183 research outputs found
Performance of building integrated photovoltaic facades: Impact of exterior convective heat transfer
No full textsponsorship: Twan van Hooff is currently a postdoctoral fellow of the Research Foundation -Flanders (FWO), Belgium and acknowledges its financial support (project FWO 12R9718N). (FWO 12R9718N)status: Publishe
Understanding the behaviour of naturally-ventilated BIPV modules: A sensitivity analysis
No full textsponsorship: Twan van Hooff is currently a postdoctoral fellow of the Research Foundation Flanders (FWO) and acknowledges its financial support (project FWO 12R9718N). (project FWO|12R9718N)status: Publishe
Minimum momentum flux ratio required to prevent air curtain breakthrough in case of cross-curtain pressure gradients: CFD versus analytical equation
No full textsponsorship: Twan van Hooff is currently a postdoctoral fellow of the Research Foundation-Flanders (FWO) and acknowledges its financial support (project FWO 12R9718N). The authors acknowledge the partnership with ANSYS CFD. (Research Foundation-Flanders (FWO)|FWO 12R9718N)status: Publishe
Simulating building integrated photovoltaic facades: Comparison to experimental data and evaluation of modelling complexity
No full textsponsorship: This work has been conducted within the EFRO SALK project, supported by the EU, ERDF, Flanders Innovation & Entrepreneurship and the Province of Limburg. The authors acknowledge the important collaboration with the Department of Electrical Engineering (ESAT) from KU Leuven as well as with the PV research group from imec. The authors also recognise the important role of our technicians Wim Bertels, Patricia Elsen, and Jimmy Van Criekingen, regarding the experimental work. Twan van Hooff is currently a postdoctoral fellow of the Research Foundation - Flanders (FWO), Belgium and acknowledges its financial support (project FWO 12R9718N). (EU, ERDF, Flanders Innovation & Entrepreneurship, Province of Limburg, FWO|12R9718N)status: Publishe
A physics-based high-resolution BIPV model for building performance simulations
No full textsponsorship: This work has been conducted within the EFRO SALK project, supported by the EU, ERDF, Flanders Innovation & Entrepreneurship and the Province of Limburg. Within this project, the authors acknowledge the collaboration with the Department of Electrical Engineering (ESAT) from KU Leuven as well as with the research group PV modules and systems from imec. Regarding the experimental work, the authors also recognise the important role of our technicians Wim Bertels, Patricia Elsen and Jimmy Van Criekingen. Twan van Hooff is currently a postdoctoral fellow of the Research Foundation Flanders (FWO) and acknowledges its financial support (project FWO 12R9718N). (EU, ERDF, Flanders Innovation & Entrepreneurship, Province of Limburg, FWO|12R9718N)status: Publishe
Cross-ventilation in a generic isolated building equipped with louvers: wind-tunnel experiments and CFD simulations
Full text linkNatural ventilation can be used to improve indoor air quality, remove contaminants from spaces and to remove heat from a building during the day, or during the night. In some cases, openings for natural ventilation are equipped with shading devices – such as louvers – to reduce solar heat gains while allowing natural ventilation. This study presents wind-tunnel experiments and computational fluid dynamics (CFD) simulations of a cross-ventilated building equipped with louvers. Four opening positions are studied: (i) openings in the center, (ii) upper or (iii) lower part of the windward and leeward facades or (iv) one opening in the upper part of the windward facade and one opening in the lower part of the leeward facade. The 3D steady Reynolds-averaged Navier-Stokes (RANS) simulations are performed with three turbulence models (RNG k-ε, SST k-ω, RSM) and validated with the wind-tunnel experiments. The experimental results show that the largest velocities occur in a building with openings in the upper part of the facade. The best agreement with experimental data is provided by RSM. In addition, CFD simulations for buildings without louvers are conducted for the same opening positions to evaluate the effect of louvers on the dimensionless volume flow rate, age of air and air exchange efficiency. The highest dimensionless volume flow rate at reduced scale (0.69) is obtained in the building with louvered openings in the upper part of the facade and the highest air exchange efficiency is achieved for a building with louvered openings in the center of the facade (45%)
Wind-tunnel experiments on cross-ventilative cooling in a generic isolated building with one heated wall: impact of opening size
Full text linkThis paper presents wind-tunnel experiments of cross-ventilative cooling in a generic isolated building with an interior heated side wall. Two different sizes of openings are considered: large and small openings. Particle image velocimetry (PIV) is used to determine velocities in the vertical centerplane. Air temperatures in the vertical centerplane are measured using negative temperature coefficient (NTC) sensors. Surface temperatures on the heated wall are measured using an infrared camera. Surface heat fluxes are obtained using heat flux sensors. In both cases the indoor airflow is dominated by the jet through the openings, with higher velocities in the building with large openings. The air temperatures measured with small openings are up to 7.5 % larger than those with large openings. The surface heat fluxes are up to 20 % higher in the building with large openings. The interior convective heat transfer coefficients vary considerably across the heated wall for both opening sizes and can be very different (up to 5 times higher) from those obtained by existing internal convective heat transfer coefficient correlations. The measurement results give insight into the complexity of ventilative cooling and can be used to validate computational fluid dynamics (CFD) simulations of cross-ventilative cooling
PIV measurements of opposing-jet ventilation flow in a reduced-scale simplified empty airplane cabin
Full text linksponsorship: The Research Foundation - Flanders (FWO) is gratefully ac-knowledged for their financial support of the PhD fellowship of Jo-Hendrik Thysen (project FWO 1150617N) , the post-doctoral fellowship of Twan van Hooff (project FWO 12R9718N) , and the funding for the development of the experimental set-up (FWO 1518517N) . The authors are grateful to Airbus for supporting the measurement campaign. Special thanks go to Jan Diepens, Geert-Jan Maas and Stan van Asten, members of the Laboratory of the Unit Building Physics and Services at Eindhoven University of Technology, and Ad Holten, member of the Laboratory of the Fluids and Flows (F&F) section at Eindhoven University of Technology, for their valuable contributions. (Research Foundation - Flanders (FWO)|FWO 1150617N, Research Foundation - Flanders (FWO)|FWO 12R9718N, Research Foundation - Flanders (FWO)|FWO 1518517N)status: Published onlin
Air curtain performance: Introducing the adapted separation efficiency
Full text linkAir curtains (ACs) are plane turbulent impinging jets that are used to separate two environments in terms of heat and mass transfer while still allowing traffic between these environments. The many applications of ACs across a wide variety of industries makes the evaluation of their performance an important but difficult task. The aim of this paper is to introduce a performance indicator, called the adapted separation efficiency, that is suitable for different types of systems that may involve different AC configurations (downward blowing, upward blowing, lateral blowing, multiple jets, etc.) at multiple scales, different transported quantities (heat, water vapor, particles, gases, etc.) subjected to various transport mechanisms (advection, molecular and turbulent diffusion) and varying environmental conditions (gradients in environmental pressure and/or density). It is defined using a conventional efficiency formula. The principle of this performance indicator is illustrated with a generic case study where the performance is evaluated for two basic AC configurations involving cross-jet pressure and density gradients, as well as different jet momentum fluxes. The case study is conducted based on computational fluid dynamics employing validated large eddy simulations.sponsorship: The Research Foundation - Flanders (FWO) is acknowledged for the financial support of the first author (project FWO G085618N). In addition, Twan van Hooff is currently a postdoctoral fellow of the Research Foundation - Flanders (FWO) and acknowledges its financial support (project FWO 12R9718N). This work was sponsored by NWO Exacte Wetenschappen (Physical Sciences) for the use of supercomputer facilities, with financial support from the Nederlandse Organisatie voor Wetenschappelijk Onderzoek (Netherlands Organization for Scientific Research, NWO). Finally, the authors gratefully acknowledge the partnership with ANSYS CFD. (Research Foundation - Flanders (FWO)|FWO G085618N, Research Foundation - Flanders (FWO)|FWO 12R9718N, NWO Exacte Wetenschappen (Physical Sciences), Nederlandse Organisatie voor Wetenschappelijk Onderzoek (Netherlands Organization for Scientific Research, NWO))status: Publishe
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