An experimental investigation on performance and emissions of a single cylinder dual fuel Diesel-CNG engine combined with EGR

Abstract

Natural gas plays an important role as an alternative fuel for gasoline and diesel engines. It has a promising future especially with the world crisis in fuel and the lower prices of natural gas compared to the prices of gasoline and diesel fuels. It can be used as a sole fuel in spark ignition engines because it has nearly similar properties as gasoline, but in diesel engines it is used as a main fuel while the diesel fuel is injected to the combustion chamber as a pilot fuel to be an ignition source. This paper investigates the performance of a small dual fuel engine where a single cylinder, four stroke water cooled diesel engine is converted to run on a dual fuel of diesel and compressed natural gas (CNG). An exhaust gas recycling system is used to introduce two ratios of EGR (Exhaust gas recirculation) to the engine. Effects of percentage of natural gas content and EGR ratio on engine performance and emissions are investigated for different engine loads. Based on the obtained experimental results, it can be concluded that the total reduction in engine thermal efficiency increases as the ratio of the used natural gas increases. A maximum reduction of about 5 % in engine efficiency is recorded when 80% of diesel fuel is replaced by natural gas to deliver the same engine power. Also, NOx emissions are decreased while CO is increased with utilization of EGR.

Analysis of the CNG impact оn some of the combustion parameters of dual-fuel compression ignition engines

“…According to various studies the usage of CNG as a gas fuel at dual-fuel diesel engines leads to decrees of the maximum cylinder pressure (P Zmax ) (Fig. 1 -based on the information in [3]) [3,4,5,6,7,8]. One of the reasons for this behavior is the increased ignition delay period at dual-fuel mode as a result of which a greater part of the combustion process is transferred to the expansion curve [4,5].…”

“…1 -based on the information in [3]) [3,4,5,6,7,8]. One of the reasons for this behavior is the increased ignition delay period at dual-fuel mode as a result of which a greater part of the combustion process is transferred to the expansion curve [4,5]. The lower flame propagation speed at gas-air mixture is also a contributor of the decreased cylinder pressure.…”

Experimental and numerical study of the pollution formation in a diesel/CNG dual fuel engine

“…However, in diesel engine, the trade-off relationship between NOx and particulate matter (PM) emissions makes it difficult to reduce these two emissions at the same time. In order to simultaneously reduce soot and NOx emissions while achieving high thermal efficiency, many strategies have been proposed in compression ignition (CI) engine, among which dual fuel combustion concept is the most promising method and has been aggressively investigated by engine researchers throughout the world [1][2][3][4][5][6].…”