644 research outputs found
Optimal configuration selection through experimental tests on branched heat exchanger with R134 organic fluid
No full textThe aim of this work the analysis of compact branched heat exchangers, by measuring thermal efficiency and the pressure drop in several experimental tests. Three different heat exchanger configuration have been considered. In the first device, the constant efflux velocity, in the internal channels, was imposed. The second exchanger was realized by imposing constant the value of the Reynolds number. The last device was created according to the instructions of the constructal theory. All three exchangers are aluminum made. In addition, in order to have a more detailed knowledge of the phenomenon and to identify what are the parameters that govern heat transfer, an organic fluid has been used and tested. In our case R1234 organic fluid. It was therefore necessary to realize an appropriate test bench for the use of the organic fluid. Once realized, several tests were conducted. Finally in order to be able to indicate which configuration results the optimal one, the Prandtl and Nusselt numbers were obtained and compare
High-performance electric/hybrid vehicle. Environmental, economic and technical assessments of electrical accumulators for sustainable mobility
No full textThe present work aims to provide a technical, economic, and environmental analysis on the electric accumulators used for electric mobility (pure electric, hybrid, full hybrid and/or mild hybrid) to reduce the environmental, social and economic impacts generated by private vehicles. Initially, the scenarios for the development of electric mobility and the regulatory context were assessed. Attention has been focused on the batteries used in electric vehicles and the technological aspects related to their charging operations. With regard to the economic aspects, the evolution of battery costs in relation to capacity and size has been highlighted in recent years. The advantages related to the containment of environmental impacts are highlighted considering the aspects related to the end of life of the batteries themselves. As retrofitting ICE vehicles by electric motor currently represents a potential transition solution to improve the shift towards the widespread adoption of electric vehicles, the retrofit methodology of some of the current B-segment vehicles was evaluated. In the present work, the authors wanted to demonstrate how the solution proposed here, the retrofitting of class B vehicles, can represent a medium-term way to implement the transition from MCI-based traction to electric
Power Generation with Vegetable Oils in the Italian Scenario: A 20 MW Case Study. Technical Feasibility Analysis and Economical Aspects
No full textNowadays the utilization of vegetable oils, particularly the palm oil, as fuel in the power plant, has made a significant development in the last few years. This vegetable oil can be used in particular in slow marine-derived diesel internal combustion engine (ICE), with an electric efficiency of about 40%. The efficiency is connected to the size of the power plant. Moreover, the considerable amount of the required vegetable oil to feed the system forces, especially in Italy, makes it necessary to import the fuel. This is the most critical element as the palm oil is subject to continuous variations in prices. Due to this variation it is difficult to stabilize a convenient fuel supply for a long period. The paper aims to evaluate and estimate the economic, technical and environmental feasibility of a 20 MW plant for the stationary power generation fed with palm oil, enlightening the system solution (technical constructive aspects) and the economic ap- praisal, on the basis of variations in oil prices. A comparison with a cogenerative power plant has been also carried out and, at last, the economic sensibility analysis based on the fuel cost and the European mechanisms of biomass incen- tives is performed
A PROPOSAL FOR POWER QUALITY MANAGEMENT PROTOCOL IN RESIDENTIAL BUILDINGS WITH CO-GENERATIVE AND RENEWABLE SYSTEMS
No full textThe aim of this paper is to describe a management protocol for electrical and thermal loads in housing scheme equipped with co-generative unit and renewable system. In new residential buildings is very important the presence of co-generative unit and renewable system to turn from the actual electrical grid (passive) into a smart grid; in fact, nowadays few power plants satisfy all customer electric demands; whereas in the near future the electrical final users will became local power producers. The new management protocol allows to optimize the energy demands in according with electrical energy cost, depending on time slot, and the instant power generation from co-generative and renewable devices. This system is capable, by simplex domotic interface, described analyzed and design by the authors, to individuate the more convenient time for the users, to respond at their energy demands. The advantage of this system can be found on a new power quality management, with consequent cost decrease for the users. Copyright © 2012 by ASME
In margine ai Valdesi di Calabria. Nota bibliografica per un dibattito storiografico
No full textE' apparso utile, all'interno di una più ampia riflessione critica intorno alla vicenda valdese svoltasi in Italia tra il secondo Medioevo e la prima età moderna, porre l'accento, in sede convegnistica, sul recupero di alcuni testi apparsi in prevalenza su giornali, riviste, atti di convegni ecc., tra il 1950 ed il 1990. Si tratta di scritti poco noti e, pertanto, scarsamente utilizzati dagli storici professionali o dai più semplici cultori di storia locale, il cui valore essenziale è però, quello di offrire, oggi, spunti per un dibattito storico e storiografico sui lineamenti di una minoranza religiosa, i Valdesi, la cui vicenda umana e di fede pure appartiene ad alcuni sviluppi ancora poco noti della storia d'Italia
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