Fabio Nardecchia

A novel approach to CFD analysis of the urban environment

The construction of cities, with their buildings and human activities, not only changes the landscape, but also influences the local climate in a manner that depends on many different factors and parameters: weather conditions, urban thermo-physical and geometrical characteristics, anthropogenic moisture and heat sources. Land-cover and canopy structure play an important role in urban climatology and every environmental assessment and city design face with them.Inside the previous frame, the objective of this study is both to identify both the key design variables that alter the environment surrounding the buildings, and to quantified the extension area of these phenomena. The tool used for this study is a 2D computational fluid dynamics (CFD) numerical simulation considering different heights for buildings, temperature gaps between undisturbed air and buildings walls, velocities of undisturbed air. Results obtained allowed to find a novel approach to study urban canopies, giving a qualitative assessment on the contribution and definition of the total energy of the area surrounding the buildings.

Home smart grid device for energy saves and failure monitoring

The growing sensibility on energy consumption has focused people interest in energy optimization technologies. Non-intrusive load monitoring system (NILMS) are a cheap solution that require minimal equipment and installation time. The aim of the research is to develop a load analyzing platform for electrical devices to obtain information on their functionality and to display the costumer advantage to change their energy class. It monitors malfunctions or non-critical failures in real-time. It also counts the device operative life-time. The architecture is made of a local analysis electrical plug, which get the load information, and a central unit which elaborates data. The hardware implements a hall-effect ammeter, a power transformer and a micro controller (AT-mega328). The central unit is a small integrated computer (Raspberry). The communication between the devices utilize a low-range radio transmitter.

A quantitative evaluation of the mutual influences among Smart strategies applied at district level

Cities play an important role in reducing greenhouse gas emissions and improving energy efficiency. The Smart City concept, applied at different territorial levels, is one of most famous frameworks for improving the performance of cities. Smart planning models should allow to identify solutions in a coordinated and holistic way. Starting from these considerations, in this paper the authors focused on the quantitative evaluation of the mutual influences among Smart strategies applied at district level. An ideal sustainable district was analyzed and two improved scenarios (Smart interventions on buildings and green areas) were carried out. The aim is to evaluate if and to what extent these actions would have an impact form energy, environment end economy points of view compared to the base case scenario. Simulation results of the three scenarios show significant differences from energy, environmental and economic perspectives.

An alternative tool for the energy evaluation and the management of thermal networks: The exergy analysis

In the context of the strategy “Europe 2020”, European Directive 2012/27 identifies the high efficiency cogeneration and the district heating and cooling as instruments to reach the energy efficiency goals. The great potential deriving from these solutions is basically linked to the possible use of Renewable Energy Sources (RES) rarely used in centralized energy production. In literature many energy, economic or environmental indexes for the evaluation of energy networks efficiency are available. Notwithstanding, these indexes, based on primary energy savings, are less reliable when generation system powered by RES are analyzed. The goal of this work is the introduction of exergy as an alternative evaluation tool for the characterization of the thermal energy networks efficiency. In this research a parametric analysis has been carried out based on a Simulink [1] model. This model simulates the dynamic behavior of an energy micro-grid dedicated to three different buildings. The simulations have been run for three cities located in different climatic zones. Results show the positive impact of exergy as a tool to evaluate energy networks powered by traditional and renewable energy sources.

CFD Analysis of Urban Canopy Flows Employing the V2F Model: Impact of Different Aspect Ratios and Relative Heights

Computational fluid dynamics (CFD) is currently used in the environmental field to simulate flow and dispersion of pollutants around buildings. However, the closure assumptions of the turbulence usually employed in CFD codes are not always physically based and adequate for all the flow regimes relating to practical applications. The starting point of this work is the performance assessment of the V2F (i.e.,  − f) model implemented in Ansys Fluent for simulating the flow field in an idealized array of two-dimensional canyons. The V2F model has been used in the past to predict low-speed and wall-bounded flows, but it has never been used to simulate airflows in urban street canyons. The numerical results are validated against experimental data collected in the water channel and compared with other turbulence models incorporated in Ansys Fluent (i.e., variations of both k-e and k-ω models and the Reynolds stress model). The results show that the V2F model provides the best prediction of the flow field for two flow regimes commonly found in urban canopies. The V2F model is also employed to quantify the air-exchange rate (ACH) for a series of two-dimensional building arrangements, such as step-up and step-down configurations, having different aspect ratios and relative heights of the buildings. The results show a clear dependence of the ACH on the latter two parameters and highlight the role played by the turbulence in the exchange of air mass, particularly important for the step-down configurations, when the ventilation associated with the mean flow is generally poor.

Sapienza smart campus: From the matrix approach to the applicative analysis of an optimized garbage collection system

University campuses can be developed and improved through the application of the Smart concept. Previous researches have proposed a Smart Campus model based on incidence matrices in order to choice suitable integrated strategies. This methodological framework has been applied on the headquarter of Sapienza, University of Rome. The winner strategy resulting from the Environmental evaluation has been numerically simulated and the results have shown their impacts in terms of energy, environmental and economic perspectives.

CFD analysis of onshore oil pipelines in permafrost

Underground pipelines are built all over the world and the knowledge of their thermal interaction with the soil is crucial for their design. This paper studies the “thermal influenced zone” produced by a buried pipeline and the parameters that can influence its extension by 2D-steady state CFD simulations with the aim to improve the design of new pipelines in permafrost. In order to represent a real case, the study is referred to the Eastern Siberia-Pacific Ocean Oil Pipeline at the three stations of Mo’he, Jiagedaqi and Qiqi’har. Different burial depth sand diameters of the pipe are analyzed; the simulation results show that the effect of the oil pipeline diameter on the thermal field increases with the increase of the distance from the starting station.Underground pipelines are built all over the world and the knowledge of their thermal interaction with the soil is crucial for their design. This paper studies the “thermal influenced zone” produced by a buried pipeline and the parameters that can influence its extension by 2D-steady state CFD simulations with the aim to improve the design of new pipelines in permafrost. In order to represent a real case, the study is referred to the Eastern Siberia-Pacific Ocean Oil Pipeline at the three stations of Mo’he, Jiagedaqi and Qiqi’har. Different burial depth sand diameters of the pipe are analyzed; the simulation results show that the effect of the oil pipeline diameter on the thermal field increases with the increase of the distance from the starting station.