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In this paper, starting from the measurements available for a 2000 cm3 turbocharged diesel engine, an analytical model of the turbocharger is proposed and validated. The model is then used to extrapolate the efficiency of a power unit with a diesel engine combined with a turbocompound system. The obtained efficiency map is used to evaluate the fuel economy of a supercapacitor-based series hybrid vehicle equipped with the turbocompound power unit. The turbocompound model, in accordance with the studies available in the technical literature, shows that the advantages (in terms of efficiency increase) are significant at high loads. For this reason, turbocompound introduction allows a significant efficiency improvement in a series hybrid vehicle, where the engine always works at high-load. The fuel economy of the proposed vehicle is compared with other hybrid and conventional vehicle configurations.

Pure electric mobility is still struggling to emerge in the present road vehicles scenario. This is mostly due to costs, nowadays still very high, and to battery range, which is intrinsically very limited with respect to the fuel tank of a traditional vehicle. To be effectively competitive, e-mobility should not be thought as the mere substitution of the thermal powertrain with the electric one on the same vehicle; instead, a holistic approach comprehensive of the integration of a charging network within the territory should be adopted. The vehicles should be tailored on the missions to be accomplished promoting the lightness, simplicity and low cost, and should be integrated within a charging infrastructure and a car-sharing system implemented in the reference territory. In this paper the authors aim at exposing their idea of e-mobility, justifying it by simulations carried out on three different vehicles (a Diesel-fuelled Renault Kangoo, an electric driven Renault Kangoo and an electric micro-vehicle Renault Twizy) and experimental data. The simulations were carried out with the help of a validated road vehicle model in different real road missions, namely a urban, an extra-urban and a mountain mission.

The improvement of renewable energy sources exploitation is a central topic of the present studies in the energetic field. One of the main obstacles to the renewable energy increase in the global energetic mix is represented by the fluctuating nature of renewable power sources. The power fluctuations are cause of stress for the electric grid to which the individual nodes are connected. A wider exploitation of renewable power is possible through the implementation of a “smart grid”, constituted by an interconnection of several smart nodes consisting in a user and a renewable source. To reduce the stochastic effects of the renewable energy source it is possible to introduce in the nodes composing the smart grid an energy storage, finalized to smooth the power peaks, rending the node itself less disturbing for the electric grid. This paper presents a simulation model of a smart node, consisting in a user power profile, a photovoltaic panel, an electric vehicle and a battery. Through the simulation model it is possible to evaluate the node effect on the electric grid, with a quantitative approach. Tests were worked out in different node configurations: basic (the only user power profile), basic with photovoltaic panel, basic with storage, basic with panel and storage and finally the complete configuration including also the electric vehicle. The tests were repeated for a domestic and an industrial user to evaluate the size influence over the parameters of interest.

The present paper aims to propose an original steam generation system, which resulted suitable for the application to the secondary loops of lead-cooled fast reactors: reaction heat is extracted from the lead by means of a coolant under vapor phase, thanks to both an external feed-water boiling and special bayonet tubes in the primary–secondary fluid heat exchangers. The performance of three different steam cycles equipped with this system were evaluated for the secondary loop of ALFRED 300 MW th demonstrator. The bayonet heat exchangers were sized through a coordinated interaction between a 1D finite-difference mathematical model and an automated size optimization process. A structural analysis of the circular plate supporting the bayonets was performed through the ANSYS 11 solver. The proposed steam cycles, 40 bar with superheating, 80 bar with live steam re-heating and 80 bar with double-superheating, show efficiency values of respectively 34%, 40% and 41%. A performance comparison with other cycles proposed in literature is provided. This solution is expected to provide significant safety advantages, for the secondary fluid low pressure and the gaseous flow in the heat exchangers, still keeping satisfactory efficiency values.

A vehicular powertrain can be thought as an energy conversion chain, each component being characterized by its efficiency. Significant global efficiency improvements can be achieved once is identified the system energy breakdown, individuating the losses connected to each powertrain component; it is then possible to carry out the most appropriate interventions. This paper presents a simulation study of a diesel-fuelled commercial vehicle powertrain based on the above summarized point of view. The work aims at individuating the energy flows involved in the system during different missions, proposing an intelligent combination of technical solutions which minimize fuel consumption. Through a validated Matlab–Simulink model, able to indicate the powertrain energy breakdown, simulations are carried out to evaluate the fuel saving associated to a series of powertrain management logics which lead to the minimization of engine losses, the recovery of reverse power in deceleration and braking, the elimination of useless engine cycles. Tests were performed for different real missions (urban, extra-urban and highway). The results obtained point out a –23% fuel consumption (average value for urban, extra-urban and highway missions) compared to the traditional powertrain. Clearly, such result affects positively the CO 2 emission.

The present paper is centred on the design of a bayonet tube steam generator, fundamental part of an innovative lead-cooled fast nuclear reactor (LFR). The construction of the LFR is the main objective of the European project named LEADER, of which Ansaldo Nucleare is an important member. The steam generator described in this paper is expected to be installed in a 300 MW thermal power demonstrator plant, named ALFRED. The investigations carried out in this work through the RELAP 5 code have first faced the sizing of the single bayonet tube and then the design of the whole heat exchanger. The configurations of the four coaxial tubes composing the single bayonet, the length of the bayonets and the materials employed have been investigated; the final heat exchanger configuration provides 510 bayonet tubes of 6 m active length with a thermal insulation between the inner descending tube and the rising annulus, assured by a special extremely insulating paint. The whole steam generator has shown its capability to reach the required exchanged power of 37.5 MWth, providing as output dry superheated steam at the desired temperature of 450 °C.

Combined Heat and Power based District Heating Networks (CHP/DHN) systems represent nowadays one of the most efficient technologies, as an alternative to standard space heating solutions, leading to lower GHG emission in atmosphere. Dynamic modelling of district heating networks is of considerable importance in order to investigate suitable control strategies aimed to optimize the heat production and to manage the system transients following changes in the required heat. Through the analogous electrical systems modelling approach, a component software library has been developed for icon-based dynamic simulation of district heating networks, implementing the mathematical models in Matlab/Simulink environment. The calculation procedure that translates into practice the approach described above, complies with a main flow chart designed to allow for the simulation of the system operation in a quicker-than-real time, throughout the controlled time interval, while imposing the assumed duty and site conditions. The procedure’s main body, as well as being utilized to assess the feasibility and to carry out the conceptual design, once the plant has started up, can be employed as a guide to the operator. Research activity has been focused on the development and integration of a code for dynamic simulation of heat distribution networks with a code for thermo-economics optimization of CHP systems, increasing the possibility of optimizing the matching between CHP plant and thermal users, through the exploitation of thermal storage capacity of the networks. A CHP-based district heating project in Northern Italy was considered as a test case. Results show that integrated management of cogeneration plants and district heating networks allows for the achievement of significant advantages both in terms of economic competitiveness and energy saving: in particular it has been highlighted that only through the support of an intelligent management system it is possible to maximize the potential benefits offered by the exploitation of district heating networks dynamic heat storage capacity.

The generation IV lead cooled fast reactors are of particular interest for the Italian research. At present, one significant European project in progress is LEADER (Lead cooled European Advanced DEmonstrator Reactor) which includes, among its goals, the construction of a lead-cooled fast reactor demonstrator, ALFRED (Advanced Lead Fast Reactor European Demonstrator). The demonstrator provides technical solutions that simplify the construction phase and assure full safety in operation; according to the latest guidelines, ALFRED final configuration will be characterized by a secondary loop providing bayonet-tube steam generators. In a previous paper, the Authors proposed the EBBSG (External Boiling Bayonet Steam Generator) system, in which the reaction heat is extracted from the lead by means of coolant under vapor phase. In the present paper, the Authors propose a decay heat removal (DHR) system to match the EBBSG scheme. The DHR system is fully passive, exploiting natural circulation phenomena. The performance of the system is investigated through a Matlab–Simulink model. The results are satisfactory since, according to simulations, the proposed DHR system is able to keep the primary coolant temperature within a safety range for a sufficient time, avoiding the lead freezing or over-heating.

In countries where space heating demand is limited to a few months in the year, potentials for increasing the penetration of cogeneration (CHP) are strictly linked to sites where concentrated heat utilizations already exist. Hence the energy system will move towards a larger number of small-medium size CHP plants, which is herein named distributed cogeneration. Design criteria are analysed for plants in this context, from a technical and economical standpoint. A case study is reported, focused on the most suitable heat to work ratio. It is found that the pricing and tax systems, as they are stated by the domestic legislation, push the design point and the operating conditions yielding the best economy, into a range where CO2 emissions are remarkably higher than the least possible.

The generation IV lead cooled fast reactors are of particular interest for the Italian research: several influential companies (Ansaldo Nucleare, ENEA) are involved in these important European R&D projects. At present, one significant European project in progress is LEADER (Lead cooled European Advanced DEmonstrator Reactor) which includes, among its goals, the construction of a lead-cooled fast reactor demonstrator, ALFRED (Advanced Lead Fast Reactor European Demonstrator). The demonstrator has to include technical solutions that simplify the construction phase and assure full safety in operation; according to the latest guidelines, ALFRED final configuration will be characterized by a secondary loop providing bayonet-tube steam generators. The Authors have addressed the issue of bayonet-tube steam generators proposing the EBBSG (External Boiling Bayonet Steam Generator) system, in which the reaction heat is extracted from the lead by means of coolant under vapor phase. This is possible thanks to an external feed-water boiling, based on the known Loeffler scheme, coupled to the bayonet tube concept. In the present paper, the Authors propose a decay heat removal (DHR) system to match the EBBSG scheme. The DHR system is fully passive, exploiting natural circulation phenomena. The performance of the proposed DHR system is investigated through a Matlab-Simulink model. The results are satisfactory since, according to the simulations, the proposed DHR system is able to keep the primary coolant temperature within a safety range for a sufficient time, avoiding the lead freezing or over-heating.

The Integrated Project EUROTRANS, funded by the European Commission as part of the 6th European framework program, provides the advanced design of a multi purpose research oriented Accelerator Driven System (ADS), called XT-ADS (eXperimenTal-ADS), and the preliminary design of an industrial scale ADS, called EFIT (European Facility for Industrial Transmutation) [1]. EFIT [2] [3] is fuelled with Minor Actinides (U-free fuel) and its main design options overcome the limits of previous ADS projects, particularly as concerns the economic aspects, maintaining meanwhile the high safety level, the high reliability and low investment risks. EFIT is endowed with three different systems to remove decay heat, this paper deals with the Decay Heat Removal System 2 (DHR2). DHR2 mainly consists of an isolation condenser (IC) connected to the secondary side of the Steam Generators (SGs). DHR2 is a passive safety system: system operation is based on condensation of the steam coming from the SG unit and gravity head injection of the condensate back to the SG inlet. The system has been designed to satisfy the following two requirements: • to evacuate the decay power maintaining acceptable values of the vessel and fuel temperature; • to avoid lead solidification also in the configuration of maximum efficiency.Copyright © 2009 by ASME

Renewable energy sources, presently constituting about 23% of the total Italian power production, are featured by very discontinuous supply during the day that, to avoid grid malfunctions, must be compensated by fossil fuelled power plants. The latter must hence be able to rapidly control power supply. This paper proposes a power regulation system for coal power plants, consisting in the bypass of the low pressure pre-heaters in order to increase the steam flow-rate in turbine. The main advantage of this system is the limited thermo-mechanical stress induced in the pre-heaters. The solution effectiveness is investigated through a Matlab-Simulink model.

This paper presents the simulation activity carried out to analyze the power flows and the energy breakdown of an innovative hybrid-turbocompound powertrain, which will be employed in the 2014 F1 championship. The analyzed powertrain consists in a supercharged internal combustion engine integrated by two electric machines – connected respectively to the turbocharger shaft and to the engine shaft – a static converter and a battery. Simulations through Matlab-Simulink were carried out both in race and in qualifying conditions, obtaining useful information about the electric machines and battery duty cycles and about the calibration of the system operational algorithms during one lap.