Effects of Injector Clogging and Hydrogen Energy Fraction on the Combustion and Emission Characteristics of a Four-Stroke Hydrogen/Diesel Dual Fuel Marine Engine at Different Intake Air Temperatures: A Numerical Study

Abstract

This study numerically investigates the combined effects of injector clogging ratios (10%, 20%, 30%, 40%, 50%), hydrogen energy fractions (HEF20, HEF40, HEF60), and intake air temperatures (340 K, 351 K, 360 K) on the in-cylinder combustion and emission characteristics of a four-stroke hydrogen/diesel dual fuel marine engine. Based on an analysis of 45 different simulation scenarios, the study details in-cylinder pressure, heat release rate, mean temperature, and the mole fractions of NOX, HC, CO2, CO, CH2O, and OH. The research findings reveal that injector clogging is the most dominant parameter affecting engine performance changes; specifically, increasing the clogging ratio from 10% to 50% caused radical decreases of up to 17.3% in peak cylinder pressure and 42.4% in the maximum heat release rate. It was observed that the hydrogen enrichment strategy significantly compensated for this performance loss, as the HEF60/360 K configuration under 50% clogging outperformed the HEF20/340 K baseline at 10% clogging in terms of heat release performance. However, this improvement led to a 35% increase in NOX emissions compared to low HEF conditions. The clogging range between 30% and 40%, where heat release and OH radical concentrations exhibit non-linear degradation, is identified as a critical "fouling threshold." From a diagnostic perspective, the shifting of the peak CH2O value from near Top Dead Center (TDC) to approximately 20° Crank Angle after TDC with increasing clogging is presented to the literature as a characteristic "cool flame timing indicator." The suppression of the OH radical by up to 70% under severe clogging conditions makes this species the most sensitive indicator of combustion quality. The data obtained serve as a technical guide for condition-based maintenance planning and optimized hydrogen blending strategies in marine propulsion systems subject to IMO Tier III emission standards.

Keywords

• Hydrogen/Diesel Dual Fuel Marine Engine
• Injector clogging
• Hydrogen energy fraction
• Intake air temperature
• Combustion and emission characteristics

Farklı Emme Havası Sıcaklıklarında Dört Zamanlı Bir Hidrojen/Dizel Çift Yakıtlı Gemi Motorunun Yanma ve Emisyon Karakteristikleri Üzerinde Enjektör Tıkanıklığı ve Hidrojen Enerji Fraksiyonunun Etkileri: Sayısal Bir Çalışma

Abstract

Bu çalışma, dört zamanlı hidrojen/dizel çift yakıtlı gemi makinesinde; enjektör tıkanıklık oranı (%10, %20, %30, %40, %50), hidrojen enerji fraksiyonu (HEF20, HEF40, HEF60) ve emme havası sıcaklığının (340 K, 351 K, 360 K) silindir içi yanma ve emisyon karakteristikleri üzerindeki kombine etkilerini sayısal olarak incelemektedir. Toplam 45 farklı simülasyon senaryosu üzerinden gerçekleştirilen analizlerde; silindir içi basınç, ısı salınım oranı, ortalama sıcaklık ve NOX, HC, CO2, CO, CH2O ile OH mol fraksiyonları detaylandırılmıştır. Araştırma bulguları, motor performansındaki değişimde en baskın parametrenin enjektör tıkanıklığı olduğunu ortaya koymaktadır. Tıkanıklık oranının %10’dan %50’ye yükselmesi, tepe silindir basıncında %17,3, maksimum ısı salınım oranında ise %42,4’e varan radikal düşüşlere neden olmuştur. Hidrojen zenginleştirme stratejisinin bu performans kaybını önemli ölçüde kompanse ettiği gözlemlenmiştir; nitekim %50 tıkanıklık altındaki HEF60/360 K konfigürasyonu, ısı salınım performansı bakımından %10 tıkanıklıktaki HEF20/340 K baz değerini geride bırakmıştır. Ancak bu iyileşme, düşük HEF koşullarına kıyasla NOX emisyonlarında %35’lik bir artışı beraberinde getirmiştir. Çalışmada, ısı salınımı ve OH radikal konsantrasyonlarının non-lineer bir bozulma sergilediği %30 ile %40 tıkanıklık aralığı, kritik bir 'kirlenme eşiği' olarak tanımlanmıştır. Tanısal açıdan, artan tıkanıklıkla birlikte CH2O pik değerinin Üst Ölü Nokta (ÜÖN) civarından yaklaşık 20° Krank Mili Açısı (KMA) sonrasına sarkması, karakteristik bir 'soğuk alev zamanlama göstergesi' olarak literatüre sunulmuştur. Şiddetli tıkanıklık koşullarında OH radikalinin %70’e varan oranlarda baskılanması, bu türü yanma kalitesinin en hassas indikatörü haline getirmektedir. Elde edilen veriler, IMO Tier III emisyon standartlarına tabi deniz sevk sistemlerinde durum tabanlı bakım planlaması ve optimize edilmiş hidrojen karışım stratejileri için teknik bir kılavuz niteliğindedir.

Keywords

• Hidrojen/Dizel Çift Yakıtlı Gemi Makinesi
• Enjektör tıkanıklığı
• Hidrojen enerji fraksiyonu
• Emme havası sıcaklığı
• Yanma ve emisyon karakteristikleri

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