Experimental Investigation of a Heavy-Duty Compression-Ignition Engine Retrofitted to Natural Gas Spark-Ignition Operation

Abstract

Heavy-duty compression-ignition (CI) engines converted to natural gas (NG) operation can reduce the dependence on petroleum-based fuels and curtail greenhouse gas emissions. Such an engine was converted to premixed NG spark-ignition (SI) operation through the addition of a gas injector in the intake manifold and of a spark plug in place of the diesel injector. Engine performance and combustion characteristics were investigated at several lean-burn operating conditions that changed fuel composition, spark timing, equivalence ratio, and engine speed. While the engine operation was stable, the reentrant bowl-in-piston (a characteristic of a CI engine) influenced the combustion event such as producing a significant late combustion, particularly for advanced spark timing. This was due to an important fraction of the fuel burning late in the squish region, which affected the end of combustion, the combustion duration, and the cycle-to-cycle variation. However, the lower cycle-to-cycle variation, stable combustion event, and the lack of knocking suggest a successful conversion of conventional diesel engines to NG SI operation using the approach described here.

RETRACTED: Numerical investigation of the effect of swirl number on performance, combustion, and emissions characteristics in a converted heavy-duty natural gas engine

“…All of these issues can be resolved by replacing a diesel injector with a spark plug and mounting a gas injector on the intake manifold, allowing the gas fuel to work in the Otto cycle rather than the diesel cycle (Aktas and Karyeyen 2022; Aktas 2022a, b, c). The main reasons why natural gas is preferred as a fuel are that it has less environmental damage, it is abundant due to the development of extraction technologies, and it is accessible and cheap, especially in the USA (Liu et al 2019). In addition, it is predicted that there will be a 20% conversion of heavy-duty diesel vehicles to natural gas-powered vehicles by 2025 in the USA (U.S EIA 2016).…”

A 0/1-Dimensional Numerical Analysis of Performance and Emission Characteristics of the Conversion of Heavy-Duty Diesel Engine to Spark-Ignition Natural Gas Engine

“…in both road and offroad vehicles can reduce the dependence on petroleum-based fuels by reducing engine emissions [5]. Among these alternative fuels, NG is one of the most remarkable fuels due to its high availability, cheaper price than diesel or gasoline, and less environmental damage [6]. It is predicted that the proportion of NG-powered vehicles in the United States may be approximately 20% of the total heavyduty vehicles by 2025 [7].…”

“…When the literature is examined, it is possible to come across a limited number of studies in which diesel engines are converted to work with NG only with the help of injector and spark plug replacement [6,12,[14][15][16]. These studies were mostly carried out experimentally, and the combustion characteristics of the cylinder that occurred in the use of NG in the diesel engine converted without any changes in the combustion chamber were investigated.…”

Numerical Investigation of the Effects of Engine Speed on Performance and Combustion Characteristics on a Converted Spark-Ignition Natural Gas Engine

“…Tüm bu problemlerin üstesinden ise dizel motorlarda emme manifolduna düşük basınçlı doğalgaz enjektörü ve dizel enjektör yerine ise buji montajı ile doğalgazın dizel çevrim yerine otto çevrimde çalışması sağlanarak gelinmektedir. Yakıt olarak ise doğalgaz tercih edilmesinin başlıca sebepleri ise çevresel zararının daha az olması, çıkarma teknolojilerinin gelişmesine bağlı olarak bol bulunması, özellikle ABD'de ulaşılabilir ve ucuz olması gösterilebilirken Türkiye'de dağıtım hattının arttırılması ile ilgili çalışmalar bulunmaktadır [8]. Ayrıca ABD'de ağır hizmet dizel araçların doğalgaz ile çalışan araçlara 2025 yılına kadar %20 oranında bir dönüşüm olacağı öngörülmektedir [9].…”