Influence of Air/Fuel Ratio on Cyclic Variation and Exhaust Emission in Natural Gas SI Engine

Author(s):  
Livier Ben ◽  
Nathalie Raud-Ducros ◽  
Remy Truquet ◽  
Georges Charnay
Energies ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 173 ◽  
Author(s):  
Lei Meng ◽  
Xiaofeng Wang ◽  
Chunnian Zeng ◽  
Jie Luo

The accurate air-fuel ratio (AFR) control is crucial for the exhaust emission reduction based on the three-way catalytic converter in the spark ignition (SI) engine. The difficulties in transient cylinder air mass flow measurement, the existing fuel mass wall-wetting phenomenon, and the unfixed AFR path dynamic variations make the design of the AFR controller a challenging task. In this paper, an adaptive AFR regulation controller is designed using the feedforward and feedback control scheme based on the dynamical modelling of the AFR path. The generalized predictive control method is proposed to solve the problems of inherent nonlinearities, time delays, parameter variations, and uncertainties in the AFR closed loop. The simulation analysis is investigated for the effectiveness of noise suppression, online prediction, and self-correction on the SI engine system. Moreover, the experimental verification shows an acceptable performance of the designed controller and the potential usage of the generalized predictive control in AFR regulation application.


Author(s):  
Rahmat Mohsin ◽  
Zulkefli Yaacob ◽  
Zulkifli Abdul Majid ◽  
Shameed Ashraf

Gas asli termampat (CNG) merupakan bahan api alternatif yang paling berjaya dan digunakan dengan meluas bagi kenderaan terkini yang berada di pasaran. Kenderaan pacuan petrol bagi tujuan ini biasanya dilengkapkan dengan kit penukar gas asli bagi membolehkan operasian dwi-bahan api di antara CNG dan petrol. Pendekatan secara uji kaji ini difokuskan ke atas penggunaan bahan api, emisi ekzos dan kos bahan api di antara operasian gas asli dan petrol. Rig ujian terdiri dari sebuah sistem enjin teksi dwi-bahan api menggunakan 1500 cc dengan 12 injap sistem karburetor adalah dibina khusus. Penggunaan bahan api dan emisi ekzos yang setara diperolehi pada kelajuan putaran seminit (rpm) enjin yang berbeza ketika operasian menggunakan bahan api CNG dan petrol secara berasingan. Pengoperasian rpm enjin tanpa bebanan diubahsuai dari kedudukan pegun kepada kedudukan melebihi 5000 rpm untuk memperolehi profil penggunaan bahan api dan emisi ekzos. Kedua-dua data yang diperolehi ini kemudiannya digunakan bagi mengira kadar udara bahan api enjin. Kesemua ketiga-tiga parameter yang diperolehi digunakan untuk membuat perbandingan terhadap operasian gas asli dan petrol. Pemerhatian yang dibuat menunjukkan kadar udara bahan api bermula dari 19 ke 16.3 bagi operasian petrol dan dari 40 ke 18.7 untuk operasian menggunakan gas asli. Emisi ketika operasian menggunakan CNG jelas menunjukkan penurunan ketara ke atas keluaran hidrokarbon (HC), karbon monoksida (CO), karbon dioksida (CO2) dan nitrogen oksida (NOx) dibandingkan dengan operasian menggunakan petrol. Dari segi kos, penggunaan CNG memberikan keuntungan melebihi 50% terhadap kesemua kelajuan rpm enjin jika dibandingkan dengan operasian menggunakan petrol. Kata kunci: NGV, enjin dwi–bahan api, pengunaan bahan api, emisi ekzos, CNG, gas asli Compressed natural gas (CNG) is the most successful and widely used alternative fuel for vehicles in the market today. Petrol fuelled vehicles are fitted with natural gas vehicle (NGV) conversion kit to enable bi-fuel operation between CNG and petrol. This experimental approach is focused on the fuel consumption, exhaust emission and fuel cost between natural gas and petrol operations. The specially constructed test rig comprises of the bi-fuel fuel system employed in the 1500 cc 12 valves carburettor engine NGV taxis. The inherent fuel consumption and corresponding exhaust emission are acquired at different engine revolution per minute (rpm) during petrol and CNG operation separately. The engine rpm operating without load is varied from idle to more than 5000 rpm to acquire the fuel consumption and exhaust emission profile. These two acquired data are then used to calculate the engine’s air fuel ratio. All three parameters acquired are used to conduct comparisons between petrol and natural gas operation. It is seen that the bi-fuel system operates with air fuel ratio ranging from 19 to 16.3 for petrol operation and ranges from 40 to 18.7 for natural gas operations. The emission during CNG operation clearly shows significant decrease in hydrocarbon (HC), carbon monoxide (CO), carbon dioxide (CO2) and nitrogen oxide (NOx) over the use of petrol. In terms of cost, the use of CNG provides savings exceeding 50% through all engine rpm compared to petrol non-loaded operations. Key words: NGV, bi–fuel engine, fuel consumption, exhaust emission, CNG, natural gas


Energies ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3444
Author(s):  
Lei Meng ◽  
Jie Luo ◽  
Xu Yang ◽  
Chunnian Zeng

Air-fuel ratio (AFR) control is important for the exhaust emission reduction while using the three-way catalytic converter in the spark ignition (SI) engine. However, the transient cylinder air mass is unable to acquire by sensors directly and it may limit the accuracy of AFR control. The complex engine dynamics and working conditions make the intake air estimation a challenge work. In this paper, a novelty design of intake air observer is investigated for the port-injected SI engine. The intake air dynamical modeling and the parameter fitting have been carried out in detail. Extended Kalman Filter (EKF) has been used to optimize the instantaneous cylinder charge estimation and minimize the effort of pump gas fluctuation, random noise, and measurement noise. The experiment validation has been conducted to verify the effectiveness of the proposed method.


1992 ◽  
Author(s):  
William A. Rimkus ◽  
Robert P. Larsen ◽  
Michael G. Zammit ◽  
James G. Davies ◽  
Gregory S. Salmon ◽  
...  

2008 ◽  
Author(s):  
A. Gimelli ◽  
C. Cascone ◽  
O. Pennacchia ◽  
A. Unich ◽  
P. Capaldi

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