Reducing the effect of urban heat island

Page 1

U.P.B. Sci. Bull., Series …, Vol. …, Iss. …, 201

ISSN 1223-7027

REDUCING THE EFFECT OF URBAN HEAT ISLAND: A CASE STUDY FOR BUCHAREST, ROUMANIA Adrian CIOCĂNEA1, Andrei DRAGOMIRESCU2, Bogdan TOFAN3, Raluca MANOLACHE4 This paper presents an original solution that aims at reducing the pollution level and the effect of urban heat island (UHI) during the summer season in the city of Bucharest, Roumania, using an outdoor ventilation method. This method is based on lifting air volumes from the free surface of Dâmbovița River that crosses the city center, where the UHI has a significant impact, using cross-flow fans placed on floating structures near the concrete river bank. The electric motors of the crossflow fans are supplied with power by solar cells. A numerical study was performed in order to obtain the flow pattern of the cooler air taken from the water surface and blown towards the concrete embankment and roadway surface. It was observed that at low flow rates the cooler air with higher humidity reaches the roadway surface in a compact jet due to Coanda effect. The height of the coherent air jet is of about 3040 cm. This height equals the mean value of the distance between road surface and vehicle exhaust pipes. Due to the higher humidity of the air jet it is expected that dust and exhaust particles from closely above the road are expected to be better fixed at the ground until street sweepers remove them. In this way, the level of pollution with airborne particles could be reduced. The study opens the possibility to approach such issues at a greater scale in order to assess the viability of appropriate solutions for cooling down the UHI as well.

Keywords: pollution, urban heat island, urban greening, outdoor ventilation, CFD. 1. Introduction Recent studies regarding urbanization issues take more and more into consideration the influence that large urban areas have on climate change, first of all due to the formation of the so called Urban Heat Island (UHI). Consequently, a series of permanently evolving concepts have been defined, such as sustainable development, local sustainability, resiliency, etc. Different strategies were subsequently developed in order to address these issues [1, 2]. The strategies proposed to reduce the influence of UHI were elaborated based on the observed 1

Prof., Dept. of Hydraulics, Hydraulic Machinery and Environmental Engineering, University POLITEHNICA of Bucharest, Romania, e-mail: adrian.ciocanea@upb.ro 2 Assist. Prof., Dept. of Hydraulics, Hydraulic Machinery and Environmental Engineering, University POLITEHNICA of Bucharest, Romania, e-mail: andrei.dragomirescu@upb.ro 3 “Ion Mincu” University of Architecture and Urbanism 4 “Ion Mincu” University of Architecture and Urbanism


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