No abstract

The environmental impacts of sport events have been growing during the last decades, which has led to the organizing associations developing adequate countermeasures to both reduce carbon emissions due to construction and operational stages compensate for the emissions. This work aims at proposing an approach to stadiums energy enhancement that includes strategies largely recognized as effective and applicable to several building typologies (residential, commercial, academic, etc.). The selected case study is the Dacia Arena in northern Italy that has been recently refurbished and renovated. The proposed workflow has as a goal minimizing the increment of the operational emissions, caused by new heated areas in the stadium. Firstly, the energy consumption was estimated in dynamic state for Scenario 0 (current state) and Scenario 1 (refurbished state) to quantify the new plant’s energy demand. Secondly, two hypothetical system layouts were proposed and evaluated. In the first, the power for lighting, cooling and heating is supplied by a system that couples photovoltaic panels with heat pump. In the second, the same photovoltaic plant is integrated with a biomass plant and an absorption chiller. The comparison highlights the suitability of those interventions and the environmental advantages deriving from their exploitation.

Spray impingement on smooth and heated surfaces is a highly complex thermofluid phenomenon present in several engineering applications. The combination of phase Doppler interferometry, high-speed visualization, and time-resolved infrared thermography allows characterizing the heat transfer and fluid dynamics involved. Particular emphasis is given to the use of nanofluids in sprays due to their potential to enhance the heat transfer mechanisms. The results for low nanoparticle concentrations (up to 1 wt.%) show that the surfactant added to water, required to stabilize the nanofluids and minimize particle clustering, affects the spray’s main characteristics. Namely, the surfactant decreases the liquid surface tension leading to a larger wetted area and wettability, promoting heat transfer between the surface and the liquid film. However, since lower surface tension also tends to enhance splash near the edges of the wetted area, the gold nanospheres act to lessen such disturbances due to an increase of the solutions’ viscosity, thus increasing the heat flux removed from the spray slightly. The experimental results obtained from this work demonstrate that the maximum heat convection coefficients evaluated for the nanofluids can be 9.8% to 21.9% higher than those obtained with the base fluid and 11.5% to 38.8% higher when compared with those obtained with DI water.