Roberto Cipollone

Analysis of the potential performance of a combined hybrid vehicle with optimal supervisory control

The paper presents an optimization analysis of the supervision control strategies of a combined hybrid propulsion system, realized via a direct (i.e., without a planetary gear set) mechanical link between the shaft of the internal combustion engine and the shaft of the traction electric motor. The analysis is based on a quasistatic mathematical model of the overall system that is derived in a pure analytical fashion, using the Willans approach, in order to help the synthesis of the control laws. The latter are calculated using Pontryagins Minimum Principle and the Euler-Lagrange equations of the optimal control theory. Simulation tests performed over a hybridized mass-production van show the potential of the combined-hybrid architecture, in terms of fuel economy, in comparison to the conventional (engine-only), the series-hybrid, and the parallel-hybrid architectures.

A Fully Transient Model For Advanced Engine Thermal Management

ABSTRACT Cooling system design has a crucial role in defining engine performance and operational limits. Many further improvements can be obtained both in the precision in controlling temperatures of the various engine parts (especially during transient operation), and in the energy consumption of the system. Moreover, the warm-up transient can be relevantly reduced producing benefic effects on vehicle emissions and interior conditioning and comfort. Taking the lead by these considerations, the authors developed an integrated model of an engine cooling system, which is characterized by a complete modularity and permits the simulation of any possible design configuration. The model acts as a “virtual engine cooling system”: its coupling with simple ECU models permits an off-line evaluation of the efficiency of new control strategies, model-based too. In this work a novel model for the engine thermal behavior is proposed to be included in the described modeling architecture. The model so makes it possible permit the simulation of fully transient working conditions including those encountered during engine warm-up.

Energy recovery using sliding vane rotary expanders

Energy recovery from low grade energy sources represents a technological challenge which can significantly contribute to the energy balance between production and consumption. Mechanical and electrical production can be done both from thermal energy usually wasted and low temperature renewable sources. In this sense, the interest is twofold. Many efforts have been made and studies produced, mainly making reference to a well known organic Rankine cycle (ORC) of transformations: in spite of this, the expander technology still represents an open aspect and call for a reliable and low cost development.

A/F and Liquid-Phase Control in LPG Injected Spark Ignition ICE

Many advantages are related to the use of LPG as fuel in SI injected ICE. Most of them regard the lower environmental impact with respect to gasoline. The liquid-phase injection is one of the most important aspects of these engines, being able to guarantee the maintenance (and even an increase) of the more traditional engine performances (power, acceleration, driveability, etc) and to match the 3-way catalytic converter A/F specifications. In this paper the transient phenomena occurring in an LPG injection system have been studied, focusing the attention on the problems related to A/F and liquidphase control.

Sliding Vane Rotary Compressor Energy Optimization

The reduction of the electrical energy for producing compressed air gives an important contribution to the overall energy saving in the industrial context. Among the different technologies, Sliding Vane Rotary Compressors (SVRC) demonstrate unforeseen potential in terms of energy saving due to some intrinsic features specifically related to this machine.One of the most important contribution is given by cooling the air during compression; this could be achieved by a proper oil injection conceived for this purpose. A mathematical model describing the oil injection process is presented in this paper. It considers the main parameters which describe the spray formation, its penetration inside the cell till to the intersection with metallic surfaces and the resulting air cooling.The influence of the most important design and operating injection parameters have been checked on the model and design rules are outlined in order to produce an oil injection potentially able to reduce mechanical work.© 2012 ASME

Sliding vane rotary compressor technology and energy saving

Energy saving, CO2 reduction, and energy generation from renewable sources represent the three cornerstones of the energetic and environmental commitments of all the countries in the world. These three elements may give a quantitative contribution to the sustainability in an industrial environment. Among them, the most important one, that represents a driver in many sectors, is the limitation of the CO2 concentration in the atmosphere: most recent data (2013) from National Oceanic and Atmospheric Administration – Earth System Research Laboratory (NOAA-ERSL) set at 395.55 parts per million (ppm) the CO2 in the atmosphere and the continuous increasing trend will quickly allow to reach the 450 ppm level which is considered as a safeguard limit to avoid irreversible environmental and socioeconomics problems. Looking at the energy consumption side, energy saving is a key factor. Compressed air production does not escape this requirement and, for the compressor manufacturing industry, this can represent an opportunity with great potential benefits. Compressed air is produced by electrical energy and the consumption accounts as much as 10% of industrial consumption of electricity. A lower estimate places at 6% this share but an additional 12% is estimated to be associated with the commercial and residential markets (portable tools, air pumps, pneumatic heating, ventilation, air conditioning, etc.). Hence, the overall compressor needs are estimated equal to 20% of the industrial electricity needs. Considering that industrial consumption of electricity represents a given share of the overall electrical energy consumption (it depends on the geographical context, social development, industrial level, etc.), with good approximation, compressed air can be associated to the overall electricity consumption and to primary energy consumption too. So, it can be compared with the other energy alternatives when the data are reliable and referred to real situations, actions to promote energy efficiency in compressed air systems can be identified with their real importance and compared with all the other measures. From many independent studies the most important energy saving measures are associated to the: (1) reduction of leakages on the distribution lines, (2) a more appropriate compressed air system design, (3) use of adjustable speed drives, (4) waste heat recovery. All these aspects, in a 10-year period of operation, weigh 70–75% of the overall compressed air costs. Therefore, the compressor technology is a key factor to reduce energy consumption including in it load control, variable speed operation, compressor sizing, etc. A great potential saving is associated to leaks, friction pipes, etc. but these actions are downstream of the compressed air production. After having discussed some issues concerning the future overall energy consumption and CO2 emissions, considering the development of the electricity market in the world in the near future, and overall energy characteristics of existing machines widely used in the compressed air market, the article goes deep inside a specific compressor technology which is represented by the sliding vanes rotary type. Principal processes inside these machines are discussed in the light of the recent scientific literature advancement of a theoretical and experimental nature. The general idea was that these machines are not so well known and their use is not so widespread: thanks to a deeper scientific interest over the past few years, these compressors had a notable performance improvement, thus a greater potential in industrial applications. Thanks to some intrinsic aspects, some energy issues are presented and related to specific processes inside the machine and compared with other compressors. The potential further improvements in terms of specific energy are discussed and addressed in main future research directions.

Energy saving in sliding vane rotary compressors using pressure swirl oil atomizers

In industrial contexts, electrical energy for compressed air represents an important share of the global electricity consumption: this figure accounts for 4–5% of the total. Among the existing compressor technologies, rotary volumetric machines proved to be more suitable than other types (dynamic, reciprocating, etc.) in terms of pressure and flow rate delivered. Even though not as widespread as screw machines, but thanks to the technological improvements made in the last two decades, sliding vane rotary compressors are characterized by premium specific energy consumptions and demonstrate an unforeseen potential in terms of energy saving due to some intrinsic features specifically related to these machines. The current research focuses on an innovative oil injection technology that is not only able to fulfill the sealing and lubrication requirements but also to cool the air during the compression phase. A comparison between the mathematical model of the new oil injection technology and the experimental p-V diagrams measured through a set of piezoelectric transducers is shown. The compression work reduction, predicted in the model and further measured at the shaft and observed in the indicator diagrams, gives a strong consistency to the injection technology.

Development of an organic Rankine cycle system for exhaust energy recovery in internal combustion engines

Road transportation is currently one of the most influencing sectors for global energy consumptions and CO2 emissions. Nevertheless, more than one third of the fuel energy supplied to internal combustion engines is still rejected to the environment as thermal waste at the exhaust. Therefore, a greater fuel economy might be achieved recovering the energy from exhaust gases and converting it into useful power on board. In the current research activity, an ORC-based energy recovery system was developed and coupled with a diesel engine. The innovative feature of the recovery power unit relies upon the usage of sliding vane rotary machines as pump and expander. After a preliminary exhaust gas mapping, which allowed to assess the magnitude of the thermal power to be recovered, a thermodynamic analysis was carried out to design the ORC system and the sliding vane machines using R236fa as working fluid. An experimental campaign was eventually performed at different operating regimes according to the ESC procedure and investigated the recovery potential of the power unit at design and off-design conditions. Mechanical power recovered ranged from 0.7 kW up to 1.9 kW, with an overall cycle efficiency from 3.8% up to 4.8% respectively. These results candidate sliding vane machines as efficient and reliable devices for waste heat recovery applications.

Vehicle Thermal Management: A Model-Based Approach

Cooling system design has a crucial role in defining engine performance, operational limits and thermal comfort. Many further improvements with respect to the actual situation can be obtained through a more accurate control of an-board thermal needs. To this new interest the definition of new technical specifications must follow. The technical literature, however, seems not fully satisfying this need, not focusing on the influence of these technical specifications on system design, reliability and costs. In this paper the authors present a contribution in this direction, showing the capabilities of an active intelligent management of the engine cooling system. This can be obtained through different control strategies, strongly diversified for their cost-performance ratio. The potentiality of a model-based controller has been also investigated and compared with the correspondent closed-loop controller.Copyright

Gases as Working Fluid in Parabolic Trough CSP Plants

Abstract The energetic dimension of actual economy is massively oriented towards the use of fossil fuels: they cover a share of 87% of the energy needs and the trend of this share is increasing, in spite of the commitments adopted by almost all the Countries in the World. Most crucial concern is CO2 levels in the atmosphere and the positive feedback between Earths temperature increase and carbon. Actual technologies which make use of renewable sources seem to be not fully suitable to invert this continuous increase of fossil fuels. Concentrated Solar Power plants (CSP) have had, recently, a huge attention as a technology able to give, in the mean future, a strong contribution to the electrical energy generation. CSP technology has an intrinsic superiority with respect to the other renewable plants but actual plants suffer of many drawbacks which slow down a massive diffusion: these aspects increase costs and do not insure the reliability levels required to make the investments profitable. Gas as heat transfer fluid inside solar receiver in a CSP Parabolic Trough (PT) type plant is discussed in this paper: this would simplify actual technology in the conversion section, downstream the solar energy collecting phase. The use of gases calls for a new conversion section discussed in this paper based on a direct expansion in gas turbine plants. The success of this concept is related to the possibility to increase the fluid (gas) temperature above the actual operating maximum values. The paper discusses the performances of a new gas cycle, the performances of actual receivers when fed with gas and introduces and discusses an optimization design parameter which allows a cost decrease and industrial reliability improvement.