CFD analysis of exhaust pipe of a diesel engine

In order to design a diesel engine system and to predict its performance, it is necessary to analyze the gas flow of the intake and exhaust system. Gas flow analysis in a three-dimensional (3D) format needs a high-resolution workstation and an enormous amount of time for analysis. Calculation using the method of characteristics (MOC), which is a gas flow analysis in a one-dimensional (1D) format, has a fast calculation time and can be analyzed with a low-resolution workstation. However, there is a problem with poor accuracy in certain areas. It was assumed that the reason was that 1D could not implement the shape. The error that occurs in the shape of the bent pipe used in the intake and exhaust ports of the diesel engine was analyzed and to find a solution to the low accuracy, the results of the experiment and 1D analysis were compared. The discharge coefficient was calculated using the average mass flow rate, and as a result of applying it, the accuracy was improved for the maximum negative pressure by 0.56–1.93% and the maximum pressure by 3.11–7.86% among the intake pipe pressure results. The difference in phase of the exhaust pipe pressure did not improve. It is considered as a limitation of 1D analysis that does not improve even by applying the discharge coefficient. In the future, we intend to implement a bent pipe that cannot be realized in 1D using a 3D format and to prepare a method to supplement the reliability by using 1D–3D coupling.

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Research on Optimization Design of SCR Nozzle for National VI Heavy Duty Diesel Engine

Catalysts ◽

10.3390/catal9050452 ◽

2019 ◽

Vol 9 (5) ◽

pp. 452 ◽

Cited By ~ 1

Author(s):

Feng Qian ◽

Dong Ma ◽

Neng Zhu ◽

Peng Li ◽

Xiaowei Xu

Keyword(s):

Diesel Engine ◽

Conversion Efficiency ◽

Optimization Design ◽

Exhaust Pipe ◽

Heavy Duty ◽

Deposit Formation ◽

Nox Conversion ◽

Heavy Duty Diesel ◽

Scr System ◽

Nox Conversion Efficiency

For the National VI heavy-duty diesel vehicles, NOx emission regulations are becoming more and more stringent, and the selective catalytic reduction (SCR) system has become a necessary device. The design of the adblue nozzle in the SCR system is especially critical, directly affecting the NOx conversion efficiency and deposit formation. According to the structure of a National VI diesel engine exhaust pipe and SCR system, the nozzle is optimized by computational fluid dynamics (CFD) method to avoid the collision between the urea droplets and the exhaust pipe wall, to ensure that the exhaust gas and the urea droplets are as much as possible in full contact to ensure a sufficient urea pyrolysis. With the optimized nozzle, the NH3 distribution uniformity of the inlet face of the SCR catalyst can increase from 0.58 to 0.92. Additionally, test verifications are implemented based on the spray particle size test and the engine bench tests; the results show that the Sauter mean diameter of the optimized nozzle is more decreased than the initial nozzle and that the NOx conversion efficiency of the World Harmonized Transient Cycle (WHTC) and World Harmonized Stationary Cycle (WHSC) cycle improves by nearly 3%; additionally, it can also avoid deposit formation.

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Mathematical Validation of Optimized Design of EGR Cooler of CRDI Diesel Engine for NOx Emission Control using CFD Analysis

International Journal of Engineering Trends and Technology ◽

10.14445/22315381/ijett-v63p203 ◽

2018 ◽

Vol 63 (1) ◽

pp. 10-16

Author(s):

Rambhajan Prajapati ◽

◽

Vishal Achwal ◽

Suman Sharma

Keyword(s):

Diesel Engine ◽

Emission Control ◽

Nox Emission ◽

Optimized Design ◽

Cfd Analysis ◽

Egr Cooler

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Low-sooting combustion in a small-bore high-speed direct-injection diesel engine using narrow-angle injectors

Proceedings of the Institution of Mechanical Engineers Part D Journal of Automobile Engineering ◽

10.1243/09544070jauto751 ◽

2008 ◽

Vol 222 (10) ◽

pp. 1927-1937 ◽

Cited By ~ 9

Author(s):

T-G Fang ◽

R E Coverdill ◽

C-F F Lee ◽

R A White

Keyword(s):

Diesel Engine ◽

High Speed ◽

Direct Injection ◽

Fuel Efficiency ◽

Operating Conditions ◽

Injection Timing ◽

Exhaust Pipe ◽

Injection Angle ◽

Direct Injection Diesel Engine ◽

Combustion Flame

An optically accessible high-speed direct-injection diesel engine was used to study the effects of injection angles on low-sooting combustion. A digital high-speed camera was employed to capture the entire cycle combustion and spray evolution processes under seven operating conditions including post-top-dead centre (TDC) injection and pre-TDC injection strategies. The nitrogen oxide (NO x) emissions were also measured in the exhaust pipe. In-cylinder pressure data and heat release rate calculations were conducted. All the cases show premixed combustion features. For post-TDC injection cases, a large amount of fuel deposition is seen for a narrower-injection-angle tip, i.e. the 70° tip, and ignition is observed near the injector tip in the centre of the bowl, while for a wider-injection-angle tip, namely a 110° tip, ignition occurs near the spray tip in the vicinity of the bowl wall. The combustion flame is near the bowl wall and at the central region of the bowl for the 70° tip. However, the flame is more distributed and centralized for the 110° tip. Longer spray penetration is found for the pre-TDC injection timing cases. Liquid fuel impinges on the bowl wall or on the piston top and a fuel film is formed. Ignition for all the pre-TDC injection cases occur in a distributed way in the piston bowl. Two different combustion modes are observed for the pre-TDC injection cases including a homogeneous bulky combustion flame at earlier crank angles and a heterogeneous film combustion mode with luminous sooting flame at later crank angles. In terms of soot emissions, NO x emissions, and fuel efficiency, results show that the late post-TDC injection strategy gives the best performance.

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