Bir Metan Yakıtlı CAI Motor üzerinde EGR ve Aşırı Hava Oranı Etkilerinin Hesaplamalı Çalışması

Abstract

Bu kağıt metan yakıt kullanarak kontrollü otomatik ateşleme (CAI), dört zamanlı, tek silindirli motor, sayısal analizini sunmaktadır. Bu çalışmanın amacı gazı devridaim (EGR) oranı yanma, emisyon ve motor performansı nasıl etkilediğini egzoz belirlemektir. EGR oranları% 27,% 32,% 37 ve 1,0, 1,5, 2,0 ve 2,5 fazla hava oranlı kütleye göre% 42 olarak seçilmiştir. 570 K bir de silindir sıcaklığı emme valfi kapanış saati (IVC) kabul edildi ve 1500 rpm motor devir Tüm olgularda kullanıldı. Hesaplamalı Akışkanlar Dinamiği (CFD) kodu Fluent sayısal analiz için kullanılmıştır. Sayısal modelleme Renormalizasyon Grubu Teorisi (RNG) k- modeli kullanılarak, dikkate türbülans etkisi alarak çözüldü.

Sonuçları-silindir basınç, sıcaklık, ısı salınım oranı, basınç yükselme hızı, yanma süresi, fren çalışmaları, belirli NOx ve CO emisyonları, ısıl verim ve özgül yakıt tüketimi üzerinde önemli etkilere sahip EGR oranı ve aşırı hava oranının bu artışa işaret etmektedir. Ayrıca, CAI yanma  EGR oranı fazla hava oranının düşük seviye (% 32 kadar) oldu (basınç yükselme hızı, yüksek sıcaklık değeri ve yüksek düzeyde snox emisyon artışa yol açmaktadır hızlı ısı salım oranı sonuçlandı 1 ve 1,5) değer. Düşük düzeyde snox emisyonu ile sonuçlanan CAI yanma elde etmek için, karışım fazla% 32 EGR oranını içeren veya yalın haline gelmelidir.

Keywords

• CAI,CFD,EGR,metan,ısı salınım oranı

Computational Study of EGR and Excess Air Ratio Effects on a Methane Fueled CAI Engine

Abstract

This paper presents the numerical analysis of a controlled auto ignition (CAI), four stroke, single cylinder engine, by using methane fuel. The goal of this study was to determine how exhaust gas recirculation (EGR) rate affects combustion, emission and engine performance. The EGR rates were selected as 27 %, 32 %, 37 %, and 42 % by mass with excess air ratios of 1.0, 1.5, 2.0, and 2.5. An in-cylinder temperature of 570 K was considered at intake valve closing time (IVC) and an engine speed of 1500 rpm was used for all cases. The Computational Fluid Dynamics (CFD) code FLUENT was used for numerical analysis. The numerical modeling was solved by taking into consideration the effect of turbulence, by using the Renormalization Group Theory (RNG) k- model. The results indicate that increase in EGR rate and excess air ratio have significant effects on in-cylinder pressure, temperature, heat release rate, pressure rise rate, combustion duration, brake work, specific NOx and CO emissions, thermal efficiency and specific fuel consumption. Moreover, CAI combustion resulted in a rapid heat release rate which gives rise to an increase in the pressure rise rate, high temperature value and high level SNOx emission, when EGR rate was low level (up to 32 %) for excess air ratio() value of 1 and 1.5. To achieve CAI combustion resulting in low level SNOx emission, the mixture must include an EGR rate of more than 32 % or become leaner.

Keywords

• CAI, CFD, EGR, methane, heat release rate

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