Modular ventilation with twin air curtains for reducing dispersed pollution

The optimal solution for reducing the level of pollutants remains their trapping close to source. When this possibility is absent, the high degree of pollutant dispersion makes difficult and expensive any process of pollutant trapping and cleaning. This work suggests a new approach regarding the ventilation of urban road tunnels, based on the necessity for such spaces to take advantage of ventilation means which permanently direct the air towards cleaning filters while constraining uncontrolled pollutants dispersion. A concept of a modular ventilation is proposed, in which the air flow is not only induced by intake and/or exhaust fans and random obstacles inside the boundaries, but also confined by means of air curtains generated by cross flow fans. The expected result is a higher efficiency of the ventilation and of the subsequent air cleaning process. To illustrate the concept, a case study was undertaken. The investigations were focused on the behavior of twin air curtains generated by two cross flow fans and forming virtual walls inside an urban road tunnel. The results presented indicate how the distance between the curtains should be chosen, so that they remain stable, how the curtains interact with moving vehicles, and how the vents placed on the tunnel ceiling for exhausting polluted gases should be designed. (c) 2013 Elsevier Ltd. All rights reserved.