windcatcher and improvement of natural ventilation performance

“…In addition to improving human comfort, they have low maintenance cost due to having no moving parts, capturing and supplying clean and fresh air at roof level compared to low level windows [13]. Although it has many advantages, a problem of both modern and traditional multi-channel windcatchers is air-short-circuiting that is reported by different scholars in previous studies [14][15][16][17][18][19] and has a negative impact on the ventilation performance of windcatcher. Air-short-circuiting occurs when the air entering through the supply channel immediately exits through the exhaust without circulating inside the enclosed space (see Fig.…”

“…The spacing of the occupants was based on reference [19]. model on natural ventilation studies was also found in previous works of [16] and [18] to be reliable and accurate. The governing equations for k-turbulence were not included here but can be found in the ANSYS 14.5 Fluent theory guide [36].…”

“…The average of difference between experimental data and mentioned model was 9.3% (lower than the other two models). Therefore, standard k-model was selected for current numerical study which was in agreement with pervious windcatcher studies in reference of [16] and [18]. 3 Results and discussion…”

“…Hughes & Ghani [16] carried out the CFD modelling of a four-sided windcatcher to analyze the effect of the control mechanism of air flow inside the system. In the CFD study, nineteen numerical models were created in different damper angles range of 0-90° with an interval of 5°.…”

Evaluation of a two-sided windcatcher integrated with wing wall (as a new design) and comparison with a conventional windcatcher

“…The average of difference between experimental data and mentioned model was 11% (lower than the other two models). Therefore, standard k-model was selected for current numerical study which was in agreement with pervious windcatcherstudies in reference of [34] and [35]. …”