Potential for energy and emissions of asymmetric twin-scroll turbocharged diesel engines combining inverse Brayton cycle system

Zhu, Dengting; Zheng, Xinqian

doi:10.1016/j.energy.2019.05.028

Cited by 17 publications

(5 citation statements)

References 36 publications

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“…The TPLC of the diffuser system with induced gas into the diffuser which includes the total pressure loss of the induced structure is defined as equation (12). Where j 1 is the TPLC of the diffuser system with induced gas into the diffuser; P 2i is the static pressure of the induced structure inlet.…”

Section: Definition Of Adiabatic Efficiency Of the Compressor With In...mentioning

confidence: 99%

“…It was demonstrated that the engine of asymmetric twin-scroll turbine EGR has lower fuel consumption than VNT EGR. 12 To improve the fuel economy at the high-speed range, Zhu and Zheng studied the asymmetric twin-scroll turbine EGR with two exhaust gas recirculation circuits 13 and with two wastegates. 14 The results showed such strategies were more effective than the origin asymmetric twin-scroll turbine EGR.…”

Section: Introductionmentioning

confidence: 99%

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Numerical investigation on the compressor for gas-entraining diffuser EGR

Zhu

Wang

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part D:

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Exhaust Gas Recirculation (EGR) is an effective way to reduce nitrogen oxide (NO x) emissions, and the EGR application increases the engine backpressure to some extent. In this paper, a new EGR method named gas-entraining diffuser EGR was proposed to reduce pumping loss. It introduces the exhaust gas into the compressor diffuser inlet where the static pressure is the lowest without blades fouled by exhaust gas. As a result, lower pressure at the turbine upstream can achieve EGR. Then, a newly designed induced structure not only introduces exhaust gas into the compressor diffuser but also reduces the energy loss caused by EGR application. Furthermore, the performance of compressor with different induced angles of the induced structure was investigated using simulation method. Results showed that the compressor’s adiabatic efficiency was the best when the induced angle was 20°. Regarding the induced angle of 20°, the adiabatic efficiency drop of compressor was in the range of 0.8%–12%. Approximately 10% of the adiabatic efficiency drop was caused by the induced structure, the other was mainly from the flow loss and mixing loss in diffuser system. The induced structure mainly affected the static pressure difference between induced structure inlet and impeller outlet ([Formula: see text]). When the impeller mass flow was 0.23 kg/s, [Formula: see text] was 11.21, 13.95, 15.59, 17.18 kPa respectively with corresponding induced angles of 20°, 30°, 40°, 50°. The primary energy loss leading to the adiabatic efficiency drop of compressor with induced structure occurred in diffuser system. It was caused by the mixing process of induced gas and impeller exit gas, and the enhanced effect from the shroud side’s impeller jet-wake and volute tongue.

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Section: Definition Of Adiabatic Efficiency Of the Compressor With In...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Numerical investigation on the compressor for gas-entraining diffuser EGR

Zhu

Wang

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part D:

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“…Over the past few years, an asymmetric twin-scroll turbine (ATST) has become as a novel turbocharging technology with two scrolls in two critical areas. 1 The small scroll linked to the route of exhaust gas recirculation (EGR) aims to generate higher turbine inlet pressure, which achieves a sufficiently high EGR rate. 2 Moreover, the large scroll, termed as lambda scroll, aims at achieving a sufficiently high air fuel ratio and lowering pump loss by high turbine running efficiency and effective breathing matching of the engine and turbine.…”

Section: Introductionmentioning

confidence: 99%

“…Lately, Zhu and Zheng further, achieved significantly enhancement for fuel economy for the ATST on an engine with two EGR routes 16 and an engine with an inverse Brayton cycle. 17 The mentioned above studies primarily complied with the steady-state turbine performance.…”

Section: Introductionmentioning

confidence: 99%

Effect of balance valve on exhaust pulse energy of a heavy-duty diesel engine equipped an asymmetric twin-scroll turbine

Jin

Pan

Cao

2022

Proceedings of the Institution of Mechanical Engineers, Part D:

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The exhaust pulse energy of engine is capable of driving the asymmetric twin-scroll turbine to run complicatedly in a wider flow range, which significantly causes more difficulty of an asymmetric twin-scroll turbine to match a diesel engine. In the present study, It was initially analyzed that an engine exhaust pulse energy of an asymmetric twin-scroll turbine with a balance valve. First, a pulsating flow model of asymmetric twin-scroll turbine was built to decouple the operation states of the small and large scroll turbines. Second, the experiments of asymmetric twin-scroll turbine were performed on a turbine test rig and an engine performance stand to determine the operation rules of turbine flow parameter, turbine efficiency, blade speed ratio, as well as turbine available energy. Asthe balance valve opens, the flow parameter of twin-scroll would perform more broadly around the swallow capacity curves of equal admission. Moreover, the fully-opened balance valve would make the exhaust pulse strength at the small and large scroll inlets sharply degrade by about 25% and 21%, the cycle turbine efficiency enhance by nearly 3%, the turbine available energy and BSFC degrade by about 8.15% and 2.9% at 800 rpm full load engine condition; At 1100 rpm full load engine condition, the exhaust pulse strength at the small and large scroll inlets only degraded by about 7.2% and 5.8%, the cycle turbine efficiency enhanced by about 4%, the turbine available energy and BSFC improved by about 3.7% and 2.1%. Lastly, this study delved into the distributions of the balance valve opening rate and the pulse strength at the small and large scroll inlets at full engine map.

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“…Thus, ATST is admittedly effective in balancing the NO x and fuel consumption of EGR engines. 24 Daimler’s heavy-duty engines of OM470, OM471, OM472 and OM473 were outfitted the ATST turbo. Müller et al 25 from Daimler considered that the turbine driven by small scroll (small scroll turbine) ran at very low efficiency and a low turbine reaction degree, which could achieve sufficiently high EGR drive capability.…”

Section: Introductionmentioning

confidence: 99%

Effect of balance valve on an asymmetric twin-scroll turbine for heavy-duty diesel engine

Jin

Pan

Lü³

et al. 2020

International Journal of Engine Research

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A conventional asymmetric twin-scroll turbine with wastegate is capable of effectively tackling down the contradiction between fuel economy degradation and low nitrogen oxide emissions. However, as the engine speed has been rising at middle- and high-speed ranges, the pressure of small scroll inlet will be increasingly higher as compared with the intake pressure, thereby worsening fuel economy. In this study, a novel turbocharging technology of asymmetric twin-scroll turbine with a balance valve was first analyzed to more effectively balance the engine fuel economy and emission. The experiments on turbine test rig and engine performance were performed to explore the effects of balance valve on turbine performance, asymmetric ratio, exhaust gas recirculation rate, as well as engine performance. As the balance valve open degree was elevated, the turbine flow parameter was being extended, while the turbine efficiency was enhanced. Moreover, a lower asymmetric ratio could lead to a broader flow parameter range between that of partial admission and equal admission, thereby resulting in a broader regulating range of exhaust gas recirculation rate. In contrast with the asymmetric twin-scroll turbine with wastegate, the turbine running efficiency of asymmetric twin-scroll turbine with balance valve was enhanced by nearly 2%–11% at middle and high engine speed ranges, while the fuel economy was improved by nearly 1.5%–8%.

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Potential for energy and emissions of asymmetric twin-scroll turbocharged diesel engines combining inverse Brayton cycle system

Cited by 17 publications

References 36 publications

Numerical investigation on the compressor for gas-entraining diffuser EGR

Numerical investigation on the compressor for gas-entraining diffuser EGR

Effect of balance valve on exhaust pulse energy of a heavy-duty diesel engine equipped an asymmetric twin-scroll turbine

Effect of balance valve on an asymmetric twin-scroll turbine for heavy-duty diesel engine

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