Conference Agenda

Overview and details of the sessions of this conference. Please select a date or location to show only sessions at that day or location. Please select a single session for detailed view (with abstracts and downloads if available).

Session Overview
Session 09: Ventilation, heat transfer and CFD
Wednesday, 25/Aug/2021:
2:00pm - 3:30pm

Session Chair: Dr. Parham A Mirzaei, The University of nottingham
Location: Room 5 - Room 019, Building: 116

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2:00pm - 2:15pm


Modar Ali1,2, Ádám László Katona1,2, István Kistelegdi1,3

1Energia Design Building Technology Research Group, Szentágothai Research Centre, H-7624 Pécs, Hungary; 2Breuer Marcel Doctoral School, Faculty of Engineering and Information Technology, University of Pécs, H-7624 Pécs, Hungary; 3Department of Building Structures and Energy Design, Institute of Architecture, Faculty of Engineering and Information Technology, University of Pécs, H-7624 Pécs, Hungary

Buildings are responsible for around 40% of greenhouse emissions globally. The residential building sector is responsible for 24% of energy use. In Hungary, about 800.000 of ‘Cube Houses’ which date back to the socialist era are still standing. These houses are considered to be outdated from the energy point of view. This paper presents a new refurbishment approach that attempts to fulfill the highest sustainability requirements regarding indoor comfort and energy efficiency. The presented aerodynamic design aims to achieve passive cooling by integrating the “Venturi disc” which stimulates natural ventilation and night cooling. The work was achieved by using Computational Fluid Dynamics (CFD) simulations using ANSYS Fluent software tool. The implemented building provides lower energy demand and considerably higher comfort in comparison with the typical ‘Cube House’. The building is not only a case study, rather a sustainable model for all the ‘Cube Houses’ renewal and further family housing renovations or constructions to reach a higher standard. This paper is a step in an ongoing research project.

2:15pm - 2:30pm

On-site measurement and numerical investigation of thermal environment with different air distribution systems in ice arenas

Wenyu Lin, Tao Zhang, Xiaohua Liu, Lingshan Li

Department of Building Science, Tsinghua University, Beijing, China

It is important to strictly maintain the indoor thermal environment in ice arenas which have very different features to other commercial buildings. Separated air distribution system is widely used to create a dry and cold environment near the ice and a comfortable environment in the view stand. The warm and humid air from the view stand may lead to uneven temperature and humidity distribution in the rink, leading to extra energy consumption, even fog and frost on the ice. Unreasonable air supply in the ice rink zone will also make the spectators feel too cold and uncomfortable. Jet ventilation system is the most extensively used system in the ice rink zone. An innovative ground displacement ventilation system is proposed in the National Aquatics Centre, which will serve as the venue for the curling competition in the 2022 Beijing Winter Olympics. On-site measurement in the arena is carried out and computational fluid dynamics (CFD) simulation method is adopted in the present research. Measured thermal environment above the ice with different ventilation systems are compared and analysed. Result shows that the displacement ventilation system features a more obvious vertical stratification than jet ventilation system in this kind of large space buildings, and thus is more energy-efficient. A CFD model of the ice cube is setup and verified by measured data. The thermal environment in the ice rink with displacement ventilation under extreme condition is studied using the simulation method. The temperature and humidity in the ice field increases by 10.1 ℃, 4.5 g/kg without air supply in the view stand, proving that the spectators in the view stand have a great impact on the thermal environment in the ice field.

2:30pm - 2:45pm

A simplified model for calculating heat transfer through the double skin facade

Guoqing He1,2, Yuan Meng1, Jiayi Zhu1, Sanming Zhang1

1College of civil engineering and architecture, Zhejiang University, China; 2Center for Balance Architecture, Zhejiang University, China

Double skin façade (DSF) has been recognized as a flexible type of envelope that can adapt to various building needs, such as insulation, solar heat gain, ventilation, and shading. This adaption ability makes the DSF a potentially high performance envelope. However, the reliable calculation of the heat flow in the DSF has been a challenging task due to the complex heat transfer process involved in the DSF. In this study, we propose a simple model that aims to simplify the heat transfer calculation involved in the DSF. In this model, a characteristic function of heat transfer coefficient (CFHTC) was proposed for the heat transfer between the inner layer and the outside air, which would otherwise call the complex convective heat transfer in the cavity. We use experimental data to demonstrate that this function can be expressed as a function of the incident solar intensity. This CFHTC is supposed to be dependent on the geometry of the DSF. With the CFHTC, the calculation of the heat transfer between the inner layer of the DSF and the outside air is simplified and can be incorporated in energy simulation tools.

2:45pm - 3:00pm

Evaluation and Use of Airspaces for Thermal Resistance in Buildings

Hamed H. Saber1, David W. Yarbrough2

1Prince Saud Bin Thuniyan Research Center, Royal Commission of Jubail and Yanbu, Saudi Arabia; 2R&D Services, Inc., Watertown, TN, USA

The usefulness of enclosed airspaces for thermal resistance has been recognized for well over 100 years. Enclosed airspaces with one or more low-emittance surfaces perpendicular to the heat flow direction define reflective insulation assemblies, a well-known thermal insulation product type used in various building components such as walls, roofs, and double/triple glazing fenestration systems (windows, curtain walls and skylight devices). The thermal resistance (R-value) of an airspace depends mainly on the emissivity of all surfaces that bound the airspace, the dimensions and orientation of the airspace, the direction of heat flow through the airspace, and the respective temperatures of all surfaces that define the space. Assessing the energy performance of building envelopes and fenestration systems, subjected to different climatic conditions, requires accurate determination of the R-values of the enclosed spaces. The evaluation of the thermal performance of reflective insulation assemblies has evolved in recent years to include detailed analysis using computational fluid dynamics coupled with accounting for surface-to-surface radiations to quantify convective and radiation contributions to the overall heat transfer across airspaces classified as reflective or non-reflective.

This presentation will compare an advanced computational tool for calculating the R-value for an enclosed airspace with existing methods used around the world. The existing methods include ISO 6946 and modeling based on hot-box measurements made in the past in North America that are the basis for the reflective airspace R-values contained in the ASHRAE Handbook of Fundamentals. The new tool provides a capability for evaluating construction defects, air-infiltration impact, and dimensional aspect ratios that the earlier one-dimensional methods for calculating R-value do not address. Results for the differences between the methods being used to evaluate thermal resistance will be discussed along with the advantages of the advanced evaluation method for the design of new reflective insulation products and applications.

3:00pm - 3:15pm

Numerical And Experimental Study Of A Supply Air Wall Based On Integrated Insulation Clay Hollow Blocks

Jean-Baptiste BOUVENOT, Matthieu EGG

INSA Strasbourg/ICube Laboratory, France

Integrated insulation clay hollow blocks is an interesting constructive system in the context of Near Zero Energy Buildings and building energy efficiency. Their simple modification into supply air wall can increase their thermal performance without great effort. This paper deals with the creation of an original supply air wall or window test bench and with the numerical and experimental study of a supply air wall (or ventilated wall) based on modified modern integrate insulation clay hollow blocks where large cavities (about 4 cm) are fulfilled by mineral wool. In some cavities, mineral wool is removed to create a flow pattern, which aims to recover heat losses from inside and solar energy from outside. At first, a 3D CFD numerical model is presented to assess the energy performance of a 1 m² sample of ventilated wall. Then, an experimental test bench, based on a modified guarded hot box simulating solar effects and airflows between the two chambers, is carried out to assess the real performances. A comparison between these two studies allows validating the results which show a good correlation in terms of temperature difference gains between outdoor temperature and pre heated temperature going up to a maximum of 14 K for only 1 m² of wall and for a volume flow rate of 4 m3/h (4,5 K for 32 m3/h).

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