Numerical Evaluation of Spray-Guided Glow Plug Assistance on Gasoline Compression Ignition During Cold Idle Operation in a Heavy-Duty Diesel Engine

2020 ◽  
Author(s):  
Le Zhao ◽  
Yuanjiang Pei ◽  
Yu Zhang ◽  
Praveen Kumar ◽  
Tom Tzanetakis ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Combustion Process ◽  
Cold Start ◽  
Compression Ignition ◽  
Heavy Duty ◽  
Glow Plug ◽  
Fuel Vaporization ◽  
Heavy Duty Diesel Engine ◽  
Heavy Duty Diesel ◽  
Ignition And Combustion

Abstract Starting compression ignition engines under cold conditions is extremely challenging, due to insufficient fuel vaporization, heavy wall impingement, and low ignitability of the fuel. For gasoline compression ignition (GCI) combustion strategies, which offer the potential for an enhanced NOx-PM tradeoff with diesel-like fuel efficiency, robust ignition and combustion in very cold conditions pose a significant challenge due to the low reactivity of gasoline fuels. Based on the previous understanding of the spray, ignition and combustion processes for a GCI engine under cold conditions, this study focuses on investigating the cold combustion performance of a heavy-duty GCI engine with glow plug ignition assist. Glow plugs, commonly used for low temperature cold starts in diesel engines, are used to pre-heat a segment of the mixture to improve its ignitability. Here, CFD studies are carried out to explore the influence of a spray-guided glow plug on the spray and combustion behavior of a GCI engine under cold operating conditions. In a prior study, the underlying CFD model has been validated using experimental data from a six-cylinder, 15 L heavy-duty diesel engine operating with a compression ratio (CR) of 17.3 at a 600 rpm cold idle condition with RON92 E0 gasoline. The energy intensity required by the glow plug to deliver stable combustion isparametrically studied. The size and location of the glow plug are also parametrically varied to evaluate their effects on the combustion process. The influence of the glow plug on the in-cylinder mixture distribution and the ensuing combustion process is also investigated. In particular, the localized fuel spray distribution and mixture formation near the glow plug are examined. The results reveal that the glow plug enhances GCI combustion under cold idle conditions and that the spray-guided glow plug improves fuel vaporization, leading to a rich mixture near the glow plug and an enhancement of the combustion efficiency. In addition, the effectiveness of the glow plug at a low ambient temperature of 0°C and a 200 rpm cold start condition is evaluated. These simulations suggest that the glow plug can improve the cold start performance of a GCI engine.

A Computational Investigation of Piston Bowl Geometry and Injector Spray Pattern Effects on Gasoline Compression Ignition in a Heavy-Duty Diesel Engine

2019 ◽  
Author(s):  
Yu Zhang ◽  
Yuanjiang Pei ◽  
Meng Tang ◽  
Michael Traver
Keyword(s):  
Diesel Engine ◽  
Fuel Efficiency ◽  
Compression Ignition ◽  
Swirl Ratio ◽  
Heavy Duty ◽  
Load Range ◽  
Spray Pattern ◽  
Piston Bowl ◽  
Heavy Duty Diesel Engine ◽  
Heavy Duty Diesel

Abstract This study computationally investigates the potential of utilizing gasoline compression ignition (GCI) in a heavy-duty diesel engine to address a future ultra-low tailpipe NOx standard of 0.027 g/kWh while achieving high fuel efficiency. By conducting closed-cycle, full-geometry, 3-D computational fluid dynamics (CFD) combustion simulations, the effects of piston bowl geometry, injector spray pattern, and swirl ratio (SR) were investigated for a market gasoline. The simulations were performed at 1375 rpm over a load range from 5 to 15 bar BMEP. The engine compression ratio (CR) was increased from 15.7 used in previous work to 16.5 for this study. Two piston bowl concepts were studied with Design 1 attained by simply scaling from the baseline 15.7 CR piston bowl, and Design 2 exploring a wider and shallower combustion chamber design. The simulation results predicted that through a combination of the wider and shallower piston bowl design, a 14-hole injector spray pattern, and a swirl ratio of 1, Design 2 would lead to a 2–7% indicated specific fuel consumption (ISFC) improvement over the baseline by reducing the spray-wall interactions and lowering the in-cylinder heat transfer loss. Design 1 (10-hole and SR2) showed a more moderate ISFC reduction of 1–4% by increasing CR and the number of nozzle holes. The predicted fuel efficiency benefit of Design 2 was found to be more pronounced at low to medium loads.

Piston Bowl Geometry Effects on Gasoline Compression Ignition in a Heavy-Duty Diesel Engine

2020 ◽  
Author(s):  
Meng Tang ◽  
Yuanjiang Pei ◽  
Hengjie Guo ◽  
Yu Zhang ◽  
Roberto Torelli ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Design Optimization ◽  
Software Package ◽  
Compression Ignition ◽  
Heavy Duty ◽  
Light Load ◽  
Heavy Duty Diesel Engine ◽  
Air Mixing ◽  
Heavy Duty Diesel ◽  
Load Conditions

Abstract A design optimization campaign was conducted to search for improved combustion profiles that enhance gasoline compression ignition in a heavy-duty diesel engine with a geometric compression ratio of 17.3. Three-dimensional computational fluid dynamics simulations were employed using the software package CONVERGE. A large-scale design of experiments (DoE) approach was used for the optimization. The main parameters explored include geometric features, injector specifications, and swirl motion. Both stepped-lip bowls and re-entrant bowls were included in the optimization effort in order to assess their respective performance implications. A total of 256 design candidates were prepared using the software package CAESES for automated and simultaneous geometry generation and combustion recipe perturbation. The design optimization was conducted for three engine load points representing light to medium load conditions. The design candidates were evaluated for fuel efficiency, emissions, fuel-air mixing characteristics, and global combustion behavior. Simulation results show that the optimum designs were all stepped-lip bowls, which exhibited better overall performance than re-entrant bowls due to improvements in fuel-air mixing, as well as reduced heat loss and emissions formation. Improvements in indicated specific fuel consumption of up to 3.2% were achieved while meeting engine-out NOx emission targets of 1–1.5 g/kW·hr. Re-entrant bowls performed worse compared to the baseline design, and significant performance variations occurred across the load points. Specifically, the re-entrant bowls were on par with the stepped-lip bowls under light load conditions, but significant deteriorations occurred under higher load conditions. As a final task, selected optimized designs were then evaluated under simulated full-load conditions.

Piston Bowl Geometry Effects on Gasoline Compression Ignition in a Heavy-Duty Diesel Engine

2021 ◽  
Author(s):  
Meng Tang ◽  
Yuanjiang Pei ◽  
Hengjie Guo ◽  
Yu Zhang ◽  
Roberto Torelli ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Compression Ignition ◽  
Heavy Duty ◽  
Piston Bowl ◽  
Heavy Duty Diesel Engine ◽  
Geometry Effects ◽  
Heavy Duty Diesel
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