Giuseppe Langella

Advanced Image Analysis of Two-Phase Flow inside a Centrifugal Pump

The analysis two-phase flow inside centrifugal pumps is a fundamental issue in several engineering applications. This often represents a bad working condition with respect to single phase one, causing head reduction, efficiency decrease, and higher operational costs in terms of energy and money. The paper reports a numerical analysis of bubbles behavior inside centrifugal pumps. Equations regulating the air bubble motion within the rotor of a centrifugal pump have been solved considering the effects of all forces acting. Coalescence phenomena have been investigated too, in order to identify how gas zone presence in the rotor can lead to anomalous working condition. Results are reported in graphs and diagrams varying bubble dimension and water flow rate. An experimental approach to visualize the two-phase flow field inside the impeller is presented too. Images have been acquired, elaborated, compared with numerical results, and discussed in order to understand the interaction between gas phase and liquid phase and to correlate this behavior with the energy dissipation phenomena for a centrifugal pump.

A numerical approach to assess air pollution by ship engines in manoeuvring mode and fuel switch conditions

Due to increasing worldwide trade, transportations of goods through seaports have been gradually growing in the past years; harbours are main centres of economic activities, with unavoidable consequences on the air quality degradation and human health of many urbanized ports. This study provides a methodology to assess the impact of pollutant emission from marine engines on ambient air quality of the coastal areas. The environmental pollution from sea traffic was evaluated by assessing the production and atmospheric dispersion of exhaust emissions produced by ship engines in manoeuvring mode and in fuel switch conditions from heavy-sulphur residual fuel oil to low-sulphur distillate fuel oil. Specifically, this study analyses the emissive behaviour of merchant ships, equipped with large size diesel engines and transiting in the port of Naples, which is located very close to the densely populated urban centre. The spatial distribution of the air pollutant concentrations was calculated with a specific dispersion modelling approach, delivering significant data about the environmental impact of merchant ship emissions on the coastal urban area. The NOX, PM and SOX pollutant concentrations estimated with this methodology were also compared with pollution levels measured in an experimental monitoring campaign performed in the port of Naples. Estimated concentration levels were lower than measured values because the latter were affected by other anthropogenic emissive sources adjacent to port area, above all exhaust emissions from the road transport sector. Both the calculated and measured concentration levels over coastal area were below the European Limit Values.

Comparative Exergetic Analysis of Solar Integration and Regeneration in Steam Power Plants

AbstractNowadays, many health, environmental, and economic concerns are associated with fossil fuel use, and therefore the improvement of new and advanced technologies and the use of renewable fuel...