Thermal Management of Electrified Vehicles—A Review

Vehicle electrification demands a deep analysis of the thermal problems in order to increase vehicle efficiency and battery life and performance. An efficient thermal management of an electrified vehicle has to involve every system of the vehicle. However, it is not sufficient to optimize the thermal behavior of each subsystem, but thermal management has to be considered at system level to optimize the global performance of the vehicle. The present paper provides an organic review of the current aspects of thermal management from a system engineering perspective. Starting from the definition of the requirements and targets of the thermal management system, each vehicle subsystem is analyzed and related to the whole system. In this framework, problems referring to modeling, simulation and optimization are considered and discussed. The current technological challenges and developments in thermal management are highlighted at vehicle and component levels

A Method to Obtain a Maxwell–Boltzmann Neutron Spectrum at kT = 30 keV for Nuclear Astrophysics Studies

AbstractA method to shape the neutron energy spectrum at low-energy accelerators is proposed by modification of the initial proton energy distribution. A first application to the superconductive RFQ of the SPES project at Laboratori Nazionali di Legnaro is investigated for the production of a Maxwell–Boltzmann neutron spectrum at kT = 30 keV via the 7Li(p, n)7Be reaction. Concept, solutions and calculations for a setup consisting of a proton energy shaper and a lithium target are presented. It is found that a power dentisity of 3 kW cm−2 could be sustained by the lithium target and a forward-directed neutron flux higher than 1010 s−1 at the sample position could be obtained. In the framework of the SPES project the construction of a LEgnaro NeutrOn Source (LENOS) for Astrophysics and for validation of integral nuclear data is proposed, suited for activation studies on stable and unstable isotopes

Eco-Driving Strategy Implementation for Ultra-Efficient Lightweight Electric Vehicles in Realistic Driving Scenarios

This paper aims to provide a quantitative assessment of the effect of driver action and road traffic conditions in the real implementation of eco-driving strategies. The study specifically refers to an ultra-efficient battery-powered electric vehicle designed for energy-efficiency competitions. The method is based on the definition of digital twins of vehicle and driving scenario. The models are used in a driving simulator to accurately evaluate the power demand. The vehicle digital twin is built in a co-simulation environment between VI-CarRealTime and Simulink. A digital twin of the Brooklands Circuit (UK) is created leveraging the software RoadRunner. After validation with actual telemetry acquisitions, the model is employed offline to find the optimal driving strategy, namely, the optimal input throttle profile, which minimizes the energy consumption over an entire lap. The obtained reference driving strategy is used during real-time driving sessions at the dynamic driving simulator installed at Politecnico di Milano (DriSMi) to include the effects of human driver and road traffic conditions. Results assess that, in a realistic driving scenario, the energy demand could increase more than 20% with respect to the theoretical value. Such a reduction in performance can be mitigated by adopting eco-driving assistance systems

Isotopic Composition of Fragments in Nuclear Multifragmentation

The isotope yields of fragments, produced in the decay of the quasiprojectile in Au+Au peripheral collisions at 35 MeV/nucleon and those coming from the disassembly of the unique source formed in Xe+Cu central reactions at 30 MeV/nucleon, were measured. We show that the relative yields of neutron-rich isotopes increase with the excitation energy in multifragmentation reaction. In the framework of the statistical multifragmentation model which fairly well reproduces the experimental observables, this behaviour can be explained by increasing N/Z ratio of hot primary fragments, that corresponds to the statistical evolution of the decay mechanism with the excitation energy: from a compound-like decay to complete multifragmentation.Comment: 10 pages. 4 Postscript figures. Submitted to Physical Review C, Rapid Communicatio

Roundabouts: Traffic Simulations of Connected and Automated Vehicles—A State of the Art

The paper deals with traffic simulation within roundabouts when both “connected and automated vehicles” (CAVs) and human-driven cars are present. The aim is to present the past, current and future research on CAVs running into roundabouts within the Cooperative, Connected and Automated Mobility (CCAM) framework. Both microscopic traffic simulations and virtual reality simulations by dynamic driving simulators will be considered. The paper is divided into five parts. At first, the literature is analysed using the Systematic Literature Review (SLR) methodology based on Scopus database. Secondly, the influence of CAVs on roundabout-specific design features and configuration is analysed. Gap-acceptance models used to define the capacity of the roundabout, one of its most important key performance indicators, are also presented. Third, the most common simulation software are described and analysed in terms of traffic demand implementation. Then the communication approaches and path management algorithms are studied. An example is proposed on the integration of microscopic traffic simulations and dynamic driving simulators virtual reality simulations. Finally, car following models suitable for roundabout traffic are discussed. There is still a gap between simulations and actual experience. There are reasonable doubts on how modelling and optimizing CAVs’ behaviour into roundabouts in view of CCAM. It seems that Cooperative, Connected and Automated Vehicles (CCAVs), more than simply Connected and Automated Vehicles (CAVs), could optimise traffic flow, safety and driving comfort within the roundabout. A very promising technology for traffic simulation within the roundabout seems the one based on dynamic driving simulators

Multi-Disciplinary Optimisation of Road Vehicle Chassis Subsystems

Two vehicle chassis design tasks were solved by decomposition-based multi-disciplinary optimisation (MDO) methods, namely collaborative optimisation (CO) and analytical target cascading (ATC). A passive suspension system was optimised by applying both CO and ATC. Multiple parameters of the spring and damper were selected as design variables. The discomfort, road holding, and total mass of the spring–damper combination were the objective functions. An electric vehicle (EV) powertrain design problem was considered as the second test case. Energy consumption and gradeability were optimised by including the design of the electric motor and the battery pack layout. The standard single-level all-in-one (AiO) multi-objective optimisation method was compared with ATC and CO methods. AiO methods showed some limitations in terms of efficiency and accuracy. ATC proved to be the best choice for the design problems presented in this paper, since it provided solutions with good accuracy in a very efficient way. The proposed investigation on MDO methods can be useful for designers, to choose the proper optimisation approach, while solving complex vehicle design problems

The SPES project: a second generation ISOL facility

Abstract SPES is an INFN project to develop a Radioactive Ion Beam facility as an intermediate step toward EURISOL, the next generation European ISOL facility. The facility will be installed at the Laboratori Nazionali di Legnaro where the superconductive linac ALPI will reaccelerate the exotic beams at energies larger than 10 AMeV. Neutron-rich radioactive beams will be produced by proton-induced Uranium fission at an expected in-target fission rate of 1013 fissions per second. As proton driver, a 70 MeV cyclotron with a total current of 0.750 mA shared on two exit ports will be installed. The key feature of SPES is to provide high intensity and high-quality beams of neutron-rich nuclei to perform forefront research in nuclear physics as well as to develop and interdisciplinary research center based on the cyclotron proton beam. Neutron production at a rate of 1014 n/s is expected using the proton beam on thick target. The status of the project and the layout of the neutron facility will be presented. Two facilities can be operated at the same time, with a capability of 5000 h per year each. The ISOL facility will use 0.2 mA to reach the goal of 1013 fissions per second and more than 0.5 mA will be available for applied physics applications, mainly neutron beam and medical isotopes production

Micro-channel–based high specific power lithium target

A micro-channel–based heat sink has been produced and tested. The device has been developed to be used as a Lithium target for the LENOS (Legnaro Neutron Source) facility and for the production of radioisotope. Nevertheless, applications of such device can span on many areas: cooling of electronic devices, diode laser array, automotive applications etc. The target has been tested using a proton beam of 2.8MeV energy and delivering total power shots from 100W to 1500W with beam spots varying from 5mm2 to 19mm2. Since the target has been designed to be used with a thin deposit of lithium and since lithium is a low-melting-point material, we have measured that, for such application, a specific power of about 3kW/cm2 can be delivered to the target, keeping the maximum surface temperature not exceeding 150◦C