CFD and experimental data of closed-loop wind tunnel flow

The data presented in this article were the basis for the study reported in the research articles entitled ‘A validated design methodology for a closed loop subsonic wind tunnel’ [1], which presented a systematic investigation into the design, simulation and analysis of flow parameters in a wind tunnel using Computational Fluid Dynamics (CFD). The authors evaluated the accuracy of replicating the flow characteristics for which the wind tunnel was designed using numerical simulation. Here, we detail the numerical and experimental set-up for the analysis of the closed-loop subsonic wind tunnel with an empty test section

Sustainable buildings: opportunities, challenges, aims and vision

In recent years, a large and rapidly growing body of research in the built environment has involved multi disciplinary collaboration, a trend driven by the increased funding for multi-disciplinary projects and research institutes, along with the challenges and opportunities detailed previously. There is therefore more scope for disseminating the research output of these initiatives in a focused, effective and multi-disciplinary journal. Sustain able Buildings intends to fulfil this role and serve the diverse international community of engineers, architects, urban physicists, urban designers, researchers, scientists and industry professionals, providing a forum where each can communicate their original and innovative findings and provide motivation and direction towards meeting the current and future challenges of sustainable buildings. The journal will focus on advancing the knowledge on the forum of the global sustainability practices and to stimulate the exploration and innovations aimed at creating a climate resilient built environment that reduces energy consumption and environmental deterioration and creates high quality indoor environment

Oxidation of biogenic and water-soluble compounds in aqueous and organic aerosol droplets by ozone: a kinetic and product analysis approach using laser Raman tweezers

The results of an experimental study into the oxidative degradation of proxies for atmospheric aerosol are presented. We demonstrate that the laser Raman tweezers method can be used successfully to obtain uptake coeffcients for gaseous oxidants on individual aqueous and organic droplets, whilst the size and composition of the droplets is simultaneously followed. A laser tweezers system was used to trap individual droplets containing an unsaturated organic compound in either an aqueous or organic ( alkane) solvent. The droplet was exposed to gas- phase ozone and the reaction kinetics and products followed using Raman spectroscopy. The reactions of three different organic compounds with ozone were studied: fumarate anions, benzoate anions and alpha pinene. The fumarate and benzoate anions in aqueous solution were used to represent components of humic- like substances, HULIS; a alpha- pinene in an alkane solvent was studied as a proxy for biogenic aerosol. The kinetic analysis shows that for these systems the diffusive transport and mass accommodation of ozone is relatively fast, and that liquid- phase di. ffusion and reaction are the rate determining steps. Uptake coe. ffcients, g, were found to be ( 1.1 +/- 0.7) x 10(-5), ( 1.5 +/- 0.7) x 10 (-5) and ( 3.0 - 7.5) x 10 (-3) for the reactions of ozone with the fumarate, benzoate and a- pinene containing droplets, respectively. Liquid- phase bimolecular rate coe. cients for reactions of dissolved ozone molecules with fumarate, benzoate and a- pinene were also obtained: k(fumarate) = ( 2.7 +/- 2) x 10 (5), k(benzoate) = ( 3.5 +/- 3) x 10 (5) and k(alpha-pinene) = ( 1-3) x 10(7) dm(3) mol (-1) s (- 1). The droplet size was found to remain stable over the course of the oxidation process for the HULIS- proxies and for the oxidation of a- pinene in pentadecane. The study of the alpha- pinene/ ozone system is the first using organic seed particles to show that the hygroscopicity of the particle does not increase dramatically over the course of the oxidation. No products were detected by Raman spectroscopy for the reaction of benzoate ions with ozone. One product peak, consistent with aqueous carbonate anions, was observed when following the oxidation of fumarate ions by ozone. Product peaks observed in the reaction of ozone with alpha- pinene suggest the formation of new species containing carbonyl groups

Effect of Rotation Speed of a Rotary Wheel on Ventilation Supply Rates of Wind Tower System

This study explores the integration of a rotary thermal wheel into a wind tower system, specifically the effect of the rotation speed on the ventilation rate and heat recovery. Wind towers are capable of supplying recommended levels of supply air under a range of external conditions, integrating a rotary thermal wheel will cause a reduction in the air supply rates due to the blockage created by the wheel. Using Computational Fluid Dynamics (CFD) analysis, the air supply rate and heat transfer of the rotary thermal wheel have been calculated for a range of rotation speeds between 0rpm – 500rpm. The recommended air supply rate of 8l/s/p is attained up to a rotation speed of 50rpm; beyond this rotation speed the air supply rate is too low. The maximum temperature recovered across the rotary thermal wheel is measured as 1.77°C at a rotation speed of 20rpm. Using the two results gained from the analysis, an optimum operating range of the rotary thermal wheel can be determined between 5rpm and 20rpm. The technology presented here is subject to an international patent application (PCT/GB2014/052513)

A CFD analysis of several design parameters of a road pavement solar collector (RPSC) for urban application

Previous investigations of the Urban Heat Island (UHI) effects have highlighted the long-term negative impacts of urban street canyons on surroundings temperatures that indirectly contribute to global warming. Studies on road pavement solar collector (RPSC) system have shown the potential of reducing the heat from the pavement surface by absorbing the heat from the pavement and harnessing the thermal energy. This study expands the investigation of optimising the RPSC system based on four tested parameters (pipe diameter, pipe depth, water velocity and water temperature) comparing the system performance in terms of Delta T of inlet-outlet, potential thermal collection (PTC) and surface temperature reduction (STR). Two types of external environmental conditions were considered: (i) urban domain resembling a street canyon (ii) flat surface resembling a low density or rural area. ‘De-coupled’ CFD method was employed based on previously author’s published work by simulating the effect of external environment (macro domain) onto RPSC system (micro domain) in two separate CFD modelling. Initially, both domains were validated with numerical and experimental data from previously published works. In comparing the RPSC application in urban domain and flat/rural domain; it was found that the system adjustment based on high and low conditions of water velocity provided the best performance improvement with average 28% higher in terms of PTC and STR as compared to other simulated parameters. Yet, insignificant Delta T (less than 5 K) was obtained with values over 0.02 m in the pipe diameter and in the 0.25 m/s water velocity

CFD and Wind Tunnel Study of the Performance of a Multi-Directional Wind Tower with Heat Transfer Devices

The aim of this work was to investigate the performance of a multi-directional wind tower integrated with heat transfer devices (HTD) using Computational Fluid Dynamics (CFD) and wind tunnel analysis. An experimental scale model was created using 3D printing. The scale model was tested in a closed-loop wind tunnel to validate the CFD data. Numerical results of the supply airflow were compared with experimental data. Good agreement was observed between both methods of analysis. Smoke visualisation test was conducted to analyse the air flow pattern in the test room attached underneath it. Results have indicated that the achieved indoor air speed was reduced by up to 17% following the integration of the cylindrical HTD. The effect of varying the number of HTD on the system's thermal performance were investigated. The work highlighted the potential of integrating HTD into wind towers in reducing the air temperature. The technology presented here is subject to a UK patent application (PCT/GB2014/052263)

Data on the natural ventilation performance of windcatcher with anti-short-circuit device (ASCD)

This article presents the datasets which were the results of the study explained in the research paper ‘Anti-short-circuit device: a new solution for short-circuiting in windcatcher and improvement of natural ventilation performance’ [1] which introduces a new technique to reduce or prevent short-circuiting in a two-sided windcatcher and also lowers the indoor CO2 concentration and improve the ventilation distribution. Here, we provide details of the numerical modelling set-up and data collection method to facilitate reproducibility. The datasets includes indoor airflow, ventilation rates and CO2 concentration data at several points in the flow field. The CAD geometry of the windcatcher models are also included

Energy efficiency and comfort in the workplace: Norwegian cellular and British open plan workplaces

Two office layouts with high and low levels of thermal control were compared, respectively Norwegian cellular and British open plan offices. The Norwegian practice provided every user with control over a window, blinds, door, and the ability to adjust heating and cooling. Occupants were expected to control their thermal environment to find their own comfort, while air conditioning was operating in the background to ensure the indoor air quality. In contrast, in the British office, limited thermal control was provided through openable windows and blinds only for occupants seated around the perimeter of the building. Centrally operated displacement ventilation was the main thermal control system. Users’ perception of thermal environment was recorded through survey questionnaires, empirical building performance through environmental measurements and thermal control through semi-structured interviews. The Norwegian office had 35% higher user satisfaction and 20% higher user comfort compared to the British open plan office. However, the energy consumption in the British practice was within the benchmark and much lower than the Norwegian office. Overall, a balance between thermal comfort and energy efficiency is required, as either extreme poses difficulties for the other

Application of a Passive Cooling Wind Catcher within the Built Environment: Numerical and Experimental Analysis

Commercial wind catchers are passive ventilation devices adapted from vernacular architecture of Middle Eastern cultures which date back hundreds of years. The wind catcher sustain natural ventilation and cooling in buildings through wind driven airflow as well as temperature difference. However, its cooling performance is limited in hot climates, especially during the summer period. In this study, a standard roof-mounted wind catcher was integrated with heat pipes to reduce the temperature of the supply airflow. A commercial CFD code was used to simulate the effect of the heat pipes on the ventilation and thermal performance of the system. A 1:10 scale model was created using a 3D printer and tested inside a low-speed wind tunnel. Qualitative and quantitative wind tunnel analysis of the airflow through the wind catcher were compared with the CFD results. Field testing of the wind catcher was also conducted in the Middle East to evaluate its performance under real conditions. A cooling potential of up to 12K was identified in this study. The technology presented here is subject to an international patent application (PCT/GB2014/052263)

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

Windcatcher is an effective technique for naturally ventilating a space and improving indoor air quality. A common problem for modern and traditional windcatchers is air short-circuiting. Air-short-circuiting in windcatchers occurs when the air entering through the supply channel immediately exits through the exhaust channel without circulating and mixing inside the enclosed space. Several previous works on windcatchers have observed the “short-circuiting” effect and concluded that it has a negative impact on the ventilation performance however, no work have provided a solution to eliminate this effect. The present study will address this issue by incorporating a component called the anti-short-circuiting device (ASCD) and investigating its potential to eliminate air short-circuiting in windcatchers and improve ventilation performance. Two methods were employed in this research: experimental and Computational Fluid Dynamics (CFD) study. For the experimental work, three scaled models were studied in a wind tunnel. The CFD modelling was validated using the air velocity measurements and good correlation was observed with average error below 10%. The results showed that the ASCD windcatcher with angles between 20° and 80° prevented air-short-circuiting while supplying up to 40–51 l/s per occupant, which is higher than the minimum recommendations of ASHRAE62.2 and BS5925. In addition, the windcatcher without ASCD showed 8% higher CO2 concentration in the room, indicating that the ASCD windcatcher was more effective in removing stale air out of the room. Furthermore, the average air velocity in the room at sitting height with the ASCD windcatcher was 19–28% higher than windcatcher without ASCD