Experimental Analysis of Combustion and Cycle-to-Cycle Variations in a Methanol-Diesel Dual-Fuel RCCI Engine

Year 2025, Volume: 1 Issue: 2, 74 - 85, 30.12.2025

Mustafa Temür

Abstract

This study experimentally investigates the combustion characteristics and cyclic variations of a methanol–diesel dual-fuel RCCI application in a four-cylinder, turbocharged diesel engine. The experiments were carried out at a constant engine speed of 1750 rpm, corresponding to the maximum torque condition, and at four different load levels (40, 60, 80, and 100 Nm). The findings indicate that the coefficients of variation increase with increasing engine load and methanol flow rate. In particular, values exceeding 10% for the coefficients of variation of the indicated mean effective pressure and maximum pressure suggest reduced combustion stability and a higher tendency for knocking. Therefore, optimization of the methanol ratio and operating conditions is necessary to ensure safe and stable engine operation. One of the key findings of the study is that the pressure rise rate increases with increasing engine load and methanol flow rate. Specifically, the value of 4.59 bar/°CA obtained with the highest methanol ratio (M21) at 100 Nm load approached the knock limit of 5 bar/°CA, which constrains the stable operating range of the engine.

Keywords

RCCI , Methanol , Combustion

Metanol-Dizel Çift Yakıtlı Bir RCCI Motorunda Yanma ve Çevrimsel Değişimlerin Deneysel Analizi

Abstract

Bu çalışmada, dört silindirli, turboşarjlı bir dizel motorda metanol-dizel çift yakıtlı RCCI uygulamasının yanma ve çevrimsel değişimlerini deneysel olarak incelemektedir. Deneyler, motorun maksimum tork ürettiği 1750 d/d sabit devirde ve dört farklı yük seviyesinde (40, 60, 80 ve 100 Nm) gerçekleştirilmiştir. Elde edilen bulgular, motor yükü ve metanol debisi arttıkça çevrimsel değişim katsayıları yükselmektedir. Özellikle, ortalama indike basınç ve maksimum basınç çevrimsel değişim katsayılarının değerlerinin %10'un üzerine çıkması, yanma kararlılığının azaldığını ve vuruntu eğiliminin arttığını göstermektedir. Bu durum, motorun güvenli ve kararlı çalışması için metanol oranının ve işletme koşullarının optimize edilmesini zorunlu kılmaktadır. Çalışmanın önemli bulgularından biri de, motor yükü ve metanol debisindeki artışla basınç artış oranlarının yükselmesidir. Özellikle 100 Nm yükte en yüksek metanol oranı (M21) ile elde edilen 4,59 bar/° değeri, motorun kararlı çalışma bölgesini sınırlayan 5 bar/°KMA olan vuruntu sınırına yaklaşmıştır.

Keywords

RCCI , Metanol , Yanma

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