Modelling and Testing of a Turbo-generator System for Exhaust Gas Energy Recovery

Michon, Melanie; Calverley, S.D.; Clark, Richard E.; Howe, D.; Chambers, Jonathan; Sykes, P.A.; Dickinson, P.G.; McClelland, Mike; Johnstone, G. G.; Quinn, R.; Morris, G.

doi:10.1109/vppc.2007.4544184

Cited by 19 publications

(5 citation statements)

References 2 publications

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“…Moreover, as already mentioned, the exhaust gas turbine employed in a hybrid propulsion system should work under almost steady state conditions, which is why a torque/current control on the generator would allow the machine to operate at its best efficiency speed ratio, regardless of the power produced. The only turbine generator products present on the market or studied until now are composed of a radial turbine for turbocharging applications connected to an electric generator [30][31][32], and are designed exclusively to supply the vehicle's electric accessories, thus producing a very limited power output (i.e., 6 kW). Due to the lack of adequate products both in the literature and on the market, and according to the previous considerations, the authors assumed that in the compound engine, the turbine works with an almost constant speed ratio, regardless of the power produced, and hence with an almost constant efficiency η T .…”

Section: Separated Electric Compound Spark Ignition Enginementioning

confidence: 99%

Efficiency Advantages of the Separated Electric Compound Propulsion System for CNG Hybrid Vehicles

Pipitone

Caltabellotta

2021

Energies

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As is widely known, internal combustion engines are not able to complete the expansion process of the gas inside the cylinder, causing theoretical energy losses in the order of 20%. Several systems and methods have been proposed and implemented to recover the unexpanded gas energy, such as turbocharging, which partially exploits this energy to compress the fresh intake charge, or turbo-mechanical and turbo-electrical compounding, where the amount of unexpanded gas energy not used by the compressor is dedicated to propulsion or is transformed into electric energy. In all of these cases, however, maximum efficiency improvements between 4% and 9% have been achieved. In this work, the authors deal with an alternative propulsion system composed of a CNG-fueled spark ignition engine equipped with a turbine-generator specifically dedicated to unexpanded exhaust gas energy recovery and with a separated electrically driven turbocompressor. The system was conceived specifically for hybrid propulsion architectures, with the electric energy produced by the turbine generator being easily storable in the on-board energy storage system and re-usable for vehicle traction. The proposed separated electric turbo-compound system has not been studied in the scientific literature, nor have its benefits ever been analyzed. In this paper, the performances of the analyzed turbo-compound system are evaluated and compared with a traditional reference turbocharged engine from a hybrid application perspective. It is demonstrated that separated electric compounding has great potential, with promising overall efficiency advantages: fuel consumption reductions of up to 15% are estimated for the same power output level.

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Section: Separated Electric Compound Spark Ignition Enginementioning

confidence: 99%

Efficiency Advantages of the Separated Electric Compound Propulsion System for CNG Hybrid Vehicles

Pipitone

Caltabellotta

2021

Energies

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“…Therefore the bypass valve or emergency braking device installing is recommended. The parallel setting allows controlling the exhaust gas flow through the turbogenerator, controlling the power of the turbogenerator, performing maintenance on the operating unit, operating the power plant with the turbine generator switched off, and, in case of emergency, shutting off the exhaust gas supply to the turbogenerator, thereby reducing possible damage and cost of repairs, and also increasing the efficiency and productivity of the power plant [6][7][8] . This scheme also has a number of disadvantages, such as the increase in cost due to the need for high-temperature mass-size parameters, as well as the increase in the number of shutters, the design complexity and the increase in discharge resistance due to hydraulic losses.…”

Section: Disposition Of a Turbogenerator In The Exhaust Systemmentioning

confidence: 99%

“…A turbogenerator must produce from 5 to 10 kW of electric power with a specific fuel consumption reduction of at least 7% compared to the engine chosen. According to the research conducted, the recovery systems can convert up to 12-15% of the exhaust power [6][7][8]. Therefore, a ZMZ-409 engine with a capacity of 105 kW was selected, which will be used as a gas generator in testing the turbogenerator.…”

Section: Development Of the Simulation Model Of A Turbogeneratormentioning

confidence: 99%

Turbogenerator: Part 1: Simulation

Lezhnev¹,

Татарников²,

Skvortsov³

et al. 2018

IJET

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The article describes the process of developing a turbogenerator for power plants of small and distributed power generation. The analysis of the component base for the turbogenerator was carried out, and thereof a comparative analysis of possible technical solutions was conducted. The work considered the installation variants of a turbogenerator in the exhaust system, an electric machine of a turbogenerator, types of turbines of a generator. A mathematical model for computation of the output effective and geometric parameters of a turbogenerator was described. The results of computational analysis were presented, and the parameters of the turbogenerator being developed were selected. Based on the results of the work done the conclusions were made

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“…This clarifies that the turbogenerator here considered, and the whole hybrid propulsion system shown in Figure 1, are not commercially available at the moment. The only commercially available products are composed of a radial turbine for turbocharging application connected to an electric generator [15][16][17] and are designed exclusively to supply the electric accessories of traditional vehicles, thus producing maximum output power within 6 kW. Given the lack of adequate references on the market, as indicated in the scientific literature, and in their preliminary studies, the authors considered a constant turbine thermomechanical efficiency η T,tm (i.e., the product of the total to static isentropic efficiency η t,s and the mechanical efficiency η m ), i.e., independent of the turbine speed and pressure ratio; more in detail, in their preliminary analysis, the authors considered two different levels of thermomechanical efficiency, namely 0.70 and 0.75.…”

Section: Introductionmentioning

confidence: 99%

Hybrid Propulsion Efficiency Increment through Exhaust Energy Recovery—Part 1: Radial Turbine Modelling and Design

et al. 2023

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The efficiency of Hybrid Electric Vehicles (HEVs) may be substantially increased if the energy of the exhaust gases, which do not complete the expansion inside the cylinder of the internal combustion engine, is efficiently recovered by means of a properly designed turbogenerator and employed for vehicle propulsion; previous studies, carried out by the same authors of this work, showed a potential hybrid vehicle fuel efficiency increment up to 15% by employing a 20 kW turbine on a 100 HP rated power thermal unit. The innovative thermal unit here proposed is composed of a supercharged engine endowed with a properly designed turbogenerator, which comprises two fundamental elements: an exhaust gas turbine expressly designed and optimized for the application, and a suitable electric generator necessary to convert the recovered energy into electric energy, which can be stored in the on-board energy storage system of the vehicle. In these two parts, the realistic efficiency of the innovative thermal unit for hybrid vehicle is evaluated and compared to a traditional turbocharged engine. In Part 1, the authors present a model for the prediction of the efficiency of a dedicated radial turbine, based on a simple but effective mean-line approach; the same paper also reports a design algorithm, which, owing to some assumptions and approximations, allows a fast determination of the proper turbine geometry for a given design operating condition. It is worth pointing out that, being optimized for quasi-steady power production, the exhaust gas turbine considered is quite different from the ones commonly employed for turbocharging application; for this reason, and in consideration of the required power size, such a turbine is not available on the market, nor has its development been previously carried out in the scientific literature. In the Part 2 paper, a radial turbine geometry is defined for the thermal unit previously calculated, employing the design algorithm described in Part 1; the realistic energetic advantage that could be achieved by the implementation of the turbogenerator on a hybrid propulsion system is evaluated through the performance prediction model under the different operating conditions of the thermal unit. As an overall result, it was estimated that, compared to a reference traditional turbocharged engine, the turbocompound system could gain vehicle efficiency improvement between 3.1% and 17.9%, depending on the output power level, while an average efficiency increment of 10.9% was determined for the whole operating range.

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Modelling and Testing of a Turbo-generator System for Exhaust Gas Energy Recovery

Cited by 19 publications

References 2 publications

Efficiency Advantages of the Separated Electric Compound Propulsion System for CNG Hybrid Vehicles

Efficiency Advantages of the Separated Electric Compound Propulsion System for CNG Hybrid Vehicles

Turbogenerator: Part 1: Simulation

Hybrid Propulsion Efficiency Increment through Exhaust Energy Recovery—Part 1: Radial Turbine Modelling and Design

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