Search results for "efficiency."
showing 10 items of 1362 documents
Sustainability issues in sheet metal forming processes: an overview
2011
Abstract Environmental sustainability in manufacturing is nowadays an urgent and remarkable issue and the main concerns are related to more efficient use of materials and energy. In sheet metal forming processes there is still a lack of knowledge in this field mainly due to the need of a proper modelling of sustainability issues and factors to be taken into account. The aim of this paper is mainly to underline the state of the art from a forming point of view about the sustainability contributions offered in any phase of a product life cycle. Actually, a lack in terms of comprehensive contributions is present in the technical literature, thus, the authors try to give a sort of holistic visi…
Efficiency of Split-Way CVT's. A simplified model
2007
ABSTRACT In this paper, a general formula is obtained for the efficiency of all types of Split-Way CVT, consisting of one or two epicyclic trains, a number of fixed ratio gears and one variable speed unit (CVU). It is based on the application of the principle of virtual works and on the simplifying hypothesis that all the dissipation is lumped inside the CVU. The comparison with some experimental results from the literature shows a surprisingly good fit, also in the neighbourhoods of zero speed ratio. INTRODUCTION The possibility of changing the speed ratio continuously between the primary and the secondary shaft of a mechanical transmission is a very interesting topic, mainly in the automo…
Octane Rating of Natural Gas-Gasoline Mixtures on CFR Engine
2014
In the last years new and stricter pollutant emission regulations together with raised cost of conventional fuels resulted in an increased use of gaseous fuels, such as Natural Gas (NG) or Liquefied Petroleum Gas (LPG), for passenger vehicles. Bi-fuel engines represent a transition phase product, allowing to run either with gasoline or with gas, and for this reason are equipped with two separate injection systems. When operating at high loads with gasoline, however, these engines require rich mixtures and retarded combustions in order to prevent from dangerous knocking phenomena: this causes high hydrocarbon (HC) and carbon monoxide (CO) emissions together with high fuel consumption. With t…
Studies Energy Efficiency of the Renewable Sources use Considering Climate in Latvia
2015
AbstractThe paper discusses problems of energy supply of buildings using renewable sources given the local climatic conditions. The meteorological conditions in Latvia and Riga for last year were analyzed. In paper shows examples of energy efficient buildings allowing that to provide comfort temperature and indoor air quality. The structure and composition of local building materials, providing good thermal insulation are described. The heating systems for test buildings using renewable energy sources were investigated. The assessment of the energy efficiency of the “air-air” and “air-water” heat pumps is studied.
Supercharging the Double-Fueled Spark Ignition Engine: Performance and Efficiency
2017
Internal combustion engine development focuses mainly on two aspects: fuel economy improvement and pollutant emissions reduction. As a consequence, light duty spark ignition (SI) engines have become smaller, supercharged, and equipped with direct injection and advanced valve train control systems. The use of alternative fuels, such as natural gas (NG) and liquefied petroleum gas (LPG), thanks to their lower cost and environmental impact, widely spread in the automotive market, above all in bifuel vehicles, whose spark ignited engines may run either with gasoline or with gaseous fuel. The authors in previous works experimentally tested the strong engine efficiency increment and pollutant emi…
Power tracking with maximum efficiency for wireless charging of E-bikes
2014
Wireless charging techniques, based on Inductive Power Transfer (IPT), are attractive for Electric Vehicles (EV), due to benefits such as convenience and safety. An accurate valuation of the maximum achievable efficiency in an IPT system is extremely unlikely due to the high sensitivity to parasitic elements variations. Therefore, an “on site” procedure of power efficiency characterization is useful to get a precise description of the efficiency curve and obtain the actual maximum efficiency. In this paper, a power tracking algorithm aiming at efficiency maximization is proposed for a Wireless Charging system. The algorithm aims at finding the maximum power transfer efficiency with respect …
A Refined Model for Knock Onset Prediction in Spark Ignition Engines Fueled With Mixtures of Gasoline and Propane
2015
In the last decade, gaseous fuels, such as liquefied petroleum gas (LPG) and natural gas (NG), widely spread in many countries, thanks to their prerogative of low cost and reduced environmental impact. Hence, bi-fuel engines, which allow to run either with gasoline or with gas (LPG or NG), became very popular. Moreover, as experimentally demonstrated by the authors in the previous works, these engines may also be fueled by a mixture of gasoline and gas, which, due to the high knock resistance of gas, allow to use stoichiometric mixtures also at full load, thus drastically improving engine efficiency and pollutant emissions with respect to pure gasoline operation without noticeable power los…
A comprehensive tool for efficient design and operation of polygeneration-based energy μgrids serving a cluster of buildings. Part I: Description of …
2013
Polygeneration systems with thermal energy storage represent promising solutions to achieve energy saving and emissions reduction in the civil sector. The definition of customer-oriented design and operation strategies represents a most challenging task, in order to maximize the profitability and make the investment attractive. A large potential is often recognized for the installation of centralized plants serving a cluster of buildings located over a small area; in such cases the design problem becomes extremely complex and the analyst needs reliable instruments to identify the optimal solution. This paper in two parts presents a scientific tool for the optimization of design and operatio…
Simulation model of a molten carbonate fuel cellemicroturbine hybrid system
2011
A Hybrid System based on High Temperature Fuel Cells coupled to a Microturbine allows a high efficiency, low environmental pollution and it may be exploited as a CHP System producing heat and electricity both Grid Connected and Stand Alone; the overall electrical efficiency could reach a very high value (up to 60%) and total efficiency could be over 70% including the contribution due to heat recovery. In the context of wide research activities of ENEA on High Temperature Fuel Cells and Hybrid Systems e that involve materials, system BoP and fuels e a very great effort has been devoted to design and build, in the ENEA Research Centre of “Casaccia”, an experimental Test-Rig based on a Molten …
Higher PV Module Efficiency by a Novel CBS Bypass
2011
There is an increasing focus on reducing costs and improving efficiency for photovoltaic (PV) cells and modules as well as finding a more efficient approach to the product manufacturing. This letter introduces an innovative solution to bypass shaded PV cells instead of a traditional Schottky diode, in order to avoid overheating of cells in the case of partial shading. The goal is to reduce the power dissipation and improve the general efficiency of a PV generator. A novel device called cool bypass switch is then presented. It is made up of a Power MOS driven by a controller with the task to charge a storage capacitor. Tests and comparisons with standard Schottky diodes are then performed an…