Heating Ventilating and Air Conditioning, Infiltration and Ventilation, Environmental Flows in Urban Environment, Solar and Geothermal HVAC systems.

# Bouris

Demetri Bouris

**Title:**Assistant Professor

**Country of residence:**Greece

**Institution:**National Technical University of Athens – School of Mechanical Engineering

**Role:**MC Member

**Address:**9 Heroon Polytechniou 15780, Athens, Greece

**Email:**dbouris@fluid.mech.ntua.gr

**Telephone:**+30 210 7724339

**Date of birth:**15/10/1968

**Early Stage Researcher:**No

**Sex:**Male

**MC Member:**Yes

**WG membership:**

1, 2, 4

**Publications**

- D. Bouris, T. Theodosiou, K. Rados, M. Makrogianni, K. Koutsoukos and A. Goulas (2010) «Thermographic Measurement and Numerical Weather Forecast Along a Highway Road Surface», Meteorological Applications, 17, 474–484

Effective winter maintenance of motorways is highly dependent on local topography and weather and can be a significant economic factor in overall maintenance costs. In the present paper, a temperature profile of a highway road surface is obtained through infrared thermography measurements and then compared to numerical weather forecasts using the COAMPS (Coupled Ocean/Atmosphere Mesoscale Prediction System) mesoscale weather prediction model. The highway under examination is a 26 km portion of the Egnatia motorway in northern Greece, which includes a number of twin-bore tunnels and cantilever bridges. Points of significant temperature variation are found at tunnel exits but the trend in the temperature profile is similar over different days of observations. Comparison of mesoscale numerical forecasts

with measured values of air and road surface temperature shows encouraging agreement under typical clear winter night conditions with moderate wind. This suggests that current weather prediction modelling capabilities may be acceptable as a useful first approximation but also shows the gap that must be filled for accurate prediction of local road surface conditions. - M. Petridou, Y. Perivolaris, D. Bouris (2010) “Numerical Simulation of Wind Flow in the Urban Environment”, Proc. RΟΗ-2010 7th National Conference for Research Activities in Fluid Flow Phenomena in Greece, Thessaloniki, 12-13 November, 2010.

The study focuses on the investigation of wind flow in the urban environment for the optimization of applications such as natural ventilation and infiltration in buildings, building integrated wind power etc. The goal is to develop a numerical methodology that will facilitate urban geometry representation and the subsequent simulation of the wind flow throughout it. Due to the different length scales present in these applications, the numerical approach includes a multiple local grid refinement methodology, applied to Cartesian grids, for economy of computational resources. The methodology is first applied to a simplified cubic building envelope with openings and five different turbulence models are implemented (k-ε, MMK, RNG, k-ω and SST). The final application is to a 6 block area (160x160 m2) in Piraeus, which was geometrically represented in Cartesian coordinates with the aid of an in-house methodology implementing Google Building Maker - F. Barmpas, D. Bouris, N. Moussiopoulos (2009) “3D Numerical Simulation of the Transient Thermal Behavior of a Simplified Building Envelope Under External Flow”, Journal of Solar Energy Engineering, 131, 3, 031001

Understanding building envelope performance and thermal mass effects is becoming increasingly important under the scope of low energy building construction and energy conservation. In the present paper, a three-dimensional computational fluid dynamics methodology is presented for the numerical simulation of the flow and heat transfer that determine the thermal behavior of simplified building envelopes. This is dominated by a conjugate heat transfer approach, which involves conduction, convection, solar heat gains, ambient temperature variation, and the effects of thermal radiation losses to the sky. Validation results include comparison both with measurements from fundamental laboratory studies of heat transfer from surface mounted cubes and with numerical results from well established commercial building energy simulation software. Numerical issues, such as temporal and spatial discretization, are addressed, and parametric studies are performed with regard to the effect of external flow Reynolds number and temperature variation in the building envelope, depending on the individual orientation of the external walls with respect to the flow and on the thermal properties of the building materials. Results from the parametric studies performed indicate that the transient three-dimensional calculations provide important information regarding the effect of external flow properties, such as the approaching flow temperature, velocity, and direction on the thermal behavior of the building envelope. In addition, it has been clearly demonstrated that the methodology is also capable of taking into account the complex effects of parameters such as the building material properties. - K. Chatziangelidis and D. Bouris (2009) “Calculation of the Distribution of Incoming Solar Radiation in Enclosures”, Applied Thermal Engineering, 29, pp. 1096-1105

Solar heat gains are an important factor in the calculation of cooling loads for buildings. This paper aims at introducing an improved methodology to calculate the distribution of incoming solar energy on the internal surfaces of closed spaces with multiple openings. The independent numerical methodology is based on the view factor theory and in order to justify and prove its functionality, it has been linked to the commercial software of TRNSYS, which normally uses a surface area ratio based algorithm for the same process. For the simplified building structures that have been examined, there are noticeable differences in the spatial and temporal distribution of the absorbed solar energy. The proposed approach is indeed an improvement over the surface area ratio method, having a strong physical basis with relatively little extra computational effort - C. Tatatzikidis, S. Piperidis, D. Bouris (2009) “Experimental Measurement and 3D Numerical Simulation for the Characterisation of Building Infiltration”. 5th Int.Conf. on ENERGY, ENVIRONMENT, ECOSYSTEMS and SUSTAINABLE DEVELOPMENT(EEESD'09) Vouliagmeni Beach, Athens, Greece, September 28-30, (Astir Palace Hotel), paper: 619-215. (Best Paper Award)

An experimental and numerical study of the air-tightness level of the building of the Department of Mechanical Engineering, University of Western Macedonia, Kozani, Greece was performed. Air permeability was measured with a Blower Door and a comparison of the results with European and International standards was performed. The Effective Leakage Area (ELA) of each room of the building was determined and the results were used as input data for the computational study. Openings equivalent to the ELA were included in the building geometry and a computational fluid dynamics methodology was used to perform a three dimensional simulation of the air flow inside and around the building. A comparison of the measured and the simulated infiltration rate was performed and the effect of the distribution of leakage area on the building shell has been examined. - C. Albanakis and D. Bouris (2008) “3D conjugate heat transfer with thermal radiation in a hollow cube exposed to external flow”, International Journal of Heat and Mass Transfer, 51, pp. 6157-6168

The interaction of an asymmetrically heated cube envelope exposed to turbulent external flow is numerically studied using a three dimensional computational fluid dynamics control volume approach with conjugate heat transfer, including thermal radiation effects. An analytical approach is used for thermal radiation modelling with an implicit boundary condition for convective and radiative heat transfer at solid–fluid interfaces. For external flow Reynolds numbers of 2 105–106 and heat flux values of q = 20, 40Wm-2, a weak but turbulent (Ra = 1.5–5 109) buoyant flow is induced inside the cube. The temperature distribution of the inner surfaces is significantly affected by heat flux orientation with regard to external flow as well as the relative influence of convective and thermal radiation heat transfer. - M. Petridou and D. Bouris (2006) “Experimental and Numerical Study of the Effect of Openings on the Surface Pressure Distribution of a Hollow Cube”, WSEAS Transactions on Fluid Mechanics, Vol. 1, Iss. 6, pp. 655. ISSN 1790-5087

Infiltration and natural ventilation for a simplified cubic building structure is considered through an experimental and numerical study of building envelope surface pressure distribution, as affected by openings on its vertical sides. The envelope outer surface pressure distribution is experimentally studied in a wind tunnel, using a plexiglass hollow cube model and varying the relative positions of the openings. The measurements are subsequently used for validation of a computational fluid dynamics methodology. Turbulence was modelled using a modification to the standard k-ε model for improved accuracy in flows past bluff bodies. Results indicate significant influence of the relative positions of the openings in the variation of the pressure distribution, as compared to the case of a solid cube. Sabstantial improvement in the predictions is observed when using the modification to the k-ε turbulence model, especially in areas of flow separation following stagnation regions.