Corrado Schenone

Boiling of saturated FC-72 on square pin fin arrays☆

Abstract Pool boiling heat transfer from finned copper surfaces immersed in a saturated dielectric fluid (Fluorinert FC-72) has been experimentally studied. Twelve extended surfaces with different geometrical configurations were tested. Each extended surface consisted of an array of pin fins with square cross-section. Fins were 3 or 6 mm long and their width varied from 0.4 to 1.0 mm. Fins were uniformly or non-uniformly spaced on the base surface: starting from the uniform configuration, in which the width and the spacing of fins were equal, non-uniform surfaces were obtained by regularly removing some rows of fins. For each extended surface, boiling curves were obtained at three different saturation pressures: 0.5, 1.0 and 2.0 bar. The effects of fin dimensions, spacing and pressure on heat transfer in saturated pool boiling were examined. In particular, the effect which the non-uniform distribution of fins produces on boiling behaviour was analysed. When fins thin out, the overall heat transfer coefficient based on the total area of the extended surface increases, but the heat transfer rate does not improve, even in the boiling region close to the maximum heat flux. The better wetting of the boiling surface by the liquid refrigerant, as a result of the sparser grouping of fins, is apparently offset by the reduction in the heat transfer area. If pressure is increased, the boiling curves of finned surfaces move towards lower wall superheats, as already observed in previous studies with regard to both plane and finned surfaces.

Normative framework for ship noise: Present and situation and future trends

The paper addresses the present regulatory framework regarding ship noise emissions both towards the internal spaces onboard and the external environment (in air and in water). A different level of development has been reached in the various areas for the definition of the needs for the noise control and for their implementation in a normative framework. This is due in part to the different point in time in which the different aspects were recognised to be relevant and therefore studied, assessed and regulated. The analysis of existing regulations is the basis for considering the present situation, on-going developments and possible future trends as regards the evaluation of ship noise impact on the various types of environment. The situation of the requirements developed for the maritime field appears to be in line with other fields of engineering as regards the definition of noise limits for the working environment, while the definition of comfort of living on board seems to be somehow lacking behind other fields, with possibility of taking advantage of their experience. Well established assessment procedures for external radiation in air appear to be not yet available and in this case a need for specific developments arises. Finally, for underwater noise emissions, there is availability of relatively well developed requirements, that however are not adequately correlated to the quantification of the effects of the noise emissions on the marine fauna.

The preparation of the Sustainable Energy Action Plan as a city-level tool for sustainability: The case of Genoa

To ensure European Union (EU) commitments to the Kyoto protocol, on 29 January 2008 the European Commission launched the Covenant of Mayors (CoM). This is an initiative aimed at unilateral and voluntary participation of European cities in energy efficiency improvement, renewable energy source usage increase, and greenhouse gas emission reduction by 2020. The Municipality of Genoa, Italy, joined the initiative on February 2009 and its Sustainable Energy Action Plan (SEAP), aimed at a 23.7% CO2 reduction by 2020, has been the first among European cities to be officially published by the European Commission. Following a description of EU environmental policies concerning the energy sector and related regulatory framework, this paper presents issues of CoM and SEAP from an overall standpoint and their application in the city of Genoa. The SEAP approach and criteria, initially considered at a general level, are then analyzed in detail with their operational consequences regarding the city. The Baseline Emissio...

A finite element model to predict sound attenuation in lined and parallel-baffle rectangular ducts

The present article describes a Finite Element Model (FEM) model for the analysis of sound attenuation in lined and parallel-baffle rectangular ducts. By means of the numerical model it was possible to predict insertion losses in a frequency range up to 8000 Hz. The model was validated by comparing numerical results with experimental data obtained in accordance to EN ISO 11691 and EN ISO 7235 standards. For the lined ducts both lining thickness and physical properties of lining were varied during validation; the comparison indicates a good accuracy of the numerical model for all different tested conditions. The results of the validation for parallel-baffle rectangular ducts show that also the behaviour of these dissipative/reactive silencers, with their internal-reflections and energy dissipation phenomena, can be predicted quite well by the FEM model on the whole frequency range. Overall comparisons suggest that FEM modelling can be an accurate and inexpensive way to predict sound attenuation in lined ducts and parallel-baffle mufflers.

Pool boiling heat transfer of dielectric fluids for immersion electronic cooling: effects of pressure

Experiments on nucleate saturated pool boiling were performed on dielectric fluids suitable for direct-immersion cooling of electronic devices. Four different fluids of three families were investigated: perfluoropolyetheres HT-55 and HT-70, perfluorocarbon FC-72, and chlorofluorocarbon R-113. Experiments were carried out on a plane horizontal surface made of copper. The effects of pressure on boiling curves and heat transfer coefficients were studied. Increasing pressure enhanced boiling performance and affected the nucleate boiling hysteresis for increasing and decreasing heat fluxes.

Experimental study on sound absorbing performance of rubber crumb

The present paper describes an experimental campaign aimed at the determination of acoustical properties of vulcanized rubber crumbs obtained by the shredding of used tires. In particular, their performance as sound absorbing material in lined ducts has been investigated. The most innovative aspect that is addressed in the study is the use of a waste material such as rubber tires reduced into small grains as a sound absorbing material: tires are in fact usually used at the end of their life cycle as fuel and burned in cement kilns in order to take advantage of their high heating value, with all the problems of pollution that this solution produces. Two kinds of rubber crumbs have been investigated in terms of characteristic dimension of the grains, porosity, and sound absorbing coefficient, while their “in situ” performance when used inside lined and parallel-baffle rectangular ducts has been evaluated measuring their insertion loss. The results of this research show that the acoustical behavior of the te...

Holistic control of ship noise emissions

Abstract The sustainability of anthropogenic activities at sea is recently gaining more and more attention. As regards shipping, emissions from ships into the environment of various nature (engine exhaust gases, anti-fouling paints leaching, ballast exchange, releases at sea of oil and other noxious liquid or solid cargoes, of sewage and of garbage) have been recognized as sources of pollution and therefore controlled and limited since a long time. The subject of noise emission has been identified only recently. To study the problem, the EU has funded, among others, the FP7 SILENV (Ship Innovative soLutions to rEduce Noise and Vibrations) project that run from 2010 to 2012. In the present work, the holistic approach followed within the project to characterize and control the ship as a source of noise is presented. Three types of noise emissions (in air, in water and inside the ship) are analyzed highlighting peculiarities and different strategies adopted to characterize the source, the impact on the receiver and the possible solutions to set limits to the ship emissions. The project outcome included a socalled “Green Label”: a set of new prenormative requirements defined for the three main areas mentioned above.

The impact of environmental noise generated from ports: outcome of MESP project

Abstract Ports are characterized by several complex operations. Accordingly, the analysis of noise results is complicated due to the presence in the same area of diverse sound from ships, trade and also from industrial and shipyards activities aswell as auxiliary services producing negative effects on natural ecosystem and the urban population. The ENPI CBC MED project Managing the Environmental Sustainability of Ports for a durable development (MESP) addressed the pollution reduction from port activities through the implementation of a multidisciplinary approach in air, noise andwater sectors, encompassing technological, regulatory and administrative solutions to ensure natural and urban sustainability and high level of life quality in surrounding territories. To prevent a heterogeneous development, the “status quo” of ports in Northern and Southern Shores of the Mediterranean Sea was analyzed and a guideline on methodologies, good practices and measurement assessment, adaptable and transferable in different port contexts was elaborated. To assess the procedures, validation tests have been carried out to different real cases. In noise sector pilot projects in the ports of Patras, Greece, and Tripoli, Lebanon, have been implemented. Due to the dissimilar scenarios, in terms of orography, facilities and activities, different noise mitigation actions and interventions were consequently accomplished.

Acoustical study of historical large room for a contemporary use: The oratory of Albergo dei Poveri in Genova

The conversion of deconsecrated religious buildings in conference halls or music auditoria is nowadays frequent, especially throughout Italy and Europe, although in most cases these rooms are under artistic and architectural preservation due to their historical heritage value. In this way, acoustic control interventions in such spaces, generally characterized by high reverberation time values, tend to be highly complex. The Oratory of “Albergo dei Poveri” building in Genova, transformed during the 90s in the Auditorium of the Departments of Law and Political Sciences of the University of Genova, faced these needs. After several interventions regarding the installation of sound systems and acoustical curtains, nowadays the acoustical features of the room are not still sufficient for the achievement of the adequate acoustic comfort. In this paper, the acoustic analysis of the hall has been evaluated and effective correction interventions at the same time compliant and non-invasive with the architectural con...

Noise Mapping of the Flyover Highway in Genoa:comparison of different methods

Abstract In urban noise mapping the accuracy of the simulation tools is often challenged by the complexity of the modeled scenario, particularly when its extent coincide with the whole city. In this paper, a meaningful case study is reported concerning the flyover highway “Aldo Moro” in Genoa. The particular morphology of the city and the location of the highway make it a significant test for analyzing the effectiveness of current modeling tools in simulating complex urban areas. Noise mapping has been implemented in accordance with the standardNMPB-Routes- 2008. Results have been then analyzed complying with the END. Next diverse computational methods have been compared, considering ISO 9613-2, NMPB-Routes-1996, and Harmonoise, and even different frequency partitions (octave band or one-third octave band) for the last two standards. The computational time for the different calculation methods has been analyzed. In order to get a reciprocal validation, the simulated noise maps have been finally compared with maps coming from on field measurements. In this way a case study helpful for public administrations and stakeholders facing similar issues is provided, defining the state of the art and the forthcoming perspectives.