Waste heat recovery using a novel high performance low pressure turbine for electric turbocompounding in downsized gasoline engines: Experimental and computational analysis

Mamat, Azuddin; Martinez-Botas, Ricardo; Rajoo, Srithar; Romagnoli, Alessandro; Petrovic, Simon

doi:10.1016/j.energy.2015.06.010

Cited by 40 publications

(29 citation statements)

References 14 publications

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“…When the exhaust valve opens (point 5 in Figure 1), the maximum available exhaust energy can be represented by two areas: the exhaust gas energy (area 6-7-8-9) and the blow-down energy (area 5-10-9-5). The high exhaust pressure expands in the main turbine (5)(6)(7)(8)(9)(10)(11). Therefore, the remaining exhaust gas pressure which could be expanded in the second turbine goes from point 11 to 10, and the available energy for the secondary turbine can be represented by area (11-10-8-14-11).…”

Section: Turbocompounding For Energy Recoverymentioning

confidence: 99%

“…In a small car segment the mass flow rate of the exhaust gases is in the range of 0.02 kg/s to 0.1 kg/s and the available pressure at the main turbine exit is approximately 1.05 bar to 1.3 bar. At such low pressures and mass flow rates, commercially available turbines fail to provide an adequate response thus justifying the need for a high performance LPT design to fill the existing technology gap [9][10][11][12]. Zhao et al attributed the poor performance of LPTs at low pressure ratios to high entropy generation rates on the pressure surface due to flow separation at such low load conditions [13].…”

Section: Low Pressure Turbinementioning

confidence: 99%

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Design methodology of a low pressure turbine for waste heat recovery via electric turbocompounding

Mamat

Martinez-Botas

Rajoo

et al. 2016

Applied Thermal Engineering

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This paper presents a design methodology of a high performance Low Pressure Turbine (LPT) for turbocompounding applications to be used in a 1.0 L “cost-effective, ultra-efficient heavily downsized gasoline engine for a small and large segment passenger car”. Under this assumption, the LPT was designed to recover the latent energy of discharged exhaust gases at low pressure ratios (1.05–1.3) and to drive a small electric generator with a maximum power output of 1.0 kW. The design speed was fixed at 50,000 rpm with a pressure ratio, PR of 1.08. Commercially available turbines are not suitable for this purpose due to the very low efficiencies experienced when operating in these pressure ratio ranges. By fixing all the LPT requirements, the turbine loss model was combined with the geometrical model to calculate preliminary LPT geometry. The LPT features a mixed-flow turbine with a cone angle of 40° and 9 blades, with an inlet blade angle at radius mean square of +20°. The exit-to-inlet area ratio value is approximately 0.372 which is outside of the conventional range indicating the novelty of the approach. A single passage Computational Fluid Dynamics (CFD) model was applied to optimize the preliminary LPT design by changing the inlet absolute angle. The investigation found the optimal inlet absolute angle was 77°. Turbine off-design performance was then predicted from single passage CFD model. A rapid prototype of the LPT was manufactured and tested in Imperial College turbocharger testing facility under steady-state and pulsating flow. The steady-state testing was conducted over speed parameter ranges from 1206 rpm/K0.5 to 1809 rpm/K0.5. The test results showed a typical flow capacity trend as a conventional radial turbine but the LPT had higher total-to-static efficiency, ηt-s in the lower pressure ratio regions. A maximum total-to-static efficiency, ηt-s of 0.758 at pressure ratio, PR ≈ 1.1 was found, no available turbines exist in this range as parameters. A validation of the predicted single passage CFD analysis for the off-design performance against the LPT test result found a minimum total-to-static efficiency Standard Deviation of ±0.026 points for the speed parameter of 1507 rpm/K0.5. A minimum Mass Flow Parameter Standard Deviation of ±0.091 kg/s K0.5 bar is found at 1206 rpm/K0.5

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Section: Turbocompounding For Energy Recoverymentioning

confidence: 99%

Section: Low Pressure Turbinementioning

confidence: 99%

Design methodology of a low pressure turbine for waste heat recovery via electric turbocompounding

Mamat

Martinez-Botas

Rajoo

et al. 2016

Applied Thermal Engineering

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“…Various studies also concern turbocompounds on spark-ignition engines. In [25] a theoretical analysis of turbocharging benefits on a 2000 cm 3 spark-ignition engine is shown whereas in [24] turbocharging benefits on a 1000 cm 3 spark-ignition engine are supported by experimental results.…”

Section: Introductionmentioning

confidence: 96%

“…This topology may further benefits from innovation in engine design, such as the introduction of turbocompound (TC) systems. As observed by Jain et al [23], turbocompound conditions are quite occasional in real road missions, thus, they do not render beneficial the introduction of the TC system; as a matter of fact, turbocompounding benefits are substantial at high load [23][24][25][26][27][28]. This aspect explains why today this technology is not used on medium size cars and is developed only for sportive cars or trucks and buses, characterized by frequent high load demand.…”

Section: Introductionmentioning

confidence: 99%

Turbocompound Power Unit Modelling for a Supercapacitor-Based Series Hybrid Vehicle Application

et al. 2020

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In this paper, starting from the measurements available for a 2000 cm3 turbocharged diesel engine, an analytical model of the turbocharger is proposed and validated. The model is then used to extrapolate the efficiency of a power unit with a diesel engine combined with a turbocompound system. The obtained efficiency map is used to evaluate the fuel economy of a supercapacitor-based series hybrid vehicle equipped with the turbocompound power unit. The turbocompound model, in accordance with the studies available in the technical literature, shows that the advantages (in terms of efficiency increase) are significant at high loads. For this reason, turbocompound introduction allows a significant efficiency improvement in a series hybrid vehicle, where the engine always works at high-load. The fuel economy of the proposed vehicle is compared with other hybrid and conventional vehicle configurations.

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“…Engine downsizing is proven as the most promising approach in fuel consumption reduction [3]- [5], which uses a smaller capacity engine to provide the power of a larger engine. The downsized engine allows a larger area of its operating range to be more efficiently used for most of the time, since the average engine operating points become closer to its high fuel efficiency zone.…”

Section: Introductionmentioning

confidence: 99%

Robust control of electrified turbocharged diesel engines

Zhao

Winward

Yang

et al. 2016

2016 IEEE 55th Conference on Decision and Control (CDC)

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Waste heat recovery using a novel high performance low pressure turbine for electric turbocompounding in downsized gasoline engines: Experimental and computational analysis

Cited by 40 publications

References 14 publications

Design methodology of a low pressure turbine for waste heat recovery via electric turbocompounding

Design methodology of a low pressure turbine for waste heat recovery via electric turbocompounding

Turbocompound Power Unit Modelling for a Supercapacitor-Based Series Hybrid Vehicle Application

Robust control of electrified turbocharged diesel engines

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