Controlling an Electric Turbo Compound System for Exhaust Gas Energy Recovery in a Diesel Engine

Algrain, Marcelo C.

doi:10.1109/eit.2005.1627004

Cited by 22 publications

(20 citation statements)

References 3 publications

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“…The electrical machine can assist engine transients [1][2][3][4][5][6][7] and generate usable energy from the exhaust waste heat [8][9][10]. This system consists in a standard turbocharger with an electric motor/generator mounted within the bearing housing.…”

Section: Introductionmentioning

confidence: 99%

Mild Hybridization via Electrification of the Air System: Electrically Assisted and Variable Geometry Turbocharging Impact on an Off-Road Diesel Engine

Terdich¹,

Martinez-Botas²,

Romagnoli

et al. 2013

Journal of Engineering for Gas Turbines and Power

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Electric turbocharger assistance consists in incorporating an electric motor/generator within the turbocharger bearing housing to form a mild hybrid system without altering other mechanical parts of the engine. This makes it an ideal and economical short-tomedium-term solution for the reduction of CO2 emissions. The scope of the paper is to assess the improvements in engine energy efficiency and transient response correlated to the hybridization of the air system. To achieve this, an electrically assisted turbocharger with a variable geometry turbine has been compared to a similar, not hybridized system over step changes of engine load. The variable geometry turbine has been controlled to provide different levels of initial boost, including one optimized for efficiency, and to change its flow capacity during the transient. The engine modeled is a 7-liter, 6-cylinder diesel engine with a power output of over 200 kW and a sub-JO-kW turbocharger electric assistance power. To improve the accuracy of the model, the turbocharger turbine has been experimentally characterized by means of a unique testing facility available at Imperial College and the data has been extrapolated by means of a turbine meanline model. Optimization of the engine boost to minimize pumping losses has shown a reduction in brake-speciflc fuel consumption up to 4.2%. By applying electric turbocharger assistance, it has been possible to recover the loss in engine transient response of the efficiency-optimized system, as it causes a reduction in engine speed drop of71%-86% and of79%-94% in engine speed recovery time. When electric assistance is present in the turbocharger, actuating the turbine vanes to assist transient response has not produced the desired result but only a decrement in energy efficiency. If the variable geometry turbine is opened during transients, an improvement in specific energy efficiency with negligible decrement in engine transient performances has been achieved.Previous studies have shown that the electric turbocharger assist (ETA) can improve energy efficiency through different mechanisms. These can be divided into the following categories:(1) direct-energy efficiency increase directly correlated to the implementation of the device The electrical machine can be operated in steady state (turbocompounding), which allows a greater fraction of the exhaust waste heat to be recuperated. This extra electrical energy can be fed to the vehicle electrical system and therefore permits the removal or deactivation of alternators [8]. In a fully hybrid configuration, this energy can be used to power an electric motor connected to the engine crankshaft, obtaining a larger reduction in fuel consumption [9,10].(2) indirect-boost optimization for steady-state operation Boosting via turbocharging is a method to increase the energy efficiency and power output of engines. The improvement in engine fuel consumption can only be attained if the turbocharger overall efficiency and turbine inlet temperature are sufficiently high [11], which is poss...

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Section: Introductionmentioning

confidence: 99%

Mild Hybridization via Electrification of the Air System: Electrically Assisted and Variable Geometry Turbocharging Impact on an Off-Road Diesel Engine

Terdich¹,

Martinez-Botas²,

Romagnoli

et al. 2013

Journal of Engineering for Gas Turbines and Power

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“…Such an EMG turbocharging configuration has been described by Algrain (2005) with reported improvement in the overall (steady-state) fuel efficiency of the engine of the order of 5-10%. Engine drivability data for both acceleration and driving cycle performance were provided by Millo et al (2006), who simulated the operation of a motor-generator electrically assisted turbocharging system (incorporating an asynchronous EM, DC-DC converter, super capacitors, and control system) for a heavy-duty diesel engine.…”

Section: Electrically Assisted Turbochargingmentioning

confidence: 99%

Review of Some Methods for Improving Transient Response in Automotive Diesel Engines through Various Turbocharging Configurations

Giakoumis

2016

Front. Mech. Eng.

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Turbocharged diesel engines suffer from worse transient performance than their naturally aspirated counterparts, mostly at low loads and speeds. This leads to overshoot in engine-out exhaust emissions (primarily particulate matter/soot and NOx) after a speed or load increase, as well as poor drivability. The main cause for this problematic behavior is located in the turbocharger in the form of high moment of inertia and unfavorable aerodynamic-type compressor flow characteristics. In the present work, various alternative turbocharging configurations are reviewed that have proven successful in improving the dynamic diesel engine operation. These configurations are combined supercharging, variable-geometry turbine, electrically assisted turbocharging, two-stage series and sequential turbocharging, and lower turbine moment of inertia. Significant improvement in the engine's transient response can be realized when designing for smaller turbocharger frames or applying more than one units (in series or parallel arrangement). Increasing the available turbine torque (e.g., through elevated turbine back pressure in a variable-geometry turbine) is another successful option, as well as enhancement of the boost pressure (e.g., through the use of a positive displacement compressor upstream of the turbocharger). Finally, the use of external energy (e.g., in the form of electrical assistance on the turbocharger shaft during the critical turbocharger-lag phase) is another recently developed and highly promising measure to mitigate the drawbacks of the poor transient performance of turbocharged diesel-engined vehicles and limit their exhaust emissions. The choice of the "best" configuration for a specific application depends on many parameters, such as cost, matching procedure, control system, and mainly type of engine and drive cycle of the vehicle.

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“…Among the different waste heat recovery technologies such as turbocharger [5], Rankine cycle [4,6] and electric turbocompound system [7][8][9], thermoelectric generator (TEG) for direct conversion of vehicle engine waste heat to electricity is becoming noticeable, because it has the merits of no moving part, quiet operation, compact design, high durability and zero emission [10]. It has been demonstrated that thermoelectric materials with figure of merits of about 1.5 could achieve energy conversion efficiencies of about 5-15% [11].…”

Section: Introductionmentioning

confidence: 99%

Effect of vehicle driving conditions on the performance of thermoelectric generator

Diao

et al. 2015

Energy Conversion and Management

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Controlling an Electric Turbo Compound System for Exhaust Gas Energy Recovery in a Diesel Engine

Cited by 22 publications

References 3 publications

Mild Hybridization via Electrification of the Air System: Electrically Assisted and Variable Geometry Turbocharging Impact on an Off-Road Diesel Engine

Mild Hybridization via Electrification of the Air System: Electrically Assisted and Variable Geometry Turbocharging Impact on an Off-Road Diesel Engine

Review of Some Methods for Improving Transient Response in Automotive Diesel Engines through Various Turbocharging Configurations

Effect of vehicle driving conditions on the performance of thermoelectric generator

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