A Model Predictive Controller for the Cooling System of Internal Combustion Engines

Abstract The paper presents some results of the Model Predictive Controller (MPC) methodology applied to the case of the cooling system of an Internal Combustion Engine. To this end, a small spark ignition engine, about 1.2 dm3 displacement volume, is equipped with an electric pump, which is actuated by the controller, independently of engine speed. The goal of the proposed control is to achieve a faster engine warm-up and an effective engine cooling with a much lower coolant flow rate than the one usually adopted, by bringing the cooling system to operate around the onset of nucleate boiling. The developed Model Predictive Control application makes use of a lumped-parameter model, which predicts the heat transfer both in the case of a single-phase forced convection condition and in the presence of nucleate boiling. The performance of the proposed controller is evaluated during the city driving part of the NEDC homologation cycle, which was replicated at the engine test rig. The results show that the proposed controller is robust in terms of disturbance rejection and is effective in reducing warm-up time

A Novel Approach to the Thermal Management of Internal Combustion Engines

Abstract The paper presents a novel control architecture developed with the aim to satisfy the requirements of the cooling system of an ICE, by means of an electric pump and of an ad-hoc developed control module. The developed controller is based on the Robust Model Predictive Control and is designed with the purpose to satisfy the input and output constraints and to reject the external disturbances, by adopting a lumped parameter model of the engine cooling system, which predicts the coolant temperature, the average wall temperature and the heat transfer regime including nucleate boiling. Given that the proposed methodology is valid for each condition, in the present paper the focus is on the engine operating under fully warmed conditions, with the aim to keep the wall temperature into the prescribed limits, with the lowest possible coolant flow rates. This goal is achieved by properly defining the controller parameters. Different control strategies are proposed and their effectiveness is evaluated in terms of engine wall temperature, coolant temperature, coolant flow rate and heat transfer regime in response to step-wise variations in fuel flow rate. The region of stability of the controller is also discussed. Results show that the control algorithm is robust in terms of disturbance rejections and ensures effective and safe cooling with much lower coolant flow rates if compared to the ones provided by the use of the standard crankshaft driven pump

Analysis of a Trigeneration Plant under Transient Operating Conditions

Abstract A dynamic lumped-parameters model has been developed in order to analyse the performance of a combined cooling, heating and power (CCHP) plant during transient load variations. The plant allows the waste heat recovery from four Internal Combustion Engines (ICEs) to produce simultaneously refrigeration power for an absorption chiller, hot water for thermal user and electrical power. The heat recovery is realized through the exhaust gases, the jacket cooling water and the lubricant. The plant includes an auxiliary boiler, which maintains the water temperature levels to the values required by the absorption chiller, and a dry-cooler, which refrigerates the plant water before entering the internal combustion engines. Moreover, a three-way valve, which controls the water flow rate in order to satisfy both the refrigeration and the thermal loads, is considered. The simulations are carried out under thermal-drive and electric-drive strategy and the evaluation of the performance and time response of the CCHP apparatus are presented

Experimental Investigation and Lumped-parameter Model of the Cooling System of an ICE under Nucleate Boiling Conditions

Abstract The work presents the results of experimental tests, which were carried out on a small-displacement spark ignition engine, where a low flow rate electric pump was used to substitute the standard crankshaft-driven one. The engine was then operated both under usual single-phase heat transfer regime and under nucleate boiling conditions. The engine was properly instrumented in order to record coolant pressure, temperature and flow rate as well as metal temperatures. The experimental investigation was coupled with the development of a dynamic lump-parameter model of the engine cooling system. The model calculates the spatial averaged metal temperature, the engine-out coolant temperature and the fraction of metal heat transfer area which is involved in nucleate boiling as a function of engine-in coolant flow rate, pressure and temperature, fuel mass flow rate and engine speed. The experimental data and the model results show a good agreement and the model is suitable to develop a coolant flow rate control system. This facilitates faster engine warm-up, lower fuel consumption and lower CO 2 emissions, which can be significant under low-load and cold-start conditions

Design and analysis of a new wave energy converter based on a point absorber and a hydraulic system harvesting energy from waves near the shore in calm seas

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cfd investigation of the open center on the performance of a tidal current turbine

In the present paper, a revision of the layout of an innovative open center self-balancing tidal turbine is presented. Initially, the design was characterized by a central deflector, responsible fo ..

hydraulic on shore system recovering energy from sea waves

Abstract The authors propose a new system for recovering energy from sea waves. The system is composed of a large-sized buoy (point absorber), directly connected to a piston pump. The piping, developed underground, allows the water to be moved into a pressurized reservoir, which feeds a hydraulic turbine. The latter discharges the flow in a tank where the hydraulic circuit closes. A sizing methodology developed in the present work, demonstrates the possibility of designing miniaturized components by leaving the possibility of providing an acceptable energy output with low installation costs. A preliminary study demonstrates that a 4.5 m buoy, associated with a small 17 cm diameter Pelton, could be able to recover more than 35,000 kWh/year

Design and Numerical Analysis of a Double Rotor Turbine Prototype Operating in Tidal Currents

Abstract This work shows the results of a study carried out for several years by the Department of Mechanical, Energy and Management Engineering (DIMEG), in collaboration with SintEnergy Srl. The aim was to develop an innovative marine turbine, taking advantagesfrom the tidal currents. The turbine, which is made-up of two concentric contra-rotating rotors, has been designed to operate anchored to the coast without any supporting structures on the seabed. An iterative procedure, based on a zero-dimensional approach, was developed for the estimation of blades dimensions as well as the rotors performances in terms of lift, drag, power coefficient and efficiency. In order to validate the results of the design procedure, numerical simulations based on three-dimensional analysis were also carried out. The three dimensional study was carried out using the commercial code FLUENT, which follows the Reynolds Averaged Navier-Stokes (RANS) approach, in conjunction with the two-equation Realizable k- ɛ turbulence model

Computational Fluid Dynamic Analysis of the External Rotor Supporting the Design of a Tidal Kinetic Turbine Prototype

The purpose of this paper is to ascertain the reliability of a zero-dimensional approach, aimed to design a double rotor kinetic turbine prototype, by means of computational fluid dynamic analysis. The interaction between the flow and the blade of the turbine prototype external rotor is evaluated. The calculation is carried out by a three-dimensional analysis using the commercial code FLUENT 15.0. In the present work, the Reynolds Averaged Navier-Stokes approach is used, with the two-equation Realizable k-epsilon turbulence model. The blades profile is a NACA 4412 interacting with flow at an attack angle of 4°, which is kept constant along the blade height. The estimation of the forces acting on the blades allows a more accurate evaluation of the blade lift coefficient, which is useful to design the blades geometry and to compute the power coefficient, previously estimated by the traditional mono-dimensional approach

Effects of high intensity interval training on neuro-cardiovascular dynamic changes and mitochondrial dysfunction induced by high-fat diet in rats

This research was supported by the Brazilian National Council for Scientific and Technologic Development (CNPq) (Grant number: 474116/2008-5) and Carlos Chagas Filho Foundation for Research Support in the State of Rio de Janeiro (FAPERJ) (Grant number: E-26/ 111.732/2011), both received by Eliete Bouskela. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewedPublisher PD